Wikipedia:Reference desk/Archives/Science/2013 February 25

= February 25 =

Pot stats in USA
Hello all, I'm trying to find a comparative breakdown of the marijuana abuse rate trends state-by-state from 1998 to present. Here are the requirements I have for this data: (1) it must be from a reputable source; (2) it must show the marijuana abuse rates separately for each of the 50 states; (3) it must show these rates over several years, preferably over the entire period from 1998 to present; and (optional but preferred) it wouldn't hurt if it indicates which of the states have legalized pot, and in what year. I've been trying to find it for days, but all the studies I've found either aggregate the data over the entire country, or else they only have the data for one year (two at the very most). Thanks in advance! 24.23.196.85 (talk) 00:44, 25 February 2013 (UTC)


 * Not that I have an answer in any case, but I think you need to specify what you mean by "abuse". Do you mean, say, (1) any recreational use, (2) recreational use in violation of state law, (3) usage that causes medical harm or makes it difficult for the user to discharge his ordinary responsibilities?  The most justifiable sense of the word "abuse" is number 3, but it's also a bit vaguely defined, so precise stats would depend on who is judging. --Trovatore (talk) 00:58, 25 February 2013 (UTC)


 * Because marijuana is largely illegal, it's almost impossible for precise figures on anything to do with its use to be collected. HiLo48 (talk) 01:15, 25 February 2013 (UTC)


 * Yes, that's true. Still, there is an extra layer of ambiguity added by the term abuse.  On the other hand, I suppose it's possible that there are avenues to track genuine abuse (sense 3 in my list) that are not available for private use that doesn't cause obvious harm.  For example, you could interview doctors and ask them to provide aggregate statistics, without identifying any individual. --Trovatore (talk) 01:20, 25 February 2013 (UTC)


 * I actually meant "abuse" in sense (1). 24.23.196.85 (talk) 01:28, 25 February 2013 (UTC)


 * Since that's not the normal use of the term "abuse", I suggest you use the term "recreational use", instead, when doing searches. StuRat (talk) 01:31, 25 February 2013 (UTC)


 * Anti-drug warriors are probably the only ones who use "abuse" in sense (1). ←Baseball Bugs What's up, Doc? carrots→ 06:14, 25 February 2013 (UTC)


 * or sense 4, insulting and belittling the substance until it feels bad about itself, or sense 5, physically injury to the substance Gzuckier (talk) 06:32, 25 February 2013 (UTC)
 * I remember a girl who would look for any opportunity to use the phrase "that's alcohol abuse!". Examples might be spilling beer or dropping a bottle of champagne. --Trovatore (talk) 08:19, 25 February 2013 (UTC)


 * To Mr. Bugs: Since when is there anything inherently wrong with being an anti-drug warrior? 24.23.196.85 (talk) 06:52, 25 February 2013 (UTC)


 * Ever since it became blatantly obvious to all rational people that the war on drugs was never going to reduce drug usage. HiLo48 (talk) 07:19, 25 February 2013 (UTC)
 * Well, that's not really all that logically connected &mdash; you could be a crusader in a hopeless cause and still be right. But the more pertinent question is, why should we consider all recreational use of marijuana to be "abuse"?  Is there any decent evidence that the people who so consider it are right?  --Trovatore (talk) 08:18, 25 February 2013 (UTC)
 * The key here is that we should avoid words that place a normative value on behavior. Instead, as most researchers do in areas such as this, we need use terms that themselves don't contain values; abuse implies a negative connotation, while a word like "use" does not.  "Use" is not debatable: either a person has or has not used marijuana.  Abuse, on the other hand, requires us to place values on which kinds of uses (if any) are allowable or not, and as such, words like that should be avoided.  -- Jayron  32  16:06, 25 February 2013 (UTC)
 * To HiLo48: There are plenty of rational people who support the War on Drugs (or in any case oppose legalization), so your implication that their views automatically make them irrational is a flat-out lie! Now get lost, you America-bashing pothead! 24.23.196.85 (talk) 01:22, 26 February 2013 (UTC)
 * "Rationality" means, at the minimum, being able to draw valid conclusions from given premises. While HiLo may or may not be an America-bashing pothead, your conclusion that he is doesn't follow from the evidence available, making your rant a good example of irrationality.  I also suggest that you read WP:CIVIL and WP:NPA before posting again, remembering that all of us are unpaid volunteers.  If you're not able to follow these policies, I think you're the one who should get lost.  --140.180.254.250 (talk) 01:48, 26 February 2013 (UTC)
 * It DOES follow from the derogatory statements about my country that he makes on his user page, AND from some of his previous comments! (Like, for example, the following: "I also find it necessary to protect Wikipedia against, again, mostly American editors who want to impose conservative, middle American Christian values here. Apparently Conservapedia isn't enough for them.")  And as an American patriot, I don't HAVE to be civil to America-haters like him!  So I say once again: HiLo48, fuck off! 24.23.196.85 (talk) 06:25, 26 February 2013 (UTC)
 * A rational person would realise that my comments are not criticism of a country. In fact, to criticise a whole country would be pretty weird. HiLo48 (talk) 06:32, 26 February 2013 (UTC)
 * And yet I remember you calling all Americans stupid a while back! 24.23.196.85 (talk) 00:02, 27 February 2013 (UTC)
 * Please point out where, in WP:CIVIL or WP:NPA, it says that "American patriots" are exempt from its proscriptions, or that "America-haters" are exempt from its protections. By editing Wikipedia, you agree to be bound by its policies.  I would also note that you are reinforcing common negative stereotypes about Americans, and as such, are hurting your patriotic cause more than HiLo ever could.  --140.180.254.250 (talk) 08:07, 26 February 2013 (UTC)


