Wikipedia:Reference desk/Archives/Science/2015 February 10

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February 10

water use comparison:production of gallon of milk vs gallon of soy milk vs gallon of almond milk

I'm wondering what comparisons of all 3 types are available. thanksRich (talk)`

Well, there's a great deal of inefficiency in converted plants into animals, so the cow's milk will take the most. I can't comment on whether soy milk or almond milk would be next.

Not interested in rice milk, coconut milk, cashew milk, etc. ? StuRat (talk) 00:24, 10 February 2015 (UTC)

All of those sound equally wretched. Are there any honest reviews of their taste to be found? ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:41, 10 February 2015 (UTC)

I've tried most of them. They're not exactly the same as cow's milk, but they aren't bad. They seem to be selling well, so others must agree. (They also keep much longer than cow's milk, and anyone who ever drank sour milk will appreciate that.) StuRat (talk) 05:30, 10 February 2015 (UTC)

I've switched from cow's milk to almond and almond/coconut milk (we usually get "Almond Breeze"). While they definitely don't taste like cow's milk, they really aren't supposed to. So instead of saying "Do these fake milks taste like real milk" you should be asking "In what part of my diet can cow's milk be replaced with almond (etc) milk?"...something doesn't have to taste the same to taste good - and that's what we have here. When I occasionally drink cow's milk, the difference in flavor is very noticable - but still not objectionable. Baseball bugs should refrain from calling something "wretched" without trying them. They taste just fine...and they are VASTLY better for the environment than cow milk. The big open question for me is whether these plant-based milks can be used in cooking. So far, our very limited experiments say "Yes"...but I could easily imagine that not working out too well in every case. But for the three uses I have for the stuff (to dunk cookies into, to pour onto breakfast cereal and to whiten my coffee), the plant-based stuff works 100% perfectly as a substitute. Almond breeze also makes an almond/honey milk...I quite like it, but my wife didn't.

So much for the personal story...HERE are some results from what seems like a fairly careful analysis. It shows that all of the plant-based milks are at least 20 and as much as 50 times less "impactful" on the environment than cow's milk. It shows that coconut milk is better then almond which is better than soy. Personally, I find pure coconut milk to be too far from the 'mouth feel' of dairy - but I like the flavor - hence my choice to use the coconut flavored almond - or the pure almond. Sadly, that study didn't cover rice milk. I found it to be a little bland - so again almond/coconut wins for me. Coconut/almond chocolate milk is to die for...in my mind, the flavor is hugely superior to cow's milk.

So try a bunch of them - don't judge them for 'realism' versus cow milk, that's not the idea here and if you approach the problem with that mindset, they'll all fail. But if you're open to a new flavor...try a bunch of them before you settle on a couple of favorites.

Another observation I have is that cow milk doesn't taste the same everywhere...the stuff we get here in Texas tastes *WAY* different than the milk I drank in the UK. This again speaks to that "realism" thing.

SteveBaker (talk) 14:53, 10 February 2015 (UTC)

They did indeed seem to market all those products as milk substitutes initially. Putting "milk" on the label, putting it in similar half-gallon containers, and making it look like milk demonstrate this. But I agree that they can go beyond mere substitutes.

As far as cooking, cow's milk has the issue of foaming up and boiling over. Do those other "milks" do that ? If not, that sounds like a definite improvement. StuRat (talk) 15:04, 10 February 2015 (UTC)

The figures would likely depend significantly on where the products are being produced. It will also depend on what you're counting. For example, if cows are raised and fed mostly on a pasture which is mostly watered directly by the rain, are you counting that water? What do you do about the significant contamination of the water supply that may result from the cow effluent? (This can be a significant problem BTW, see e.g. Water pollution in New Zealand [1] [2]). I know a number of people here hate the concept of Virtual water, I personally don't go so far, but I would say it has major limitations and does greatly oversimplify matters (similar to the concept of food miles for example). Nil Einne (talk) 01:39, 10 February 2015 (UTC)

strain guage load indicator

what is the use of strain guage load indicator and how is it used — Preceding unsigned comment added by 117.222.121.206 (talk) 08:46, 10 February 2015 (UTC)

See Strain gauge. The gauge measures strain, the relative movement of parts of a mechanical system under load. Tevildo (talk) 09:19, 10 February 2015 (UTC)

