Wikipedia:Reference desk/Archives/Science/2010 June 2

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June 2

Decaffeinated coffee acclimatisation

Can decaffeinated coffee still have an effect, whether placebo or directly? I mean, clearly it contains nothing to compete with adenosine so it can't work the same way, and I'm skeptical, but decaffeinated coffee definitely has an effect on my personal sleeping habits. Why would this be? How? Regards, --—Cyclonenim | Chat  00:36, 2 June 2010 (UTC)

One thing to keep in mind is that decaffeinated coffee may still contain clinically significant amounts of caffeine. I suspect this is especially true for higher-quality blends, where the priority is flavor rather than removing all the caffeine you possibly can, but I don't really know that. --Trovatore (talk) 00:46, 2 June 2010 (UTC)

Decaffeinated does not mean caffeine free. --Chemicalinterest (talk) 00:59, 2 June 2010 (UTC)

I would be quite surprised if there wasn't a placebo effect, but generally that would require the drinker to think they were drinking regular coffee. I'm guessing that isn't the case with you, so it is unlikely to be placebo. It could just be confirmation bias, though. Alternatively, Trovatore may be right and the small amounts of caffeine still in the coffee are having the effect. --Tango (talk) 01:08, 2 June 2010 (UTC)

Our article on decaffeination makes reference to an "international standard" that 97% of the caffeine must have been removed, and to an "EU standard" that the beans must be 99.9% caffeine-free. On the other hand, one of the references is to this Science Daily article, which implies that decaf may have as much as 20% of the caffeine of regular coffee.

These facts seem somewhat difficult to reconcile. One possibility is that the coffee referred to by ScienceDaily was not compliant with either of these standards. Another is that beans consisting of 0.1% caffeine by weight (how much is in normal beans?) still produce coffee with 20% the caffeine of regular (maybe in part because you need more coffee grounds to get the same concentration of flavor chemicals?). --Trovatore (talk) 01:40, 2 June 2010 (UTC)

The amount of caffeine is strongly influenced by brewing method, so it's difficult to make good comparisons. Ariel. (talk) 03:40, 2 June 2010 (UTC)

Original research: When I drink a carbonated beverage, I instantly feel a buzz whether or not it has caffeine; I have to think this is some sort of placebo effect my brain is pulling on me (unless it's the carbonation itself). -RunningOnBrains^(talk) 05:25, 2 June 2010 (UTC)

I'd guess it's the sugar giving you the buzz. --Tango (talk) 11:00, 2 June 2010 (UTC)

Can you even get a placebo effect if you know it is a placebo? Googlemeister (talk) 13:47, 2 June 2010 (UTC)

Maybe with a bit of doublethink! --Tango (talk) 16:16, 2 June 2010 (UTC)

Still has caffeine, but maybe similar chemicals (take one or two methyl groups off) also give insomnia. That rooibos tea and chicory root is caffeine free but still has other stimulants. Polypipe Wrangler (talk) 13:40, 2 June 2010 (UTC)

Thanks for the responses :) Regards, --—Cyclonenim | Chat  17:05, 2 June 2010 (UTC)

Different kinds of cold?

Why is it that I could stand cold weather or the temperature in Baguio City but shiver when near an air conditioning unit? Do outside weather and air conditioning cools us differently?--Lenticel ^(talk) 02:12, 2 June 2010 (UTC)

For one thing, the air conditioner is probably blowing the air at you. Moving air will almost always "feel" colder than standing air. (See Wind chill for an extreme example of this). Buddy431 (talk) 02:39, 2 June 2010 (UTC)

One thought is that usually when you're outside you're not just hanging out, you're doing something even if it's only walking from place to place. Inside you're liking to be sitting in a chair and not exerting yourself. APL (talk) 04:17, 2 June 2010 (UTC)

Unfortunately, Thermoception is not a very good article, but that may be what you're looking for. We don't typically feel absolute hot and cold, just relative temperatures, so if you put one hand in hot water, another in cold water, and then put both in lukewarm water, the lukewarm water would feel hot to the hand that was in cold water, and vice versa. If you're air conditioning is much cooler. Also, you likely wear warm clothes outside in the cold, but not inside in your air conditioning. Furthermore, forgive a little teasing, but "cold" in Baguio City (record low: 46 °F (7.8 °C)) isn't exactly the same as the "cold" I know (record low: −24 °F (−31 °C)) -RunningOnBrains^(talk) 05:22, 2 June 2010 (UTC)

Dude, I live in the hot and humid tropics, so that's already cold :)--Lenticel ^(talk) 00:55, 3 June 2010 (UTC)

46 °F (7.8 °C)!?? Haha. I still wear shorts and a t-shirt in that kind of weather if there's not too windy! (admittedly, some neighbors think I'm crazy.)

Actually, the air coming out of your air conditioner could literally be colder than that. (Sure, your thermostat is set to something reasonable, but to achieve that it needs to mix some really cold air into your hot home.) APL (talk) 06:12, 2 June 2010 (UTC)

Air conditioners don't just cool the air, they also dry it, which makes it cool your skin more via evaporation. Since Baguio City, at an altitude of a mile above sea level in the Philippines, must be one of the most humid places on Earth, it can make a big difference. Looie496 (talk) 16:37, 2 June 2010 (UTC)

Humidity. Ah that's must be it! I mean the air is still humid even during the El Nino season. --Lenticel ^(talk) 01:22, 3 June 2010 (UTC)

"Dirty dozen" fruits and vegetables

CNN.com has an article on fruits and vegetables that contain pesticides even after being washed. The article has a "dirty dozen" list and a "clean 15" list of produce. What is confusing is that while potatoes and lettuce are on the dirty list, sweet potatoes and cabbage are on the clean list. Why? There seems to be no simple rules of thumb that can help you figure out for what produce you should go organic. --173.49.15.136 (talk) 02:40, 2 June 2010 (UTC)

My guess would be the susceptibility of the plant to damaging insect invasion leads to the use of insecticide. Bus stop (talk) 03:05, 2 June 2010 (UTC)

For sweet potatos, they may be assuming that people aren't going to eat the skin. That's what appears to separaten the clean vs. dirty foods to a large extent: whether people eat the outside layer. I like how they emphasize the number of different types of pesticides in the different types of produce. Wouldn't make more sense to look at the total amounts of pesticides, rather than the variety? Buddy431 (talk) 03:17, 2 June 2010 (UTC)

"Give me spots on my apples; But leave me the birds and the bees" (Joni Mitchell — Big Yellow Taxi) Bus stop (talk) 03:22, 2 June 2010 (UTC)

Who is applying so many different types of pesticide on the one foodstuff? I find it hard to believe that some foodstuffs contain up to 67 different pesticides. Caesar's Daddy (talk) 07:32, 2 June 2010 (UTC)

