Wikipedia:Reference desk/Archives/Science/2017 January 24

= January 24 =

Why doesn't bariatric surgery lead to starvation?
What causes the weight loss after bariatric surgery to be limited so that you don't keep on losing weight and starve to death? After all, your stomach has been made so small that you can't even tolerate the normal amount of food that most people need to eat. Count Iblis (talk) 02:03, 24 January 2017 (UTC)


 * You have to be prepared to follow a special diet, focusing on protein as you main source of calories, followed by vegetables that provide vitamins, and then carbs. Very small roux-en-y gastric surgeries which left a stomach the size of a lemon are less popular now, the gastric sleeve (which I had done on Friday) leaves you with a stomach the size of a banana.  A woman I know who had the surgery (roux-en-y, 15 years ago) did eventually die from kidney and liver failure due to malnutrition.  Diet is key, and she ate fast food, and turned jaundiced as she starved to death.


 * You are expected to take vitamin supplements for the rest of your life, and your stomach will expand if you eat until fullness at each meal, which defeats the purpose of the surgery over the long run. Since I fasted on Thursday, I have not had to take any of my diabetes medicines.  Eventually I should be off my blood pressure and cholesterol medicines, which will pay for the cost of surgery in under two years, and add 18 years to my life expectancy.  (See the Northwest Mutual Life Expectancy Calculator.)


 * The big issue is keeping hydrated, since you have to drink about 64 oz of water and get 60 or so grams (more for men) of protein a day. So I have been drinking a quart of wonton soup broth and eating a quart of sugar-free jello made with a quart of protein-fortified water since then.


 * Basically, the bottom line is that this is not the sort of surgery you do without a lot of preparation, a long term commitment, and a support system where things like vitamin and protein supplements are available. I suggest you google bariatric diet at your favorite hospital's website, they will give reliable information.


 * μηδείς (talk) 03:59, 24 January 2017 (UTC)


 * Whole thing sounds like puppeteer birth control if you ask me. I still can't comprehend why, if people are willing to commit to this diet, they don't just go on it.  I mean, either you commit to it or you don't?  I don't follow the concept. Wnt (talk) 14:07, 24 January 2017 (UTC)
 * Is that an obscure Larry Niven reference, Wnt? Even if it is, I don't understand it, and either way it sounds potentially offensive, so perhaps you'd like to clarify? {The poster formerly known as 87.81.230.195}94.12.94.189 (talk) 15:32, 24 January 2017 (UTC)
 * Pierson's Puppeteers forbade contraception; the only allowable form was surgery. Hence, a trillion puppeteers. Anyway, bariatric surgery a last-ditch possibility for people who have tried everything else. --jpgordon&#x1d122;&#x1d106; &#x1D110;&#x1d107; 16:37, 24 January 2017 (UTC)


 * Puppeteer birth control if you like, but: (1) It is considered a last ditch option for the morbidly obese with co-morbidities such as diabetes type II; my body mass index is/was 35, (20 is normal) and I was diagnosed with type II diabetes in 2012. (2) You are expected to have dieted, which I have done lifelong (as well as at one point 1hr/ day on the stairmaster and rowing machine, yet was still 40 lbs over weight). (3) The surgery is a tool.  At this point I am full with two ounces, eventually I will be able to eat a lb of food a day, with three full meals of 4 ounces and two 2 ounce snacks (a slice of pepperoni bread is 2 ounces).


 * And (4), most importantly, the portion of the stomach removed includes the portion which produces ghrelin. Hence the gastric sleeve is actually a type of endocrine surgery; you're not just shrinking the bag, your removing a malfunctioning part of your endocrine system. One of the most intriguing consequences of the surgery is that patients’ blood sugar levels normalize within days—long before any weight loss has occurred. Patients can often stop taking their diabetes medication even before leaving the hospital.


 * I had the surgery at 2pm Friday, was home Saturday afternoon, am eating broth and jello, and can start yoghurt, cream soups, farina, scrambled eggs, and so forth tomorrow, most regular foods in two weeks. I don't feel deprived; I feel liberated.


 * μηδείς (talk) 18:08, 24 January 2017 (UTC)


 * Best wishes for an excellent outcome, Medeis! --Trovatore (talk) 22:05, 24 January 2017 (UTC)


 * Thanks, Trovatore. So far it has been miraculous, and a walk through the park.  (Of course I have been through 7 major surgeries, and this was my second time on a morphine drip, so I knew what to expect.)  But except for taking (needing) dilaudid for abdominal pain when I lay down to sleep, I am fully functional.  Even went to the library and grocery shopping today. μηδείς (talk) 23:35, 24 January 2017 (UTC)


 * Thanks Medeis for your explanations here! Count Iblis (talk) 00:47, 26 January 2017 (UTC)
 * Do read Fixing Dad: How Two Sons changed Their Father's Life by Jen Whitington (Short Books, 8 pounds 99 pence).   The review in Monday's Daily Telegraph says

"Diagnosed with diabetes in his early fifties, he now had many complications associated with chronically elevated blood sugar levels. They included poor circulation, peripheral neuropathy and a foot ulcer, as well as raised blood pressure and atrial fibrillation-for all of which he was taking no fewer than 10 different types of medication: ... Geoff, who, at 20 stone [280 pounds], was seriously overweight, is now five stone lighter, off all but one of those pills and has recently completed a 100-mile London-Surrey cycle ... 'Low-fat' means 'high carbohydrate'-wholemeal bread, pasta, rice and fruit-all of which is readily metabolised to sugar.   Geoff dispensed with them all in favour of meat, oily fish, dairy products and greens."

More at. 86.150.12.180 (talk) 17:38, 26 January 2017 (UTC)


 * Thanks, 86. I do agree entirely with the published medical advice on a low-carb diet (no rice, pasta, bread, potatoes), and had lost 70lbs; 40 by cutting out carbs, and 30 lbs that I had gained when put on insulin by going off insulin.  (I was still taking oral meds and went on liraglutide, a synthetic Gila Monster venom.)
 * But eventually after a year of weight loss I reached a plateau, hence my endocrinologist brought up the subject of the gastric sleeve. At this point I am now 10 days without any diabetes meds at all, am consuming about 20g of sugar (mostly lactose) daily, and expect to be down to the weight I was in 1996 within the next week. μηδείς (talk) 19:26, 28 January 2017 (UTC)

Brothers and sisters in dog packs
I cannot find this at Dog behavior.

