Wikipedia:Reference desk/Science

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

Want a faster answer?

Main page: Help searching Wikipedia

   

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

April 24

What came first, the chicks or the chicken?

What came first, the chicks or the chicken?

Do women lay an evolved egg (which is internal and better protected), or, do chicken lay an evolved ovum (which has its own nutrients, and can be laid anywhere and forgotten about)? What evolved from what? --Llaanngg (talk) 01:38, 24 April 2015 (UTC)

Explained here. Count Iblis (talk) 01:58, 24 April 2015 (UTC)

Mammals (including humans) evolved from egg-laying animals, although not specifically from chickens. StuRat (talk) 04:24, 24 April 2015 (UTC)

Indeed monotremes still lay eggs; only the other mammals evolved vivipary. Note that vivipary has evolved many times in many different groups of organisms, even full-fledged hemotrophic vivipary (i.e. sustenance from the maternal blood supply) in sharks with yolk sac placentas. A cruder example is Limnonectes larvaepartus, a frog that bears tadpoles that apparently eat feces and one another while inside the mother's body. Wnt (talk) 13:06, 24 April 2015 (UTC)

Minor correction: from vivipary - "When considering squamate reptiles in particular, there is a correlation between high altitudes or latitudes, colder climates and the frequency of viviparity. " - Viviparous reptiles are a little different than viviparous mammals in terms of the means and mechanisms of reproduction, but they are still considered viviparous. SemanticMantis (talk) 15:15, 24 April 2015 (UTC)

• Modern amniotic vertebrate eggs arose with the amniota 330 million years ago, flying dinosaurs have been around since the Jurrasic, and the land and waterfowl (Galloanseres) have been around since before the K/T event. The genus Gallus has been around since the mid-Pleistocene at least. Since we use the term chick nowadays to refer to all baby birds, they have been around since before the dinosaurs went extinct, the modern domesticated chicken only since the end of the last ice-age, and the hard-shelled egg since the late Carboniferous.

What are the signs that there's a sinkhole beneath the ground you're on?

Are there telltale signs that there's a sinkhole below the ground you're on or the building you're in? --108.52.38.146 (talk) 02:48, 24 April 2015 (UTC)

watch here. Count Iblis (talk) 03:05, 24 April 2015 (UTC)

Not until it's rather too late, when the ground starts to sink. Sometimes there's enough warning to evacuate before total collapse, sometimes not. To avoid this risk, you'd want to use ground-penetrating radar (dragging a device that looks like a lawn mower back and forth across the surface in a grid pattern), especially if you are in an area with karst topography. StuRat (talk) 04:21, 24 April 2015 (UTC)

Here's what happens when you don't realize you are walking on a sinkhole. μηδείς (talk) 20:20, 24 April 2015 (UTC)

Have a look at Detection & Warning Signs of Imminent Sinkhole Collapse --Aspro (talk) 21:54, 24 April 2015 (UTC)

We had a sinkhole forming around a manhole above a sewer. The manhole kept getting lower, and there were holes along the sides going all the way down to the sewer. When we first sounded the alarm, they just patched over the holes with asphalt, but I knew that was no good. Soon enough the holes were even larger. Fortunately, they then repaired it correctly. StuRat (talk) 23:37, 24 April 2015 (UTC)

meteorology vs aerology

What is the difference between meteorology and aerology? --IEditEncyclopedia (talk) 13:13, 24 April 2015 (UTC)

Meteorology is a part of aerology—atmospheric sciences. Ruslik_Zero 13:43, 24 April 2015 (UTC)

"Aerology" is an old term that is rarely used any more. It had two main usages. First, it was the U.S. Navy's term for meteorology in general. (The Navy tends to have their own way of doing things.) Second, it was the study of the free atmosphere, above the boundary layer. In the second sense aerology is part of meteorology, not the other way around. Short Brigade Harvester Boris (talk) 19:49, 25 April 2015 (UTC)

April 25

Drilling holes and magma

If you drill into the Earth deep enough, will you eventually hit magma? Will this work anywhere on the planet? Malamockq (talk) 18:43, 25 April 2015 (UTC)

One issue is that if you drill toward very hot material, the drill bit stops working - see Kola Superdeep Borehole. Another issue is that rock in the mantle (geology) is not really liquid but "plastic" in nature, and only becomes magma when it moves up enough for the pressure on it to be relieved. In theory, an open borehole would relieve the pressure, so does that make it magma? But you couldn't make an open borehole because the "plastic" rock would push in on it too much to keep it open, I think. (ought to research that further) But if you use "your mind's eye" to scout for "true liquid" under the ground, then there's nothing guaranteed short of the outer core, which is molten iron and hence not really magma either. Wnt (talk) 18:55, 25 April 2015 (UTC)

If you could drill such a hole, then the magma would cool, thicken, slow, and finally solidify, as it rose through cooler surrounding rock, so I don't think you'd get a volcano, if that's what you meant. A volcano requires a large magma chamber close to the surface, from which it can then erupt. StuRat (talk) 19:07, 25 April 2015 (UTC)

A practical method is described here. Count Iblis (talk) 19:39, 25 April 2015 (UTC)

See previous discussion that discussed the challenges of drilling into shallow magma chambers beneath volcanoes. Mikenorton (talk) 21:39, 25 April 2015 (UTC)

Soooo, the answers to the actual questions are yes and yes, in case that wasn't obvious from the above verbiage. I am assuming what the OP really wants to know is is there molten rock under us no matter where we are on earth. See Magma#Migration (magma comes from the mantle or crust of earth). Richard-of-Earth (talk) 20:22, 26 April 2015 (UTC)

