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September 19

Fight or flight

There are many articles which claims the fight or flight response can kill people with underlying heart conditions by causing plaque to become dislodged from an arterial wall and causing a blockage. But have there been any studies which has suggested that adrenaline and the temporary effect this has on the heart can cause permanent damage to even a healthy heart? Clover345 (talk) 00:17, 19 September 2016 (UTC)

Cortisol has some fairly serious effects long-term in psychological stress; trying to assess the risk of a single fight-or-flight episode sounds like a hard experiment... haven't looked yet though. Wnt (talk) 02:50, 19 September 2016 (UTC)

Every morning, one of the things that helps us wake up is a surge in catecholamines - the body's stress hormones - such as adrenaline. Healthy hearts deal with that, as well as surges in adrenaline and norepinephrine which directly mediate fight or flight response by preparing all the body's muscles, including the heart, for increased exertion.

What damages the heart muscle is starvation of blood, and that happens either during occlusion of one or more coronary arteries or by sustained exertion when the body's not getting enough oxygen or enough energy from food.

Diseases of the neuroendocrine system such as pheochromocytoma can cause extremely high blood pressure and damage arteries in the heart and throughout the body. Once the lining of an artery's been stretched enough to tear, tissue builds up to heal the torn arterial lining. Arterial plaque forming over these healed tears can limit blood flow through arteries - the reason why it's so important to control one's blood pressure.

Of course, high blood pressure can damage the heart for less exotic reasons, such as poor lifestyle choices (no exercise, excessive dietary intake of carbohydrates, untreated diabetes mellitus) and heredity (African-Americans tend to suffer from hypertension more than the general population, for example). These are separate causes from changes in catecholamine levels.

So, yes, sustained high levels of catecholamines can damage the heart - but only indirectly by damaging the arteries physically. The direct cause of this damage is untreated hypertension. Changes in stress hormone levels in the blood don't damage the heart in and of themselves - otherwise, athletes would be at abnormally high risk of heart disease. The reverse is true, even moderate physical activity, which causes enough stress hormone activity to drive muscles to perform more than usually, lowers the risk in most people of heart disease. loupgarous (talk) 18:12, 20 September 2016 (UTC)

True but doesn't adrenaline, for example, as a result of strong fear of something or strong nervousness/anxiety about something normally cause stronger heart beats than when exercising? 2A02:C7D:B942:B800:F425:97C4:9C9B:D3A8 (talk) 22:31, 22 September 2016 (UTC)

In animal welfare studies, cortisol is often used as an indicator of stress. Blood cortisol indicates immediate responses to the environment (acute), salivary cortisol indicates a slightly delayed response (perhaps 10 mins), faecal cortisol more delayed (perhaps 24 hrs) and then cortisol in the hair integrates responses over a long period of time. Chronically elevated levels of cortisol have been linked with shortened life-span in captive elephants (amongst other welfare concerns). DrChrissy ^(talk) 18:42, 20 September 2016 (UTC)

We tackled the issue from different ends of the cascade. Cortisol and ACTH kick off the cascade, so they are reliable indicators of stress. Out of curiosity, in these studies, was proximate cause of death specified for those animals who died sooner than the norm and had chronically elevated cortisol levels? I'm curious. loupgarous (talk) 19:12, 20 September 2016 (UTC)

Bombardier_Dash_8#Series_400 one engine taxiing

I recently took a flight on a Bombardier_Dash_8#Series_400 and was quite surprised when it taxied with only the right side engine running after landing. Here's a video (from someone else) of it in action[1]. How come the asymmetrical thrust doesn't make the plane veer to the left? Pizza Margherita (talk) 03:32, 19 September 2016 (UTC)

This practice appeared around 2005-2010 (?) and is widespread, especially for turboprops and for four-engine heavies. It depends on the airport and is part of agreed practices between the operator and the airport: most national regulatory bodies permit it, I don't know any who explicitly forbid it, a few aircraft types don't support it, whether it's done "in general" is up to the airline and whether it's actually done depends on the airport layout and the anticipated taxi time. Obviously long taxis and waits encourage it. Hundreds of pounds of fuel could be saved by eliminating a taxi and long wait for a 4 engine.

Rotating a body (in the most general sense of Newtonian mechanics) requires a couple, not just a single force, even one that's off centre. So provided that the only force is from the engine, then it need not cause it to rotate. However if another force is introduced, such as some less than gentle braking, then it will yaw and maybe to an unexpected and surprising degree. This is a technique for pilots with a light touch! It does limit the tightness of the turning radius for taxiing aircraft, so some layouts (and gates) may be more accepting of it than others.

These are modern brakes, with well-modulated control (subtle movements on the pedals give subtle braking, not sudden grabbing), so there is plenty of control that way. The Dash 8 here is a turboprop, so there's a good wash over the tail, even at low speeds, giving good control from that too - but not for the sort of precise manoeuvring needed around a modern airport. With turboprops, the engines may both be running, but one prop is feathered - this still gives most of the fuel saving, but is a little quicker for a getaway once clear to go. A question about this practice is the risk of causing a serious delay if the aircraft taxis out, then fails in some way. It's unlikely, but we know how congested airports are.

The choice of which engine to use may also be dictated by the direction of the turns anticipated. A starboard engine will turn left much more easily, and that could be influenced by the layout at particular airports.

To discuss further, Prune is the place for sensible airliner talk. Andy Dingley (talk) 09:11, 19 September 2016 (UTC)

Andy, just one minor point about your excellent answer: a rigid body will rotate about its centre of mass under the action of one force if its line of action does not pass through the centre of mass (as is the case when running on a single left or right engine). To keep the plane moving in a straight line, an asymmetric force from the contact force of tyres on the runway (or other steering as you mention) is required to produce an opposing couple about the centre of mass, thus keeping the plane moving in a straight line. Dbfirs 12:07, 19 September 2016 (UTC)

Agreed. See torque. StuRat (talk) 17:33, 19 September 2016 (UTC)

I can't make any sense out of that. If the engine delivers a steady force, and the plane moves at a steady rate, then there must be an opposing force of equal magnitude. I'd expect to find that no closer to the engine than the nearest landing gear. Wnt (talk) 12:12, 20 September 2016 (UTC)

Don't forget there's the weathervane effect of the fuselage, the rudder, most aircraft have differential braking (i.e. separate left and right brake pedals), and larger aircraft usually have tiller steering via the nose wheel as well. I.e. you have a good selection of features to keep the aircraft pointing in the correct direction. A quick search tells me the Dash 8 should have all of those. When you combine that with the fairly minimal thrust used for taxiing, it's not really such a big deal in terms of the physics. Pilot skills 101 includes taxiing when the wind is trying to turn you off the tarmac onto the grass, and keeping the aircraft straight on the runway with crosswind effects during takeoff and landing; so a small amount of offset thrust isn't such a big deal. Modern pilots have it incredibly easy, with ABS brakes, and steerable nose wheels. Tail draggers are a whole extra set of skills on the ground, in comparison, to the point where the likes of the RAF Battle of Britain Memorial Flight have to keep ancient tail dragger basic trainers around to convert their highly skilled pilots to their WW-II aircraft. Murph9000 (talk) 13:37, 20 September 2016 (UTC)

Andy's last sentence presumably refers to PPRuNe, the Professional Pilots Rumour Network Internet forum. -- ToE 13:14, 19 September 2016 (UTC)

I don't fly multi-engine aircraft, so I don't know very much about taxiing them - but I'm willing to bet that this procedure has more to do with actual real asymmetric thrust - P-factor - than it has to do with saving fuel. The Dash is probably not saving any meaningful quantity of fuel - because the same amount of energy has to be used to taxi, which-ever engine the fuel is flowing into - and in relative terms, turboprops idle efficiently! P-factor means that the center of thrust is not in the center of the prop - not in the center of either prop - the thrust is offset to the side of the engine. Multi-engine aircraft can be particularly susceptible to P-factor because their props are not on the aircraft center-line, so the moment-arm is even longer than a single-engine airplane. It seems reasonable to believe that in some aircraft, if the yawing moment is powerful enough, it is desirable to keep the thrust coming out of the engine whose center of thrust is most close to the aircraft's center-line. In other words, the pilot of the Dash may be choosing to use the critical engine only, during ground-operations.

I looked in the Airplane Flying Handbook, and I did not see any mention of this procedure in the Ground Operations section of the Transition to Multi-Engine Aircraft chapter. If the answer actually matters, the person you should ask would have to be a multi-engine flight instructor!

Nimur (talk) 18:36, 19 September 2016 (UTC)

They presumably run less efficiently, the further from their ideal cruising speed they are. Also, using more fuel implies more air pollution, and that might be an issue, too. StuRat (talk) 17:09, 20 September 2016 (UTC)

I have an example that might help you to understand. Ever had a shopping cart/buggy with a wheel that's "wonky" and wants to turn the cart one way ? I find I can sometimes keep it going straight if instead of pushing it equally on both sides, I only push on one side. Very similar situation of off-center application of force, the plane just manages to simulate the "wonky" wheel. StuRat (talk) 22:50, 20 September 2016 (UTC)

Thanks, all! Pizza Margherita (talk) 04:35, 20 September 2016 (UTC)

Resolved

September 20

Glucose instead of fructose

Isn't glucose better for you than fructose? If so, why don't people just put glucose in their coffee instead of white sugar, which is half and half? Anna Frodesiak (talk) 04:52, 20 September 2016 (UTC)

Sucrose (white sugar) is not "half and half" glucose and fructose, it is a different substance formed by the reaction of glucose and fructose with the loss of water (ie. glucose + fructose → sucrose + water). It is true that sucrose hydrolyses to a 1:1 mixture of glucose and fructose, and that that process is much faster in acidic environments, but sucrose has its own properties (include sweetness separate from those of glucose and fructose). White sugar is a product of sugar cane which contains easily extractable sucrose but relatively little free glucose. It does contain glucose polymers (cellulose) as a structural material, but this is not easily converted to free glucose. By contrast, potatoes have starch as their glucose polymer which is easily converted back to glucose, so sugar cane may not be an ideal source for glucose. Even if the sucrose from sugar cane was hydrolysed, there would be need to separate the fructose and approaching half of the mass of sucrose extracted would be lost as (waste) fructose, so it is unlikely to be economically attractive. Further, the fructose would likely not be cost competitive with high fructose corn syrup due to the subsidies. Fructose is sweeter than glucose but metabolised much faster so it is a desirable additive from a business perspective (less is needed for a given sweetness) but undesirable from a health perspective - because you are correct that glucose is better than fructose from a health perspective. EdChem (talk) 05:23, 20 September 2016 (UTC)

From the "better for you" point of view I would humbly suggest no sugar in your coffee. Richard Avery (talk) 06:50, 20 September 2016 (UTC)

Or put some L-Glucose in your coffee. Count Iblis (talk) 07:02, 20 September 2016 (UTC)

See also: Glycemic load --Hans Haase (有问题吗) 09:22, 20 September 2016 (UTC)

Hi Richard Avery. Actually, I don't use sugar in coffee and rarely eat anything sweet at all. Anna Frodesiak (talk) 01:56, 21 September 2016 (UTC)

Sorry Anna Frodesiak, I did not mean to imply that you did. It was bad wording on my part. If more people in developed countries followed your example there would be more healthy people in the world. Richard Avery (talk) 06:25, 21 September 2016 (UTC)

No need to say sorry, my friend. There's nothing wrong with saying "...I would humbly suggest no sugar in your coffee...". :) Anna Frodesiak (talk) 06:58, 21 September 2016 (UTC)

I don't deny publications about fructose and diabetes, but it seems absurd to call a major natural sugar "unhealthy". There are unhealthy people who need specialized diets, but fructose is part of the human evolutionary story and the body is reacting to it according to a carefully regulated procedure. That procedure just doesn't take into account every modern trend.

