Wikipedia:Reference desk/Archives/Science/2013 July 22

= July 22 =

MInimal human sustaining-crops?
Is there a list or lists of standard crops, like "wheat, corn, and broccoli" or "rice, beans, and spinach" (without special varieties, like golden rice) that would be a minimum for sustaining human life without supplements or malnutrition? A list with standard meat/products animals like cattle or chicken would be acceptable. I am looking for an absolute minimum healthy set (no malnutrition, no forced eating of greens) as a premise for a story of human colonists. Thanks. μηδείς (talk) 02:06, 22 July 2013 (UTC)


 * If you're talking about a sci-fi story, the scenario you propose is exceedingly implausible. Any colony is going to be supplied with hundreds of different plants, and probably a couple dozen animal species as well.
 * Why? Reliance on a minimal number would provide no safety net should one of the crops fail to thrive. Also, a minimal diet would be so monotonous and boring that the colonists would soon commit suicide.
 * Furthermore, in a future sci-fi setting, you can bet your bottom dollar that the plants and animals accompanying the colonists will be genetically modified to beef up production, nutrition and palatability. They won't resemble the fruits and vegetables you get in the store now any more than the vegetables you get in the store now resemble their ancestors from a thousand years ago or more. Expecting space colonists to be carrying heritage varieties with them strains credibility. Dominus Vobisdu (talk) 05:04, 22 July 2013 (UTC)
 * Of course, but research would begin with a core of animals and plants, they might then modify them and add upon them. You wouldn't assume 100 earth species and then, during flight, say, oh, fuck, we didn't really need wheat, rye, and oats, and we forgot a source of vitamin A.  I am thinking cows, chicken, beans, corn, and spinach will provide humans all the vitamins, fats, proteins and minerals.  Dogs and horses to manage the animals, and as companions: then, say, caffeine in some source, opium and marijuana.  It is easier to criticize and expand on such a list than to start with 100 and work backwards.  The idea seems so obvious I was hoping some one would have a source from NASA or some environmentalists. Starting with what five organisms or less get me every vital nutrient give us a solid base.  μηδείς (talk) 06:05, 22 July 2013 (UTC)
 * You could survive indefinitely on just two foods: eggs and lemons. Eggs contain practically every nutrient you need, except vitamin C. That's where the lemons come in.
 * Also, if you're taking animals, you'll need plants to feed the animals.
 * Another thing to consider is that any plant or animal (or bacterium, fungus or alga) can, at least theoretically, be genetically engineered to provide exactly the right balance of all essential nutrients. We may not be at that stage yet, but by the time space colonization becomes feasible (well over 100 years from now), that will have certainly already long been accomplished, and we can send off our colonists with a single species.
 * Here are some articles I found with a quick Google search: [], [], [], []. There are plenty more that discuss the problem in great detail. Dominus Vobisdu (talk) 07:00, 22 July 2013 (UTC)
 * I have read those sources. The main issue is they seem to be assuming high tech/possible gentic manipulation, and survival in space, while I am more interested in low tech under earthlike conditions,say, being stranded on the Kerguelen Islands with slightly better climate conditions and an inability to rely on the native life. μηδείς (talk) 19:35, 22 July 2013 (UTC)


 * Eating nothing but eggs supplemented with a little lemon would be a very bad idea. Eggs have zero dietary fiber, so you'd wind up with constipation, and likely also wind up with other intestinal problems like diverticulitis and colorectal cancer; see Dietary fiber.  Eggs also contain only about 2% of their calories in the form of carbohydrates, which would make the diet an extreme version of a low-carbohydrate diet.  Nutrition organizations recommend getting most of your calories from carbohydrates (see Carbohydrate), and in general make moderate-to-strong statements in opposition to even moderately low-carb diets, which still provide about ten times as much carbohydrate as an all-egg diet would (see Low-carbohydrate diet.  Eggs are also sky-high in saturated fat and cholesterol, which give you cardiovascular disease and cancer; see Saturated fat and Hypercholesterolemia.  The saturated fat and cholesterol in an egg are concentrated in the yolk, so you could reduce that problem by switching to more egg white, but the resulting even higher excess of protein would worsen your ketoacidosis.  For more on the health problems associated with eggs, see Egg (food).  Do not try this diet at home, kids.  Red Act (talk) 21:19, 22 July 2013 (UTC)