In a (wild) dog pack, do brothers and sisters have babies together? Anna Frodesiak (talk) 02:55, 24 January 2017 (UTC)
 * I've been trying to find good information on this by searching "Dhole" (Indian wild dog) social structure, and "African wild dog" (Also called "Cape Hunting Dog") social structure, but have run out of time. You could follow these leads. They have both been studied extensively. 49.197.122.249 (talk) 08:42, 24 January 2017 (UTC)
 * Depending on what is meant by "wild dog", there are several different canines that could be so described. Wild canis lupus are generally called wolves, which would be the wild relative to the domestic dog.  There are also feral dogs, which are different, as well other species of canine also called "wild dogs", such as the African wild dog or Lycaon pictus.  This article from 2012, seems to indicate "no" for Lycaon pictus.  -- Jayron 32 14:22, 24 January 2017 (UTC)
 * This study suggests "rarely". --jpgordon&#x1d122;&#x1d106; &#x1D110;&#x1d107; 16:30, 24 January 2017 (UTC)

Thank you all. Anna Frodesiak (talk) 19:52, 24 January 2017 (UTC)


 * I wonder whether there's a difference between littermates and other siblings. —Tamfang (talk) 07:14, 26 January 2017 (UTC)

milk tooth
Which of the non-human mammals have elementary teeth,once those teeth fall and again new  teeth replace.--Akbarmohammadzade (talk) 04:18, 24 January 2017 (UTC) Milk tooth
 * Our article Diphyodont which is linked to from milk tooth mentions a small number but also makes it clear it applies to most mammals. So an exhaustive list is unlikely. In terms of mammals, it's probably more useful to ask which ones aren't diphyodont. Polyphyodont lists some. Monophyodont may lists others but it seems we don't even have an article, perhaps because it's relatively rare. Nil Einne (talk) 05:41, 24 January 2017 (UTC)


 * One of the most important themes of mammal evolution has been the development of a mechanism allowing us to both bite and chew with precision. Birds and reptiles bite, but they do not chew.  The alligator's teeth are simple alternating pegs made for grabbing and tearing.  Mammalian teeth line up in a set pattern that developed as mammals evolved from therapsids.  The incisors nip, the canines grab, the premolars (also carnassials) tear and the molars crush and chew.
 * Their proper function requires proper alignment, and a system where new teeth just come out whenever an old one is lost has been replaced by one of the proper characters of mammals; the one-time replacement of milk teeth by adult teeth in an orderly fashion. Of course there are variations that have developed on this theme, but it was the primitive condition of the first mammals, and still continues in most mammalian groups. μηδείς (talk) 23:47, 24 January 2017 (UTC)


 * I was going to suggest elephant as being monophyodont, but our article is a little ambiguous. They are specifically called polyphyodont, but the teeth aren't replaced vertically (as with humans) and that, when the last tooth appears, the animal must make them last - once they're gone, the animal starves. This is pretty clearly not what is usually meant by the description given in polyphyodont that the teeth are 'continuously replaced'. In elephants, they gradually edge forward as they wear down until the last teeth finally are useless and starvation occurs (if nothing otherwise kills them first). Matt Deres (talk) 18:06, 25 January 2017 (UTC)

Have you seen someone at the age of 90 grow teeth in his mouth again
--Akbarmohammadzade (talk) 04:26, 24 January 2017 (UTC) what is old age growing tooth ? — Preceding unsigned comment added by Akbarmohammadzade (talk • contribs) 06:44, 24 January 2017 (UTC)


 * Many years ago, there was a buzz on the Internet about a Russian woman who grew a tooth again long after she had lost all her teeth. Then, it turned out to be squamous cell carcinoma. That news wasn't as popular, so I figure anyone who read the first story still remembers the old Russian lady who regrew her teeth (though she only grew one "tooth"). 209.149.113.5 (talk) 13:05, 24 January 2017 (UTC)


 * The condition of growing extra, or "supernumary", teeth, is called Hyperdontia. -- Jayron 32 14:04, 24 January 2017 (UTC)

my patent
I hear some old man or woman regrow tine and little rows of teeth in their mouth .(MOHAMMADZADE)--Akbarmohammadzade (talk) 10:43, 26 January 2017 (UTC)

my mother has seen such man.His teeth have been like dental of sheep.--217.219.154.2 (talk) 10:36, 26 January 2017 (UTC)

(MOHAMMADZADE):in my mind is an invention that we use this fact for natural improvement of our tooth .how we can make our body to regrow new row of dental after losing them at same age of our life. it will be my patent.--Akbarmohammadzade (talk) 10:43, 26 January 2017 (UTC)


 * If we tell you how to do it here, any patent will probably be invalid. Graeme Bartlett (talk) 13:12, 26 January 2017 (UTC)


 * so ok--Akbarmohammadzade (talk) 16:23, 26 January 2017 (UTC)