April 26

Aircraft propeller design

My traditional idea of a propeller blade is something like this. However, some modern aircraft have propellers that look like this or this, where the angle of the blades looks (to a non-expert) to be hopelessly wrong, more like a paddle-wheel that would drive the aircraft sideways. What is the reason for this change? 81.152.230.173 (talk) 01:52, 26 April 2015 (UTC)

See Propeller (aeronautics)#Feathering. -- ToE 01:57, 26 April 2015 (UTC)

Even the first photo's props could be feathered, notice the cylindrical escutcheon (or casing if you must) around the root of each blade. That houses the feathering mechanism.Greglocock (talk) 02:45, 26 April 2015 (UTC)

Your photos are of a C-130 (or variant thereof); and either a TBM or a Meridian turboprop (I can't tell from this angle). All of these aircraft use a constant-speed propeller: the pitch of the propeller blade varies with power setting in order to keep the rotation speed constant. For more on the theory and practice of these propellers, see the section on transitioning to complex aircraft (Chapter 11) in the Airplane Flying Handbook, or read about constant speed propellers in the Pilot's Handbook of Aeronautical Knowledge. Constant speed, variable pitch propellers exist because they enable the engine to operate at a maximally efficient RPM no matter how much power is needed for any specific flight configuration. Conversely, fixed-pitch props waste power - and therefore, fuel - by running the engine in an inefficient configuration (low RPM) when low power is required. In effect, the airfoils (blades) of a fixed-pitch prop are slipping through the air for almost all operating conditions except at one particular peak-efficiency power setting.

Also note that a variable pitch propeller need not be driven by a turbo engine: for example, the Super Decathalon is a piston-powered Citabria whose powerful engine drives a constant speed propeller; the Cessna 182 is a conventional general aviation aircraft whose piston engine drives a constant speed propeller. Constant speed propeller is one among three required elements of a "complex" aircraft, as defined by the FAA: a single-engine land aircraft must have flaps, retractable gear, and a constant speed propeller to qualify as "complex."

Nimur (talk) 03:13, 26 April 2015 (UTC)

The photograph of your traditional idea of a propeller shows a radial, reciprocating engine. The other two photographs show turbine-propeller engines. The former type of engine tends to be much older than turbine-propeller engines. The design standards for aircraft in that era allowed the pilot to manually feather the propeller of an engine that suffered a complete loss of power, even though it was well-known that a "windmilling" propeller on a failed engine generated a very large amount of drag, especially when the aircraft was flying at high speed. The design standards in that era didn't contain any incentive for prompt, automatic feathering of the propeller following an engine failure. In these engines, there is no need for the pilot to feather the propeller when the engine is being shut down at the end of a flight.

The design standards for modern aircraft, and especially those with modern turbine-propeller engines, contain a significant penalty (in terms of payload) for any multi-engine aircraft that relies on the pilot to recognize an engine failure, identify which engine has failed, and then manually feather the propeller on that engine. There is a strong incentive for designers to equip the engine and its propeller with sensors and pumps to automatically coarsen the pitch or feather the propeller whenever the engine is delivering less power than it should. Pilot action is not required for these propellers to feather at any stage of flight, including the end of a flight when the engine is being shut down. As a consequence, the propellers on these engines feather automatically whenever the engine is shut down. Even when one of these engines is installed on a single-engine aircraft, the automatic pitch-coarsening and feathering functions are retained. The two photographs you have supplied of turbine-propeller aircraft show aircraft that are stationary on the ground with their propeller blades in the position they automatically move to whenever the engines are shut down. Dolphin (t) 06:25, 26 April 2015 (UTC)

Bum hair

Hi,

I am curious about why evolution has decided to keep hair on our anal region. I can't imagine it serving any particularly useful service, and it certainly has a detrimental affect in terms of cleanliness.

I've read stuff like The Ancestor's Tale, and have a reasonable lay-person's perspective on evolution.

I know that most seemingly-inexplicable traits (massive antlers, peacock tails, etc) are down to sexual selection, and that it's often best to assume sex-sel plays a role. But I can't see how that affects our bottoms.

I can understand how apes-humans lost their hair, and that keeping hair on our heads and beard makes some sense (heat-loss, usually exposed). I can understand that perhaps hair on genitals might be an indicator of sexual maturity (back to that oh-so-common evolutionary reason, sexual selection).

But I cannot imagine any survival-of-the-fittest logic in our keeping hairy bums.

Any ideas? — Preceding unsigned comment added by Bobbertybob (talk • contribs) 08:41, 26 April 2015 (UTC)

My layman's understanding is that things don't have to be useful to be selected for, they just have to be "not detrimental enough" to be selected against, so maybe it's the case here. And hygienic conditions were bad as they were for 99% of human history (as a species) anyway, so what's a little hair in the bum Asmrulz (talk) 09:38, 26 April 2015 (UTC)

You are assuming that evolution has stopped. Perhaps it has not. In thousands of years, we might have totally bald bottoms, or masses of fibrous keratin threads sprouting from every follicle!DrChrissy ^(talk) 09:48, 26 April 2015 (UTC)

I'd say it most surely hasn't stopped, but I don't see where in my post I assume that it has Asmrulz (talk) 10:23, 26 April 2015 (UTC)

My post was directed at the original question, not yours.DrChrissy ^(talk) 10:33, 26 April 2015 (UTC)

