Wikipedia:Reference desk/Archives/Science/2010 April 18

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April 18

Vegetarianism and Diabetes

Is there any medical reason a diabetic should not be a vegetarian? A nutritionist told an acquaintance of mine that it's basically impossible for a diabetic to be healthy and satisfied on a vegetarian diet, but I've also heard of a vegetarian diet being recommended to control diabetes. (Please note, I am NOT asking for medical advice here. I'm not diabetic, and I'm a vegetarian for ethical reasons and wouldn't return to eating animal flesh even if I thought my health would benefit by it in some way. This is more of a "settling a bet" kind of question, even though I haven't actually made a bet.) 71.104.119.240 (talk) 02:02, 18 April 2010 (UTC)

Diabetics basically can not properly handle carbohydrates. So it's better for them to get most of their calories from protein instead. This is very very hard to do on a vegetarian (even more so a vegan) diet. The current recommendation is not to cut out carbs totally, but rather to limit them. But anecdotally diabetics who cut carbs almost totally out of their diet do very well. Ariel. (talk) 02:10, 18 April 2010 (UTC)

What Ariel said was unsubstantiated, dangerous and possibly deadly bullshit. Diabetic diets include prescribed amounts of carbohydrate for every meal. Please check with such reliable sources as the American Diabetes Association rather than random persons posting nonsense on the internet. See [1] for instance. Edison (talk) 03:21, 18 April 2010 (UTC)

I said that: "The current recommendation is not to cut out carbs totally, but rather to limit them.". But deadly? Seriously? And despite what the American Diabetes Association says, not everyone agrees, and here is a study that says so. This is not a settled issue though. Ariel. (talk) 04:09, 18 April 2010 (UTC)

discussion about the ethics of vegetarianism

I wasn't aware that there are ethical reasons to be a vegetarian. Dauto (talk) 02:51, 18 April 2010 (UTC) Dauto, Thats a moveable feast. See Vegetarianism and religion. AFAIK ref the OP there is no problem at all with Diabetes and being vegetarian. --BozMo talk 07:34, 18 April 2010 (UTC) I don't know what you mean by moveable feast. Sure, some religions promote vegeterianism, while some other relegions specifically call for non-vegeterian dishes for specific porposes. Fish and lamb come to mind. Some of them forbid specific kinds of meat such as pork or beef without calling for outright vegeterianism. The overall picture is that relegions are all over the place. My question wasn't about relegion though, it was about ethics which is a different thing. Dauto (talk) 14:08, 18 April 2010 (UTC) There is a big difference between religion and ethics (they are related concepts, certainly, but not equivalent). --Tango (talk) 14:45, 18 April 2010 (UTC) Most vegetarians are vegetarian for ethical reasons. They don't think it is ethical to kill animals for food or they don't think it is ethical to treat animals in the way some animals bred for food are treated so don't eat any meat in order to not support the industry or they practise a religion that says it is unethical to eat meat. --Tango (talk) 14:45, 18 April 2010 (UTC) Does that mean that most vegetarians see the meat eaters as a bunch of ethicless people? I rather doubt that. Dauto (talk) 15:56, 18 April 2010 (UTC) Just because it hasn't appeared yet: Ethics of eating meat. Dauto, it would be unfair to call someone who has a different set of ethical principles to oneself "ethicless". 129.234.53.144 (talk) 17:33, 18 April 2010 (UTC) In general it's probably not "ethicless" so much as "ethically challenged". Most vegetarians-for-ethical-reasons in the western world, even militant ones, recognize that there is a large culture and history of meat-eating, so they are likely to believe meat-eaters to be morally ignorant, rather than morally depraved. Most ethics-based pro-vegetarianism campaigns focus on "conscience building" and promoting awareness, rather than moral condemnation. ("You can be a better person" rather than "You are an horrible, evil person.") All this is highly dependent on the vegetarian, though. I've met quite a few who for whom it is a completely personal choice, and who really don't care what others do. -- 174.24.208.192 (talk) 17:48, 18 April 2010 (UTC) Have to agree with 71.104 below, I'm not saying people have to agree with the ethical reasons and I perhaps shouldn't be surprised about a debate about the ethical reasons on the RD even if it's OT, but I'm rather surprised people are seriously unaware plenty of people have ethical reasons (even many of the religious ones have reasons based in ethics even if many religious don't agree with such reasoning) Nil Einne (talk) 10:40, 19 April 2010 (UTC)