If you're going to use a different sugar, you can use grape sugar, i.e. glucose Gee, I wonder if "powdered raisins" or lyophilized raisins exist as a thing... I'm not seeing it, but it seems like it might be neat for such purposes., or stevia and erythritol, which to me seems like the perfected version of an artificial sweetener at least until somebody's patents expire and some dread side effect is published to get us on to the next thing. Wnt (talk) 12:08, 20 September 2016 (UTC)

Grapes were not the main diet during human evolution. Modern grape varieties like the red seedless grape accentually contain more fructose than glucose. We are also omnivores. It is only in a blink of the eye (in the time-line of human evolution), that so much convenience food has included such high sugar content, available not just seasonally -but all year round. It is not the natural sugars per sa (as you point out) that should considered unhealthy but the vast quantity the are now being consumed to the detriment of our evolutionary omnivorous needs.--Aspro (talk) 20:04, 20 September 2016 (UTC)

Inulin used to be added to stevia-based sweeteners, and I found it improved the taste of stevia in my coffee. Inulin's got a number of health benefits (it's a soluble fiber and incrases calcium absorption in young women, and is metabolized only about 35% as much as other carbohydrates) but makes some folks gassy and can aggravate irritable bowel disease and related diseases. I don't know if that's why no one puts it in their stevia sweetener any more, or just that straight stevia's cheaper to make and sell. I eat a lot of beans anyway, so a little more gas is no issue. I guess I need to check out local health stores for inulin. loupgarous (talk) 18:48, 20 September 2016 (UTC)

Yes, the problem with eating sugars has more to do with not getting enough fibers as a result and fibers are the food for gut bacteria who convert it to Short-chain fatty acids which we need: "The short-chain fatty acid butyrate is particularly important for colon health because it is the primary energy source for colonic cells and has anti-carcinogenic as well as anti-inflammatory properties[7] that are important for keeping colon cells healthy.[8][9] Butyrate inhibits the growth and proliferation of tumor cell lines in vitro, induces differentiation of tumor cells, producing a phenotype similar to that of the normal mature cell,[10] and induces apoptosis or programmed cell death of human colorectal cancer cells.[11][12] Butyrate inhibits angiogenesis by inactivating Sp1 transcription factor activity and downregulating VEGF gene expression.[13]" Count Iblis (talk) 20:19, 20 September 2016 (UTC)

I'm curious as to why you refer to "fibers" rather than "dietary fiber". Is that what it's called on your planet ? :-) StuRat (talk) 20:46, 20 September 2016 (UTC)

Yes, adding "dietary" is too much effort for me :) Count Iblis (talk) 02:32, 21 September 2016 (UTC).

I'm more curious about the "s" you added at the end. StuRat (talk) 17:17, 21 September 2016 (UTC)

Hi User:EdChem. But from what I understand, sucrose is just fructose and glucose and your body just splits it into two easily and then processes each seperately. Is that right? If that is the case, and economics aside, can one not just buy a jar of glucose or use corn syrup (which I think is glucose) and stir that into coffee and not tell the difference and be healthier? Best, Anna Frodesiak (talk) 01:56, 21 September 2016 (UTC)

Beware of simple-minded "this is healthier than that" comparisons. I suppose there are some (water is healthier than arsenic, say), but in general they don't tell the whole story.

Fructose is fruit sugar. It's the main thing that plants use to bribe animals to carry their fruit around and spread their seeds. Presumably the animals wouldn't do that if it were a terrible thing per se.

Also consider that fructose is sweeter than sucrose, whereas glucose is less sweet than sucrose. See the table at sweetness#Examples of sweet substances. So even assuming, for the sake of argument, you would come out ahead by replacing fructose with glucose gram-for-gram, you might use more grams of glucose if you sweeten to the same taste.

That said, I'm not saying you're wrong. Maybe you really would come out ahead. But I don't think your arguments thus far convince me of that. --Trovatore (talk) 02:23, 21 September 2016 (UTC)

I don't think corn syrup tastes as good as cane sugar. When US soda pop companies switched from sugar to corn syrup, the result just didn't taste as good, and sales have started to lag due to this and other reasons. StuRat (talk) 02:25, 21 September 2016 (UTC)

Hi Trovatore and StuRat. There's only one way to know. If either of you have a can of corn syrup, why not add the equivalent amount as white sugar to a coffee and let us know. :) I would be very curious to know the answer. I would do it, but I don't like sugar. I find it addictive and it makes me start shrieking in the night, although that could be caused by the monsters. I've been having a problem with monsters lately. Anna Frodesiak (talk) 02:49, 21 September 2016 (UTC)

So first of all, corn syrup also has fructose. And other things, which may be what Stu is tasting. As for me, I take my coffee black, like any self-respecting coffee snob. --Trovatore (talk) 03:18, 21 September 2016 (UTC) Actually that's not entirely true — I do often put cream in brewed coffee, though not in espresso. But no sugar in either case. --Trovatore (talk) 03:20, 21 September 2016 (UTC)

So what product is just pure glucose? Anna Frodesiak (talk) 04:06, 21 September 2016 (UTC)

Well, you can buy actual glucose. I found it easily on Amazon, for example. --Trovatore (talk) 04:08, 21 September 2016 (UTC)

No kidding? Come to think of it, we have the Glucose Barn and The Glucossery just round the corner, or if want the five-gallon drum, there's the Bulk Glucose Shopper's Club. Seriously, can't someone there do a taste test and let us know? There must be some product in your cupboard that is just glucose. Anna Frodesiak (talk) 04:19, 21 September 2016 (UTC)

There "must"? Why? As far as I know, the only product that is just glucose is what is sold as "glucose". --Trovatore (talk) 05:59, 21 September 2016 (UTC)

Well, Trovatore, I figured there ought to be some product that is just glucose, considering that it's just sugar, and a preferable sugar, health-wise. Heck, if I used sugar in recipes and had a jar of glucose handy, I'd reach for that over sucrose. Wouldn't you? Anna Frodesiak (talk) 06:23, 21 September 2016 (UTC)

The "preferable health-wise" part is not clear to me. But in any case, as far as I know, if you want to buy just glucose, it's going to say "glucose" on the package. Or possibly "dextrose". If you find out otherwise, I'd be curious to hear about it. --Trovatore (talk) 06:47, 21 September 2016 (UTC)

Hi Trovatore. Well, everything I've read says that bodies handle glucose better than fructose. Anyhow, if I find glucose, I may buy it and try it. Anything to reduce the night-shrieks. :) Kidding. Cheers, Anna Frodesiak (talk) 06:58, 21 September 2016 (UTC)

Hi Anna, the taste of sucrose is different from that of glucose, fructose, or a mix of the two. Even if after hydrolysis in the stomach your body treats sucrose as a 1:1 mix of glucose and fructose, the difference in taste will be notable in the mouth as you consume it and before any significant processing has occurred. Further, L-glucose, the enantiomer of D-glucose (which is the naturally occurring form) are identical in taste but the L-form is not metabolised as a regular sugar would be, and so has the sweetness but not the calories. Swapping one compound for another frequently gives unanticipated consequences in a system as complex as a living animal. Certainly, given the differences in sweetness and glycemic properties, the amount of glucose required to produce identical sweetness (and that doesn't mean taste, necessarily) will not be 1:1 with sucrose or fructose. To produce identical glycemic load will also be a different amount. Comments above that the health issue is much more about the large increase in sugar consumption of all types so recently that substantial evolutionary adaptation is only beginning are highly relevant, in my opinion. EdChem (talk) 08:03, 21 September 2016 (UTC)

Yes, the taste of glucose (which I have been given when my blood sugar is low at the doctor's office) is markedly different from sucrose, and not something a kid would like as candy, to be sure. μηδείς (talk) 18:09, 21 September 2016 (UTC)

Thank you everyone. This has been very educational. By the way, regarding the large increase in sugar consumption, 10 years ago here in Haikou, you'd see a fat person once a year, no kidding. Today, it seems like 20% of women are fat-obese, lots of men too, and students are really putting it on. What's changed? Sugary drinks and products everywhere. Sugar cane has always been something they ate, but it never made them fat. Oh, and people are richer, so they can afford more fatty food too. Maybe that's a factor. Anyhow, thanks again to all. Anna Frodesiak (talk) 23:01, 21 September 2016 (UTC)

Scotch and water

Apparently adding water to scotch is a thing[2][3][4]. These sites purport that water somehow "opens up the flavors of Scotch" in some way, and one[5] even says "A chemical reaction occurs between the water and the tightly-wound chains of amino acids in the whisky."

But what's really happening here? Is there actually a measurable effect or is this all just the placebo effect?

And is all that stuff a about a chemical reaction possible? I remember from high school that when you have a equation like:

A + H20 = B

And then given enough time to react then it will reach chemical equilibrium with the concentration of A, B, and H20 all reaching some stable point. A bottle of whisky has plenty of A, B, and H20 and it has had more than enough time to react. So I don't see how adding a few drops of water, which is a negligible amount compared to the amount of water already in the scotch, could shift the equilibrium in any noticeable way. Pizza Margherita (talk) 07:16, 20 September 2016 (UTC)

An explanation here. Mikenorton (talk) 10:14, 20 September 2016 (UTC)

"Did you also know that water warms the whisky? Yep, that’s right. As you add water to the whisky, you are mixing two different liquids, each with different arrangements of molecules that are simultaneously mutually attracted and repulsed. Since the attractions are stronger, the liquid stays together. As you mix whisky and water together, you have to break the attractions and reform a new equilibrium of attractions and repulsions. Mixing water with whisky causes the attractions to be a little stronger, that is to say, that they form stronger intermolecular bonds. Try mixing 10 ml of water and 10 ml of ethanol, you get LESS than 20 ml of liquid because the molecules are grabbing hold of each other more tightly, or bonding. When bonds are formed, molecules move less, giving up their energy, in this case heat. This heat then contributes to a temperature rise, we call this the heat of mixing."

What's the heat of mixing for adding 0.5ml water into 50ml of 50% water/50% alcohol solution? I'd like the check whether that actually makes a significant difference or not.Pizza Margherita (talk) 22:46, 20 September 2016 (UTC)

This may help [6], but I've not had time to go through it in detail - see also Ethanol (data page). Mikenorton (talk) 14:46, 21 September 2016 (UTC)

And another here. Mikenorton (talk) 10:17, 20 September 2016 (UTC)

To be sure though, I'd expect amino acids to be quite rare in whiskey, especially as long polypeptides. Not unless somebody dumped a protein supplement into it. Wnt (talk) 11:58, 20 September 2016 (UTC)

Another possible effect is that, by diluting the ethanol, the other flavors become more apparent, as ethanol tends to overpower other flavors in strong concentrations. Note that this effect may vary by the taster, as some are genetically more sensitive to the taste of ethanol. See TAS2R38#PROP_sensitivity.2C_supertasting.2C_and_alcoholism. StuRat (talk) 16:56, 20 September 2016 (UTC)

Old saying: The proof of the pudding is in the eating. The OP now needs to experiment. Personally, I am a bit of a heathen during the winter, when I enjoy the odd dram or two in a sort of brandy glass (of this type) to savour the bouquet , but to get the full flavour a little water is required. For long cool drink however, do not use tap water. Although, tap water is wholesome and safe to drink it is totally unstable for all spirits as it has been chlorinated (producing unpleasant tasting chlorophenols) and brighteners such as aluminum compounds which have been added to the mains supply. Use either (glass not plastic) bottled 'soft' spring water (i.e. those with little calcium) or use just an ordinary home water filter (I use a Britawhich produces acceptable results) – and if you whant to add ice... make sure that those too has been made from spring or filtered water. P.S. Boil (in a clean glass vessel) in the microwave before freezing and you will get much clearer, transparent ice cubes, as the boiling drives off most of the dissolved gasses so doesn’t produce all those little bubble that cloud the ice. Finally, always choose a good malt. They needn’t be the very expensive ones, just avoid the blended grain whiskeys. They are as bad as the American Bourbons. Then sit back and Enjoy!--Aspro (talk) 18:29, 20 September 2016 (UTC)

Oh, this was all going good, until that last unnecessary insult. Bourbon isn't Scotch and shouldn't be evaluated by the same criteria. It's like saying rum isn't very good Scotch. Have you tried Maker's Mark? --Trovatore (talk) 18:42, 20 September 2016 (UTC)

In fact, I've always said: "Rum isn't a very good Scotch." General Ization ^Talk 18:46, 20 September 2016 (UTC)

I've drunk in English pubs (at one point I lived over one for a month) and I think I see the issue. Most pubs in Great Britain have Jack Daniels, and that's all the Bourbon they have. Maker's Mark is better, but Weller's Special Reserve is the standard by which Bourbon ought to be judged - a single malt sour mash which makes the mouth sing with pleasure. Judging all Bourbon by Jack Daniels is almost exactly like judging all Scotch by an indifferently-made, mass-marketed blended Scotch whisky (like J&B). I don't drink any blended whiskies, Scotch or Bourbon, they actually give me indigestion. On the very rare occasions I drink at all, it's Weller's or the Glenlivet. loupgarous (talk) 18:57, 20 September 2016 (UTC)

Judging ANY bourbon by Jack Daniel's is a bad idea because Jack Daniel's isn't bourbon. It's Tennessee sour mash whiskey. Jim Beam is a bourbon. If one must have a mass market bourbon, the best is probably Maker's Mark, while Evan Williams makes a single-barrel bourbon which is pretty good. --Jayron32 19:14, 20 September 2016 (UTC)

Bourbon and Tennessee whiskey are legally separate categories, but to my no doubt unsophisticated palate, they seem close enough that I'm comfortable comparing them head-to-head. --Trovatore (talk) 19:22, 20 September 2016 (UTC)

Note that (safe) tap water is not chlorinated in many parts of the world. It's certainly not where I currently live. --Stephan Schulz (talk) 00:40, 21 September 2016 (UTC)

Ah. Here is a link on how to savour a single malt. Enjoy.--Aspro (talk) 21:00, 20 September 2016 (UTC)

I was honestly expecting to see a fellow pouring the whiskey over his shoulder while savoring a glass of "sparkling wine". :) Wnt (talk) 02:28, 21 September 2016 (UTC)

How about eating one chocolate malted milk ball ? :-) StuRat (talk) 13:22, 21 September 2016 (UTC)

• I agree with StuRat, but in Russia vodka IS water. μηδείς (talk) 00:05, 21 September 2016 (UTC)

A very good point μηδείς, it is indeed. Think I might just take a late summer holiday there and book into a hotel with an en-suite marbled bathroom that has hot & cold running Vodka.--Aspro (talk) 15:46, 23 September 2016 (UTC)

Feynman Lectures. Lecture 24 [7]

Explain me please formulas 24.3 and 24.4. Namely how did Feynman get that $\langle ({\tfrac {dx}{dt}})^{2}\rangle ={\tfrac {1}{2}}\omega ^{2}x_{0}^{2}$?