Then you indented incorrectly. Matt Deres (talk) 14:19, 26 April 2015 (UTC)

@Matt Deres Perhaps you would care to enlighten me as to the correct way of indenting - rather than just leaving a rather terse, negative, not-very-friendly message.DrChrissy ^(talk) 16:14, 26 April 2015 (UTC)

You indent one more tab than section you are replying to. So, if you were replying to the original post, which was not indented, you would use a single tab indent. If you don't do this, it gets very confusing, but you can always explicitly list the name of the person you are responding to. StuRat (talk) 16:42, 26 April 2015 (UTC)

There's really very little hair in the area compared to relatively recent ancestors - and remember, for many species like fruit flies that have a vastly shorter generation time and much more change at the genetic level, the actual physical changes over mere millions of years seen amount to much less, maybe a dark spot on the wing. Getting rid of hair near the anus requires an enhancer (genetics) that is exquisitely well-programmed to stop all induction of hairs in that region, while allowing hairs where they are needed. Such things take considerable design, all done in random steps, to make enough sites for transcription factors, etc. to process this logic, which starts off with quantitative differences in level and activity, into something approaching an absolute cutoff.

But also, I am not convinced the hairs there are a net negative, though I can only engage in rampant speculation. Remember for example that hairs are associated with a sebum production and distribution mechanism that might lubricate surfaces that slide against one another. They might disrupt caking of feces, though I doubt human ancestors put up with that anyway; or the sensation of feces twirling around on the hairs might have made the ancestors clean themselves... who knows? We only know evolution didn't find it to be a huge problem, i.e. there was not a very strong selection coefficient favoring changes that reduced the hairiness. Wnt (talk) 12:14, 26 April 2015 (UTC)

It may be that the hair acts as a dry lubricant, easing the friction of running/walking. Matt Deres (talk) 14:19, 26 April 2015 (UTC)

• Not all traits are adaptive traits. See also Spandrel_(biology). SemanticMantis (talk) 15:03, 26 April 2015 (UTC)

Yes, I suspect it's a pleiotropic effect, it is probably a side effect of the fact that the person has lots of body hair for some reason. That, or it's meant as a place to keep your dingleberries. It's certainly not a universal trait. μηδείς (talk) 18:16, 26 April 2015 (UTC)

(Prior to streaking in front of the police) Hyde: "I'm going to write 'I hate the fuzz ' on my ass !"

Fez: "If you hate the fuzz on your ass, why don't you just shave it off ?" - That '70s show - StuRat (talk) 21:56, 26 April 2015 (UTC)

Dying from eating too many eggs

I heard of someone that died from eating too many eggs. But the description of how they died sounded odd. They described the person dying suddenly while sitting in a chair without any signs of pain or distress and with their eyes still open at the time of death. If someone died of eating too many eggs wouldn't this have been preceded by a heart attack and the victim clutching their chest? Malamockq (talk) 16:58, 26 April 2015 (UTC)

Maybe he just happened to be eating eggs when he was stricken. I recall when Mama Cass died, it was alleged she had choked on a sandwich, but it turned out she just happened to be eating one at the time she had her fatal heart attack. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:14, 26 April 2015 (UTC)

Do you mean a diet chronically too high in eggs, possibly leading to a cholesterol overdose ? Or do you mean dying from an acute binge of too many eggs at one time ? If so, if they were eaten with salt, then that could cause high blood pressure and a stroke, if they had sodium sensitive hypertension. StuRat (talk) 17:15, 26 April 2015 (UTC)

For what it's worth, there is a memorable scene in the 1967 prison film Cool Hand Luke, where the title character played by the great Paul Newman wins a prison bet by eating 50 hard boiled eggs in an hour. Cullen³²⁸ Let's discuss it 17:28, 26 April 2015 (UTC)

Diet chronically too high is what is alleged. He was a father of 3, not some college frat boy eating tons of eggs on a dare. Malamockq (talk) 17:39, 26 April 2015 (UTC)

It still sounds more like a silent stroke (or likely a series, leading to the fatal event) than a heart attack. As you noted, a heart attack can kill quickly, but not instantly. Somebody dying of a heart attack would be expected to show signs of distress (although the symptoms are more vague in women). But a severe stroke or related event could potentially kill instantly. StuRat (talk) 17:58, 26 April 2015 (UTC)

The U.S. government is poised to withdraw longstanding warnings about cholesterol. Alansplodge (talk) 22:30, 26 April 2015 (UTC)

Yes, but what they really should do is come up with separate guidelines for LDL and HDL cholesterol, along with recommendations that foods should be explicitly labeled to show how much of each they contain. StuRat (talk) 17:36, 27 April 2015 (UTC)

Um, someone with some actual legitimate knowledge about this (i.e. not me) should probably comment, but I really doubt that it matters much how much LDL or HDL cholesterol you eat. The point of the new recommendations is that they're no longer convinced that total cholesterol in diet really has much to do with serum cholesterol, so much less would one expect (from my naive perspective anyway) that serum HDL and LDL would be separately correlated with their dietary intake.

As I understand it, and again I invite comment from some genuine expert, the reason that HDL is counted as "good cholesterol" is that, when the body wants to remove cholesterol from the arteries and recycle it into the steroid reserve in the liver, it does that by attaching it to high-density proteins. So the HDL that you see is (or has more chance to be) cholesterol moving in the right direction, whereas LDL is likely to be moving in the wrong direction. I don't see any reason to think that that's connected with the HDL or LDL in the food you eat. --Trovatore (talk) 04:44, 28 April 2015 (UTC)

Recent studies also show the recommended 1500-2300 mg salt recommendation may do more harm than good.