A lot of it's probably contamination from other types of produce grown nearby; a good wind and you've got on your plant whatever your neighbor put on his. Still, 47-67 different pesticides does seem pretty excessive. Is there anyone here with experience in this type of thing who can explain how, and how many, pesticides are typically applied to different types of food? Buddy431 (talk) 16:34, 2 June 2010 (UTC)

A "single" pesticide, may actually be a combination of multiple chemicals. Like how with roundup the article mentions how roundup itself is pretty safe, but it's extensive list of additives are the problem. It doesn't say how many it has, but if other pesticides are like that, that could easily increase the number. Just a guess. Ariel. (talk) 18:53, 2 June 2010 (UTC)

Terraformation of Mars

In this picture, they show an artists conception of the terraformation of mars. In stages 3 and 4, they basically just add more water, making the oceans bigger. What exactly is the advantage of that? Wouldn't it be better to have more land than oceans? ScienceApe (talk) 03:42, 2 June 2010 (UTC)

Perhaps because oceans might help regulate the Martian climate better Ocean#Climate_effects.--Lenticel ^(talk) 03:47, 2 June 2010 (UTC)

Water is also the most important greenhouse gas on Earth, and given how cold Mars is, covering a larger surface area with standing water might contribute to getting more water into the air to help support this warming. (Of course to get an ocean in the first place you already have to add something to the atmosphere to trap heat and keep the water from simply freezing.) Dragons flight (talk) 03:53, 2 June 2010 (UTC)

There are several reasons to have an ocean. First, the above-mentioned greenhouse effect. Second, water has a very high specific heat capacity, and because it is mostly transparent, serves as a giant heat sink, which keeps the earth's temperatures from fluctuating too much over the course of a day (currently, martian temperatures can change almost 100 °C (180 °F) in a day). Thirdly, if you hope to terraform a planet, and introduce large amounts of life, you're going to need large amounts of water.

Unfortunately, terraforming Mars is unlikely to work. Mars' low mass means that, unlike on earth, important molecules such as nitrogen, oxygen, and, yes, water vapor can escape its gravity directly into space over time. Thus, we would need to constantly replenish any atmosphere we created there. This is of course ignoring the HUGE question of "where the heck to we get a planet's supply of water and oxygen from in the first place?" :-D -RunningOnBrains^(talk) 05:08, 2 June 2010 (UTC)

Atmosphere loss is only significant on a geological time scale. Unless the teraforming is planned to take billions of years, replenishing the atmosphere would be trivial compared to the task of creating one in the first place. --Bowlhover (talk) 08:11, 2 June 2010 (UTC)

To get the water there in the first place (assuming we don't find enough frozen down under the surface already) would probably require bombarding the planet with icy asteroids - no small feat! The whole issue is really about how to warm the planet up - doing that would make it possible to drive water and various gasses out of the soil. There is a lot of frozen CO2 at the poles, melting the icecaps could liberate that and cause enough of a global warming effect to heat up everything else. Once things are warm and there is a denser atmosphere (albeit mostly of CO2) then you'd want to add photosynthesis to the mix to turn CO2 into oxygen. But this is a crazily difficult project. Nobody should ever underestimate the difficulties. SteveBaker (talk) 11:53, 2 June 2010 (UTC)

Indeed, it is beyond our ability to really conceive of how it would be done. It's not going to be done in the next 25 years, and as far as technology is concerned any predictions more than 25 years ahead are little more than guesses. --Tango (talk) 16:18, 2 June 2010 (UTC)

There are arguments that the bulk of Mars' former atmosphere has not been lost to space, but rather has become locked up in its rocks because, unlike on the Earth, it does not get recycled by tectonic activity and active vulcanism. Theorists such as Martyn J. Fogg (a personal acquaintance) have proposed releasing significant quantities from appropriate strata by large scale thermonuclear engineering (i.e. bury huge H-bombs and set 'em off, preferably from a distance). Such released gasses might, by positive global warming feedback mechanisms similar to those we ourselves are arguably experiencing, cause further atmospheric evolution and result in a useful atmosphere quite rapidly, which might persist on a timescale of the order of 100,000 years or more before further replenishment became necessary. 87.81.230.195 (talk) 22:09, 2 June 2010 (UTC)

I was under the impression that lack of a magnetosphere was a (the?) reason Mars doesn't have an atmosphere. From the magnetosphere article: "Earth’s magnetosphere provides protection, without which life as we know it could not survive. Mars, with little or no magnetic field is thought to have lost much of its former oceans and atmosphere to space in part due to the direct impact of the solar wind." How this would play out in human timescales with respect to terraforming, I have no idea. --- Medical geneticist (talk) 22:58, 2 June 2010 (UTC)

On human timescales, it would have very little effect. The Earth effectively loses its magnetic field for a few years every few tens of thousands of years (see Geomagnetic reversal) and our atmosphere doesn't disappear. On geological timescales, it could easily have a very significant effect and may well be the leading reason for Mars not having a thick atmosphere now. --Tango (talk) 16:21, 3 June 2010 (UTC)

"This is of course ignoring the HUGE question of "where the heck to we get a planet's supply of water and oxygen from in the first place?"" -- Isn't there already a "planet's supply of water" frozen in the Martian polar ice caps? 67.170.215.166 (talk) 05:25, 4 June 2010 (UTC)

I think the supply of water is presumed to be coming from the asteroid belt and from comets, where some sort of renewed "bombardment" of the surface of Mars would happen to quickly place that water on Mars... especially while it is mostly uninhabited. A good description of how this would happen can be found in the Mars trilogy of books written by Kim Stanley Robinson. While certainly these books are works of fiction, they do provide real scientific thought on the topic including several competing methods for adding some bulk to the atmosphere. That really is the big issue, as once there is some bulk to the atmosphere you can then use plants and some bio-engineering to convert CO2 to water and other compounds needed for life. If you haven't read these books but are interested in Martian terraforming, these are simply must-read books... at least to carry on intelligent conversations with others who are discussing this concept.

Something else to consider is the Gaia hypothesis, where perhaps the introduction of living things on Mars would also sort of help to also foster an environment that would be favorable to other living things. I admit this is incredibly controversial and its application to terraforming is even more controversial still, but it is at least something to look at. It isn't entirely clear that Mars is completely without life either, although the conditions that Martian life forms are living under would be obviously different than what we find on the Earth and would be more like extremophiles if any are actually found. --Robert Horning (talk) 01:33, 6 June 2010 (UTC)

How much water Mars still has is subject to HUGE debate...but I don't think anyone would argue that there is enough to produce the picture above...especially if you are going to be using this water as a source for your oxygen (of which there is practically zero in Mars' atmosphere currently).