As in movies
In movies, the person is shown to be made again just by a thread of hair. And, the memories are shown to be implanted. Is it even possible to implant the memories? And, how possible is the new clone be the same age from whom the clones were prepared? Are those things theoretically possible ? Learnerktm 07:39, 24 January 2017 (UTC)
 * Not such which movie this refers to, though it could be The Fifth Element.
 * The genetic "code" is stored in a DNA molecule that is (mostly) the same in all cells for a given organism, including hair follicles, so it is theoretically possible to make a clone from a single follicule (though not from the external hair part). Technically, of course, that is another story; you would need to have a full genome sequencing technique that works with a single cell, and then still generate an zygote with the matching genome, both of which are as far as I remember not feasible today. As for the new clone being the same age, well, if you wait enough time...
 * Notice however that DNA is not the full source code, and the individual's development is affected by the environment, so the end result should be "close enough", not "fully indistinguishable".
 * I will leave the memory question to someone else, but you can start at encoding (memory). Tigraan Click here to contact me 09:13, 24 January 2017 (UTC)
 * You wouldn't need full sequencing. You could extract the follicle cells, turn them into iPS cells (this is actually done in the building I work in), and theoretically form a clone out of those. The last bit is very theoretical in humans. (BTW, single cell sequencing is very much possible). And no, you can't implant memories, as we basically still know very little about how they work. Fgf10 (talk)
 * Cloning an individual is certainly possible (the main barriers are political/ethical/etc.), but bear in mind identical twins are clones. They have some similarities but many differences.  To transfer memory, you really have to lay on some industrial strength pseudo-science, preferably making up something original as you go along.  Perhaps the memory is somehow "transferred to the morphogenetic field" and begins to flow back again, or identical twins have a kind of telepathy that occasionally occurs, and in people without twins the excreted thoughts float around in the ether for years before winging back to the new clone.  Or there are billions of tiny, impossibly advanced aliens embedded in every pebble and drop of snot that make a secret high-resolution data store that they mistakenly put back into the clone.  I dunno, think of something.  But it's not going to be anything remotely plausible for ordinary people in a world where one lousy stroke reduces a loved one to living dead status for years on end. Wnt (talk) 14:02, 24 January 2017 (UTC)
 * An important article about what information is missing when you clone is epigenetics. Vespine (talk) 23:39, 24 January 2017 (UTC)
 * (I just realized Tigraan already linked to that article). Vespine (talk) 23:41, 24 January 2017 (UTC)
 * See Genetic_memory_ (aka "racial memory") for the idea that memories (or at least some memories) are inherited. Short answer: modern science considers this to be (mostly) bunk, although it seems that aversion to certain substances, traumas, etc may be inheritable.  (Presumably through some sort of epigenetics, but the article doesn't actually mention that). Iapetus (talk) 17:07, 25 January 2017 (UTC)

Octane rating: why are combustion kinetics faster for linear molecules?
I know that branched and cyclic hydrocarbons almost always have a higher octane rating than straight-chain ones, but what exactly is the mechanism which determines this? Does this have something to do with Markovnikov's rule and the relative energies for the formation of free radicals, i.e. that during ignition, the molecules break up more gradually and/or in a more predictable manner? 2601:646:8E01:7E0B:80A2:2428:A67E:94FC (talk) 11:47, 24 January 2017 (UTC)
 * Combustion chemistry is complex. The octane rating is not even a physical property, but an empirical measurement.  But I think that you're on the right track looking at radical mechanisms.  Certainly radicals have a key role in combustion: tetraethyllead served essentially to place lead atoms into the reaction, which would interact with the free radicals.  Since a free radical with a branch point is expected to be more stable than one that does not, that may matter.  But the length of straight chains also matters greatly even when there is no variation in how many carbons each carbon bonds to - compare the -130 for hexadecane to the 112 for propane!  And any branched structure inevitably shortens the straight chain and reduces the size of the molecule compared to others with a similar number of carbons. Wnt (talk) 14:34, 24 January 2017 (UTC)
 * Autoignition temperature is probably one of the relevant parameters, an article that is sparse on the chemical/structural causes but does mention chain-branching as being a consideration. And that aricle does go into some mathematical detail about the timing (using parameters of thermal conductivity, density, and specific heat capacity), which is clearly important in the octane-rating idea. DMacks (talk) 15:17, 24 January 2017 (UTC)
 * , some of the chemistry is covered by Combustion. Should that section be offloaded to Combustion chemistry or should that redlink redirect to that section so at least the link turns blue? DMacks (talk) 15:24, 24 January 2017 (UTC)
 * That's a tolerable redirect for now. I don't want to put the mechanism of combustion under combustion chemistry, because I think properly the latter term refers to the field of study rather than the process itself.  I'm sure there must be many academic departments and private corporate institutes which deserve to be mentioned in such an article, for example, though I know truly very little about it. Wnt (talk) 16:57, 24 January 2017 (UTC)


 * I took the liberty to change the title, in the hope it will attract a chemist's eye more easily. (I feel it must be true, there must be a topological/access reason, but that ain't a proof.) I suspect our OP is already somewhat familiar with the definition of octane rating, but just in case...
 * Octane rating basically is a measure of the autoignition delay (I should write a stub here someday...). In a gasoline, spark-ignited engine, you basically want the fuel-air mixture to burn with a nice premixed flame whose kernel starts when you trigger the spark. In practice, the compression stroke must bring you above the flash point even at cold start (otherwise the mixture won't burn and the engine won't start, which is a big no-no); but when the engine has been operating for a while, chamber walls are hot and the auto-ignition delays of the air-fuel mixture near the walls are dangerously low. If a pocket of air-fuel mixture spontaneously combusts, engine knocking occurs. One solution to avoid knock is to use higher-octane, i.e. less-reactive, fuel.
 * Funnily enough, that is the reverse for a Diesel engine: you want the fuel to vaporize and burn as soon as possible when you inject it, because it makes for a smoother combustion. Thus the cetane rating, which is basically a reverse octane rating. Tigraan Click here to contact me 18:57, 25 January 2017 (UTC)
 * is autoignition delay different than the idea covered in Autoignition temperature? DMacks (talk) 21:16, 28 January 2017 (UTC)