We have:
$\langle x^{2}\rangle ={\tfrac {1}{2}}x_{0}^{2};$
$x={\hat {x}}e^{i\omega t};$
$dx/dt=i\omega {\hat {x}}e^{i\omega t}=i\omega x.$

But $\langle (i\omega x)^{2}\rangle =\langle -\omega ^{2}x^{2}\rangle =-\omega ^{2}\langle x^{2}\rangle =-\omega ^{2}({\tfrac {1}{2}}x_{0}^{2}).$

So we get minus Feynman's result. Where is a mistake? — Preceding unsigned comment added by Username160611000000 (talk • contribs) 10:37, 20 September 2016 (UTC)

In this case, the velocity and the magnitude of the velocity are being used interchangeably, because, um... isn't it obvious? This is a little bit of sloppy physicist-math. Thinking like a physicist means making conceptual leaps - why do you care about the average velocity? (Hint: think back to your thermodynamics class). And if you can answer that, you'll probably see that the direction of the average velocity doesn't matter - so you can drop the minus-sign.

Last week, I wrote extensively on the topic of why Feyman's lectures are not really great for new students of physics - you have to already know all the material - plus you have to also know boatloads of other physics - if you intend to appreciate any of Feynman's insights and see his connections.

If you want a mechanics text that pulls no punches, but is written with a little more sensitivity to proper pedagogical methods, I can't recommend highly enough Classical Dynamics, by Marion & Thornton. It is written at a level that will appeal to an intermediate or advanced-novice student of physics who has not yet been introduced to every single mathematical method or physical application of theoretical physics. You will probably find no serious mathematical issues in that book - not even sloppy physicist math. If you're a true pedant, this is the book for you - casually flipping through my copy, I randomly landed on three independent pages in three independent chapters, for which the foot-note by Jerry Marion analyzes some ancient calculation of Josiah Willard Gibbs using some new mathematical method to derive more decimal-places of precision. This book is a real nail-biter, in terms of physics-textbook excitement and suspense.

If you'd rather read the Feynman lectures, just know this: the lectures are bad. We all know they're bad. Other professors at Caltech know they're bad. We can critique Feynman's work without dishonoring his legacy: he wasn't writing those course-notes for your audience. From the introductory editorial, including a discussion of nearly a thousand points of errata in his lectures, is this commentary: "Feynman was too slick... he knew tricks and what approximations could be made, and had intuition based on experience and genius that a beginning student does not possess."

My point is this: we can hand-hold you as you stumble through every equation, each week, from now until forever... but at some point you must admit to yourself that you're just reading the wrong book - for you, at this point in your education-level - and you will benefit by switching to a better book. For now, at least.

Nimur (talk) 13:12, 20 September 2016 (UTC)

Feynman lectures are not so hard, and I like them. I have already finished physics course for technical profession (but I want to get in-depth study, besides other traditional university textbooks on physics are much worse). So I'll continue to read the Lectures and if I find some trouble I'll write in this topic. So your answer is that formulas are correct, but we can just omit the minus sign, isn't it? — Preceding unsigned comment added by Username160611000000 (talk • contribs) 15:41, 20 September 2016 (UTC)

It seems we must take real part of $i\omega {\hat {x}}e^{i\omega t}$ which must be equal:

$i\omega (ix_{0}\sin(\omega t+\Delta ))=-\omega x_{0}\sin(\omega t+\Delta )$

So $({\tfrac {dx}{dt}})^{2}=(-\omega x_{0}\sin(\omega t+\Delta ))^{2}$. Now it's positive. Am I correct? — Preceding unsigned comment added by Username160611000000 (talk • contribs) 19:24, 20 September 2016 (UTC)

As the mathematicians say, the second-power exponentiation projected onto the complex plane is a twofold cover such that each nonzero number has exactly two roots.

As the physicists say: we're always gonna square it, so the sign doesn't matter.

Right?

Nimur (talk) 22:52, 20 September 2016 (UTC)

Right? -- No. Feynman warned against taking square of complex number:

if, for some reason, we want to use the square of $A$, it is not right to square the complex number and then take the real part, because the real part of the square of a complex number is not just the square of the real part

But it's just little weird for ${\tfrac {d}{dt}}$. — Preceding unsigned comment added by Username160611000000 (talk • contribs) 06:56, 21 September 2016 (UTC)

• Hmpf. Feynman lectures are not so hard, and I like them. - well, the question you ask proves that if anything that particular one was too hard for you.

I have not looked at the lecture itself, but those equations have harmonic oscillator written all over them. The error stems from the fact that the formulas $\langle x^{2}\rangle ={\tfrac {1}{2}}x_{0}^{2}$ and $x={\hat {x}}e^{i\omega t}$ do not refer to the same x. The first one applies when x is the real, physical position (i.e. $x=x_{0}cos(\omega t)$), the second one applies when x is the complex number "position" that is used as a trick to solve the differential equations (because it is easier to deal with exponentials than sines and cosines) (i.e. $x=x_{0}exp(i\omega t)$). The first one is the real part of the second. As a consequence, your fourth line is incorrect, because $\langle x^{2}\rangle =0$ for the second definition.

If you want to take the RMS of Y in complex notation, it is not $\langle Y^{2}\rangle$ but $\langle Y^{*}Y\rangle$, for no other reason than the complex notation is a calculation trick and $Y^{*}Y=|Y|^{2}$. Tigraan^{Click here to contact me} 09:42, 21 September 2016 (UTC)

I don't know if this is justifiable to say or not, you tell me, but my feeling is that, in general, the worse the university, the better the teaching. This is because a poor university hires someone to focus on teaching, who can deal with poor students, while a world-class university hires someone to do research and indulge the students at odd moments; also because (as a separate rule) you are always worse off with a professor who writes his own textbook, since you have nothing to fall back on. At the best campus you may end up being taught by a graduate student, which is great for his career but perhaps not as much for yours. There are exceptions of course, most notably, quacks and lazy profs who sometimes exert peculiar power at a poor university, but they are not that common. Wnt (talk) 17:27, 21 September 2016 (UTC)

Strange, but in the next chapter "24–2Damped oscillations" Feynman says that we should not take an imaginary part to eliminate $i$. We should do that only when we have 2 solutions. — Preceding unsigned comment added by Username160611000000 (talk • contribs) 12:53, 22 September 2016 (UTC)

Here is a book that will explain how to use elementary complex analysis for damped harmonic oscillator: Alciatore and Histand's Mechatronics. How frequently do you need to be reminded that Feynman's lectures are not easily-understood by most new students - they were not well-understood even by students who held the highest academic qualifications, the highest test scores, and were immersed in an incredibly supportive, cooperative, collaborative peer-group? This author's style is not suited for new learners. His descriptions skip over important conceptual explanations because his unspoken expectation is that his readers have already completed many years of prior formal instruction. His mathematical terminology is sloppy, his teaching-style baffled the most academically-gifted students in the United States, and his lecture notes are not used by most modern physics instructors at the university level, because they aren't a great introduction to the formal study of mathematical physics. Modern instructors do not even follow the broad or general layout of his course!

You're really committed to keep struggling through these lectures, nitpicking at minutia in class-notes that have been stale for over a decade (after over a thousand points of error were corrected by other professors). What you are reading is a sort of abridged and cut-up version that has the glossy veneer of Feynman on its front cover, but the text and equations come from Kip Thorne, Rudolf Pfeiffer, and dozens of other authors who worked in a not particularly coherent or cooperative fashion to edit this monstrosity. Wikipedia articles are written with better editorial control.

And guess what book those guys actually use when they run a class? (Kip Thorne runs the whole department, so you can be darned certain he has a stake in selecting the textbooks!) Hmm... not the Feynman lectures... Hand and Finch, Analytical Mechanics, because Caltech students are quantitatively, literally geniuses - and if that book is too difficult for you to read, they recommend Marion and Thornton - just like I suggested earlier!

Here's a hint: you aren't learning the material properly because you're barely understanding Feynman's notes, and even if you finally succeed, it ain't gonna impress anybody. Non-physicists are not going to care which boring math books you read; and physicists are just going to ask why you didn't read a better book. Want to impress a real physicist? Run the homeworks in Jackson's textbook.

The fact that you repeatedly struggle against this workload is simply demonstrating that you are so completely unprepared for the study of advanced physics that you can't even orient yourself enough to locate the proper study-material. Get a better book.

Nimur (talk) 15:21, 22 September 2016 (UTC)

Degreasing steel

I have already asked this question a few days ago, but it hasn't been answered: Which solvents (of the ones currently available) work best for degreasing stainless steel after machining? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 11:13, 20 September 2016 (UTC)

"Best" is a really unqualified adjective - are you concerned with environmental or health side-effects? If not, a really strong acid wash will take everything off! We have an article on pickling, which can be used to clean and to chemically treat the surface. Nimur (talk) 13:32, 20 September 2016 (UTC)

As the part in question is stainless, then pickling is also going to involve passivating it afterwards. Which you can do easily with some citric acid, just from a homebrew shop. Andy Dingley (talk) 13:45, 20 September 2016 (UTC)

As you didn't like the earlier answers, I suspect your question paraphrases as "What can I buy cheaply on the high street?". In which case an aerosol of disc brake cleaner (and not carburettor cleaner). This is a spray-on solvent mix, chosen for its ability to drain off with the oils and then the residue to evaporate cleanly afterwards. Other similar sprays in a car shop will leave some oily residues of their own, which you don't want. Andy Dingley (talk) 13:45, 20 September 2016 (UTC)

Xylene can also be used. Count Iblis (talk) 16:49, 20 September 2016 (UTC)

We used to use Toluene and a sonicator for removing fingerprints from the small metal lenses we used in mass spectrometers after removing them to clean the soot off of them. But xylenes are roughly the same. --Jayron32 16:54, 20 September 2016 (UTC)

The best solvent for degreasing stainless steel after machining is a n-propyl bromide based solvent in a vapor degreasing machine. I recommend the SharperTEK US-WC, available at ultrasonics direct starting at USD $14,200.00.[8] Check the tank size to see if your part fits, and I would strongly recommend the subzero secondary and filtration options. And no, you will not be happy if you just try the n-propyl bromide without the vapor degreasing machine. --Guy Macon (talk) 17:00, 20 September 2016 (UTC)

The answer really depends on what processes the stainless steel item is going to be subjected to next and how long it is going to be in storage before the next process. If it is a simple, effective degrease, there are many (one that hasn’t been mentioned but we used a lot is Trichloroethylene) but if it is going to be bonded (with say) an epoxy resin then a acid pickle is called for. Even, domestic washing-up detergent works for many things. We really need to know the context.--Aspro (talk) 18:57, 20 September 2016 (UTC)

What's wrong with plain old acetone or methylated spirits ? Vespine (talk) 22:37, 20 September 2016 (UTC)

Are they as effective as TCE? Because I have to degrease the part thoroughly -- I can't have cutting fluids or other organic impurities in my reaction mixture! 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 09:10, 21 September 2016 (UTC)

Methylated spirit is bright purple and stinks of pyridine. It leaves both behind as a residue. Andy Dingley (talk) 12:40, 21 September 2016 (UTC)

Then methylated spirit (did you mean denatured alcohol?) is not an option for me. As for acetone, is it as effective as TCE? For that matter, is toluene/xylene as effective as TCE in degreasing? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 22:01, 21 September 2016 (UTC)

Acetone is variable. It's somewhat hard to get (bomb precursor controls - as is isopropanol, for drug precursor controls). It can be quite awkward to get a clean grade of it - if it's in plastic gallon cans, then it won't be that clean.

