Science desk
< July 6	<< Jun \| July \| Aug >>	July 8 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

July 7

Black olives...

Why do black olives taste nice to me on a pizza when combined with other flavours (tonight's topping was cheese, tomato, doner meat and olives), yet taste absolutely foul when eaten by themselves? --Kurt Shaped Box 00:15, 7 July 2007 (UTC)[reply]

Maybe because it was masked by the other flavors? Black olives taste like vulcanized rubber to be, regardless of whether it's by itself, on pizza, or with other toppings. bibliomaniac 15 ^{BUY NOW!} 01:39, 7 July 2007 (UTC)[reply]

"Black" olive is a loose term for a huge number of styles, marinades, and flavors of olive. Some indeed taste like rubber. Quality black olives are a delicious treat by themselves or with other food. I recommend Kalamata olives, instead of the canned junk you probably tasted. You can get them at a Greek, Middle Eastern, or other grocery store. Nimur 05:27, 7 July 2007 (UTC)[reply]

Yeah, but the stuff you get on a pizza is almost always the California black olive, which is an unfermented Mission olive, with pretty much no character (and, I think, still some remnant flavor of the lye, but I may be imagining that.) --jpgordon^∇∆∇∆ 15:22, 7 July 2007 (UTC)[reply]

And thank you for the link to doner meat. I didn't think it had anything to do with the Donner Party but I liked having the link to verify that. :-) Dismas|^(talk) 15:35, 7 July 2007 (UTC)[reply]

The thing about donner meat is that you can never be entirely sure by look and taste what manner of flesh you are consuming - it's just, well, slabs of 'generic meat'. Still, it tastes good when you're drunk and it doesn't poison you - so you don't say anything. --Kurt Shaped Box 21:57, 7 July 2007 (UTC)[reply]

Thanks for the tip, Nimur. I don't know what type of olives I had on the pizza but the ones I tried to eat by themself were from a jar of 'black olives in brine' from the supermarket (no other information specified). Yes, they did taste like how vulcanized rubber smells. --Kurt Shaped Box 22:02, 7 July 2007 (UTC)[reply]

Personally, I'd blame the brine, which probably contributed as much to the flavour as the olives themselves. Confusing Manifestation 09:35, 8 July 2007 (UTC)[reply]

This is a common phenomenon, strong flavors are often nasty by themselves, but help to improve the flavor of a meal, once diluted by the rest. Garlic would be another example, not many people enjoy eating garlic cloves straight, but many like a bit added to their meal (excluding vampires, of course). StuRat 07:10, 10 July 2007 (UTC)[reply]

RNA/DNA pills

Browsing a local bulk food and health food store, I came to find the vitamin aisle. I was looking to buy a daily vitamin, but a bottle caught my eye. I didn't buy it, nor did I want to/do I think I have a need for it. Out of curiosity, what benefit would it be for someone to take a supplement pill containing DNA and RNA of some random animal or plant? Vitamins and minerals and what not are in foods and other vitamin pills, so what good is the DNA of some other organism? 74.102.89.241 01:08, 7 July 2007 (UTC)[reply]

It's not going to be bad for you (we eat DNA & RNA in, well, basically everything.), but a pill of nucleic acids is wasted money. Completely. — Scientizzle 02:26, 7 July 2007 (UTC)[reply]

Yep - that's a scam for sure. Every cell of every living thing contains DNA and RNA - every plant or animal you eat (which is indeed pretty much everything) is stuffed full of the stuff. So this stuff is just a scam. They can get away with this because 'food supplements' are not vetted by government agencies like drugs - and notably there is no requirement for them to actually do what they claim to do. SteveBaker 03:01, 7 July 2007 (UTC)[reply]

Now you might think, we need more DNA and RNA "building blocks" all the time, for all the new nuclei in all the cells of ours that are dividing, and all the RNA that's being used in expressing metabolic reactions. And you might think, what better place to get those necessary building blocks than from a jar specifically full of the stuff?

However, if you're building new DNA, the essential building blocks are not adenine, guanine, cytosine, and thymine, but rather, carbon, hydrogen, oxygen, and nitrogen -- and we can, of course, get those raw materials from anywhere. [Well, okay, it's not quite that simple, because of course we can't fix our own nitrogen, but the point remains, we construct new DNA from generic organic building materials, not DNA-specific building materials.] —Steve Summit (talk) 03:53, 7 July 2007 (UTC) [augmented 03:58, 7 July 2007 (UTC)][reply]

We don't digest nucleic acids down into the constituent atoms and build them back up when we need them, it is possible for the body to absorb those water-soluble molecules. Also, keep in mind, the molecules used in DNA are also used in other organic reactions in the body. For example, Adenosine is used in nearly every energy transfer cycle your body uses to convert fuel into energy. -- JSBillings 12:26, 7 July 2007 (UTC)[reply]