And using the strain reading and knowing the material involved, the forces acting upon the object can be inferred. Thus a strain gauge is one way to determine those forces, as in a strain gauge scale: [3]. StuRat (talk) 14:58, 10 February 2015 (UTC)

Temperature profiles

I'm looking for datasets (e.g. CSV) for
a) earth atmosphere (like in File:International Standard Atmosphere.svg)
b) world oceans (like in File:THERMOCLINE.png)
temperature profiles. May anyone help?--Kopiersperre (talk) 13:08, 10 February 2015 (UTC)

NOAA is the place to go for this sort of thing, I think you can (in principle) make graphs like those from the data here [4]. Track up a level here [5] to get an overview and search, and also look here [6]. I don't think they deal in CSV these days - the format is very cumbersome and space-inefficient for large data sets. One format they hand out is netCDF, and some instances of that are basically wrappers for HDF5 - if you are interested in this sort of thing, I recommend you learn how to handle those formats. Both can be converted to CSV (with a loss of structure and metadata) if necessary. SemanticMantis (talk) 14:33, 10 February 2015 (UTC)

I would like to have a something like a global mean. This shouldn't be too big for CSV. Thanks for the links!--Kopiersperre (talk) 14:51, 10 February 2015 (UTC)

Why did?

1) Why did natural magnetism of planet Earth always determines the possibility of the existence of all substances on the planet Earth, and could also determines the possibility of creating these substances in the natural environment of the planet Earth, so did that means the fact of physics that in case of changes of the natural magnetism of planet Earth many substances really cease to exist in the natural environment of the planet Earth, and other substances could not be created in the new conditions of the planet Earth?

2) Who discovered the Law of conservation of energy in this form of physical-mathematical formulas |F| = |-F|?--83.237.214.220 (talk) 15:54, 10 February 2015 (UTC)

I added numbers to your Qs:

1) The Earth's magnetic field supposedly protects the lighter elements and molecules (including water vapor) in the atmosphere from erosion due to the solar wind. This in turn protects the oceans, which might evaporate into space if there was no magnetic field. Without our current atmosphere or surface water, life probably would not exist on Earth. StuRat (talk) 16:03, 10 February 2015 (UTC)

"supposedly". Do you believe otherwise? 217.158.236.14 (talk) 16:44, 10 February 2015 (UTC)

It's instructive to note that Mars has had no magnetic field whatever for at least the last four billion years - yet it's believed to have had surface water as recently as two million years ago. This might reflect the amount of time that this theoretical atmospheric stripping and subsequent ocean evaporation might take...but I think this shows that it's not obviously true that we owe our atmosphere and hydrosphere to the magnetic field. Venus also has an almost non-existent magnetic field - and despite being even closer to the sun, has an exceedingly dense atmosphere - which also makes it hard to reconcile the idea that you need a magnetic field in order to have a dense atmosphere. Venus has no oceans, but that's because of the insane amount of heat caused by its runaway "global warming" problem.

So, I agree with User:StuRat that this explanation for the importance of the Earth's magnetic field is probable, a quick glance at our neighboring worlds suggests that it's not necessarily the case. SteveBaker (talk) 17:09, 10 February 2015 (UTC)

Yes, the Atmosphere_of_Venus and Atmosphere_of_Mars are good to look at, and show that a strong magnetic field is not a necessary condition for an atmosphere. It's a little bit unclear what precisely the OP is looking for, so I'll say this simply: We can say with near certainty that our planet's atmosphere is affected by its magnetic field. We can say with near certainty that atmospheric escape would be greater if the field were weaker. We can say with near certainty that our atmosphere would be different if Earth never had a magnetic field. It is nearly impossible to say exactly what our atmosphere would be like without a magnetic field. SemanticMantis (talk) 18:11, 10 February 2015 (UTC)

No, but it's theory, which can't be directly tested, so I don't want to refer to it as if it were a proven fact. StuRat (talk) 16:45, 10 February 2015 (UTC)

Dude, That is not what theory means in science, see scientific theory. A theory is not a hypothesis, but both can and are commonly tested. You should know better. I apologize for the emphatic text but this is important and you shouldn't be spreading harmful misinformation. The Theory of gravity is "just a theory", so is the Germ theory of disease. Both of these have been extensively tested, refined, and extended over the course of many years. I don't know much about Earth's_magnetic_field, but there are plenty of citations in that article. Additional info and references at Atmospheric_escape#Significance_of_solar_winds. I don't think there are is any serious contention about the fact that the Earth's magnetic field helps protect the atmosphere from solar wind. SemanticMantis (talk) 17:00, 10 February 2015 (UTC)