25 years ago my first husband became Type 1 Diabetic. He had to inject insulin as well as alter his diet. Being the cook in the family, I well remember this diet! Only 2 portions of red meat a week: change to wholemeal/whole grain products for everything refined (bread, rice, pasta). Plenty of veg. Potatoes with skin on only. No added sugar: very little fat. Been trying to find a reference for this diet, but as it was so long ago I think it's not available. Current NHS advice is that there is no special diet but just to eat healthily: however, the GI or GL diets are well received among the diabetic community. [2] So, is being vegetarian compatible with managing diabetes? It looks like it - providing you still remember to eat healthily! Eating cheese and chips every day is never a good idea (unfortunately). --TammyMoet (talk) 08:13, 18 April 2010 (UTC)

This study (by a vegetarian advocacy group) claims to show vegetarian diets can be quite useful for diabetics. The people in this study were eating a very carefully planned diet though, no chips and cheese I'm sure. Qrsdogg (talk) 13:14, 18 April 2010 (UTC)

Much thanks to those of you who took the time to consider and compose thoughtful responses to the question I asked. As for those of you who felt the need to take the discussion off-topic with what I suspect on the basis of personal experience has more to do with criticism of my moral choices than any actual curiosity about the ethics of vegetarianism (including one individual who felt the need to send a message to me personally) - I only mentioned my ethical stance in order to clarify that I was in no way asking for medical advice by posing this question, as I had no intention of changing my habits no matter what the answer was. Whatever my own private opinions may be, there was nothing judgmental or proselytising about the question I posed; I didn't come here to engage in debate, and I have no interest in doing so. If you must know, though I seriously doubt there's anyone hanging around the Wikipedia reference desk who isn't familiar with the concept that some people don't eat animal flesh for reasons of conscience, Tango and 174.24.208.192 had it about right. 71.104.119.240 (talk) 10:32, 19 April 2010 (UTC)

Sunrise and sunset

In the southern hemisphere (l live in Australia) the day of earliest sunrise is about two weeks before the summer solstice, and the day of latest sunset is about two weeks after the summer solstice. The day of latest sunrise is about eight days after the winter solstice, and the day of earliest sunset is about eight days before the winter solstice. Is it the same in the northern hemisphere, or the opposite? If there is a difference, why? Dolphin (t) 06:04, 18 April 2010 (UTC)

The solar time article, specifically the section on apparent solar time gets at the reasons for this. Around the summer solstice in the Southern hemisphere, each apparent solar day is longer than average, both because because of the tilt of the Earth's axis and because the Earth is near perihelion, which pushes the sunrises and sunsets forward each day. In the winter the apparent solar days are also longer than average because of the tilt of the axis, but tempered by the fact that the Earth is near aphelion so the effect is smaller. In the northern hemisphere the equivalent effect would be that the earliest sunrise would probably be about 8 days before the solstice and and the latest about 2 weeks after the winter solstice (I don't know for sure that the numbers are exactly the same, but I assume so). See also equation of time. Rckrone (talk) 07:29, 18 April 2010 (UTC)

You can ansewer the first part of this yourself here. The World Clock – Time Zones--Aspro (talk) 07:38, 18 April 2010 (UTC)

To add something to what I said before, the degree of this effect is going to depend on your latitude. At latitudes closer to the equator where the length of daylight fluctuates less, the shift in the apparent solar day compared to the official time will dominate more in terms of determining earliest/latest sunrise/sunset, while at farther latitudes the larger fluctuation in length of daylight will put those earliest/latest days closer to the solstices. So those 8 days and 2 weeks numbers would apply only to the northern latitude equivalent to yours. Rckrone (talk) 07:56, 18 April 2010 (UTC)