 * Nothing wrong with it, but I wouldn't look for unbiased statistics from anyone with a particular political agenda. I also wouldn't trust any figures from the participants in the Hash Bash.  If you want reliable stats, look for them from uninvolved scientists, who won't tend to use subjective terms like "abuse". StuRat (talk) 07:20, 25 February 2013 (UTC)
 * That's what I'm trying to do -- but the problem for me is not finding reputable and unbiased sources (I've already found quite a few on my own), it's finding sources that track pot abuse separately in each state instead of aggregating the data for the whole nation. What I need are comparative statistics among the different states, not just one rate for the whole country. 24.23.196.85 (talk) 01:29, 26 February 2013 (UTC)
 * Until you lose that politically-charged term "abuse", you're not likely to get a good answer here. ←Baseball Bugs What's up, Doc? carrots→ 08:42, 26 February 2013 (UTC)
 * And I still can't see how realistic statistics can be collected on the use of something illegal. HiLo48 (talk) 20:47, 26 February 2013 (UTC)
 * Indeed. The best data anyone is likely to get would be what are technically known as "guesstimates". ←Baseball Bugs What's up, Doc? carrots→ 22:27, 26 February 2013 (UTC)

Lithium ion batteries
Can electronics with lithium ion batteries be damaged if you don't use it enough or don't charge it fully before taking it off the charger? Clover345 (talk) 01:58, 25 February 2013 (UTC)
 * No, not if the battery is working correctly, but you can potentially shorten the life of the battery. Looie496 (talk) 02:57, 25 February 2013 (UTC)
 * How often does it need to be used or charged fully to prevent this? Clover345 (talk) 10:32, 25 February 2013 (UTC)


 * That's not right Looie. Removing a lithium ion batteries from the charger before it's fully charged doesn't shorten the life of the battery. In fact, the opposite is true. Charging the battery up to 100% shortens the life of the battery. Dauto (talk) 14:45, 25 February 2013 (UTC)

So which is it and why? Don't most electronic manufacturers recommend that you charge up to 100% at least once a month? Clover345 (talk) 16:38, 25 February 2013 (UTC)


 * Yes, Li-on cells behave differently from other rechargeables. They must never be deeply discharged, and the control circuitry normally protects against this by cutting off the power when the voltage falls to a minimum level.  For this reason, they can become unusable if left discharged for a very long period.  Other than this, it probably doesn't make much difference to the life if you charge from half-discharge or give a quick boost charge to less than full.    D b f i r s   16:42, 25 February 2013 (UTC)


 * I would guess that the reason is to ensure that the battery never becomes fully discharged. My camera battery has been left without charging for many months and still works perfectly and holds a good charge.    D b f i r s   16:44, 25 February 2013 (UTC)


 * ... later note: ... I'd forgotten about recalibrating the power gauge for discharge monitoring. (Failing to do this might give an apparent shortening of battery duration, but this will be corrected when next fully charged.)  See Guy's links below. Using Li-on cells without control circuitry is not to be recommended unless you really know what you are doing.   D b f i r s   08:21, 26 February 2013 (UTC)