Ratings for lamp shades based on heat or light output?
I keep seeing |lamp shades with ratings on for the lights used in power/watts but they give different ratings for incandescents and energy-saving forms which to me makes no sense. If the lamp shade can handle 42 watts of halogen, why not 42 watts of any other bulb type? — Preceding unsigned comment added by 129.215.47.59 (talk) 15:30, 24 January 2017 (UTC)
 * This article is about lamp shade design, and shows recommendations based on Underwriters Laboratory standards; it appears the standards are based on incandescent bulb wattage, and designed to account for ventilation and heat output. I have no idea if similar standards have been developed for wattage of other bulb types (CFL, LED, etc.) but I would not expect the heat/wattage relationship to be the same given different types of bulbs.  That is a CFL which actually draws 60 watts may not have the same heat properties as an incandescent bulb would.  -- Jayron 32 15:53, 24 January 2017 (UTC)
 * [Edit Conflict] Because the important factor here is the heat the bulb puts out (which may cause the light shade or the fitting to catch fire if the shade's rating is exceeded). For example, traditional incandescent bulbs put out the majority of their rated power as heat (typically 95–98%); the various energy-saving types of bulb put out much less of their output as heat – which is why they're energy saving; most of their energy is being output as visible light, so they actually consume much less power for the same level of illumination. For example, a rather dated 20W compact fluorescent bulb is claimed on the packaging (which I still have to hand) to put out the same light as an 85W incandescent (were such a thing to exist).
 * Different types of 'bulb' give different proportions of their total power output as heat – LEDs, for example, give off almost no heat – so it's important to pay regard to the ratings to avoid putting too much heat into the shade, and as explained. {The poster formerly known as 87.81.230.195} 94.12.94.189 (talk) 16:01, 24 January 2017 (UTC)
 * ec The wattage of the bulb is the total amount of energy it consumes, energy that is converted into light and heat. Different types of lighting have different relative levels of light vs heat produced--"efficiency" talks about how much energy is wasted as heat in the process of creating a certain amount of light. A major difference among incadescent to CFL to LED is the increase in efficiency, meaning it takes a lower wattage bulb to produce the same amount of light, and therefore less heat is produced. Or the same wattage produces more light and less heat. I have no idea what criteria are used to establish the ratings on this item, but "total energy" only relates to the wiring, not the effects of the different fates of that energy. DMacks (talk) 16:03, 24 January 2017 (UTC)
 * The specific example is (a) "42W Eco Halogen" vs (b) "12W Low Energy". Both are equivalent lighting (42W eco halogen and 12W low energy/CFL are both 60W incandescent). So the rating is actually a limit on brightness? The halogen uses more energy to get the same brightness, which means more heat produced. If the design limit were about heat, I should be able to put an even higher wattage bulb in if it's of a more efficient bulb-type. DMacks (talk) 16:14, 24 January 2017 (UTC)
 * It was common to limit the wattage to 60 watts for incandescent bulbs in such fittings for heat reasons. I've often seen heat damage to fittings as a result of ignoring the limit.  Are the manufacturers just confused?  I can see no reason to limit the brightness.    D b f i r s   19:37, 24 January 2017 (UTC)

Food waste and rat traps
Given that every restaurant and supermarket will generate some food waste and that rats are ubiquitous in cities, why don't humans look for free food in dumpsters, thereby competing with the rats and seagulls and other urban creatures for food that costs time and energy instead of coins and paper? Why must the food be shipped from a factory or a farm and transacted in grocery stores? Why can't humans just eat what they can find locally? Other animals spend their entire days searching for food. Humans have to work 8 hours a day (full-time) or less than that (part-time), and 8 hours may be spent on sleeping, so the remaining 8 hours may be spent on searching for food in dumpsters and setting up rat traps or teaching other humans how to search for food to minimize food wastage. If a seagull ingests toxins, then the human that eats the seagull ingests toxins as well. The toxins will limit human population growth, so in order to expand the human species, humans will have to learn how to minimize the presence of toxins in the environment. 66.213.29.17 (talk) 16:09, 24 January 2017 (UTC)
 * You first. And humans do look for free food in dumpsters. --jpgordon&#x1d122;&#x1d106; &#x1D110;&#x1d107; 16:15, 24 January 2017 (UTC)


 * Don't know what planet your living on but many folks have had to resort to Freeganism & Dumpster diving for many years in order to to survive and not let their children starve to the point that they are taken away by the social services. Many people fall through the cracks of social welfare and so are all ready competing with rodents.--Aspro (talk) 16:27, 24 January 2017 (UTC)
 * I didn't know there was an article on Freeganism! Though, I didn't know that was an actual concept. 66.213.29.17 (talk) 16:48, 24 January 2017 (UTC)
 * I think this suggestion is too stupid to warrant further discussion. 129.215.47.59 (talk) 16:29, 24 January 2017 (UTC)


 * That is your opinion. This modern developed World is the richest in all recorded history but hunger has not gone away and is getting worse. Just be thankful that you have never experienced what prolonged hunger really feels like! Remember, haggis was hailed because it gave subsidence at the time of the year when animal protein was in very short supply... and it was so cheap that even Scottish peasants could afford it, as it was made from the discarded offal.--Aspro (talk) 16:40, 24 January 2017 (UTC)


 * Obviously it's my opinion. The OP suggested that people voluntarily eat foot with toxins as an alternative to purchasing food of an appropriate quality in a supermarket. They suggested that people voluntarily off themselves by scavanaging and foraging and hunting pigeons when they're not busy at work. It's moronic but I'm not sure there's any objective way to frame that. But go ahead and waste your time on what looks like a troll post. — Preceding unsigned comment added by 78.148.97.148 (talk) 20:13, 24 January 2017 (UTC)


 * Lobster is interesting. Never know what will become popular. DMacks (talk) 16:51, 24 January 2017 (UTC)


 * The potential for disease seems obvious. Scavengers are typically specialized for the purpose.  That said, the "omnivorous" human is quite a mystery to me.  I've been told Homo erectus gained an endurance runner's physique doing marathons following the vultures above old lion and hyena kills with bones to crack for their marrow.  But people do not do so well eating rotten food as to seem like plausible scavengers; their primate stomachs and lack of vitamin C biosynthesis for example are in line with fruit eaters.  Though humans can be carnivorous, they are not true carnivores either in that they don't (usually) eat feces; they hack off just certain bits they like.  I am inclined just to take the approximation that humans don't properly scavenge because they're not scavengers. Wnt (talk) 17:04, 24 January 2017 (UTC)
 * By coincidence, just 2 days ago I went to put a bag of garbage into a skip (dumpster). The one I usually use was locked, so I went to the next one which is owned by the nearby supermarket.  There, sitting on the top were 2 salmon fillets in totally perfectly sealed packaging.  So, what do I do? Yes, I took them.  The fillets were dumped because they were on the last day of their "sell by" date.  I was thinking more that animals had been reared and died to provide this food...what an immoral act to throw them out simply for commercial reasons. DrChrissy (talk) 20:38, 24 January 2017 (UTC)