Yes, it is the same in the northern hemisphere (our earliest sunset is mid-December and our latest sunrise is early January). I puzzled over this apparent asymmetry for about forty years (not continuously!), until I realised that the effect is caused simply by the shift in the time at which the sun is at its highest (local noon), so it is not an asymmetry at all (at least not in the way I had thouhgt). The BBC gives a concise explanation. The effect changes over centuries, but has been this way round since the year 1246. Dbfirs 08:19, 18 April 2010 (UTC)

OP, if you are correct that "earliest sunset is about eight days before the winter solstice," then NO it is not the same throughout the north. Where I live, the earliest sunset occurs on December 5th-ish. By the way, if we used sundials rather than clocks, earliest sunrise/latest sunset would occur on or about the date of the summer solstice, and vice-versa for the winter date. But we use clocks based on the artificial "mean sun," which always goes exactly the same speed; this leads to the discrepency between clock-noon/midnight and true-noon/midnight, which in turn makes the earliest/latest (clock-time) "horizon crosses" dates vary from the solstice dates. 63.17.77.124 (talk) 02:29, 20 April 2010 (UTC)

My thanks to everyone who contributed to this thread. All contributions have been very useful. I am now much wiser on the matter than I was a week ago. I will summarise the situation as follows:

• Regardless of the hemisphere, the earliest events (earliest sunrise and earliest sunset) occur earlier than the solstice. (Earliest sunrise occurs earlier than the summer solstice; and earliest sunset occurs earlier than the winter solstice.)
• Regardless of the hemisphere, the latest events occur later than the solstice. (Latest sunrise occurs later than the winter solstice; and latest sunset occurs later than the summer solstice.) Dolphin (t) 02:57, 20 April 2010 (UTC)

A neat summary! If I understand the Equation of time correctly, this pattern is just coincidental because the graph crosses the axis around the time of the solstices (zeros on Christmas day and June 13th), and the effect at the December solstice should be greater than the effect at the June solstice (does this correspond to observations in both hemispheres?). This will change in a few centuries. Dbfirs 12:45, 22 April 2010 (UTC)

Concentration of urine

In which part of nephron actual concentration of urine is determined? —Preceding unsigned comment added by Aditya Handargule (talk • contribs) 07:34, 18 April 2010 (UTC)

I don't understand the question, please clarify. StuRat (talk) 13:59, 18 April 2010 (UTC)

Perhaps the questioner can find answers in the articles Nephron, Kidney (Kidney#Osmolality regulation, perhaps?) or Renal physiology -- 174.24.208.192 (talk) 17:26, 18 April 2010 (UTC)

Short answer: collecting ducts alteripse (talk) 18:57, 18 April 2010 (UTC)

enzyme activity

an increase in enzyme activity in a cell is mechanistically due to trascription. this mechanism can be domenstrated by: a)measuring total enzyme acticity in the cell free extract. b)ELISA. c)nothern blot d)western blot. —Preceding unsigned comment added by Pradyumn chauhan (talk • contribs) 10:00, 18 April 2010 (UTC)

We won't do your homework for you. The real point of multiple choice homework questions like this is not to "get the answer", but to make you look up, read about, and understand the concepts involved in the question. I suggest you start with transcription (genetics) and also check out some or all of mRNA, enzyme, ELISA, northern blotting and western blotting. If you have problems understanding any of these pages come back here and we will be glad to help. 131.111.185.69 (talk) 10:58, 18 April 2010 (UTC)

Proposed emergency ash reducing: "Rapid glacier removal operation" off the top of volcano on Iceland.

Goal: Substantially cut down on the international healthcare expenses, in the years to come, stemming from the currently ongoing eruption.

Perhaps a little over-dramatized (but not too much!), one might say that:

The Volcanic ash in the air, is basically microscopically tiny pieces of razor sharp broken glass that is swirling around, all over Europe.

(Hence, neither you nor the Wildlife of the northern hemisphere (which cannot stay indoors keeping the doors shut on bad days), would like to have too much, or any at all, of this in your lungs!).

