Wikipedia:Reference desk/Archives/Science/2013 August 14

= August 14 =

Ship traffic controller
Is there some kind of ship or sea traffic controller for straights and such? Or how do they know that ships won't crash? OsmanRF34 (talk) 00:56, 14 August 2013 (UTC)


 * If by controllers you mean the equivalent of air traffic controllers then no, they do not exist in international waters. However, in some busy lanes there are Traffic Separation Schemes where conventions are set by the International Maritime Organization that all ships are expected to follow.  An example is the Dover Traffic Separation System which covers the busiest shipping route in the world, the English Channel.  Spinning  Spark  01:20, 14 August 2013 (UTC)
 * Air traffic controllers operate mostly only around airports right? Not general "international air space". Similarly, I thought shipping ports had controllers. There is a big tower at the port near where I work that even looks like an air traffic control tower. The only reference I could find after a very quick search is this [about the control at Sydney harbor. [[User:Vespine|Vespine]] (talk) 01:28, 14 August 2013 (UTC)
 * Ports tend not to be in international waters. That is a very different situation.  Shipping will be controlled by the port authority and ships will often be required to take a local pilot on board while entering and exiting.  Your statement about air traffic controller is also incorrect.  Regions outside airports can also be controlled airspace - airways for instance.  In England there is almost nowhere that is not controlled airspace by someone. See also North Atlantic Tracks as an example of controlled airspace in international airspace over the Atlantic.   Spinning  Spark  01:52, 14 August 2013 (UTC)
 * The most accurate way to say it then would then be, in some places yes, but in most places no. Mingmingla (talk) 03:59, 14 August 2013 (UTC)


 * Not all air traffic controllers work at an airport, see Area Control Center. Some of those controllers may be responsible for international air space. CambridgeBayWeather (talk) 05:54, 14 August 2013 (UTC)
 * Straits as well as ports may require pilots. See to hire a pilot for the Detroit River (err, strait) Rmhermen (talk) 12:51, 14 August 2013 (UTC)


 * Harbor master μηδείς (talk) 23:56, 14 August 2013 (UTC)


 * There's something like this for monitoring shipping in the international Strait of Juan de Fuca and other nearby waterways—major shipping routes to nearby ports in Seattle, Vancouver, and others. Overview here. Vessel traffic centers monitor the larger ships, which are required to report by voice. Traffic control apparently gives direct navigational orders about 30 times a year to prevent collisions. It's basically a Traffic Separation Scheme, but with "extra stuff" for dealing with ships leaving the Strait of Juan de Fuca via a number of other straits, some in Canada and some in the US. The charts for the eastern end of the Strait of Juan de Fuca are rather complex. Pfly (talk) 03:10, 17 August 2013 (UTC)

How is this slide possible?
Can anyone enlight me how come the car in this doesn't flip over? It's sliding some fair distance, velocity perpendicular to the wheels direction. How is that possible? Zarnivop (talk) 13:11, 14 August 2013 (UTC)
 * C'mon, it's 9GAG, it's probably manipulated or something. ☯ Bonkers The Clown  \(^_^)/  Nonsensical Babble  ☯ 13:14, 14 August 2013 (UTC)
 * Loose dirt. Low center of gravity. Professional driver. --Onorem (talk) 13:19, 14 August 2013 (UTC)
 * Drifting (motorsport) - In the interest of actually also providing a ref. --Onorem (talk) 13:24, 14 August 2013 (UTC)
 * The video looks speeded up to me. Otherwise, it looks like fairly typical rally driving on a low-grip surface. AndyTheGrump (talk) 13:20, 14 August 2013 (UTC)
 * See also Scandinavian flick. AndyTheGrump (talk) 13:28, 14 August 2013 (UTC)
 * Excellent, Top-Gear DID flip-over. So it's a pro-biz: modified car, pro driver, weight shifting galore. Thank you. Zarnivop (talk) 16:51, 14 August 2013 (UTC)
 * If you read it carefully, Top Gear (note the lack of hyphen) flipped over a van while trying to do a flick. Slight difference between a commercial van and a rally car..... Also, no pro driver required, again if you read the Scandinavian Flick article you'll see this is regularly taught in driving classes in Scandinavia 82.0.112.151 (talk) 22:02, 14 August 2013 (UTC)