Acetone is my go-to workshop degreaser, because I don't like working with trike outside of fume extraction. It would probably do you. But then so would most things, provided they evaporate cleanly, and you can get hold of them. Andy Dingley (talk) 12:48, 22 September 2016 (UTC)

[un-indent] The item will be used as part of a chemical reactor (hence cleanliness is very important), and it will not be bonded with any adhesive or coating. So all I'm looking for is an effective degreasing. Thank you for all your answers -- I think I'll go with TCE (unless someone suggests an even better option), or if I can't get it, then my second choice will be brake cleaner. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 00:34, 21 September 2016 (UTC)

Trichlorethane ultrasonically agitated.--86.187.166.72 (talk) 01:46, 21 September 2016 (UTC)

Sorry I meant trichlorethylene--86.187.166.72 (talk) 01:49, 21 September 2016 (UTC)

Ah, now we know the context we know that this means laboratory standard ultra-clean. Which is a lot higher than most industrial engineering standards. However, industries that fabricate integrated circuits for instance require extreme degreasing because even pico-grams of contaminants will lower production yields of viable IC's. A thing I learnt in tribologyis that such machined surfaces have a very thin solid–liquid interface. It is a sort of macromolecule emulsion of metal and oil. It is only in the order of about half a micron thick but can be seen clearly under an electron microscope. Not even TCE can remove this. So it depends on the surface to volume ratio of you apparatus as to whether is this level of possible contamination is acceptable. So, to save you coming back here again – do what I would have done when I worked in R&D. Find out from the machinist the exact grade of SS and the supplier. Telephone their technical dept and explain your exacting requirement. Try to speak to a human rather than email. They may not know but may be able to suggest an metallurgical institution or some-such that can provide more reliable guidance than we can't reasonable be expected to do here without us (me) asking for a consultancy fee and you haven't even fully explained what your reactor is. Good luck with what must be some ultra secret experiment.--Aspro (talk) 16:42, 21 September 2016 (UTC)

Well, a half-micron layer solid-liquid interface probably won't hurt anything, so I'm sure such a high standard won't be necessary. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 22:05, 21 September 2016 (UTC)

Yes, my gut reaction is that you can probable get a way with just a thorough degrease but wanted to warn you about the worst case scenario - ending up with possibly bum results and wasted time. As you are probably working on a small budget then consider this. If your using a balloon type reactor, the advantage of SS is that if you scour it with just soapy water and get down to base metal, the SS forms a thin, transparent, and impervious oxide layer – problem solved. To understand more about what I mentioned about the 'contamination' layer that one just can't remove with TCE or most other degreasing solvents see out article section Parts cleaning. Note: In this article is give a value of > 1 µm for the 'deformed boundary layer' for the macromolecule emulsion of metal and oil but it is in the same order of magnitude for freshly machined parts, which may well not matter in your application. Use your own judgment here. Sometimes, simple solutions work just fine. A plastic kitchen scouring pad and 'washing soda' may be all you need – also very cheap, non carcinogenic and very often efficacious. P.S. Just out of curiosity: What are you synthesizing?--Aspro (talk) 17:39, 23 September 2016 (UTC)

Unlike many of the people here, I know nothing of this topic. Still, I have the vague sense that nasty stuff like TCE is supposed to be phased out and replaced by cleaner solutions like supercritical CO2, and I'll give this source [9] in support of the idea, though I don't know what it means in real-life terms. I'm thinking if people have to use expensive equipment and design something finicky, might as well challenge them to go green... Wnt (talk) 03:04, 22 September 2016 (UTC)

September 21

Image noise

When set the ISO of a camera to a high setting, meaning the amount of light that's required to hit the sensor to achieve a tone is decreased, the image gets grainy. The same thing happens in your eye in the dark— things look grainy. Why is this happening? Is it a property of light, or a problem with all light sensors?

You may wish to read our article on the topic at Image noise. The problem can be due to noise in the sensor, or down to the photons of light that come in one at a time. Graeme Bartlett (talk) 00:30, 21 September 2016 (UTC)

Your eye does not have light sensors whose sentsitivity can be adjusted. It has separate sensors that work in dim light and bright light, called rods and cones respectively. Only the cones are sensitive to color, so in dim light you can't see colors much. The part of your eye with the greatest density of sensors, the fovea, contains only cones, so in dim light you see with other parts of your eye that do not give as good a resolution. Thus what's going on is completely different from effects in a camera, though it may produce similar results. --69.159.61.230 (talk) 05:16, 21 September 2016 (UTC)

Interesting that in the days of film, ISO was a measure of grain size. 400 ISO film was larger grain than 100 ISO film. --DHeyward (talk) 05:12, 22 September 2016 (UTC)

Well, it was a measure of film speed. The 400 film would have larger grains if it used the same chemistry as the 100 film.

A linguistic note: "ISO 400" is not actually the correct way to write the film speed; it's "ISO 400/27". It was previously called "ASA 400" or "DIN 27", and the ISO standard just combined the two numbers from the earlier ASA and DIN standards. The DIN standard used smaller numbers because it was logarithmic: ASA 200 was DIN 24, ASA 100 was DIN 21, etc. If you're just talking about 400, you might as well call it ASA. All three abbreviations, ISO, ASA, and DIN, are the abbreviated names, or former names, of the standards organizations that respectively promulgated these particular standards. Again, see film speed. --69.159.61.230 (talk) 06:13, 22 September 2016 (UTC)

Modern digital cameras report an "equivalent" ISO value because this is a parameter that consumer photographers wish to use. In actual fact, a digital camera's "ISO value" is a best-effort to configure the digital system (or to report its automatic configuration), distilling many complex and independent variables into one scalar number.

In some respects, a digital camera's ISO value represents the total gain applied to the image. In other respects, the ISO value reflects a model of the sensor and processor's signal to noise ratio in a fashion that is meant to correspond to photographic film.

In broad brush-strokes, we can say that using a higher ISO value will yield both a "brighter" image and a "noisier" image. When we compare two different images captured on two different digital cameras whose reported ISOs match, the intent is typically to make their exposure equivalent, and their signal-to-noise ratios will vary as a free parameter.

There are many problems with this simplified model. First, noise in digital cameras can be quite complex. Even defining the signal-to-noise-ratio is a challenge of both engineering and of basic optical science. Frequently, we just assume gaussian noise and let some sophisticated automatic mathematical system analyze and estimate noise for some ideal reference image.

Another problem is that gain in a digital camera is not simple, either. Even if we ignore the internal details - like the fact that gain can be applied many different times, or that different gain may be applied to different parts of the picture in various spatial-, frequency-, or color- tranform domains - all of which a film camera generally cannot do! - we still have the problem that gain need not be a scalar value either. Consider only the most obvious of these issues: the gamma equation tells you that your gain is non-linear. Well, here's some bad news for the enthusiasts who want to use their digital camera as a scientifically-accurate photon-to-electron- transducer: even the most elementary and archaic electronic circuits use automatic, non-linear application of gain. Your camera's image-sensor contains millions or billions of transistors. Each of these millions of independent circuits need not behave passively - let alone identically !

The image may experience gain at every single stage of its processing pipeline - from nonlinear optical attenuation, to nonlinear photoelectrical coupling, to nonlinear digital signal processing. From all these stages, one must estimate an effective, average gain. You're trying to determine which coefficient you use to multiply the input-photon count that will yield the 8-bit number in RGB color-space in your output picture. Well, ... that's an overly-simplified model!

ISO rating is a dramatically inapt way to represent the image that is produced by a digital camera. But, it's the value that people want, so a lot of computational effort goes into estimating it.

The ISO standard, ISO 12232:2006 publishes several reference algorithms to standardize this methodology... but it costs something like a hundred US dollars to buy their spec sheet, and who has that kind of money to burn on their digital camera hobby?

Nimur (talk) 15:58, 22 September 2016 (UTC)

Nimur has explained it, but even I as a photographer, had trouble following it ;¬) There must be a simpler way of explaining the signal to nose ratio and its connection with gamma compression which contributes to the graininess. Will have a stab at it, never the less. Light falling on each pixel represents 'information'. If no light from (say) the shadows on a moonless night are falling on the sensor, then the camera records mostly the sensor noise. Should the light level gets up-to (say) 254 bits in blazing sunshine, the noise (which is still there) is swamped by the extra information and is no longer perceivable, since the percentage of noise is a very small fraction, compared to the light signal. Or in other words, in blazing sunshine the light information is hitting the sensors faster than the 'noticeable' noise is being generated. Therefore if one set ones camera to a too higher ISO it will show grain because it has not been given enough time to gather light information. --Aspro (talk) 19:03, 23 September 2016 (UTC)

I apologize that my answer was not as clear as I had hoped.

Let me try to re-orient towards the original question.

The usual root-cause of "graininess" in a digital image comes from two places: shot noise and thermal noise. (There are many other noise sources with different physical sources, but we can ignore them for today's discussion).

When a digital camera raises its ISO value, it usually does so by boosting its gain. This does two things:

1. It permits the camera to collect a similarly-exposed image using a shorter exposure time. This reduces the total number of incident photons, and the inevitable and purely-mathematical consequence of that change is that the statistics of the photon shot noise are amplified in magnitude. For example, if we're collecting 100 photons and we get one single stray photon, we might say we have "1% noise;" compare this to a smaller photon-count: if we only expose for half as long, we expect to collect 50 photons - but now, one single stray photon is "2% noise." This is literally and actually quantum physics at play, creating a real, visible, observable effect inside a toy that the average person can play with! Just be careful with taking this simplification too far - it's harder to know which photon is the noise photon - which of the 51 identical particles was the one you didn't want to count?! So, you can see how the simplified explanation breaks down pretty quickly. In this example, we'll expose for half as long, so we get about half as many photons, but ...we're about to use "an amplifier" to multiply the count by two - and we should get an image that looks the same, even though the "shutter speed" was half as long!
2. It also boosts the gain, which may include analog gain. Every electrical circuit implementing an amplifier has both a gain and a non-zero noise figure. Therefore, thermal noise is added to the output signal, because the circuit is made of real devices that are made of real atoms and electrons with actual, non-absolute-zero temperatures. This process degrades the signal-to-noise ratio. In tandem with that additive process, all other noise that was already present in the signal - including the input signal's thermal noise and the photon shot noise - gets amplified by the gain (though this does not affect the ratio relative to the signal).

The end-result is that you see more noise, visually. The character of that noise is often called "graininess" because it looks very similar to the photochemical granules in old photographic film technology. Professionals who study digital image signal noise may prefer to use more specific or accurate terminology based on the mathematics/statistics/physics/engineering analysis of that noise. We care how gain got applied: what type of transistor, what type of circuit? Digital or analog? How hot was the device? How much of that heat is caused by inefficient photoconversion of incident-photons in the diode, and how much of that heat is static dissipation of the electronics around the photodiode? Details!

So, that's why the general rule of thumb is that high ISO yields both brighter pictures and more graininess. The rest of my discussion was intended to emphatically explain why ISO is a poor measure of this effect: there are so many additional confounding factors that make the details even messier - to the extent that I might go so far as to say the following: the rule of thumb does not apply equivalently to all digital cameras, and ISO is a terrible way to measure or characterize a digital image.

But, we use it anyway, because it's possibly the most universally-appreciated system we've got. Sometimes, a simple, one-parameter model is good enough for most people.

Nimur (talk) 19:52, 23 September 2016 (UTC)

Blood pressuer: white coat syndrome and its opposite

Hello. I understand that white coat hypertension is where a person's blood pressure is higher in a doctors surgery than it normally is in their daily life. In the UK the NHS gets around this by using home blood pressure monitors to get an accurate reading away from the surgery.