The ammount of emitted volcanic ash is first and foremost determined by the Volcanic Explosivity Index (VEI) of the volcano in question. (The VEI ranges from "gentle" (VEI=0) to "mega-colossal" (VEI=8)).

The ongoing eruption of the volcano: "Eyjafjallajökull" on Iceland, is currently rated as having a VEI between 0 and 1. (i.e. the ammount of volcanic ash should not be too bad).
But the ash-problem is dramatically exasperated by the meltwater from the Glacier that rests on top of the volcano, because the meltwater flows down into the volcano where it then explosively evaporates. ;-(

Q1: Therefore I wonder, why are not the combined military forces of Iceland, Europe, Russia and North America, trying to mitigate the ash-problem by employing Directed-energy weapons and microwave Masers (so that the glacier could be melted away as if it was ice inside a Microwave oven).
(Some of the pictures in the news seems to show that because of wind in the area, then visibility is good enough! i.e. the target glacier is not covered by smoke that would block enery rays).

Q2: If the above, for some reason, is out of the question then why are they not employing Napalm to do the job?
Even though one, of course, would loose the "surgical precision" of cutting away the ice with the above mentioned "rayguns". Yet, there surely must be more than one heroic and competent icelander that would be willing to walk up there and skillfully place the Napalm by hand! (Of course one would have to be really confident that the result of ones action would be an overall reduction of the waterflow down into the volcano!).

Of course, within a couple of weeks then the volcano itself will have melted a hole in the glacier, but much of that meltwater will have gone down and exploded in the volcano. A few weeks or days of unnecessary intense ash exhaustion ammounts to a big difference!

One might argue that the above mentioned operations would be horribly expensive -- and they would have to act really fast, which will make it even more expensive -- but compared to the saved worldwide expences for healthcare in the years to come, then the cost of a "Rapid glacier removal operation" would be truly negligeble.
--89.9.57.218 (talk) 14:28, 18 April 2010 (UTC)

This may cause bigger problems:

Hooper warned that the eruption may be only a taste of the future if climate change causes ice sheets to melt further. As the last ice age ended, volcanic activity in Iceland increased 30-fold because of reduced pressure on the earth’s mantle.

“Since the 19th century the ice caps in Iceland have been shrinking yet further,” said Hooper. “This will lead to additional magma generation, so we should expect more frequent voluminous eruptions in the future.” Count Iblis (talk) 14:34, 18 April 2010 (UTC) |}

One off-question reply (above) collapsed!
Please remember the How to answer a question guideline at the top of this page! which says: "Keep your answer within the scope of the question as stated.". (The reference desk is not a chat-room). (Well, not quite anyway!).
--89.9.5.27 (talk) 15:04, 18 April 2010 (UTC)

The ash is very high in the atmosphere (that is why it can move so far), we are at the bottom of the atmosphere. While it will eventually fall to earth (and is already doing so in places), the medical concerns are fairly minimal (the only medical advice I saw when ash was falling in Scotland was for asthma sufferers to make sure they had their inhalers with them when going outside, they weren't even advising them to stay indoors). I haven't seen any estimates of the medical cost, but I expect them to be small. The economic cost of suspending all air travel will probably be greater, anyway. Melting the glaciers could cause additional problems that would be worse (increased sea levels, increased eruptions, decreased albedo resulting in greater global warming, etc.). --Tango (talk) 14:51, 18 April 2010 (UTC)

(ec) I think the proposal falls under the category of Geoengineering - using large-scale, technological actions to control earth processes. Two problems emerge: first, it is not clear that any action we can take (including your ice-melting suggestion) would actually mitigate or even impact the danger due to volcanic eruption or ash. Our understanding of the complex interplays between these geophysical phenomena is limited, to say the least. We might even make the situation worse. The second problem is that such actions are very expensive, and it is hard to justify very expensive programs, especially if the results will be uncertain. One issue is that the scale is huge - we would need to expend considerable resources to match the quantity of energy that a volcano can unleash - and those resources might be better used to mitigate the problem in other ways. Nimur (talk) 14:57, 18 April 2010 (UTC)

Hmm...