As for just dropping dead, this happened with my great aunt. She and my aunt were talking in the living room, my aunt went to pour a cup of tea, when she came back 30 seconds later my great aunt looked like she had fallen asleep, but shortly thereafter fell over and was declared dead on the scene. No autopsy was done, given she was in her 90's. μηδείς (talk) 01:15, 27 April 2015 (UTC)

There seem to be genetic differences in those with sodium sensitive hypertension which makes excess sodium more dangerous for them (including me). StuRat (talk) 17:39, 27 April 2015 (UTC)

Yes, I am certainly not advising people to act against medical advice. The various articles I have seen mention people with kidney and specific metabolic problems as exceptions. μηδείς (talk) 22:33, 27 April 2015 (UTC)

Also, people don't necessarily "clutch their chest" during a heart attack. Often, they just collapse. My wife's co-worker died of a heart attack at work. He was walking down the hall passed her, and just fell down in a heap mid-step. He made no obvious signs of distress until he just up and died. That someone was eating eggs, and then just died, does not mean the one caused the other. See Correlation does not imply causation and Post hoc ergo propter hoc for some understanding why people make such errors in understanding. --Jayron32 14:40, 27 April 2015 (UTC)

Does the size of the right ventricle indeed equals to the left ventricle size?

In our article ventricle is written: "The right ventricle is equal in size to that of the left ventricle, and contains roughly 85 millilitres (3 imp fl oz; 3 US fl oz) in the adult.". While in another wiki (echopedia) if i'm not mistaken it seems that the left ventricle is bigger (look at this: http://www.echopedia.org/wiki/Normal_Values) 18:20, 26 April 2015 (UTC) — Preceding unsigned comment added by 213.57.30.219 (talk)

The relative sizes can vary. Also note that the interior and exterior volumes are not always proportional. See left ventricular hypertrophy, for example. Although if both articles purport to list the normal healthy values, this may not apply. StuRat (talk) 18:42, 26 April 2015 (UTC)

But why should not they have the same volume? They have to pump the same volume of blood. Ruslik_Zero 18:43, 26 April 2015 (UTC)

The right part only has to pump the blood through the lungs which happens at low resistance and hence requires low pressure. The left part has to pump the blood to the rest of the body, and unless you live a sedentary lifestyle this requires on average more effort for the heart. So, the left part tends to be larger than the right part, especially in athletes. Count Iblis (talk) 19:29, 26 April 2015 (UTC)

In the link that mention above, we can find apparently that in normal values of heart, the left ventricle is the bigger. So the sentence on our article needs citation q source. 5.28.181.196 (talk) 19:59, 26 April 2015 (UTC)

In the following article is written that "The right and left ventricles differ greatly in their size". So till now, there's a mistake in our article. [1] 5.28.181.196 (talk) 20:05, 26 April 2015 (UTC)

Before getting to the comparison, lets be clear of about the terminology:

• Firstly, in literature ventricular volumes refers to inner volumes of the chambers, which are useful by themsleves, and required to calculate the diagnostically important parameters of ejection fraction and stroke volumes.
• Secondly, it doesn't make sense to talk of ventricular volume without indicating whether one is talking about end-diastolic (ED) or end-systolic (ES) volume. So the sentence in the wikipedia article is almost meaningless as currently written (though it perhaps refers to end-systolic volume).
• Thirdly, the original question and many of the responders are not clear about whether they are referring to the ventricular volume or the ventricular mass. The latter refers to the muscle mass of the two ventricles, and for reasons mentioned above, LV mass is significantly greater than RV mass.

Now coming to the question of volumes: The volumes of the two ventricles are indeed very much comparable, with RV volumes at both ES and ED being slightly larger; see this paper using MRI and and this paper using CT (ignore the abstract of the second paper which has some errors, and see Tables 1 and 2 instead).

Caveats: given the difficulty in measure in vivo volumes; dependence on the exact imaging modality and technique used; and large population variation, take the numbers cited in any of these papers with a pinch of salt; don't treat them as "true" measurement of ventricular volumes; and don't directly compare numbers obtained using different techniques unless you really know what you are doing and the adjustments that need to be made. Abecedare (talk) 21:06, 26 April 2015 (UTC)

Let's make it easier, if you take a heart of dead, which of the ventricles is the bigger? (I mean to the inner space) 5.28.181.196 (talk) 22:50, 26 April 2015 (UTC)

The internal ventricle volumes are roughly the same in a healthy person, having it otherwise would make no sense at all, as they are in the same circulation. What is causing the confusion is that the left ventricle is far larger on the outside, as the muscle layer surrounding is is far thicker. Fgf10 (talk) 07:15, 27 April 2015 (UTC)

N¹⁵

I have just finished this book, and in it, the author states that "Gaiduchenko suggested that...the high levels of N¹⁵ isotopes in human bone suggested that horses, very low in N¹⁵, were not eaten frequently. Foods derived from cattle and sheep, significantly higher in N¹⁵ than horses, probably composed most of the diet". My question is, why would the level of N¹⁵ be higher in cattle and sheep than in horses? Is it something to do with the fact cattle and sheep are ruminants? My googling didn't really get me anywhere.