 * This brings up a good point. "Malnutrition" typically only refers to a lack of required nutrients, but perhaps it should also refer to an overabundance of bad actors, like LDL cholesterol, trans fats, saturated fat, sodium, sugar, and alcohol.  Historically, it was the lack of nutrients which was the common problem, but now we are having as much of a problem with too much, so need to re-evaluate the word "malnutrition". StuRat (talk) 21:31, 22 July 2013 (UTC)


 * If we consider eggs, maize, and spinach as below, that's plenty of carbs and fiber. And, of course, one need not eat the yolks--they can actually be fermented and used for fertilizer for the corn, no? μηδείς (talk) 00:16, 24 July 2013 (UTC)


 * Your question cannot realy be intelligently answered without you supplying further information. The infamous "bread and water" will do for a short trip, but definitely not for a reasonable lifespan.  The average person can go without any vitamin C for about 6 to 8 weeks without any ill effects unles there is infection or injury.  It was not until the major European navies and merchant fleets started long world-wide voyages about 300 years ago that the need to take citrus and other foods containing vitamin C became apparent - voyages within the mediteranian for example were not long enough for survey to appear.  A lot of what makes a varied diet goes toward goes toward sustaining a really good immune system and injury repair.  If your travellers have been and are quarantined, they do not need a good immune system. Further, is life to be merely sustained (nobody dies), or maintained at a high level of fitness?  Persons undergoing a high level of physical activity and/or a high level of mental stress need a better diet than those who are couch potatoes - it definitely NOT just a case of kilojoules.  If more than one generation is to be sustained, or there are children or pregnant females, the diet must have significant calcium.  Things like flouride and folate need to ensured.  124.178.151.10 (talk) 07:16, 22 July 2013 (UTC)


 * The IP user presumably meant to spell Scurvy, the disease resulting from a deficiency of vitamin C. DreadRed (talk) 09:30, 22 July 2013 (UTC)


 * The answer depends on how cruelly and heartlessly you want to treat your colonists. Most of the world's agrarian population, throughout most of human history, survived on only a few staple foods.  They may not have had the prettiest bellies or the smallest thyroid glands, but even the most severe famines didn't wipe out the entire population, and that's all you need for a colony.
 * A few historical examples: prior to the Irish potato famine, the potato was the only staple crop for the Irish. Poorer peasants ate almost literally nothing but potatoes, with only very small amounts of fish and oatmeal .  Recently, a man ate nothing but potatoes for 2 months and experienced no ill effects .  Some Indian groups in North America primarily planted and ate the Three Sisters (agriculture): maize (corn), squash, and beans, which complement each other nutritionally.
 * I don't think calcium, fluoride, and folate need to be ensured for "children or pregnant females". Keep in mind that for virtually all of human (pre-)history, nobody even knew what calcium, fluoride, or folate were, let alone how to ensure they got enough.  If children die, too bad, the women can make new ones.  If pregnant women don't get enough nutrients, they can engage in cannibalism or walk around with some broken bones--either way, the human population will eventually settle to an equilibrium where people are not starving to death faster than babies can be born.  If this scenario seems too heartless--and keep in mind it was the normal condition of most agriculture-dependent human populations before modernity--add food resources until the happiness vs. cost ratio is at an acceptable level.  --Bowlhover (talk) 09:13, 22 July 2013 (UTC)
 * You may get some ideas from what they did in the Biosphere 2 experiments. According to our article the first mission got 83% of its diet from their crops of bananas, papayas, sweet potatoes, beets, peanuts, lablab and cowpea beans, rice, and wheat.  They also had animal products (milk, eggs, chicken) according to .  However, it proved impossible to keep the first mission completely sealed due to carbon dioxide build up.  It's fascinating how badly a bunch of ordinary couch-potatos Americans coped with a minimal diet.  They also suffered from some interesting side-effects such as turning orange due to an excess of beta-carotene.  The second mission solved the CO2 problem by sealing the concrete floor (the source of the problem) but our article unfortunately does not give much in the way of diet for the second mission.  This article will have the details but it is behind paywall.  Spinning  Spark  10:17, 22 July 2013 (UTC)