My question is. If blood pressure can be affected by mood and stress (ie. the stress of being in a surgery can make it go up) and made to look artificially higher than it really is, surely it can also be affected by relaxation and calm and made to look artificially lower than it really is. If a patient who panics around doctors takes their blood monitor home but then listens to calming music, closes their eyes, lies down for a bit, then does their reading... surely that's just as inaccurate/unrepresntative as their panicked reading at the surgery? — Preceding unsigned comment added by 213.120.143.245 (talk) 10:20, 21 September 2016 (UTC)

It's kind of funny; any time I go to see the doctor, the intake nurse will check my blood pressure, which will invariably be just over 140/90, even if I have been sitting comfortably for 5 minutes. Then the doctor will come in and say my blood pressure is a bit high, and will retake it, and it will have dropped 15 points to 125/75. μηδείς (talk) 18:04, 21 September 2016 (UTC)

The objective is to measure the patient's resting blood pressure. When the patient is at home, listening to calming music, closed eyes etc. that IS resting so the machine should achieve an accurate measurement of resting blood pressure. It isn't possible to observe a blood pressure significantly below resting blood pressure, unless the patient is using drugs or other medication for that specific purpose, and that would be unwise. Dolphin (t) 12:30, 21 September 2016 (UTC)

Off-topic discussion of one user's personal blood pressure experience. This is not an anecdote desk. SemanticMantis (talk) 13:50, 21 September 2016 (UTC)

Then there's the problem I have, that a blood pressure cuff constricting my arm makes me extremely uncomfortable and thus raises my BP, regardless of where I am or what music is playing. StuRat (talk) 13:14, 21 September 2016 (UTC) Maybe you could use a little self-psychology and pretend to like it? ←Baseball Bugs What's up, Doc? carrots→ 13:27, 21 September 2016 (UTC) It's not a mental issue, it's a physical one. I can't wear anything tight on my skin, as my skin then breaks down. I don't wear a watch or any jewelry. Before I switched to contact lenses, my glasses damaged the skin on my ears where they rested, creating open sores. StuRat (talk) 13:45, 21 September 2016 (UTC) I think you should take this to your doctor. ←Baseball Bugs What's up, Doc? carrots→ 15:09, 21 September 2016 (UTC) No need for that, I have the cure already, I just don't wear anything constricting (incidentally, this includes shoes, so I take them off while driving and as soon as I go inside). I do need an alternate way to take my BP, though. StuRat (talk) 17:24, 21 September 2016 (UTC) That's not a cure, it's a workaround or coping mechanism. ←Baseball Bugs What's up, Doc? carrots→ 19:04, 21 September 2016 (UTC) Life is all about coping. Cures are not well defined in general, e.g. the fact that we're fur-less apes makes us wear clothes. That's a coping mechanism, but few would want a cure in the sense of a drug that would give us back our lost fur. Count Iblis (talk) 19:32, 21 September 2016 (UTC) Reminds me of W.C. Fields' cure for insomnia: "Get plenty of sleep!" ←Baseball Bugs What's up, Doc? carrots→ 19:36, 21 September 2016 (UTC) Let them spend some time with the Tsimane people "Though the San, Tsimane, and Hadza often average less than seven hours of sleep, they seem to be getting enough sleep. They seldom nap, and they don’t have trouble dozing off. The San and Tsimane languages have no word for insomnia, and when researchers tried to explain it to them, “they still don’t seem to quite understand,” Siegel says." Count Iblis (talk) 20:04, 21 September 2016 (UTC) There are people who have a much more serious situation along this line (Epidermolysis bullosa) due to weakness of skin proteins. (I'm thinking anything like this will have a long tail of people with minor mutations who aren't affected enough to count as having the disease, but have weaker function than the average person) There's an article about someone imaging the lesion caused by some idiot putting a blood pressure cuff on them here but I didn't access the text. Apparently there is a "noninvasive blood pressure monitoring" scheme, involving direct pressure only, that can be used on them but in this paper even that was avoided - I think they just didn't take it. But a lot of other papers talk about putting wool padding under the cuff and then taking the pressure almost normally, which seems uninventive to me. Surely there is some bulk property of fluid that changes with pressure and could be measured remotely! Wnt (talk) 03:20, 22 September 2016 (UTC) Isn't there a finger cuff ? That would at least limit the discomfort, although I understand that they aren't particularly accurate. Fortunately I know when I have high BP, as I feel my own pulse in my ears (feel, not hear). High sodium intake does this to me, as I also have sodium sensitive hypertension. I have lots of health issues, but fortunately they all seem quite minor. But if I started taking meds for them all I would soon have major medical problems, due to all the side effects. This happened to my Dad, who took blood pressure meds, that caused kidney failure. (Even sitting causes me discomfort, so I am going to make a standing desk, right now.) StuRat (talk) 14:42, 22 September 2016 (UTC) Done ! I pulled a drawer out on my desk, put a wooden plank on the drawer, put a printer box on that, and my keyboard and mouse on top. I then put the monitor on top of my desktop PC, which is sitting upright on my desk, and now I have a standing desk. MacGyver has nothing on me ! :-) StuRat (talk) 14:58, 22 September 2016 (UTC)

"To measure your resting heart rate and blood pressure, pick a time when you’re feeling relaxed, Dr. Faulx advises. Randomly sampling both measures throughout the day can also help you reach an average." - From the Cleveland Clinic, here [10].

There isn't just one blood pressure, as indicated in my link above, it changes during each heart beat, let alone other factors. Resting, ambulatory, and mean blood pressure are all used in modern medicine. Here [11] is a paper that discusses a bit about resting vs. ambulatory blood pressure, and how they are measured. Here [12] is an article about 24 hour mean blood pressure, and here [13] is an article that uses resting blood pressure. SemanticMantis (talk) 13:50, 21 September 2016 (UTC)

If your arteries are in bad shape, they will be stiff and then a small amount of stress will lead to a significant rise in BP. Healthy arteries will expand a lot more in response to stress or exertion, so the blood pressure will actually not rise all that much. The same is true for your heart rate and this is then also affected a lot by your physical fitness. While your resting heart rate will be quite a bit higher if you are not physically fit, what also happens is that it will stay elevated due to recent minor exertions for lot a lot longer. But I can then get the opposite effect where the hart rate goes down so fast after a short exertion that it will undershoot the normal resting value and then climb upward to the resting value. E.g. I have measured values as low as 34 bpm just after a short exertion like running up stairs while my resting heart rate would typically be around 38 bpm. Count Iblis (talk) 17:40, 21 September 2016 (UTC)

Can cheese be made with unsaturated fat only ?

To start with, if you use skim milk to make cheese, does that work ? Of course, not having any fat would make it rather unappealing, so perhaps some vegetable oil with little or no saturated fat could be added back in. Keeping it from separating might require a treatment like they give Miracle Whip.

Or, perhaps fake processed cheese, made entirely from vegetable oil, could be made from all unsaturated oil ? I would expect that you might get a liquid cheese, but that could be put in a bottle and sold that way.

So, using any of these techniques, could you make a cheese, whether a solid bar, semi-soft cheese in a tub, or liquid in a squeeze bottle ? Is there any such product out there now ? (NOTE: I do not want to discuss the health effects of saturated fats, if you want to do that, please open a new Q.) StuRat (talk) 13:43, 21 September 2016 (UTC)

Yes, you can make cheese with skim milk. For example, here [14] are instructions for how to make ricotta using skim milk. Wikihow also [15] has some cheeses that can be made with skim milk. SemanticMantis (talk) 13:53, 21 September 2016 (UTC)

Good, then can we add in unsaturated oils so it has a better texture ? StuRat (talk) 14:39, 21 September 2016 (UTC)

That's a good question, and one I don't really know how to answer. Or rather, I do know how, but I can't do it for you. Experiment! The ingredients are fairly cheap, and only you are qualified to say when you think the texture is better. Another one to try might be paneer. It's incredibly easy to make, I've used wikihow instructions for that too. If you want more discussion before you dive in, I'd recommend you chat for a few days with the good folks at CheeseForum.org - they seem to have a lot of users with a great deal of cheesemaking experience for a variety of methods and cheeses. SemanticMantis (talk) 15:37, 21 September 2016 (UTC)

Vegan cheese exists, you could check the ingredients and processing to see if that meets your requirements. --Jayron32 14:10, 21 September 2016 (UTC)

I tried those, and didn't like them. StuRat (talk) 14:34, 21 September 2016 (UTC)

Not to harsh your vibes, but there's no such thing as a vegetable oil with absolutely no sat fats. Something like high-oleic sunflower will get you in the single digits, but it's still not zero. shoy (reactions) 15:13, 21 September 2016 (UTC)

Is there no way to separate the saturated from the unsaturated portions ? Even if not, we could still hopefully reduce cheddar cheese, from saturated fat content being 2/3 of the total fat, to under 1/3, using something like grapeseed oil. StuRat (talk) 15:34, 21 September 2016 (UTC)

Can saturated fats be removed from vegetable oil ?

...in order to make an entirely unsaturated oil, which is still edible ? StuRat (talk) 01:09, 22 September 2016 (UTC)

Removing all traces would be hard, but industrial and laboratory procedures exist for separating saturated and unsaturated oils, typically by exploiting differences in their melting point, e.g. [16][17]. Assuming you used a process that doesn't introduce inedible contaminants, I don't see any reason the separated oil wouldn't be edible, though the taste and cooking characteristics would be somewhat different. The only commercial cooking oil to be processed in a way that significantly reduces saturated fat that I know of is diacylglycerol oil which results in ~97% unsaturated fats (though removing saturated fat is not actually the immediate intent of the processing). I would suspect that the cost of processing to remove saturated fat is seen as too high in most cases to justify making such a product, especially since there are many cooking oils that are already ~90% unsaturated. Dragons flight (talk) 11:36, 22 September 2016 (UTC)

What kind of price increases would it take ? Considering how expensive some oils are, like quality olive oil, hopefully you could make an unsaturated oil less expensively than that, if you start with a cheaper oil, like grape seed oil, that's already low in saturated fat. StuRat (talk) 13:41, 22 September 2016 (UTC)

Assuming the process is fractional distillation based on melting point, and thinking about similar processed foods, my wild ass guess is that one would add somewhere between $5 and $30 to the cost of a 1 L of cooking oil. Dragons flight (talk) 14:10, 22 September 2016 (UTC)

That sounds like a reasonable price for a healthy vegetable oil. StuRat (talk) 02:13, 23 September 2016 (UTC)

Also, have to ask, to what end would one want to remove ALL saturated fats? --OuroborosCobra (talk) 11:41, 22 September 2016 (UTC)

One obvious reason is for nutritional studies. Feed one group of people food made with the normal oils (the control group) and feed another group the same food made with the oils with all the saturated fats removed, then measure if they have any significant differences in weight, blood chemistry, blood pressure, etc., after the trial period. Then, if the unsaturated oil is found to be healthier, you may have a marketable product. StuRat (talk) 13:38, 22 September 2016 (UTC)

Is saturated fat a risk factor for cardiovascular disease ?

(I broke this off as a separate Q, since, as I said in my Q, I'm not interested in discussing this now. StuRat (talk) 15:53, 21 September 2016 (UTC))

Whether saturated fat is a risk factor for cardiovascular disease is a contentious question:

Systematic review	Relationship between cardiovascular disease and saturated fatty acids (SFA)
Harcome, 2016	"The current available evidence found no significant difference in all-cause mortality or CHD mortality, resulting from the dietary fat interventions. RCT evidence currently available does not support the current dietary fat guidelines."
Ramsden, 2016	"Available evidence from randomized controlled trials shows that replacement of saturated fat with linoleic acid effectively lowers serum cholesterol but does not support the hypothesis that this translates to a lower risk of death from coronary heart disease or all causes."
de Souza, 2015	"Saturated fats are not associated with all cause mortality, CVD, CHD, ischemic stroke, or type 2 diabetes, but the evidence is heterogeneous with methodological limitations."
Schwab, 2014	"there was convincing evidence that partial replacement of SFA with PUFA [polyunsaturated fat] decreases the risk of CVD, especially in men."
Chowdhury, 2014	"Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.".

References

See Inuit diet, Maasai people#Diet, French paradox, Israeli paradox. --Guy Macon (talk) 15:50, 21 September 2016 (UTC)

In a society where everyone smokes, let's do studies where we compare smoking heavy cigars to lighter cigarettes. The results will be conflicting, as cigar smokers tend to smoke less than cigarette smokers. RCTs could be done but in the end you're comparing one bad thing to another bad thing but they cause problems in slightly different ways. Also, the results ending up not being not so clear will be totally distracting from the fact that smoking in general is bad. But no such studies would be done in a hypothetical society were everyone smokes, where not smoking is totally out of the question.

Now compare smoking to eating fat. Not eating any fat is "out of the question" as we all eat fat, we only ask if saturated fat causes problems relative to unsaturated fat. But let's now consider if fat in general is healthy or if it causes adverse health effects. Note that just like smoking is not necessary for health, there is no nutritional reason why you need fat in your diet at all apart from a few grams of Omega-3 and Omega-6 (which you can get from vegetables and who whole grains). So, let's see how the people who live in primitive society where no cooking oil at all is used fare w.r.t. people who live in societies where cooking oil is used. If you e.g. compare people in rural Uganda to people living in the West you find results like this:

"Maybe the Africans were just dying early of other diseases and so never lived long enough to get heart disease? No. In the video One in a Thousand: Ending the Heart Disease Epidemic, you can see the age-matched heart attack rates in Uganda versus St. Louis. Out of 632 autopsies in Uganda, only one myocardial infarction. Out of 632 Missourians—with the same age and gender distribution—there were 136 myocardial infarctions. More than 100 times the rate of our number one killer. In fact, researchers were so blown away that they decided to do another 800 autopsies in Uganda. Still, just that one small healed infarct (meaning it wasn’t even the cause of death) out of 1,427 patients. Less than one in a thousand, whereas in the U.S., it’s an epidemic."

The study on which this was based was one of the earliest papers in which the idea that cholesterol levels were linked to heart disease was put forward. But at that time this idea was not taken serious, it was decades later until this idea gained traction and today everyone knows about it. What happens is that if you stick to a plant based diet eating only small amounts of meet, don't use cooking oils and as a result eat a lot more (whole grain carbs) your cholesterol level becomes a lot lower.

