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May 1

Why don't low-carbohydrate diets cure diabetes?

Low-carbohydrate diets have drawn a lot of criticism over the years. I know that large amounts of protein, for instance, might be hard on a diabetic's kidneys, and a high intake of saturated fat can raise cholesterol and LDL levels, further increasing the risk of heart disease in the high-risk diabetic population. I wouldn't recommend such a diet, but there's something that I don't understand: Why doesn't a low-carbohydrate diet eliminate the body's need for insulin-meditated glucose uptake? I know that the body would need to convert some of the protein in such a diet to glucose in order to supply the brain with energy (only a portion of its needs can be met by ketones), but the muscles and fat cells - which require insulin for glucose uptake - don't have to run on glucose. Why is that glucose levels don't drop dramatically on a low-carbohydrate diet? How much glucose can the body produce from the protein in a low-carbohydrate diet? I've read that the body tries to maintain homeostasis, so even after days of total starvation - a state in which the body runs on its own fat and protein reserves - glucose levels don't drop that much below normal. Does that have something to do with it?

I found a study in which subjects ate just 21 grams of carbohydrate per day. Their HbA1c improved, but it was still elevated at 6.8%.174.131.63.119 (talk) 01:05, 1 May 2016 (UTC)

Which diabetes? Diabetes mellitus type 1 is characterized by a non-functioning pancreas, specifically the loss of function of the beta cells. It has no connection to dietary intake, in the sense that it is neither caused by, nor particularly fixed by, changes to one's diet. Diabetes mellitus type 2 is a different beast entirely, it isn't about problems on the insulin production end, it's a problem with insulin resistance. As noted in Wikipedia's article, type 2 diabetes can be managed by dietary controls in ways that type 1 diabetes cannot. --Jayron32 01:16, 1 May 2016 (UTC)

Type 2 diabetes ("diabesity") can be helped by a low carb diet, but note that diabetics also need to prevent low blood sugar levels, so low glycemic index foods, which don't cause the sugar spike and then collapse, are a better choice than just eliminating carbs. StuRat (talk) 05:07, 1 May 2016 (UTC)

One reason, I believe, is that the liver produces glucose through gluconeogenesis even if you don't consume any carbohydrates. And, diabetics usually have elevated levels of gluconeogenesis. One of the most widely-used drugs for treating type 2 diabetes, metformin, works in part by inhibiting gluconeogenesis. --71.110.8.102 (talk) 09:38, 1 May 2016 (UTC)

Its not carbs specifically that raise blood glucose, its the glycemic load of the carbs and other foods that do that. So if you decrease your glycemic load in meals, you are likeky to reduce your blood glucose values after eating.--178.103.251.111 (talk) 15:30, 1 May 2016 (UTC)

A small study has shown that a general low calorie diet can put type 2 diabetes into remission, although the long term prognosis isn't known yet.[1] Richerman (talk) 16:55, 1 May 2016 (UTC)

That study indicates its the loss of weight/fat due to restriced calories, not a low calorie diet as such. So one might expect same results by other weight/fat loss methods.--178.103.251.111 (talk) 18:06, 1 May 2016 (UTC)

However, other studies have shown that those who have had bariatric surgery show an immediate improvement in management of diabetes, corresponding to the reduction of calories, before any significant weight is lost. StuRat (talk) 04:16, 2 May 2016 (UTC)

Erm.... Bariatric surgery IS weight loss surgery Stu!! So after the surgery, you have lost weight.--178.103.251.111 (talk) 16:47, 2 May 2016 (UTC)

You must be thinking of liposuction, where they physically remove fat. I am talking about procedures where they limit the capacity of the stomach, by inserting a balloon, putting a band around it to limit expansion, or bypass most of it surgically. Those don't cause weight loss during the surgery, only after. StuRat (talk) 00:29, 3 May 2016 (UTC)

Yes you are right. My mistake. Didnt read article properly.--178.103.251.111 (talk) 17:07, 3 May 2016 (UTC)

Before insulin was discovered, diabetes type 1 patients were treated with a low-carbohydrate diet. It didn't cure the patients but it extended their lives with a year or so. Severe starvation diets were also tried with no better results [2]. Sjö (talk) 04:52, 2 May 2016 (UTC)

Energy Conservation in Sulfur Oxidizers

I was curious if any of you knew anything about the sulfur-oxidizing bacteria. I have several sources saying that if the bacteria use the enzyme sulfur dioxygenase to oxidize elemental sulfur to sulfite, they conserve no energy from the reaction. It is clear that energy is conserved from the oxidation of sulfite to sulfate, which is catalyzed by sulfite oxidase, but scientists don't know if energy is conserved from the first reaction. I came across a book that said there was evidence that even aerobic sulfur bacteria conserve energy from the oxidation of elemental sulfur to sulfite, and that they use an enzyme other than sulfur dioxygenase. I was wondering what that enzyme might be. I didn't know if anyone here could tell me anything about this.174.131.63.119 (talk) 01:27, 1 May 2016 (UTC)

Did you read the obvious article Sulfate-reducing bacteria and perhaps Sulfur-reducing bacteria (both linked from Sulfur bacteria) and associated refs? Nil Einne (talk) 17:39, 1 May 2016 (UTC)

Sorry for the useless answer. I was a bit tired at the time and didn't read the question properly. Nil Einne (talk) 12:50, 2 May 2016 (UTC)

The review [3] (2014) should be more helpful. It says "Extensive research has been done with chemolithotrophs that use sulfur oxidation for energy or with some phototrophic bacteria that extract electrons from reduced sulfur for photosynthesis ... SDO activities were first identified for chemolithotrophs, but the enzymes have not been purified, and the genes are unknown. SDOs are known as GSH-dependent sulfur dioxygenases because GSH spontaneously reacts with sulfur to produce GSSH, which is oxidized by the enzymes to sulfite and GSH." The enzymes are present in other organisms, like humans, for purposes of detoxification, and they know more about those enzymes; but I gather they're not really optimized for energy production. Wnt (talk) 18:09, 1 May 2016 (UTC)

Great article! Thank you!174.131.42.176 (talk) 00:50, 2 May 2016 (UTC)

Cancer bringing partners back together

20 years ago, the wife of my cousin left him. They had been married quite a while and their children had grown up. 8 years ago he developed cancer. His wife returned and cared for him while he was ill, took him on daily trips to hospital for chemotherapy, x-rays, etc. He is now cancer free 7 years+ and they are still living together. I have a friend with a not dissimilar experience. I suspect it may be not at all uncommon for major negative experiences to restore a marriage or relationship, and for others, help destroy it.

Have any studies been done on the effect of cancer on marriage stability, positive or negative? Where would I find them? 60.228.85.120 (talk) 02:01, 1 May 2016 (UTC)

You might try a support organization for those with cancer, their families, and friends. StuRat (talk) 05:11, 1 May 2016 (UTC)

This question is better placed on the Humanities page methinks.--178.103.251.111 (talk) 15:50, 1 May 2016 (UTC)

Yes, lots of studies. I'd add "psychology" or "psychological" to your search terms - the medical literature tends to focus on the reverse question (how the spousal situation affects the cancer) so you need to find the psychological literature. Try this search as a starting point. 184.147.128.57 (talk) 19:38, 1 May 2016 (UTC)

Question regarding Physics

Why do every moving body (most of the time- round objects) in air or vaccum rotate about its axis in a fixed speed? For example: If we throw a ball in air then we will see that the ball is moving with some rotations. In the space also same thing happens. But how and why? sahil shrestha (talk) 02:27, 1 May 2016 (UTC)

@Sahil shrestha: Please remember to post your questions at the bottom of the page. What you describe will only occur if the object is given some initial non-zero angular momentum. As long as no net torque is applied after the object is thrown, that angular momentum is conserved and the object keeps spinning.--Jasper Deng (talk) 06:21, 1 May 2016 (UTC)

@Jasper Deng: Huh! Bottom of the page? But I just ask and post the question by clicking on 'Ready? Ask a new question' button. I really don't know how to post it on the top or bottom of the page. When I ask a question it appears on the top in the beginning and after sometime when I look up for answer it appears in the bottom of the pagr automatically.Can you help me to do so then? sahil shrestha (talk) 08:20, 1 May 2016 (UTC)

@Sahil shrestha: Make sure that you are filling out the resulting form exactly as it says (you should not have to type == at any point). I am also not sure whether it works on mobile.-Jasper Deng (talk) 08:28, 1 May 2016 (UTC)

@Sahil shrestha:I confirm that your posting works and you even used indent and signing correctly. There is a simple answer to your question here in Simple Wikipedia. A ball rotates, as you said, at a fixed speed in a vacuum. But in air a ball's rotation slows down very slightly because of friction with the air, and a rotating ice skater has a way to change her speed of rotation (explained in the article). AllBestFaith (talk) 10:55, 1 May 2016 (UTC)

Tangential syntax test: simple:Angular momentum —Tamfang (talk) 09:39, 4 May 2016 (UTC)

I just tried putting == in both the subject and text of a test posting, and the software handled it admirably. [4] It must be something else. Wnt (talk) 11:29, 1 May 2016 (UTC)

The problem is something Jasper Deng suggested. Sahil shrestha is using the mobile website to edit. (You can see this from their contrib tags Special:Contributions/Sahil shrestha.) The "ask a question" button which uses the mw:Extension:InputBox function doesn't work on the mobile site. You can check it for yourself here [5]. The section=new Query string doesn't seem to be intepreted by the mobile editor. There is a way to add a new section to a talk page with the mobile editor, but I'm not sure how to carry this over to a non talk page. Some other pages use a forced link to the non mobile site which gets around this problem. (I'm not sure if it's the reason.) Nil Einne (talk) 16:02, 2 May 2016 (UTC)

@Sahil shrestha: If you really used the "Ask a new question" button, you might have found a bug in the Wikipedia software. Wikipedia gets frequent updates, and I've gotten a related bug myself when I tried to edit a new section at Meta:Wikipedia_to_the_Moon/Discussion. (I thought the bug was only on Meta, and because of their crazy translation templates) Hitting the "new question" button opens a URL like this: https://en.wikipedia.org/w/index.php?action=edit&preload=&editintro=&preloadtitle=&section=new&title=Wikipedia%3AReference+desk%2FScience&create=Ready%3F+Ask+a+new+question%21 Wikipedia generates that URL on its own, and it interprets "section=new" on its own. You couldn't even chop off the end of the URL by accident, because the page to be edited comes after the "section=new". Next time you ask a question, please check to make sure that's the URL you see you are editing. We'll continue debugging from there. Wnt (talk) 11:24, 1 May 2016 (UTC)

When you toss a ball, unless you exert a force on it right in line with it's center of gravity, it will introduce a torque which causes the ball to rotate. While air resistance will eventually stop it from rotating in air, it will likely take far longer than the ball will be in the air. In space, with no air resistance, it could keep rotating for billions of years. By contrast, a ball floating in water won't rotate for long, due to the much higher resistance to movement exerted by water. StuRat (talk) 15:03, 1 May 2016 (UTC)

@Sahil shrestha: Conservation of angular momentum is a consequence of inertia, which is a consequence of relativity. If you have two unconnected masses in empty space that are moving relative to one another, they each keep moving at the same rate. But if you tie them together so they cannot move apart, then each pulls on the other with centripetal force. The rule by which centripetal force works is that they change their motion to go around and around in circles, but keep the same speed (assuming a constant length cord). That is, incidentally, the only way to conserve energy. A spinning top is like those two connected masses in space, only there are more particles all around the top, each trying to fly out in a straight line but being pulled constantly in toward the center. Wnt (talk) 00:30, 2 May 2016 (UTC)

It is indeed possible to toss a ball that does not rotate. See knuckleball.    → Michael J Ⓣ Ⓒ Ⓜ 15:47, 2 May 2016 (UTC)

Sufficiently symmetric objects (such as spheres or cubes) rotate at a constant rate because of conservation of energy: if they rotated faster/slower, the total kinetic energy of the moving parts would be higher/lower.

