Wikipedia:Reference desk/Archives/Science/2017 June 16

= June 16 =

Refined grains and food security
I don't know what's so bad or unhealthy about refined grains in the first place. Are refined grains unhealthy because they are too easily absorbable? But then, if they are too absorbable, wouldn't that be a good thing because you can feed more people with the same amount of food? I am not talking about sodas that can cause tooth decay. I'm talking about refined flour-based products, like white bread and white rice. White bread and white rice are said to be "unhealthy", but if you eat them in small portion sizes relative to the amount of vegetables, then are they healthy? Or is it something else that makes refined grains unhealthy? 50.4.236.254 (talk) 02:40, 16 June 2017 (UTC)


 * Refined grains are unhealthy because the human body has evolved over many millions of years to extract nutrients from unrefined carbs containing a large amounts of fibers. If you eat refined grains, the enzymes you have in your gut will extract the carbs too fast, this leads to an insulin spike, glucose levels will then drop as a result, and the body will then react to that by releasing fats into the bloodstream. On the long term this causes health problems. Also, fibers are food for the gut microbes, they break it down and produce short chained fatty acids which the cells in your gut use for energy, and these fats are also involved in many other processes. A diet deficient in fibers has been linked to bowel cancer and cardiovascular disease.


 * The fact that Most of the Tsimané are able to live their entire life without developing any coronary atherosclerosis, should be a warning about how extremely unhealthy our diet is. Count Iblis (talk) 03:09, 16 June 2017 (UTC)


 * You said "a diet deficient in [dietary] fibers". In the OP, I mentioned specifically eating refined grains with vegetables. In other words, a small pile of white rice (refined carbs) for energy and a big pile of mostly vegetables. You are receiving most of your dietary intake of fiber through the vegetables, not the rice. So, the overall diet still contains fiber. In that case, are refined grains healthy and a good way to increase food security (provide more energy with the same quantity of food)? 50.4.236.254 (talk) 03:16, 16 June 2017 (UTC)


 * But you're not going to get the magnesium, zinc and the b-vitamins that are in the unrefined grains, also the carbs now now going to get into your blood faster which leads to the insulin spike. If you eat 250 grams (weighed uncooked) of brown rice as I did today, this still contains 17 grams of fibers, which is the amount contained in 570 grams of vegetables, which happens to be approximately the amount of vegetables I ate today. So, my dinner contained double the amount of fibers thanks to eating brown rice. Now, you could object by saying that you want to eat only a small amount of rice, but then that begs the question of where your calories are going to come from. You could eat more fat, but this contains hardly any nutrients. Or you just want to lose weight, but eventually you have to eat enough calories. And the more physically active you are the more you'll need to eat. Count Iblis (talk) 03:26, 16 June 2017 (UTC)


 * I never said that you would have to eat the same amount of calories. Instead, my intention was that, because refined grains would be more easily absorbable, then you might not have to eat as much as you would with whole grains. You may split the amount for you and your relative/friend. And lots of foods contain magnesium, zinc, and b-vitamins. 50.4.236.254 (talk) 03:36, 16 June 2017 (UTC)


 * What you must consider also is that we don't know everything that's relevant in relation to diet and health. In the 1980s we knew that fibers were important for health but we knew nothing about the fundamental mechanisms involving gut bacteria. It's then very likely that 30 years from now new things will be discovered that we today know little about. The best strategy is then to get you nutrients from as many different food sources as possible. This will make it less likely that some unknown nutrient that will later be found to be relevant, will be missing from your present diet. Count Iblis (talk) 09:14, 16 June 2017 (UTC)


 * As with this. ←Baseball Bugs What's up, Doc? carrots→ 10:30, 16 June 2017 (UTC)


 * Then, there are different individuals. For every single fad diet in the world, there are people who lose, maintain the same, and gain weight. So, personalizing the diet is very important. I recently read a news article that mentions the variations in diets. I think it has to do with different evolutionary backgrounds and specific mutations, as well as changes in the environment and epigenetics. In any case, if you can subsist on refined white rice and vegetables and some meat all the time and stay healthy, then I think that's a good diet for you. But it may be another's worst nightmare. 50.4.236.254 (talk) 11:35, 16 June 2017 (UTC)


