Wikipedia:Reference desk/Archives/Science/2009 September 29

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September 29

carbon monoxide as a nucleophile

Can I use carbon monoxide as a nucleophile for carbon-carbon conjugate addition or a direct attack on carbonyls? What happens to the triple bond? If some water is around, could I make a carboxylic acid with it? John Riemann Soong (talk) 00:01, 29 September 2009 (UTC)

Half the answers can be found at Carbon_monoxide#Organic_and_main_group_chemistry. CO is a nucleophile (lewis base), but:

I've never heard of CO reacting with carbonyl - it's isoelectronic with CN- and N2 . CN- does react with carbonyls [1] , but CO is much more like N2 in it's reactions (mostly due to its neutral charge) - it's unlikely to react. If it did you'd get: (with an acyl chloride)

        O-
        |
      R-C-C+=O
        |
        Cl

This could do many things - form an alpha lactone, and then eliminate CO2 giving a carbene, OR dimerise to give a 'di-lactone'..

Compare with a diazomethan compund - and how unstable they are - it's unlikely to form at all.

The Koch-Haaf reaction for formation of a carboxylic acid is pretty straightforward [2] [3] but requires strong mineral acid, and CO pressure around 100atm. The very reactive electrophile carbocation is made in situ to react with the CO.83.100.251.196 (talk) 02:23, 29 September 2009 (UTC)

tertiary amines and acyl chlorides

Tertiary amines actually react with acyl chlorides, right, just that the K isn't very favourable? (The amine is a better leaving group than Cl-?) If I found a way to remove the product, could I drive the reaction to completion and get a quaternary amine salt? John Riemann Soong (talk) 04:06, 29 September 2009 (UTC)

I do see literature examples of this reaction. Distilling the product from the reaction probably isn't useful: RCOX with X=Cl is more volatile than than with X=NR'₃, so you'd wind up distilling out the starting material and shifting the equilibrium away from RCON⁺R'₃. You need to remove the Cl...think about adding something MX' that replaces Cl with a non-nucleophilic anion X' so that MCl precipitates? On the other hand, if you pick a solvent in which RCOX and NR'₃ are soluble but the RCON⁺R'₃Cl^– salt is not, it precipitates out as it forms. DMacks (talk) 04:46, 29 September 2009 (UTC)

With cloride silver is always a joker! Silver halides are insoluable and precipitate and shift the equilibrium. If yo use a silver salt with a non-nucleophilic anion like nitrate than it should work.--Stone (talk) 21:36, 29 September 2009 (UTC)

Silver tetrafluoroborate (or Silver hexafluorophosphate) is a better choice - when working with organic compounds nitrate is one to avoid.83.100.251.196 (talk) 23:05, 29 September 2009 (UTC)

Male body area name?

What is the name of the area immediately above the penis, but far below the belly button? About the area a speedo swim suit covers up? --68.103.141.28 (talk) 04:14, 29 September 2009 (UTC)

It looks to me as though it's the lower part of the hypogastrium, or hypogastric region, or pubic region. (However, note that the diagram on the Wikipedia page seems to show that region extending farther down than the diagram on the University of Michigan page linked to from it. Maybe there is some disagreement.) --Anonymous, 04:50 UTC, September 29, 2009.

I'd say more like the pelvic/pubic region. bibliomaniac15 04:55, 29 September 2009 (UTC)

Pubis as noun, pubic as adjective, is a good approximation though common usage often includes the entire region including the inner thigh, as in pubic hair. However, the medical term is fairly specific, with the mons pubis (in men and women) overlying the symphysis pubis. -- Scray (talk) 09:37, 29 September 2009 (UTC)

It's worth pointing out that the above is the straight answer to the question, and everything after that has gone south. →Baseball Bugs ^{What's up, Doc?} carrots 05:04, 30 September 2009 (UTC)

Here is an image I found. The area in question is cropped and highlighted. Does this fatty patch in obese males have a name? It's well defined under the abdomen. I hear the word "pannus" referring to the belly overhang. But this area does not seem to have a name. How does it form? Why does an obese belly stop at the natural "seam" above this area and not grow into that area? --68.103.141.28 (talk) 03:52, 30 September 2009 (UTC)

This section is getting more educational by the minute. I'm fairly certain that rectangular area could safely be called the flabbis dunlappis. →Baseball Bugs ^{What's up, Doc?} carrots 04:38, 30 September 2009 (UTC)

Caused by Dunlaps Disease (aka The Spare Tire. Aka "His stomach done laps over his belt"). --Jayron32 04:48, 30 September 2009 (UTC)

Yes, I was presenting the formal Faux Latin name. The disease has obviously reached a point of severity, i.e. you can't tell if it's male or female. →Baseball Bugs ^{What's up, Doc?} carrots 04:50, 30 September 2009 (UTC)

According to this source it's a "flap." Bus stop (talk) 05:00, 30 September 2009 (UTC)

There's a video of this? TMI. →Baseball Bugs ^{What's up, Doc?} carrots 05:03, 30 September 2009 (UTC)

See Muffin top. Cuddlyable3 (talk) 23:39, 30 September 2009 (UTC)

Aboriginal North americans as stewards of nature

Growing up in north central Ontario, I was always told that Native Peoples were good stewards of nature and that as a culture they lived "in harmony" with nature. From an historical/archeological/anthropological perspective, how accurate is this? Wer Native peoples just as eco-unfriendly as we "white" folk are? —Preceding unsigned comment added by 209.161.230.65 (talk) 05:00, 29 September 2009 (UTC)