That adenine used to be considered "vitamin B4" is new and interesting to me... — Scientizzle 05:08, 7 July 2007 (UTC)[reply]

last time I checked,mammalian red blood cells did not contain any DNA . Was my geneticist/proffessor wrong? Rana sylvatica 02:00, 13 July 2007 (UTC)Rana sylvatica[reply]

Yes, mammalian erythrocytes are anucleate and have no DNA. — Scientizzle 02:06, 13 July 2007 (UTC)[reply]

preventing pregnancy

Last night i made a sex with my girl friend using a condom. However, the condom ruptured while we made sex. We don't have a plan to have a child at this time. What we have to do now inorder to prevent the pregnancy?

Go see a doctor, he'll probably prescribe a morning after pill. - Dammit 07:29, 7 July 2007 (UTC)[reply]

And after that, review condom handling instructions. Generally speaking condoms should not break very often if used correctly. --24.147.86.187 11:39, 7 July 2007 (UTC)[reply]

That's wise advice - but to emphasise, they DO break occasionally even when used correctly. Our article on the condom says that even if you use them correctly, you still have a 2% per year chance of getting pregnant - and if you don't use them right, the chance is 10 to 18% which is definitely getting a little high! For the "Morning After" pill to work, you need to get to a doctor fast - you don't literally have to get there the next morning - but 72 hours is the utter, utter limit beyond which the doctor should not prescribe them. SteveBaker 13:55, 7 July 2007 (UTC)[reply]

But those are statistics over the whole population, and don't tell you about individual odds at all. If you use them right and they are not, say, out of date, then you should have almost no chance for pregnancy at all. A few people who use them wrong and etc. throws the whole sample off. --24.147.86.187 15:25, 7 July 2007 (UTC)[reply]

Those stats are probably based on a very large study group. So how would "a few people" throw the data off that much? Dismas|^(talk) 15:32, 7 July 2007 (UTC)[reply]

It's hard to see how a few people can cause a 10% to 18% change in the results - wouldn't that have to be 10% to 18% of the people surveyed? If you only surveyed 30 people - then three of them ('a few') could throw it off - but if you surveyed 3000 people then between 300 and 500 would have to have had condom failures in order to get this result - I don't think you can call 300 people "a few" in any reasonable version of reality! SteveBaker 03:32, 9 July 2007 (UTC)[reply]

Note that the 2% (for "perfect" use) pregnancy rate doesn't have anything to do with failure or misuse of the condom - I recommend you read the article - paying special attention to the Condom#Causes of failure section. This has nothing to do with a few misusers spoiling the sample - it's just a fact of the way these things work. Anyone using condoms for regular sex needs to be well aware that they don't work 100% of the time. SteveBaker 20:15, 7 July 2007 (UTC)[reply]

Vegetarian vs Non-Vegetarian

I have always had this doubt.....People who prefer Non-Vegetarian, are more physically fit, healthy and stronger than people who go for Vegetarian. Is it True ?

With a balanced diet, I don't see how there would be any difference between a vegetarian and non-vegetarian diet. As a matter of fact because vegetarians are more conscious of what they eat and more concerned about their health I think the "average" vegetarian would be more physically fit than the "average" omnivorous people. --antilived^{T | C | G} 10:25, 7 July 2007 (UTC)[reply]

Several studies have suggested that vegetarians are healthier. See vegetarian nutrition for more details.--Shantavira|^{feed me} 14:25, 7 July 2007 (UTC)[reply]

Heavyweight boxer Peter Hussing is said to have been vegetarian, as well as football legend Stanley Matthews. Unfortunately we don't seem to have a list of famous vegetarians, though we do have a list of vegans which includes several athletes.--Shantavira|^{feed me} 14:34, 7 July 2007 (UTC)[reply]

And there are so many versions of vegetarianism, it can be hard to make a direct side-by-side comparison. Nimur 15:50, 7 July 2007 (UTC)[reply]

All of the vegetarians I know are so skinny they look like ethiopians. I think vegetarians tend to be less healthy because it is harder to organize a healthy vegetarian diet compared to eating meat and people don't do it right, but if done right it can be more healthy.