 * This has been known, at least observationally, for centuries. Hence "Jack Sprat". ←Baseball Bugs What's up, Doc? carrots→ 12:42, 16 June 2017 (UTC)


 * That's an artifact of eating a diet that's extremely far away from what's optimal. Our diet is full of empty calories due to eating fats, allowing us to eat far smaller volumes of whole grain carbs. We also eat far smaller volumes of fruits and vegetables. As a result we cannot get the essential amino-acids from vegetables anymore, but meat and dairy products then come to the rescue. But meat = empty proteins, and from dairy products we only get proteins and some minerals like calcium that are now missing from vegetables, so we will still get a large shortage of fibers and phytonutrients. Now, having moved so far away from the physiologically normal diet, many of us will be close to a local optimum (which will be far worse than the global optimum). But what's a local optimum for me may differ from your local optimum, because the damage done by the various components of the unhealthy diet will be different for different people. Count Iblis (talk) 01:28, 17 June 2017 (UTC)


 * What you say is interesting. But it's entirely unsourced. Do you have any credible sources that back you up? Human nutrition is a hot topic. Many "experts" give their own opinions of what makes a healthy diet. In your case, I'd like to know where you get the idea of having a global or local optimum. A person with lactose intolerance, milk allergy, wheat allergy, gluten insensitivity, or celiac disease would benefit from a dairy-free or gluten-free diet. 50.4.236.254 (talk) 13:13, 17 June 2017 (UTC)


 * There is evidence for that in some special cases. Take e.g. the Yanomamo Indians who in their natural habitat get just 50 milligrams of salt per day. As pointed out here, they don't get heart disease, and that's then due to lifestyle not genetics, because when they emigrate to civilization then they get heart disease and at quite young ages. So, genetics puts them at a disadvantage for heart disease. Now, as pointed out in the article, when eating a normal western diet it's normal that blood pressure rises with age but the Yanomamo Indians in their natural habitat don't have this blood pressure rise as a function of age. And it's not just that genetics isn't a relevant factor we can strike out stress too, because the lives of the Yanomamo in the jungle is extremely stressful. So, while reaching the local optimum near the Western lifestyle likely does require getting rid of stress as much as possible, that's not true for the global optimum when you stick to a natural lifestyle where your salt intake will be about 100 times less than what's considered to be normal in the West. Count Iblis (talk) 22:33, 18 June 2017 (UTC)


 * I believe there's an incorrect assumption in this Q, that more calories are absorbed from refined grains than unrefined. That's not the case, it just takes longer to absorb the calories from the unrefined grains, giving your body time to handle the glucose properly.  Therefore, your best bet, if you were forced to eat refined grains only, would be to eat them a bit at a time, so as to not create a sugar spike and then insulin spike and subsequent sugar crash.  Eating them with lots of veggies would also help.  Of course, it's still not as healthy as eating whole grains, due to the lack of micronutrients in refined grains.


 * Now, when dealing with starving people in Africa, say, the logic is a bit different. White flour may be better there, in that it doesn't spoil as quickly, and diabetes isn't much of a concern for them, relative to famine.  Of course, whole grains are still healthier, even there, but if they rot in transit that negates this advantage. StuRat (talk) 13:37, 16 June 2017 (UTC)

Spermaceti organ weight
How heavy is a Spermaceti organ? Many thanks. Anna Frodesiak (talk) 03:37, 16 June 2017 (UTC)

If anyone can find this info, please add it to Spermaceti organ and Sperm oil. The latter only talks about percentages and temperatures, but not how much a whale has in its head. Anna Frodesiak (talk) 07:35, 16 June 2017 (UTC)