Native people were largely "eco-unfriendly". They did whatever best suited their interested with little regard for the long-term health of the environment. But then, after a few thousand years and a relatively small population an equilibrium can be reached. In much of North American native peoples used wildfire to thin forests and promote a "park land" type landscape that provided many benefits--such as drawing wildlife like deer, growth of berries, and the ability to see longer distances for defensive purposes. After European colonization took hold and native populations crashed the "open landscapes" rapidly became dense and dark. The "wilderness" that people like Thoreau wrote about where not ancient but the result of the extirpation of natives. There are numerous examples of native peoples overtaxing the environment to the point of ecological collapse. Finally, in the case of Plains Indians, once firearms and horses were acquired in significant numbers the toll on bison herds was severe. While the ultimate collapse of the bison must be blamed mostly on non-natives, there was a significant native contribution to the process (this is explored in some detail in the book The Comanche Empire). The case today may be different, as many native communities work hard to preserve the environment of their reservations (though to varying degrees). In some cases this contributes to the continued poverty in native reservations because the environmental regulations make it less attractive for natural resource extraction companies to do business there. I'm coming at this from the perspective of the Pacific Northwest--it may be different elsewhere. In Ontario, once Europeans came and began offering valuable trade goods in exchange for beaver pelts the natives very rapidly depleted beaver stocks over an extremely wide region. This would be one example of not living "in harmony with nature". Pfly (talk) 06:01, 29 September 2009 (UTC)

I think the idea that native peoples were careful stewards of nature until corrupted by colonial invaders is now recognised as a romantic over-simplification. The deforestation of Easter Island is thought to be largely due to overpopulation by native islanders, and the extinction of Australian megafauna such as Genyornis is thought to be due to hunting by early human settlers during the Late Pleistocene. Gandalf61 (talk) 11:04, 29 September 2009 (UTC)

There are also some good books, though I can't recall their titles offhand, about the massive agricultural projects of the natives of South America as well, which were fairly eco-unfriendly by modern standards. In all cases, though, compared to Europeans, the natives do pretty well, mostly they didn't have the technical ability to ratchet up their environmental exploitation exponentially. --Mr.98 (talk) 16:31, 29 September 2009 (UTC)

In that vein, I would recommend Jared Diamond's Collapse: How Societies Choose to Fail or Succeed as an excellent and accessible book on how environmental factors – and our responses to them – shape the success or failure of human societies. Wikipedia's summary of the book gives a taste of the contents. TenOfAllTrades(talk) 20:17, 29 September 2009 (UTC)

The introduction to that book in particular addresses this specific question. Diamond concludes that both the image of native peoples as "ecological stewards" and, on the other hand, the less-common idea that they were callous and wasteful of natural resources are both based on the false premise that they're fundamentally different from modern "civilized" people. He recommends considering them in the same terms one would consider any modern society - as a people faced with certain challenges, trying to overcome them as best they can (sometimes this would mean taking steps to protect the environment, other times it would mean doing thing we would consider environmentally harmful). Even if you're not up for taking on the entire book, checking out the few pages of the introduction that address this at a library or something might be worthwhile. -Elmer Clark (talk) 04:26, 2 October 2009 (UTC)

In some sense, they were "in harmony with nature": they'd been around long enough, doing the same things long enough, for nature to evolve and incorporate them into the ecosystem. --Carnildo (talk) 01:13, 30 September 2009 (UTC)

I thought that the Natives only came to North America in the last 10-15,000 years. That does not seem like sufficient time for anything to evolve. Googlemeister (talk) 13:17, 1 October 2009 (UTC)

That number is very much in flux at the moment. It's hard to gauge, but I think most archaeologists are coming around to accepting substantially older dates. However, we're still talking about a few tens of thousands of years, not millions or anything. "Evolution" in that context might not be the correct term, perhaps "adaptation" would be more correct. Matt Deres (talk) 03:49, 2 October 2009 (UTC)

i have a pancreas working with a capacity of 80%!!!

I am a diabetic since April, 1986. Test Result for H.Pylori IgG was 25 positive then after treatment became 6 Negative. Test Result for C-Peptide was 2.8 (80%)which means that my pancreas is functioning all the time. I want just an explanation as I still take insulin injection 50 American Units. My Doctor is giving me Galvus Tablets. thanks —Preceding unsigned comment added by Luckystar100 (talk • contribs) 09:32, 29 September 2009 (UTC)

This is not a place to give medical advise, as given in the guidelines at the top of this page. Please consult your doctor. Rkr1991 ^{(Wanna chat?)} 10:05, 29 September 2009 (UTC)

To start with, you can read the diabetes mellitus article, which may help you understand diabetes. However, for anyone to be able to give you a complete explanation would require them to have intimate knowledge of your medical history, such as your doctor. If you don't understand your medical condition, be persistent about asking questions at your next visit. Write them down ahead of time. Don't leave until you understand. If the doctor can't or won't take the time to explain it, ask the nurse. If nobody at the office is willing to educate you about your condition, then switch doctors. Your health is too important to accept mediocrity. There are plenty of bad doctors out there, but there are also plenty of good ones who will MAKE SURE that you understand what is going on in your body, so that you are fully invested in the treatment they offer you. --- Medical geneticist (talk) 13:48, 29 September 2009 (UTC)

0mph - Warp Drive in (?) seconds

Without in inertial dampener how many Gs would an astronaut feel when travelling at warp speed (or the speed of light, even), and wouldn't the rapid (instantaneous) acceleration kill said astronaut immediately? Getting into science fact and rather than science fiction, what is the top speed that a human could safely travel in space without experiencing the effects of high speed usually felt here on earth? --KageTora - SPQW - (影虎) (talk) 10:00, 29 September 2009 (UTC)