The "ice" caps are mostly frozen carbon dioxide, and they "melt" substantially every summer (CO2 does not melt but sublimates, or turns directly into gas).-RunningOnBrains^(talk) 20:19, 6 June 2010 (UTC)

Why use the water as a source of oxygen, when we could introduce some blue-green algae into the water and use them to turn the CO₂ in the atmosphere to oxygen? 67.170.215.166 (talk) 00:39, 7 June 2010 (UTC)

I believe there is oxygen contained in the molecules that make up the crust of the planet. ScienceApe (talk) 02:22, 7 June 2010 (UTC)

Well, if you use CO2 from the atmosphere, you are still left with an atmospheric pressure that is too low to comfortably support life. -RunningOnBrains^(talk) 15:16, 7 June 2010 (UTC)

To clear up a possible misconception, Photosynthesis#Light reactions, including those of blue-green algae, obtain the oxygen from water and not from carbon dioxide. -84user (talk) 18:33, 7 June 2010 (UTC)

Linde's chaotic inflation: why only one level of bubble universes?

Andrei Linde's theory of bubble universes (I don't know if "bubble universe" is the acccepted term, but you know what I mean) describes them as emerging from an ur-universe (again, I don't know the accepted term). However, from what I can find on wikipedia, Linde's theory doesn't describe bubble universes emerging FROM the first "level" of bubble universes (The "level" emerging from the ur-universe); and the previous statement can be extended to bubble universes emerging from the bubble universes that emerge from the bubble universes that emerge from the ur-universe. In other words, Linde's description seems to involve only one "level" of bubble universes.

However, theoretically, bubble universes could emerge from within THIS ("our") universe, which implies at least one more "level" of bubble universes.

Have I misunderstood Linde's description? Or, perhaps, are further "levels" implied by Linde, but he leaves the implication unstated in order to simplify his description? Have others theorized further "levels"? If so, have they described this as being different from Linde's description, or just a corollary to it? 63.17.75.70 (talk) 04:04, 2 June 2010 (UTC)

In the more esoteric but serious sciences called cosmology and superstring theory, there are many theories of bubble universes, these theories sometimes overlap. For a popular science sampling, you could search for "bubble universe" at www.newscientist.com. It's one of their favourite topics, with repeated coverage. From what I've seen, most such theories imply sometimes a chain of bubble universes of unspecified length, towards both the past and the future, and sometimes that our universe bubbled forth from something "simpler" like some kind of vacuum that's not a typical universe in its own right. Sometimes the future bubbling out of our universe involves black holes, sometimes something catastrophic happening to the vacuum energy. It's all theory and you can really pick and choose. EverGreg (talk) 12:07, 2 June 2010 (UTC)

The diagram I saw (colloquium by someone... perhaps a former student of Linde?) showed sub-universes forming in a sort of bifurcation pattern, so that, if I understand your question right, this universe may already be seeding other universes, but obviously we don't see it (the bubbles form outside our dimensions). That would describe many layers of bubbles. The bifurcation diagram in chaos theory is a nice illustration, though the chaos cutoff doesn't occur I don't think. SamuelRiv (talk) 18:09, 2 June 2010 (UTC)

Thanks -- although I asked a sub-question about "corollaries" and the like, my question is about Linde, specifically. Does his theory describe only one "level" of bubble universes (each one emerging from the ur-universe, and none in turn creating new bubble universes)? That's how it seems to me, but I can't understand why he would stop at one "level." 63.17.89.8 (talk) 02:19, 3 June 2010 (UTC)

Hi, I'm hoping to clarify - the lecture I saw was directly about these bubble universes, and distinctly showed multiple levels, if I understand your meaning correctly, in that our universe may be currently seeding many more universes. Incidentally, the model is very similar to that of a bubble, in which false vaccum (a nice positive energy state that's fairly stable and forms randomly) expands until it can't hold itself up, then either bursts (kaboom) or splits (or bifurcates) into smaller universes that repeat the process, such that there are presumably innumerable levels. SamuelRiv (talk) 02:31, 3 June 2010 (UTC)

As far as I know, in Linde's picture, the large flat regions (like the one we're in) are not chaotic enough to trigger further inflation. In other words, there's only one level. Other people (like Lee Smolin) have attached additional inflationary regions to black hole interiors, making for many levels. You shouldn't take any of this stuff very seriously, though. -- BenRG (talk) 09:35, 3 June 2010 (UTC)

BenRG -- thanks, that's exactly what I was looking for (does anybody else have more?). I disagree with you about not taking it seriously. THIS universe can (possibly) create bubble universes; therefore, it's reasonable (via avoiding anthropomorphic "specialness") to presume that this universe is in turn a bubble universe. Apparently, from what you've said, Linde either does not think that this universe can create bubble universes, or else did not describe such a model. 63.17.46.82 (talk) 04:40, 4 June 2010 (UTC)

Aha, it was Lee Smolin whom I saw give the lecture. I feel like a loser for not remembering, but I was a lowly sophomore at the time, and am not in cosmology. For what it's worth, I take it seriously - it's a very "philosophically comfortable" idea for me. And look... look - bear with me here - cosmology beyond the observable universe has to have a component of philosophical comfort, right? Comfort can certainly change with our changing perception of physics, but that is as much a basis for study as any, right? SamuelRiv (talk) 05:15, 4 June 2010 (UTC)

SamuelRiv, thanks for your responses -- they were useful, but (as you see) it was Linde I was after. But this does bring up another question (if anybody's listening): Lee Smolin wrote a book advocating (or maybe just describing the theory of?) "baby universes." Years later, in a celebrated comment, he said "This universe is the only one there is." I can't figure out if this means he abandoned the baby universe theory altogether, or if he was defining "universe" to mean "the universe that contains all the baby universes." Does anybody know how Smolin's two positions relate to each other? Also, again, I would appreciate more insight into Linde's position if anyone has any.63.17.83.221 (talk) 03:20, 5 June 2010 (UTC)

Lake Okeechobee

Is there any evidence such as shocked quartz, a gravity anomaly, and tektites in areas surrounding Lake Okeechobee in Florida, USA to suggest the lake might be the sight of an impact creator as far back as the end of the Cretaceous period? 71.100.8.229 (talk) 04:48, 2 June 2010 (UTC)

Lake Okeechobee hardly even exists, in a geological sense. It is 13 feet deep at its deepest point. There is a geologist named E. J. Petuch who suggested in the 1980s that the Everglades are the remnant of an ancient crater formed by a meteorite strike 38 million years ago, but he seems to have backed away from that idea, and I can't see any serious suggestions that apply to Okeechobee. The only thing in its favor is that it is sort of roundish. Looie496 (talk) 05:34, 2 June 2010 (UTC)