 * I am looking for a minimal diet that would physiccally sustain a healthy, reproducing colony on a permamnent basis, all other things considered equal. (I.e., no weird sun or soil deficiencies, or weird diseases.)  For example, if we started with "chickens, corn, and spinach" which has been suggested as sufficient above, adding a milk producer will add milk, cheese, butter, ice-cream, and yougurt assuming a culturing agent is available.  Corn will provide oil, corn syrup, grain alcohol, and flower and feed for the animals.  We then have cakes and fried battered food.  That's all with only four starting crops.  That will keep you fairly healthy mentally, with a few other crops thrown in like coffee, marijuania, opium, nicotine, and other medicinals possible.  POrk and a culturable seafood item will do well to round out meatn needs and nutrients typical of seafood. The question then is, will the animals need greater fee variety than the corn and spinach? μηδείς (talk) 17:22, 22 July 2013 (UTC)


 * What do you think of my suggestion, potato + oatmeal? That's enough to ensure the essential nutrients, and the Irish showed that it works.  (The potato famine was due to a "weird disease", one that didn't previously exist in Europe.)  Failing that, maize + bean + squash works too, and has also been tried historically.  --Bowlhover (talk) 18:28, 22 July 2013 (UTC)


 * @Medis: Read or watch Guns, germs and steel for a very good description of what happened when the Dutch tried to settle tropical Africa sticking with the temperate crops and farming methods they were used to. A lot will depend on the climate and soil conditions of the colony site. That is one reason why any possible space colony is going to be provided with seeds or seedlings of hundreds, if not thousands, of species to provide back ups when certain crops fail to thrive.
 * I'm a bit confused where you are sending this colony and when, and why. Like I said, in the near future, we are going to have an enormous capacity to modify plants and animals to fit both our needs and the conditions of the colony site. It is highly improbable, and downright implausible, to think that a civilization that is advanced enough to establish space colonies is going to establish them on a shoestring, minimum basis as your expecting, as if they were 18th century pioneers. Even they, and the potato-chomping Irishmen mentioned above, had a diet consisting of several dozen plants and about a dozen animals, domesticated and wild. The scenario you're presenting is unrealistic for a future space colonization, for a whole host of reasons.
 * If this is some type of penal colony where you don't care about their mental well-being and whether they have back up plants or not, you could get away with a semi-vegetarian diet consisting of a grain like corn, a legume like beans, a leafy grean like broccoli or kale, a fruit like tomatoes or cornelian cherries, maybe with an animal species like chickens, rabbits or fish thrown in. The colony would survive indefinitely, provided the plants and animals selected could thrive at the colony site. Less than that, and you're getting into the realm where the diet would be so monotonous that people would eventually lose the will to live and start failing to thrive and reproduce themselves.
 * Perhaps you can flesh out the scenario you are thinking of a bit. Right now, we're just stabbing in the dark. Dominus Vobisdu (talk) 19:29, 22 July 2013 (UTC)
 * In response to Bowlhover, knowing you can survive on oatmeal and potatoes alone is interesting, although I would suspect certain fats and vitamins might lack. But it would indeed be a suicidal meal for me.  :::In response to Dominus, the concern is purely intellectual.  I started thinking about it after I turned the lights off a few nights ago.  I am basically assuming a land similar to South Jersey or Long Island with a soil with similar nutrients but no native earth life.  The colonists are not rich, but in a Noah's Ark situation, where they need to know what is the absolute minimum ecology and crops that will sustain them.  I think replenishing the soil and feeding the animals will be more important than I first assumed above. (They will probably obviously need nematodes, ants, fungi and an ant predator as well.)  Something along the lines of Larry Niven's Destiny's Road but a bit more hospitable as far as essential soil nutrients.  I don't know if chickens can control ants.  It all works out to a big game of rock, scissors, paper, lizard, Spock. μηδείς (talk) 19:50, 22 July 2013 (UTC)


 * It seems to me that using animals here makes zero sense. The animal has to be fed - and probably requires the same degree of sophisticated nutrients that you and I do - and an animal is a pretty inefficient way to convert sunlight, air, water and trace-elements into food.  So the question mostly becomes one of how you're going to maintain the soil in good shape.  Recycling human waste into fertilizer will work - but in any such process, there would be a gradual loss of material so that after enough years, there wouldn't be enough waste to replenish the soil with some critical substance or other.  Much depends on how earth-like the planet is.  Does it have the (effectively infinite) reserves of all of the trace elements in it's crust?   The earth is effectively a closed system...you can consider that (say) magnesium in the soil goes into the plants and from there into animals and from there back into the soil with zero loss.  But in a small colony of a few hundred acres on a gigantic, barren planet - the material would gradually be lost out into the bigger environment.  If the soil on Planet-X doesn't have much magnesium in it - then over enough generations, you'd be in big trouble.