I have designed several Lithium-Ion Battery chargers. I have prototyped several different approaches, but I always end up going back to using a subset of the Atmel ATAVRBC100 battery charge management reference design ( http://www.atmel.com/Images/doc8088.pdf http://www.atmel.com/images/doc8080.pdf ) using an Atmel ATtiny25 ( http://www.atmel.com/Images/doc2586.pdf ). As you can see from the datasheet, this is a smart charger design which allows the user to just connect the battery and walk away without worrying about overcharging or undercharging. In most cases (laptops, cellphones), there is another smart battery management circuit handling the discharge cycle, which allows the user to just let the device run until it stops working without worrying about overdischarging or underdischarging. That being said, if you don't have smart chips managing your battery (handheld power tools often just run the battery flat and cheap chargers just let the battery cook) you should manage the charging and discharging yourself. Here are some pages with good advice for doing that: http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries http://preview.powerelectronics.com/mag/504PET23.pdf http://www.techrepublic.com/blog/five-apps/five-tips-for-extending-lithium-ion-battery-life/289 --Guy Macon (talk) 19:27, 25 February 2013 (UTC)

Does exercise really result in weight loss?
Science writer Gary Taubes says exercise has no effect on weight loss. On the other hand, the mainstream medical establishment believe in "calorie in-calorie out" theory of adiposity, i.e. if you spend more energy than you eat, you will be lean, if you eat more than you spend, you will be fat. Is it really true exercise does not result in weight loss? If so, then why do we see so many people who claim they lost weight after exercising? I could not find any scientific criticism of Taubes' claim regarding exercise. Is his claim right or wrong? If Taubes' theory is right, then how could the heaviest person Manuel Uribe lose 400 kg (597 kg to 200 kg) after diet and exercise program? And if Taubes is wrong, why there is no scientific criticism? --PlanetEditor (talk) 03:42, 25 February 2013 (UTC)


 * This is very individual. I personally have definitely had periods of long-term weight loss success based mainly on exercise.  But it all depends how your calorie intake responds to an exercise program.  Some people may get hungrier and eat more; other people may find that the exercise relieves stress that they had been treating with food, so they actually eat less (or at least not much more).  --Trovatore (talk) 03:46, 25 February 2013 (UTC)


 * It very much depends on your assumptions:


 * 1) If you start to exercise, without changing anything else, specifically your diet, then you should lose weight (or at least gain it more slowly than before), as the same number of calories are going in, and some of those are now being burnt by exercise.


 * 2) If you also increase the calories you consume, because the exercise makes you hungrier, then you might still lose weight, see no change, or even gain weight, depending on if the additional calories consumed are more or less than those burned by the exercise.


 * However, in any case, exercise should make you healthier, by converting fat to muscle, etc. (assuming you don't pick a dangerous or injury-prone exercise). Also note that the fastest way to lose weight is to both cut calories and exercise, although such rapid weight loss may not be healthy. StuRat (talk) 03:49, 25 February 2013 (UTC)


 * This is a common question on Ref Desk, and StuRat has given you a good common sense answer. For lots of discussion on this, search Ref Desk archives for "exercise weight loss" (see the search filed at the top of this page). See for example http://e.wikipedia.org/wiki/Wikipedia:/Reference_desk/Archives/Science/2010_July_1#Weight_loss.  I'll summarise here:  If, over a sustained period of time, you eat the same calorific value as you did before, but increase your physical effort, then the increased mechanical energy you expend has to come form somewhere - if not from the food, then it MUST come from metabolising body mass - there is no other source.
 * I worked for a few years for a large company who had a large office tower. Floors 1 and 2 were a calls centre - about 200 women sitting at desks answering phones.  Floor 3 was the staff canteen.  Call centres are renowned for fat workers, due to sitting on their arse for hours at a time doing nothing but talk and click the mouse, maybe push the odd keyboard key. But some women were trim and remained trim.  Some women were fat and just got fatter the longer they worked there.  Guess which ones walked up the stairs to go to the canteen to eat their subsidised food?  Guess which ones always took the lift, just to go up or down one or 2 floors?.  Guess which ones parked their cars in free parking a kilometer away and walked the remaining distance?  Which ones used paid parking next door?  Yup - you got it - its the fat ones who didn't do any walking - every time.
 * Wickwack 124.178.143.40 (talk) 04:38, 25 February 2013 (UTC)


 * Since nobody seems to have mentioned it, note that replacement of fat with muscle might not result in "weight loss", in that muscle is heavier than fat. Probably less important for a 400 pounder than for somebody trying to get from 175 to 170. Gzuckier (talk) 06:35, 25 February 2013 (UTC)


 * That will occur if the degree of exercise and food intake are sufficient. However, it does not, and can not, change what StuRat and I said above:  If food intake is not increased, then over a sustained period of time, increased exercise MUST reduce your weight.  In fact, weight will go down whenever a regime of food digestable calorific value greater than body metaboloic need + mechanical energy produced is sustained.  The ratio of muscle mass to fat mass might well change, but total body mass MUST go down.  In theory, there are a couple of factors StuRat and I did not cover (they were covered by people posting in response when this question was asked before - did you check the archives?): 1) Expelled faeces contain unburned calorific value; and 2) the metabolic uptake of the brain is dependent of how hard it works (including how hard you think/concentrate on problems).  However, variation in brain metabolic uptake is not in practice great enough to make a noticeable impact on total body mass, unless you do silly thinks like use drugs to sleep most of the 24 hours in a day.  The body also has minimal ability to improve digestion efficiency - and the reason why faeces have calorific value is becasue that calorific value is in things like celulose fibre that humans cannot digest.  Wickwack 60.230.230.154 (talk) 07:06, 25 February 2013 (UTC)