 * Uhm. This has lead me to double-check my eating habits for when my nose is in the pigs trough. I have been happily assuming that the toxins produced by bacteria feasting on fish and meat are heat liable to the point that adequate cooking destroys them, even when the Food H&H would declare the product as putrid. Fish sauce is derived from purified fish, and there are constant reports that the African community of  the UK smuggling in putrid 'bush meat' etc. Whereas, the toxins associated with cereals, cooking does not destroy them, as is well known by the take-away Chinese restaurant syndrome. Mouldy cheese is another problem as the toxins permeates invisibly though the cheese.  Not so much asking for medical advice as tips for expanding my Dumpster Gastronomy. Also, around skips here in the UK there are often foxes and providing one takes care on dealing with the scent gland during butchering and marinate them in vinegar for a couple of days, one can avoid the meat having a foxy taste (for a condiment -one can't go wrong with a bit of grated horseradish). --Aspro (talk) 22:41, 25 January 2017 (UTC)


 * The problem appears to be that people who raid supermarkets' bins get prosecuted for theft.  It's not clear what happens if a bin is owned by a supermarket but placed on public land (see above comment).   Probably nothing, since many bins for public use are serviced by private contractors.   The growth of food banks has gone some way to make life more tolerable for the poor.   However, a third of food goes to waste and something is being done about that..92.2.72.206 (talk) 13:03, 25 January 2017 (UTC)
 * Where do people get arrested for stealing from a dumpster? Here in the good ol' US of A, trash is owned by no one, and cannot, legally speaking, be stolen. However, you could still get in trouble if you have to trespass to reach the trash. Someguy1221 (talk) 13:07, 25 January 2017 (UTC)
 * That's the whole point.  See Dumpster diving. 92.2.72.206 (talk) 13:21, 25 January 2017 (UTC)


 * Supermarkets in France, and almost so in the UK, are now seeing government pressure to address this, by organising re-use schemes for this surplus food. It's a good move.
 * As to the legal ownership of rubbish, then I'd be surprised at any Western country where "trash is owned by no one". This is either very clearly owned (the UK position) and dumpster diving is illegal, although rarely prosecuted, or in more forward looking countries like the Netherlands and Germany there is a formalised arrangement for what's offered for free collection and use. Andy Dingley (talk) 13:28, 25 January 2017 (UTC)
 * In the U.S. trash is unowned, and the dumpsters public, in the sense that police feel free to rummage through it looking for evidence. But giving food to the homeless is viewed as inherently evil so I wouldn't make any promises for private citizens going unprosecuted, even with their own private food on private land, let alone any situation where someone can choose a different interpretation.  But this isn't science... Wnt (talk) 00:47, 26 January 2017 (UTC)


 * ? Monsanto spent years deigning they owned their waste. --Aspro (talk) 22:52, 25 January 2017 (UTC)
 * Denying? —Tamfang (talk) 07:18, 26 January 2017 (UTC)

material science
if a unit cell of a tin has a tetralgonal symentry with a and c lattice parameters 0.318nm and 0.583nm respectively, if it density, atomic wieght and radius are 7.30g/cm, 118g/mol and 0.15nm respectively. What is its atomic packing factor. — Preceding unsigned comment added by Abdul Sal (talk • contribs) 16:29, 24 January 2017 (UTC)
 * Its atomic packing factor is...a good homework question indeed!


 * DMacks (talk) 16:34, 24 January 2017 (UTC)

Genetic modification
If an apple is genetically modified to contain caffeine or some kind of drug from another plant, then would it get a food label or a drug label? How would doctors prescribe such a medicine? Can pharmaceutical companies own large industrial farms with genetically modified apples, eggplants, squashes, romaine lettuce heads, etc.? 66.213.29.17 (talk) 17:21, 24 January 2017 (UTC)
 * Here is an article that discusses some of the issues surrounding the use of genetically modified organisms and drugs. Here is perhaps a more neutral source that discusses the legality.  One thing to note: regulation has always lagged behind technology.  That is, governments don't create laws in anticipation of a concept maybe existing sometime in the future.  Governments only create regulation to deal with problems as they come up.  Since there currently is no genetically modified apple that has caffeine, there exists no law that deals with the way such a thing is to be labeled, and who is responsible for regulating such a thing.  Unless and until caffeinated apples exist, your question will continue to be unanswerable.  -- Jayron 32 17:28, 24 January 2017 (UTC)
 * That said, I doubt there is tremendous interest in genetically engineering drug containing apples. Apples require large areas of land, nutrients, water, etc., to successfully grow. It's the only way to get an apple, but it isn't the only way to get most drug compounds. If drug compounds are made from genetic engineering at all, bacteria are usually used. They make excellent chemical factories and are used in bioreactors, where much more efficient use of input materials is made to get the desired product. Insulin is made in e. Coli bioreactors, for example. --OuroborosCobra (talk) 19:49, 24 January 2017 (UTC)
 * Also yeast   .  That said as the first article mentions, there is a reasonable amount of research into using plants as biofactories (also plant and animal cell culture and animals). However these are normally with other plants, particularly tobacco and the intention is generally to produce the product which can then be extracted and purified in some way. We do have a not very good article Plant manufactured pharmaceuticals and a slightly better Pharming (genetics) (these probably should be merged). Note that these are still mostly in the research stage. This  from 2015 claims the only approved (I suspect this means FDA approved) drug produced in this fashion is Taliglucerase alfa. Note that this was a few years after ATryn produced in goats (milk).  There have been suggestions of the pharmaceuticals (including vaccines) actually being in edible parts of plants, although still not generally apples AFAIK, but these are generally more blue sky ideas. And what research there is has often hits the obvious problems like controlling dosage   . So most likely if it does happen, in the short term at least, it will be with some processing to produce a controlled dose. Or alternatively it may be used e.g. for vaccinating farm animals where there may be less concern over over- or under- dosing.  Nil Einne (talk) 06:21, 25 January 2017 (UTC)
 * I noticed something interesting that I missed in my first skim through the first source, it suggests from 2005-2009 mammalian cell culture was the most common production method for approved biopharmaceuticals. (Remember of course this is only the number of approvals, not how much those products are used.) It gives 3% for transgenic animals or plants. Given the numbers 10 in 2005, 13 in 2006, 15 in 2007, 10 in 2008, 20 in 2009 totaling 68 over the period, this may seem to imply 2. But I think this is because ATryn was counted twice, once for the EU (in 2006) and once for the US (in 2009). This would apply to a number, but not all of the biopharmaceuticals they were considering. (I.E. If you only count them once, the percentage will likely vary, although mammalian cell dominates enough I'm pretty sure it still will in that period.) Nil Einne (talk) 06:44, 25 January 2017 (UTC)
 * BTW, it looks to me like Chinese hamster ovary cell was the predominant mammalian cell culture in that period. Nil Einne (talk) 10:27, 25 January 2017 (UTC)