Reverse jet filter - pressure drop

Hi Can anyone tell me how to calculate the pressure drop in a reverse jet filter if I know the volume flow rate and dimensions of the filter bags, no and material of bags etc Thanks —Preceding unsigned comment added by 123.237.93.244 (talk) 05:36, 2 June 2010 (UTC)

Try Bernoulli's equation —Preceding unsigned comment added by 79.76.159.3 (talk) 09:21, 2 June 2010 (UTC)

Bernoulli's equation has a term for losses. It is that term which I am interested in. So if anybody has a model or correlation for obtaining the pressure loss in the reverse jet filter I will be grateful if you can share it. Thanks —Preceding unsigned comment added by 123.237.93.244 (talk) 09:44, 2 June 2010 (UTC)

What about this ref? [1] —Preceding unsigned comment added by 79.76.159.3 (talk) 23:50, 2 June 2010 (UTC)

mortality percent

What waist to hip or other body measurement ratio has the least percent of death for each age over 60 for males? 71.100.0.241 (talk) 08:50, 2 June 2010 (UTC)

Death is affected by many other factors, so hip measurement may only be a minor one. --Chemicalinterest (talk) 11:12, 2 June 2010 (UTC)

Yes, it is an indicator of heart disease and diabetes (fatter=more likely . suprised?) specifically it's relation in general to Body mass index eg very generalised or bmicalculate.net just google for "waste hip ratio +disease", and choose a disease.

Skinnys die too - and the percentage of death is close to 100% :)

Briefly covered at Waist-hip ratio there's a link in there too. 87.102.114.166 (talk) 12:29, 2 June 2010 (UTC)

LOL... the picture caught me by surprise... the article suggests that there is a correlation between WHR and offspring intelligence due possibly to more polyunsaturated fats the fetus needs for brain development. Maybe the real reason is that the fetus just wants to find ways to attract a mate with large quarters. :-] 71.100.0.241 (talk) 15:15, 2 June 2010 (UTC)

more[2] suggests 0.95 for men and 0.80 women is a good bet, these figures are for specific causes of death , this [3] for all causes of mortality death rate increases with waste to hip ratio.87.102.114.166 (talk) 13:11, 2 June 2010 (UTC)

This has some data. [4] I can't find the exact data you ask for.87.102.114.166 (talk) 14:18, 2 June 2010 (UTC)

This http://www.nhs.uk/chq/Pages/849.aspx?CategoryID=51&SubCategoryID=165 says your waist should be under 37 inches, for men. I would doubt there is a simple optimum - you should be slim but not literally starving, but sometimes becoming thin is a sign of having a serious illness rather than dieting, and this would distort the results upwards. 92.28.249.38 (talk) 14:38, 2 June 2010 (UTC)

Oxidation of copper by iron(III) chloride

When I placed copper in a solution of iron(III) chloride, the brownish yellow solution turned green. Is it due to this oxidation reaction: Cu + 2 FeCl₃ → CuCl₂ + 2 FeCl₂ Thank you. --Chemicalinterest (talk) 11:14, 2 June 2010 (UTC)

Think so Fe3/Fe2 standard potential is 0.77V , Cu2/Cu is 0.34V - the reaction would go, copper (II) chloride is green , ferrous chloride is pale. The potentials for chloride complexes are different, and I haven't bothered to find them since there's no big difference between copper and iron in this respect.87.102.114.166 (talk) 12:35, 2 June 2010 (UTC)

Or .. if you'd read Iron(III)_chloride#Industrial you'd have already seen the answer .. ... yes .. 87.102.114.166 (talk) 12:39, 2 June 2010 (UTC)

That's where I got my idea from; it was used as a copper etchant. It is unlike other metal-metal salt redox reactions in that another metal is not formed. I didn't see any copper(I) chloride intermediate like they stated in the article. --Chemicalinterest (talk) 13:33, 2 June 2010 (UTC)

I don't think the CuCl will be present in large amounts - it might not dissolve depending on the concentration of Cl- in solution. There might be some on the surface of the copper - eg use copper + FeCl3 dilute - remove the copper and wash the surface with (pure) water - a patina of CuCl (might) be present - any CuCl2 would be washed away by the water.

CuCl is white - not sure how to tell if it's in that solution (as CuCl2-) anyway. 87.102.114.166 (talk) 14:10, 2 June 2010 (UTC)

drug interaction checking

I perhaps did not make myself clear in a previous question regarding Phenylephrine, which is given to dilate pupils and has the side effect of restricting blood vessels and Simvastatin, which is given to reduce high Cholesterol which is the intended effect. Although there is no direct interaction between Phenylephrine and Simvastatin for a drug interaction checker to find it does not appear that any drug interaction checker will also look for the combination of blood vessel restriction from high Cholesterol and from the side effect of Phenylephrine which could be deadly. Is there a program or method which checks for these types of deadly interactions since drug interaction checkers appears to ignore such interactions? 71.100.0.241 (talk) 13:11, 2 June 2010 (UTC)

Why do you believe that they don't check for such interactions? 75.41.110.200 (talk) 15:12, 2 June 2010 (UTC)

Because I can find all sorts of drug interaction and WHR and BMI warning check sites on the Internet but not any that warn of this problem. 71.100.0.241 (talk) 16:49, 2 June 2010 (UTC)

Standard checks for phenylephrine show up various warnings and cautions for people with clogged veins etc [5] [6] [7] 87.102.114.166 (talk) 17:39, 2 June 2010 (UTC)

What makes you think that this is a problem? I mean, there could be drug-drug interactions between any combination of medicines, but why would you think that a "drug interaction checker" would look for a combination of phenylephrine and high cholesterol? It just doesn't make sense. We normally associate high cholesterol with atherosclerosis, which typically affects large blood vessels and is associated with acute blockages due to thrombosis. The mechanism of phenylephrine is completely different, as it acts primarily to constrict small blood vessels in the periphery. Can you cite any evidence to suggest that the combination of phenylephrine and "blood vessel restriction from high cholesterol" could be "deadly"? Perhaps the reason that the drug interaction checkers ignore this is that it doesn't exist? If this is something that you are truly concerned about, you need to ask your doctor about it. --- Medical geneticist (talk) 22:50, 2 June 2010 (UTC)

Remote sensing and GIS

1.Write the short notes in image enhancement techniques based on the followings;-

a)Constract stretch.

b)Image filtering.

c)Colour composing.

d)Vegitation index.

2.Write the short notes on digital image classification;-

a)Minimum distance classifier.

b)Box/parallelopipe classifier.

c)Maximum Lixelihood classifier. —Preceding unsigned comment added by Kamtwanje,Hussein George (talk • contribs) 16:01, 2 June 2010 (UTC)

Please do your own homework.