 * A lot also depends on energy supply. If the colonists have a large fusion reactor, crazy-large numbers of solar panels or some kind of sci-fi unobtainium-based power supply - then if they are sufficiently technologically savvy and have some initial manufacturing capability - they can make robotic mining machines to sift through millions of tons of soil to get the trace elements they need to replenish their fields.  With enough energy, there are chemical pathways to make almost all of the nutrients that humans need from raw materials.  Heck, we can make synthetic baby formula that'll keep a kid alive and healthy for a couple of years with nothing but water - I doubt that adult nutrition is that much harder.


 * So, IMHO, this isn't a matter of finding the three, five or fifty plants - it's a matter of coming up with a complete picture of how this colony works. What is the native soil like?  What is the native atmosphere like?  How much energy do you have just lying around?  How constrained is the population...for example, if you all live in a dome and never leave - then you can recycle the air and water fairly effectively.  But if everyone lives in mud huts out by their fields, then all sorts of chemicals will be rapidly lost to the larger environment and be almost impossible to recoup.
 * SteveBaker (talk) 15:39, 23 July 2013 (UTC)


 * also, the picture of complete nutrition that can be sort of assembled from scratch for humans is sort of illusory; we're always coming up with new items in food, the lack of which may not kill you straight out or make you obviously sick within a short time, but which seem to be beneficial towards a long healthy life; antioxidants, omega-whatevers, etc.; stuff that modulates your immune system, your inflammatory response, fights tumors, etc. Our evolutionary ancestors got them from a wide and varied diet of scavenging whatever they could find, and of course as we moved through agricultural food sourcing we see from archaeology evidence of nutritional deficiencies on a gross scale, then as we learned about how to fix that, we moved to industrial food sourcing as we do it today with attendant new but less severe nutritional deficits (as well as all the obvious problems of fats, sugars, sodium, etc. overdosing), so we haven't gotten to the bottom of all those micronutrients and so on. Yet, mankind seems determined to get past the odious biological mandate to eat lots of fruits and vegetables, by abstratcting the list of whatever biochemicals they contain and putting them in pills. But anyway, my semi-learned assessment is that our species is evolved to eat lots of berries and cabbages, for optimum health. I'm speaking of the larger families, so that berries would include tomatoes, for instance, and cabbages includes all the mustards and cabbagey/mustardy greens and broccoli and turnips and so on. These are the foods that keep popping up when somebody discovers a new phytochemical or phenol or something that has beneficial effects, not to mention being heavily laden with vitamins (including our specifically needed vitamin C, that's a clue as to what our evolutionary ancestors ate). Gzuckier (talk) 16:22, 23 July 2013 (UTC)


 * (ec) To clarify, I am not asking what they will eat on the ship or for the early period when starting. I am talking about the number of species as the only limit for a long term self-reproducing colony. Under earthlike-conditions on a planet with soil like ours, but, say, the wrong chirality in its proteins and a lack of suitable sugars and necessary fats.  There were no space or sunlight limitations, I have not asked for a link to NASA or an environmentalists' stats on sunlight and space requirements.
 * Arguments against animals may come from other motives, but nutritionally, a chicken is a concentrator of nutrients. Apparently from the claims above one can survive on corn, corn-fed chicken, and spinach.  That's three species, quite a bit of variety from the chicken and corn, and a heck of a lot more variety if you add cattle.  Obviously you'll have to live on reserves before you've got enough corn planted and harvested and enough adult animals, but I am looking at a self-sustaining long term colony without other resource limits.
 * The open questions are, can cattle and chicken survive on corn and spinach, or is another plant crop necessary, and then, what few added crops will add the most nutritional and mental variety. I'd think wheat, tomatoes, swine, peppers, broccoli, beans, crabs and fish or clams if they can be cultured on detritus or algae, and bonus crops like tobacco, hemp, coffee, etc., might give the best variety for the least number of actual species. I have no idea of what Eastern/african crops I may be missing.
 * I am still kind of surprised there are no "lists" or other sources out there that have addressed this. A vegetarian list could work great if supplemented by a few animals. μηδείς (talk) 16:33, 23 July 2013 (UTC)