But the most damning evidence against oils comes from studies that show that even olive oil is bad for heart health in an absolute sense (when you don't compare different Western style diets to each other but only look at the effect of the olive oil), see e.g. here. Now, one may look at other studies that suggest that polyphenol rich extra virgin olive oil seems to be not so bad or perhaps even good for the heart. But then the bigger picture here must surely be that if the olive oil itself is bad, then the polyphenols are just compensating for that, it doesn't make the oil good.

Intervention studies are i.m.o. best done in indigenous populations who still stick to eating a plant based diet low in oils. Take 100 such people and put half of them on a diet with a lot of olive oil and then see which group develops more cardiovascular disease. Such tests should be very sensitive to small effects because we already know that the control group is free of cardiovascular disease. Such studies have never been done but we do know that the zero heart disease rate in thee populations is not due to genetic factor. E.g. in this article where the focus is on salt consumption, it is pointed out that the Yanomamo Indians don't get heart disease despite their very stressful lives. But when they move away from the jungle to live in modern civilization they tend to drop dead from heart attacks and strokes just as everyone else there.

While one can fault such arguments as not being 100% rigorous, it should be clear that had we started out eating plant based diet in past centuries then the FDA would never have approved the use of any oils, salt and many other of the common food products we use today. The burden of proof would be on people claiming that oils can be safely used to prove that it doesn't lead to more heart attacks relative to a plant based diet. Count Iblis (talk) 18:44, 21 September 2016 (UTC)

Some dietary fat does seem to be necessary for life. See rabbit death. StuRat (talk) 21:07, 21 September 2016 (UTC)

Indeed. In fact, the claim that "the human body is designed to burn carbs, not fat" is unsupported by science and should not be given as an answer on the refdesk. Cut your protein intake to 0% and you die. Cut your fat intake to 0% and you die. Cut your carbohydrate intake to 0% and your body produces carbohydrates, allowing you to live normally. That being said, adding a multivitamin, non-digestible dietary fiber and Resistant starch is probably a good idea for anyone on a low carbohydrate diet. --Guy Macon (talk) 22:00, 21 September 2016 (UTC)

Yes, but the essential fatty acids that we cannot make ourselves are Omega-3 and Omega-6 fatty acids and you can get these from vegetables and whole grains. If you don't eat any fats, you'll need to eat quite lot of carbs so, it's then quite easy to get enough of the essential fatty acids. Count Iblis (talk) 21:56, 21 September 2016 (UTC)

Did you actually read our article on Rabbit starvation? You need fat to survive. You need a lot of fat to survive. It doesn't have to be animal fat, of course; millions of people are living healthy vegan lifestyles. They do need to take care that their diets have enough fat and protein, but that isn't hard to accomplish. --Guy Macon (talk) 22:33, 21 September 2016 (UTC)

Think this fear of saturated fats can be traced back to a sales and marketing ploy that was promoting Canola. They cherry picked research. Guy Macon gave a reference to the Inuit (think Inuit is the correct plural – if it isn't I am going to have lot of Inuits correcting me) . They had a very low CVD problem despite their high saturated fat consumption until they adopted 'healthy' southern diets. Think the researcher that has be most able to lay it out clear and explain the importance of a balanced fat diet is Udo Erasmus, who spent 6 years researching the nutritional and industry literature to properly understand the effects of oils and fats on human health. [18] His book provides a comprehensive bibliography that shows the broader view. In more resent years the sales and marketing lie has been exposed. For instance: The science of saturated fat: A big fat surprise about nutrition?. This is one of many. Don't think any budding nutritionist at college today would swallow (pun not intended) the saturated fat fallacy.--Aspro (talk) 18:53, 21 September 2016 (UTC)

See here, and also consider that it's quite difficult to get all your energy needs from fats. The human body is designed to burn carbs, not fat (diabetics can get Diabetic ketoacidosis where the body poisons itself due to burning fat when insulin levels are too low). If you put people on a low carb diet they develop insulin resistance, and they perform a lot worse on fitness tests. I know quite a lot of obese people and they all eat unhealthy fatty diets. When they see me eat (plate after plate of potatoes or whole grain pasta), they wonder how on Earth I can eat that much and be so thin. But that's only because they've been indoctrinated about the dangers of eating a lot, particularly carbs. They are eating foods that don't give them enough energy to be physically active. Thing is that there aren't all that many people who are obese and stick to eating a high calorie low fat, high carb diet with plenty of vegetables. Almost all obese people eat a junk food diet that actually isn't all that high in calories. Count Iblis (talk) 19:58, 21 September 2016 (UTC)

I do not believe that your claim that "If you put people on a low carb diet they develop insulin resistance" is supported by the science. See , which says " Reductions in dietary carbohydrate should be used as a strategy to treat insulin resistance." --Guy Macon (talk) 21:33, 21 September 2016 (UTC)

References

Yes, but then these people already have insulin resistance, and then it's well known that a low carb diet works well. In more recent work it has been shown that type 2 diabetes can be reversed using a low carb diet (at least some of the people could stop using all medications). But this does not mean that such a diet is optimal for healthy people who don't have insulin resistance or diabetes to begin with. Note here what the risk factors are to get type 2 diabetes, this involves eating an unhealthy diet that's completely the opposite of what I've been writing about above. So, in these studies we're studying primarily people who have done a lot of damage to their bodies for quite some time by eating a bad diet.

What we need instead is a rigorous test with only healthy fit people to see if more or less oil in the context of a super healthy diet is better (healthy = only whole grains, large amounts of vegetables and small amounts of meat). What I've read is that when you measure insulin resistance of healthy people who you put on an extreme low carb diet, you get worse outcomes, but I admit that such tests are not so rigorous, because it's not a natural diet that they could keep on eating permanently and it was also a small study. For me the difference between what I eat and what the average person eats and how I exercise and what the average person physical activity level is, is just too big to take studies done on the average person serious (just consider that I get 50 grams of fibers per day while the average person gets just 15 grams). Count Iblis (talk) 22:45, 21 September 2016 (UTC)

As for the Inuit, they have been isolated long enough that they may have developed the ability to thrive on a diet that would kill the rest of us (and heart disease does appear to have a significant genetic component). They exhibit many other specializations for their environment, such as the ability to withstand lower temperatures, so this would not be surprising. StuRat (talk) 21:12, 21 September 2016 (UTC)

That theory was first refuted in 1928. See Vilhjalmur Stefansson#Low-carbohydrate diet of meat and fish and No-carbohydrate diet#Research on effects of no-carbohydrate diet. --Guy Macon (talk) 21:47, 21 September 2016 (UTC)

I don't see anything in those studies that disproves the idea that the Inuit have adapted to their diet. As for Europeans eating the same diet, those were short-term studies, and cardiovascular disease only shows up after decades, so they aren't relevant there, either. StuRat (talk) 21:57, 21 September 2016 (UTC)

Steffansson followed the extreme low-carb diet for the rest of his adult life, remaining in good health until he died at the age of eighty two. Besides, the burden of proof is on the person making the claim. Where is the science behind the theory that saturated fat is unhealthy? Where is the science showing that inuuit have such an adaptation? In researching this, you might start with Seven Countries Study#Contemporary criticism and Seven Countries Study#Debate since 2000. --Guy Macon (talk) 22:21, 21 September 2016 (UTC)

Regarding the burden of proof and the Inuit, if we had the lone statement that "Inuit's are more able to cope with an all meat, high fat, low carb diet than non-Inuits", then I would agree. However, when you start with the assumption that "Inuits have an all meat, high fat, low carb diet, so non-Inuits can do well on that diet, too", then I feel the burden of proof shifts to whoever makes such a assumption to establish that Inuits and non-Inuits do, in fact, have the same dietary requirements. This is especially true in view of the fact that such prolonged isolation in a radically different environment has led to other obvious adaptations (for example, Inuits tend to have a lower surface-area-to-volume ratio, by having an endomorph somatotype, to limit heat loss).

As for his experiment on himself, a sample size of one is of no statistical value. StuRat (talk) 13:49, 22 September 2016 (UTC)

Freezing, Triple, and Boiling Points of Water

Is it a simple coincidence that the triple and boiling points of water are ⁠1/100⁠ and 100 °C respectively, or is there something deeper behind it ? — 79.118.172.77 (talk) 21:34, 21 September 2016 (UTC)

Celsius, Kelvin, Farenheit. The bit you're talking about only happens in the scale that's designed explicitly to peg the boiling point of water at 100. Would you be fascinated by the fact that water boils at 212°F and has a triple point at 32.01°F? SemanticMantis (talk) 21:47, 21 September 2016 (UTC)

The fact that g ≈ π² m/s² is not a complete coincidence. I am asking if something similar might not be at play here as well with regards to the degree Celsius. — 79.118.172.77 (talk) 22:27, 21 September 2016 (UTC)

The Celsius scale being pegged to water is a thing of purely human convenience and has no bearing on any greater mystery of the universe. As already linked to, you can read about the history of the Celsius scale. Since the trick only works in the Celsius scale, and does NOT work in any other scale, it's plainly obvious it is a coincidental artifact of the Celsius scale; which itself is a scale which has no real connection to the actual physical definition of temperature, and was arbitrarily set up merely to be convenient for people to use. --Jayron32 22:41, 21 September 2016 (UTC)

(edit conflict)In what sense is the approximate value of g not a complete coincidence? The triple point of water is marginally more than a hundredth of a degree above the freezing point that was supposed to be fixed at zero, so I can see no possible "deeper meaning" behind your ⁠1/100⁠. The 100 degrees boiling point was deliberately fixed at a nice round number, of course. Dbfirs 22:45, 21 September 2016 (UTC)

The meter was originally conceived as the length of a pendulum with a half-period of one second. (Later, it was redefined as the forty-millionth part of a terrestrial meridian). Since T ≈ 2π · (L / g)^1/2 , a choice of T = L = 1 and g = π² is the most natural. — 79.118.172.77 (talk) 01:04, 22 September 2016 (UTC)

This New Scientist article reports that the boiling point of water is subject to variables including how quickly it's heated, the shape and nature of the container, and the presence of dissolved solids, including air. 18th-century Swiss geologist and meteorologist Jean-André Deluc apparently carried around a flask of air for about four weeks in order to eliminate dissolved air, via shaking. He then recorded a BP for the air-free water of 112 °C. But the article says nothing about the shape or substance of the container he used to heat the air-free water, nor how quickly he heated it. Which prompts me to ask what is the international standard for determining the BP of water, and what is the relevant international body?

See Vienna Standard Mean Ocean Water. Smurrayinchester 08:19, 22 September 2016 (UTC)

Is there really much truth to this notion of a "pendular metre" though? AIUI, Newton thought of this as a combination of his gravity work and Huygens pendulum work, along with the beginnings of an interest in standards-based metrology. So $g\approx pi^{2}$ is certainly more than coincidence.

Yet this was "Newton's pendular yard", not any precursor to the metre. AIUI it had no influence on ideas for how to define the metre and the pendular concept didn't take off either in France, or in the century after Newton.

Both the yard and metre are of course approximately sized on an arm's length, because that's the human-scaled length unit that's convenient for measuring cloth to clothe that arm, or timber to make houses for them to live in. One might even, after Pennycuick, claim that seconds are the length they are as that too is a human-convenient interval, similar to breathing and the pace of walking. Andy Dingley (talk) 11:36, 22 September 2016 (UTC)

I can't see 60 bpm (once per second) as a walking speed, personally. If I wanted a human-scale time unit, that would be possible as a heartbeat or an average walking pace, I think 76 bpm would be more suitable (even then, it is a slow walk). Double sharp (talk) 15:36, 23 September 2016 (UTC)

30 bpm. Andy Dingley (talk) 15:51, 23 September 2016 (UTC)

Once every two seconds seems even worse... Double sharp (talk) 15:54, 23 September 2016 (UTC)

Yes, fascinated, because Fahrenheit used an arbitrary scale too. He just put 180 degrees between his fixed points, not 100 (not too weird, pre-metrication). But why 32°F? The fascinating part is that he started out with a totally different scale, sensibly beginning at 0°F. The other points were sensibly picked at 32°F (a nice power of two) and 96°F (blood temperature, and a simple three times). Then, he found out that his first measurements weren't terribly accurate. So he had to redefine the scale and its definition, but without changing it. By picking some new fixed points, and the only slightly awkward 32 and 212, he managed to do so.

A similar thing has now happened with the standard kilogram. Rather than the old measure of an arbitrary-sized lump of metal, carefully looked after and yet still shedding atoms, we've now redefined it to a more fundamentally-based standard using crystal structure and other existing standards of length. Yet this has managed to be done without changing anything, by finding another fixed-point value that was within the previous margin of error. Andy Dingley (talk) 11:09, 22 September 2016 (UTC)

No, we haven't. This is planned to happen, but not until 2018. --69.159.61.230 (talk) 06:00, 23 September 2016 (UTC)

2nd postulate

If the second postulate is true then why moving observer with constant velocity / speed notices other moving observers (with constant velocities / speed) with newtonian relativity.

