Wikipedia:Reference desk/Archives/Science/2017 July 7

= July 7 =

Meaning of "angles of the jaw" (and a source if possible)
Hey all. I am currently working on an article under featured review: Glossary of bird terms. A poster at this section of the featured review has asked about the article's definition for a birds, which I defined in the article by quoting a source, as:
 * The posterior part of the underside of a bird's head, described as "a continuation of the chin to an imaginary line drawn between the angles of the jaw".[footnote]

If you read the discussion, I have crapped out on finding a source for what "angles of the jaw" means. I have postulated what I think it means but I'm not sure I'm correct. All the source I've found (not necessarily bird related) use it without defining it. Can anyone dig up a source, maybe from JAMA or something, that defines the expression? Anyone sure of the meaning? Thanks in advance--Fuhghettaboutit (talk) 01:10, 7 July 2017 (UTC)


 * Is it possibly a place corresponding to the Angle of the mandible...? --CiaPan (talk) 10:07, 7 July 2017 (UTC)
 * Oh, I forgot to ping. Here it is: . --CiaPan (talk) 10:08, 7 July 2017 (UTC)
 * There is also something called a gonydeal angle mentioned in Beak section. However, my knowledge in ornithology and general anatomy, and even English language, is not sufficient to let me guess if it has anything to do with angles you seek. --CiaPan (talk) 10:17, 7 July 2017 (UTC)
 * Aha, angles of the mandible! Well done CiaPan. I will link that to the term. Glad to see my guess as to what it is was on target.--Fuhghettaboutit (talk) 11:48, 7 July 2017 (UTC)

Exercise
Please list some exercising movements for warm-up, stretching and building the whole body (bit by bit and or as well as in whole) without using any exercising tools. Name with Illustrations of the move(ment)s desired. 103.67.156.122 (talk) 14:45, 7 July 2017 (UTC)


 * See Calisthenics. Loraof (talk) 16:40, 7 July 2017 (UTC)
 * See also Dynamic Tension --TrogWoolley (talk) 16:53, 7 July 2017 (UTC)


 * Starting to do the exercise (e.g. running) itself is good enough. The idea that you need to do a warm-up before exercising has been debunked by rigorous scientific studies. There is no relation between injuries and doing a warm-up, not even for sports where you burden your muscles heavily like body building. While authoritative sources claim otherwise and continue to say that warm-up is recommended to prevent injuries, these statements are not based on scientific evidence in the form of statistically significant more injuries when people don't do the recommended warm-up exercises. Note that Jack LaLanne never did warm-ups, he once said ""15 minutes to warm up? Does a lion warm up when he's hungry? 'Uh oh, here comes an antelope. Better warm up.' No! He just goes out there and eats the sucker."" Count Iblis (talk) 20:38, 7 July 2017 (UTC)


 * From our article Warming up—mixed results, with citations:
 * ''The risks and benefits of combining stretching with warming up are dispute, although it is generally believed that warming up prepares the athlete both mentally and physically. In a meta-study of 32 high quality studies, about 4/5 ths of the studies showed improvements in performance.[1] Warm-up programs can improve the strength of the knee muscle, which, in turn, may decrease injuries.[2] A comprehensive warm-up program did not significantly decrease injuries in football compared to a control group.[3] -Loraof (talk) 21:02, 7 July 2017 (UTC)
 * It's stretching–especially static stretching–before exercise that has been found to be worse than useless. Warming up (without overstretching) is just a sort of exercise, n'est–ce pas? Abductive  (reasoning) 03:38, 8 July 2017 (UTC)
 * One of the most practiced worldwide (250 million ) and thus most successful seems to be chinese Tai chi. --Kharon (talk) 07:27, 8 July 2017 (UTC)

Modern torpedoes aren't design to hit a ship?
I read somewhere that, "many modern torpedoes aren't designed to strike a ship, but instead explode directly underneath it. The shockwave in the water will move so much water away from the ship that it will literally bend and break under its own weight." Is this true? ScienceApe (talk) 17:41, 7 July 2017 (UTC)
 * Where did you read it? ←Baseball Bugs What's up, Doc? carrots→ 17:48, 7 July 2017 (UTC)