 * Yeah - but you're forgetting that a space-faring colonist could easily have access to cheap energy and a sophisticated knowledge of chemistry. I bet that if you got enough chemists and nutritionalists together in one place - and told them that they had a feedstock of some kind containing all of the basic elements (oxygen, carbon, hydrogen, nitrogen, trace-metals, etc) then they could come up with chemical pathways to make just about any nutritional chemical we'd ever need.  Given that, I don't see why you necessarily need any plants or animals at all.  Synthetic flavorings and fancy ways to fake texture would allow almost any basic feed-stock to feed your colony with a varied and interesting diet without any kind of farming whatever - providing there is enough energy available and factories for the manufacture can be built before the colony runs out of whatever survival rations they brought with them.


 * So the true and correct answer is zero...given enough energy and a reasonable level of technology.


 * Now, if you stipulate that there is not sufficient energy or technology - then the answer starts to depend more and more on how little energy or how little technology there is. If our colonists have somehow been reduced to getting energy from burning waste from their crops and farming with basic wood and stone implements - then your answer will be VERY different.  But if they have the ability to do some basic science, they can get away with less crop varieties.


 * My bottom line is that to get a good answer, you need to be MUCH more specific about what resources the planet has (eg, Is there free CO2 in the atmosphere? Is there ample sunlight?  Does it have water in liquid form?  What food storage technology is available to cover the winter months (or the summer months if the place gets really hot)?   Does the planet have a decent magnetosphere and ozone layer to deflect harmful radiation from the local star?   Does that star shine in the light frequencies that earthly chlorophyll can thrive on (eg Bad luck if the star is a red dwarf!).


 * SteveBaker (talk) 02:32, 24 July 2013 (UTC)


 * I have answered these questions explicitly, several times: standard unmodified crops (implying I expect such to be sewable and harvestable), earthlike conditions (twice), like New Jersey or Long Island but with native life of perhaps the wrong chirality, etc. I assume that covers free CO2 and sunlight.  The only variable I am interested in is the choice of crops, the rest is assumed "standard" temperate conditions and so forth. You might as well recast the question as, if someone were to survive as healthy and happy as possible for a year in England on the produce of only three species (macroscopic ones--assume commensal bacteria and fungi) what three (or five or ten) species would he be best off choosing? μηδείς (talk) 00:34, 26 July 2013 (UTC)

Wasp-eating birds
What species of birds that are widespread in the USA (if any) are known to make wasps/yellowjackets/hornets a significant part of their diet? 24.23.196.85 (talk) 04:38, 22 July 2013 (UTC)
 * Bee-eater is likely what you look for as its eating flying insects but it seems they are spread everywhere exept in the USA. --Kharon (talk) 17:31, 22 July 2013 (UTC)


 * New World oriole Hcobb (talk) 19:15, 22 July 2013 (UTC)
 * The Northern shrike not only eats wasps, but impales them first. If you're looking to send a message to any bothersome insects, this is the bird you want. InedibleHulk (talk) 00:44, 25 July 2013 (UTC)


 * Sadly, the "Northern" part refers to Northern Canada, not Northern US. (I completely overlooked what migratory birds do.) The Loggerhead shrike seems to be common enough in the US, though too. InedibleHulk (talk) 00:48, 25 July 2013 (UTC)


 * Thanks! 24.23.196.85 (talk) 01:18, 27 July 2013 (UTC)

Phosphates
At what temperatures to phosphates generally decompose at? What do they sequentially decompose to? How do they behave under electrolysis? (You'd think that this basic information would be found in Phosphates, apparently not). Plasmic Physics (talk) 11:32, 22 July 2013 (UTC)


 * Part of using Wikipedia effectively is learning to use an article to find an external resource. In the case of well-known chemicals, you can usually find safety and handling information in the material safety data sheet that is kept by your institution, school, or corporation; or if you don't have one, from the company who supplies your materials.  For example, Fisher Scientific maintains an MSDS for, e.g., potassium phosphate.  It lists the approximate decomposition temperature and products.
 * If you check the MSDS for any other specific phosphate compound, you will probably find the decomposition temperature and products. Many phosphates decompose into hazardous gas or emit toxic fumes.
 * If you worked at a place that often performed electrolysis of phosphates, your organization would be wise to keep a current and informative MSDS in a place where you could easily get access to it. Nimur (talk) 15:24, 22 July 2013 (UTC)