Does the SI need 7 basic units?
Besides the glitch of the kg (which is not defined in natural units), couldn't the SI be simplified? Couldn't we define it in less than the 7 SI base units - second, metre, kilogram, ampere, kelvin, mole, and candela? The meter for example, is just a fraction of the distance that light travels in 1 second, therefore, not fundamental, but derived. Or, are they trying to define all units based in concepts that are common knowledge? Hofhof (talk) 18:17, 24 January 2017 (UTC)
 * The base SI units are based upon basic measurements. The fundamental set of base measurements is somewhat arbitrary, but at some point you need to have certain measurements pegged to universal standards, such measurements then are irreducible to other measurements.  You need to measure distance, time, number and mass, and also have some fundamental measurement of electricity, heat, and light.  The first four are more "fundamental" in a sense, since distance doesn't give you a lot of choices: the space between two points is the space between two points, and not much else to measure there.  The number of objects in a set is a countable thing, and you pick some number (Avogadro's number in this case) as the defined counting set.  So those measurements are pretty much locked in.  For measurements of electricity, heat, and light, there's some leeway how you define the fundamental measurements.  For example, is electric charge more fundamental or is electric current more fundamental?  Arguments could be made either way, and it doesn't matter much since you can define one in terms of the other and time (thus current = charge divided by time, OR charge = current times time).  For various reasons, it was decided "current" would be chosen as the base measurement, and then charge was pegged to that.  The same with heat measurements for example: do we go with energy or temperature, knowing the two are tied together by the Boltzmann constant?  It was decided to go with Temperature instead.  Once you've defined your basic set of measurements, then you pick a unit that is most convenient for the work you are doing.  For most human-sized things, meter, kilograms, seconds, moles, amperes, kelvin, candela, etc. all work well because for most people, it gives them nice 1-3 digit numbers to work with.  People's number sense tends to break down for very large or very small numbers, so the units chosen allow numbers that we can wrap our heads around.  -- Jayron 32 18:28, 24 January 2017 (UTC)
 * Convenience is why inches, feet, yards, etc. still work well. ←Baseball Bugs What's up, Doc? carrots→ 23:40, 24 January 2017 (UTC)
 * Precision: only the people that were educated in these units find them convenient. It is an argument to stay with the system you have, not to prefer imperial to metric. (It is not a bad argument though.)  Tigraan Click here to contact me 13:15, 25 January 2017 (UTC)
 * Inches, feet and yards are "people-friendly" units. ←Baseball Bugs What's up, Doc? carrots→ 15:23, 25 January 2017 (UTC)
 * As are centimeters and meters. -- Jayron 32 15:39, 25 January 2017 (UTC)
 * Centimeters are too small, while meters are too large (by 3.37 inches). If you're trying to estimate the size of something and have no measuring instrument, your foot will have to do - and there's no foot in the metric system. Powers of 10 are fine for science, but not so good for normal human activities. ←Baseball Bugs What's up, Doc? carrots→ 16:18, 25 January 2017 (UTC)
 * Surely that is totally dependent on what you are measuring. Metres are not too large for measuring road distances or the distance to the moon. DrChrissy (talk) 16:23, 25 January 2017 (UTC)
 * Yes, it's good for science. Most of us are in no position to be stepping off the distance to the moon. ←Baseball Bugs What's up, Doc? carrots→ 16:37, 25 January 2017 (UTC)
 * Centimeters are not substantially different from inches, nor meters from feet/yards to be inconvenient. Any item whose measurement is expressed in inches will be within one order of magnitude as one whose measurement is in centimeters.  Similarly any item whose size is expressed in meters will be within one order of magnitude as one whose measurement is in feet.  There's no other way to quantify convenience except "what kind of numbers do I need to express this quantity", and humans have a natural number sense for 1-3 digit numbers.  A person who is approximately 6 feet tall is approximately 2 meters tall; those are of the same scale (and thus convenience).  An object that is about 30 centimeters long is about 12 inches long, those are both convenient 2 digit numbers.  On any quantifiable measure of convenience, regarding human's ability to process and deal with numbers, the systems are perfectly equivalent, and thus neither is "better" if that was the only justification for keeping one over the other.  -- Jayron 32</b> 16:38, 25 January 2017 (UTC)
 * E/C Exactly. Convenience is a matter of what we have learned (not even as children) and the context.  Try telling a horse owner their dobbin is 2.2 m high at the withers.  They will likely stare with incredulity and ask "how high is that in hands? DrChrissy (talk) 16:48, 25 January 2017 (UTC)
 * I'm not so sure the average human is all that keen on decimal fractions, except maybe when it involves dollars and cents. Like if someone is 6 foot 3 inches, saying he's 6.25 feet sounds a bit effected. ←Baseball Bugs What's up, Doc? carrots→ 16:43, 25 January 2017 (UTC)
 * And yet, you can buy your lunch with $5.37 just fine, instead of -/2/6 -- Jayron <b style="color:#090">32</b> 17:11, 25 January 2017 (UTC)
 * I doubt that even applies to the US or UK, and it definitely doesn't apply to most of the world with a decent education system. When I buy a 1.5kg bag of sugar, I can trivially convert it to g and so easily know the difference between a 400g bag (or whatever). Ditto with length, volume etc. I don't have to waste time converting ounces into pounds etc. And yes, there's nothing weird about saying my height is 1.65m. Or I can say it's 165cm. Again, I don't have to stupidly waste time converting between feet and inches. And the difference between my height and someone who is 2.2m is a fairly trivial calculation. By comparison comparing the height of someone who is 6 feet 3 inches and someone who is 4 feet 9 inches is more involved. If your education system doesn't prepare you to easily understand decimal fractions, there's something seriously wrong with your education system. Maybe that's why you have crap like this . Nil Einne (talk) 14:45, 26 January 2017 (UTC)
 * It actually took me twice as long to calculate the difference in heights in metric, but then I was brought up on feet and inches (less than 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom in both cases)  Whatever you are most familiar with will seem better to you.    D b f i r s   16:22, 26 January 2017 (UTC)