As a side question, I found the book rather heavy on archaeology, and just a little light on PIE filling. Is there a decent, comprehensive layman's book on the Proto-Indo-European language? — Preceding unsigned comment added by BbBrock (talk • contribs) 21:44, 26 April 2015 (UTC)

Our article Isotopic signatures states "The ratio of N¹⁵/N¹⁴ tends to increase with trophic level, such that herbivores have higher nitrogen isotope values than plants, and carnivores have higher nitrogen isotope values than herbivores". This statement is uncited at the moment, but this paper has some experimental results and references to some theoretical bases for it. It would seem that this is an area where research is still ongoing. Tevildo (talk) 22:55, 26 April 2015 (UTC)

I would suspect that the difference lies in the fact that cattle and sheep are ruminants, and digest plant fiber differently compared to horses, while horses are neither ruminants, nor closely related. μηδείς (talk) 01:05, 27 April 2015 (UTC)

• Mallory's In Search of the Europeans gives a broad overview fit for a layman, although he focuses a lot on where they came from. Indo-European Language and Culture: An Introduction by Benjamin W. Fortson IV is recommended, but I haven't read it. The Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World (Oxford Linguistics)Nov 9, 2006 by J. P. Mallory and D. Q. Adams is an encylopedic source, a must have if you really want to study deeply. The American Heritage Dictionary of Indo-European Roots, Third Edition by Calvert Watkins is much more compact, and focuses mainly on PIE vocabulary found natively or by borrowing into english. It starts with a good sketch of the peoples, and weighs 1/8th of Mallory and Adams. There are many other texts. A good beginning work on linguistics in general is Anthony Burgess's A Mouthful of Air. It assumes very little prior knowledge, and maybe some grade-school familiarity with one or two languages besides English. μηδείς (talk) 03:39, 27 April 2015 (UTC)

Many thanks for the responses, and Medeis, thanks too for the suggestions. I will order the Fortson and Burgess books to start with. BbBrock (talk) 11:54, 27 April 2015 (UTC)

Should you be interested, I can give more specific recommendations based on your specific interests, BbBrock, much available online, or which I can email you at some point. Burgess is helpful because he introduces the IPA painlessly, which is the door to the rest of linguistics, once you've got a grasp on it. You should also explore all our articles on PIE, historical linguistics and the related articles that interest you. μηδείς (talk) 22:25, 27 April 2015 (UTC)

Thanks very much μηδείς, my interest is in the history of the English language. I find PIE, and its journey through to modern English, fascinating. BbBrock (talk) 20:36, 28 April 2015 (UTC)

@BbBrock: The general issue is isotope fractionation in living organisms. Δ13C is one famous example, but most organisms end up preferentially incorporating some isotopes compared to others. Δ15N is what you're asking about, but that article is unfortunately a very short stub. Isotopic_signature also has some info. SemanticMantis (talk) 03:07, 28 April 2015 (UTC)

SemanticMantis - thanks for your reply. Isotope fractionation could be just the phrase I needed. It has opened up a whole plethora of leads I can look into. BbBrock (talk) 20:40, 28 April 2015 (UTC)

surface temperature versus satellite measurements

Is this true about the big difference in surface temperature measurements and satellite readings? What is the explanation for the difference and what is the consequence? Bubba73 ^{You talkin' to me?} 23:28, 26 April 2015 (UTC)

Satellites do not measure temperature. They measure radiances in various wavelength bands, which then must be processed using various assumptions and corrections to make inferences about temperature. Thus it's not surprising that satellite "measurements" of temperature disagree depending on who is doing the processing, and that they also disagree with the surface temperature measurements. Short Brigade Harvester Boris (talk) 23:56, 26 April 2015 (UTC)

Yes, and the radiance depends on the emissivity of the surface. In other words, a barren dry landscape under a clear night sky will cool down far more than an area that has vegetation. During the day one has to take into account reflectance also. During the night, clouds cause some radiance to be reflected back down to the surface again. There are many variables to take into account. So, as knowledge of remote sensing accumulates, adjustments are made to make them more accurate.--Aspro (talk) 00:52, 27 April 2015 (UTC)

You may want to rethink that. As someone that lives in a barren, dry desert climate, the golf course grass is cooler than the desert at night. The real answer is that "it depends." Evaporative cooling can be massive or near zero depending on saturation. It's not as simple as the dry adiabatic lapse rate. I don't know if satellites pick that heat transfer up but the thermometer does. --DHeyward (talk) 14:47, 28 April 2015 (UTC)

Bear in mind we only have satellite data for say 35 years, and is a reasonably good global estimate of whatever it is they measure, although coverage of the poles has more errors than the bulk of it. We have surface temperature measurements going back perhaps 130 years to 160 years with some sort of steadily increasing accuracy, but they are subject to all sorts of sampling error in their own right, and again coverage of the poles and other places is dodgy. As such they are both /estimates/, not measurements, of global surface temperature. I believe that in the small time period where they overlap, the trend is roughly similar, a rise from 1980- 1998, followed by a plateau from 1998 to 2014. There's various bumps and valleys in that trend, but that's the gist of it. For instance here's a comparison between HADCRUT4, a thermometer based global surface temperature estimate, and RSS, a satellite based global surface temperature estimate, both averaged over 4 years.:hadcrut vs rss If we had a longer satellite record we could see whether the difference in trend between the two is just short term effects or actually significant. If it is significant then one or other or both will need to be corrected. I chose 4 years for no reason in particular, play around with it and see what difference it makes. Greglocock (talk) 00:24, 27 April 2015 (UTC)