 * MSDS sheets are notoriously vague, and they mention nothing on electrolytic habits. Plasmic Physics (talk) 02:44, 23 July 2013 (UTC)

Isostearamidopropyl Morpholine Lactate
I see this ingredient used in some body wash products. But the only info I can find online is that it's an antistatic agent. What benefit would an antistatic have for a product designed to wash mostly hairless human bodies? (I never thought static flyaway body hair was a problem to begin with.) --157.254.210.11 (talk) 16:28, 22 July 2013 (UTC)
 * It's a cationic surfactant which is probably more the reason it is used in body washes than any antistatic property it may have. It has also been suggested that it may be useful in removing lead from contaminated soil.  Spinning  Spark  16:48, 22 July 2013 (UTC)


 * Hmm...this toxicology report says that it is an antistatic in hair care products. So it probably has different uses in different products.  Spinning  Spark  16:52, 22 July 2013 (UTC)

Can lime juice "cook" shrimp ?
I saw a cooking show which advised only leaving shrimp soaking in lime juice for a few hours max, as otherwise, the lime juice might "cook" the shrimp. Sounded like total BS to me. So, is there any definition of the word "cook" for which their statement might be considered correct ? StuRat (talk) 19:10, 22 July 2013 (UTC)


 * The lime juice will denature the meat which is what cooking does to meat. There are various tender meats cooked or pickled in various acids, especially fish, which you can google. μηδείς (talk) 19:22, 22 July 2013 (UTC)


 * See Ceviche. Dominus Vobisdu (talk) 19:29, 22 July 2013 (UTC)


 * From the Cooking article: "Cooking can also occur through chemical reactions without the presence of heat... with the acids in lemon or lime juice.” Food_preparation has a list of chemical cooking techniques. Marination says “In meats, the acid causes the tissue to break down,” changing the texture via chemical reaction. 198.190.231.15 (talk) 15:08, 23 July 2013 (UTC)

Interesting answers. Unfortunately, this type of "cooking" doesn't seem to kill off bacteria, which is the main reason to cook things, as far as I can see. StuRat (talk) 18:24, 23 July 2013 (UTC)


 * It should also be noted that much (not all, but much) bacteria comes from food being dead for a longer period of time. Fresher food is on the balance safer, and if food is reliably and properly handled from the time the animal in questions kicks it to when you eat it, there are many safe, raw foods.  Besides the aforementioned ceviche there is also sashimi, raw bars, tartare, kibbeh nayyeh, sannakji, etc.  The unsafety in these dishes is greatly reduced by a) reducing the time between the death of the critter being consumed and you consuming it and b) proper handling in times between death and consuming.  In the case of raw bars, your usually eating food which isn't really properly dead yet, merely numb a bit.  Is there a greater risk, comparitively, between these foods (properly prepared) and, say, food that is cooked thoroughly?  Probably.  Does that mean that the risk is unacceptably higher?  That's up to an individuals own risk tolerance.  It should be noted that many people do eat this foods commonly; while to many North American and Anglophone peoples they seem a bit outside of the normal cuisine, for many people these are as common as hamburgers or pizza is to Americans.  If it was an outrageous risk, ut'd be doubtful if these dishes would be as common as they are.   One reference: "The cases of sushi-related illness fall far below the number of people sickened by contaminated produce such jalapeno peppers. Even in those rare cases, the rice in sushi is more often the culprit than the fish."   -- Jayron  32  21:38, 23 July 2013 (UTC)


 * There could certainly be an argument that people will cut corners on safety for food they know will be cooked before it is served, possibly making it even less safe than raw food. For example, contaminated hamburgers may remain dangerous after cooking, unless well-done. StuRat (talk) 21:54, 23 July 2013 (UTC)


 * Interesting that you use scare quotes for cooking that doesn't use heat. People often refer to the fish that Japanese and others eat as "raw", but that's wrong. Just because heat hasn't been used in the preparation, that doesn't mean the food is raw or uncooked.  --   Jack of Oz   [pleasantries]  23:40, 23 July 2013 (UTC)


 * I am not sure whether Stu's right acid doesn't kill bacteria, but his scare quotes are fine given that cook comes from a good PIE root *pekw-, meaning to prepare food with heat. μηδείς (talk) 00:08, 24 July 2013 (UTC)


 * Considering all the nasty things I've seen growing on citrus fruit, I don't think I can consider anything marinated in it to be sterile. StuRat (talk) 00:42, 27 July 2013 (UTC)