1. There is no doubt about the fact that water flowing into a volcano will cause dramatic explosions! And thus cause substantially increased ammounts of volcanic ash!
2. The melting of just one small glacier will not be more than a «drop in the ocean» and will have far smaller consequences than all the ash avoided

--89.9.5.27 (talk) 15:16, 18 April 2010 (UTC)

Do you have any idea of the scale of things here? The energy to do what you suggest is enormous. We don't have a directed energy weapon that could melt even a minuscule amount of that ice. And napalm would not do a thing - all the heat goes up, almost none would melt the ice. You would probably need a volcano to melt that much ice :) Ariel. (talk) 15:27, 18 April 2010 (UTC)

That crazy idea doesn't have an icecube in hell chance of working. Dauto (talk) 15:29, 18 April 2010 (UTC)

I ran some numbers, assuming about 300x500x500 meters of ice, you would need 1.501x10^16 joules of energy. Look at Orders_of_magnitude_(energy)#1015 to see how much energy that is - it's about 10 megatons of TNT, i.e. an atom bomb - actually several of them. And even that would not be enough, since most of the energy would be wasted, and sent up into space. Ariel. (talk) 15:38, 18 April 2010 (UTC)

Ah, yes! These are the kind of enlightening replies that I (the OP) was hoping for. Thank you all!
Hmm.. If napalm will not work because most of its heat energy would go upwards...
...Then how about Thermite?
Of course one might need a "few hundred pounds" of it, but one might be able to use it to burn a channel in the glacier, which would divert at least large ammounts of water away from flowing into the volcano. --89.9.5.27 (talk) 15:45, 18 April 2010 (UTC)

A few hundred? While thermite would probably do a good job, and iceland actually produces lots of aluminium, a quick calculation shows that termite can melt about 11 times it's mass in water ice. So 300 pounds of thermite can melt about 36 gallons of water. I don't think that's going to help much. The scale of planetary events is stupendous. Humans don't come close to controlling those quantities of energy. Ariel. (talk)

I have no doubt that if we had solid evidence that melting a glacier would be worth the effort, we could marshal the technology and the resources to do what the OP has suggested (perhaps the most effective technologies would not be napalm or ray-guns, but we could analyze and design an effective method). I disagree with some of the assertions that humans are incapable of controlling that much energy. For perspective, look at what humans are already are capable of. We regularly move mountains; we make the rain start or stop; we control the weather; we generate earthquakes (and control for the natural ones); we split continents in half (actually, we've done this more than once!); we have moved the ocean; we have changed the topology of canyons and filled them up; we have chemically modified our atmosphere many times in many ways; and we harness more energy than a volcano every single day. But all of these things are difficult; they are expensive, they require a huge degree of cooperation, and many times, they have unintended consequences - sometimes the side-effects outlive the original purpose with catastrophic results. The above seemingly-miraculous feats of technology have historically been justifiable, despite the resources necessary. So - while the nay-sayers here are bringing up some valid numbers - and it is totally accurate to say that it would require a huge quantity of prohibitively expensive resources - it all boils down to this. If we decided, with a confidence level beyond a reasonable doubt, that we could make this volcano situation better by melting ice (or any other sort of action), we would take that action, despite its resource-cost. But as of right now, our understanding of the situation is that its effects are actually too small to warrant the sort of massive engineering and economic burden of addressing the situation at the source. It is more efficient to divert aircraft pathways - it is more efficient to accept and plan for (or neglect) any potential global health or climate hazards. All things considered, and even though this volcanic eruption is huge in scale, it is a metaphorical "drop in the bucket" in terms of global resource allocation. It is more effective for us to focus on small expenditures of energy - like dredging the East River to allow super-post-Panamax ships to dock on the East Coast, saving millions of gallons of petroleum that would otherwise be needed to drive freight from a more distant port. So, a tiny project like dredging a river can have trillions of dollars of economic significance; while "de-volcano-izing Iceland" would be extremely expensive with very little direct return (a mere $200 million per day, petty change by comparison). Ultimately, teams of politicians make decisions about which resource expenditures are "cost-effective" - hopefully guided by scientific and engineering analysis. But I think it's unfair to the OP to categorically tell him/her that his idea is "impossible." It's certainly possible - it's just not efficient. Nimur (talk) 16:51, 18 April 2010 (UTC)