 * As a first approximation only: most (shall we guess at 90%?) of the weight of the organ is going to comprise the Sperm oil contained within its outer case; Sperm whale tells us that the organ "can hold within it up to 1,900 litres of spermaceti", while Sperm oil tells us that the oil's specific gravity is 0.884 at 15.6 °C. This would give us a maximum oil weight of 0.884 x 1,900 = 1,680kg, suggesting (per our 90% guess) that the spermaceti organ may weigh up to 1,867kg.
 * Factors to consider:
 * (1) sperm whales vary in size both individually and by sex, and the "up to 1,900 litres" presumably implies "from the largest males", so our guesstimate is going to be around the maximum, not the average.
 * (2) the tissue spermaceti contains the sperm oil but is not identical to it, so the 1,900 litres of spermaceti may have a slightly different specific gravity to the oil.
 * (3) Sperm oil is also contained in the whale's "junk" or melon, which is a different organ, and quoted oil yields may (or may not) combine the two.
 * (4) the initial 90% guess may be off.
 * Doubtless others can refine this approximation, but specific references would be necessary to add any figures to articles, as the above probably constitutes Original Research. {The poster formerly known as 87.81.230.195} 2.217.208.38 (talk) 13:06, 16 June 2017 (UTC)
 * The sourced article says more clearly "The organ is filled in life with as much as 1900 liters of a liquid", making it clear that this is for the organ, not the junk/melon. SemanticMantis (talk) 22:02, 16 June 2017 (UTC)

Thank you, folks. I've added the content to three articles. Please modify or revert as you see fit. 

Best,

Anna Frodesiak (talk) 06:56, 17 June 2017 (UTC)

London tower block fire engineering
Are there any articles which go a bit more into the engineering behind the London tower block fire at Grenfell, beyond what the mainstream media are reporting? 82.132.224.179 (talk) 07:05, 16 June 2017 (UTC)


 * I was initially skeptical that British fire safety authorities would have allowed a high-rise apartment building which was of fire-proof concrete construction to be clad for appearance purposes with flammable cladding, but a Guardian article says that the cladding was aluminum ("aluminium") foil backed with polyethylene, with an airgap between the flammable polyethylene and the concrete surface which would have allowed a chimney effect to spread the flames easily from one story to the higher one.  The cladding cost 1/12 less than similar fire-resistant cladding from the same supplier.  Germany does not allow the use of such flammable cladding  on highrise apartment buildings. See also another Guardian article on the cladding hazard. Recently in the US an interstate highway bridge was destroyed by a stack of high density polyethylene pipe stored under it burning. This indifference to fire safety in highrises is surprising. The low-rise council housing I have seen in the UK seemed to be of masonry on the outside, as opposed to cheap low-rise US construction which is often flammable vinyl siding. Edison (talk) 13:19, 16 June 2017 (UTC)
 * skyscrapercity forum is blacklisted here on WP (it was being massively used as a source for articles, in violation of WP:RS), but the skyscraper affectionos there will no doubt be doing a complete dissection of this disaster. Google them. "Cladding fire" skyscraper disasters have happened before. We had one here in Australia. BUT here the building had sprinklers, and everyone got out alive. Dubai, on the other hand, has had similar high-rise horrors. Eliyohub (talk)|
 * Which Dubai similar horror are you referring to? They have had several but AFAIK, they've generally been similar to the Australian ones with few, if any, deaths. The Address Downtown Dubai had I believe on death from a heart attack. The Marina Torch for example I believe had no fatalities  as to Tamweel Tower  . Fortune Towers did kill 4 but it was under construction meaning the fire safety systems may not have been completely in place and well we all know how foreign workers are treated in Dubai or a lot of the Middle East (sadly not much better in Malaysia) . Besides as horrific as that was, even ignoring the underconstruction bit it doesn't seem similar to Grenfell considering that is already at 17 and there's unfortunately strong indications it's likely to rise significantly. Villaggio Mall was rather horrific with 19 deaths but I don't believe it was a cladding or high-rise fire, many of the deaths were at a day-care centre/nursery/officially entertainment centre.   If there is some high-rise cladding fire in Dubai I'm missing which was similar to Grenfell rather than similar to the Melbourne one in terms of how "horrific", it's a little weird that these similar horror fires aren't mentioned here  (from just now) or  (from 2016). Nil Einne (talk) 18:32, 16 June 2017 (UTC)
 * I stand corrected. I'd naively looked at those horrible photos of burnt skyscrapers, and assumed horrible scenes within. You are correct, the Dubai fires have not caused many deaths. Eliyohub (talk) 05:42, 17 June 2017 (UTC)