As far as we know, nothing material can travel at "Warp speed" or even the speed of light. Abstracting from indirect effects, astronauts can travel safely at any speed less than the speed of light, though. Speed is not acceleration. To reach a given speed, an astronaut has to accelerate, but he can accelerate as slowly as desired - at the cost of reaching his or her target speed later. You don't usually feel any effect of high speed on Earth either, but high speed often goes hand in hand with significant acceleration (e.g. when turning). --Stephan Schulz (talk) 10:07, 29 September 2009 (UTC)

Speed does not kill you, ever. Not even here on earth. It is acceleration that kills you, if it is sufficiently large. So no, an astronaut travelling arbitrarily close to c would not feel any acceleration (Gs). And, if concepts such as the Alcubierre drive ( http://en.wikipedia.org/wiki/Alcubierre_drive ) turn out to be possible, even people traveling at "warp speed" would not feel acceleration. —Preceding unsigned comment added by 157.193.173.101 (talk) 10:10, 29 September 2009 (UTC)

:That reminds me of what my father in law used to say, who had once been in the RAF: "It's not the speed that kills - it's the sudden stop!" --TammyMoet (talk) 10:24, 29 September 2009 (UTC)

Similarly, falling off a tall building doesn't kill you. Cuddlyable3 (talk) 13:56, 29 September 2009 (UTC)

(EC)Thanks, so this is getting close to what is confusing me. What is it that makes a person in a centrifuge black out (and eventually die)? They are travelling at extremely high speed (of course, they have accelerated to that speed in order to get there, but after a while the speed is (or can be) kept constant). Is it because they are continually 'turning', so to speak? I can't understand that, because if the turning itself is constant, would it not be the same as going in a straight line? --KageTora - SPQW - (影虎) (talk) 10:25, 29 September 2009 (UTC)

No. A body left undisturbed will travel a straight line. In a centrifuge, bodies travel in a circle. They are constantly accelerated towards the center of that circle by a centripetal force. This is perceived by people in a centrifuge as a centrifugal force. When the centrifuge starts, there is an additional force that accelerates it sideways (and that can be felt or measured by the passengers), but that is not the major force that centrifuges are built for. --Stephan Schulz (talk) 10:46, 29 September 2009 (UTC)

We have an article, circular motion, that explains this important fact - motion in a circle is constantly accelerating - and in a different instantaneous direction, always tangential to the velocity. Nimur (talk) 11:59, 29 September 2009 (UTC)

If someone had a spaceship capable (don't ask me how) of sustained 1 G acceleration (like normal Earth gravity), starting in orbit, then the speed (neglecting relativistic effects) would be the acceleration times time. How fast would he be going in one month (neglecting relativity)? (9.8 meters/sec²)*(1kilometer/1000 meters)*(3600 seconds/hour)*(24 hours/day)*(30days/month)=25401 kilometers/second after one month, or about 1/12 the speed of light. (Fitzgerald contraction should be less than a 1% effect so far). Keep up 1 G of acceleration for a year and amazing relativistic effects would kick in. Thus neither high accelerations nor "inertia dampers" would not be needed to gain high speeds. (feel free to throw in relativistic refinements which keep our travellor from reaching c after a year.) Edison (talk) 13:38, 29 September 2009 (UTC)

I won't ask how someone's spaceship works but all of its 1G thrust capability would first be directed to escape from orbit, so the speed after a month would be less than you calculate. Cuddlyable3 (talk) 13:56, 29 September 2009 (UTC)

For this sort of back-of-the-envelope exercise, the rounding errors are going to be larger than the effect of Earth's gravity. The escape velocity from the surface of the earth is only about 11 km/s; one hits that after less than 20 minutes of straight-line one-gee acceleration. (And yes, I do realize that that number contains some slightly inaccurate approximations as well.) After a month, the contribution of relativistic effects will be a bigger concern than Earth's gravity well. TenOfAllTrades(talk) 14:11, 29 September 2009 (UTC)

With relativistic corrections, how far could the 1G spacetraveller go in 1 year and in 10 years (ship time) (allowing 1/2 the time to accelerate and 1/2 the time to decelerate, all the while experiencing effectively Earth gravity (except for "turnaround" at the halfway point). Nonrelativistically, it seems he would go about .26 light year in a year, reaching a maximum speed of about .5 c. But in the 10 year case relativity would have a strong effect, since otherwise he would have reached a speed of about 5c after 5 years, if he could have kept adding 1/12 c per month to the speed as he did initially.(This is emphatically not a homework question, but my calculus is rusty). Bonus: In one year or ten years as experienced by the Girl He Left Behind on Earth, how much time would have passed for the spaceman? Edison (talk) 15:53, 29 September 2009 (UTC)

A website with a relativistic calculator says that at 1 G constant acceleration, and turnaround and deceleration from the midpoint, the spaceman would in 10 years ship time, travel 167 lightyears, reaching a maximum velocity halfway of .0.99993 c, while the person left back on Earth would have experienced 169 years. The calculator says that for 1 year (ship time) at 1G, the distance would be .264 lightyear, at a max speed halfway of .475 c and that the Earth observer would have experienced only 1.045 years. A 20 year trip (shiptime) at 1G would take him 30000 lightyears, while 30001 years passed on Earth. Impressive, but boring compared with "Engage warp drive!" and being lightyears away in a few hours. Long-sustained (over months or years) 1G acceleration seems impossible with onboard energy driving it. Edison (talk) 16:37, 29 September 2009 (UTC)

What is impressive is that at 1G you could reach the each of the observable universe (at least, where it now) in less than 50 years (if you didn't want to stop - a little under 100 years if you want to stop at the end). That is basically the largest distance that has any significant meaning and you can get there in a human lifetime at the acceleration that humans have evolved under. I think that is really impressive. --Tango (talk) 17:01, 29 September 2009 (UTC)