Less symmetric rigid objects don't rotate at a fixed rate or around a fixed axis in general, even in a frictionless vacuum. Here's an example (a spinning book on what I assume is the ISS). As the rotational axis changes, the rotational speed also changes, again because of conservation of energy: when rotating parts are nearer to/farther from the axis of rotation, they have less/more kinetic energy at a given rotational speed, so the rotation has to speed up/slow down to conserve energy.

The angular momentum vector of a free-spinning object in vacuum never changes, but the axis of rotation isn't always parallel to the angular momentum. -- BenRG (talk) 00:39, 3 May 2016 (UTC)

WDM

Is it true that WDM can hide inside planets and keep them warm?--178.103.251.111 (talk) 18:12, 1 May 2016 (UTC)

Warm dark matter or warm dense matter? Tevildo (talk) 18:53, 1 May 2016 (UTC)

Dark--178.103.251.111 (talk) 19:54, 1 May 2016 (UTC)

No, due to lack of interaction with normal matter, and their high energy, WDM particles would not be confined to a planet. If there was enough of it, perhaps it could warm a planet, but would also warm a star even more in this situation. You may also wish to read http://arxiv.org/abs/0808.2823 and http://arxiv.org/abs/0903.4879 with Stephen L. Adler as the author promoting these ideas. Graeme Bartlett (talk) 22:23, 1 May 2016 (UTC)

OK. So it could permeate a planet?--178.103.251.111 (talk) 22:41, 1 May 2016 (UTC)

The dark matter making up the Milky Way is moving at less than 270 km/sec. But to hang around the Earth it would have to be under the escape velocity of Earth. Anyway dark matter if it is in small enough pieces would easily permeate a planet. If however it is in bigger pieces, eg 1 gram, up to millions of tons, it may actually interact quite strongly with planets, say if it was hydrogen snowflakes, or meteors. Even if it were pieces of neutron star material or mini black holes it could punch its way through Earth, but deposit energy and cause damage. Graeme Bartlett (talk) 03:29, 2 May 2016 (UTC)

So what is the likleyhood of WDM permeating OUR solar system?--178.103.251.111 (talk) 23:01, 2 May 2016 (UTC)

If WDM exists, and is the cause of the mass of dark matter, then it will be in the solar system, but since we do not know if dark matter is WDM or not then we cannot say if it is in the Solar System or not. Personally I think that the chance is 0% because I do not think it exists, but opinions count for nothing here. You should just be asking "Does warm dark matter exist?". The answer to that is that no one knows, and that assigning probabilities is almost impossible. Graeme Bartlett (talk) 08:36, 3 May 2016 (UTC)

To take a different tack on the question, our current theories appear to explain Earth's heat without involving dark matter. So either there's some overlooked flaw in those theories, or dark matter makes no noticeable contribution to Earth's heat, which means it likely doesn't for other planets either. As other respondents touched on, the most popular hypotheses about dark matter predict that it interacts with "ordinary matter"—what planets and stars are made of—extremely weakly, which means it would do nothing to affect planets' internal heat. Since this is in fact what we observe, we're probably on the right track. --71.110.8.102 (talk) 21:16, 3 May 2016 (UTC)

How large of an animal could exist?

How large could they get at Earth gravity? How close could we get to sandworms (Dune)? Sagittarian Milky Way (talk) 20:39, 1 May 2016 (UTC)

You may want to specify land animals, there is a considerable difference as to how large an animal could be if it supporting its own weight on land vs. being supported in the water. See Square-cube law#Biomechanics for some of the limiting factors.Naraht (talk) 20:43, 1 May 2016 (UTC)

Some land dinosaurs were pretty damn big. Almost as heavy as blue whales. And if a blue whale grew bigger maybe the pressure differential with depth would bother it. If the whale grew longer it might not have enough mouth area to volume to eat. If it grew wider it would be harder to streamline I would think. And if it ate above the bottom of the food chain instead of things like plankton or seaweed it might have difficulty finding enough food (the sperm whale, pliosaur and tyrannosaur-type dinosaurs being smaller than their plant-eating brethren). So I'm not sure it's obvious there's a big difference between land and sea. Sagittarian Milky Way (talk) 23:21, 1 May 2016 (UTC)

Almost as heavy? According to dinosaur size, the largest titanosaurs were roughly 70 to 90 tonnes, which is a very impressive ~10-12 elephants. By contrast, blue whales run more 170 tonnes, which is roughly double the largest known dinosaur. Dragons flight (talk) 11:32, 2 May 2016 (UTC)

Biology is the science of the possible, but physics is the science of the impossible. You can look at any large living or extinct organism and propose that evolution could design something better. It simply becomes unlikely as large organisms need large food sources, in addition to good engineering, but that is simply a question of what probability you accept. But it is hard to picture a true Dune sandworm based simply on the energy needed to push apart the sand vs. any plausible energy source in the sand. If someone can design an artificial sandworm, we can postulate a real one - though of course even then, postulating a stout is not the same as tasting it. I doubt they can, though... at least, not without relaxing the definition of sand to include a certain amount of fissionable material. (The sand could also be a conventional fuel, but then, why isn't it on fire already?)

If you want a more sciency prediction of maximum mass, you can go to the article that fortunately was cited in insular dwarfism here [6] (freely available), which gives a graph of herbivore or carnivore size relative to island area. I note however that it looks like you could extrapolate it to roughly 100,000 kg for a land herbivore by that logic, whereas Brontosaurus (isn't it lovely to use that term again without being tsk-tsked!) is only around 15,000 kg according to that article. Of course, the continents break up the existing land mass, so that wouldn't be valid ... question is, if all the continents were together, could you get 100,000 kg? Maybe, though it didn't happen last time that we know of. Our blue whales are 173,000 tons, and I suppose that is roughly where the line should come out for the ocean, which is all one mass, if you guesstimate it on that graph. (Funny part is, according to this logic, blue whales are larger because the oceans are bigger, not because the water supports their skeleton! I wonder if I can confirm that...) Anyway, this logic might be put to the test on Super-Earths, where engineering requirements are much more demanding, but the land mass is truly colossal. Wnt (talk) 00:15, 2 May 2016 (UTC)

Argentinosaurus approaches 100 tons and lived in South America. The parts of land bodies that cannot be in the range for a species should be considered, too. For continents with multiple biomes this could be considerable. Sagittarian Milky Way (talk) 08:49, 2 May 2016 (UTC)

OMG. I knew the titanosaurs were a trifle bigger, but I didn't realize it was such a difference. But I guess that's what taking the cube of the length will do. I should have looked up Dinosaur size. Wnt (talk) 13:14, 2 May 2016 (UTC)

Dune-style sandworms couldn't exist for reasons other than size. You can't "swim" through sand like water. There's way too much friction between sand grains. --71.110.8.102 (talk) 02:33, 2 May 2016 (UTC)

Awww, but they are so awesome :( So you mean that what earthworms do in soil doesn't scale? Sagittarian Milky Way (talk) 03:06, 2 May 2016 (UTC)

Maybe it's an alien type of sand. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:18, 2 May 2016 (UTC)

The friction between sand grains can be greatly reduced by sonic lubrication. However, sand isn't very compressible, so they couldn't really tunnel through it like an earthworm does. Perhaps they could "swim" through it on the surface, though, somewhat like a sidewinder does. StuRat (talk) 04:04, 2 May 2016 (UTC)

Hey User:71.110.8.102: got a ref for that? Because I think you're wrong. I think think that if we allow smaller sized critters, they can swim through sand. I think that because here is some video of snakes and lizards swimming through sand [7]! It is produced by real research biologists and NYT. They used X-ray photography to see what is going on under the surface. Very cool stuff. Anyway, this we should post references at the reference desk, it is not a "post something I think is true" desk. You made a claim with no support, and OP believed you, and it turned out you gave false info. For that, I think you deserve a mild trouting. I also thought User:Sagittarian Milky Way, User:Baseball Bugs and User:StuRat might appreciate the update :) (P.S. I had read about this research when it came out, but I had to find it again. That NYT link was literally my top google hit for /move through sand/)SemanticMantis (talk) 15:18, 2 May 2016 (UTC)

To be fair, the OP was talking about Dune style sandworms, i.e. unprecedentedly large creatures that were supposed to be filter feeders deep underground. (How they filter feed from sand is an even bigger objection, I suppose) The NYT video is cool, but it shows animals that would come out and hunt, and it doesn't show them going very deep. They were still able to freely displace the sand upward along their path. I don't know what the scaling law is for pushing something up one body diameter though - if you suppose Dune sandworms were only as deep, relatively speaking, as the animals in the video, could they do it with an equal expenditure of energy relative to their size, or would the requirement scale up proportional to their diameter? Wnt (talk) 23:00, 2 May 2016 (UTC)

Since the largest plants are considerably larger than the largest animals, I would postulate that larger animals may be possible, but that they would then need to emulate plants. That is, they would need to move very little. We already have small animals that emulate plants, like corals and sea anemones. Is there some reason something like a single sea anemone, but with multiple mouths and digestion centers, couldn't grow and spread to cover many square kilometers of sea floor ? (The fact that it hasn't happened yet makes me think there are disadvantages versus many small ones.) StuRat (talk) 04:08, 2 May 2016 (UTC)

May 2

Dremels

inappropriate question. See Wikipedia:Medical disclaimer and Breaching experiment. WP:GAME is a good read as well. --Jayron32 00:19, 2 May 2016 (UTC)
The following discussion has been closed. Please do not modify it.
Could they, have they, been used for home dentistry? This is not a medical Q, it is a dentistry Q.--178.103.251.111 (talk) 22:39, 1 May 2016 (UTC) You could try googling your many questions first. I sense a pattern to them that is making me suspicious. --Aspro (talk) 23:12, 1 May 2016 (UTC) The reference desk policy is about not giving any medical advice or diagnosis, that does not "exclude" questions about dentistry. The benefit of answering your question has to outweigh the possibility that this is something you are considering doing yourself, and obviously you just writing that you aren't, isn't good enough evidence to convince us that there is any good real reason that anyone here should seriously answer your question. The primary purpose of the science reference desk is to help find and point people to relevant references related to scientific subjects, your question does not qualify, even loosely. Vespine (talk) 00:01, 2 May 2016 (UTC) Maybe he's looking to do a remake of Marathon Man. ←Baseball Bugs What's up, Doc? carrots→ 00:06, 2 May 2016 (UTC) Medical questions are OK, as long as you're not looking for advice, and this promises the most entertaining search results. YouTube boasts multiple videos like [8]. I haven't searched the Darwin Awards yet... a fun question to drill down into. Wnt (talk) 00:21, 2 May 2016 (UTC) Just a bit. ←Baseball Bugs What's up, Doc? carrots→ 00:30, 2 May 2016 (UTC)

Hey Bugs, you made me titter with that witticism (not a lot -- just a bit).--178.103.251.111 (talk) 23:08, 2 May 2016 (UTC)

It wasn't a real joke. It was just a drill. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:18, 3 May 2016 (UTC)

Wikipedia has an article about Dremel which is a brand of rotary tools suitable for use in the workshop. Another article describes the modern professional Dental drill which is characterized by high precision and needs to be disinfected between usages. Dentistry is the branch of medicine where licensed professionals treat the teeth. The Ref. desk will not speculate about unprofessional "home" tooth treatment or with misuse of equipment that may have occurred. AllBestFaith (talk) 09:30, 2 May 2016 (UTC)

• When I was doing brain surgery on rats, we used dremel tools to drill holes in the skull. They could be used for dentistry in a pinch, but are much more unwieldy than a proper dental drill. Looie496 (talk) 00:13, 3 May 2016 (UTC)

hmmmm

Why does Vanilla has some unnecessary Hydrogen bonds in a circle?