Wrong. Vegetarians actually care about their diets, compared to the average meat eater who will shove down whatever they see --_ʇuǝɯɯoɔɐqǝɟ

It's more like the average eater period, not the average meat eater. By restricting one's diet one by nature has some care of what one eats. Someguy1221 06:51, 8 July 2007 (UTC)[reply]

Like all diets, a vegetarian diet can be harmful if one does not receive adequate nutrition from it. Many prominent examples show that one can be healthy and eat a strictly vegetarian diet. However, the more one restricts what one will eat, the more likely that nutritional deficits will develop if one is not mindful to such things. This is true for both vegetarians and omnivores (imagine eating nothing but red meat!). There are common potential problem with vegetarian nutrition, such as deficiencies in vitamin B12 or copper, that can be managed either with supplements or explicitly eating plants rich in those nutrients. Our article on veganism, for example, has a large section of precautions for managing such risks. In extreme cases, people have been convicted of child abuse for forcing highly restricted diets on children without concern for the resulting nutritional deficits. So, like many things, a vegetarian diet can be healthy or not depending on how it managed and the details of what one is eating. Dragons flight 20:11, 7 July 2007 (UTC)[reply]

Exactly. Vegetarianism is just as healthy as eating meat- which is, if you're reckless, you will hurt yourself. --_ʇuǝɯɯoɔɐqǝɟ 20:19, 7 July 2007 (UTC)[reply]

So why? statiscally, do veg heads live shorter lifespans than us omnivores? Might it be that they worry too much? Sorry if I offend, just curious. Rana sylvatica 02:09, 13 July 2007 (UTC)Rana sylvatica[reply]

Contrasting Colour Pallette

I have posted this on the Computer reference desk, but I'd like to see what the science-people think...
I am looking for a palette of colours (preferably with their hex codes (eg. 0xFFFFFF)) and they must be CONTRASTING COLOURS so that users can easily distinguish between them.
The highest number of colours I could get was 16 here: List_of_palettes#Microsoft_Windows_default_16-color_palette
I will be using thse colours in a chart, and I need the viewer to be easily able to distinguish the colours. Rfwoolf 16:03, 7 July 2007 (UTC)[reply]

Web colors might be useful. --jpgordon^∇∆∇∆ 17:16, 7 July 2007 (UTC)[reply]

You can do this mathematically. If you pick any really bright/vivid colour, and you have the hex representation, you can find the most contrasting colour very easily: Take the six digits in the hex code - break them up into three groups of two digits - then subtract each of the three resulting hex numbers from 0xFF (if you don't have a calculator that can do hex - you might want to convert to decimal notation first!). The result will be the complementary colour. sandwitch Hence, if you take a bright green (0x00FF00) then the complement is 0xFF00FF - which is magenta. Of course for very subtle colours, such as a very subtle green (0x7F8F7F perhaps), you'll get a very subtle pink (0x807080) as the complement which won't be easy for users to distinguish. For very dark green (0x002000 maybe), you'll get a very bright colour as the complement (0xFFDFFF). SteveBaker 20:09, 7 July 2007 (UTC)[reply]

Effects of electricity and magnetism on humans

Are there any known effects that electricity and magnetism may have on human beings' bodies? I've read that magnetism doesn't have any effects on a person, but maybe electricity does? Does it cause cancer or does it have any other effects? Has there ever been any scientific proof of this? ► Adriaan90 ( Talk ♥ Contribs ) ♪♫ 16:58, 7 July 2007 (UTC)[reply]

Well, I'm assuming you mean an electric field? Because there are a lot of ways you could interpret "effect of electricity" if you aren't specific! (Toaster in a bathtub?) --24.147.86.187 17:07, 7 July 2007 (UTC)[reply]

The effects can be shocking. --Tbeatty 17:17, 7 July 2007 (UTC)[reply]

Electric currents, whether direct current, alternating current or radio frequency current passing through human beings can cause burns, can cause traumatic effects on the functioning of the brain (as in electroshock therapy) and can cause death by stopping the heart. It only takes a few milliamperes to cause pain,and a little more can cause the muscles of the hand to contract on a wire and be unable to let go. Magnetic effects on the body are harder to prove. In MRI scans the human body is exposed to extraordinarily high magnetic fields without apparent effects, although there have been some studies which showed effects of magnitic stimulation of the brain on mental states such as depression. For decades there have been assertions that much weaker magnetic and/or electric fields from power lines and from wiring and appliances in the home cause cancer. These effects cannot be immediately and directly demonstrated in the laboratory (in the same way that electric shock can be immediately demonstrated to have an effect). They require large databases looking statistically at whether the rare occurrence of cancer is statistically related to exposure to electromagnetic fields (EMF). The results have sometimes come down as a slight tendency for EMF to cause cancer, and other equally careful studies have found no effect. Several public utility commissions have adopted a philosophy of "prudent avoidance ," which calls for avoiding unnecessary exposure to large EMF, by such means as routing a power distribution line so it does not go next to a school building, when another route is available. This policy in the absence of sound scientific proof of a link between cancer and EMF has been criticized as a waste of resources which could be spent in other ways to reduce illness.[1] If 100 studies are done to see if there is a statistical relationship between X and Y, 5 of the studies should find a significant effect at the usual .05 level, just because of random variation. The evidence is still only suggestive of a link [2] [3] [4] , but evidence suggests a biological effect of powerline frequence EMF or radio frequency EMF is quite possible [5] [6] , that prudent avoidance is justified, and that more research is needed. There should not be any supposition that EMF is the only cancer causing agent, and it should not receive an unjustified portion of public health funding, since exposure to sunlight and pollutants in air, food and water probably cause far more, and failure to use seat belts causes far more deaths per year. In recent years there has also been concern about Mobile phone radiation and health. Clearly there is nothing like the strength of association between Xrays and cancer, or smoking and cancer, or sunlight exposure and cancer. Edison 17:21, 7 July 2007 (UTC)[reply]