The interesting consequences of that sort of travel are explored in Poul Anderson's science fiction novel Tau Zero. I recommend it for fans of hard science fiction. TenOfAllTrades(talk) 20:07, 29 September 2009 (UTC)

Tau Zero had a fascinating concept, but the author neglected general relativistic calculations; as the ship continued to travel, it would inevitably enter a region of space in which the velocities of nearby particles were less than rediculous (the same reason the oldest neutrinos in the universe, produced shortly after the big bang, are predicted to be moving somewhat slowly). And since the ship isn't going fast enough through the entire crunch/bang cycle, the process happens fast enough that quantum effects won't save it (or at least that's what I surmised/recalled as saving the ship, please correct me if I'm wrong). Someguy1221 (talk) 05:09, 30 September 2009 (UTC)

Are you saying the ship will be (kind of) redshifted by the universe expanding, meaning it will be moving slower relative to the objects it is passing than it is going relative to Earth? What kind of redshift do you get over those distances? Would it make much difference? --Tango (talk) 21:44, 30 September 2009 (UTC)

Something like that. You may know that in Special Relativity the Velocity-addition formula is a bit more complicated than it is in classical mechanics. In general relativity, the equations get insanely beyond my understanding [4]. The best I can give you is that it was once explained to me, in the discussion of that very book, how the formula works out for a near light-speed ship going far enough. Someguy1221 (talk) 06:23, 1 October 2009 (UTC)

moment of inertia

why second moment of inertia is needed —Preceding unsigned comment added by Blossomragav (talk • contribs) 12:14, 29 September 2009 (UTC)

The second moment of inertia is, apparently, the same thing as the second moment of area: a measure of the resistance of a shape to bending and deflection. Our article goes into a great deal of mathematical detail. TenOfAllTrades(talk) 12:22, 29 September 2009 (UTC)

...and it is needed in the Euler–Bernoulli beam equation. Gandalf61 (talk) 12:32, 29 September 2009 (UTC)

Abdominal pain

I think it's safe to say that most people, if not all, have on occasion experienced mild to moderate abdominal pain. If the pain is severe, people would see the doctor, but often the pain is not severe enough and the symptom disappears fast enough that the cause is not investigated. Are there good statistics on the leading causes of non-recurring mild to moderate abdominal pain? (I.e. data on what % of undiagnosed cases are actually caused by some condition X. Some candidates for X that come to mind are food poisoning, constipation, and menstrual cramp.) Physiologically what are the mechanisms for the underlying conditions to manifest as abdominal pain? —Preceding unsigned comment added by 173.49.10.73 (talk) 12:27, 29 September 2009 (UTC)

Appendicitis is another cause of intermittent abdominal pain. Edison (talk) 13:22, 29 September 2009 (UTC)

Rather than a trying to list causes here, I'd recommend looking at abdominal pain. Those are mostly disorders that will probably end up getting diagnosed at some point because the symptoms will get severe enough to come to medical attention. I doubt there are any good data on "what % of undiagnosed cases are actually caused by some condition X." If we knew the cause, they wouldn't be undiagnosed, and if the cause of abdominal pain is never investigated, there's no way to know. You might as well just pick numbers out of thin air. --- Medical geneticist (talk) 13:41, 29 September 2009 (UTC)

(ec)So is pregnancy. But it's safe to say that there are no good statistics about causes of pains that are often not reported or investigated. Cuddlyable3 (talk) 13:43, 29 September 2009 (UTC)

Is that safe to say, though? I would actually be quite surprised if there hadn't been at least some study of 'everyday aches and pains', including studies targeting mild or idiopathic abdominal pains. It's the sort of thing that manufacturers of over-the-counter analgesics, anti-inflammatories, constipation, and indigestion remedies are apt to look at quite closely. Those manufacturers would want to know about

• the incidence of such aches and pains;
• the frequency and duration of pains that would prompt a person to self-medicate (pains severe enough to attract attention, but not severe enough to lead to a doctor's visit and prescription);
• the types of pains, by body part, demographic group, underlying medical condition, etc. (to target the advertising campaigns); and
• the root cause (if any) of the symptom (to know what warnings need to go on the package insert, and to scare away lawsuits).

While it's out of my area of expertise (and I don't have time to do extensive digging at the moment), I would be shocked if there weren't studies where, for example, participants were required to keep a log of all their aches and pains for a period of time, and where clinicians made efforts to fully diagnose every little twinge. If the sample group were properly selected, there's no reason not to generalize the results out to the general population. TenOfAllTrades(talk) 14:28, 29 September 2009 (UTC)

Those would be pains that are investigated. Cuddlyable3 (talk) 18:43, 29 September 2009 (UTC)

But they are pains that are "often not reported or investigated" — and I've offered at least a partial response to the original poster's question. TenOfAllTrades(talk) 19:58, 29 September 2009 (UTC)

Well, by far the most common cause of abdominal pain is indigestion. That's why Rolaids and Tums are such big products. Looie496 (talk) 23:51, 1 October 2009 (UTC)

Force Practice

I have no clue where to begin! "Two horizontal forces, 225 N and 165 N, are exerted on a canoe. If these forces are applied in the same direction, find the net horizontal force on the canoe." Accdude92 (talk) (sign) 13:19, 29 September 2009 (UTC)

Addition. Cuddlyable3 (talk) 13:36, 29 September 2009 (UTC)

What you want to do here is add the force vectors. Since we're only concerned with horizontal forces there's only one axis to be concerned with. If they're both in the same direction, for simplicity you can call that direction the "positive" direction. So you just need to add +225N and +165N. 13:40, 29 September 2009 (UTC)

Ok what about "If the same two forces as in the previous problem are exerted on the canoe in opposite directions, what is the net horizontal force on the canore? Be sure to indicate the direction of the net force."