hydrogen bonds in a circle

Why can't H0 and OCH3 connect to the rest without this circle? --Ip80.123 (talk) 08:32, 2 May 2016 (UTC)

Those are carbon bonds. They are completely necessary to keep the molecule existing. Sagittarian Milky Way (talk) 08:51, 2 May 2016 (UTC)

See Aromaticity. The equivalent aliphatic aldehyde without the ring is 4-hydroxy-4-methoxybutanal, which (as far as I can tell) doesn't have any commercial uses. Tevildo (talk) 09:01, 2 May 2016 (UTC)

That chemical has a bunch of literature hits. "Commercial" is an unusually strict limit on why someone might care about a chemical:) The original poster really needs to clarify what is being envisioned as the structure "without this circle". I can think of lots of possible meanings, which have various levels of interest vs nonsense ideas to discuss. DMacks (talk) 14:11, 3 May 2016 (UTC)

See hydrogen bond for what a hydrogen bond is. For the "unnecessary bonds in a circle", see double bond to get started, then aromatic ring and resonance (chemistry) for advanced concepts. Wnt (talk) 10:26, 2 May 2016 (UTC)

If it was, it would be a cyclopropene, rather than a benzene (cyclohex-1,3,5-ene) based compound. LongHairedFop (talk) 17:55, 2 May 2016 (UTC)

Also, that hexagon in the middle is the Kekulé format for drawing a benzene ring. Not sure if the OP recognized that. The OP may also want to brush up on Skeletal formulas. --Jayron32 18:03, 2 May 2016 (UTC)

Exothermic reaction

why do I get an exothermic reaction if I fill sugar into a "Zero Drink" bottle? For example Sugar into the Coa-Cola-Zero. in just a few seconds shoots out the Cola out of the bottle when I fill sugar into it. Does so reacts the carcinogenic aspartame with sugar? Or why is the drink so unstable --Ip80.123 (talk) 08:40, 2 May 2016 (UTC)

This is discussed in some detail at Diet Coke and Mentos eruption. --Jayron32 11:14, 2 May 2016 (UTC)

Aspartame isn't carcinogenic. shoy (reactions) 13:21, 2 May 2016 (UTC)

How do you know this reaction is exothermic? If I mix baking soda and nitric acid, I get bubbles, but not an exothermic reaction. --OuroborosCobra (talk) 14:23, 2 May 2016 (UTC)

Actually, I'm 99% certain the reaction is endothermic. Since there is not a proper chemical reaction here, just a phase transition: carbon dioxide going from the aqueous phase to the gas phase. That phase transition should always be endothermic. --Jayron32 14:27, 2 May 2016 (UTC)

• whispers* was trying to get the questioner there; I suppose its the chemistry TA in me. --OuroborosCobra (talk) 14:29, 2 May 2016 (UTC)

• whispers back* I can't let a chemistry question go unanswered. I suppose its the chemistry teacher in me. --Jayron32 14:30, 2 May 2016 (UTC)

As a non-chemist with a loud voice ;-) can we not just put a thermometer in it? DrChrissy ^(talk) 14:36, 2 May 2016 (UTC)

You could just hold it. You'll feel it get colder. --Jayron32 14:50, 2 May 2016 (UTC)

No dear Jayron32, Mentos very often has 0% sugar in it. And mentos does a reaction also with regular normal cola, when I fill sugar into normal cola there happens nothing. Yes it is carcinogenic, shoy. It is. --Ip80.123 (talk) 09:21, 3 May 2016 (UTC)

If you can't be bothered to read the articles we have linked for you, then we cannot help you. --Jayron32 11:41, 3 May 2016 (UTC)

Ip, the reason why Mentos does this even containing no sugar is that this isn't a chemical reaction, it is a physical reaction. That you have observed this is a great hint, but rather than applying the scientific method, you seem to have rejected your results based on preconceived notions. As a physical reaction, it doesn't matter what chemical species is present as long as other physical properties are met, such as a rough, high surface area material. I've done the same thing using salt. You need nucleation sites, not a specific chemical species. No bonds are being made or broken. --OuroborosCobra (talk) 12:01, 3 May 2016 (UTC)

Safety of aspartame would disagree with you, unless you're trolling with your definition of the word. shoy (reactions) 14:11, 3 May 2016 (UTC)

Energy of elementary particles and forces

Why do elementary particles in theír ground state never lose their properties and keep moving forever? What is their continuous energy supply? '202.58.203.82 (talk)' —Preceding undated comment added 09:23, 2 May 2016 (UTC)

They don't need a continuous supply of energy, they just need not to lose energy during their interactions with other particles in order to keep moving forever. Dbfirs 09:33, 2 May 2016 (UTC)

Newton's First Law of Motion says a particle either remains at rest or continues to move at a constant velocity, unless acted upon by a force. Thus no external supply of energy is needed for the particle to continue moving indefinitely. AllBestFaith (talk) 09:35, 2 May 2016 (UTC)

Elementary particles obey more complex laws, such as Quantum mechanics, while in general the principle of Newton's first law holds, there are some complexities, such as the problems of charged particles accelerating (see Larmor formula#Atomic physics) that have to be accounted for by quantization of energy as explained by QM. --Jayron32 12:47, 2 May 2016 (UTC)

Yes, I originally started typing a link to Newton's First Law above, then deleted it because of the complexities. The energy argument holds, doesn't it? Dbfirs 13:03, 2 May 2016 (UTC)

They do, and Newton's first law holds, broadly speaking, however thinking about elementary particles as little rigid spheres flying through space creates MAJOR issues that can only be resolved by quantum mechanics. I just don't want people getting the idea that an electron is a tiny little sphere orbiting a bunch of tiny little spheres we call protons and neutrons. That sort of model doesn't hold up. --Jayron32 13:40, 2 May 2016 (UTC)

I hold up that model of "solid spheres orbiting solid spheres" all the time. As an example of a model that is nonsense. DMacks (talk) 14:03, 3 May 2016 (UTC)

I was not asking about solid spheres, but about energy. What is the true nature of energy, and why is it constant?202.58.203.82 (talk) 03:52, 4 May 2016 (UTC)

The general answer you'll see in a university level textbook is that it's because the universe is time invariant. In other words, for most purposes, the laws of physics today are the same as they were yesterday and as they will be tomorrow.* Noether's theorem states that this kind of invariance means something is being conserved, and in this case, that conservation law is conservation of energy. So from that perspective the reason that energy is conserved is that the laws of physics are constant with time (you might ask why they are constant, but intuitively it makes sense). Smurrayinchester 09:57, 4 May 2016 (UTC)

* I'm sure there was a discussion here about one specific case where the laws of physics are not invariant - the expansion of the universe - and how this means that in some specific circumstances energy is not conserved: a photon from the early universe will get redshifted by the expansion of space, which causes its energy to decrease, but the energy doesn't go anywhere. I can't find it in the archives though. Smurrayinchester 09:57, 4 May 2016 (UTC)

What if the enery of the photon goes into expanding the universe? In tandem with neutrinos maybe?202.58.203.82 (talk) 06:34, 5 May 2016 (UTC)

Civil engineers in the private sector

Do all civil engineers in the private sector have to think about profit for their company? 2A02:C7D:B957:F500:6596:55DA:4867:C538 (talk) 09:52, 2 May 2016 (UTC)

A business Company has a legitimate aim of gaining a profit unless it is constituted as a Nonprofit organization. Civil engineers who are employees are hired to contribute labor and specialised expertese to the company and they are assessed according to whether they achieve a profitable, productive and ethical performance. AllBestFaith (talk) 11:12, 2 May 2016 (UTC)

Not necessarily. Generally an employee has to think about whatever their immediate supervisor tells them to think about. A low level engineer in a large firm may spend little or no time thinking about profit, instead focusing on other details within various constraints provided for them. A supervising engineer in a management role will likely have to devote a lot of thought to costs and economics. A lot depends on the engineer's role and responsibilities within the company. Dragons flight (talk) 11:23, 2 May 2016 (UTC)

Yes. Economics is a regular part of engineers education and generally one of the main concerns in design, tho companies like to keep that a secret. --Kharon (talk) 08:46, 3 May 2016 (UTC)

How to determine the average length of a generation in humans?

Is it okay to put a range from 15-45 years, with the mean, median, and mode? How do extreme ages factor in? 140.254.70.33 (talk) 12:14, 2 May 2016 (UTC)

It depends on who and when and where. But extreme age doesn't really figure into it - it's spawning the next generation. So if you produced kids when your were 25 to 35 years old, that's your own next generation. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:38, 2 May 2016 (UTC)

This looks relevant. --Jayron32 12:44, 2 May 2016 (UTC)

Historically, it's 20 years (.i.e. "baby boom" 1945-1964, inclusive). Pop culture has tried to shorten it science has lengthened it. It's not clear that the relationship is simply when parents have children but also sociologically relational (i.e. how much does a 35 y/o have in common with a 15 y/o?). --DHeyward (talk) 15:39, 2 May 2016 (UTC)

There is plenty of data on the average age of women at the birth of their first child - which varies enormously in different parts of the world (from 18 in parts of Africa to over 30 in parts of Europe, and Japan). Try this list - https://www.cia.gov/library/publications/the-world-factbook/fields/2256.html 81.132.106.10 (talk) 21:30, 2 May 2016 (UTC)

What is the incentive behind taking vitamins as opposed to eating fruits and vegetables?

Some people don't want to eat fruits and vegetables? Vegetables taste bitter to some people? Fruits are too watery and messy for some people? Allergic reactions to some fruits and vegetables? 140.254.70.33 (talk) 12:45, 2 May 2016 (UTC)

Wikipedia has an article titled Food choice that would provide a place for you to start your research. --Jayron32 12:49, 2 May 2016 (UTC)

There is such a range of fruit and vegetables that there really can be no justification for not eating any of them. There are vegetables which do not taste bitter, and fruit which is not watery or messy. Even allergies rarely mean that you react to all of them. 81.132.106.10 (talk) 14:11, 2 May 2016 (UTC)

It's easier just to pop a pill. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:59, 2 May 2016 (UTC)

Where would you pop it? I have a suggestion for you...--178.103.251.111 (talk) 23:15, 2 May 2016 (UTC)

I'll get back to you after your next block expires. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:15, 3 May 2016 (UTC)

Depends whether you get blocked before I do, doesnt it?--178.103.251.111 (talk) 22:51, 3 May 2016 (UTC)

Some reasons why people take vitamins (and minerals and other micronutrients):

1) The mistaken belief that more is better. This isn't true of most micronutrients, and some, like vitamin A are even harmful if you overdose.

2) To compensate for an unhealthy diet. Of course, this is of limited value, since not all micronutrients are provided in a form that can be readily absorbed in pill form. Also, the pills won't get rid of the harmful things you eat.

3) Vitamin D is a special case, since it's produced naturally in our skin from UV light. Since we are now trying to avoid UV light because it causes skin cancer and wrinkles, many people are deficient in Vitamin D.

4) Vegetarians are another special case, since they may lack certain nutrients, like iron and vitamin B-12.