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.--Tagishsimon (talk) 16:04, 2 June 2010 (UTC)

Remote sensing and GIS might help. Pfly (talk) 16:04, 3 June 2010 (UTC)

History of Science: What did Islamic Science invent or discover?

Does anyone on Wikipedia, have a list of scientific discoveries that can be directly attributed to scientific researchers working in the Islamic world?

Sfan00 IMG (talk) 16:20, 2 June 2010 (UTC)

We have a very extensive article on that topic, inventions in medieval Islam. Looie496 (talk) 16:24, 2 June 2010 (UTC)

Also Timeline of science and engineering in the Islamic world for other periods.87.102.114.166 (talk) 16:45, 2 June 2010 (UTC)

Thanks, Both articles seem to have an extensive set of further sources as well :) Sfan00 IMG (talk) 17:06, 2 June 2010 (UTC)

Hmm, Reading that led me to a question on a tangent... Could the Islamic World have developed a self-contained powered vehicle before the Industrial Revolution in Western Europe? Sfan00 IMG (talk) 21:37, 2 June 2010 (UTC)

Hero invented a cart that moved around by itself, the path could be programmed by winding a string round pegs on a barrel. Dmcq (talk) 21:59, 2 June 2010 (UTC)

Shame it wasn't a 'turtle'.  ;) XD Sfan00 IMG (talk) 22:32, 2 June 2010 (UTC)

I assume this was Hero of Alexandria.

It's possible but not quite there..

• A steam engine - probably not able to make a boiler that withstood the pressures, and more importantly make pistons to the correct accuracy - but maybe they could have if they'd tried. Similar problem with internal combustion
• Electrical - this seems more likely - they almost certainly had the battery - I assume the knew about magnets - however I don't thing they had made the connection between electricity and magnetism necessary to - make big magnets, and make motors.

I'd be fascinated to be proved wrong.

Are there any other forms of propulsion.87.102.114.166 (talk) 22:18, 2 June 2010 (UTC)

I'm not entirly sure an Arab steam engine is as implausible as you suggest, given that 'distillation' was a chemistry technique discovered in the Arab world (and would thus have needed appropriate vessels).

The articles linked also note that there were automata that ran on steam so...

I'm not saying that the self propelled vehicle has to be 'useful' .. Sfan00 IMG (talk) 22:33, 2 June 2010 (UTC) Other forms of power... - Water... - Sand ... Clockwork mechanisms - Comments on the #wikipedia-en IRC suggested mechanical clockwork power needs a coil spring which would need a certain level of metalworking. That said, simple mechanical power storage like a twisted cord could be built on fairly simple technology...

Yes spring power - in medieval time they definately had the metal working skill to make steel suitable for springs - at least Damascus steel is getting near to a similar thing.83.100.183.63 (talk) 22:53, 2 June 2010 (UTC)

The thing here is that they didn't develop such a thing. Could they (hypothetically) have done? Well, no. After a burst of creativity and invention in the 9th to 12th centuries (roughly) - things pretty much shut down. Look at the list of inventions - hardly anything in the 15th century - pretty much nothing after that. What stopped them from inventing the car (or the bicycle for that matter) was what stopped them from progressing at all since then. What stopped them was largely societal - but that's every bit as much of a brake on progress as (say) inadequate understanding of mathematics stopped the Romans and lack of interest in experimentation stopped the Greeks. In the end, the only inventions that mattered in the western world was aggressive concentration on universal scientific education and the development of "The Scientific Method". SteveBaker (talk) 23:26, 2 June 2010 (UTC)

Whoa nelly, Steve! That's a bit of overt oversimplistic Eurocentricism, don't you think? The question of Enlightenment and Industrialization is extremely complex, and in the case of the former, it's to argue that the Hellenes or Islamic scholars were not as scientifically progressive during their prime as the Royal Society at their founding, say (especially since they didn't have the advantage of a bunch of infinite series and algebraic constructs already pre-written for them). Also, universal scientific education? Not until the mid-19th century. The Scientific Method? Not until the mid-19th century. At least, not in a more advanced state than aforementioned scholars. SamuelRiv (talk) 02:19, 3 June 2010 (UTC)

Not Eurocentricism so much as counting the number of entries in Timeline of science and engineering in the Islamic world for each century. You can do that for yourself - and I'm sure you'll come to the same conclusion that I did. If you look deeper, the situation is even worse than that. So many of the recent entries are the obscure and not-earth-shattering work of a single guy who either works in the west or was trained in western universities. Several of the 21st century breakthroughs are incredibly trivial inventions (a non-glare headlamp and an automatically raising ladder for chrissakes!) - these hardly rate up there with decoding the human genome, building the Internet, writing Wikipedia, flying to the moon, and other modern inventions. I know this sounds terribly non-politically-correct, but just read what the article says...it's undeniable. SteveBaker (talk) 15:06, 3 June 2010 (UTC)

The scientific method was adopted since the Scientific Revolution. Certainly by the 19th century, the accepted way of doing science was by experiment, not by endless philosophizing or appealing to religion. --Bowlhover (talk) 07:04, 3 June 2010 (UTC)

I just noticed the 16th C Taqi_al-Din_Muhammad_ibn_Ma'ruf#The_Sublime_Methods_of_Spiritual_Machines a description of a turbine and a reciprocating engine. I still haven't found evidence that they would have been able to make suitable high pressure cylinders or pistons though.. I think a key technology here is the Lathe for metalworking but I can't find much about this aspect (they had lathes for lenses though) 83.100.183.63 (talk) 11:34, 3 June 2010 (UTC)

One of the biggest issues for the slowdown was that while a lot of the basic science was developed by the end of the 16th Century actually exploiting it to make significant further developments needed an increasingly industrial economy. That required access to suitable raw materials in significant volumes and access to significant workforce.

That didn't really start to kick in until the late 17th Century in Europe. The basic science was essential to the industrial revolution, but building on the basic science wasn't really an option in North Africa and Persia.

ALR (talk) 15:57, 3 June 2010 (UTC)

The Industrial Revolution article does list theories for why it occurred where and when it did. Most of the sociocultural arguments I believe are bunk (Christianity encouraging belief in rational laws?). The most convincing argument I have seen, in contrast to what ALR says above, is in comparative popular history, which set a standard of per-capita income. In all major advanced societies - Rome, the Ottomans, Tang China, and possibly others depending on the analysis - while productivity and scientific advancement were enormous, there were essentially too many poor people providing too much cheap labor to make machinery a worthwhile investment as it was in 1800 England.

