Wikipedia:Reference desk/Archives/Science/2017 May 18

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May 18

End mill

Can End mill be used to drill holes? The article says "milling bit can generally cut in all directions", so presumably the answer is yes, but I just want to double-check.

(The second half of that quote is "though some cannot cut axially", so it's clear that not all end mill can drill. I'm wondering if any end mills can drill at all.) Scala Cats (talk) 02:13, 18 May 2017 (UTC)

With huge limitations if they have one of their frontal cutting teeth extend over the middle/rotary center of that tool (as you can see on the picture of the article). They are meant to slowly dive into material for just a few millimeters so they can start cutting a Groove, a pocket or alike inner forms without the need for more complicated, timely methodes like milling a path "down" with a slope. --Kharon (talk) 08:32, 18 May 2017 (UTC)

• What are "holes"? Do you need them accurately to size? Good surface finish? Deep and narrow?

An end mill has three obvious shortcomings over a drill bit: it has no ability to centre or guide itself, it has limited swarf clearance upwards and it may not remove any metal from the centre of the bit, when used axially (so can't simply be plunged).

End mills are used for holes, but usually by milling them. An end mill smaller than the finished hole is moved in a circular path, milling a progressively deeper hole as a pocket. Compared to the forces involved with a twist drill, you need a more rigid machine to gain a similar rigidity in the tool (drill forces are largely balanced). Also the "drilling" speed will be much slower. But it does work, and if you're CNC milling on a machine that doesn't have rapid or automatic tool changing, it's done a lot. Andy Dingley (talk) 17:35, 18 May 2017 (UTC)

What happened in AHA guideline in 2015 regarding to the definition of children age?

Till 2015 the definition of child for CPR, was 1-8 year, but in the end of 2015, AHA published updates and there (see p.11) it redefined it as "Children- Age 1 Year to Puberty "). The thing that interesting is that for all updates there are explanations except of that significant update (it may be a difference of 4 and more years...) that doesn't have explanation. Do you know what is the explanation behind this new definition? 93.126.88.30 (talk) 05:40, 18 May 2017 (UTC)

One of my trainers said it was because it's easier to assess. Not so much that it is important to get the "right" details for someone who is 10 depending on how developmentally mature they are, but that is more efficient to gauge a victim by appearance than to ask the age and saving time in this situation is an actual benefit. DMacks (talk) 21:43, 18 May 2017 (UTC)

Homogenous packaged, pre-cooked food

Dogs and cats are usually served homogenous packaged, pre-cooked food, and they get all their nutrition from that. Meanwhile, humans, afaik, have to eat various foods in order to have complete nutrition. Is there a homogenous, packaged, pre-cooked, nutritionally complete, safe (as in not inducing acute illnesses) food product for humans who don't mind eating the sane thing every day? Can humans eat dry kibbles? Or should they eat something like wet dog food with more vegetables? 140.254.70.33 (talk) 13:19, 18 May 2017 (UTC)

There isn't - because pretty well all humans do mind eating the same thing every day. The nearest you would find would be some of the emergency rations issued to the military, or used in famine relief - but even those have some variety to them. There would be no particular problem producing something containing everything needed by the human body - but I can't see anyone actually doing it as there wouldn't be a market for it. Wymspen (talk) 13:27, 18 May 2017 (UTC)

Actually, the product does exist — nutraloaf — and there is a market for it — prisons. But the above is correct that it's not likely to be viable or available as a product in a standard grocery store. See also the humanitarian daily ration. — Lomn 14:11, 18 May 2017 (UTC)

Soylent_(meal_replacement), is probably the closest to what you're looking for. Their marketing tries very hard to imply that you could use it as a 100% substitute for all food. They don't actually make that claim, though. (And I'm personally very dubious about that company's safety record.)

Some emergency rations also claim to be nutritionally complete, so I suppose instead of stocking them in your bomb shelter or lifeboat, you could just eat them regularly. I doubt your doctor would recommend it, though.

ApLundell (talk) 14:19, 18 May 2017 (UTC)

Oh, of course Soylent did not invent the concept of a Meal_replacement, there are other brands. They're just not as aggressive in their marketing so far as implying that you could give up real food forever. ApLundell (talk) 14:27, 18 May 2017 (UTC)

(EC) I actually regularly give my mum a meal replacement drink (in addition to normal food, she has had low weight issues in the past and for various reasons can be quite slow at eating), and it specifically says it's not intended as a total diet replacement. Actually two different brands of pretty much the same thing say that. Our article also notes that in the EU there's actually a regulated difference although this is only for weight control products and they have to say they can't be used for more than 3 weeks without medical advice. So it actually quite a different marketing strategy. However I don't believe Soylent is the only one with such a strategy, maybe just the first. There seems to have been a wave of them recently perhaps inspired by Soylent, e.g. Huel, Mana (drink). I'm not even sure if Soylent is universally the most popular, considering the possible problems of shipping food from the US. See also [1]. I believe there are also some products which predate these, which may be used with feeding tubes or people on a Liquid diet but these are generally very expensive (I've seen commentary from people comparing the price of Soylent etc to the price of these products) and aren't aren't marketed to the general public. They also aren't necessarily recommended long term (especially very long term). Nil Einne (talk) 14:57, 18 May 2017 (UTC)