We have an article on the author of the blog entry, Christopher Booker. I would want to see some scientific reliable sources before placing too much weight on what he says. Also the Global Warming Policy Foundation he refers to is... well, we must be civil here, so I shall hold my tongue. 88.112.50.121 (talk) 00:30, 27 April 2015 (UTC)

Hilarious to see an anonymous ad hominem attack in response to an objective question. Here's a graph that demonstrates that whatever the satellite is estimating and whatever the surface temperature people are estimating, they pretty much agree on 48 month moving average trends over the last 35 years. HADCRUT3 offset against RSS. Greglocock (talk) 00:38, 27 April 2015 (UTC)

Interesting. If replotted using a 12-month moving average RSS tends to have wider swings than HADCRUT3, i.e. here. Also the point made by 88.x is relevant: Booker is not a scientist, and GWPF is not a scientific organization (the "P" in GWPF stands for "policy"). Short Brigade Harvester Boris (talk) 01:20, 27 April 2015 (UTC)

Not many journalists are scientists, Booker's job is to write stuff in newspapers. The people leading and conducting the investigation need to be scientists and statisticians, not journalists, the people who write about it in newspapers can be journalists. Greglocock (talk) 02:26, 27 April 2015 (UTC)

I do not consider it inappropriate to point out that there are people and organizations with long established biases and agendas. Or expect them to provide evidence in support of their claims that contradict the overwhelming body of scientific evidence. There are professional conspiracy theorists out there; read the articles linked above and decide for yourself if describing these people as such is an "attack". The history of how these people have been conducting their business is a perfectly valid data point on their credibility.

For myself, I find it hilarious that you take a potshot at me on the basis of my anonymity while accusing me of an ad hominem attack. Pot/kettle, &cetera.88.112.50.121 (talk) 01:14, 27 April 2015 (UTC)

I'll spell it slowly for you, pointing out that someone is making an ad hom comment, by making an ad hom comment, is an example of irony. Perhaps I should have added a smiley emoticon to make it even more obvious. Greglocock (talk) 06:38, 27 April 2015 (UTC)

Anyway to get back to the main point of this investigation, it isn't satellite vs surface thermometers, the main investigation is into the on-going adjustments to the historical and present day surface temperature record. Greglocock (talk) 02:26, 27 April 2015 (UTC)

The OP asked specifically about "the big difference in surface temperature measurements and satellite readings." Short Brigade Harvester Boris (talk) 02:40, 27 April 2015 (UTC)

As to that I think I've demonstrated the differences are essentially tiny in a time frame of 4 years or longer, for the mere 35 years for which comparisons are available. But the referenced article is to do with corrections to the long term surface record, not satellite vs surface.Greglocock (talk) 04:02, 27 April 2015 (UTC)

Of course, we have several different reconstructions of the surface temperature record, including the unified approach of the BEST team, and they all agree quite well. I don't expect anything useful from the GWPF, although I'm surprised they got Pielke in. --Stephan Schulz (talk) 13:25, 28 April 2015 (UTC)

The OPs question has clearly been shown to be invalid, and is based on a politically motivated falsehood. Just move on. Fgf10 (talk) 07:13, 27 April 2015 (UTC)

I must have missed something, in what way is the OP's question invalid? We are talking about science here, not religion.Greglocock (talk) 11:20, 28 April 2015 (UTC)

The question is valid. Plot HADCrut3 vs. HADCrut4 and the trends are the same but there are variations. To me, HADcrut4 looks warmer and flatter than HADCrut3. The interesting thing about scientific data is always that when it gives you the answer you are looking for, it's fine. When it doesn't, the data is usually what's scrutinized first. We are in an interesting time of a "hiatus" in measured surface temperature with a rather constant increase in CO2 - this has caused both ends of GW debaters to scrutinize methods of measuring global warming and we now have two rather extreme camps of "there is no GW" and "there is no hiatus." There are all sorts of theories ranging from normal variation to volcanic activity to incorrect surface temperature measurement/integration (especially polar undercount) to trade winds to stratospheric water vapor to sunspots to stadium waves to deep ocean warming to ENSO. None of them are independent variables. There are lots of nifty correlations that are only understood as correlations. --DHeyward (talk) 14:31, 28 April 2015 (UTC)

April 27

Rollerball & Ballpoint mechanical differences--any?

From my reading of the articles for rollerball and ballpoint pens, it sounds like as far as the physical parts of the pen are concerned, there isn't a difference, and that the difference is in the quality of the ink, with ballpoint ink being thicker and rollerball ink being more watery. But am I wrong? Ignoring everything about the ink, is there a common constant mechanical/parts difference between ballpoints and rollerballs? 20.137.7.64 (talk) 17:05, 27 April 2015 (UTC)

Rollerball pen and ballpoint pen are the articles in question. It sounds like the oil-based ink in traditional ballpoint pens makes for a better lubricant, allowing a larger ball. The gel used in some rollerball pens seems to be an inadequate lubricant, resulting in skipping even with the smaller ball. StuRat (talk) 17:31, 27 April 2015 (UTC)

April 28

Parrots and chillies (probably about the 15th question on this topic)...

So, it's fairly common knowledge that (most?) parrots have a natural tolerance for the capsaicin in chilli peppers - and a parrot can eat something like a habanero, the seeds, placenta and all, without the slightest apparent distress.

