Wikipedia:Reference desk/Archives/Science/2016 November 17

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November 17

written language as part of the native competence

Is our literacy in our native language also part of the native competence?

I mean whether everything that applies to the native ability to speak a language also apply to the ability to write a language. For example do we have to learn it before a critical phase like puberty to be considered native, do non natives have some sort of "accent", and so on?

The question was more if the ability to write our native language is localized in the same region of the brain as our native ability to speak it. — Preceding unsigned comment added by 94.143.77.108 (talk) 00:02, 17 November 2016 (UTC)

Literacy is distinct from fluency. It would need to be, there are many languages throughout history which were never written. --Jayron32 02:28, 17 November 2016 (UTC)

I think the OP clearly discarded this point of view, Jayron.Hofhof (talk) 09:16, 17 November 2016 (UTC)

It think it is fairly obvious I was showing them the error in doing so... --Jayron32 12:05, 18 November 2016 (UTC)

• Spoken language requires the ability to manipulate ones vocal apparatus to produce sounds and the ability to hear and distinguish the sounds one makes as well as those produced by others. (For simplicity's sake, I'll leave out other modes of language such as sign and whistle-speech.) Many areas of the brain, and far different ones are used in this capacity than are used in reading and writing. Look at the homunculi of the motor and sensory cortices, consider the independence of the pathways leading to the eys and fingers used in reading and writing, and the mouth and ears used in speech.

It's only at deeper levels of organizaation such as concepts like "feline" or "treason" where one might expect very high correspondencein neural pathways. There is no special organ, other than the living brain in a body with the necessary faculties, that serves as a "speech" organ, and no organ dedicated to only language or only literacy. You might want to read Daniel Everrett's Language: the Cultural Tool for a thourough treatment of this from both a physiological and a "competence" viewpoint.

μηδείς (talk) 04:32, 17 November 2016 (UTC)

Activity of Bowman–Birk protease inhibitor

I was reading the page for Antinutrient when I read this line:

Protease inhibitors are substances that inhibit the actions of trypsin, pepsin and other proteases in the gut, preventing the digestion and subsequent absorption of protein. For example, Bowman-Birk trypsin inhibitor is found in soybeans.

I understand soybeans are essential in vegan and vegetarian diets as a source of protein, in tofu, soy milk, and plain soybeans, so to what degree does Bowman–Birk protease inhibitor stop absorption of protein? JoshMuirWikipedia (talk) 08:15, 17 November 2016 (UTC)

See the Nutrition section of Soybean - the soybeans have to be cooked to destroy the inhibitor. Raw soybeans are even more unappealing than the cooked variety anyway. The general concept is protein denaturation. Wnt (talk) 10:33, 17 November 2016 (UTC)

Airline hitting hobby drone

What is likely to happen if a landing airliner hits a 50-centimeter hobby drone? Anna Frodesiak (talk) 12:53, 17 November 2016 (UTC)

That could depend on where the drone hit the airplane and at what speed and angle. If you google "drone hitting airplane" you'll see plenty of discussion on it. Think about deer, for example. If you hit one head-on, you'll probably kill the deer and do a lot of damage to your car. If it's a glancing blow, you might both survive. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:56, 17 November 2016 (UTC)

Good point about googling. Sorry. :) And about scenarios, yes, direct hit by drone is what I meant. But now you've got me thinking about full speed deer and hovering drone. :( Anna Frodesiak (talk) 13:27, 17 November 2016 (UTC)

If you've seen the movie Sully and/or read about the story, a drone strike in an engine could have the same effect as a bird strike, namely that it could destroy the engine. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:46, 17 November 2016 (UTC)

"birds don’t have a big lump of lithium battery in them". -- zzuuzz ^(talk) 20:41, 17 November 2016 (UTC)

It's a sliding scale. If the drone does enough damage through being ingested into an engine, then the pilot will have a limited amount of time to redirect the aircraft with the uneven thrust and land it safely – worst case is a controlled descent into terrain. If the drone struck other parts of the aircraft, not so tragic, although it could be tricky to land at the last minute if the windshield is completely destroyed, but nowhere near as hard as if you'd lost an engine at the last moment. The Rambling Man (talk) 13:50, 17 November 2016 (UTC)

Here's quite an interesting read... The Rambling Man (talk) 13:56, 17 November 2016 (UTC)