 * And another minor factor is how well hydrated the person is. If they sweat heavily as a result of the exercise, and don't drink more fluids to replace those fluids, they may also lose weight by being dehydrated.  Not healthy, of course. StuRat (talk) 07:14, 25 February 2013 (UTC)
 * True. And taking a duretic (herbal or prescription dug) will reduce weight. Eating more salt will, by causing water retention, increase weight. although in healthy people gnerally middle aged or younger, the kidneys are very effective in getting rid of excess salt. However, significantly modulating your weight by any of these methods will eventually cause other medical issues - as you said - not healthy.  Wickwack 60.230.230.154 (talk) 07:24, 25 February 2013 (UTC)

What being physically fit does is that it makes your weight less dependent on your calorie intake. E.g. my weight has been stable at 60 kg during the last 4 years or so. I eat approximately 3500 Kcal per day. If I eat 200 Kcal per day more or less, it would have zero effect on my weight, because my body is working much harder than the average body to maintain itself in its present super fit state. I can quit exercising for a week and eat 4000 Kcal per day and still have no weight gain at all. Some people are naturally thin and have a constant weight (without necessarily being very fit), see here. Count Iblis (talk) 13:10, 25 February 2013 (UTC)

Muscle weighs more than fat, so some types of exercise for some people may actually increase their weight. The thigh muscles, for example, can be particularly heavy when well developed. --Dweller (talk) 13:19, 25 February 2013 (UTC)
 * Yes, that's what Gzuckier said above, but how is it relevant? More correctly, muscle is more dense than fat.  But how much extra muscle mass do you gain by exercising more, over a sustained period?  For reasonable exercise levels, not a lot.  Think about it - an average office worker does not need to grow any muscle to go walking - he already has it.  His muscles will just run at a higher metabolism to provide the mechanical energy. And muscle is only about 15% denser than fat anyway - not enough to matter much - See http://en.wikipedia.org/wiki/muscle (last para under heading Types of tissue). Unless you eat more, fat will have to be burned - you will get thinner - and you'll weigh less, because the energy storage value of fat is abou 32 kJ/g whereas muscle build is about 12 to 16 kJ/kg.  I did weight training in my 20's.  And I did put on a lot of muscle mass.  But I ate twice as much food too.  Wickwack 60.230.197.212 (talk) 15:08, 25 February 2013 (UTC)
 * Thanks for explaining it, however I have problem understanding the energy storage value concept. the energy storage value of fat is about 32 kJ/g whereas muscle build is about 12 to 16 kJ/kg. please explain. Thanks. --PlanetEditor (talk) 17:24, 25 February 2013 (UTC)
 * You may be referring to the fact that I accidentally typed "kg" where I meant "g". Muscle isn'y that cheap to make.  If you meant your question as written, here's the answer:  In the case of fat, it's simple.  When the body is storing energy in fat, 1 gramme of fat mass is added for each 32 kJ stored; for each 32 kJ recovered for use, fat mass goes down by 1 gramme.  To build 1 gramme of muscle, energy is required, which must come from either food or fat, to the extent of 12 to 16 kJ/g.  However this is a rough guide only, and the body is not able to build or tear down muscle as well as it can make/consume fat.  Wickwack 60.228.241.158 (talk) 23:44, 25 February 2013 (UTC)


 * Also note that the amount of calories burned by aerobic excercise, while not negligible, is quite small. An hour of a typical aerobic exercise is worth less than a whopper - see . There are side benefits to training, like increased fitness and more muscle mass, which have a second- or third-order effect on weight, but it is very hard to exercise against an overly rich diet. --Stephan Schulz (talk) 14:01, 25 February 2013 (UTC)

Thank you everyone. --PlanetEditor (talk) 17:24, 25 February 2013 (UTC)