I didn't say no theory or hypothesis can ever be tested, only this one. As for gravity, it isn't exactly settled, either. Are gravitons real ? Is space-time really warped ? How do we combine gravity with the other forces and quantum dynamics to create a theory of everything ? StuRat (talk) 21:09, 10 February 2015 (UTC)

Did not you think that the properties of all substances in the nature of the planet Earth is always determined by the natural magnetism of planet Earth?--83.237.205.179 (talk) 17:05, 10 February 2015 (UTC)

The properties of substances isn't greatly affected by the nature of the magnetic field. Hydrogen and oxygen react to make water, which freezes at zero degC no matter where in the universe it happens to be - with or without a magnetic field. There are a very, very few cases where it does matter...but generally, no. What we're talking about with atmospheric and hydrologic stripping by the solar wind on planets without a magnetic field, we're talking only about which substances are present at the surface of the planet - not what the properties of those substances are. SteveBaker (talk) 17:16, 10 February 2015 (UTC)

2) Our Conservation of energy article has a "History" section that describes the discovery of the law - you can't really attribute it to any one person. The ancient Greeks (notably Thales and Empedocles) wrote about this idea and asserted it to be true. Galileo also believed in it and did some simple experiments to try to demonstrate it. Leibniz produced the first modern mathematical formulation...and at least a dozen others have had a large contribution to this concept. I'm not sure about |F|=|-F|...I have no idea what that's trying to say, or who said it. SteveBaker (talk) 16:59, 10 February 2015 (UTC)

How can be consider the Law of conservation of energy in this physical-mathematical formulation |F| = |-F| in the scientific nuclear physics?--83.237.205.179 (talk) 17:05, 10 February 2015 (UTC)

|F| = |-F| is a trivial consequence of the definition of | |. When we use that operator we're saying that only the magnitude of the quantity is relevant, not its orientation. But in a conservation law the orientation (direction of a vector or sign of a scalar) is vital, so | | does not belong anywhere near it. I hope this helps. —Tamfang (talk) 20:31, 11 February 2015 (UTC)

Mathematical value of the module in mathematics is always expressing the inverse proportionality of mathematical values, in this case |F| = |-F| be proving the mathematical identity (equality) of inversely proportional physical-mathematical units (values).--83.237.243.175 (talk) 15:49, 13 February 2015 (UTC)

How did the organs evolve?

When multicellular life got started, what organs were formed first? Count Iblis (talk) 21:28, 10 February 2015 (UTC)

I am assuming you are talking about multicellular animals, not multicellular organisms in general. For multicellular animals it is very likely that the first ones - similar to modern sponges - had differentiated cell types but did not have differentiated organs; see Parazoa. However, this is not known for sure, as the precambrian fossil record is quite sparse. Some of the earlies lineages of multicellular animals with differentiated tissues (see Eumetazoa) that survived until modern times are jellies, comb jellies, corals, etc.; it would probably be safe to assume that the first multicellular animals with differentiated tissues were similar to some of those, and possessed similar body plan and organs. Dr Dima (talk) 22:25, 10 February 2015 (UTC)

For some it was the mouth it was the mouth, for you it was the anus. μηδείς (talk) 02:30, 11 February 2015 (UTC)

You might like to check out the physiology of salps and other Tunicates. Of course we don't know exactly how the first organs arrived, but these critters are fairly ancient, and fairly primitive/basal. Medeis can't help but obscure helpful links in weird jokes, but I think the idea is that you might want to learn a bit about Evo devo as well. SemanticMantis (talk) 13:19, 11 February 2015 (UTC)

It's not really a matter of organs forming first, but gradually becoming more differentiated. In a very primitive organism the single cell is skin, digestive tract, muscle and sensory organ. With multicellularity, eventually "inside" and "outside" became distinguishable (ectoderm, endoderm) with mesoderm soon to follow (surrounding what you might call internal pockets of sea (coelom), protected spaces where gametes were released and the precursor of urine could be processed, usable hydrostatically as the first intimation of a skeleton. And each of these became more and more subdivided and specialized so that each activity had its own organ. But take any given enzyme from any given organ and there's a good chance you can find some relative in a protozoan. The activities are more separated than created. Wnt (talk) 15:19, 11 February 2015 (UTC)

There's also some fun stuff that is analogous to organs inside organisms, like the behavior of Dictyostelium_discoideum (note the "altruistic" death without reproduction of the stalk members), or even the sub-units within a superorganism. SemanticMantis (talk) 16:10, 11 February 2015 (UTC)

What is the evolutionary advantage in learning to control the anal sphincters?