I agree with Edison - there are a bazillion problems with electric fields and essentially zero with magnetic fields. Just one little addition to that - there was a piece on Mythbusters (gotta love that show for all it's flaws!) that mentioned that old-fashioned tattoos were done with iron-based pigments and that the intense magnetic fields gemerated by an MRI machine could cause a tremendous amount of heating in the ink causing severe burns and such. Modern tattoos generally don't have that problem. SteveBaker 19:59, 7 July 2007 (UTC)[reply]

See Transcranial magnetic stimulation for the effect of magnetism on the brain. --Heron 20:34, 7 July 2007 (UTC)[reply]

Hey, thanks a lot for all your help. If you have anything to add, please do so! I appreciate all of your help. ► Adriaan90 ( Talk ♥ Contribs ) ♪♫ 21:32, 7 July 2007 (UTC)[reply]

There's also this Microwave Auditory Effect, which I believe may be dubious. However, academic peer reviewed papers have investigated it, and an earlier Science Reference Desk query suggested that high intensity electromagnetic waves might have unusual effects. You can also see Active Denial System for a less-lethal electromagnetic weapon. Nimur 03:37, 8 July 2007 (UTC)[reply]

I find it interesting that there are a "bazillion problems with electric fields and essentially zero with magnetic fields" when either can induce the other... Aaadddaaammm 04:38, 8 July 2007 (UTC)[reply]

Or more accurately a change in each can induce the other. You could also always consider getting hit by a laser beam an effect of electricity and magnetism. Someguy1221 06:10, 8 July 2007 (UTC)[reply]

history of emission control standards in automobiles

can i get the details of the various emission control standards set up worldwide chronologically and the organisations which ensure their implementationDeepu rdy 19:28, 7 July 2007 (UTC)[reply]

One is the Kyoto Protocol. The Clean Air Acts in various countries also qualify. See Emission standard for more info. StuRat 06:55, 10 July 2007 (UTC)[reply]

Voltage drop

I was debugging the network of electric cables in an old caravan and started to wonder if the voltage drops I seemed to have in the cables were reasonable. For example, there is one set of six lights in parallel, using about $5\,\mathrm {W}$ of power each. I connected this set to the $12\,\mathrm {V}$ battery that powers it all, and found that the battery voltage settled on $12.1\,\mathrm {V}$ . Then I measured the voltage over one of the lights and got only $8.5\,\mathrm {V}$ . :-( Isn't this difference quite large? —Bromskloss 20:07, 7 July 2007 (UTC)[reply]

Yes. Your cables are too thin. You are losing nearly 9 watts in them! --Heron 20:26, 7 July 2007 (UTC)[reply]

You're right. :-( Is it likely that connections between cables degrade over time (or never were any good) with a large resistance as a consequence? —Bromskloss 20:41, 7 July 2007 (UTC)[reply]

That's seems an awfully large drop. If that's true - then you should be able to feel the wires getting warm. But yeah - car lamps do pull quite a bit of current - so heavy wires are required. SteveBaker 20:50, 7 July 2007 (UTC)[reply]

It is very likely that the connections do degrade over time and Ill bet that that is where most of your power is being disippated. My advice: clean up/ replace all connectors for full lamp briteness!--Tugjob 22:47, 7 July 2007 (UTC)[reply]

If you do the math, the resistance of your cable+connection is 2 ohms. The lights in parallel are about 4 ohms (28 ohms each). --Tbeatty 15:29, 8 July 2007 (UTC)[reply]

The voltage drop sounds way too high, if the battery was in fact still putting out 12 volts. In an old rustbucket car the ground connection from a light can also corrode and cause a voltage drop. It is common to carry wires from the battery positive through switches to a terminal of a bulb, and to achieve the other battery connection through the car body. If there is a lot of rust around the light, the resistance may be in the negative return path. On really old cars, the polarity was sometimes reversed. A supplemental ground connection can sometimes help. In troubleshooting, you can also start at the bulb terminal where you see 8.5 volts to the battery negative, and check the voltage at points further back (closer to the battery positive) to see where the voltage drop is. Of course you should not tinker with electricity unless you are fully conversant with safety procedures. Edison 19:06, 8 July 2007 (UTC)[reply]