 * Etymology is one thing, meaning is another. I know that "to cook" is generally a synonym for "to prepare food using heat".  But, as 198.190.231.15 reminds us above: "Cooking can also occur through chemical reactions without the presence of heat...".  --   Jack of Oz   [pleasantries]  01:27, 24 July 2013 (UTC)


 * Says who? The first line of our article on cooking says "Cooking or cookery is the art or practice of preparing food for consumption with the use of heat" and, based on my admittedly limited experience, if you asked a hundred people what cooking is, approximately 100 of them would use the word "heat" in there somewhere. Matt Deres (talk) 02:20, 24 July 2013 (UTC)


 * Read the whole paragraph. Then ask 100 Japanese people what cooking is.  --   Jack of Oz   [pleasantries]  05:15, 24 July 2013 (UTC)


 * :-) A hundred Japanese people would say the same thing; they use fire for cooking over there as well. Claiming that sushi is "cooked" because it's been in contact with vinegared rice for the thirty seconds it takes to walk it to your table seems outrageous, and indeed the sushi article consistently refers to the fish as usually being "raw". If you want to call something like ceviche "chemically cooked" then that's cool, but you need to have that qualifier in there; cooking is about a lot more than denaturing some of the muscle proteins. Matt Deres (talk) 11:00, 24 July 2013 (UTC)

The question about the Japanese is beside the point, since cook is not a native Japanese term.
 * As for to cook < PIE *pekw "to prepare food with heat" we have:
 * Tokharian: A, B päk- 'cook, boil, ripen' (PT *päk-) (Adams 368)
 * Old Indian: pácati, ptc. paktá- `to cook, bake, roast, boil'; pácyate `to ripen', pakvá- `cooked, baked, ripe', paktí- f. `cooking, preparing food; food, cooked food', paktár- `cooking, roasting, baking', pāka- m. `cooking, baking, roasting'
 * Avestan: pačaiti `kocht, bäckt, brät'; nasu-pāka- `Leichen(teile) kochend, verbrennend'; Pashto poχ `gekocht, gar, reif'
 * Armenian: hach `Brot' (< *pokʷti-)
 * Slavic: *pekti, *pekǭ; *pektь; *pekъ; *potъ; *o-pokā
 * Baltic: *kep- (*kep-a-) vb., *kep- vb. intr.
 * Latin: coquō, -ere, coxī, -ctum `kochen, sieden, brennen, reifen', coquus, -ī m. `Koch', coquīna f. `Küche', coctus, -a `gekocht'; coctor, -ōris m. `Koch'; coctiō f. `Kochen, Gekochtes', praecox `frühreif'
 * Celtic: *hekʷ-, *hekʷto- > Cymr poeth `heiss'; pobi `backen'; popuryes `pistrix', Corn pobas `backen'; peber `Bäcker', Bret pobet `backen'; poaz `gekocht'; pober `Bäcker'
 * Albanian: pjek `ich backe'
 * as well as
 * Uralic *päkkV "hot" (Saami, Nganasan Samoyed.)
 * Tungus-Manchu *peku "hot"
 * Korean phuk-ha "hot"
 * Kartvelian: Svan. -puḳv- / -pḳv- 'to dry'
 * Dravidian: *paɣal- (or to *ṗVxwV "fire")

μηδείς (talk) 20:00, 24 July 2013 (UTC)

How accurately known are the orbits of Space debris?
Space debris talks about the size of debris that can be tracked and the distance. But how accurately known are their positions? I didn't see that info in the article and I think I remember hearing that they would change the orbit of the shuttle if it was to come within 2 miles of known debris, which seems very large. Bubba73 You talkin' to me? 19:24, 22 July 2013 (UTC)


 * See SATVIEW - Tracking Space Junk in real time.
 * —Wavelength (talk) 19:32, 22 July 2013 (UTC)


 * See NASA - Space Debris and Human Spacecraft: Planning for and Reacting to Debris.
 * –Wavelength (talk) 20:10, 22 July 2013 (UTC)