I think I encountered "Ensure" a long time ago (one of the ones on that list) and didn't find it unpalatable at the time, though its goal of providing calories was not really useful to those of my particular shape. But ever since Guantanamo officials became famous for delivering it rectally (recap) I'm afraid I would look at it like drinking an enema. Their former habit of running commercials with a pseudo-military cartoon character talking about "nutrition in charge" did NOT help with this. Thanks to Gitmo their brand is pretty much irredeemably tarred, even if not by any fault of their own... Wnt (talk) 16:14, 18 May 2017 (UTC)

Since no one has mentioned it so far, the other area that one gets meal replacements is in the care of persons who have difficulty eating normally. For example, cancer patients undergoing chemotherapy often have digestive problems that limit what they can practically consume. A number of brands exist to sell liquid meals (e.g. shakes) to ill people who have trouble eating and/or digesting solid food (e.g. Prosure, Fresubin, etc.). They aren't generally marketed as a permanent solution, but they do aim to provide complete nutrition for a while. Dragons flight (talk) 14:46, 18 May 2017 (UTC)

Huel, which was mentioned above, say on their site that a tiny percentage go 100% (i.e. no other food). Henry^Flower 19:04, 18 May 2017 (UTC)

I had a tracheotomy a while back and I was on liquid glurge (technical term) for several weeks in the aftermath of that, initially by tube and then when the trachy came out that was all I could 'eat'. I think the deal was I was supposed to drink 6 small cartons a day, in practice I couldn't manage half that. Greglocock (talk) 19:53, 18 May 2017 (UTC)

I just found an unused carton, it says it is NOT recommended as a complete replacement for food.Greglocock (talk) 02:15, 19 May 2017 (UTC)

Since you're from Australia this made me check something I'd been thinking when replying above and quickly found the relevant Food Standards Australia New Zealand regulation [2]. That makes this (and what Vitaplan/Complan packets say) unsurprising. The standards for a formulated meal replacement in Australia and New Zealand require that they "specifically formulated as a replacement for one or more meals of the day, but not as a total diet replacement" and represent themselves as such. I couldn't find any regulation covering a total diet replacement, it's possible it doesn't exist since it's only something that can be given under medical supervision so there's no need for a specific food standard. Nil Einne (talk) 11:43, 19 May 2017 (UTC)

The North American Soylent labels also have words to that effect. "While not intended to replace every meal, Soylent can replace any meal."ApLundell (talk) 13:09, 19 May 2017 (UTC)

Which makes sense from a legal view, since replacing a meal is a very different claim from being able to replace every meal. Missing a single micronutrient could leave you open for private lawsuits or government action for failing to live up to the standard. Much better to imply it while disavowing it! Matt Deres (talk) 14:42, 19 May 2017 (UTC)

I don't think this is quite the same thing though, since I've never seen people promote products like Vitaplan or Complan as a total diet replacement. I mean I'm sure there are some people who do it, but I doubt this is actually a significant market strategy by the manufacturers. These products are recommended by medical professionals to help when people are underweight or otherwise having problems getting sufficient nutrients, (actually that's why I started giving them to my mum), so I doubt that the manufacturers are particularly interested in muddying the waters by pursing such a marketing strategy anyway.

Also notably these products just call themselves formulated meal replacements or similar with the above warning. They never claim they can replace any meal like Soylent does. I guess Soylent's legal team believes there was some advantage to the wording (probably because it's easier to show a diet appears to be harmful than it is to find out why it's harmful), but I don't see how a product which claims it can replace any meal can lack a micronutrient. Clearly that product is not replacing the meal where you would get that micronutrient so there are some meals they cannot replace.

(To put it a different way, my reading of the FSANZ related wording, from long before I ever heard the Soylent one, is that it says these products can replace some meals, they may not be able to replace all meals, so you do so at your own risk; whereas the Soylent wording seems to say this product can replace all meals, but we just don't want to say it to make it harder for you to sue us.)

Nil Einne (talk) 14:07, 21 May 2017 (UTC)

Some comments:

1) Liquid meal replacement can never be complete, as they would need a significant amount of fiber, making them too thick. Also, some of the minerals seem to settle out of solution. Shaking just before drinking and then adding some milk or water to get the last bits out may help here.