Bowlhover-"the accepted way of doing science was by experiment, not by endless philosophizing or appealing to religion" - tell that to Ptolemy or Archimedes or Galileo or Boyle, if we only want to stay in the Western Hemisphere. Conversely, tell it to Faraday or the anti-positivist Maxwell. SamuelRiv (talk) 16:00, 3 June 2010 (UTC)

Hmmm ? Maybe I misunderstand your point, but Galileo Galilei, Robert Boyle and Michael Faraday are well known as experimentalists. Gandalf61 (talk) 08:57, 4 June 2010 (UTC)

See also Al-Jazari#Mechanisms and methods.Email4mobile (talk) 15:12, 6 June 2010 (UTC)

And Taqi_al-Din_Muhammad_ibn_Ma'ruf#Mechanical_treatises section which describes his invention of an early practical steam turbine.--Email4mobile (talk) 15:42, 6 June 2010 (UTC)

Same thing that Hero of Alexandria did in the 1st century BC. (I wonder if this might have been a case of patent infringement?) 67.170.215.166 (talk) 00:42, 7 June 2010 (UTC)

The patent would have probably expired by then. Googlemeister (talk) 14:07, 7 June 2010 (UTC)

density of liquid mixture

i would like to know how do we calculate the density of liquid mixture.for eg how do i calculate density of 40 % ethanol v/v?we know the density of absolute ethanol and that of water but how do we apply this knowledge to calculate density of the mixture?please guide. —Preceding unsigned comment added by 180.149.53.9 (talk) 19:40, 2 June 2010 (UTC)

It's not easy or impossible - you can estimate the density by averaging the densities of the components eg for 40%v/v ethanol water the density would be estimated to be 0.40 x density ethanol + 0.60 x density water.

The actual figure may be different due to the way different shaped molecules fit together as well as short range bonding interactions that differ between different types of molecule, and other factors.

In fact the estimate will be pretty close for most mixtures. Only rarely do significant deviations occur.87.102.114.166 (talk) 20:04, 2 June 2010 (UTC)

Actually ethonol is miscible with water, so mixing 1 liter of 100% ethonol with 1 liter of 100% water will not give you 2 liters of liquid. Googlemeister (talk) 20:08, 2 June 2010 (UTC)

It's separate from miscibility...the question (and solutions (sorry:) ) offered apply for any ratio that does give a solution, even if the components are not soluble at other/all concentrations (miscible). DMacks (talk) 20:12, 2 June 2010 (UTC)

The gory math for "actual" (non-"ideal") liquids is in our volume of mixing article--the intro/definition gives a nice qualitative overview (and specific example for ethanol/water) and then quickly gets to illustrating just now "not easy" the real situation is. DMacks (talk) 20:09, 2 June 2010 (UTC)

The deviation from simple "sum of parts" is noticeable enough for ethanol/water that there are official tables for converting measured density of such mixtures into their component ratio--wouldn't need that if it were directly additive because could just solve the linear combination I guess? DMacks (talk) 20:20, 2 June 2010 (UTC)

(EC with all above) For this example you would take the average of 4 parts ethanol and 6 parts water (since that is what it is composed of. The density of water is 1 g/cm³ and ethanol is 0.789 g/cm³. It would come out to (1 g/cm³·6) + (0.789 g/cm³·4) = 9.156 ÷ 10 = 0.9156 g/cm³ --Chemicalinterest (talk) 20:12, 2 June 2010 (UTC)

87's formula is much easier. --Chemicalinterest (talk) 20:14, 2 June 2010 (UTC)

plumbers putty

i have black plumbers putty sealing my bathroom sink. my sink handle was creaking so i sprayed some pam on it. the next day the pam appeared to eat away the plumbers putty and turn it brown. how is this possible? --Alexsmith44 (talk) 19:53, 2 June 2010 (UTC)

What's 'pam' did you mean PAM (cooking oil) ? If so the oil in 'pam' will have diluted/dissolved the linseed oil in the Plumber's Mait

eg as an experiment add oil (any) to putty - you'll see that it gets thinner and more runny the more you add.

Is a 'sink handle' a Tap (valve) ? 87.102.114.166 (talk) 20:08, 2 June 2010 (UTC)

yes i mean PAM (cooking oil). even if the pam dilutes the linsead oil why does it turn brown? and how does it eat away at it if the outer layer is hard? —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 22:04, 2 June 2010 (UTC)

yes - putty goes hard over time - it may be evaporation, though it may also be polymerisation of the linseed oil - nevertheless hard things can be softened by things that dissolve them.

As for the brown colour - it was black before? Maybe the spray is diluting or washing away the pigment (v dark brown = black). It's difficult to say when I can't see it.

Have you got any spare putty - if so put a little in some oil and see what happens - it's possible that the colour in it will leach out (like dyes running from clothes in the wash). There still might be another explanation.

If you get stuck here you could as a last resort contact the manufacturer of the putty - they might even be interested that the colour is fading if its a flaw in their product.87.102.114.166 (talk) 22:10, 2 June 2010 (UTC)

BTW, once installed you shouldn't really be able to see the putty anymore. Its job is to sit between surfaces, not on top of them. The putty that is on top can be removed. Ariel. (talk) 00:28, 3 June 2010 (UTC)

i dont have any spare puddy i didnt install it. i used to use peanut oil to lubricate it and it didnt ruin the puddy. why did the pam they are both oils? —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 00:40, 3 June 2010 (UTC)

I don't know about the particular product you used, but a number of spray oils contain lecithin as a significant component. Unlike the triglycerides in "regular" oil, lecithin acts as a surfactant/emulsifier, and as such may act differently in solubilizing/leaching compounds. -- 174.24.200.38 (talk) 03:54, 3 June 2010 (UTC)

so what should i use to lubricate it  ? it needs to be a aerosol

Trigonal Bipyramidal Molecular Geometry

Hello. How was the trigonal bipyramid derived as the shape that allows bonding electrons stay as far from each other as possible? The bond angles in tetrahedral molecules equal. Why can't trigonal bipyramids? Thanks in advance. --Mayfare (talk) 21:35, 2 June 2010 (UTC)

Note that the square antiprism is also a minimum energy configuration even though a cube would give all the angles equal. You can't arrange 5 points evenly into a regular polyhedron Dmcq (talk) 21:48, 2 June 2010 (UTC)

how was it derived.. basically by adding an extra 'arm' to the tetrahedron, or arms to the flat triangular arrangement, and then fiddling to get the least variance in distane between arms.

or from knowledge of the various three dimensional polyhedrons (most simple ones were known early in human history) - and selecting from those that had five vertices.83.100.183.63 (talk) 22:42, 2 June 2010 (UTC)

What these guys are getting at is that the shape taken is the one that minimizes the energy associated with electrostatic repulsion. For some numbers of electron pairs, like 2,3,4, and 6, the minimum energy configuration is indeed one that gives equal bond angles. In the case of 5 and 7, there are no possible ways to arrange the electrons to give equal bond angles, and instead you get a trigonal bipyramid and Pentagonal bipyramid molecular geometry, respectively. If you don't believe that there are no ways to arrange 5 or 7 bonds around a central atom that gives equal bond angles, try it yourself. As to how it was discovered that these types of molecules like Phosphorus pentachloride take this geometry, I don't know. It could have been theoretically deduced to be the lowest energy configuration (and then actually measured somehow), or the geometry may have been deduced for individual molecules, and then generalized in VSEPR theory. There's not much history that I could find. As Dmcq points out, when you get to the case of 8 bonds around an atom (very rare), there is a way for those bonds to have constant bond angles; the bonds could lie at the corner of a cube. However, that's not the least energy configuration. So it's not true, in general, that a configuration that gives constant bond angles is necessarily the configuration that a molecule actually attains. Buddy431 (talk) 22:55, 2 June 2010 (UTC)

What are we seeing when we look at the sun?