Also, i am not asking for the answer, I just really dont understand this.Accdude92 (talk) (sign) 14:03, 29 September 2009 (UTC)

You should ask your teacher if you're incapable of doing your own homework. Not trying to be unhelpful - they're there to help you! They also have access to diagrams, which I don't. Vimescarrot (talk) 14:17, 29 September 2009 (UTC)

Try thinking of it less abstractly. Let's say Person A and person B push things. If they both push the same direction, what happens? If they push in opposite directions, what happens? ~ Amory (user • talk • contribs) 14:33, 29 September 2009 (UTC)

It might be unintuitive, even to somebody who is thoroughly trained in physics - but forces add linearly. For lack of a better reason, we define forces to be "that conceptual thing which adds linearly to equal the acceleration, scaled by the inertial mass." So, if two workers were pulling at 225 and 165 newtons, the net force would be the sum. Maintaining a constant force, while another worker pulls with a separate force, is a technical or engineering challenge; but for simple physics problems, just assume that everything is attached by non-elastic ropes that are tensioned by perfect 165.000 newtons of force. Nimur (talk) 14:59, 29 September 2009 (UTC)

Except one of the ropes has 225 N tension.

Forget the canoe. Forget the horizontal. The heart of the question says: If two forces of strengths A and B are applied in the same direction, what is the net force?" The answer to that is "Force A+B in the aforementioned direction." The solution to your problem is to begin by reintroducing what I asked you to forget, and to include the units of force N = Newton after the values of A and B. Cuddlyable3 (talk) 18:38, 29 September 2009 (UTC)

Oral collagen

Why is collagen not hydrolysed when taken orally? I assumed all proteins had an oral bioavailability of 0. --Mark PEA (talk) 15:49, 29 September 2009 (UTC)

As per the collagen article: "Collagen is also sold commercially as a joint mobility supplement. Because proteins are broken down into amino acids before absorption, there is no reason for orally ingested collagen to affect connective tissue in the body, except through the effect of individual amino acid supplementation.". In other words, it doesn't really do what it's being sold to do. The fraud is kept within legal bounds by careful wording on the package. Red Act (talk) 17:00, 29 September 2009 (UTC)

Collagen is indeed hydrolyzed and digested (albeit this study was in rats and snakes). This study: AKG Jones, 1986. Fish bone survival in the digestive systems of pig, dog and man in D. Brinkhuizen & A Clason (eds.) Fish and Archaeology. Oxford, British Archaeological Reports International Series 294: 53–61, unfortunately not available online demonstrates this in humans. By the way, colostrum contains immunoglobulins that are able to cross the gut barrier in infants (mammals). Axl ¤ [Talk] 18:25, 29 September 2009 (UTC)

Electricity in a house

Why are there two wires for supply of household electricity?Since only one of them is required the other being the earth itself? —Preceding unsigned comment added by 113.199.176.92 (talk) 16:41, 29 September 2009 (UTC)

There are live, neutral and earth. Live and neutral are the ones that enter the house from outside - you need two wires in order to have a complete circuit. Earth is only there for emergencies and is usually earthed at the house itself, so there won't be a wire entering the house for it. --Tango (talk) 16:44, 29 September 2009 (UTC)

Our article on mains electricity explains this quite well.--Shantavira|^{feed me} 17:11, 29 September 2009 (UTC)

Earth has some resistance as a conductor and if it were used as a return path for household electricity there would be problems with voltage loss at any distance from the generator, ground heating by high current close to the generator and disturbance to equipment that relies on a signal ground. Cuddlyable3 (talk) 18:16, 29 September 2009 (UTC)

If earth were used as a return path for household electricity, equipment that uses half-wave rectification of the supply would pass a DC into an earthing rod which would corrode it. Cuddlyable3 (talk) 18:22, 29 September 2009 (UTC)

Interesting point about half wave rectification. I wondoer how many equipments now still use it?--Tappet (talk) 21:22, 29 September 2009 (UTC)

See Earthing systems for the ground rules--Tappet (talk) 21:27, 29 September 2009 (UTC)

Single-wire earth return does exist - but although it cuts distribution wire construction costs, it brings significant extra costs in terms of efficiency loss, safety hazards (and costs to mitigate those hazards), and power quality (e.g. poor power factor correction capability). Nimur (talk) 21:01, 29 September 2009 (UTC)

Single-wire earth return is possible for high voltage (= low current) distribution using isolating transformers but the OP asks about household electricity which I take to be 240 or 120 VAC. Many houses on Earth are not on earth, meaning that a house built on a rock outcrop has no earth return. Cuddlyable3 (talk) 23:35, 30 September 2009 (UTC)

Detox, heavy metals in food

Although I despise the whole New Age nonsense of detox, I do believe that certain foods - like fish - could be contaminated with heavy metals, like mercury; and if a person eats fish regularly, these heavy metals will accumulate in his body. Is this true? If yes, is there a way of detoxing our body? --Quest09 (talk) 17:15, 29 September 2009 (UTC)

Yes, eating too much fish is the most common way to wind up with mercury poisoning. My niece got murcury poisoning after eating large amounts of tuna fish over a half-year period. See the mercury poisoning article for how mercury poisoning is treated. Also see mercury in fish. Red Act (talk) 17:24, 29 September 2009 (UTC)

The process is called bioaccumulation. That said, there's no real way to detox yourself. You can treat acute poisonings with chelating agents and similar, but these new-agey things are all bogus. Actually 'new age' is perhaps anachronistic, since I think most of those ideas go back to the late 19th century (but even before that you had 'purging' of various sorts, leeches, etc.) Way back before bioaccumulation was known as scientific fact. --Pykk (talk) 18:24, 29 September 2009 (UTC)