Let we have, stationary observer on an asteroid: OA, astronaut in space ship A = AA and astronaut in space ship B = BB

All observers are at the same location on asteroid initially. Two space ships A and B are launched with speed v1 (say 0.6c) and v2 (0.5c) from an asteroid at time t1 and t2 in the same direction. There is a noticeable distance between the space ships. A pulse is also emitted by OA with velocity “c” in the direction of space ships at time t3. OA can see a pulse, A and B due to their elevation difference. After sometime,

OA observes that a pulse is travelling at “c” ; d = ct

AA observes that a pulse is also traveling at “c” ; da = ct’ Experienced time dilation

BB also sees pulse traveling at “c” ; db = ct" Experienced time dilation

A pulse , A and B are in motion (relative to asteroid e.g.) but BB can observe a pulse is travelling at “c”like OA while the same BB can't observe the v1 of A like OA. Shouldn’t BB observe A is also moving with v1 instead of 0.1c if the second postulate is true for all observers? Can somebody explain why special relativity for “c” and classical physics for speed of A when observed by BB. — Preceding unsigned comment added by 2001:56A:739C:6D00:852F:60EA:A53E:C483 (talk) 22:38, 21 September 2016 (UTC)

Your question seems exceedingly convoluted and hard to follow. Are you basically asking why does an astronaut in a space ship not behave like photons? It seems a bit disingenuous. The 2nd postulate applies to the speed of light in empty space, not "anything going really fast", it's a property of light not a property of "the speed". Vespine (talk) 01:19, 22 September 2016 (UTC)

Can't really follow the question. A "pulse" of what? Also, many of the "paradoxes" are solved by observing the acceleration of your 2 observers are different. --DHeyward (talk) 05:07, 22 September 2016 (UTC)

See Lorentz transformation and Velocity-addition formula. Someguy1221 (talk) 05:11, 22 September 2016 (UTC)

I mean a pulse of light, Ok

Try this way

Let a second pulse of light is fired from another asteroid towards the aforesaid asteroid. The speed of this pulse is also the same for all observers OA, AA and BB. Photon doesn't experience time but from the second pulse (if it can feel) prospective (frame of ref) which observer would hit second pulse first - or - all observers would hit the second pulse of light at the same time. — Preceding unsigned comment added by 162.157.217.155 (talk) 21:38, 22 September 2016 (UTC)

Although photon can't observe anything but it has frequency therefore its life span can be figured out from the # of cycle between the emission and first absorption — Preceding unsigned comment added by 162.157.217.155 (talk) 02:58, 23 September 2016 (UTC)

September 22

What red and green fruit grown in mexico looks like a smooth, oversized avocado?

I went grocery shopping, and was looking for something new to try. In the fresh fruit section they had these red and green fruit, about a liter in volume, somewhat like oversized smooth and less pear-shaped avocados. I haven't a clue what the inside looks like. They were labelled as "Mexico" where the actual name of the item, like "sweet onion" would appear, and I had to ask someone to read the tag on the fruit, which said, "Producto de Mexico"! Anyone have a guess? I can then do a google image search, but otherwise I have no idea where to begin. Thanks. μηδείς (talk) 03:33, 22 September 2016 (UTC)

Sounds like a Papaya to me. Tevildo (talk) 04:09, 22 September 2016 (UTC)

Papayas I've seen are yellow. StuRat (talk) 13:58, 22 September 2016 (UTC)

This is my public apology to all, including StuRat, for my own insufferable behavior here. I should not have carried on to this level. It is unacceptable, and I am sorry. Closing it, though you can still read it, to see my own bad behavior here. Sorry to all, and to StuRat. --Jayron32 14:36, 23 September 2016 (UTC)
The following discussion has been closed. Please do not modify it.
While that may be true, I'm not sure your experience is relevant and thus does not bear mentioning here. What you've seen is of no help to anyone. What people can see for themselves by reading the linked article (which you obviously didn't do, or you'd have seen something different) is the only thing that matters on this page. --Jayron32 13:43, 23 September 2016 (UTC) And do you have any evidence that they are red and green, as the Q asks ? Or are you just here to make a WP:POINT ? I notice you didn't add this until after this Q was resolved (it was a mango) and I challenged your answer as to why there are so many skyscrapers in Chicago [19]. So, it looks like you are out for revenge. StuRat (talk) 13:57, 23 September 2016 (UTC) Yeah, you're right Stu. You totally owned me there. What with your never ever providing a useful reference to anyone ever, and your spouting off personal experiences and half-remembered factoids because we all know, what StuRat has experiences must be The Truth and what StuRat thinks he remembers must be Important for Everyone to Know Now. As usual, every response you have ever given to any question here ever is as useful to anyone as tits on a bull. But you keep being you, Stu. Every time you do, you only continue to make your own ineptitude more and more apparent to all. --Jayron32 14:07, 23 September 2016 (UTC) For half-remembered bullshit answers, we only need to look at your current false info you provided on the US Electoral College here: [20]. I can provide many more such BS answers, from you, if one is not enough. As for my referenced answers, here's one: [21], and I can provide many more, so your statement that I "never ever providing a useful reference to anyone ever" is an outright lie. StuRat (talk) 14:21, 23 September 2016 (UTC) And when someone corrected me, I affirmed my mistake and thanked the person who corrected me. But you'd never do that, Stu, would you. Because you never actually have made a mistake, every pronouncement you have ever made is true because you make it. --Jayron32 14:29, 23 September 2016 (UTC) When I'm actually wrong I am willing to admit it, but often it's just somebody like you bitching just to be obnoxious. The statement that all the papayas I've seen have been yellow is absolutely true, and useful, as papayas was not the correct answer to this Q. And admitting to a mistake once you've been proven wrong (and calling it a "clarification" isn't much of an apology) doesn't seem to stop you from making up bullshit answers again the next time. StuRat (talk) 14:38, 23 September 2016 (UTC)

Mangos? [22] -Modocc (talk) 04:31, 22 September 2016 (UTC)

It's definitely not a papaya based on any images I have seen on google, which are too yellow. It does look like a mango based on google images, and is almost identical to our main image of a mango. I'll assume it's a mango, buy one, and see what I can do with it. I suppose I should have just bought one tonight, but I am busy with other matters, and too distracted to think as clearly as the 25% of US voters who are deplorable, let alone a Bernie supporter.

Thanks. (BTW, I settled on half-ripe bananas, since I knew what the were.) μηδείς (talk) 05:50, 22 September 2016 (UTC)

Resolved

Mangos are absolutely my favorite fruit, if you've never had it before, omg prepare yourself for some magic in your mouth. You have to get one that's ripe and ready to eat. It needs to be a bit soft, press not too had near the top where the stem is, it should "give" a little, like a ripe avocado or a peach I guess, not hard like an apple or pear. Vespine (talk) 06:11, 22 September 2016 (UTC)

I've never found the Mexican mangoes sold in New Zealand very good compared to those from Thailand, India or Australia. (Or those sold in Malaysia generally from Thailand, sometimes locally grown maybe sometimes from elsewhere in Asia.) I don't know if this is also true of those sold in the US. They are better than the Tommy Atkins (mango) often from Peru or Ecuador though. (Although I admit I haven't tried that many, but I've spoken to people with similar experiencse.) Nil Einne (talk) 09:49, 22 September 2016 (UTC)

Agreed, but a poor mango is still damn good fruit.

I think this could be a papaya, or close relative. There are plenty that are eaten green and some that are quite large.

A good use for these larger papayas is as a vegetable in a salad, rather than as fruit. Halve them, deseed them, peel them, and then use a mandoline (or a lot of fine chopping) to cut them into thin strips or julienne. Mix with similar shredded carrot. Then dress with some mix of light (rice) vinegar, a light oil like avocado oil and a bit of chilli, black pepper or maybe citrus juice. Andy Dingley (talk) 11:01, 22 September 2016 (UTC)

Are you quite sure it WASN'T an avocado? There is a wide variation in avocado varieties, in terms of texture and color. this article explains some of the differences. We're used to one basic variety in American supermarkets, the Hass avocado, but there are many varieties, some of which may be grown in Mexico, which look very different. I remember about 20 years ago at a pot luck where a guest from Puerto Rico brought what she called a "Puerto Rican" avocado which was smooth, bright green, and the size and shape of a small watermelon. --Jayron32 11:46, 22 September 2016 (UTC)

Indeed; our list of cultivars at avocado really doesn't do it justice. The volume of one liter is also on the high side, regardless of whether we're talking about mangoes, avocados, papayas or some unholy hybrid between them. Luckily, the seeds of these fruit are very dissimilar; cutting open the sample will make it unambiguous pretty quickly. Matt Deres (talk) 12:09, 22 September 2016 (UTC)

I'm surprised you've never seen a mango before, they are quite common in grocery stores here in Michigan. One warning, when ripe they are quite juicy, so peel it over a bowl in the sink (the bowl is so you can drink most of the juice). I would use a knife to peel it. Also, you will need the knife to separate the flesh from the pit, which looks like a giant white watermelon seed, but had fibers extending into the flesh (a fun trick on little kids is to say you just had a giant watermelon, and show them the mango pit as "proof"). These are good roughage, but do tend to get stuck between the teeth, so plan to floss after. The flavor I would describe as like fruity maple syrup. You can eat it plain or in a fruit salad, or basically anywhere you would use citrus fruit, like mixed with yogurt. StuRat (talk) 13:57, 22 September 2016 (UTC)

I have actually seen the meat of mangoes before, just not the whole unskinned fruit. This fruit is not an avocado, it would have weighed twice as much as it did, and I used to make the guacamole at TGIF. Next time I'm there I'll buy one. The also had ramatans, which thank god were not labelled as philippines from the Philippines. μηδείς (talk) 22:25, 22 September 2016 (UTC)

Would ramatans be rambutans? I've never heard them called that before. @ StuRat you might find this clip helpful, lose no juice and minimise the fibers with this method widely used in the UK. Richard Avery (talk) 06:49, 23 September 2016 (UTC)

Apparently they are the same thing, if you google image them you get the same fruit, although it looks like rambutan is the more common term. There are scary looking, like something out of The Expanse and I had never heard of or seen one until this week. μηδείς (talk) 16:28, 23 September 2016 (UTC)

Prickly pears are plenty scary, too. StuRat (talk) 16:49, 23 September 2016 (UTC)

Prickly pears are generally actually prickly. I guess you could prick yourself on the stalk of a rambutan, but that isn't that different from an apple or both ends of a banana. It's surely difficult to prick yourself on the hairs. Frankly the durian is probably scarier (although you're less likely to get a spike) but people often get too distracted by the smell to notice that. Still walking around a field of trees with ripe durians is best avoided. Recognising what you're seeing is I guess important. Some of the sharper looking Starfruit may look scary if you imagine the spikes are hard. Of course a fruit looking innocous doesn't mean it can't cause such inconviences. I wouldn't say the purple mangosteen looks particularly threatening but the the staining may be more annoying than anything you're likely to get from a rambutan or starfruit. (Although it is also annoying with the skin of the seed sticks to the rambutan flesh.) And since we spoke of smells, not a fruit but the petai smell and taste can be a bit offputting to some but like asparagus, it's probably the after effects that people notice more. Nil Einne (talk) 19:20, 23 September 2016 (UTC)

I've got a potted prickly pear, and my parents have them growing in their back yard. They might look dangerous and for good reason (their spines can pierce leather gloves even when they are grasped with aluminum foil), but the rambutan looks damn spooky, what with its red body and green tentacles. μηδείς (talk) 20:40, 23 September 2016 (UTC)

Differences between electromagnetic field and electromagnetic induction

What are the differences between electromagnetic field and electromagnetic induction? Is electromagnetic induction always being a kind of electromagnetic field?--79.139.159.41 (talk) 09:39, 22 September 2016 (UTC)

Is electromagnetic induction being an electromagnetic work of nucleus of atoms and is electromagnetic field being an electromagnetic work of atoms?--79.139.159.41 (talk) 09:52, 22 September 2016 (UTC)

What are the differences between a gravitational field and a pendulum clock? Induction is a process that uses the field. —Tamfang (talk) 10:18, 22 September 2016 (UTC)

What vectors are always being the main a vectors of electromagnetic induction or vectors of electromagnetic field?--79.139.159.41 (talk) 10:35, 22 September 2016 (UTC)

Is nuclear always doing the work of atom or atom is always doing it self work?--79.139.159.41 (talk) 10:42, 22 September 2016 (UTC)

What are mechanical physics - mechanical models of atom says about that?--79.139.159.41 (talk) 11:02, 22 September 2016 (UTC)