2) New micronutrients are being discovered every day, so an approach of just giving you all the vitamins, nutrients, and micronutrients you need might fail. But, if a wide variety of foods are included, you are likely to incidentally include micronutrietns we don't know we need yet.

3) Allergies make the approach of including "a bit of everything" likely to cause issues.

4) Individual variations in people mean that we don't all have identical dietary requirements, and our requirements may vary from time to time. For example, during a woman's period, she may need more iron to replace that which was lost. Cravings can get us to eat foods with nutrients we need, but they can also misfire and get us into trouble.

5) Some food needs to be eaten fresh, to get the max nutritional benefit. Something more like a freshly made smoothie would be better here, than something that's been on a shelf for months.

6) However, even with the above problems, the current diet in the US and some other places is so dismal that this would still be an improvement for most people.

7) Many of the above problems would also apply to pets, and we have seen some customization of pet foods for overweight, juvenile, elderly, and gluten-intolerant animals (whether they really exist or not). StuRat (talk) 23:27, 19 May 2017 (UTC)

, particularly for number 1. Not that I'm personally a fan of the idea, but as I understand it including per our article and [ [3]], older versions of Soylent did actually meet the US recommended intake for fibre. The amount was lowered later, not primarly because it made the product easier to drink but because it was believed the fibre content was contributing to gastrointestinal symptoms, particularly gassiness. This means some people add fibre, again it's still drinkable.

One factor is that many recommended intakes, don't actually differentiate between soluble and insoluble fibre, although they may say you should get all fibre from your diet not supplements, which is complicated when your diet is basically a special kind of supplement. [4] [5]

While [6] does offer some guidelines, the fact that these aren't part of common recommendations means you should treat them with caution. Of course even if these guidelines are right for a general diet, it's not clear if they make sense for a liquid diet anyway even assuming a liquid diet is healthy [7]. (That and [8] + [9] suggests the insoluble fibre content in Soylent can be a little low by some recommendations.)

P.S. Have you ever tried something like Metamucil? I've heard from people who have and while some may say it's undrinkable this isn't generally because it's too thick. Nil Einne (talk) 14:30, 21 May 2017 (UTC)

Yes, "too gritty" may be a better description. In any case, that much fiber in your drink is undesirable. StuRat (talk) 19:23, 22 May 2017 (UTC)

Do any wild/feral animals know what traffic lights or walk signals mean?

Because they know what the light means and not because they just follow the people or learned that when cars stop on busy streets they don't start again for awhile or detect the light changing mechanism's ultrasound or magnetic fields or something like that. Sagittarian Milky Way (talk) 14:33, 18 May 2017 (UTC)

Not as a rule, but on Jamaica I was told that some wild goats did not even observe the traffic signals, but had even learned to request a green light at on-demand traffic crossings. --Stephan Schulz (talk) 14:47, 18 May 2017 (UTC)

That's pretty cool. Sagittarian Milky Way (talk) 17:53, 18 May 2017 (UTC)

At what point, SMW, are you going to stop using the desks for validation of every random thought that enters your head? --Jayron32 14:49, 18 May 2017 (UTC)

Hatting this. Wnt (talk) 16:17, 18 May 2017 (UTC)

And I have removed the hat. The question was asked here, no where else, so there's no reason why a response to the question shouldn't be posted here. Nil Einne (talk) 02:30, 19 May 2017 (UTC)

Well in that case I'll repeat the comment I put above the hat: SMW asked an interesting question and got an interesting answer, and this meta stuff belongs ... somewhere else. But if you insist on having it here I should say, how much would we do with the Refdesk if people didn't ask us questions? Especially when they're interesting. Wnt (talk) 11:44, 19 May 2017 (UTC)

I am sorry Jayron, I did not intend to imply that I want people to tell me they know what traffic signals mean to validate my random thought. I don't know if any such smart animals exist or not and would not be reduced to tears if no one could find any evidence. I am aware that unless it's very conditioned an animal wouldn't give a fuck what the traffic laws are if it thinks the traffic is light enough it can cross without too much trouble. I have made this clearer in the question. Sagittarian Milky Way (talk) 17:53, 18 May 2017 (UTC)

Who would notice? People do however notice cats that ride buses. [10], [11], [12]. Also ditto Jayron. Aspro (talk) 15:06, 18 May 2017 (UTC)

I've seen a pigeon ride a train. And get off the next stop. Sagittarian Milky Way (talk) 17:53, 18 May 2017 (UTC)

the reason that pigeons ride on trains as as passengers, may be due to them beginning to fill the niche left by the extinction of the Passenger pigeon Aspro (talk) 21:36, 18 May 2017 (UTC)

Obey is maybe not the right word, but ravens certainly know how traffic lights work. Cheers ✦ _hugarheimur 15:30, 18 May 2017 (UTC)

I agree. Know that they'll likely get harassed by traffic if they cross on red, not obey. (or whatever color a stop light looks like to their eyes) Sagittarian Milky Way (talk) 17:53, 18 May 2017 (UTC)