According to bio accumulation, that works because the mercury is stored in fat, so are there any publications suggesting liposuction as a treatment? Googlemeister (talk) 19:57, 29 September 2009 (UTC)

Never heard of that, but the worst way to get rid of all the fat-loving toxines, like mercury, DDT and dioxines is breast feeding. Not very nice for the baby but, if you loose nearly all your bodyfat during the breast feeding time most of the toxines will end up with the baby. I read the warning that mothers were warned not to go onto a strict fat free diet during breast feeding. So --Stone (talk) 21:30, 29 September 2009 (UTC)

Well, how can I get rid of my toxines if I have no baby and I am not even female? I suppose that when I get fat and make a diet afterwards, I will be loosing mercury along the fat, wouldn't I? And which mercury is the real danger for us? The mercury stored in fat or the mercury that reaches other organs - like the brain? Or will the mercury stored in fat someday be released and reach other organ where it can cause real damage? Quest09 (talk) 15:30, 30 September 2009 (UTC)

The problem not being female is not solvable. If you go on a diet you do not loose the fat loving toxins, as there is no natural way that your body will give away the highly caloric fats. The evolution made it the way that you use them for long term storage. The diet will mobilize the toxines, and they will go wandering around in your body, and it is possible too get really ill by the toxines, especially if they are reach other organs like the brain or the liver. The water soluable toxines are easier to deal with they normaly go with the urin.--Stone (talk) 18:16, 30 September 2009 (UTC)

The best way to get rid of the toxines is not to eat them.--Stone (talk) 18:17, 30 September 2009 (UTC)

Just FYI, the usual spelling in English (whether American or British) is toxin, with no e. Wiktionary lists toxine in Dutch and French. --Trovatore (talk) 19:15, 30 September 2009 (UTC)

Is it just me or did someone else expect Stone to mention male lactation? --antilived^{T | C | G} 07:24, 1 October 2009 (UTC)

When Viktor Yushchenko was poisioned with dioxins he supposedly ate lots of Olestra (a fat substitute which has the unfortuate side effect of being a laxative). As it travelled through his gut the fat solube dioxins moved into the olestra and after many repeated treatments the toxins were eventually removed. If you were heavily poisoned as he was you'd lose some of the toxins eating normal food but this sped things up as he could eat loads of it without getting fatter! Here is a link, there isn't anything in any of the articles yet about it. Smartse (talk) 14:24, 4 October 2009 (UTC)

The mercury content of fish varies considerably with the species. Sardines/pilchards have the lowest amount as they are young fish and do not have time to accumulate so much mercury in themselves. As far as I recall Shark has the highest - a websearch will find a table of mercury in various species. Eating fish has many health benefits, so it would be a mistake to avoid them. I once constructed a table of the ratios of Omega3 to mercury for various species - if I can find it I will post it here. 78.149.224.55 (talk) 10:14, 5 October 2009 (UTC)

Cast Iron History

The unseasonable drought has revealed some cast iron structures in some of what is normally moat in my garden. I am not sure if they are certainly modern or possibly historic (in the context of my garden by historic I mean pre Black Death). I obviously know that Iron dates to the Iron age but can anyone give a guide to e.g. when they might have had blacksmiths making squared iron rod, and how much was used in practice, and how much survives today? There is a lot of iron in old buildings but I am not sure if it is a later add on. The fact this has survived (ish) underwater may or may not say something about the quality but it looks like it might be a grid for separating part of the moat into a kitchen pond (for carp to be eaten soon) or similar. Does much medieval iron work still exist? --BozMo talk 20:53, 29 September 2009 (UTC)

Sure, for instance.. I'm not sure what the proper English architectural term is, but Germans call them (beam-)anchors. I'm talking about the iron brackets which anchored the wooden floor-beams to the load-bearing wall in medieval buildings. They're usually still in place, they're even used to date buildings sometimes. I don't think metal quality would affect how long it'd last underwater as much as the oxygen conditions. If there's little oxygen, it could probably last quite some time. (the iron bits of the Vasa were intact after over 400 years underwater). --Pykk (talk) 23:00, 29 September 2009 (UTC)

Anchor plate (and other names [5] ) common on medieval (and newer) buildings - not sure of medieval ones - but they must have existed.83.100.251.196 (talk) 00:15, 30 September 2009 (UTC)

Pattress plate is the UK term [6]

History_of_ferrous_metallurgy#Medieval_to_modern_Europe All the blacksmith needs to do is hammer it out. Consider medieval portcullises. Also consider medieval iron hinges [7] etc - well within the abilities from the 10th Century and beyond, and probably before.

There are examples of using iron bar in construction pre black death eg [8] p255 footnote 2.

Also consider the production of swords - which requires iron bars. There's still a lot of iron work from the medieval period surviving in churches (eg [9] 11th or 12th century ironwork for doors), as for more everyday stuff - I don't know.83.100.251.196 (talk) 23:44, 29 September 2009 (UTC)

What is the thing you found? Is it some sort of grill - letting little fish out?83.100.251.196 (talk) 23:45, 29 September 2009 (UTC)

Yes, some sort of grill I think but it is mainly buried in sludge now. that area has been abandoned for a very long time --BozMo talk 05:36, 30 September 2009 (UTC)

• It is probably NOT cast iron - which is brittle and cannot be formed by hammering or similar processes. Furthermore, cast iron wasn't made before the 15th century. You probably have some wrought iron there... --Janke | Talk 06:41, 30 September 2009 (UTC)

As an aside, I think it's probably not a medieval fish grill, simply because of the expense of iron in those times meant it was mostly used where other materials would not suffice - some sort of wicker (or water reed) woven fish trap would seem like a cheaper alternative.