 * The "muscle weighs more than fat" statement is very relevant to dieters whose only goal is to lose weight, such as the subscribers to programmes such as "Slimming World" or "Weight Watchers". I've seen many women lose several inches from various points of their bodies, only to be dismayed at the weigh-in because the actual numbers of pounds lost has not met expectations. This causes more severe dieting and more exercise, which in turn results in more muscle mass, which in turn results in fewer pounds lost, which results in more severe dieting and more exercise... which may tip a younger person over into anorexia nervosa. Other diet plans such as Rosemary Conley's emphasise inches lost over pounds lost. So it's important to emphasise to (especially) young women dieters that poundage lost is just one of the ways in which diet and exercise plans work. --TammyMoet (talk) 21:34, 25 February 2013 (UTC)
 * The "muscle weighs more than fat" is one of the most missunderstood statements around. Check proper scientific literature - there is in fact only a slight difference as I said earlier - did you check the Wiki article I cited, or scientific literature?
 * One should be very carefull when considering "facts" given by anyone associated with the weight loss or dieting business. In the case of women, you need to take into account that under dieting, especially rapid dieting or the early stages of a sustained calory restricted diet, the female body is very selective in where it consumes fat.  Usually "spare tyre" fat and breast fat (unless the woman has inherited very small breasts) goes first, giving them a smaller clothing size.  Fat at the top of the legs goes next.  Fat in all sorts of hidden places of the body, such as within the chest, goes last.  This means that waist measurement and clothing size goes down faster than total fat loss, even if muscle mass remains the same.  Fat consumption in men is also selective, but the distribution of fat consumed first is different.
 * Wickwack 60.228.241.158 (talk) 00:05, 26 February 2013 (UTC)
 * I'm sure there is plenty of scientific literature regarding this. What I'm telling you is how this is perceived by dieters and how they use the statement (or not) in their lives. Some companies (such as the two I mentioned) will play on this to hook gullible dieters into their programmes and carry on paying their money every week to be publicly humiliated at the weighing scales. As with everything, where there's money there's charlatans. --TammyMoet (talk) 09:10, 26 February 2013 (UTC)

Exercise Is an Effective Intervention in Overweight and Obese Patients, Alansplodge (talk) 01:47, 26 February 2013 (UTC)

Ozone hole over Antarctica
We all know that there is a ozone hole over Antarctica. But Antarctica doesn't have any industry, factory, refrigerator, etc. Despite there is hole over Antarctica. Why is it so? Technologous (talk) 15:30, 25 February 2013 (UTC)


 * Because CFCs don't float straight up and stay still, they float around, until they are approximately evenly distributed. The good news is, since they've been banned, the ozone hole seems to have largely closed, as the CFCs gradually dissipated. StuRat (talk) 15:37, 25 February 2013 (UTC)


 * Have a look at Ozone_hole. Basically, the CFCs get transported from their sources around the world to polar regions, and then get trapped there due to a polar vortex. Once there, they remain concentrated for a long time, and facilitate ozone destruction. SemanticMantis (talk) 15:41, 25 February 2013 (UTC)
 * (post WP:EC, I do not believe that the CFCs are evenly distributed, I believe they are concentrated at the poles, as outlined in our article. I welcome referenced information to the contrary. Stu is right that the the ozone hole is not the problem that it once was. This is largely due to the Montreal protocol.) SemanticMantis (talk) 15:41, 25 February 2013 (UTC)
 * Actually, while it had stopped growing, it has not yet shrunk significantly. --Stephan Schulz (talk) 15:58, 25 February 2013 (UTC)


 * You will notice that the Ozone Hole (!)TM was discovered in the same year the first satellite that could detect it was launched. In other words, we have no reason to believe it didn't always exist.  Its cause is unknown. μηδείς (talk) 02:10, 26 February 2013 (UTC)


 * Not true. (Min_ozone.jpg) It was 320 in 1956. Sagittarian Milky Way (talk) 03:45, 26 February 2013 (UTC)
 * As an aside, I believe there is a typo in this diagram: Sources_of_stratospheric_chlorine.png -- shouldn't it read anthropogenic instead of antropogenic? I do not know how to change it, sorry.  DRosenbach  ( Talk 18:21, 26 February 2013 (UTC)
 * You've given as a source for a 1950 stat a graph without refs that goes back to 1980? I am old enough, Sag, to remember when this so called discovery was announced in the mid-late 80's. μηδείς (talk) 02:43, 28 February 2013 (UTC)

Why protein requirement is calculated on the basis of total body weight?
The daily protein intake, RDA or other protein requirement calculations, are based on g/kg or g/lb of body weight basis. But protein is required mainly for muscle, the fat mass of the body has nothing to do with dietary protein. They why the daily value is not calculated on the basis of the weight of lean body mass? Why is it calculated on the basis of total body weight (lean body mass + weight of fat)? --PlanetEditor (talk) 17:38, 25 February 2013 (UTC)