It appears your native language is not English. If you can tell us your native language, we can direct you to another site, likely another version of Wikipedia, in your own language. What is your native language? --Jayron32 11:41, 22 September 2016 (UTC)

It is I’m. I’m interesting is universe being universal and unified, that is could mechanics being determines all?--Alex Sazonov (talk) 12:53, 22 September 2016 (UTC)

Your use of English is not good enough for anyone here to understand what you wish to know. If you tell us what language you speak normally, we can direct you to the correct venue to get your questions answered. What language do you speak? --Jayron32 13:08, 22 September 2016 (UTC)

I'm speak Russian. I want say that the USSR was universalized and unified all humanitarian and all technical knowledge to win in global economic, but the USSR was not won in global economic because the sources of the USSR exhausted.--79.139.159.41 (talk) 13:40, 22 September 2016 (UTC)

On explain of my country the USSR-Russia we could seeing that knowledge and technologies and also capitals are loses to mineral sources.--79.139.159.41 (talk) 14:00, 22 September 2016 (UTC)

Here is a link to the Russian Wikipedia's equivalent of the Reference Desk. If you ask your questions there in your native language, you will likely get better, more prompt responses than you would here. Because frankly, here at English Wikipedia, most of us can't understand you very well. --Jayron32 14:01, 22 September 2016 (UTC)

This was first notice by BenRG but that page is to a merged/deleted page. It links to ru:Википедия:Форум/Вопросы but that page says "Вопросы, не относящиеся к работе над Википедией, будут удалены. Поищите в Википедии, Гугле или Яндексе" which appears to mean something like "Questions not related to work on Wikipedia would be deleted. Search Wikipedia, Google or Yandex." So there appears to be no where on the Russian wikipedia that anyone can get help with these sort of questions. In the case of Alex Sazonov, it's a moot point anyway, they appear to be unwelcome on the Russian wikipedia for writing barely understandable nonsense ru:Обсуждение_участника:Alex_Sazonov and were blocked back in 2014 [23]. My impression is it was the same when they tried speaking in Russian here on en.wikipedia. So I don't think asking in Russian anywhere, even outside ru.wikipedia is going to help if Alex Sazonov speaks the same way. They need to have a far better level of language be it in Russian, English or some other language is they actually want people to help them. Nil Einne (talk) 14:53, 22 September 2016 (UTC)

Is always being matter only a size of available natural mineral sources and nothing more.--Alex Sazonov (talk) 15:56, 22 September 2016 (UTC)

@Alex Sazonov it is unlikely that we can help you further with the two Wikipedia articles[24][25] that you have cited unless you specify a sentence you don't understand. However you can read in most Russian libraries and encyclopedias about the radio pioneer Alexander Popov. Popov built receivers to detect the electromagnetic field that is radiated in all directions by the powerful currents in Lightning strikes. In his receivers, incoming electromagnetic field vibrations induce small current vibrations in an antenna and Coherer device that in turn passes a large current to an Electromagnet that produces physical force to ring a bell, to warn of an approaching storm. The USSR stamp shown says "Inventor of radio, A. S. Popov, 1859-1906. Demonstration of the first radio, 1895" AllBestFaith (talk) 16:01, 22 September 2016 (UTC)

Thank you. Is being interesting did the magnetic fields doing work same as electromagnetic fields?--79.139.159.41 (talk) 16:51, 22 September 2016 (UTC)

So, what a problem had the USSR-Russia if magnetic fields did always doing work same as electromagnetic fields?--79.139.159.41 (talk) 18:00, 22 September 2016 (UTC)

Вы должны прочитать школы книги, что вы понимаете о электромагнетизма. Это обсуждение концы. This discussion ends. AllBestFaith (talk) 19:23, 22 September 2016 (UTC)

Ok, this discussion was closed, but at the end of this discussion, I must to add that optical spectrum of magnetic field is same to optical spectrum of electromagnetic field, that’s why I was had a question what a problem had the USSR-Russia if magnetic fields are same to electromagnetic fields and their laws are same. Thanks to all for this discussion.--Alex Sazonov (talk) 16:09, 23 September 2016 (UTC)

September 23

Child sex abuse statistics

Recently, I volunteered for a program working with children. As part of the required training everyone had to review a set of materials discussing child sex abuse. In those materials were a disturbing set of unreferenced statistics. I'd like to figure out if the statistics presented were accurate / reliable or cherry-picked for dramatic effect. Claims:

1. Only 3% of the perpetrators of child sexual abuse are ever identified and prosecuted.
2. Over a lifetime, a perpetrator who isn't caught can victimize up to 500 children.

So far my google-fu hasn't been able verify or source either claim. I'm sure child sex abuse is underreported, but even so, 3% seems jaw-droppingly low. The 500 victims claim (7 / year for 70 years?) seems like an extreme worst case scenario, if it isn't simply an example of magical thinking. Can anyone help figure out where the claims might have come from and whether they are accurate? This is for a US context, if it helps. Dragons flight (talk) 09:46, 23 September 2016 (UTC)

This [26] says "The belief that child sexual abusers are incorrigible recidivists is also an oversimplication. In reality, the overall re-offense rate for child molesters is lower than that for other criminals." Refs 47-49 there also seem like they may have statistics on victimization counts. This [27] looks to be a very review good article, summarizing many key research studies and statistics. SemanticMantis (talk) 13:05, 23 September 2016 (UTC)

1) You will need to narrowly define "child sex abuse". Public urination, seen by a child, could be included, and men have ended up on the watch list because of it. Consensual sex between an 18 year-old male and a girl just below the age of consent can have the same result. Presumably, a large portion of such cases are never charged, especially if the genders are reversed, as the punishment seems wildly out-of-whack with the crime.

2) Note that any "statistic" containing the words "up to" means there was a single case, no claim beyond that was made. StuRat (talk) 13:20, 23 September 2016 (UTC)

• Regarding the empirical worst-case scenario of the "up to" wording, the lead of Jimmy Savile sexual abuse scandal says:

The Metropolitan Police stated that the total number of alleged victims was 589, of whom 450 alleged abuse by Savile.[4][5]

Loraof (talk) 13:30, 23 September 2016 (UTC)

With this scale of horror, it seems odd to nitpick, but of that 450, "only" 80% were "children or young people" at the time, which is around 360. Smurrayinchester 13:51, 23 September 2016 (UTC)

• Well, the question has basically been answered, but in any case those two stats rise red flags for the concerned statistician. If "3% of the perpetrators (...) are ever identified and prosecuted", one absolutely needs to ask how that number was obtained, since by definition it is a figure that is hard to know (it is possible to estimate it with various methods, but never accept such claims without knowing what degree of credibility the methodology has).

The second one is an "up to" statistic; while it produces a significant emotional impact, it is of little relevance in that case (since that is a big statistical outlier). "Up to" stats can be useful, e.g. you want the bridge to hold "up to X kg", because even if traffic is usually low, you are not satisfied with one collapse per year; but more often than not, they are not the correct measure. That is of course why websites report "up to" X simultaneous visitors, etc. (And of course, a perpetrator "can" rape up to 100,000 victims if starting young enough as a despot, but "can" is the operative word.)

Of course, child abuse is still a big problem, but it does not justify abusing the statistics. I remember than for our driving test we were fed statistics about road deaths, and although some good ones would already have been impressive enough, they were often phrased in misleading way to make an even worse impression. E.g. "x% of road accidents happen on commuting", to tell you to pay attention even on the roads you know well, but of course the relevant number is the deaths by kilometer travelled (or per hour travelled, maybe), which could be either higher or smaller on commuting trips. Tigraan^{Click here to contact me} 16:15, 23 September 2016 (UTC)

The worse stats was "alcohol related car deaths", which could mean anyone in any vehicle involved had been drinking, even a passenger in a car that was hit, versus "alcohol caused", which is the relevant stat. StuRat (talk) 16:18, 23 September 2016 (UTC)

1. The claim rests on a source of "identifying" perpetrators. Such a source might be Child protection authorities who might see a ratio of 33 suspects who merit on-going investigation to every actual prosecution, or it might be a Mental health authority who observes a number of cases considered at risk. In either case the data source would be confidential and unapproachable.

2. The claim contains the weasel wording "up to" 500 that makes the claim almost meaningless, except for its shock value, and almost incontrovertable. Its illusory numerical accuracy leads only to a useless speculation whether exhaustion alone would limit a lifelong (say age 18 to 80) dedicated child molester to victimize (in ways unspecified) a new child on average every 45 days. A source might defend the claim by invoking a concept of collective victimization in a special environment such as a school, Seminary or enslaved area where Child sexual abuse was prevalent. AllBestFaith (talk) 16:49, 23 September 2016 (UTC)

Can being fat ever be healthy?

People always say that being fat is unhealthy. But how fat does a person have to be to receive unflattering comments? Is it ever possible that a person just happens to be born with an undesirable body shape but manages a very balanced diet and maintains regular physical activity with no intention of changing the figure? Can such a fat but able person be possible and healthy? 64.134.39.172 (talk) 19:23, 23 September 2016 (UTC)

The answer may well depend on how fat the person is. If morbidly obese, then probably no, that can't be healthy. However, if just slightly overweight, then it's possible, especially since some extra weight is protective against some diseases that cause sudden weight loss. Not that it prevents the disease itself, mind you, but just that it prevents weight, blood sugar level, etc., from dropping to a dangerously low level. On the other side of the equation, susceptibility to heart disease, diabetes, and other medical problems also has a genetic component, so if someone is lucky enough to be resistant to those conditions, those few extra pounds are unlikely to be a problem.

As far as unflattering comments go, fashion models have set unrealistic expectations, and many of them are underweight, and/or their photos are altered so they look that way. So, a person may very well be normal weight, and yet be criticized for being fat. StuRat (talk) 19:29, 23 September 2016 (UTC)

Sumo wrestlers seem to have a very big figure. Are they considered more unhealthy than the rest of Japan's population? 64.134.39.172 (talk) 19:55, 23 September 2016 (UTC)

If this is a serious question you should be asking your doctor or nutritionist, not for our opinion on the subject. And where did the notion that the rest of Japan's population is unhealthy come from? μηδείς (talk) 20:31, 23 September 2016 (UTC)

From our article: "Sumo wrestlers have a life expectancy between 60 and 65, more than 10 years shorter than the average Japanese male. Many develop diabetes or high blood pressure, and they are prone to heart attacks due to the enormous amount of fat they accumulate." The question was not about the OP's own health, neither did it imply that the Japanese population are unhealthy. Tevildo (talk) 21:15, 23 September 2016 (UTC)

Well, my doctor prefers that I should be slightly overweight rather than at my ideal BMI. So it is horses for courses. Greglocock (talk) 23:17, 23 September 2016 (UTC)

1036 Ganymed

What is the composition, temperature, and pressure at the center of 1036 Ganymed?144.35.45.81 (talk) 20:06, 23 September 2016 (UTC)

It is irregularly shaped. So, it is difficult to pinpoint its center, which makes the composition uncertain as the asteroid is likely inhomogeneous. As to the temperature it likely to be the same as the average surface temperature: ~ 160K. The pressure is probably low: ~$G\rho ^{2}R^{2}\sim 0.15$ bar assuming ρ~1 g/cm³. Ruslik_Zero 20:36, 23 September 2016 (UTC)

The center is where the string points when you try to hang it in a large gravitational field. Now the center of a wok... Sagittarian Milky Way (talk) 22:41, 23 September 2016 (UTC)

WR 102

Currently the article on WR 102 has inconsistency, saying it's in Cygnus and elsewhere that it's in Sagittarius (and is also included in the Sagittarius template). I couldn't google a reliable source on that, but this book says it's in Cygnus. Could someone verify and fix this? Thanks. Brandmeister^talk 22:48, 23 September 2016 (UTC)

An online astronomical object catalog I checked says it's at 17 hours 45 minutes 47.56 seconds and negative 26 degrees 10 minutes 26.9 seconds. Cygnus is very far from there. Sagittarian Milky Way (talk) 23:05, 23 September 2016 (UTC)

Those co-ordinates are very close to the border of Sagittarius and Ophiuchus: we need to double check the co-ordinates given in the sources, and those of the border at present (precession and all that) carefully before making the necessary amendment.

[Update – as of Epoch 2000 (i.e. from Tirion & Sinnot's Sky Atlas 2000.0 2nd Ed 1998) they are just in Sagittarius, so I have corrected the text. I can't comment on Brandmeister's linked book claiming Cygnus, as I can't read Russian.]

However, I notice that these co-ordinates are in the Article cited to its reference 1, a paper which gives them for its Star 2 in Table 5, but I see nothing in that paper to confirm that this star is WR102. I don't suppose that it isn't, but we do perhaps need an explicit confirmation of the identity of the two. {The poster formerly known as 87.81.230.195} 90.202.211.191 (talk) 23:34, 23 September 2016 (UTC)