5) Various health problems and/or meds may be cause to take other micronutirents. StuRat (talk) 00:17, 3 May 2016 (UTC)

The main incentive is the the amount of bull**** advertisements that tell people they need extra vitamins to maintain their health or avoid this or that disease or condition coupled with the ignorance of the reader who doesn't understand the fallacy of the suggestion. We are talking market forces as a driver, the acquisition of your money by unscrupulous companies. Richard Avery (talk) 06:56, 3 May 2016 (UTC)

Yes, advertising seeks to introduce then reinforce all the misconceptions about the health benefits of taking pills. StuRat (talk) 16:01, 3 May 2016 (UTC)

(Sorry, just a comment:) It's not really an either-or thing, and it at least seems like a cheap and harmless thing to do. If you feel out of sorts, or somebody sniffled next to you in the office, or you binge on the bad stuff rather than the good, you take a pill. There are a lot of Plan Bs in life. Wnt (talk) 10:45, 3 May 2016 (UTC)

They can cause harm, especially nutritional supplements from China, etc., which may have harmful ingredients not meant for human consumption. StuRat (talk) 16:01, 3 May 2016 (UTC)

Quite a lot of vegetables taste disgusting, or require what is perceived as an excessive amount of time and effort to turn into something palatable. People then eat less of the things than they are told they should, feel guilty, and take vitamins as a "well it's better than nothing" way of dealing with it. DuncanHill (talk) 16:10, 3 May 2016 (UTC)

But "taste disgusting" is a relative thing. If your normal diet is entirely junk food, then anything else may taste bad. But, if you eat veggies regularly, they won't taste bad. And if you were starving, they would taste delicious. StuRat (talk) 19:31, 3 May 2016 (UTC)

It's perfectly possible not to eat much veg without eating "entirely" or even any junk food. Some vegetables - potatoes, swedes, onions, runner beans for example, are delicious, especially with a bit of butter. DuncanHill (talk) 20:30, 3 May 2016 (UTC)

You eat Swedes ? I try to avoid cannibalizing Swedes. I find Italians much tastier, as they have been pre-marinated in wine and garlic. StuRat (talk) 20:33, 3 May 2016 (UTC)

Just their meatballs. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:42, 3 May 2016 (UTC)

No one has mentioned that vitamin pills are Dietary supplements and as such are NOT regulated by the FDA, in the States anyway. By definition they are not intended to treat or prevent any disease, but the supplement industry is constantly pushing the boundaries of what kinds of claims they can get away with. Notice how many supplements and 'alternative medicines' claim they "boost the immune system", this is because this is a clinically meaningless claim and they can get away with it. Vespine (talk) 22:50, 3 May 2016 (UTC)

Does quantum physics really matter?

When we analyze phenomenon like consciousness? That's what comes to mind to me, since people talking about conscious often relate it to quantic phenomena. Anyway, do we understand something better about consciousness since quantum physics was discovered? --Llaanngg (talk) 16:47, 2 May 2016 (UTC)

There is no known direct connection between quantum physics and consciousness. See Wikipedia's article titled Consciousness which discusses it in some details. Quantum physics has nothing in particular to do with it, excepting where quantum physics has to do with everything (such as how atoms and molecules work, etc.) --Jayron32 16:50, 2 May 2016 (UTC)

For starters, we don't understand quantum physics. YohanN7 (talk) 16:53, 2 May 2016 (UTC)

Quantum_mind describes how some people think that consciousness might somehow depend on quantum weirdness or other strange bits of quantum mechanics. The jury is still out of course, and our article reports no conclusive findings, just interesting hypotheses. The Hard problem of consciousness, unsurprisingly, remains hard. SemanticMantis (talk) 16:55, 2 May 2016 (UTC)

Of course the word quantum is used A LOT in the context of consciousness by people who have very little idea what they're talking about to sound pseudo profound. Vespine (talk) 00:08, 3 May 2016 (UTC)

"Quantum" is used a lot by people who want to sound sciency or profound but have no idea what they are talking about. We have an article on Quantum mysticism if you want to read more about it. (I found the article trough the redirect "quantum quackery" which I think is a more apt description.) Sjö (talk) 07:39, 3 May 2016 (UTC)

In the mean time found: What the Bleep Do We Know!? and a review of itLlaanngg (talk) 17:48, 3 May 2016 (UTC)

People insist in not wanting to believe that our minds (and especially our conscious minds) are ruled by simpler "classical" laws of physics - so they clutch at the phenomena that are least well understood (at least by them!) - and that's quantum theory. Sadly, this fails utterly to reveal any actual insights to the problem that aren't equally well covered by the chaotic behavior (in the mathematical sense of "chaos theory") of a system as ungodly complex as the brain.

Quantum theory is very important - but not at the level of such macroscopic things as neurons, synapses and such. SteveBaker (talk) 17:52, 3 May 2016 (UTC)

Well, technically speaking, all objects obey the laws of quantum physics: it doesn't stop working at some magical bright line. It's just that the laws of quantum physics reduce to the laws of classical physics (that is, they produce the same answers, to any meaningful measure) for any object larger than a molecule. That's why we don't use complex quantum physics equations to model the behavior of macroscopic phenomena: while the Quantum models produce the right answer, the simpler classical models produce the same right answer. --Jayron32 19:13, 3 May 2016 (UTC)

were the birds mating?

was walking down a sidewalk on a city street...just off the sidewalk on cement ground near a building two birds lying sprawled out in close proximity (actually touching I think) seemingly dead..my initial thought was that they had flown into the side of the building and were dead as a result..I then noticed one flutter so looked closer...nudged one with my foot...then they both jumped up and flew away like bats out of hell, seemingly completely healthy...it was very odd..I've never seen birds on the ground like this unless they were dead...the birds were black and about the size of a cardinal..this was in Michigan, USA....were the birds just mating? couldn't find much about mating positions for songbirds etc or anything quite like what I saw...68.48.241.158 (talk) 21:03, 2 May 2016 (UTC)

Most birds mate very quickly, only a second or so. Another suggestion is that they were playing dead to lure you away from their nest. I suspect they had a nest with eggs in it (or maybe chicks) nearby that you didn't spot. Also, if you are in the Northern Hemisphere, where it is now spring, it's a little late to just be mating now. It's time for hatching now. StuRat (talk) 00:05, 3 May 2016 (UTC)

Any references on the mating habits of birds so the OP can learn more about the subject? Or just half remembered factoids and suggestions? --Jayron32 01:13, 3 May 2016 (UTC)

yeah, from what I read I don't think it was mating activity either...it was strange...they were like zonked out dead and like practically right on top of each other...never seen anything like it....it's possible they were flying after each other and both ran into the building and were lying there stunned for a bit...I've seen birds chase each other around etc...I didn't sneak up on them but noticed them lying there and walked over so not like I scared them into playing dead..I didn't even know birds did such a thing...anyway..might just be one of those odd occurrences..68.48.241.158 (talk) 00:42, 3 May 2016 (UTC)

Help us out OP, we need more info to make even an educated guess. How were they touching? At the feet/beak/wing/tail/other? Did you see them land, if so how/where? What time of day was it? Did they make any noise? Was this a dense urban area or a suburb, or other? Were they perhaps grackles or starlings? (Probably not a red-winged blackbird?)

I have some suspicions but I'll save them until I get more detail :) In the meantime, you can check out our article on male-male competition, this book chapter, [9], or this [10] scholarly review article on the topic. SemanticMantis (talk) 02:59, 3 May 2016 (UTC)

yes, something along the lines of grackles or starlings...was about 5pm, southeastern Michigan...in the downtown area of a suburban town center...lots of farmland/woods within a mile or two...they looked identical so likely the same sex...I'm certain the position they were in had nothing to do with me or my presence...I was the only pedestrian in the immediate area..they were lying side by side and I'm quite sure even touching....totally still for the first couple of seconds I noticed them from a distance...one then fluttered a little so I walked over and then nudged one with my shoe...they continued to appear dead or injured but then suddenly both flew off at a high rate of speed in the same direction and basically side by side...it was a strange nature encounter..68.48.241.158 (talk) 03:58, 3 May 2016 (UTC)

Sure sounds like playing dead to me, although perhaps just lying still so you wouldn't spot them. This strategy might be more effective against predators with worse vision than us. Cats, for example, are good at spotting motion but seem to have trouble seeing much detail on still objects. Note that the "completely still then escaping at full speed" pattern is one you see a lot in prey animals. Once they realize they've been spotted, then it's time to change strategies and run for it (or fly for it, in this case). StuRat (talk) 05:17, 3 May 2016 (UTC)

I can find no reference to urban birds using distraction strategies to protect their nests which are usually built in available vegetation or in/on buildings or other available structures. The feigning dead strategy is more usually used by birds who build nests or incubate their eggs on the ground. Could they have been sunning themselves and had their eyes closed in the rapture of it. Richard Avery (talk) 06:49, 3 May 2016 (UTC)

If they were nearly on top of one another, only one of them would have been effectively sunning itself. Rather awkward for the one underneath... Evan ^{(talk|contribs)} 07:47, 3 May 2016 (UTC)

And they may not be "urban birds", meaning those that regularly live in cities, like pigeons. They are close to nature, and we often get wild animals encroaching slightly into developed areas (or vice versa). StuRat (talk) 15:53, 3 May 2016 (UTC)

Clues: springtime, 5pm, lying on concrete. My guess: they were lying there soaking up the warmth that had been retained by the concrete from the sun's rays earlier in the afternoon. Akld guy (talk) 08:57, 3 May 2016 (UTC)

Thanks for the extra info. Here [11] is a pay-walled article on male-male competition in the boat-tailed grackle, let me know if you'd like a copy. I think WP:OR the birds you saw were fighting. I say this because I've seen great-tailed grackles exhibit very similar behavior. In my case, I was sitting at an outdoor table in a light urban/suburban core context, and saw the fight start. After much squawking and flapping, they ended up with their feet clasped together. After some leg wrestling, they stopped, laying in the street, seemingly dead. But after they were suitably rested/disturbed, they both got up and left. Usually, these sparring matches among juveniles are fairly abstracted, but sometimes they can go pretty far. Things like grackles, sparrows, starlings, and other human commensal species often reach much higher densities in cities than they could in the wild, and this may increase the incidence and intensity of fighting for mates. This is of course not a positive ID of the behavior, but it does sound very similar to a strange bird fight I saw :)SemanticMantis (talk) 13:44, 3 May 2016 (UTC)

I think you're exactly right the more I've thought about it...they may have been sort of touching at the feet, as if they had been clawing at each other...but does seem they were perhaps in a daze from fighting/exhausted...and when I finally nudged at them it was enough to give them another burst of adrenaline to finally fly away from me...it was interesting..68.48.241.158 (talk) 14:02, 3 May 2016 (UTC)

May 3

Energy of elementary particles and forces

Why is it that elementary particles and forces in their ground state keep going forever with whatever they are doing? What feeds the required energy to them?202.58.203.82 (talk) 02:10, 3 May 2016 (UTC)

You asked this question yesterday and it had responses. See: Wikipedia:Reference desk/Science#Energy of elementary particles and forces JoshMuirWikipedia (talk) 06:06, 3 May 2016 (UTC)

There's nothing to stop them. Dbfirs 13:25, 3 May 2016 (UTC)

Water-damaged tablet displays vertical bands of white

Days in a bin of rice haven't reversed the most visible damage. What is likely the cause of the vertical bands? Thank you. Imagine Reason (talk) 14:40, 3 May 2016 (UTC)

Have you tried asking at the Computing Reference Desk? --Jayron32 15:35, 3 May 2016 (UTC)

Sorry, I forgot. Imagine Reason (talk) 16:25, 3 May 2016 (UTC)

One guess: there's either still some water, or else residue of whatever was dissolved in the water, where the display cable plugs in (if you give us the model of the tablet we should be able to figure out if this is a possibility). If you can take it apart, you might try unplugging it and cleaning the contacts with a cotton swab and alcohol. Of course, doing anything like this carries a risk of destroying it, so you might want a professional to do it. StuRat (talk) 15:46, 3 May 2016 (UTC)

It's the Lenovo S8-50. Imagine Reason (talk) 16:25, 3 May 2016 (UTC)

[12] seems to say it lacks an output to an external monitor. Too bad, because that would help you to figure out where the problem lies (if the external monitor still had those lines, then the problem is in the graphics processor, if not, it's in the connection to the display). Also, if the external monitor looked good, you could use it that way most of the time, and just live with the lines when you needed to use it where no external monitor was available. StuRat (talk) 16:47, 3 May 2016 (UTC)