 * Just because most people don't know their lean body mass. Note that people with a lot of fat on them do also tend to have more muscle, in order to be able to lift all that fat.  So, it's not as bad of a method as it sounds.  If we really wanted to be precise, we should probably also increase protein requirements for growing children and pregnant or nursing women. StuRat (talk) 17:53, 25 February 2013 (UTC)


 * Do you have any reference for that? -- Jayron  32  18:09, 25 February 2013 (UTC)


 * For what ? StuRat (talk) 18:10, 25 February 2013 (UTC)


 * For anything you just wrote. -- Jayron  32  18:14, 25 February 2013 (UTC)


 * I don't think needing more muscle to support more weight needs a reference. How many 100 lb people can lift 300 pounds ?  Just about none.  How many formerly (adult) 100 lb people who now weigh 300 lbs can lift themselves up ?  Just about all.  Do you imagine they developed psychokinesis to lift themselves up, if not muscles ?


 * Or, look at it this way: If you wore weights around all day, would you gain muscle mass ?  Of course you would.  (Although there may very well be an exception for those who are bed-ridden, but that's a small portion of the obese.) StuRat (talk) 18:17, 25 February 2013 (UTC)


 * I'm not saying your statement is right or wrong, just that you shouldn't make assumptions on what people will and won't find self-obvious. Mainly because a) if it was so obvious it didn't need a reference, there's no need for you to say it in the first place and b) if it's not obvious enough that you had to mention it because you thought the OP didn't know it, you should include a reference to it.  I can find at least one source that says the opposite: "Obese people tend to have a lower percentage of muscle mass because of muscle atrophy and lack of exercise." and later in the same source "obesity can alter the neural pathways in a way that accelerates skeletal muscle loss."  So, we have at least one source that indicates that obesity can cause muscle loss.  -- Jayron  32  18:31, 25 February 2013 (UTC)


 * You're looking at percentage of muscle mass, not total muscle mass. Yes, the obese will have a somewhat lower percentage of muscle mass, but the actual amount will be higher.  Just to toss some wild numbers out, if the 100 lb person had 50 pounds of muscle, then, when they gain weight to become 300 lbs, they might have 100 lbs of muscle mass.  The percentage dropped from 50% to 33%, but the amount of muscle actually doubled.  So, if the OP was thinking the 300 lb person would only have the original 50 lbs of muscle mass, and therefore only need the same amount of protein to support that as they did when they weighed 100 lbs, this helps to clarify the situation.


 * As for your point a, there are many things which are obvious once mentioned, but which you don't tend to think of yourself. For example, if you asked "How do we know that ice is less dense than water ?", many people wouldn't think to answer "Because ice floats", but, once you tell them that, they would understand and agree. StuRat (talk) 18:40, 25 February 2013 (UTC)


 * The article says "obesity can alter the neural pathways in a way that accelerates skeletal muscle loss. (bold mine). You have not addressed this.  As I said before, I'm not terribly interested in what you find obvious or not.  I'm interested in what you can find verification for.  Telling me that you find something obvious doesn't help the OP find references to answer his questions.  You shouldn't be arguing with me, as that doesn't help the OP find references to his questions.  You should be finding references to the OPs questions.  And if the OP wants to know why ice floats, it would help to provide a link to articles like density so they can learn more.  -- Jayron  32  18:44, 25 February 2013 (UTC)


 * You have yet to produce a source which says the actual amount of muscle stays constant as people gain weight. Our lean body mass article lists formulas which estimate lean body mass, being roughly proportional to total weight and height.  StuRat (talk) 18:45, 25 February 2013 (UTC)


 * Look, I've never said you were right or you were wrong. I've said that you're the one, when making statements, upon which the burden of evidence lies.  You could be right for all I know.  All I am asking for is a little bit of evidence.  Not a lengthy argument about why you should be exempt, among everyone, from providing evidence.  -- Jayron  32  18:54, 25 February 2013 (UTC)


 * You said I have not addressed your source, as if your source says something counter to what I claimed, when it does not. See that article I linked to for references supporting my claim.  However, requests for references should be limited to cases where you genuinely question the accuracy of a statement.  Otherwise, we waste our time hunting down sources to prove the obvious. StuRat (talk) 18:57, 25 February 2013 (UTC)


 * Again, forget everything I have said which is distracting your from this core concept: We have no way of knowing one way or the other if what you say is correct if you don't provide a reference for it. I'm not saying what you have said is wrong, what I am saying is that we don't know if it is correct.  Those are not the same thing.  Everything else I said above was my mistake, and not in any way should be addressed.  The only thing I want addressed is a source or reference for your statement, so that we can know one way or the other.  You made the positive assertion, it's your responsibility to provide some evidence.  -- Jayron  32  20:03, 25 February 2013 (UTC)