 * Choosing a random article for a modern torpedo, Spearfish torpedo, I find the phrase "A standoff detonation under the keel enhances blast effects against surface ships through the amplification of stress resulting from the interaction of the explosion's products and the flexible structure of the ship.". Unfortunately, it's not referenced, except to an impressive youtube video of a test firing. ApLundell (talk) 18:06, 7 July 2017 (UTC)


 * There are many references:    ... It shouldn't take long to find one that is considered "reliable." 209.149.113.5 (talk) 19:43, 7 July 2017 (UTC)


 * We have an article proximity fuse. Sagittarian Milky Way (talk) 21:17, 7 July 2017 (UTC)


 * It has been a goal since before WWII. It was mostly needed during WWII, because the prime target of the day, a capital ship, would typically have a torpedo bulge. This is a form of spaced armour around the waterline. The easiest way to defeat it was thought to be by exploding beneath the ship.
 * The difficulty was in how to control the depth of the torpedo, and how to fuze it to explode beneath. US submarine-launched torpedoes at the start of WWII were particularly bad for this. The Mark 14 torpedo couldn't reliably control its depth, its Mark 6 exploder had problems both with magnetic detection when running beneath the ship, or its contact pistol when it had a direct impact. Andy Dingley (talk) 21:25, 7 July 2017 (UTC)


 * As for a reference try: Torpedo: The Complete History of the World's Most Revolutionary Naval Weapon (p. 157) by Roger Branfill-Cook, in a section headed "Explosions beneath the keel". This explains the physics behind it, but also says that it will be less effective against ships larger than a modern frigate or WWII destroyer. Contact torpedoes were used by the commander of HMS Conqueror (S48) in his successful attack on the large cruiser ARA General Belgrano in 1982; however the usual line is that the more modern Tigerfish homing torpedoes that he also had available were of doubtful reliability. Alansplodge (talk) 22:25, 7 July 2017 (UTC)
 * The history of the Fishfart and Stingwhelk torpedoes, and their unreliability, is left as an exercise for the reader in 1980s UK defence procurement. Andy Dingley (talk) 23:10, 7 July 2017 (UTC)
 * For Andy's second humorous reference, see Stingray torpedo which had to be totally redesigned just as development was nearly complete. Unlike the Tigerfish, it was made to work in the end. Alansplodge (talk) 08:40, 8 July 2017 (UTC)
 * Steve Bell's If... Andy Dingley (talk) 09:22, 8 July 2017 (UTC)

I have added the Branfill-Cook ref to the Spearfish article and using the same ref, have added two paragraphs to Torpedo. Alansplodge (talk) 17:48, 8 July 2017 (UTC)

Dog regurgitating tater tots
In this short nature documentary a dog is seen to regurgitate small food morsels in a form which appears they did not enter the stomach. Most don't seem to have lost their integrity and they appear largely dry. Could these have been anywhere between the mouth and the stomach? Could the dog have been expecting to be called out and was prepared to have to regurgitate? — Preceding unsigned comment added by 145.255.245.88 (talk) 18:04, 7 July 2017 (UTC)
 * They were obviously in the mouth. Ruslik_ Zero 20:45, 7 July 2017 (UTC)
 * So you reckon the dog retained them in its mouth to determine whether their loss would be noticed before eating? I can't think of any other explanation. Maybe one has to think like a dog. --145.255.245.88 (talk) 00:09, 8 July 2017 (UTC)
 * It could well be that it's a trick. Not that I think it's impossible for a dog to do this on its own initiative; they very often carry things around in their mouths before ultimately deciding to eat them.  Still, something feels a bit artificial about the video.  In any event, it's certain that dog did not regurgitate those items.  Dogs strain quite noticeably (and audibly) during the act of regurgitation (and even more so for vomiting).  Plus, as you pointed out in your initial comments, the integrity of those tots would not have been as it was, had the dog ingested the tots--but that's true even if the tots had been consumed even a little, aside from being held in the oral cavity momentarily.  This doggy got a taste, but very little satisfaction--unless the motive had more to do with attention than appetite!  S n o w  let's rap 01:34, 8 July 2017 (UTC)


 * In thinking like a dog, remember to take account of their physical differences. Dogs don't have hands (though I suspect cats are secretly working on it) so naturally use their mouths to carry things they don't necessarily intend to eat, at least not immediately. {The poster formerly known as 87.81.230.195} 90.211.129.9 (talk) 08:17, 8 July 2017 (UTC)