Professional don't like to do it because tablets can be notoriously tricky to dissemble and resemble and most repair men are software orientated any way. If the whole screen is banded then that’s probable the graphics processor on the motherboard that needs cleaning. Don't use mentholated spirits but Isopropanol . Just the odd line on the screen though, is probable an address line on the screen shorting out (try it by pressing the screen gently in that edge spot). Same thing, clean edge of screen terminals with care. You have little to loose because the device has had it otherwise. Last thoughts, is it still under warranty? If it wasn’t submerged long enough to start sprouting barnacles, then you might be able to get it replaced free of charge. Get you data off first before parting company with it.--Aspro (talk) 16:10, 3 May 2016 (UTC)

The are multiple such lines of varying widths. They don't cover up the display and it's more apparent on the home screen than in at least one app, although the lines reappear at undetermined intervals. It's out of warranty I think and I doubt it got so small a soaking that they wouldn't notice it. As I said, it's obviously on the display. Imagine Reason (talk) 16:25, 3 May 2016 (UTC)

Vertical stripes are caused by some of the addressing circuitry or wiring leading from the graphics chip to the display...or within the display itself. If one or two low-order bits of the address lines are broken or shorted, you get this effect. Sadly, that probably won't help you in getting it fixed. SteveBaker (talk) 17:46, 3 May 2016 (UTC)

• Now that you have identified the device, I can link to a video to show why a professional (unless he is being paid oodles of taxpayers money by the NSA or CIA) would not touch it, as it would cost you more than the current value of said tablet. Disassembly Lenovo S850 Observe what has to be done to remove case without damaging the circuitry. However, if you wish to persevere then notice that at about 6 minutes into the video he reattaches the screen via a little ribbon cable. This is more than likely were the problem lays regarding your reported symptoms. With the ribbon cable separated, an aerosol can of 'Contact Cleaner' might just do the trick. --Aspro (talk) 18:00, 3 May 2016 (UTC)

Agreed. It might be better to get a new one and just use this old one as a backup in case the primary goes down. StuRat (talk) 19:36, 3 May 2016 (UTC)

Please note that the S8-50 is not the same as the S850. Mine, the former, is an 8-inch tablet. Here's a teardown?[13] Imagine Reason (talk) 23:09, 3 May 2016 (UTC)

Can't comment much on the S850 since it's a video and it's annoying to watch just to get an idea of what's involved but the S8-50 doesn't look that hard. I replaced the screen on my S4 Mini (not something I purchased but won) without AFAIK breaking anything and I'd never done anything similar before other than help a friend take off the back cover of their Nexus 4 to replace the batter. I think the S4 Mini was slightly easier than the S850 looks since it used more Philips screws and not much stick tape that needed to be heated (but the Nexus 4 did use similar); except that I bought the screen without the bezel partially due to confusion and removing the old screen did partially require this. (Although mostly the old screen got completely destroyed, however it was not working at all so it was no big loss.)

But the S8-50 doesn't even seem to have that although you may have to be slightly carefully when using the guitar pick since if it's not using sticky tape or screws, I guess there are some clips which could be damage. Still it looks far easier than an iPhone for example.

That said, as SteveBaker has said, it's difficult to be sure what's wrong. There's a slight chance fooling around with the ribbon cable may help, but it may also be the screen or something else is damaged. Not really sure how cleaning the SOC (who uses a seperate GPU on a tablet?) is supposed to help whatever was showing, it's very unlikely to. Given the uncertainty over whether replacing the screen will help, I'm not sure if it'll be worth it in your case unless you can find someone who'll let you return the screen even if it's not defective (if you only attach the ribbon cable there's a slight chance someone will be like that). But you could try taking it apart and cleaning everything as it sounds like it'll be of very limited utility anyway.

Nil Einne (talk) 07:48, 4 May 2016 (UTC)

possible earth-like planets orbiting single stars

Are there any known possible earth-like planets that orbit single stars? — Preceding unsigned comment added by 24.207.71.235 (talk) 18:15, 3 May 2016 (UTC)

What are known possible earth-like planets? Robert McClenon (talk) 18:21, 3 May 2016 (UTC)

Are our methods of detecting extrasolar planets sufficiently precise that we can detect earth-sized planets? If so, are they sufficiently precise that we can detect earth-sized planets if the system also includes a Jupiter-sized planet? Robert McClenon (talk) 18:21, 3 May 2016 (UTC)

Earth analog. Henry^Flower 18:24, 3 May 2016 (UTC)

Earth-sized planets orbiting single stars.24.207.71.235 (talk) 20:00, 3 May 2016 (UTC)

Coincidentally I was just reading about this recent discovery of exoplanets believed to be between half and double the Earth's mass. AndrewWTaylor (talk) 20:20, 3 May 2016 (UTC)

Since you seem to not have read the article Henry helpfully linked above, I did it for you and pulled out the link to our list of potentially habitable exoplanets. --71.110.8.102 (talk) 21:07, 3 May 2016 (UTC)

Thank you. That list provides enough information that if a reader thinks that particular planetary circumstances are not suitable for Earth-like life, that reader can eliminate those planets. For instance, some theorists think that planets in the habitable zones of M-type stars are not good life candidates, because of the high likelihood of tidal lock. Of course, different theories as to habitability differ. As the article on Drake equation points out, the Drake equation has zero degrees of freedom with only a single known habitable planet. In any case, we are here. Robert McClenon (talk) 16:56, 4 May 2016 (UTC)

why does wind feel colder than still air

If movement creates heat, then shouldnt moving air feel warmer than still air? — Preceding unsigned comment added by 24.207.71.235 (talk) 18:18, 3 May 2016 (UTC)

See wind chill. --Jayron32 18:24, 3 May 2016 (UTC)

(ec)Read Wind chill and it should become clear. The cold wind is pulling heat from you faster than still, cold air would. And I can tell you from experience in the American Midwest that minus-20 with calm air is a lot more tolerable than minus-20 with significant wind. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:26, 3 May 2016 (UTC)

From memory, each knot of wind only increases the topographic temperature by 0.007 degrees centigrade (think that the right order of magnitude). Therefore, air currents blows away the envelope of warmed air around the body (clothes mitigate this as they 'trap' this body-warmed air). Eject from a plane at Mach 2 however, then obviously one will suffer a momentary heat-pulse until one slows down a bit.--Aspro (talk) 18:32, 3 May 2016 (UTC)

I know of 2 reasons:

1) Wind blows away the warm air envelope around your body, as Aspro mentioned above. This obviously only applies when the air the replaces the air blown away is cooler.

2) That same air envelope is also moist. Blowing that away and replacing it with drier air then causes moisture on your skin to evaporate more quickly, causing increased evaporative cooling. This obviously only applies when the air that replaces the air blown away is drier.

So, if the outside air is hotter and moister than the air envelope around you, then wind won't help to cool you down. In fact, it will heat you up more quickly, just like a convection oven cooks food more quickly than a normal oven (but if it's that hot and humid out you will overheat in any case, it's just a matter of when). StuRat (talk) 19:09, 3 May 2016 (UTC)

The simplest explanation is that air currents (convection) of any sort speeds heat transfer, always. That is, moving air speeds the rate at which heat either moves into or out of an object. The laws of thermodynamics don't particularly care which direction the heat is moving. If the air is cooler than the object, wind will cool off the object faster than still air. If the air is warmer than the object (as in a convection oven) it will heat the object faster. It's that simple. --Jayron32 19:31, 3 May 2016 (UTC)

I've experienced 115+ degrees Fahrenheit in Las Vegas in July...I truly remember the breeze making things worse...the other odd thing is that you're sweating like mad but have no idea that you are as the evaporation is instantaneous...68.48.241.158 (talk) 19:33, 3 May 2016 (UTC)

It's a good thing you were sweating so much, as your body temp would otherwise quickly match or surpass the environmental temp, and you would die. (I believe people in such a situation do quickly die once they run out of water.) StuRat (talk) 19:40, 3 May 2016 (UTC)

Anhidrosis indeed. DMacks (talk) 21:38, 3 May 2016 (UTC)

Unidentified lichen (?)

Is this a lichen? Which? This was photographed in northern Georgia (country) . Etan J. Tal^(talk) 21:33, 3 May 2016 (UTC)

Yes, it's lichen. Try Physcia and see where that takes you. Richard Avery (talk) 21:54, 3 May 2016 (UTC)

Yep, lichen ID can be very hard though! Our only non-redlink article in the Physcia genus is Physcia_stellaris, which does look a lot like OP's photo, as well as the lichen I see all over my pecans in TX. Here [14] is a nice lichen ID resource from the USFS, including several good external links. SemanticMantis (talk) 22:02, 3 May 2016 (UTC)

I'm lichen this answer. StuRat (talk) 02:33, 4 May 2016 (UTC)

Name a technical device.

The lenses of modern photo and video cameras change focal distance. What is the name for this principle, or this type of lens?

I also have another question. Do lenses exist that change the focal distance electronically via voltage application?

Thanks, --AboutFace 22 (talk) 22:56, 3 May 2016 (UTC)

for your first question, see Zoom lens. For your second question - you need to be more specific. Do you mean electrically driven zoom mechanism, do you mean "Digital zoom" where the lens does not actually move but the image is magnified and cropped electronically, or do you mean an actual optical element changing its curvature or refraction coefficient when voltage is applied across it? --Dr Dima (talk) 23:03, 3 May 2016 (UTC)

Actually, a zoom lens is one for which the focal length can be held constant while changing only the magnification. The original question asked for a lens whose focal length can change - technically, no single lens made of rigid glass or plastic is able to do that - but a lens group can. In common parlance, photographers often say a "lens" when they actually mean several lenses - rather, "a large, engineered optical device containing several pieces of glass and a special mechanism to hold those glass pieces in a carefully-calibrated optical alignment." We have an article on photographic lens design; and I can't recommend this book highly enough, Applied Photographic Optics - though it is regrettably quite expensive!

We also have an excellent article, History of photographic lens design. It is possible that our OP is looking for a specific lens type - like the 3-element Abbe lens grouping; or the Cooke triplet, or one of the more famous complex lens groupings that, for example, allow a focal length change while maintaining a very precisely carefully controlled field-of-view.

Lenses that are non-rigid have been studied for a very long time - ever since people started building optics. The human eye lens works in that fashion; and many optical engineers have tried to mimic that machine - but there are no commercially-available flexible-lens technologies today, electronically-actuated or otherwise, that can compete with the performance of rigid-glass lens mechanisms. Nimur (talk) 02:06, 4 May 2016 (UTC)

I think you might be wrong about your first statement Numur, magnification IS the angle of view IS the "focal length", a zoom lens is called something like 55mm-105mm, meaning that you can vary it's focal length from 55mm all the way to 105mm, this changes the magnification and the angle of view and the focal length, it's all essentially the same thing. Vespine (talk) 02:14, 4 May 2016 (UTC)

As described below ... there are multiple focal lengths because modern systems have multiple elements. Permit me to admit my guilt - I am participating in abuse of terminology as much as anybody else. Nimur (talk) 06:32, 4 May 2016 (UTC)

If you mean the latter - an optical element which will change its properties when voltage (electric field) is applied to it - you may want to read electro-optic effect, Pockels effect, and Kerr effect. Kerr effect, in particular, is used in femtosecond laser optics; but I am unaware of any use of these effects to change focal lengths of photographic or video lenses. --Dr Dima (talk) 23:17, 3 May 2016 (UTC)

Focal length is the principle, I'm not sure if that's synonymous with "focal distance", or if you mean something slightly different. A lens with a fixed focal length can still have a focus ring to change the distance at which it will achieve focus, it can also have an aperture which will govern the depth of field. Vespine (talk) 02:11, 4 May 2016 (UTC)