 * As I did. Now, would you like me to challenge you to provide sources for everything you say, no matter how obvious it is ? StuRat (talk) 20:46, 25 February 2013 (UTC)
 * You both know this "discussion" should go someplace else. But since the train has derailed, and we're discussing references, I'll note that a very high percentage of Jayron's answers contain at least one useful and relevant reference. I try to do the same myself, and I think we would all benefit if we used tried for the modest goal of one useful and relevant reference in each answer. SemanticMantis (talk) 20:56, 25 February 2013 (UTC)
 * I think you two should get a room. (smile) --Guy Macon (talk) 19:38, 25 February 2013 (UTC)

Nelson Mandela Bridge
What impact does the Nelson Mandela Bridge have on the lives of people living and working in Newton and surrounding areas — Preceding unsigned comment added by 37.228.107.19 (talk) 18:00, 25 February 2013 (UTC)


 * I added a title. StuRat (talk) 18:05, 25 February 2013 (UTC)


 * I've hear this question before: What impact does the Nelson Mandela Bridge have on the lives of people living and working in Newton and surrounding areas Well, they no longer get wet when crossing the river – unless they forget to use the new bridge.--Aspro (talk) 23:42, 25 February 2013 (UTC)


 * You might like to read City regeneration and the making of an urban experience : The Nelson Mandela bridge as sculpture. Alansplodge (talk) 01:37, 26 February 2013 (UTC)

Child cognitive development - how old does a child have to be to realize that money has worth?
How old does a child have to be in general to realize that money has worth in the sense that that child will say that "I choose the two quarters over the eight pennies, because two quarters is worth more, even though the eight pennies may look like a lot of money."? 140.254.121.34 (talk) 20:23, 25 February 2013 (UTC)


 * If it is explained to them at three or four, thay may well grasp the concept. Left to their own devices it may take until seven. They need practical experience of buying and selling things (trade and commerce)  to realise that the little silver things are worth more (by size) than the bigger copper things and that the paper-stuff is valued more  by their  older sibling -for vacuuming up coke. Be prepared for a lot of awkward questions along the way - which must answered honestly. --Aspro (talk) 20:44, 25 February 2013 (UTC)


 * They'd need actual math skills to compare 2 quarters to 8 pennies, but knowing a small dime is worth more than a larger penny they can learn at a fairly early age. StuRat (talk) 20:50, 25 February 2013 (UTC)


 * I assume you'll provide a link somewhere where we can read more about that? -- Jayron  32  20:58, 25 February 2013 (UTC)


 * Now you want sources to prove that comparing 2 quarters to 8 pennies requires math skills ? Shall I also include proof that 2 and 8 are, in fact, numbers ? StuRat (talk) 21:02, 25 February 2013 (UTC)


 * Its a fair question:This doesn't give any references but I suppose it is also based on the authors hard learned experience with his own kids.  Providing the sum doesn’t come to more that 10 units, even  very child can grasp 10 cents = one silvery small dime, and ten of those equal one dollar. This holds  even if they can't yet count up to one hundred. If we had eight fingers on each hand and  hexadecimal coinage they might be able to cope with 16 units – who knows. It's the 1,1's and 1,2's that come after 10 that throws  them. So it that sense, StuRat is correct. As Jane Jane Goodall et, al, have found, even chimpanzees can count – maybe, one day my time will come where I lean to master division and square roots of irrational numbers. Try and short change your four year old on his pocket money and you may find you have your proof - however, if you can, then blame his parents.--Aspro (talk) 22:05, 25 February 2013 (UTC)


 * Any 4-year old worth his salt will accuse you of shortchanging him no matter what. :-) StuRat (talk) 22:16, 25 February 2013 (UTC)


 * What maters most is weather s/he  or it, can give you a logic reason to challenge your creative accountancy (to use the current professional term). The argument based on “ I'll tell mom” though-often-very-effective, is not a display of numeracy and must fearlessly  be resisted; unless you’re having to sleep on the sofa for some transgression that even your  ex-girlfriends can't figure out.--Aspro (talk) 22:39, 25 February 2013 (UTC)


 * Any small child can be fooled by giving them some of these. They think themselves instant rich and no silly coins to deal with. CambridgeBayWeather (talk) 00:46, 26 February 2013 (UTC)


 * At least the pater doesn't have to sleep in the doghouse, during bad "whether". :-) StuRat (talk) 00:44, 26 February 2013 (UTC)


 * I don't think Canadian Tire money will solve the sofa problem. I do a mental check every, every time, of everything I've said... Nice dress, like the new hair style; wow, that baked potato was as good as anything I've had in Wendy's® . Then I might help her out by telling how my mom cooked stuff.  I can also  commiserate by saying things like  “Gosh., I wish I could revers into a parking space like that,  (pity about the fire hydrant and I have got to admit is was in the way..etc) .'' So no problems there.  So,  I just don't understand where she's  coming from.--Aspro (talk) 02:43, 26 February 2013 (UTC)