 * According to http://issfd.org/ISSFD_2012/ISSFD23_CRSD2_3_abstract.pdf, "for a radar tracking scenario comprising of 6 passes within a 36 hours period a remarkable orbit determination accuracy of 10 m in radial / normal direction (1D, RMS) and an accuracy of less than 60 m (RMS) in the along-track direction is computed from comparison to the reference orbit." (It is with some reluctance that I am quoting this passage, because I do not wish to perpetuate the misuse of the verb "comprise".  Please see User:Giraffedata/comprised of.  The source should have said "for a radar tracking scenario comprising 6 passes …" or another correct alternative.)
 * —Wavelength (talk) 20:27, 22 July 2013 (UTC)


 * The first one gives altitudes rounded to 0.01km, 10 meters. But that may or may not be the actual accuracy of the position.  The second one says that some of them aren't known very precisely.  If they know something is going to miss by 100 meters, then it seems to me that they don't need to worry about it.  Bubba73 You talkin' to me? 20:32, 22 July 2013 (UTC)


 * I subscribe to Orbital Debris Quarterly, a free email newsletter that keeps me up to date on all the latest news, charts, happenings, and state-of-the-art science related to orbital debris. If you're interested in tracking space debris, the most important question is how are you tracking space debris, not how accurately are you tracking space debris.  For example, if you're using ground-based optical telescopes, or ground-based RADAR, your methodology and capabilities are very different.  If you're using a space-based RADAR, your accuracy is much higher, but your range is limited to those objects within your line of sight.
 * If you want to simulate orbital debris, there are free engineering models and data sets. High position accuracy is traded off against a probabilistic model; the more accurate you want to be, the more uncertainty you must accept, based on available observation.  In principle, it is possible to describe a radar return with accuracy on the order of magnitude of the wavelength; so it is possible to use HAX data to provide centimeter accuracy.  But converting from a RADAR observation into an orbital description is a very complicated engineering problem, worthy of several years of study.  Nimur (talk) 20:58, 22 July 2013 (UTC)


 * I was thinking of NORAD and Air Force Space Surveillance System. The latter uses radar with a wavelength of a little less than 1.4 meters, so within a few meters?  Bubba73 You talkin' to me? 23:17, 22 July 2013 (UTC)

Two MRSA questions
Nyttend (talk) 22:11, 22 July 2013 (UTC)
 * 1) Why is a Staphylococcus aureus infection (resistant or not) bad for the human body? I attempted to read the "Virulence factors" section of the article, but it's technical to the point that I can't figure out if that section answers my question.  Guessing perhaps that the bacterium eats nutrients in the bloodstream or that its lifecycle produces chemicals that poison the body; I saw nothing to suggest that it's a parasite.
 * 2) Imagine two people of equal health/strength/physical condition/etc. that develop Staphylococcus aureus infections at the same time. One has a MRSA infection, and the other has "normal" bacteria that are vulnerable to treatment.  If the second person gets no medicine, can the two infections be expected to behave similarly, or will one patient probably come off worse than the other?


 * It can lead to chronic and intractable suppuration, to necrosis, gangrene, and (acute) sepsis. Many people are carriers, the problem being the occasion of their own or other's lowered immune state.  People getting elective surgery like my father's knee replacement are expected to test negative beforehand. μηδείς (talk) 01:01, 23 July 2013 (UTC)
 * No, I'm sorry, I wasn't asking what effects the infection can have. I was asking about the things the bacteria do that can cause those problems (and death).  This is similar to my "Mechanics of cancer death?" question at Reference desk/Archives/Science/2010 January 13.  Nyttend (talk) 02:42, 23 July 2013 (UTC)
 * According to the article you linked to, staph does this by producing toxins and by digesting living tissue. 24.23.196.85 (talk) 04:08, 23 July 2013 (UTC)
 * Toxic shock syndrome goes into some detail on the mechanisms of harm.  Acroterion   (talk)   14:52, 23 July 2013 (UTC)
 * Often, antibiotic resistance requires active measures such as beta-lactamase, which impose a small cost in terms of the protein that needs to be produced and secreted, but as that article explains MRSA actually has its own way for this effect, an alteration of PBP2a to make it simply avoid being inhibited by the drug. This, at least in this experiment  can attenuate virulence ... perhaps because you're designing a protein to do two things instead of just one.  Can you design a perfect protein that works as well (even better) than the natural form, while evading relevant antibiotics?  Likely.  Does it work that way for present MRSA?  You'd have to go through every single existing mutation and check each one to really know for sure.  But my guess is that most of the time, yes, there's a trade-off. Wnt (talk) 21:18, 26 July 2013 (UTC)