If a drone hits a commercial airliner - even if nothing breaks and nobody gets hurt - that event still meets the definition of an "accident or incident" in the United States (as defined in 49 C.F.R. §830), or, as pilots know it, "that other NTSB thing that's on the test." Yes, this means that it entails a mandatory and immediate investigation by the Federal government. The drone pilot, who probably doesn't have the training, legal resources, or experience to navigate this Federal investigation will probably be in for a lousy time during the next several weeks, months, and years. Here are some "further reading" materials for unmanned aircraft pilots in the United States:

• The front page on FAA's website today is this news story, FAA Evaluates Drone Detection Systems Around Denver
• Here's the drone page from FAA, including a summary of the newest drone rules and a link to the mandatory drone registration system.
  • The rules are important - read all of them - but pay attention to the summary: less than 55 pounds, daylight only, five miles from any airport, no getting paid to fly, and never forget that even a small toy is still an aircraft and is subject to strictly-enforced rules and laws. Some people, who are misinformed, mistakenly believe that small toys are not aircraft, or are somehow subject to different rules than large aircraft because they are toys. If I may quote the NTSB (the federal agency responsible for investigating civil aircraft accidents, including mid-air collisions), in their 2014 regulatory order refuting the idea that toys or models are somehow distinct from regular aircraft, ""We disagree." In summary, the plain language of the statutory and regulatory definitions is clear: an “aircraft” is any device used for flight in the air."

So: pilots of small toy aircrafts, be aware! If your drone flight causes an accident, creates an emergency situation, or generally draws the ire of the aviation community around you - you will be held to the same legal standard as the pilot of any other aircraft. You will want to make sure you know, and follow, all relevant rules and regulations. Register your drone. Fly it in safe areas away from people, animals, structures, and other air traffic. Don't fly in bad weather or at night. Be responsible. Comply with other local rules, including privacy laws, nature- and wildlife- protection laws, and noise abatement ordinances. If this all seems a little heavy, or it all seems like more responsibility than you want to take upon yourself, then review the PHAK chapter on aeronautical decision-making, and decide not to fly. Nimur (talk) 16:21, 17 November 2016 (UTC)

• • So wait, the NTSB, a regulatory agency under the executive branch, can overrule a judge on a point of law? That's ... frankly appalling. --Trovatore (talk) 20:38, 17 November 2016 (UTC)

Trovatore: I concede I am not a lawyer. You raise an interesting and important question about a fundamental civics question; and on the specific point by which Code of Federal Regulations differ from statutory law, they fit into a funny nook in American system of government. I could happily write extensively about what I do know on that topic. If you'd like to continue that conversation, perhaps it belongs elsewhere, e.g. my talk page, as it's drifting far from the user's original query. Nimur (talk) 00:31, 18 November 2016 (UTC)

That's all great advice, but it's not really relevant to the question, and I think Johnny Jihad will have a different manual in hand that pretty much says the opposite on each point. :) Wnt (talk) 18:51, 17 November 2016 (UTC)

Well, the user asked "what is likely to happen if a landing airliner hits a 50-centimeter hobby drone?" ...And as I explained, in that eventuality, a lengthy, mandatory formal investigation would be very likely to happen. Nimur (talk) 19:51, 17 November 2016 (UTC)

I speculate, but imagine the question was really related to the physics of the situation, not the legality. But your input has been instructive, thanks! The Rambling Man (talk) 20:27, 17 November 2016 (UTC)

I am assuming the OP's question is about whether the engine will be damaged by the drone. My first thought was related to remembering seeing dead chickens fired by canon into a jet engine to see the effects of bird strike. The engines are designed to be able to cope with these in a limited way. I happen to be watching a programme on volcanoes which reminded me of Air travel disruption after the 2010 Eyjafjallajökull eruption. Aircraft were not allowed to fly though airspace because of fears of damage caused by dust particles! So, I would imagine that a drone being sucked into a jet engine would have highly unpredictable effects. By the way, in the UK, and I suspect this has also happened in other countries, we have had several incidents of drones being flown close to commercial aircraft even at major airports such as Gatwick and Heathrow...my favourite method of combating this is training large birds-of-prey to catch and attack them like prey. DrChrissy ^(talk) 20:35, 17 November 2016 (UTC)