The term is used and abused badly in various contexts. Modern optical systems have multiple different focal lengths. Nimur (talk) 02:14, 4 May 2016 (UTC)

allow a focal length change while maintaining a very precisely carefully controlled field-of-view. you need to explain this to me please. I've studied photography and am an amateur astronomer and I'm struggling to figure out how to change focal length while maintaining a uniform field of view. Vespine (talk) 02:19, 4 May 2016 (UTC)

from the Focal length article: Focal length (f) and field of view (FOV) of a lens are inversely proportional. For a standard rectilinear lens, FOV = 2 arctan x/2f, where x is the diagonal of the film. So unless the camera system dynamically changes the sensor size, i don't see how you can alter the FL without also altering the FOV. Vespine (talk) 02:23, 4 May 2016 (UTC)

The effective focal length of the entire optical system can differ from, e.g., the back flange focal length. Ultimately, this is purely an issue of nomenclature and conventions when describing lens systems that contain multiple lenses. I am in otherwise complete agreement with your statements: focal length and magnification and field of view are all intrinsically related - but the issue stems from the fact that each individual lens in a multi-element group may have a distinct focal length. Modern devices can change total effective focal length, while holding back-plane focal length constant, using complex gearing systems to adjust the relative position of each element. Nimur (talk) 06:27, 4 May 2016 (UTC)

Thank you very much. A lot to digest for me now. For some reason I thought "zoom" is a process but the lens could have a different name. A very fascinating topic. Thank you. --AboutFace 22 (talk) 16:18, 4 May 2016 (UTC)

@Dr. Dima, I actually meant changing the curvature of the lens with applied voltage. Although I consider myself technically adept with considerable math background, the optics is the farthest from my regular interests. Now I have an opportunity to hone some concepts and definitions. Again I am very grateful for all contributions. --AboutFace 22 (talk) 16:37, 4 May 2016 (UTC)

May 4

Newton trying to convince people that energy is physical

Hi all - is it true that Newton found it difficult to convince others that energy is physical, in the same way that people find it hard to think of information as physical? If so, can someone cite some references? Thanks Adambrowne666 (talk) 02:38, 4 May 2016 (UTC)

This is a bit philosophical. I'm not a student of Newton or anything, I did some university physics, but I'm not sure any physicist considers "energy" it self to be physical. In fact I find this is one of the biggest misconception held by most people; that energy IS a physical "thing", that you can have a jar full of "energy" or a ball of "energy" can fly through space, or that the human body has some "energy field", or that there is such a thing as "pure energy". Energy is a property of physical things or systems, it's not it self a physical "thing". Vespine (talk) 03:54, 4 May 2016 (UTC)

Unless of course you mean Mass–energy_equivalence then I take back all of the above, but Newton predates that by a few centuries. Vespine (talk) 03:55, 4 May 2016 (UTC)

Yeah, maybe I'm putting it wrong - what I mean is, I've heard that Newton had difficulty in getting people to think of energy as a thing - a property that can be discussed in the same way that weight is... Am I getting closer? Adambrowne666 (talk) 04:12, 4 May 2016 (UTC)

Riiight. Ok, i think I understand. I have not heard about it specifically related to Newton, are you perhaps thinking of Caloric theory? Vespine (talk) 05:20, 4 May 2016 (UTC)

Did Newton's even have a conception of energy? I'm not sure that he did. I thought that energy was largely developed as a concept in the 19th Century, in part because of heat–kinetic energy equivalence noted in the steam engine, and in part from Hamilton's reformulation of mechanics. — Preceding unsigned comment added by Star trooper man (talk • contribs) 10:18, 4 May 2016 (UTC)

"Earlier workers, including Newton and Voltaire, had all believed that "energy" (so far as they understood the concept at all) was not distinct from momentum and therefore proportional to velocity." From Conservation_of_energy#History. More good stuff in that section too. SemanticMantis (talk) 13:57, 4 May 2016 (UTC)

I would have thought that the problem was the reverse of that. Newton was an alchemist - and some of those guys (but evidently not Newton) believed in Phlogiston theory - where phlogiston is a physical substance (albeit with a negative mass!) that had properties somewhat similar to the modern concept of "energy". So I'd have expected Newton to have to work hard to demonstrate that energy was not a physical thing - but merely a measurement akin to "mass", "charge" or "temperature". SteveBaker (talk) 01:05, 5 May 2016 (UTC)

Take the idea that the sun warms the ocean and causes water to evaporate. Then some of that water falls upon high ground and forms a river which runs downhill and works a mill. which grinds corn. Today, we all understand that energy is being transferred from one form to another, but is conserved. If it is cold, less rain is formed, and less wheat is ground. This everyday notion of the conservation and transformation of energy is so common today that we forget that is was an alien concept before Newton. Philosophers assumed that different types of natural events had their own way of doing things, Celestial objects worked according to their own laws, very different those which were found on Earth. The vitalist forces which made life possible were set apart from those which determined the weather. The notion that energy permeates very different systems, and is conserved, that is, cannot be created or destroyed suddenly made a single calculus the measure of ALL things, and thus was, probably, the foundation of modern science. I presume that this is what is meant by the OP talking of energy being physical. Myles325a (talk) 05:21, 5 May 2016 (UTC)

Thanks for your answers, all - it's clearly a case of memory being a peeling wallpaper over the walls of the vast chamber of forgetting - still, it's good to have it cleared up Adambrowne666 (talk) 01:01, 6 May 2016 (UTC)

Why is a kidney dish so shaped?

The WP page for this: Kidney dish provides a few pictures, and notes that bowl" is a shallow basin with a kidney-shaped footprint". I immediately imagined that they must be equipped with some ambulatory prowess, and wondered if such were kept under lock and key when they were not being used. Perhaps, the mundane "base" might have sufficed. The article notes that the dish is shaped so it can be held against a curved surface such as a torso, and collect blood more efficiently than a dish with straight sides could. Fine. But I had long thought that some shapes for dishes render them more stable, and less inclined to tip over, and others are inherently unstable. The kidney dish, I had long-thought, was one of the former. Can anyone throw some light on this? I believe that dishes with circular bases are the most unstable. But have there been any experiments with dishes being pushed, jolted and tilted to see which shape is the most stable? Myles325a (talk) 07:28, 4 May 2016 (UTC)

AFAIK (which isn't a reliable source) the shape is indeed from that of blood-letting bowls, where the concave edge made them useful for catching the most blood (or whatever else is falling out of a patient). The rest is convention and the fact that even when a kidney-shaped bowl isn't useful for a particular task, it isn't a drawback and it allows them to stack with the other kidney-shaped bowls. Instrument trays though are rectangular, as they make better use of space on a small trolley.

I think the shape is based on the upper rim, not the base, and that stability doesn't enter into it. Stability is mostly about the steepness of the sides (shallow sides make a narrow base and that does reduce stability). Shallow sides also make for more splashback. Nursing 101 of course explains why not to try to catch vomit in any shallow dish-shaped bowl. Andy Dingley (talk) 10:32, 4 May 2016 (UTC)

Here is a circular bowl (with a circular base) that is very stable. http://www.academy.com/shop/pdp/ruffin-it-stainless-steel-dog-bowl-018946848p--1 It depends on more than just the footprint. 196.213.35.146 (talk) 10:36, 4 May 2016 (UTC)

OP Myles325a back live. Thanks number man, this lovely image is that of a dog bowl, where the rim curves inward, not straight up or outward, probably because that set up helps contain the food within the bowl as the dog wrestles with and devours it. Is this configuration more or less stable than bowls with rims which curve outwards, or is it all the same? I would opt for the former because, while the centre of gravity remains the same as with the inward-pointing rim, the outward-pointing rim is inherently more unstable. For example, the dog could suddenly press down on the outward rim tipping the bowl towards him. This cannot happen with the inward-pointing rim bowl. I would hazard a guess and say that while the centre of gravity’s position is important to stability, it is NOT the be all and end all of the matter. The inward-pointing rim bowl has its mass distributed over a smaller area, making it harder to upset. Myles325a (talk) 04:04, 5 May 2016 (UTC)

Any rigid body resting on a flat surface is in a stable state if its Center of mass lies over its base area. Round vases, bottles, dishes etc. with circular bases are not inherently unstable but vary in their critical tippling angles $A$ which measure how far they can be tipped to one side and still return to their upright position.

$A=arctan(r/h)$

where $r$ is radius of the base, $h$ is height of the center of mass. A tall bottle with a small base has small $A$ and is only weakly stable since a slight tilt will topple it; conversely a symmetrical solid Cone object that has large $r$ with small $h$ has large $A$ so it is difficult to topple. A kidney dish has largest $A$ (is least liable to topple) when it is empty because filling the dish raises $h$. The dish's resistance to toppling is least ($A$ is small) in the direction of its short dimension. The characteristic curvature in its long dimension makes almost no difference to its overall stability. AllBestFaith (talk) 12:01, 4 May 2016 (UTC)

OP Myles325a back live. Thanks, AllBestFaith, you have done more to address this quest ion than anyone else. Leaving aside the maths, it is obvious that (say) a vase with a circular base and with a low perimeter is more stable than one with the identical base but with a tall perimeter, as per your bottle example. Note that both vases have the same centre of gravity. Thus this thought experiment shows that centre of gravity is not the only feature influencing stability. But my query is not directly concerned with the matter of how rims affect stability, which has been settled by your answer, it is more concerned with how the layout of the base affects stability. So we could assume for all cases under consideration, the rim is straight up, and its height is derived as a function of the area of its base. (And of course, they are all made of the same material Myles325a (talk) 04:19, 5 May 2016 (UTC)

OP Myles325a – This just in. AllBestFaith, you note that “A kidney dish ...(is least liable to topple) when it is empty... Let me see if I have got this right. You would intuitively expect a full bottle to be more stable than an empty one, as its weight makes it harder to tip over. But then, a dish with a big base relative to its low perimeter might well be inherently unstable. Think of carrying a frying pan full of water. The greater the area of the pan’s base, the more likely it is that the water will begin to slosh about and spill. But these considerations are perhaps sidetracked by questions of fluid dynamics. If we put sand rather than water in the pan, it would be far more stable. Myles325a (talk) 04:35, 5 May 2016 (UTC)

A kidney dish has a flat bottom so shouldn't tip over because of instability. --TammyMoet (talk) 14:05, 4 May 2016 (UTC)

The answer to the question is this sentence in the article: "The shape of the dish allows it to be held against the patient's body to catch any falling fluids or debris." ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:15, 4 May 2016 (UTC)

I remember being in 6th grade or thereabouts and reading about medical and surgical practice. When I read about "kidney dishes" in the hospital I assumed it was designed for a surgeon to deposit an excised kidney in, and wondered if there were specific named dishes for each organ which might be removed. ("Nurse! Bring me a spleen dish, an appendix dish and a gall bladder dish!") Edison (talk) 16:03, 4 May 2016 (UTC)

Shocked doctor: "No, no nurse, I said Remove the patient's SPECTacles" AllBestFaith (talk) 22:54, 4 May 2016 (UTC)

I've always rather fancied getting some kidney dishes to serve kidneys in. Soup goes in a soup bowl, gravy in a gravy boat, so why shouldn't kidneys get their own dish? DuncanHill (talk) 22:59, 4 May 2016 (UTC)

What kind of dish are you going to use for the spotted dick, and will you put two appropriate vessels of Rocky Mountain oysters in a bag along side? DMacks (talk) 23:29, 4 May 2016 (UTC)

OP Myles325a rides again. Thanks, Edison; this is kinda a cross twixt an eggcorn and a mondegreen. I rem the Walrus and the Carpenter poem from “Through the Looking Glass”. A couple of lines from there go: “To talk of many things: / Of shoes--and ships--and sealing-wax--...For many years I thought it was “ceiling wax”, which I assumed was some special compound like fine plaster to coat the rosette around a pendulous light. It is pure felicity that a misconception like that should occur via Lewis’ work, which plays extensively with such constructions.