Well we all know that the sun is mostly hydrogen. But hydrogen is invisible, and when hydrogen burns, it burns invisible too I believe. So what exactly are we looking at when we look at the sun? ScienceApe (talk) 22:24, 2 June 2010 (UTC)

You're looking at the light emitted from the sun.83.100.183.63 (talk) 22:30, 2 June 2010 (UTC)

(ec) Conventional wisdom says that it emits light because it is hot - white hot in fact (in the same way a Incandescent light bulb emits light because it is hot).83.100.183.63 (talk) 22:37, 2 June 2010 (UTC)

Thermal Radiation, essentially. Anything with a temperature above absolute zero "glows". That is, it releases electromagnetic radiation at a variety of wavelengths dependent on how hot it is. Humans glow mostly in the Infrared range. The sun glows across a wide range of wavelengths, including Visible light. Buddy431 (talk) 22:36, 2 June 2010 (UTC)

I was going to suggest Blackbody radiation but that just redirects to the already linked thermal radiation article.. Vespine (talk) 23:03, 2 June 2010 (UTC)

Hydrogen burns in oxygen with a colorless flame - but what's happening in the sun is nothing to do with 'burning' - that's a confusing term! The hydrogen is participating in fusion reaction where two atoms of hydrogen are crushed together to make a helium atom and producing a heck of a lot of heat and light in the process. The color of sunlight corresponds to Black body radiation at 5800 degC - which is the surface temperature of the sun. You'll need to read the black body article to understand the precise reason for that. The color (if you were out in space) would be almost perfectly white - it only looks yellowish here on earth because so much of the blue light is scattered out there into the sky (white minus blue equals yellow!). SteveBaker (talk) 23:13, 2 June 2010 (UTC)

Strictly speaking, 4 hydrogen atoms create one helium atom, in the Proton-proton chain reaction (mostly) in the sun. Buddy431 (talk) 23:30, 2 June 2010 (UTC)

Neatpicks!!

• The use of the word burn to describe the nuclear reaction that happens in the sun is pretty well stablished language.
• To say that the sun "is almost perfectly white" is a pretty subjective thing to say. It looks pretty white to me even after its light's been filtered by the atmosphere.

Dauto (talk) 01:58, 3 June 2010 (UTC)

I'm still a little confused about the "color of the Sun" thing. I tend to think the main reason we think of the Sun as yellow is that that's the color when it's low on the horizon, but not quite low enough that we'd call it sunset (when it's orange-red). When it's higher in the sky, it's painful to look at and we usually don't.

But when you see the disk of the Sun through a thin layer of cloud, it appears pure white. So the question is, does the cloud layer change the perception of color, or does it just reduce the intensity enough to look at?

On the other hand, I do have the sense that sunlight on objects appears yellowish. But I can't quite figure out what that even means. --Trovatore (talk) 07:25, 3 June 2010 (UTC)

Trovatore, our perception of color is as much a consequence of our eyes and brains phisiology as it is a consequence of the spectrum of the light itself. The eyes and brain do extensive processing that allow us to have a fairly consistent color perception regardless of the king of light used to shine on the object. Because of that the question of whether the sun is white or yellowish is more or less a meaningless question. From a purely spectroscopic point of view the sun is actually greenish, but we don't see that. To answer your question, light that goes through a thick atmospheric layer becomes yellowish -> orangish -> redish while light that goes through a cloud layer doesn't, simply becoming dimmer. Dauto (talk) 15:13, 3 June 2010 (UTC)

• Sure it's established language, but the original poster spoke of how hydrogen "burns invisible I believe", and that's about combustion with oxygen, not fusion. When the question shows signs of confusing two concepts, it's necessary to distinguish them. --Anonymous, 04:36 UTC, June 3, 2010.

Of course we should clarify any confusion or misconception that the OP might have, but we should nopt tell them not to use the word 'burn' when that's exactly the word used by the specialists in the field. Dauto (talk) 15:00, 3 June 2010 (UTC)

We're seeing photons that were created eight minutes ago. When hydrogen atoms fuse into helium, that resulting helium has slightly less mass than the hydrogen did. From E=MC-squared, you can see that the tiny loss of mass (M) turns into a relatively huge amount of energy. That energy is released as photons, an infinitesimal percentage of which reach our eyes (I may have the following wrong: I believe one-third of the photons are "visible," and the other two-thirds are invisible gamma rays). Incidentally, the CNO cycle may be a second type of solar fusion, and it also releases photons. 63.17.89.8 (talk) 02:13, 3 June 2010 (UTC).

The CNO cycle is a different set of reactions that has the same net effect as the p-p reactions - That is the conversion of hydrogen into helium. Dauto (talk) 02:46, 3 June 2010 (UTC)

The photons created by nuclear fusion in the Sun are reabsorbed. The light we see comes from the surface of the Sun and is blackbody radiation, as already mentioned. Possibly you're thinking of neutrinos, ~2/3 of which are invisible to certain detectors in a formerly mysterious way (the solar neutrino problem). -- BenRG (talk) 09:28, 3 June 2010 (UTC)

What about this though? What am I looking at in this picture? Looks like a surface of lava (I know it's not, just saying it looks like that. What is all that red and orange stuff I'm seeing? ScienceApe (talk) 00:41, 4 June 2010 (UTC)

Is it really eight minutes ago though? From Sun: "The gamma rays (high-energy photons) released in fusion reactions are absorbed in only a few millimeters of solar plasma and then re-emitted again in random direction (and at slightly lower energy)—so it takes a long time for radiation to reach the Sun's surface. Estimates of the "photon travel time" range between 10,000 and 170,000 years.[42]" How many of the photons reaching the earth travelled from the core to the photosphere and then to Earth and how many are the result of black body radiation? --Rajah (talk) 22:23, 7 June 2010 (UTC)