A bit of lateral thinking to reduce the resources required: On the equator each square meter receives about 400 watts of the sun's energy per square meter. At the latitudes of Iceland, it might be possible to speed up the melting by reducing this glacier's albedo. This could be done with such things as tons and tons of lamp black or even tons and tones of grey dust. The only problem remaining is where to get enough at such sort notice and how would you cover twenty square miles of glacier with it... Oh! But wait !!!--Aspro (talk) 16:58, 18 April 2010 (UTC)

Perhaps most interesting is that in this era of presumed energy shortage, it is still not cost-effective to harness the immense quantity of freely available geothermal energy that is currently being wasted "melting ice" instead of powering our automobiles and internet data centers. Iceland is ahead of the game, but imagine if they developed the technology to capture and export the volcanic energy, instead of letting it go to waste. I don't know what a volcano-energy-harvester would look like, but I have a sneaking suspicion it would look a lot like this: thousands of tons of very expensive steel structure, tubes, pipes, pumps, and chemical reactors. But why would we waste our efforts harnessing easily-available energy that rose to the surface under its own power, when there is so much energy available many miles below the ocean floor, thousands of miles away from where it is needed? Nimur (talk) 17:04, 18 April 2010 (UTC)

The big problem with harvesting energy from a volcano is that it is too concentrated: you'll have trouble keeping the harvesting equipment intact. --Carnildo (talk) 01:41, 20 April 2010 (UTC)

If shrinking of glaciers increases volcanic activity, then that should be proof that global warming increases volcanic and seismic activity! But the problem with your idea is that the current eruption could also trigger a second eruption at Katla which sits underneath a larger glacier and would produce even more ash. ~AH1^(TCU) 01:03, 22 April 2010 (UTC)

Asexual reproduction

What is the real difference between fragmentation and budding? Is strobilation a form of budding? Or should it be considered a form of larval amplification? Propagule formation is or is not a type of asexual reproduction?

Thanks in advance.--82.55.196.145 (talk) 15:56, 18 April 2010 (UTC)

I think fragmentation happens to the organism, while budding is done by the organism. To me strobilation does not seem to be a form of budding, because the bud is specially made for the purpose, but strobilation is pieces of the entire animal. But all that is just guessing. Ariel. (talk) 17:08, 18 April 2010 (UTC)

... and propagule can be either sexual or asexual, depending on the part used. Dbfirs 20:14, 18 April 2010 (UTC)

Ok, thanks; I imagined the difference was the one suggested by Ariel, but I read that bulbils of Allium are produced through a fragmentation event! Ephyrae are made for the specific porpouse of strobilation and they are not pieces of the animal, but real individuals. I'm a little bit confused.--87.3.123.226 (talk) 11:04, 19 April 2010 (UTC)

iodized salt

how do they add the iodine to salt . do they mix it with powdered iodine or soak it in a liquid iodine solution —Preceding unsigned comment added by Jonny12350 (talk • contribs) 16:05, 18 April 2010 (UTC)

The NY times reference link in our iodised salt article says they spray two ounces of potassium iodate on each ton of salt ... in the Third World. Haven't found yet the process used in the industrialized countries. Comet Tuttle (talk) 16:17, 18 April 2010 (UTC)

Here it is: This page from the "Salt Institute" says, "Modern salt plants routinely spray potassium iodide or potassium iodate onto the salt while it moves along a conveyor belt before it is packaged. In lower-tech operations, iodine is sometimes added as a dry ingredient and physically mixed with the salt." Apparently the US FDA doesn't permit the use of potassium iodate for this purpose, though it's the most common additive globally; so in the US they have to add a couple of additives because otherwise, "Without a stabilizer, potassium iodide is oxidized to iodine and lost by volatilization from the product." Comet Tuttle (talk) 16:30, 18 April 2010 (UTC)