I would counter that initial assumption. The OP is doubtless asking what the natural outcome of the strike might be, not simply whether the engine will be damaged. We frequently see contained engine damage from bird strike, but the point is that when an airliner is landing, there's very little time to make huge decisions and manoeuvres if an engine is struck and reduced in capacity, worse suffers an uncontained failure which may result in damage to the fuselage from remnants of the explosion. The summary is that if an engine is damaged severely, or worse, the demise of it is uncontained and it (along with some of the structure of the aircraft) destroyed, the chances of recovery of the aircraft for a "safe" landing is entirely related to the time left before landing and other remedial actions the pilot may be able to take. The Rambling Man (talk) 20:46, 17 November 2016 (UTC)

All reasonably modern twin-engined airliners can safely fly and operate for significant time on a single engine - they can not only maintain, but even gain altitude that way. See ETOPS. The Airbus 330 was the first airliner to be certified for 240 minute ETOPS, and the 777-200ER has been certified for 330 minutes. That does not hold, of course, if there is secondary damage to the wings or fuselage. --Stephan Schulz (talk) 21:34, 17 November 2016 (UTC)

Yes, that's all very well unless you're 20 seconds from landing. Which is the point I've made a couple of times. After all, a 50cm hobby drone is unlikely to affect an airliner in cruise is it?! The Rambling Man (talk) 22:20, 17 November 2016 (UTC)

Thank you all for the very thoughtful and informative replies. The big takaway for me is that if it goes into an engine near the ground it could be extremely dangerous. If it hits the windsheild, that's not good either. If it hits anywhere else, the plane has good chances of carrying on. Does that sound about right? Best, Anna Frodesiak (talk) 08:00, 18 November 2016 (UTC)

That's a fair summary, in my opinion (and in the opinion of several experts). The Rambling Man (talk) 20:14, 18 November 2016 (UTC)

Expert opinions. Now that is nice. With all the rubbish on the net, this refdesk is a golden nugget. I still think it is the best kept secret on the Internet. A rough guess is that 99% of people think that Wikipedia is articles and nothing more, no talk pages, no projects, nothing but articles. Anyhow, thanks again to all! You are wonderful!!! Anna Frodesiak (talk) 20:59, 18 November 2016 (UTC)

Is the Vo2 of the brain taken from its Q?

The Q of the brain is 13% and its Vo2 is 21% (according to Netter- histology book). My question is if the Vo2 of the brain is the percentage (21) from the Q of the brain (13%) or it is the percentage of the from the total amount of the blood? (For you to understand what I'm talking about I'll cite the book that brought me to ask it: "At rest, cardiac output is about 5 L/min in pulmonary and systemic circulations; the amount of blood flow/min (Q) and relative % O2 used/min (Vo2) are given for certain organ systems, for the resting state. At any point, most blood (64%) resides in veins and is returned to the heart’s right side. Vascular resistance is mainly a function of small muscular arteries and arterioles." (see here) 93.126.88.30 (talk) 10:13, 19 November 2016 (UTC)

Total. See the caption in this [1]. --Modocc (talk) 10:55, 19 November 2016 (UTC)

Caesium splitting frequency at zero gravity

The second is currently defined in terms of the Caesium standard. However, the latter's splitting frequency is known to vary with gravity. My question is, how much longer -or shorter- is a second at zero gravity, than the one at standard gravity, considering its current accepted definition ? — 79.113.208.94 (talk) 22:47, 17 November 2016 (UTC)

The second article, which you linked to, discusses how relativistic effects were accommodated in the definition: "In relativistic terms, the SI second is defined as the proper time on the rotating geoid." So the second is, rather anthropocentrically, defined by a standard clock located on Earth's surface. If you were in deep space, with no gravitational effects, and at rest relative to Earth, your "second" would be shorter than a SI second. --47.138.163.230 (talk) 03:23, 18 November 2016 (UTC)

Yes, precisely. My question was: by how much exactly ? — 79.113.208.94 (talk) 04:00, 18 November 2016 (UTC)

Oh, oops, I read your question wrong. Beats me! Gravitational time dilation looks like it might point you towards how to determine it, but I'm not going to be able to do it. --47.138.163.230 (talk) 04:18, 18 November 2016 (UTC)

Atomic clocks don't depend on gravity – time itself does. So if you take two perfectly accurate atomic clocks, properly synchronised, and take one of them into deep space, both will remain accurate and count exactly the same seconds, but they won't remain synchronised.