^ 140.254.70.33 (talk) 23:59, 10 February 2015 (UTC)

Have you ever tried finding a mate while you're constantly crapping? Or tried to hide from a keen-nosed wolf? A regularly filthy ass and legs will attract flies, which have no problem breeding in your skin. That can outright kill, or just make sex even more difficult. Not a problem underwater or in the sky, but land-based furry critters should literally not shit where they eat. InedibleHulk (talk) 00:43, 11 February 2015 (UTC)

Somehow, cattle seem to do just fine with flies constantly buzzing around their fecal covered anuses. StuRat (talk) 00:46, 11 February 2015 (UTC)

They have the wherewithal to lift their tail first and aim as far away as they can (not very). And that tail can keep the flies away from ground zero. If they shit in their sleep, it wouldn't be so tidy. InedibleHulk (talk) 00:54, 11 February 2015 (UTC)

As usual StuRat is talking crap. Mulesing might be a bit of fun for him, I doubt the animal regards it as 'just fine'. Greglocock (talk) 04:30, 11 February 2015 (UTC)

Perhaps somebody needs to explain to you the difference between sheep and cattle ? Sheep tend to have thick covering of wool, which seems to be the cause of the problem your talking about. I was talking about cattle, which do not have a thick covering of wool. See the difference ? StuRat (talk) 04:40, 11 February 2015 (UTC)

I'm sure you are an expert on cow's anusses, but gthids guy appears to differ https://books.google.com.au/books?id=PbEWJrEtECIC&pg=PA323&lpg=PA323&dq=maggots+cattle&source=bl&ots=eQkvrA4hCM&sig=_dUy2bJUxWQ5I8bAxwF53w7KVzo&hl=en&sa=X&ei=v_naVP-CDo_W8gW564KIBQ&ved=0CDQQ6AEwBA#v=onepage&q=maggots%20cattle&f=false

Greglocock (talk) 06:43, 11 February 2015 (UTC)

Or, to put that another way, https://books.google.com.au/books?id=PbEWJrEtECIC&pg=PA323 —Tamfang (talk) 20:21, 12 February 2015 (UTC)

The mighty yak might feel slighted by your oversight, were he not mighty. Also, did you know there's a SugarRat on Wikipedia now? You two should hook up. InedibleHulk (talk) 05:12, 11 February 2015 (UTC)

1) Limits the spread of disease, especially if they defecate in an area far from where members of their species eat or drink.

2) Make it harder for predators to track them.

3) If they are predators, makes it easier for them to sneak up on prey.

Burying feces helps on all counts. However, I don't go along with the idea that the evolution of anal sphincter control has any effect on mating success, since any species which lacks anal sphincter control will also not care if potential mates smell like feces. Heck, even though dogs have such control, they still seem to enjoy the smell (and even taste) of feces. StuRat (talk) 00:49, 11 February 2015 (UTC)

Whatever the personal kinks, survival itself helps a lot with getting laid. Even if you're not dead yet, most potential mates should be able to spot the flaws in your setup. Not for my kids, she'll say. InedibleHulk (talk) 00:57, 11 February 2015 (UTC)

Also, a bunch of crusted dung over the old gene socket doesn't help the physical probabilities. Sure, she could keep it cleaner, but that's just less time spent on eating, hiding and raising kids. An ounce of prevention is worth a pound of cure. InedibleHulk (talk) 01:00, 11 February 2015 (UTC)

Primates are also pretty notorious for using feces as a weapon... and not just in the Special Housing Unit. For that they need to be able to produce it on demand. Also I imagine that there are some advantages to not crapping on the tree trunk you have to climb down, or which a predator could climb up. Admittedly all rampant speculation... not sure how you'd answer a what if like this with any confidence. Wnt (talk) 01:34, 11 February 2015 (UTC)

It's very easy. InedibleHulk (talk) 01:36, 11 February 2015 (UTC)

Sloths' defecation habits are a bit hard to understand. They climb down the tree (very slowly), defecate, then climb back up (slowly again), vulnerable to predators when on the ground. Wouldn't it be a lot safer to just let fly from the tree ? StuRat (talk) 01:39, 11 February 2015 (UTC)