There are plenty of humans who don't obey traffic signals either. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:37, 18 May 2017 (UTC)

Original research, a couple of weeks ago in London, but I saw an urban red fox cross a busy road at some pedestrian traffic lights. He didn't wait for the little green man though. Alansplodge (talk) 17:15, 18 May 2017 (UTC)

Some years ago, before the great Bristol urban fox die-off (a distemper outbreak), there was a particular junction (Zetland / Gloucester Road) where foxes could often be observed crossing. They also showed regular behaviour of waiting for the pedestrian light before crossing. There's no indication that they had any relation to the signals, but they obviously recognised stationary traffic on this busy road (even late at night) as being regular and worth waiting for. If you were lucky, you could even wait alongside one - they were very urban foxes. Some of the local students were quite feral though. Andy Dingley (talk) 17:40, 18 May 2017 (UTC)

In general, there are two types of animals which cross roadways: (1) the quick; and (2) the dead. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:58, 18 May 2017 (UTC)

I am getting increasingly frustrated by people leaving answers to ethology-based questions when they apparently have little grasp of the way such studies should correctly analysed and interpreted. Please make yourselves familiar with Morgan's Canon and Occam's razor as a starting point.

In answering the OP question, I would want to see a video/study in which the animal is proven to be watching the lights. In all the studies I have seen, the animal (mainly ravens) are observing the consequences of the lights changing (traffic moving, pedestrians walking) rather than watching the lights. It would also be interesting to know whether the animals can actually perceive the wavelengths emitted by the lights - see Trichromacy.

As stated in the goat example, the goats do not observe the lights themselves. The have probably learnt to press a button by stimulus enhancement from other goats or humans. DrChrissy ^(talk) 23:33, 18 May 2017 (UTC)

Goats will certainly press buttons. Goat behaviour is such that they will press, prod and butt at anything they can reach. They can often open gates and pen doors simply by undirected persistence, and eventually finding the latch. Andy Dingley (talk) 08:19, 19 May 2017 (UTC)

It is known, birds sometimes use cars to crack walnuts. The birds observe an intersection. When traffic lights change, not know if they really watch the signal, they place the nuts on the road. Cars crack them with the tries. The next signal phases, the bird come and pick the cracked nuts.[13] Not only humans are using tools.[14] But they are trageting someting else than the human. Not really knowing what they are doing, but songbirds still hear and playback.[15] --Hans Haase (有问题吗) 19:18, 19 May 2017 (UTC)

I believe the story about birds using cars to crack walnuts is a myth. The birds that are said to show this behavior are California crows. There is no doubt at all that these crows drop walnuts on roads to crack them. But the story about cars results from the fact that when people see them doing this, they are usually driving along the roads and only notice what happens in front of them. When I lived in Davis, California I bicycled daily along the roads where this happens, and it was clear to me that the nut-dropping behavior had no relation to the presence of a car. Looie496 (talk) 14:40, 21 May 2017 (UTC)

The truth is, the bird utilize the cars for cracking the nuts, but as the video shows, the birds remain on the road when the pedestrian lights turned red. Means, they do not really understand the traffic light, but found out, there's a schedule or periodic change. The moving traffic made them leave the road. In a suburb on a hill the next city to my birthplace, birds have been seen, waiting in a tree for the bus, taking a ride uphill on the bus' gunwale. The bus is slow on this small winding road. Later gliding downhill as flying more easily. --Hans Haase (有问题吗) 17:46, 21 May 2017 (UTC)

Both variants of this behaviour exist.[16] Crows have been recorded placing nuts on the road and then eating the contents after a car has crushed the nut. (I make no comment about the timing of this behaviour other than it is obviously advantageous to the crow to use busy streets rather quiet streets.) This can easily be explained by Trial and error learning by a single crow and this behaviour then spreading by Cultural transmission in animals. The second variant, dropping the nuts off a bridge, can be explained in exactly the same way. DrChrissy ^(talk) 19:42, 21 May 2017 (UTC)

condensed climate chart

I love reading about various locales on Wikipedia and checking out their climate charts, but the full spectrum of information available in a climate chart is a little too much to digest. I mostly just focus four items: average high, average low, average precipitation, percent possible sunshine.

Is there a some kind of metric/formula that condenses the monthly climate data of a given location into a single number? As in, a single number that measures how "comfortable" the place is for people? Not too hot, not too cold, minimal precipitation, maximum sunshine, etc.

Is there a website that I can easily look up this metric on a map, say for vacation planning purposes? Scala Cats (talk) 19:57, 18 May 2017 (UTC)

See Degree day#United States. This measure used to be used, and I assume is still used, by Places Rated Almanac. Loraof (talk) 21:48, 18 May 2017 (UTC)