I think that I have nutted out a bit more of this problem. A circle is the most compact way of containing a given area. So it is the most unstable. If you take the same area (a hamburger patty) and spread it out (a sausage) it becomes more stable. The kidney dish is a more stable way of organizing the base area because it spreads the outer circumference of the dish. So a U is more stable than a O. And if we twisted one side of kidney dish to face the opposite direction, it would form an S, and that would be even more stable. If you do not think this is plausible, think of a circular base of a radius of (say) 10 centimeters. Now imagine taking that circular base and extruding it so it forms a long rectangle that is only a centimeter wide. Is not that shape very stable. Now imagine taking this long rectangle and making it into a loose spiral that has a radius much larger than the original circle. This kind of base would be very stable indeed. It becomes impossible to think of how it could be tipped over. Myles325a (talk) 05:26, 5 May 2016 (UTC)

And to top it off, we can fill in the needlessly unused spaces in that long spiral and make it a circle, so it is most stable of all. :) ... I have no idea, I really don't ... :) Wnt (talk) 21:06, 5 May 2016 (UTC)

Symbol & in Html

what is the html code to get this symbol &  ???--Ip80.123 (talk) 09:56, 4 May 2016 (UTC)

&. See more at &#Computing. PrimeHunter (talk) 10:25, 4 May 2016 (UTC)

Also, see ampersand, which is what the symbol is called. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:29, 4 May 2016 (UTC)

Recovering data from Iphone soaked in salt water

This question would apply to Iphones or other digital devices with memory chips which are recovered after being immersed in water or recovered from a wet environment. Two 14 year old boys went fishing in the Atlantic ocean in a small boat and were lost at sea. The boat was found months later and hundreds of miles away complete withe their celphone, which had been soaked in salt water. A news article said it might be impossible to recover any stored data such as videos, voice memos, notes, GPS locations, or numbers dialled, since it was claimed 'the entire phone had to be functioning" to recover data. It is said to be a "newer model" Iphone, and might have the same passcode issue as the terrorist iphone which the FBI had someone hack. My basic question is, why couldn't the Mobile DDR be unsoldered, cleaned, and downloaded to a backup storage, so there is no possibility of deleting the contents from too many attempts at the passcode, and then brute force attempts be made in cracking the passcode. If the cloned chip is erased after 10 attempts, reload the source data and try the next 10 sequential passcodes. This could easily be automated, and 10000 attempts should take way less than a day. Are there other chips which store data on an Iphone which make it different than any other Iphone of the same model fresh in the box? In other words, does the memory chip only function with its fellow chips from the original phone? Is a "recent model Iphone" passcode restricted to 4 digits, or can it be longer and more varied? How well sealed are present-day chips against ingress of water into the plastic encapsulation? I would expect there are many cases where someone wants to retrieve data from memory chips which have been immersed in saltwater, and there are reports of data recovery after "days" of immersion in saltwater. In this case it was "months." Are memory chips tested at all for maximum data survival while immersed? Edison (talk) 16:39, 4 May 2016 (UTC)

This and This imply it is not as simple as you make it out to be. --Jayron32 16:45, 4 May 2016 (UTC)

I didn't "make it out to be simple." I just asked why if was impossible even in principal.Is it possible to unsolder a chip from a circuitboard in an Iphone, if you have the training and tools? Having achieved that step, the question is whether the data on the chip can be transferred to another memory chip. Someone found a digital camera which had been dropped in the ocean 4 years earlier, and had no trouble recovering all the data, after a good cleaning. In criminal cases where a phone was buried or tossed into the bay, or if loved ones were drowned in a boat accident, small plane crash or hurricane, someone might be interested enough to pay someone to do even painstaking steps to recover data. The news story said that one would have to power up the original Iphone to recover the data, and I'm asking if that is correct. Is the Mobile DDR chip that much more fragile in saltwater than the camera chip which was downloaded after 4 years in the ocean? Edison (talk) 17:11, 4 May 2016 (UTC)

As I read this question, Edison is specifically asking about iPhone, rather than about a generic modern digital device at large. Per the publicly available iOS Security Guide, "Every iOS device has a dedicated AES 256 crypto engine built into the DMA path between the flash storage and main system memory, making file encryption highly efficient." Clearly, a highly-capable and well-trained, well-funded organization could have the equipment to carefully disassemble the hardware... but even if you were able to remove the nonvolatile storage hardware without damaging it - and if the hardware was undamaged by exposure to the natural elements - the contents are strongly encrypted. One would not be able to trivially decrypt the content, and even with a brute-force attack, it would be very difficult to recover any data. The nature of strong encryption implies that one would not even be able to locate the data that was securely encrypted: the user's protected data would be completely indistinguishable from empty space on the file-system unless you could break that encryption. Nimur (talk) 18:47, 4 May 2016 (UTC)

Beyond what Nimur has said, you seem to be confusing different things. As the article you linked to says Mobile DDR is a form Dynamic random-access memory i.e. Volatile memory. While there has been some observed Data remanence#Data in RAM in certain forms of DRAM [15] for minutes or hours, and longer if cooled, none of these are likely in the scenario you outlined or really most scenarios with a phone. Perhaps the only likely would be if the phone is still on and you think there's something useful in the RAM. However it's very risky since you risk damaging something and the the earlier link makes me wonder if you even have any hope of recovery (most phones now use mobile DDR derived from DDR3 or may be even DDR4 AFAIK).

In truth even if you could recover, the difficulty of access etc means it's going to be very rare anyone attempts to recover data from mobile DDR. Remember you have to do it quick before the data is no longer recoverable probably in a cooled environment.

Recovering data from the non volatile flash memory storage is a different matter. But as has been said by Nimur, recovering the data is of limited utility if you can't decrypt it. And depending on the design of the phone, decrypting it may be very difficult if all you have is the flash memory content and not whatever was in some other chip which may store part of the decryption system. You will have to bruteforce the whole key rather than simply the password, passphrase, PIN or whatever.

Nil Einne (talk) 19:59, 4 May 2016 (UTC)

So while it was recently proven it might not be "IMPOSSIBLE" to crack an iPhone's security features, it took, probably THE most well resourced intelligence agency in the world several months to get into one phone, for reasons of, literally, national security. We still have NO idea how they actually did it. For all we know it might have included a secret deal with apple, or even an apple "mole". It seems unlikely anyone would be in a similar position and willing to spend the same amount of resource to get some data from the phones of 2 people who were confirmed lost at sea. Vespine (talk) 01:46, 5 May 2016 (UTC)

The FBI isn't an intelligence agency. Also, they have stated publicly in broad terms how they got in; they bought an exploit from an Israeli cracking firm. Obviously it's up to whether you believe them, but the story is very plausible. There are dozens of these firms that specialize in finding exploits. Basically all software is buggy and full of undiscovered security holes. For instance, here's the latest massive security hole in widely used software, just revealed the other day. --71.110.8.102 (talk) 05:58, 5 May 2016 (UTC)

I'm not certain if precisely who they bought it from was ever revealed see e.g. [16] [17] [18]. However who they paid seems to be mostly beside the point. And Vespine's comment suggests some confusion about what the FBI actually did. As far as we know, all they seem to have done is gotten around the artificial time and trial limitations allowing them to keep trying PINs fairly quickly, which is what they wanted Apple to do for them [19] [20] [21] [22] [23]. This exploit is largely irrelevant to what's proposed by Edison namely simply removing the flash chip. I don't think we know precisely how it works, there was some very early speculation here [24] but what the FBI have since disclosed suggests there's no physical modification of the phone needed. Since the problem seems to be at least partially that it's likely some components are damaged, I guess you could move the flash and security chip to another phone of the exact same design if they were working fine. And this probably won't work partially because of software. In that case you may need an exploit similar to the San Bernadino case. But that's a lot of ifs. Nil Einne (talk) 09:34, 5 May 2016 (UTC)

"71.110.8.102:The FBI isn't an intelligence agency.". The opening line of our FBI article: The Federal Bureau of Investigation (FBI) is the domestic intelligence and security service. I admit I have not researched in depth exactly how it was cracked, my point was: it was. Vespine (talk) 23:16, 5 May 2016 (UTC)

Cookies in a Tin - Nitrogen?

High-quality (sometimes imported) cookies (any language variant) are sometimes sold in a tin that is sealed with a plastic-like or cellophane-like sealing material, which is easily ripped off when opening the tin. I remember that, in the past, occasionally when such a container was opened, there was a slight hissing sound. That would have indicated that the tin had been evacuated and that the cookies were vacuum-packed to ensure freshness. (Is there a pun to vacuum-packing? How can nothing be packed in a tin? Well, the cookies are not nothing, just packed in nothing.) Sometimes these days there is no sound on breaking the seal, but the cookies are fresh several months after the tin was sold. Presumably the original reason for evacuating the tin was that oxygen can react with the cookies and cause them to become stale. If there is no sound on breaking the seal, that suggests that the tin wasn't evacuated. My question is: Are the cookies preserved by packing them in nitrogen or carbon dioxide? I can see that any reaction with carbon dioxide would be slower than with oxygen, and with nitrogen would be even slower. (While monatomic nitrogen is an extremely reactive gas, diatomic nitrogen is about as inactive as a gas can be that isn't truly an inert gas, because the dinitrogen triple bond is one of the strongest bonds known in chemistry. That is, those nitrogen atoms really "want" each other.) When a tin of cookies or other food is sealed, is nitrogen used to ensure freshness? Robert McClenon (talk) 16:49, 4 May 2016 (UTC)

This article looks interesting. As does This video. --Jayron32 16:52, 4 May 2016 (UTC)

These how it's made-type videos are like Qoyaanisqatsi, but without the moralism. Asmrulz (talk) 23:03, 4 May 2016 (UTC)

In fact, it is more important to keep out moisture and light - though an inert gas may be used in some cases (it rather depends on the type of biscuit). 81.132.106.10 (talk) 17:20, 4 May 2016 (UTC)

Jayron32 deliver good references as usual. Lets consider the question of whether a cookie tin could have a full vacuum inside. An old standard science experiment to demonstrate the pressure of the atmosphere, around 14 pounds per square inch, was to boil water in a 1 gallon metal can with a screw-top, made of steel of similar thickness to a cookie tin. Once the small amount of water in the bottom was boiling good, and the can was full of steam, the heat was shut off and the cap was screwed on. Immediately the can was crushed nearly flat, as the steam condensed and there was no pressure inside to counter the atmospheric pressure outside. The lamer experiment today uses an empty unsealed Coke can with stem inside which is crushed when inverted i a pan of cold water. But similar to your experience, I have purchased ground coffee in a plastic cylindrical container, with a metallized plastic seal on the top. When the plastic is punctured, air hisses INTO the can and the concavity of the seal is reduced. Maybe they ship it with some of the air removed, or with some of the air removed and nitrogen replacing it.Maybe the ground coffee resists the crushing of the container. I wouldn't expect cookies to resist can crushing at all. If the gas in it is nitrogen, though, I don't see the point of the reduced pressure. To save nitrogen? Edison (talk) 17:35, 4 May 2016 (UTC)

Stem? DuncanHill (talk) 23:02, 4 May 2016 (UTC)

Highly unlikely a tin could withstand full atmospheric pressure with a vacuum inside. The cookies would crumble because of the pressure changes too. But a small pressure differential may be created if the cookies are put in the tin at a high altitude or slightly warm. Water vapour present in the tin may be absorbed by the cookies, creating 1 kPa or so underpressure before the air in the tin is dry.