Additionally your local (county) archaelogy department would be interested, and I think investigate these things if you tell them - they will almost certainly have a look for free, and should be able to tell of it's origins. Suggest your local county council website an look for archaelogy. 83.100.251.196 (talk) 23:29, 30 September 2009 (UTC)

It might be a wrought iron gridiron or grating and have been thrown in the ditch when it was no longer needed or useful. Edison (talk) 04:54, 2 October 2009 (UTC)

Sunburn

Can dark skinned people suffer from sunburn? How do they knew they have it. what effects does it have . Are they more susceptible to skin cancer/--Tappet (talk) 21:42, 29 September 2009 (UTC)

They definitely can, and it hurts just like for white folks. I can't tell you anything about their probability of getting skin cancer compared with whites. →Baseball Bugs ^{What's up, Doc?} carrots 21:45, 29 September 2009 (UTC)

YES, I'm amongst them!!!--Leon (talk) 17:04, 30 September 2009 (UTC)

How about an actual reference here. From our article melanin:

Dark-skinned people, who produce more skin-protecting eumelanin, have a greater protection against sunburn and the development of melanoma, a potentially deadly form of skin cancer, as well as other health problems related to exposure to strong solar radiation, including the photodegradation of certain vitamins such as riboflavins, carotenoids, tocopherol, and folate.

Comet Tuttle (talk) 22:37, 29 September 2009 (UTC)

Greater protection, yes, but not absolute protection. →Baseball Bugs ^{What's up, Doc?} carrots 23:18, 29 September 2009 (UTC)

You can tell the exact same way you would for a light-skinned person - their skin will be darker. It may be a less noticeable contrast, but the skin will most definitely be darker (tan) or redder (burned). If you have any friends or acquaintances you are close with, it should be obvious. ~ Amory (user • talk • contribs) 00:09, 30 September 2009 (UTC)

To be entirely accurate it must depend on exactly how dark skinned they are. Where I used to live in West Africa the range of skin tone went through deep browns to totally coal black. The only ones who got burned (pretty much on the equator) were Albinos or ones who were brown enough to mean they were teased for being "Metisse". --BozMo talk 08:32, 30 September 2009 (UTC)

who coined the term anti matter ?

lately , ive been arguing with a friend of mine who thinks anti matter is an esoteric concept and i was trying to find the name of the scientist who coined the term but im not sure wich of the scientist mentioned in the article on the subject actualy coined it

thanks for the help —Preceding unsigned comment added by 72.0.206.235 (talk) 23:39, 29 September 2009 (UTC)

I suspect it was Paul Dirac in 1928 because it was his discovery of the Dirac equation that predicted the positron - which is antimatter. However, he first called the positron a 'hole' - so it's not clear whether the term antimatter originates with him. SteveBaker (talk) 00:55, 30 September 2009 (UTC)

The word "positron" was coined by Carl D. Anderson, who was the person to experimentally discover the predicted positrons (the first known form of antimatter), in 1932. However, I don't know if Anderson used the term "antimatter", either. Red Act (talk) 01:14, 30 September 2009 (UTC)

According to the OED, Dirac was using the term "anti-electron" by 1931, before Anderson's discovery. The OED has no quotes for "anti-matter" before 1953. Algebraist 01:21, 30 September 2009 (UTC)

The OED Supplement has a combined entry for all uses of anti- in reference to antimatter. This item would have been compiled in the 1960s; the OED Online might have a newer version. In the Supplement, the earliest cited usage is indeed by Dirac, in a 1931 paper: "We may call such a particle an anti-electron". The first cite shown for "antiparticle" and "antineutrino" is from 1934, for "antiproton and "antineutron" from 1942, for "anti-nucleon" from 1946, and for "anti-matter" from 1953. The writers' names are not given for any of these cites except the 1931 one.

However, because it is a combined entry, all the cites are just illustrating various uses of "anti-"; they can't be assumed to be saying that "antimatter" was not used before 1953, only that it was not used (that they know about) before 1931.

--Anonymous, 01:25 UTC, September 30, 2009.

That's one of those tricky ones though - having coined the 'anti-' prefix for the electron - then Dirac had set the terminology for those who came later - nobody was going to call the anti-proton the "unproton" or the "opposite-proton" or (god forbid) the "notorp". So the words anti-proton and so forth were effectively decided by Dirac's choice of 'anti-' for the positron (although it's kinda ironic that few people talk about 'anti-electrons' anymore). So when you're talking about opposite matter in general, the term 'anti-matter' was a forgone conclusion. If Dirac himself didn't actually use the term - he did (in a sense) coin it by forcing the future choice of vocabulary. SteveBaker (talk) 02:03, 30 September 2009 (UTC)

Your IP address indicates you might be in Montreal. If your friend is there, too, why not invite him/her to go to the Ville Marie Nuclear Imaging and PET/CT Center, 2345 rue Guy downtown and take a look at their positron emission tomography scanner, which shoots antimatter into people's brains! It can't be too esoteric when most large metropolitan areas in the industrialized world have such facilities. --Sean 16:06, 30 September 2009 (UTC)

Actually, in PET, the antimatter comes out of people's brains. What goes in is a radioactive substance that emits positrons (hence positron emission tomography). --Trovatore (talk) 21:30, 30 September 2009 (UTC)

I looked in Google Book Search for the first usage, but they are useless, between incorrect dates on scanned works (they typically use the first year a journal was published as the year of publication for an article many decades later) and everything being "no preview." You have to check the actual copyright page. Google Scholar has a source stating that the term "antimatter" was coined by Sir Arthur Schuster in 1898, and as support offers a website [10] as support. This in turn cites "Quantum Generations: A History of Physics in the Twentieth Century" by Helge Kragh, Princeton University Press, 1999, and links to the publisher's website, which is the source for the Schuster 1898 credit. I could not find at Google Book search an 1898 publication by Schuster. Schuster was the predecessor of Rutherford as Langworthy Professor, supported Einstein's Special Relativity in lectures in 1908. He was vice president of the Royal Society 1919-1920). He lived until 1934 and published a fair amount, so his coining of the term, even in a period before Dirac's theories, might have been known to the next generation of physicists.Edison (talk) 17:39, 30 September 2009 (UTC)