Isn't that exactly how Ohio State students do it? μηδείς (talk) 02:28, 11 February 2015 (UTC)

Maybe if you made a habit of going to the bathroom. Sloths can go fifty days before thinking they shouldn't have had Mexican food (average of "only" sixteen, though). They'd make nature's worst drug mules, even moving at airspeed. InedibleHulk (talk) 01:48, 11 February 2015 (UTC)

Though, considering they eat between poops, they have to go for that long walk about once a week. Still, not bad. As long as they don't do it on the same day, every week. That's asking for trouble. (My apologies for presuming animals used calendars.) InedibleHulk (talk) 01:53, 11 February 2015 (UTC)

As for dogs and cats, their population and diversity explosion is directly tied to their adoption as pets, and that's hugely contingent on their housebreaking skills. Without a vigilantly puckered butthole (WARNING: contains butthole), man's best friend and woman's pretend child would be confined to the academic section of the Internet, instead of driving the bus. InedibleHulk (talk) 03:25, 11 February 2015 (UTC)

It is wrong to assume that because an organism has a trait, that that trait confers an evolutionary advantage. Everyone repeat after me: "Not all traits are adaptive traits." The better way to phrase this type of question is "Is there an evolutionary advantage?" SemanticMantis (talk) 14:47, 11 February 2015 (UTC)

That depends. If it's a trait that must exist, like eye color (even if it's just the pink eyes of an albino), then you're correct, every animal must have this trait (provided that they have eyes, of course). But an optional trait, with a cost associated with it (in this case increased weight and therefore slower movement due to retained feces) is never going to evolve unless it confers some advantage. Now, conditions could change, such that a trait, once evolved, is no longer advantageous, but that's a different matter. StuRat (talk) 15:15, 11 February 2015 (UTC)

No, it doesn't "depend". One more time, repeat after me: Not all traits are adaptive traits - there's no equivocation, no caveats, and no exceptions. Your notion of "optional trait" has no usage in evolutionary biology. There is also no such thing as a necessary trait. Genetic drift is a real thing. Some traits confer advantages, some confer disadvantages but also advantages, we often describe this in terms of Trade-offs. But some traits have no measurable affect on reproductive success and hence no real affect on evolution. Figuring out how this all pans out is very difficult, and people usually study it for several years before they go around saying they can explain the fitness benefits of a certain trait. Sometimes it's very context dependent, and fitness will depend on the concentration of other traits in the population, as in the now classic example of the mating habits of the Common_side-blotched_lizard, which use a sort of round robin mating strategy. Finally, even eye color can affect reproductive success through sexual selection. You can speculate about advantages of sphincter control all you like. I get it, it's fun to speculate about fitness, morphology, and behavior. But it's just speculation until you find a reference to a peer-reviewed study, or publish one yourself. SemanticMantis (talk) 16:05, 11 February 2015 (UTC)

So it's your contention that animals may have evolved the ability to control defecation despite it having absolutely no evolutionary advantage ? Wow, just wow. And are you also denying that carrying feces around has a disadvantage (which then would require a corresponding advantage) ? StuRat (talk) 16:14, 11 February 2015 (UTC)

The point is the OP is asking the wrong question. It's always a bad idea to ask the wrong question, since it can easily lead to the wrong answers, and at the very least, understanding why you're asking the wrong question can often be more important than knowing the answer to the question. Nil Einne (talk) 18:09, 11 February 2015 (UTC)

Back to advantages: I believe some animals defecate when being chased, in the hopes that it will distract the predator long enough for them to escape. StuRat (talk) 16:14, 11 February 2015 (UTC)

The emergency defecation is a means of lessening the weight load of the fleeing prey and of disgusting the predator. μηδείς (talk) 04:38, 12 February 2015 (UTC)

And, of course, the skunk has taken its ass to a whole new level of anti-predator adaptation.

Here's an academic paper on whether holding it in is an evolutionary advantage for humans. InedibleHulk (talk) 23:41, 11 February 2015 (UTC)

At least for modern humans, it's quite an advantage, since it allows us to use sewage treatment systems (and before that, latrines and septic tanks), which have greatly reduced the incidence of many infectious diseases and increased life expectancy dramatically. (Although perhaps we would all wear diapers by now, if we all had fecal incontinence.) StuRat (talk) 04:46, 12 February 2015 (UTC)