 * Stunt driver, possibly attempted many times until they got it just right. Kind of like that one scene in The Blues Brothers where they go into a 180 spin and come to a stop perfectly in a parallel-parking spot next to a restaurant. ←Baseball Bugs What's up, Doc? carrots→ 05:11, 15 August 2013 (UTC)


 * I wonder if the wheels and other turning parts inside cause a gyroscopic effect that contribute resistance to flipping. Richard-of-Earth (talk) 08:28, 15 August 2013 (UTC)


 * The gyroscopic effect is not very important for racing cars, but plays a major role for racing motorcycles. Dauto (talk) 15:09, 15 August 2013 (UTC)

Fatty acids and the brain
Why does it say in Fatty acid, "Despite long-standing assertions to the contrary, the brain can use fatty acids as a source of fuel", but in starvation response, it says, "Fatty acids can be used directly as an energy source by most tissues in the body, except the brain, since they are unable to cross the blood–brain barrier." ScienceApe (talk) 16:43, 14 August 2013 (UTC)


 * It looks like you've uncovered an inconsistency, and a way to make WP better. Thanks! The first sentence has two cited sources, here, and here . The first one specifically says "Glucose is the dominant oxidative fuel for brain, but studies have indicated that fatty acids are used by brain as well." The second one is titled, in part "Heptanoate as a neural fuel:" These are from reputable journals, 2003, 2012, respectively, and they both seem to say that the brain can use fatty acids, despite what we used to think. So I'd say that the starvation response article should be modified to say simply "Fatty acids can be used directly as an energy source by most tissues in the body." But I'm not feeling very bold at the moment, and this is far from my expertise. SemanticMantis (talk) 20:36, 14 August 2013 (UTC)
 * After thinking a bit and reading more of the sources, I felt bolder and removed the claim that fatty acids cannot be used by the brain from starvation response. If someone thinks I got it wrong, they can revert. SemanticMantis (talk) 22:56, 14 August 2013 (UTC)
 * Emergency medical technician training I received indicated that due to the brain's inability to process any blood-borne energy source except glucose, low glucose levels in the blood will be fatal unless corrected promptly. However, this information was given in a lecture and I don't have a published source for it.
 * It is conceivable that the brain might be able to make some use of energy sources other than glucose, but not at at a high enough level to sustain life in the absence of glucose. You might reexamine your references with that possibility in mind. Jc3s5h (talk) 23:15, 14 August 2013 (UTC)
 * Well, the story I'm seeing is basically that a long-held belief has been overturned by more recent evidence. That scientists and textbooks used to say: "fatty acids cannot cross the blood-brain barrier, and cannot be metabolized by brain tissue". More recently, research has shown that at least some fatty acids can be metabolized in some circumstances. That doesn't at all contradict what you report from EMT training. Indeed, the sources above make it seem like fatty acids contribute a very small part to the overall brain metabolism budget. My point is, if there is even one exception to this "rule", then there's no need for an article to go out of its way to mention it. What is probably called for is that the starvation response article have a short paragraph about how extended low blood glucose is bad for the brain, because glucose is the primary source of energy, etc. But I can't write that. What I can do is delete an unnecessary reference to a likely outdated/wrong "rule". Again, I'm no expert, and I have no horse in this race. It is a great question here though, because it will (hopefully) get more expert users and references to help clarify the issue :) SemanticMantis (talk) 23:42, 14 August 2013 (UTC)
 * The brain also can metabolize alcohol: "Some alcohol metabolism also occurs in other tissues, including the pancreas (3) and the brain, causing damage to cells and tissues (1)." from National Institutes of Health (USA). Edison (talk) 01:23, 15 August 2013 (UTC)