If any preservative gases were added to the tin it should be mentioned on the packaging. At least, in Europe it should be mentioned. Look for statements like "packaged under a protecting atmosphere" or whatever it is exactly in english or your language. Have a look at packaging gas and E number, in the range 938–949. PiusImpavidus (talk) 19:24, 4 May 2016 (UTC)

Yes, a hissing sound is associated with reduced pressure packing but inert gases can be used in combination. Where there is no hissing for cookies containers I hazard a guess that its argon and its E number may not appear. Being mono-atomic it changes the partial pressure of water vapor ensuring the cookies (or whatever) stay dry (desiccates bacteria too). The best answer would be to get it from the horses-mouth. The packaging will have either a web address or customer care-line number, consumer services department or something. Google the company to find their contact us details and send them an email. When I worked in industry we often received these sort of odd-ball inquires and we answered them the best we could. It was viewed as an important part of PR. So I can guarantee you, that you will get a reply.--Aspro (talk) 21:10, 4 May 2016 (UTC)

Note that the hissing sound during opening doesn't necessarily mean it was stored under reduced pressure intentionally. Either it might just have happened to be in a slightly different air pressure environment when it was sealed than when it was opened, or the act of opening the package may itself increase the volume, and thus decrease the pressure, as pulling the cork out of a wine bottle does. StuRat (talk) 14:58, 5 May 2016 (UTC)

The hissing also seems to be evidence the container was well sealed, and presumably helps reinforce the customer's trust in the hygiene of the product. This is also OR, but I note StuRat's idea above, though reasonable, suggests we should see an outflow of air frequently from products packed at sea level (especially since so much comes by ship). Yet I've never seen an outflow of air, because everyone associates it with botulism beans and such. In good, out bad, and that seems reflected in the marketplace. Wnt (talk) 21:10, 5 May 2016 (UTC)

Somme river flooding

Hello,

How often and how severely does the Somme river in France flood? Where can I find data on this? — Preceding unsigned comment added by 140.233.173.140 (talk) 20:46, 4 May 2016 (UTC)

Our article Somme (river) has statistics for the past few decades, and the French article fr:Somme (fleuve) has more data. From the latter: « Les crues, quant à elles, sont rarement importantes, sauf en cas de saturation de la nappe phréatique, comme ce fut le cas en avril 2001. » - approximately translated "Floods, on the other hand, are rarely significant, except when saturation of the water table occurs, as was the case in April 2001". Tevildo (talk) 23:18, 4 May 2016 (UTC)

So, for example, around how often do significant floods occur? (significant as in may have caused significant damage to a medieval town) I'm a bit confused by the data. — Preceding unsigned comment added by 140.233.173.140 (talk) 01:02, 5 May 2016 (UTC)

This has a timeline (page 6) and this discusses things to some extent. I googled inondation somme Thincat (talk) 08:28, 5 May 2016 (UTC)

May 5

Extinction vs. evolution of defense mechanisms

Why is that some groups of animals manage to evolve defensive mechanisms against predators and other threats, while other animals (sometimes from the same taxonomic rank) do not evolve anything and become extinct? Is it about population size and slow rate of predation? Thanks. 93.174.25.12 (talk) 14:24, 5 May 2016 (UTC)

It's virtually impossible to say with certainty exactly why similar scenarios can turn out differently in evolutionary history. Lots and lots of factors come into play, and we are not really able to do controlled experiments for these scenarios. But yes, you basically have the right idea. I'll say a little more about the factors and give you some refs that will help you think about this issue: Selective pressure e.g. through predation comes in various strengths. Too low and it won't have much effect, too high and the species is wiped out right away. Allee effects can come into play for very small populations, and in that scenario, random chance can play a big role too. Alternative stable states discusses a little bit about how random fluctuation can lead to different outcomes in ecological models. Apparent competition provides another way of looking at this. If a predator P preys on species A and B, then the dynamics of A and B are actually similar to when A and B compete for a single resource R, because of the predator's prey switching. This gets in to top-down vs. bottom-up control of ecosystems, by species at different places in the food web, see here [25] for a brief description of those effects and here [26] for a scholarly review article. Finally, note that in the case where one predator P eats one species A almost exclusively, they will have strong pressure to not eat all of A, because if they did, P could go extinct too. So that's a very broad overview of the forces that influence whether species persist in a sort of Red Queen race or whether one or more go extinct. If you have further questions or would like more specific references let me know and I'm happy to provide more info. SemanticMantis (talk) 14:43, 5 May 2016 (UTC)

(ec) Note that extinction isn't just caused by predation, there's also a loss of habitat, food supply, climate change, disease, etc. One way in which predators can wipe out a species is if an invasive species is introduced which is far more capable than the prey, not giving the prey the time they would need to make massive adaptations. Species limited to islands with no natural predators are particularly vulnerable, like the dodo. On the other hand, if a predator in the same environment slowly evolves more capability to hunt the prey, the prey can evolve an ability to survive that predator at about the same rate. StuRat (talk) 14:45, 5 May 2016 (UTC)

Evolution is the summation of random mutations that enables a life form to compete. If they find that their Ecological niche is suddenly changing due to say climates changes or/and other predators or animals that are better at competing for the limited food supply moving in, then they may not be able to evolve quickly enough to adapt. This goes for other things as well. Take Microsoft. In the early years it was a predator. Now it a grown to be a slow moving giant dinosaur, leaving other more adaptive critters to nip at it ankles take away the food it needs, because they have better evolved and can do so more quickly.--Aspro (talk) 14:56, 5 May 2016 (UTC)

• Relevent here is Survivorship bias. Much of people's misunderstanding about evolution comes with the notion that, while mutations are random and capricious and arbitrary, only mutations which have "survived" are evident long enough to leave a significant record, so we have the mistaken sense that evolution has a purpose or a goal or makes living things "better". --Jayron32 16:10, 5 May 2016 (UTC)

I am actually suspicious that a species can go extinct through lack of predation. The dodo is a classic example, though some now say it has been misrepresented. If members of a species do not periodically make a run for their lives, will they continue to be able to run? Etc. Of course, the dodo never actually became too weak to move ... it just reached a point where it couldn't handle a sudden change for the worse. A species facing many predators is already at worse, and can't be so greatly surprised. I even wonder if a prey species tends to evolve a top speed that just barely ensures the predators will keep getting fed with its weaker members, though that would be in a sense a pretty remarkable extreme of altruism, already a controversial concept. But I have not really seen anything about this. Wnt (talk) 21:02, 5 May 2016 (UTC)

Hey @Wnt: do you mean you suspect lack of predation can cause extinction? Resource competition models show how species can go extinct with no predation. All you need is an uptake rate that's faster than the supply rate. Tilman's R*_rule_(ecology) is relevant here, see also [27] [28] [29]. But there's no predator even in the picture there. To get at the notion of lack or too little predation, you'd want to have a fairly stable system with say one predator, two consumers, and one resource, then show that removing the predator can cause one of the consumers to go extinct. In concept this could be investigated with microcosms, but I don't know as much about that. For the theory, check out my colleagues Chesson and Kuang (2008) [30] or maybe some of their other work [31]. I don't know if they have this specific scenario covered, but I suspect they do. Ecological modeling his hard, evolutionary modeling is hard, food web modeling is hard, and very few people have been bold/crazy enough to try to understand all three interacting. There are some simulation models out there that get pretty complicated, but depending on your epistemic stance, those don't really tell us anything about the real world. Then again, depending on your epistemic stance, no model no tells us anything about the real world ;) SemanticMantis (talk) 21:58, 5 May 2016 (UTC)

@SemanticMantis: Great answer - it is indeed hard. Even reality seems like a bad model, to be honest. For example, in the case of the Lake Guri howler monkeys, the long-term effect of losing a predator in the abstract is overwhelmed by the effect of huge extremes in population that occur immediately. It's like you have to ask what would happen if overgrazing yields a new equilibrium over many years that is not different from the old equilibrium, then would the predator's absence also cause specific changes in the former prey? It's not even really a coherent question, I guess. At least, I'm not sure how to frame it properly. Wnt (talk) 22:45, 5 May 2016 (UTC)

Percent deviation from additivity

What is the quantitative expression associated to the verbal phrase +/_x % deviation (expansion or contraction) from the addivity of volumes in water ethanol or water salt/sugar solutions?--85.121.32.1 (talk) 15:47, 5 May 2016 (UTC)

Could it be a fraction whose numerator include the difference between the volume of the mixture V and the volumes of the two components V1 and V2 and the denominator equals the sum V1+V2:

$\%\Delta V={\frac {V-(V_{1}+V_{2})}{V_{1}+V_{2}}}100$?--85.121.32.1 (talk) 15:52, 5 May 2016 (UTC)

Medical Satire

Thinking of putting this suggestion up to Wikipedia:WikiProject Requested articles but would like your comments first, as the editors here seem to have both feet on the ground.

Something, I have had simmering on my back burner for years, is that Wikipedia doesn't have an article on Medical Satire yet. There is a lot of it about – one could even say that it is a chronic pandemic. It is my (personal) belief, that it has a slow incubation period, starting in the early twenty’s (at the same time when protection of one's parental antibodies wains) with signs an symptoms only becoming manifest in the mid-thirties. Until such time, that medical science can come up with a effective treatment for this malady, is there any Quacks Doctors/nurses/radiographers/hospital porters/morticians/ etc., that can help me to put such an article together?--Aspro (talk) 17:13, 5 May 2016 (UTC)

You're talking about this [32] sort of thing, right? Here's [33] [34] some refs to get you started, lots of refs therein too. I would not have guessed the genre could trace its roots back to the 17th century! SemanticMantis (talk) 18:31, 5 May 2016 (UTC)

I don't think Wikipedia needs an article about every combination of literary form and subject matter. Is there something about satire of medicine that makes it more than the sum of its parts? -- BenRG (talk) 19:15, 5 May 2016 (UTC)

Tiltwinged and thrust vectoring airliners

Thrust vectoring says it's not currently used on commercial aircraft. In practice, what are chances of a commercial airliner with a sort of tiltwings that tilt to a desired angle and thrust vectoring engines for better control of the angle of attack? Costs aside, my understanding is that it would reduce (or eliminate) the possibility of stalling, diving, flat spins and other undesirable aerodynamic effects, so that even in case of pilot error (like Pulkovo Aviation Enterprise Flight 612) the proper airflow could be restored. Brandmeister^talk 20:38, 5 May 2016 (UTC)

If such things as tiltwings, [tiltrotor]]s, variable-sweep wings, variable-incidence wings and thrust vectoring were considered cost efficient, we would already have operational commercial aircraft with one or more of these features. Since we don't, I have to assume that the cost (in regard to money, weight and added complexity) of adding such features outweighs the benefits of them. WegianWarrior (talk) 21:04, 5 May 2016 (UTC)

I know nothing about this, but I had an impression the Bell Boeing V-22 Osprey was not a particularly safe aircraft. Does the benefit of having all those fancy features available for emergencies really outweigh the odds that something going wrong with them will cause an emergency in the first place? Wnt (talk) 22:33, 5 May 2016 (UTC)

A predecessor of the proposed Boeing 2707 supersonic transport was planned to have had "swing wings" (variable geometry), but they made the aircraft too heavy and the final design had a delta wing rather like Concorde. Alansplodge (talk) 22:44, 5 May 2016 (UTC)

Could we be in a black hole right now?

Could we (Earth and visible universe) be inside a black hole right now and since the beginning of times? --Llaanngg (talk) 22:35, 5 May 2016 (UTC)

See Black-hole_cosmology. Some people find this idea convincing, others don't. I'm not even sure if it's a falsifiable claim or not. SemanticMantis (talk) 22:46, 5 May 2016 (UTC)

This exact same question was asked just last month. Vespine (talk) 23:08, 5 May 2016 (UTC)

An antidepressant

I just found out by accident that citalopram, a rather popular antidepressant, is a salt of Hydrobromic Acid. Good Lord, it is a very strong mineral acid. To have it in the GI tract on a daily basis... Isn't it dangerous? --AboutFace 22 (talk) 22:42, 5 May 2016 (UTC)

Salt (i.e. table salt) is a salt (chemistry) of hydrochloric acid. The neutralization of an acid into something more neutral is what makes a salt a salt. Wnt (talk) 22:47, 5 May 2016 (UTC)

There a comprehensive list of adverse effects here. There are not any GI track specific effects though, only related to SSRI discontinuation syndrome. --Llaanngg (talk) 23:23, 5 May 2016 (UTC)

What happens if long enough rope is on earth?

49.135.2.215 (talk) 01:26, 6 May 2016 (UTC)Like sushi