Schuster is credited with publishing about negative matter in Nature in 1898 in Gordon Fraser's "Antimatter-the ultimate mirror (2000). Fraser says (p3)that "almost everyone had forgotten" Schuster's 1898 letter when Dirac predicted duality in 1927, but that the duality was what Schuster "had suggested." So perhaps someone could find the 1898 letter and cite it in the Schuster article, which does not credit him with anything related to antimatter. "Cosmology: the science of the universe" by Edward Robert Harrison says (p433) that the 1898 writing was the first speculation about antimatter. Schuster is quoted by Harrison as concluding his 1898 Nature letter: "Astronomy, the oldest and most juvenile of the sciences, may still have some surprises in store. May antimatter be commended to its care!" Another source says he published two letters on antimatter in Nature in 1898. There is no mention of Schuster in the Antimatter article, but various books and articles credit him with coining the term as well as the concept, although his hypothetical antimatter would have repelled normal matter. Edison (talk) 18:13, 30 September 2009 (UTC)

Interesting find. I fixed your Schuster link, btw. Sounds like it would be worthwhile adding something about this to his article. --Anon, 18:21 UTC, September 30, 2009.

I added Schuster's hypothesis to Antimatter and to Arthur Schuster. Those skilled in wordsmithing and/or theoretical physics might take a look and see if it needs any tweaking. We still need an exact citation for the Nature letters of 1898. Edison (talk) 18:36, 30 September 2009 (UTC)

Found one of his 1898 letters free at Google Books: [11] Schuster, Arthur, "Potential matter: a holiday dream." Nature, 58, 367 (18 August 1898) doi:10.1038/058367a0. Pretty different from 20th century predictions of the properties of antimatter. Here is the other letter, in which he credits Karl Pearson with prior work which implies "negative matter." Edison (talk) 18:53, 30 September 2009 (UTC)

The OED online has not picked up the Schuster usage. They still have Dirac's 1931 usage of anti-electron as first cite, with 1953 being their earliest usages of anti-matter (in the NY Times on October 23rd, and slightly earlier in "Sci. News Let." on March 14th". The OED last updated this section in 1989. Have they not heard of Schuster, or did he never use the term antimatter? Dbfirs 09:26, 1 October 2009 (UTC)

Click on the link I provided, and you will see that Schuster definitely used the term "antimatter" in the 1898 letter to Nature. OED should correct their error. Edison (talk) 04:52, 2 October 2009 (UTC)

I clicked on both your letter links but no preview was available. The search was for "potential matter", not "antimatter". The Google scholar link leads to a dead source link. Only the claim at antimatterenergy.com supports use of the word "antimatter" and I suspect that this is a later interpretation. Dbfirs 11:57, 2 October 2009 (UTC)

Schuster wasn't talking about the same thing, and neither his theory or terminology ever got any widespread support. So it's your error, not the OED's error. Isolated cases of usage of a word don't make it into dictionaries, which are supposed to reflect common usage. Unless there's some evidence that the later usage of 'anti-matter' borrowed the term from Schuster, then it's irrelevant trivia. --Pykk (talk) 06:04, 2 October 2009 (UTC)

thank you so much for all the effort , this is very helpfull —Preceding unsigned comment added by 72.0.206.235 (talk) 22:58, 2 October 2009 (UTC)

Hunger Mechanism

There was a question several days ago which mentioned being IV-Fed all the nutrients a human would need. I'm wondering, if someone was hooked up to this, would they still feel hunger?

That is, is hunger a sensation of needing nutrients or does the stomach need a physical digestive process to satiate the hunger feeling?216.15.125.41 (talk) 23:50, 29 September 2009 (UTC)

Hunger is a sensation due to a specific neurotransmitter that sends messages from the stomach - I'm assuming - to the brain that tells it "enough." I'm not exactly sure what the "hunger-stopping neurotransmitter" is, but I know for sure that hunger is caused and stopped by a transmitter. Some obese people, or people that cannot stop eating, lack this, which is the reason for their uncontrollable consumption of food. About the IV-Fed, theoretically, if this IV triggered a specific element to send these messages to the brain, then yes; likewise, much like endorphins and pain, it could be our own sensation, caused my the taste of a specific food that release these "hunger-stopping neurotransmitters" to the brain. Hope this somewhat helped. 74.184.100.154 (talk) 01:01, 30 September 2009 (UTC)

See Hunger#Biological_mechanisms, Ghrelin and Leptin. Fences&Windows 02:45, 30 September 2009 (UTC)

OR: I experienced a saline drip that made me feel "over watered" i.e. the opposite of thirsty. Cuddlyable3 (talk) 08:21, 30 September 2009 (UTC)

Tube feeding is more common that IV feeding. Experiments have been done with volunteers who swallowed a balloon attached to a feeding tube, so that the stomach could be filled to varying degrees with food which the body did not get to digest, to see if the subject felt less hungry with a full stomach. Satiety is a function of several factors, including the experience of seeing, smelling, chewing, tasting and swallowing the food. Unfortunately I can't find the book which summarized the results, but I recall that nondigestible stomach filling did not eliminate hunger. For some reason they do IV feeding for premature babies, but not for grownups who are dying and wasting away from something like COPD. They just give IV water and electrolytes, but not enough calories to maintain weight along with vitamins, protein and minerals like they do the premies. Edison (talk) 17:24, 30 September 2009 (UTC)