 * I think I was thinking of a different situation in which a child would count a limited number of coins on the table, but when the coins were spread out, the child thought that there were "more coins" or somehow it was "bigger" than it was, even though there were the same number of coins on the table. A similar situation would be when a child was given one cookie, and an adult was given two cookies. The adult broke the child's cookie into two pieces, and the child said it was "fair", even though those cookies were smaller portions. 140.254.121.34 (talk) 20:54, 25 February 2013 (UTC)


 * According to Piaget's theory of cognitive development, a child would need to be in the "concrete operational" stage of development, which is where they start to form logical connections and also begin to understand the concept of money, though the ability to understand money abstractly, and to be able to plan correctly and make wise purchases based on weighing comparative values and being able to consider worth abstractly (rather than merely accepting "price" as equal to "worth") is something that may have to wait until "formal operational" stage. Of course, there are other theories of child development out there, but I suspect that they would all broadly agree on the ages when these milestones would occur in children.  Wikipedia has an article titled Child development stages which states that a 5 year old "Recognizes and identifies coins; beginning to count and save money." however that article is fairly poorly referenced.  If you want some reading outside of Wikipedia on the development of a child's money sense, I did find this work which has a LOT of good research on this exact topic.  It provides a general overview of scientific research into a child's understanding of economic concepts, including money and worth.  -- Jayron  32  20:58, 25 February 2013 (UTC)
 * Yes, specifically Piaget's_theory_of_cognitive_development discusses some examples very similar to the OP's question, and I conclude that a child who knows 2 quarters is more money than 10 pennies has left Piaget's "intuitive thought" stage behind. SemanticMantis (talk) 21:09, 25 February 2013 (UTC)


 * I see your point. A child has three ways of learning. Experience, what it learns through guidance and explanation, observing and copying actions of others. If parents assume that 'schools' are the only place their children should  learn the academic things, then progress may be slower than it was before schooling became compulsory...Deschooling Society; 4-Year-Old Girl with Sky-High IQ Joins Mensa (I wonder if she can help me sort out my tax returns?) --Aspro (talk) 22:20, 25 February 2013 (UTC)


 * As far as I can tell, every child nowadays goes through this stage, where the parent says something like "We can't go to Disneyland, buy a big house, buy an airplane, whatever, because we don't have enough money", and the kid says "Why can't we just get more from the ATM?" Gzuckier (talk) 07:38, 26 February 2013 (UTC)


 * ATM confusion just does not apply to uninformed children. A friend's in-laws (or some such relatives) came over from India and wanted to be immediately show the nearest ATM that gave 'free' money. He explained (via his wife) that 'free' referred to the fact that these ATM's  (they had read about)  were referred to as 'free” because did not charge for crash withdrawals....  but that the withdrawer   had to have an account that was in the black to benefit from this arrangement. “But you have told us you have £20,000 pounds worth of free credit (about seven years salary for them).  We will be back home, long before before, we get can get forced  to pay it back! “ That had arrived expecting their investment on a flight to the UK would prove a money making bonanza. They went  home realising the streets of London where not paved with  gold and they had a son in-law that was a tight fisted b@%&'d for not letting them  access to his free credit card.--Aspro (talk) 18:01, 26 February 2013 (UTC)


 * Wang, A. (2010). Optimizing Early Mathematics Experiences for Children from Low-Income Families: A Study on Opportunity to Learn Mathematics. Early Childhood Education Journal, 37(4), 295-302. doi:10.1007/s10643-009-0353-9 states "It was found that after controlling for a number of variables, the extent to which teachers emphasized activities that build on skills such as telling time, using measurement tools accurately, estimating quantities, and knowing the value of coins and cash was a significant predictor of kindergarten mathematics achievement for both African American and Caucasian students from low income families," implying that by the age of five or so, children should be able to understand the value of coins.
 * Saxe, G. B., Guberman, S. R., & Gearhart, M. (1987). SOCIAL PROCESSES IN EARLY NUMBER DEVELOPMENT. Monographs Of The Society For Research In Child Development, 52(2), 1-137. doi:10.1111/1540-5834.ep11865217, discussing developmental processes in 2 1/2-4 1/2-year-olds includes a table with "Activities entailing numerical comparisons of at least two sets. Money equivalences.—I show him that five pennies are the same as a nickel. Sometimes I try dimes and quarters and their relations to the other coins." --some jerk on the Internet    (talk)  20:25, 26 February 2013 (UTC)