What I was curious about this time though - was how high this tolerance actually goes. Would a parrot be able to eat one of the superhot chillies, with a heat in the range of the millions of Scovilles? I've heard it said that parrots are immune to capsaicin, but OTOH, some people have said that it just affects them somewhat less than humans. --Kurt Shaped Box (talk) 00:52, 28 April 2015 (UTC)

The whole question is closely related to the evolution of mutualisms between birds and plants, e.g. frugivory, zoochory, and seed dispersal. It's not just parrots - virtually all birds have virtually no aversion to capsaicin, at least compared to mammals. The idea goes like this, speaking teleologically as not-quite-correct short hand: Plant species usually "want" their seeds to be dispersed, to deal with environmental heterogeneity and uncertain growing conditions, as well as to get a better mix of mates in sexual reproduction. Mammalian digestive tracts tend to be more damaging to seeds than bird digestive tracts. So, some plant species deal with the problem by adaptation to tougher seed coats that can survive passing through a mammal. Others, like piper_(genus) Capsicum, forego the resistant seed, and instead try to make sure only birds eat their seeds, so that they will survive the easier digestive tract. This way, dispersal is more likely than without a mammal deterrent, and it is also farther ranging, giving plenty of selective pressure to plants that can make compounds that mammals avoid and birds don't mind. Of course modern artificial selection and breeding programs have made things like the ghost pepper, which probably wouldn't have evolved so hot on its own. But that's all just context and background.

As to your actual questions - I think capsaicin is mostly invisible to the bird taste receptors. Here's a few scholarly papers that relate to the topic, I might be able to find better references tomorrow [2] [3]. Here's an interesting one that discusses behavioral effects of capsaicin on birds- when injected subcutaneously... [4]. SemanticMantis (talk) 02:28, 28 April 2015 (UTC)

Ok, capsaicin binds to vanilloid receptors, specifically one called TRPV1. This paper [5] says:

"In contrast, chicken TRPV1 is insensitive to capsaicin (Jordt and Julius, 2002)"

This paper [6] says:

"Interestingly, birds have a TRPV1 ortholog even though they do not seem to taste 'hot' sensation when they eat hot peppers."

-- But now I'm out of my element. My slightly-educated-guess is that the bird TRPV1 ortholog just doesn't accept capsaicin, so it's not really a an issue of "tolerance" as we normally think of it - the birds just don't notice any burning in the first place, for the evolutionary reasons I outlined above. @Wnt: might be able to fill in some more detail on the biochem stuff. SemanticMantis (talk) 14:20, 28 April 2015 (UTC)

It looks like you have the situation well in hand, but I went to Jordt and Julius [7]. They find that the chicken vanillinoid receptor is resistant to activation by even 200x the EC50 in mammals (look at Figure 1D - clean as a whistle) But in Figure 2 they find a tiny tendency to increase activation at low pH and corresponding inhibition by the antagonist at lower pH: "perfusion of cVR1-expressing oocytes with a high dose (50 μM) of capsaicin produced a small and slowly developing enhancement of proton (pH 5.5)-evoked currents (Figure 2A). Second, pH 4.0-evoked currents were partially blocked by 20 μM capsazepine (Figure 2B), a competitive capsaicin antagonist that has also been shown to attenuate native heat-evoked responses in chick DRG neurons" This doesn't directly tell whether capsaicin could make heat seem just a little hotter, but it takes a huge amount of it to do anything at all. Now, I can't tell you for sure about the superhot chillies unless someone actually did the experiment, because it is possible, for example, that there's some capsaicin-like compound present at maybe 1% of the level of capsaicin that mammals don't notice but which is hot to parrots. In biology you never really know until you do the experiment. But a good guess would be that yes, they may well be immune. Wnt (talk) 15:34, 28 April 2015 (UTC)

Dolphin rape

So I've watched a video which claimed that Dolphins were dragging decoy humans with tracking devices into caves when they decide to drag it underwater with their penis. Could this be a predatory instinct most people call it dolphin rape but I believe it is a predatory technique — Preceding unsigned comment added by Dystopia in a bag (talk • contribs) 07:49, 28 April 2015‎

Rape is a thing that a person can do. Scientists don't usually call any animal behavior "rape". That is a human concept, and when we apply it to animals, we risk being unscientific. I mean sure, bed bugs seem to have a rough time - traumatic insemination may seem sort of like rape to us, but that's the only way they reproduce, and calling it rape is not scientifically valid. The scientific thing to do is just describe the behavior, without ascribing any motive or intent. SemanticMantis (talk) 14:24, 28 April 2015 (UTC)

See Anthropomorphism#In_science for more on what SemanticMantis is talking about. --Jayron32 17:45, 28 April 2015 (UTC)

One of the exceptions to this is that ethologists often refer to duck matings as "rape". They can be very aggressive affairs with the male (perhaps several) holding the female's head under water repeatedly. However, I agree with the above that this is a rather anthropomorphic term.DrChrissy ^(talk) 17:49, 28 April 2015 (UTC)

Well, the good ethologists don't call duck copulation "rape" ;) I've probably seen more duck mating than most of us, and indeed it can look violent and aggressive. But for all we know the ducks love it. Or they just really want to hold out for the strongest drake, or any number of other things. Nobody calls it rape when hundreds of drones chase a virgin queen bee into the sky [8], but that's probably because more most people it's harder to empathize with bugs. Here's a video of dragonflies mating, played with classical music as a beautiful affair, a "perfect dancing couple" [9]... neglecting to mention that one or both parties may die in the process, or survive with punctures to the eye, etc. [10]. My point is, sexual conflict plays out in many ways in the animal (and plant, and fungal) kingdom, and it can seem odd to us -- but when we apply value-laden human-centric terms to their behavior, we do a disservice to both them and our scientific understanding. SemanticMantis (talk) 18:20, 28 April 2015 (UTC)