Same exact deal...black body radiation. Lava is at between 700 and 1200 degrees C (1000 to 1500K), and if you check the black body diagram on the left here, you'll see that that's in the red/orange range. The sun, at around 6000K is in the white region. The color at which most hot objects glow is directly related to their temperature. SteveBaker (talk) 01:32, 4 June 2010 (UTC)

That's not lava... it's a solar flare! The red and orange stuff is probably thermal radiation from hot plasma (that is, emitting visible light just like the rest of the sun does). Note that solar flares are much hotter than the surface of the sun, so can spit out a lot of radiation for their size. Also realize that electromagnetic radiation can be generated in other ways besides thermal radiation; when you accelerate matter (especially charged particles) to relativistic speeds (as occurs in solar flares), photons can be emitted then too (I don't really understand the mechanism there). This is what's believed to cause Gamma-ray bursts, for example. Buddy431 (talk) 01:45, 4 June 2010 (UTC)

But when I look at that photo, I'm not just seeing photons, I'm seeing matter aren't I? I think it's plasma if I'm not mistaken, so would it be hydrogen plasma? So I guess my question is, is hydrogen visible to the naked eye when it becomes a plasma? ScienceApe (talk) 04:11, 4 June 2010 (UTC)

Yes it is the pink colours are relatively mild plasmas generated electrically in general all plasmas Plasma (physics) emit light because of the high energy they are in.83.100.183.63 (talk) 13:50, 4 June 2010 (UTC)

Sure, you're seeing photons. That's what light is. The hot hydrogen plasma (or the lava, or even your pet cat) radiates photons over a range of frequencies (colors) with a peak frequency that depends on the temperature. At the temperature of your cat, those are in the infra-red range, in the case of the lava, it's in the red/orange range - and in the case of the sun, it's pretty much white. Those photons travel outwards in all directions and some of them arrive inside your eyeball where they are absorbed by chemicals in the rod and cone cells in your eye. Hence the perception of "color".

But that's not the whole picture - your cat doesn't look black (well, unless it's a black cat!). That's because objects also reflect light - so all of those photons coming from the sun hit your cat, some of them are absorbed and the rest reflected...and again, some of the reflected ones hit your eye. So the color of the light arriving at your eye when you look at things is a combination of the light they emit and the light they reflect (and for translucent objects, the light that passes through them).

In the case of really hot things like lava and the sun's surface, almost all of the light is emitted - so the color you see depends on the emitted light spectrum - which (for most things) follows that black body radiation curve. For much cooler objects, that radiation is largely in the infrared and you can't see it because your eyes aren't sensitive in that part of the spectrum - so the only light you see coming from your cat is the reflected light. There is also reflected light coming from the sun - but there is so very little starlight reflected from the sun that all you really see is the emitted light.

If you take a chunk of iron and gradually heat it up, it starts off at room temperature, looking slivery/grey because it's reflecting light and emitting in the far infrared where you can't see it...but as it heats up, it passes the Draper point (about 525 degC) - that emitted light starts to climb in frequency and edge into the red end of the visible spectrum. What we see is that the metal starts to glow red - it's still reflecting light but the relatively tiny amount that it reflects is now dwarfed by the amount it's emitting. As the metal gets hotter, it glows orange (now it's about 1000 degrees - as hot as lava - and roughly the same color), then yellow, then eventually white. "White hot" means "about as hot as the surface of the sun" - and you have to get your metal up to about 5000 degrees to do that. SteveBaker (talk) 14:11, 4 June 2010 (UTC)

Contents of Organic Pesticide

I just used an organic pesticide that contains the potassium salt of various fatty acids as its main ingredient. Will this actually kill/repel/do something to insect pests or did I just waste my money on some oily, salty water?24.88.87.41 (talk) 22:41, 2 June 2010 (UTC)

Maybe somebody else can give you a better answer, but the way to test for it is to spray some plants with this, and leave others of the same type alone. See how they stack up. Falconus^{p t c} 22:49, 2 June 2010 (UTC)

There's an explanation of how they are supposed to work here [8] It looks like they affect the cell wall of things - also works on plants [9] There's plenty of hits on http://www.google.co.uk/search?q=fatty+acid+pesticide&hl=en&start=10&sa=N - so I'd think there must be something in it ??

For aphid on apple trees I think a common treatment is to spray soap on the trees - probably does work, or at least people think so [10] /83.100.183.63 (talk) 22:50, 2 June 2010 (UTC)

This could be just what I've "heard" but i always thought there was nothing wrong with organic pesticide, efficacy wise, you just need to spray more of it and more often for it to be as effective as the non organic counterpart. That's probably just what the planet rapists want us to believe. Vespine (talk) 23:01, 2 June 2010 (UTC)

Sure if you spray enough of many things you'd kill the pest. One of the ways would be by killing the plant or failing that any organisms thats eat even a tiny bit of it. Nil Einne (talk) 00:53, 3 June 2010 (UTC)

Trouble is with "nothing wrong efficacity-wise if you just spray more" is that that costs money. Fine, if like me you're growing a couple of dozen Broad bean plants in your back garden. So over the growing season you have to buy a couple or three bottles of fatty acid pesticide at £1.49 instead of one bottle of something non-organic (if as an amateur you could get it) at £1.00. No big deal. However if you have 100 acres of beans, and you're trying to make a living out of them rather than playing at farming (like me) the financial picture's rather different. Tonywalton ^Talk 01:05, 3 June 2010 (UTC)

There's a good amount about them on Google - just search for /fatty acid pesticide/ and similar terms. Here's one example of many. Yes, they do work OR: I have an unholy glee in spraying a fatty acid pesticide on my roses and watching the greenfly die, although you may need to use more, or apply more often, than, say an organophosphate or pyrethrin. You don't say what you're trying to kill on what crop, but personally I'd much rather get rid of aphids on my broad beans with something rather less poisonous to humans than some insecticides. Of course you could always try Enviromesh instead, if you want to avoid being called a "planet rapist". The mesh stuff also keeps pigeons off, which is a definite plus! Tonywalton ^Talk 00:52, 3 June 2010 (UTC)

We have an article on Insecticidal soap: "Insecticidal soaps are used against soft bodied insects and mites ... Insecticidal soaps have been about 40-50% effective against these pests." -- 174.24.200.38 (talk) 03:49, 3 June 2010 (UTC)

I probably should have qualified the sarcasm of my planet rapist comment, i don't really believe that, i think "organic" farming is far more of a scam then conventional farming. Vespine (talk) 03:51, 3 June 2010 (UTC)

Yes I thought you were being sarcastic but wasn't sure Nil Einne (talk) 05:59, 3 June 2010 (UTC)