The bit about potassium iodate made me wonder why it's not permitted by the FDA, and this page has some more info if anyone else is curious. That page also has some complaints on the accuracy of the wikipedia article on potassium iodate. Ariel. (talk) 16:52, 18 April 2010 (UTC)

Another discussion of various methods. --jpgordon^{::==( o )} 17:55, 18 April 2010 (UTC)

Wikipedia is the encyclopedia anyone can edit...why didn't they fix what was wrong (or even add a question to the talkpage, so it would get fixed) instead of just complaining off-site? They have two complaints: a cite-needed statement about FDA approval (now removed, because they link an FDA letter to the contrary) and a dosage chart...from WHO which they claim is a bogus-pills vendor? Anyway, back to your regularly-scheduled discussion. DMacks (talk) 03:44, 19 April 2010 (UTC)

Saltwater ecosystems

I am trying to find information on saltwater ecosystems, mainly what animals live in saltwater and what their diets are. Can someone help me out? Thanks, Eagles 24/7 (C) 17:28, 18 April 2010 (UTC)

It helps to know that the ocean is the most common natural salt-water environment - so you can search for life forms that live in the ocean. Invariably, these will be saltwater ecosystems (though some organisms live in both salt- and fresh-water, or brackish environments). Take a look at the "lifeforms" section of our marine biology article to get started; there are hundreds of links within that section alone. There are too many animals in such environments to make a general statement about their diet - each organism fulfills a different ecological niche - but if you can narrow down a little, we can help you find information about specific organisms. For example, baleen whales are marine animals that mostly eat krill. Nimur (talk) 17:51, 18 April 2010 (UTC)

Which, of the millions of species which live in saltwater, are you interested in ? StuRat (talk) 17:52, 18 April 2010 (UTC)

@Nimur: Thanks, I'll go check that out. @StuRat: I'm not really sure which ones I'm looking for, but I'll figure it out. Thanks, Eagles 24/7 (C) 18:02, 18 April 2010 (UTC)

Historical Alternatives to Ballistic Pendulums

Hello. Were there any historical alternatives to ballistic pendulums when finding bullet speed (perhaps shooting a bullet in a tank of water, which would be safer)? Thanks in advance. --Mayfare (talk) 17:29, 18 April 2010 (UTC)

SPARK SHADOWGRAPHS have been in use for a while.[3]. There are also ballistic boxes but I don't know how good they are for working out velocity.[4]--Aspro (talk) 17:56, 18 April 2010 (UTC)

You can perform chemical analysis on the charge to estimate total released energy, but the purpose of such testing is to account for "non-ideal" characteristics. Take a look at ballistics - particularly internal ballistics (although all the various categories are relevant). Some firearm muzzle velocity can be measured with RADAR - especially if the projectile is large (though it can also be applied to smaller munitions). Here's a RADAR to measure ballistics for large artillery. Nimur (talk) 17:55, 18 April 2010 (UTC)

You can measure the speed directly using a high speed camera too. SteveBaker (talk) 21:05, 18 April 2010 (UTC)

ocean currents

why do most of the warm ocean currents flow along east coast while cold currents flow through west coast? —Preceding unsigned comment added by 117.200.67.69 (talk) 17:35, 18 April 2010 (UTC)

Which coasts do you mean ? The US ? StuRat (talk) 17:45, 18 April 2010 (UTC)

The relevant article is boundary current. These processes result from the Coriolis effect. There are some exceptions to the general rule the OP has identified, because geography is complex and ocean currents are affected by many interacting parameters. Nimur (talk) 17:57, 18 April 2010 (UTC)

Coriolis by itself doesn't do it. The main reason is that the ocean's movement is 'forced' by the prevailing winds which are from east to west at the tropics (trade winds) and from west to east at temperate latitudes (westerlies). Dauto (talk) 18:39, 18 April 2010 (UTC)