how does this circuit work?
this is an op-amp MW radio. I don't quite get some things though: Thank you everyone in advance! 80.171.106.146 (talk) 10:33, 16 June 2017 (UTC)
 * the first stage is wired for an AC gain of about 1300 ((200k+120R+Xc)/(120R+Xc)). correct? if so, wouldn't that require a monstrous gain-bandwidth (in the gigahertzs) for it to work as intended? (the Soviet 157UD2 is, from cursory googling, just a garden-variety opamp)
 * do the caps in the voltage-doubler detector constitute capacitive loading? is it bad?
 * what is the advantage of picking up the RF from a second coupling coil?
 * this circuit aside, what is roughly the amplifier input impedance a loopstick antenna should ideally work into?
 * I cannot see the picture. Can you find it or post it somewhere else or check your link? However an RF gain of 1300 is very likely to lead to instability if more of the output gets to the input through another route. Graeme Bartlett (talk) 11:24, 16 June 2017 (UTC)


 * I cannot comment on the rest, but a monstrous gain-bandwidth (in the gigahertzs) is nothing unheard of. For instance, here is an amplifier with a 7GHz gain-bandwidth (gain 2k, BW 3.5MHz), and it is hardly exceptional among the others from the same provider. Tigraan Click here to contact me 11:34, 16 June 2017 (UTC)
 * OK I can see the picture now. at http://zpostbox.ru/r1_e.htm The data sheet suggests to me that the gain is between 10 and 40 times at 1MHz. The "voltage doubler" is a rectifier to convert the RF to AF. So the 2200 cap bleeds off some of the power from the output of the opamp to the rectifier, and the 10H (is that nanofarads?) capacitor filters the RF from the AF. The AF is conducted to the next stage via the 0.1MK capacitor. They add some small load to the opamp, but you can expect it to be able to take it. A separate secondary coil can place a much lighter and adjustable load on the RF tuner. It would also reduce the effect of the voltage variations on the tuning. Read the Loop antenna article where you will see that radiation resistance is very low, but that the required matching impedance is high. The load that you place on the tuning coil will determine the Q factor and the bandwidth recevied. You will want this to be about 10 kHz or so, and at 500 kHz that means that you do not want the Q to be over 50, but at 1500 kHz a Q of 150 is better. If you make the Q on the tuning coil too high you will get a muffled sounding output from your radio. Graeme Bartlett (talk) 11:55, 16 June 2017 (UTC)
 * From a typical capacitor value for the tuner (?200pF) the impedance will be around 1kΩ, so you should have that sort of figure. For these sort of frequencies the received noise is the limiting factor, rather than the device noise. Graeme Bartlett (talk) 12:25, 16 June 2017 (UTC)
 * @Graeme Bartlett Your link http://zpostbox.ru/r1_e.htm shows 39 circuits of which one titled 33. MW radio based on op-amps. is blank. What circuit are you looking at? I find the picture now. At MW frequencies 500 - 1600 kHz the first op-amp is incapable of any significant voltage gain but it helps as a buffer to minimise loading of the ferrite rod antenna. The combination of opamp and detector diodes may not perform much better than some simple Crystal radios. The second opamp is an audio amplifier with gain of 34 dB (47.6x) at 1 kHz and it has a small output capacitor that suggests use of a high impedance headphone. There is no volume control. The circuit may work but not impressively well, giving a weak tinny sound and unable to separate strong local transmitters. See the good responses by Graeme Bartlett. Blooteuth (talk) 00:00, 17 June 2017 (UTC)
 * That was the circuit at 33. I had to refresh to avoid an error too. Adding to my Q factor, if the Q is lower it will receive adjacent stations together and a weak signal will be overcome by a nearby strong one. Graeme Bartlett (talk) 01:01, 17 June 2017 (UTC)

Quantum communications II
I just posted on the subject. Today in the WSJ I found an article about a Chinese "achievement." I cannot provide a link but the article said that the experiment was published in the latest issue of Science. There is a good link to the Gardian.