Hey SemanticMantis, I am with you 100% on this. I'm not sure why this "rape" label stuck (a bit) with ducks, but it really is a misnomer.DrChrissy ^(talk) 18:33, 28 April 2015 (UTC)

All good, and you're right, it is used... So I had a look around a bit to see what kinds of serious science I could find that talks about "rape" in the animal kingdom this [11], from 1980, is the worst offender I could find. I'm fairly confident that abstract would have to be worded in a much more neutral manner to get published today. Mr. Thornhill should be trouted for referring to male Panorpa as "rapists" and considering the females "unwilling" -- how could he possibly know the volition of a scorpionfly?! Anyway, yes - "rape" can be used as a sort of casual shorthand for describing certain types of copulation, but that doesn't mean it should be. While I have no problem occasionally indulging e.g. in the teleological framing of evolution (as I did, with caveat, just above in the post about parrots), playing fast and loose with rape seems needless, tone deaf, and uncouth to me. SemanticMantis (talk) 18:36, 28 April 2015 (UTC)

Boiling

Which uses less power; 2,300 watts for 2 minutes, 1,500 watts for 15 minutes? This is not homework I'm trying to work out how to boil eggs efficiently but I'm a maths moron and can't do it myself. Thanks for your help! — Preceding unsigned comment added by 39.176.65.28 (talk) 16:02, 28 April 2015 (UTC)

Just multiply them together: 2,300 watts for 2 minutes is 4,600 watt-minutes, and 1,500 watts for 15 minutes is 22,500 watt-minutes, so the latter is a lot more energy (though only 65% of the power).--Shantavira|^{feed me} 16:17, 28 April 2015 (UTC)

I'm not sure that the OP's methods will yield a meaningful answer: bear in mind that, once raised to a certain temperature, eggs' protein continues to 'cook' even when no further heat is applied – my suspicion is that the 15 minutes will produce extremely hard boiled eggs. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 16:23, 28 April 2015 (UTC)

On the other hand, 2 minute eggs will likely be very runny. --Stephan Schulz (talk) 16:29, 28 April 2015 (UTC)

• Just to clarify a bit, Power (physics) is a measure of how much energy is consumed in a given unit of time. The unit of power is the watt, so 2300 is more power than 1500. The first scenario is more power. However, if we're asking energy, since power is energy per time, that's simple algebra to say that energy is power multiplied by time. Shantavira did that math for us all, and the second scenario consumes more energy. Just make sure to get the terms correct, it does matter so we all speak the same language. --Jayron32 17:41, 28 April 2015 (UTC)

• As far as how to boil eggs using the least energy total, that's going to depend on many factors, such as if the pot is covered or not. (A well insulated set-up would favor cooking the egg slowly, while a poorly insulated set-up would make it more efficient to cook the egg quickly (provided you had the electrical power to do so). It's also possible to cook eggs with just sunlight, or perhaps using some electricity and some sunlight (such as to preheat the water). Just starting with a room temperature egg and water, instead of cold, will make a difference. StuRat (talk) 20:04, 28 April 2015 (UTC)

Where can I find a good skeptical review of the "quantum magnetic resonance analyzer"?

A friend of mine mentioned getting a "checkup" with this device. I knew already from the name that it was pseudoscientific quackery, and a bit of web searching confirmed that it consists of a hand-held "probe" that basically just confirms that someone is holding it, and that the system prints out essentially random medical "reports" that are weighted according to the gender and age of the "patient".

There are plenty of these machines for sale on Amazon.com, and I took the time to review one of them.

What I have found so far:

• Quackwatch mentions the basic class of devices, without mentioning it by name (I've mailed Dr. Barrett to ask him to mention it specifically).
• Discover Magazine has a blog post or two that show videos of people who demonstrate that if you plug a resistor into the machine instead of the probe, it does its "gee whiz" scan and diagnoses the resistor with diabetes or kidney stones or whatever.
• The New Zealand Advertising Standards Authority found that therapeutic claims made by the product are unsubstantiated.
• The pamphlet for the machine is full of completely incoherent pseudoscience.
• I can't find any mention of it on fda.gov or cdc.gov

In summary, the machine is clearly a fraudulent device when evaluated by anyone who knows anything about medicine, biology or physics, and I want to conclusively debunk it, but before I put in the effort, I'm sure someone must have done so in the few years that it's been on the market. but I can't find a reliable source which succinctly says this. Do any of you know of one? --Slashme (talk) 18:42, 28 April 2015 (UTC)

I assume you have read the series of posts on the device in the Neuroskeptic blog since you mention that source. I doubt there is any more detailed analysis of the clearly bogus device(s). Many different devices are marketed under that generic "science-y" name and even the articles you linked above don't necessarily refer to the same device; compare [12] with [13]; and note that the device in the NZ ASA ruling doesn't have "resonance" in the name. So given that it is impossible to even nail down what any of these device (or claimed phenomenon on which they are supposedly based) is, it would be impossible IMO to find any definitive debunking. Abecedare (talk) 19:07, 28 April 2015 (UTC)

I agree that it's total bunk, but the resistor method might also "disprove" Body_fat_percentage#Bioelectrical_impedance_analysis, by calling some combo of electronic components "obese". StuRat (talk) 19:58, 28 April 2015 (UTC)