True, but Coriolis is responsible for the lateral components of both trade winds and westerlies. Dbfirs 20:08, 18 April 2010 (UTC)

See Gulf Stream, Labrador Current and California Current for details on specific currents around the US. ~AH1^(TCU) 00:59, 22 April 2010 (UTC)

bond formation of SiO

what type of bonds involve in SiO(Silicon mono oxide).If they are different to CO (Carbon Mono Oxide ) plz give explaination.--True path finder (talk) 19:57, 18 April 2010 (UTC)

I would expect they are the same as carbon monoxide (CO): One O⁺ with a triple bond to a C^-. --The High Fin Sperm Whale 21:11, 18 April 2010 (UTC)

The silicon monoxide article would be a good place to find this information. Not every property or bonding pattern from carbon structures is identical. DMacks (talk) 14:09, 19 April 2010 (UTC)

single crystal chalk (kitchen chemistry woohoo!)

My friend wants to know if powdered chalk can reconstituted into more solid chunks of chalk. (It's magnesium carbonate.) It's basically for more convenient handling as gymnasium weights, rather than any sort of blackboard-writing. My current plan is to dissolve the chalk in boiling vinegar, and then slowly distill it over a long period (an hour?). Will this work? John Riemann Soong (talk) 21:31, 18 April 2010 (UTC)

Do you mean chalk, gypsum or magnesium carbonate? The stuff you write on blackboards with, despite the common name, is gypsum. Neither gypsum or chalk is magnesium carbonate. Chalk is calcium carbonate and gypsum is calcium sulfate dihydrate. I'm not sure any of them will dissolve in vinegar. They will react with it and become some other compound, so distillation wouldn't get it back. To get it to form a large crystal you probably have to heat it up a lot until it melts (probably without exposing it to oxygen, or anything else it might react with, in the process) and then cool it slowly. (The melting point of chalk is 825°C, so not easy to reach.) --Tango (talk) 22:04, 18 April 2010 (UTC)

{ec}You will decompose it to magnesium acetate, and carbon dioxide will escape. You may be able to crystalise that salt however and then carve it into a weight, as it will not be very hard. However don't expect it to be too strong either! It is likely to be brittle. You will need a lot of vinegar to do this. Tens of liters. Melting it will not be a kitchen capability. It is easier to melt lead or solder in the kitchen if you want to make weights. Graeme Bartlett (talk) 22:07, 18 April 2010 (UTC)

The "chalk" I usually see in gyms and billiard-halls is more of a compressed chunk of powder rather than a single crystal. A single crystal would probably be hard, have a clean geometric shape, and be translucent/transparent rather than an amorphous powdery opaque blob. DMacks (talk) 22:16, 18 April 2010 (UTC)

Well I meant gymnasium chalk MgCO3. AFAIK I would get magnesium bicarbonate if I dissolve at a low pH, which is water soluble. I also expect boiling water to help me dissolve the rest. Completely protonating magnesium carbonate to carbonic acid + magnesium acetate is likely to be difficult, naturally. John Riemann Soong (talk) 00:40, 19 April 2010 (UTC)

magnesium bicarbonate is not very stable and you really need to have a high pressure of carbondioxide to counter the decomposition. Heat would help the decomposition by boiling off carbon dioxide, and you are more likely to get a crust forming than a single crystal. Graeme Bartlett (talk) 09:08, 19 April 2010 (UTC)

If all you need is weights, why not just mix it with a small amount of glue? And why chalk for weights anyway? I can think of lots of other materials that might be better. Ariel. (talk) 09:15, 19 April 2010 (UTC)

Completely protonating magnesium carbonate to carbonic acid + magnesium acetate is not difficult at all (this will happen when you dissolve it), and will result in a lot of CO2 being released. This works for any carbonate or bicarbonate salt.24.150.18.30 (talk) 01:21, 20 April 2010 (UTC)

Is there any way to trigger weak polymerisation? John Riemann Soong (talk) 20:54, 20 April 2010 (UTC)