This is the description as I understood it. They had a pair of ground based quantum transmitter/receiver. The distance between the transmitter and receiver on the ground was 1,200 miles or so. They also had a satellite that combined both, the transmitter and receiver. It was an experiment of sending entangled photons from the land transmitter to the satellite and from the satellite to the land receiver. They probably transmitted polarized photons. The experiment was apparently successful. The articles quotes various scientists praising the achievement but it also says that the Chinese are years away from achieving their goal: creating a secure network.

This is what BBC says about it.

I would appreciate any comments. --AboutFace 22 (talk) 14:48, 16 June 2017 (UTC)


 * This is not "quantum cyrptography" in the sense that entangled pairs of (whatever you want) particles are being used. This is not FTL communication. This is nothing more than sending quickly changing polarized light from one place to another. "Quantum" comes in because of quantum uncertainty. Specifically, if you measure the polarization of light, you change the polarization of the light. So, it makes it very hard to intercept the stream of light without affecting it. The goal is to make eavesdropping very hard to do. It is a very good achievement. Previous experiments have been limited. First, the light had to be sent over a photooptic cable. Then, open air transmission was over very short distances. Going long distances required a lot more light - which means that an eavesdropper can siphon off a fraction of the light to "decrypt" without you noticing. What they are currently doing is going for long distances with a lot of light and will later work on reducing the light to a goal of just one stream of photons. 209.149.113.5 (talk) 15:48, 16 June 2017 (UTC)


 * Wouldn't such long distances either require a lot of photons or transmitting through a vacuum ? StuRat (talk) 16:40, 16 June 2017 (UTC)


 * Yes. That is why this is not considered successful quantum encryption yet. They are using way too many photons for that. But, they are on the path to using less and less photons and, eventually, they will have communication that will be very hard to secretly snoop on. 209.149.113.5 (talk) 17:12, 20 June 2017 (UTC)

Can non-treated diabetes cause neurological damage?
Can non-treated diabetes cause substantial neurological damage in a short period of time like in the case of Otto Warmbier? --Hofhof (talk) 17:36, 16 June 2017 (UTC)


 * In short, no. Diabetic encephalopathies are late (and relatively rare) complications of diabetes. The MRI abnormalities described by Otto Warmbier's American physicians ("extensive loss of brain tissue") are more likely the result of a period of anoxia. I have heard no media reports that Otto Warmbier is diabetic. - Nunh-huh 18:38, 16 June 2017 (UTC)


 * He was diabetic, here is they mention it: . Left untreated, wouldn't he fall into a diabetic coma? Couldn't this cause brain damage, maybe indirectly due to a fall? --Hofhof (talk) 18:51, 16 June 2017 (UTC)
 * I think you've mis-read that article; it says that Kenneth Bae is diabetic, not that Otto Warmbier is. DKA (diabetic ketoacidosis) causes neurological dysfunction and even death, but it doesn't cause an "extensive loss of brain tissue." - Nunh-huh 19:40, 16 June 2017 (UTC)


 * Yes to the title Q, see diabetic neuropathy. However, still no to the text of your Q, as noted above. StuRat (talk) 20:13, 16 June 2017 (UTC)


 * I have absolutely no proof for this, but the obvious explanation that comes into my mind is what the U.S. has established is the perfectly legitimate practice of water boarding foreigners to get them to explain what they were up to. Occasionally such things lead to tragic and unforseeable accidents. Wnt (talk) 14:32, 17 June 2017 (UTC)
 * See Waterboarding. Blooteuth (talk) 12:21, 18 June 2017 (UTC)
 * If it happens "occasionally" then it's foreseeable. - Nunh-huh 08:22, 20 June 2017 (UTC)