 * If you're trying to estimate the size of something and have no measuring instrument, your foot will have to do - well, I can affirm without even looking at the internet that the variation of foot size between adult humans is at least ±20%, let alone among children. Unless you regularly calibrate your foot to know the conversion factor with the Standard Foot (the king's?), and then you still have a factor to deal with, that is not a good argument.
 * What really happens is that you have a general idea of how much "a foot" is in your memory. Not a perfect one, of course, but something that is correct at ±10% is still better than actually using your foot. But of course, everyone with age>15 in say France has such a general idea for "meter", "kilogram" and so on.
 * By the way, if ever you need to measure a length somewhere in the 20-100cm range with reasonable precision without a ruler, A4 paper is your friend. A combination of short edges, long edges and folding in two gets really handy. Tigraan <span title="Send me a silicium letter!" style="color:">Click here to contact me 19:13, 25 January 2017 (UTC)
 * ...do we go with energy or temperature, knowing the two are tied together by the Boltzmann constant? - I am not sure what you meant here. Energy is already defined as a combination of mass-time-length. To define the temperature scale, you can use an energy formulation (e.g. fixing the value of the Boltzmann constant, or the heat capacity of a given element), or e.g. an entropy formulation (see Temperature); but in the end, you always need some value that involves temperature-like units. Tigraan <span title="Send me a silicium letter!" style="color:">Click here to contact me 13:15, 25 January 2017 (UTC)
 * Yes, that is more correct; ultimately Temperature needs a definition of its own because it is NOT reducible to mass-time-length the way energy is. With electricity, either charge or current needs to be defined for a similar reason.  Thanks for fixing my inaccuracies.  -- Jayron <b style="color:#090">32</b> 13:39, 25 January 2017 (UTC)
 * Yes, it is quite possible. CGS uses just three. Ruslik_ Zero 20:46, 24 January 2017 (UTC)
 * Centimetre–gram–second_system_of_units shows how it works. Even though there are "only three units", some physical constants have been set to 1 to kill the units that are not there.
 * Strictly speaking, you do not need any units. For instance, the metric system says "the second is defined by: 9 192 631 770 x (the cesium hyperfine transition duration) = 1s". The Tigraan-0-unit sytem says "(the cesium hyperfine transition duration) = 1/(9 192 631 770)". Yay, I have "one less unit"!
 * The thing is, having units is good because it can prevent errors. I think the candela and maybe the mole should be dropped from the SI base definitions with that trick, because neither is based on a reasonably fundamental physical value, but I would still use them in calculations. Tigraan <span title="Send me a silicium letter!" style="color:">Click here to contact me 13:34, 25 January 2017 (UTC)
 * The thing is, even if the unit were dropped, the measurement is still required. With the mole, for example, we still need a measurement of number; even if it is just the "single" rather than the "mole"; the single would make the unit system simpler; but it would make the numbers messy.  (People get tired of writing x 10^23 over and over).  The same thing with the candela; illumination is not reducible to the other units; like electricity you have a choice of measurements to use (for example Luminous intensity or Luminous flux) -- Jayron <b style="color:#090">32</b> 13:45, 25 January 2017 (UTC)


 * Side note: if the kilogram is a glitch because it is not defined in natural units, surely the candela is a glitch as well. It is not really more natural (why take humans as a reference? and which humans, those of today or the average Homo erectus?), and it is much less precise. The internet did not give me a firm estimate for the precision of manufacturing of the IPK, but it seems to be somewhat lower than 1 ppm (1mg/1kg). Because of the tons of genetics that affect human vision (see e.g. ) I would already be impressed if between two typical humans the perception of "one candela" was within 1‰. Tigraan <span title="Send me a silicium letter!" style="color:">Click here to contact me 13:48, 25 January 2017 (UTC)
 * FYI, the definition of the kilogram is changing soon to be defined by a universal constant. See Proposed redefinition of SI base units.  -- Jayron <b style="color:#090">32</b> 14:17, 25 January 2017 (UTC)
 * I knew. The French press was full of tearful "our poor IPK has been cast aside" in the science pages last year, and I am nerdy enough to read those. Tigraan <span title="Send me a silicium letter!" style="color:">Click here to contact me 14:26, 25 January 2017 (UTC)
 * I mean kg is a glitch, because it's not based on a measurement from a natural phenomenon. If someone in China decided to rebuild calculate everything from scratch, he would have to get access to that weight in France.Hofhof (talk) 17:51, 25 January 2017 (UTC)
 * Fair enough. IIRC the decision was to favor reproducibility over availability, because (maybe surprisingly) options such as "the mass of a given volume of water" failed for a long because the measurement precision on mass was much better than the control of impurities that made impossible to obtain the same result twice. Tigraan <span title="Send me a silicium letter!" style="color:">Click here to contact me 19:21, 25 January 2017 (UTC)
 * I have a distaste for the ampere in favor of the faraday (unit); essentially, replace coulombs with "moles of charge" per Faraday constant. But I have to admit that constant isn't perfectly known, the units require a few perhaps inelegant uses of prefixes, and even "one unit charge" is still technically a unit, even if an obvious one, and like all obvious things you also have to decide which obvious, since there's the fine structure constant to leave in or out. Wnt (talk) 15:54, 25 January 2017 (UTC)


 * Side note: the most inconvenient aspects of measurement seems to me to have two systems for different activities. Hofhof (talk) 17:59, 25 January 2017 (UTC)