International Atomic Time (TAI) is a weighted average of over 400 atomic clocks on the Earth's surface. As they are at different elevations and lattitudes, they don't remain exactly synchronised, even when each of them is exactly accurate (which they are not) in the laboratory where it's located. The calculation of TAI compensates for this. This TAI is the basis for our terrestrial time standards. A clock in deep space won't stay in sync with TAI, but not because it measures the wrong seconds, but because time itself is different. It's important to make this distinction between locally counting exact SI seconds and creating a global time standard. The second isn't defined anthropocentrally, but TAI is. The article on second is a bit sloppy on that subject, unlike its source.

The clocks on board the GPS satellites don't stay entirely accurate in the reference frame of the satellites. They are corrected to compensate for the reduced gravitational time dilation and increased special relativistic time dilation, so they keep a constant offset from TAI. PiusImpavidus (talk) 12:22, 18 November 2016 (UTC)

"...but they won't remain synchronised." That is precisely is what the OP and IP are clearly asking about and which has been measured time and time again, because time dilation is clearly quantifiable and important since we measure their differences; irrespective of the inertial reference frame under consideration. -Modocc (talk) 15:57, 18 November 2016 (UTC)

We have an article on this (but it is badly in need of references) Geocentric Coordinate Time for just such a time keeper: "TCG ticks faster than clocks on the surface of the Earth by a factor of about 7.0 × 10−10 (about 22 milliseconds per year)." Which is 0.7 nanoseconds less than our second (proper time) or, in other words, our clocks are about 0.7 nanoseconds per second slower than TCG's proper time. This difference is tiny so I don't think twins will notice their age differences during their family reunions in anyway. :-) --Modocc (talk) 18:16, 18 November 2016 (UTC)

So if we were to add the condition of zero gravity to the current definition of the second in terms of the Caesium standard, its frequency should be changed from f = 9,192,631,770 Hz to (1 + 7·10^-10) f ≈ 9,192,631,7761⁄2 Hz ? — 79.113.234.83 (talk) 21:04, 18 November 2016 (UTC)

The frequency is invariant (unchanging) since the reference clocks differ. --Modocc (talk) 21:12, 18 November 2016 (UTC)

79, you're mixing two things up here. The definition of the second as a unit is unproblematic. You don't need to correct for gravity. The dilation happens between two different coordinate systems. --Trovatore (talk) 21:14, 18 November 2016 (UTC)

Yes. My point is: While the Cesium from one such coordinate system `blinks` X times, the Cesium from the other coordinate system `blinks` Y times, since time in one such coordinate system flows slightly differently than time in the other coordinate system. Yes ? So if earthlings living on Earth's surface have no time-measuring tools available, and they are forced to radio someone from a zero gravity world for help, they have to divide the number of `blinks` to a slightly greater value than the being which they are asking for help. Correct ? — 79.113.234.83 (talk) 21:26, 18 November 2016 (UTC)

Yes. Satellites have to be corrected because they go out of sync too. This is because time dilation also happens within each coordinate system. The twins paradox is a famous example of this since the returning twin is always younger than the stay at home twin. Also, I'm pretty sure accelerated particles decay less quickly and thus travel further in an apparatus. Likewise electrons heavy ions undergo measurable length contraction within the lab frame. There are no coordinate changes with any of these experiments. Of course, the most basic of properties such as rest mass and it's associated frequencies are invariant with reference frame so we do not have to redefine the second since all the clocks at rest [and at the same potential] with the reference clock will be ticking at the same rate. --Modocc (talk) 21:39, 18 November 2016 (UTC)

Given the fact that one second within one reference frame is different than one second within the other reference frame, they are most certainly NOT blinking at the same rate... which is clearly visible when one uses better technologies, since clocks only a few inches apart in height start displaying slightly-different values. — 79.113.234.83 (talk) 21:52, 18 November 2016 (UTC)

Sorry, but I meant when the clocks are also identical and at the same gravitational potential which is usually a local clock that has been synced. --Modocc (talk) 21:57, 18 November 2016 (UTC)

79, you have twice removed the <br> HTML tag I put at the beginning of my comment. Please do not do it again. Thanks. --Trovatore (talk) 22:02, 18 November 2016 (UTC)