 * You can get rid of the base units by fixing the numerical value of physical constants. Instead, these physical constants are defined as ratios between our base units. (This can even be made true for the kilogram. Look at Proposed redefinition of SI base units.) But you are just shifting the problem. You still need to arbitrarily fix seven numerical constants somehow. For example, we could arbitrarily define seven particular physical constants to have the numerical value of "1". Then all other units would be derived. Instead, we choose to define our base those physical constants in terms of the "base units" we began using in 1795, in order to make it easier to continue to use all of the science and engineering that we have done since then. -Arch dude (talk) 19:01, 25 January 2017 (UTC)
 * Assuming that is a desirable outcome for usability. As noted above, measurement systems exist as they do for usefulness, not just some arbitrary definition of elegance.  Having numbers be usable by people by tapping into their innate number sense is very desirable.  -- Jayron <b style="color:#090">32</b> 00:41, 26 January 2017 (UTC)

Animals making knots
I just added Knot and am wondering if other animals make and use knots. Birds? Primates? Anna Frodesiak (talk) 22:33, 24 January 2017 (UTC)
 * Hi Anna - some of the most wonderful knots are produced by weaver birds.


 * But is a weave a knot? We've not figured that out yet. Anna Frodesiak (talk) 22:41, 24 January 2017 (UTC)
 * I asked myself the same question before I posted here. So, I checked our Knot article which states "A knot is a method of fastening or securing linear material such as rope by tying or interweaving."  So there we have it - WP is never wrong (hee hee)! DrChrissy (talk) 23:10, 24 January 2017 (UTC)
 * Having thought about this a little more, if we accept the "looser" definition of knots as including inter-weaving, many bird nests could be included as having knots and many other animal nests such as drays of squirrels and nests of primates (they interweave leaves together) could be included. Perhaps I am getting myself into knots about this! DrChrissy (talk) 23:20, 24 January 2017 (UTC)
 * FWIW, I've studied mathematical knot theory, as well as various forms of knots used by surgeons, sailors, anglers, rescue workers, rock climbers, and the assorted rag-tag enthusiasts over at the international guild of knot tyers. And none of them consider weaving (in the sense of a woven basket or nest) to be a knot. If we do the obvious end-identification of each strand used in a weaver bird nest, then the nest would be a link_(mathematics) (called so by analogy to a chain being linked unknots). We have braid and plait and tangle and all sorts of knot-adjacent words, but I'd recommend including the weaver birds with obvious caveats, maybe something like "Though not necessarily a "knot", birds weave a basket nest (ref)". SemanticMantis (talk) 23:19, 25 January 2017 (UTC)


 * Orangutan - http://www.livescience.com/54780-orangutan-wattana-is-knot-tying-master.html Wymspen (talk) 23:30, 24 January 2017 (UTC)
 * That is a great video - thanks for that! I have a word of caution though. The authors state that they never taught the orang to tie knots.  This might be true, but that does not mean she did not learn by Observational learning.  However, the video clearly shows her tying knots! DrChrissy (talk) 23:47, 24 January 2017 (UTC)
 * Most orangs do learn to tie knots either by observational learning or by being taught AFAIK. Scouts etc are a common place for orangs to learn to tie complex knots, at least in the developed world. Nil Einne (talk) 02:25, 25 January 2017 (UTC)
 * If you ever say anything like "etymological fallacy", I'm gonna mention this. —Tamfang (talk) 07:33, 26 January 2017 (UTC)


 * As I recall, no child learns to tie knots by having the theory explained to them. They watch, and copy. Most practical skills are acquired by observational learning, and it makes little difference whether the demonstration is deliberate or unintended. Now, the real test would be if an orangutan was given a tied knot, and two bits of string, and worked out how to duplicate the knot without actually seeing someone tie one. Possible? I'm a frayed knot. Wymspen (talk) 09:59, 25 January 2017 (UTC)
 * I think the point is that it learned from a human, so that's not really an animal behavior. ApLundell (talk) 14:27, 25 January 2017 (UTC)
 * I would take issue with that statement on a couple of points. First, humans are animals.  Second, if the orang performs a behaviour, whether learned or not, by definition, it is an animal behaviour.  Perhaps you were trying to say the behaviour is not one which occurs in the ethogram of their naturally occurring behaviours. DrChrissy (talk) 16:06, 25 January 2017 (UTC)
 * I should point out again that your 2 points are actually the same point. Of course if you referred to orangutans rather than orangs, you may have distinct points. Nil Einne (talk) 01:18, 26 January 2017 (UTC)
 * Ahhh..... I think I see the confusion here. I have used the term "orang" in the way that many involved in animal science use it, i.e. as an abbreviation for "orangutan".  I suspect you might be using it more literally as a term for some humans, e.g. Orang Asli.  Apologies for my sloppy use of English. DrChrissy (talk) 09:55, 26 January 2017 (UTC)
 * To be clear, orang means people. It doesn't just refer to some people but to all people. You and I are both orangs. This is probably at least one of the reasons why from my experience, most (not all!) people who actually work with orangutans in animal science don't actually say orang when they mean orangutan no matter what languages they speak. Nil Einne (talk) 22:23, 26 January 2017 (UTC)
 * Hagfish make knots to pull scraps off dead bodies or escape being caught. Dmcq (talk) 23:52, 24 January 2017 (UTC)
 * Yes, they literally tie their bodies into a knot. They also do this in order to scrape slime off their bodies.  (The hagfish is sometimes known as the "slime eel" because of the copious amounts of slime they can secrete, as a defense mechanism.) Looie496 (talk) 15:15, 25 January 2017 (UTC)


 * Knot tying in great apes: etho-ethnology of an unusual tool behavior . They are very cautious, and stress that incontrovertible in situ evidence is minimal. However there are many, many accounts of all the great apes tying and untying knots, going back to Fossey. I'd personally think you could add "Evidence of knot tying has been gathered for chimps, orangatans and gorillas", giving this paper as reference. I've seen in many places a stronger claim that gorillas use the overhand knot specifically as part Nest-building_in_primates, see video here . At the moment I can't find a ref specifically supporting that claim, but it might help you find additional material (and of course our refs don't have to be to scholarly primary literature). Great question, thanks for improving the article! SemanticMantis (talk) 23:30, 25 January 2017 (UTC)