Wikipedia:Reference desk/Archives/Science/2012 November 23

= November 23 =

Ammo weight
How much do the following weigh: (1) an 8-round clip for the 22-cal Hi-Standard pistol; (2) a 5-round clip for the 7.92-mm Mauser 98 rifle; (3) a 32-round clip for the 9-mm MP-40 submachine gun; (4) 5 12-gauge shotgun shells; and (5) one German stick grenade? Thanks in advance! 24.23.196.85 (talk) 00:29, 23 November 2012 (UTC)
 * 10 rounds of 9mm Luger (which is what the MP-40 would use) weigh ~120 grams. I can't help you though with magazine weight. So that's at least 0.8 lbs worth of ammunition alone, plus magazine weight. As for your others, you'd probably be better off finding some info about pack weight if that's what you're interested in, rather than individual components. Shadowjams (talk) 02:23, 23 November 2012 (UTC)
 * Well, thanks for your help, such as it is. I'm writing a World War 2 military thriller, and I want to make sure that my characters' ammo loads are not unrealistically heavy (as they are, for instance, in many computer games). 24.23.196.85 (talk) 03:34, 23 November 2012 (UTC)
 * Actually, I did some google searching for "weight of _____ cartridge" and I found a lot of forum discussions where this question is asked in various ways, and answered. Obviously differences in detail are going to matter... slugs will weigh different from shot and different from steel shot. The bullets will be more consistent, but even then certain differences may matter (steel versus brass cartridges). However, from a weight perspective, I don't think those tiny details will matter much. Just make sure you're finding the cartridge weight, and not just the bullet weight. It's quite easy to calculate bullet weight (grains is the customary measure of bullet weight, although our article is woefully deficient on talking about that usage). A grain is 64.8 milligrams. Sorry I don't have a more detailed answer, however that's a very specific list of items that I do not have. Shadowjams (talk) 05:49, 23 November 2012 (UTC)
 * Thanks! I've found the weight of the 22 LR cartridges -- 140 of them weigh only 1 pound -- and confirmed your figure of ~120 grams for 10 9-mm Parabellum cartridges, but still haven't found any info for the 7.92-mm Mauser.  24.23.196.85 (talk) 07:54, 23 November 2012 (UTC)
 * Follow-up: I've just found that 10 rounds of 7.92-mm Mauser ammo weigh about 250 grams. 24.23.196.85 (talk) 08:01, 23 November 2012 (UTC)
 * Well, I've done some figuring, and came out with a basic weapons + ammo load of about 30 pounds for most of the Maquis team, with Mike getting the heaviest load at 50 pounds (because he has to carry the Mauser), and the squad leaders (Francois, Blanche and Jacques) getting the second-heaviest at about 43-45 pounds (because they have the shotguns). These are on the heavy side, but not unreasonable.  Of course, Alfred will also get to carry most (if not all) of the demolitions, which will bring up his total load as well...  Anyway, thanks for your help, and clear skies to you! 24.23.196.85 (talk) 03:16, 24 November 2012 (UTC)

E-boats
What's the minimum number of crew needed to (A) navigate a German E-boat (not to be confused with a U-boat) from Harbor A to Harbor B without opposition; or (B) do the same while defending the boat against enemy attack? Thanks in advance! 24.23.196.85 (talk) 00:36, 23 November 2012 (UTC)


 * This account of the sinking of S-38 states that there were 23 crew members including 3 officers. It seems rather a lot. This report on the wreck of S-89 says 24 (there were different designs). The boats had reliable diesel engines, so I don't see why you would need more than 3 or 4 crew for a short journey in peacetime conditions. But that's just a guess; I may be missing something. Alansplodge (talk) 01:18, 23 November 2012 (UTC)


 * War ships are designed to be operable even when severely short-handed, in case of combat casualties. So, 3 or 4 for an unopposed journey seems about right -- and if they have to defend themselves, then probably somewhere around 7 or 8 (4 more than in the other case -- 2 per gun).  If correct, this means for me that the Maquis group can indeed get away in an E-boat, but they will have to regroup prior to boarding the boat -- the infiltration team alone (Blanche, Mike and Alfred) would not be big enough to both sail the boat and defend it against attack, so the ambush team (everyone else) will have to rejoin them, probably by charging the base perimeter. 24.23.196.85 (talk) 03:25, 23 November 2012 (UTC)


 * If the journey was longer than one day, you would need to operate a watch system so that people get a break to eat and sleep. That's why the standard crew was more than twenty - there needed to be two men for every job. Alansplodge (talk) 12:50, 23 November 2012 (UTC)


 * Thanks! So if the journey is only a few hours (as it will be in my case), then only half that number is needed to keep the boat fully combat-operational during the journey (which won't even be needed in my case -- my characters will be escaping, not raiding, so they won't need the torpedoes). 24.23.196.85 (talk) 02:37, 24 November 2012 (UTC)

TQ
hi everyone I URGENTLY need to learn how thymoquinone acts within our body: does it pass through the cell membrane? does it have a receptor? how does it change cell responses to different proteins (hormones and ligands)? thank you all

kukubah 06:35, 23 November 2012 (UTC) — Preceding unsigned comment added by Kukubah (talk • contribs)
 * Is this a homework assignment? ~Amatulić (talk) 06:48, 23 November 2012 (UTC)
 * You just asked this a few days ago and were given some answers. But Amatulic is right. There is no time I can envision when asking an "urgent" question here indicates a valid use of the reference services (neither homework nor health are allowed here, and answers here are would require verification by you before being trusted). DMacks (talk) 06:57, 23 November 2012 (UTC)
 * We could take the lead of Dilbert's secretary, who, when told something is urgent, tells him, "Good, I'll start ignoring it immediately." ←Baseball Bugs What's up, Doc? carrots→ 08:02, 23 November 2012 (UTC)


 * We could also reflect on the axiom that the urgent is rarely important, and the important is rarely urgent. --   Jack of Oz   [Talk]  01:04, 24 November 2012 (UTC)
 * One exception to that is when some object is heading your direction at high speed. ←Baseball Bugs What's up, Doc? carrots→ 17:25, 24 November 2012 (UTC)

What to do with this image
I was at Filoli a couple months ago and took this very detailed (click on it and zoom in) picture of two bees foraging on a flower. The flower was labeled "Party", so I figured I'd put the picture in the appropriate article about the plant, with the bees a useful reference to judge the size. Unfortunately, the identifier with which the Filoli caretakers chose to tag this flower doesn't seem to correspond to any article. Anybody have an idea what this is? I don't even know what category to put it in on Commons. ~Amatulić (talk) 06:48, 23 November 2012 (UTC)


 * Don't know about the flower, but another use could be in our article on bees. StuRat (talk) 06:53, 23 November 2012 (UTC)
 * I thought of that too, but the honey bee article seemed already saturated with images. ~Amatulić (talk) 08:06, 23 November 2012 (UTC)


 * There's a single-flowered dahlia cultivar named "Party" (another image) that resembles the flower in your photo. Can you remember what the foliage looked like and whether it matches that in the linked picture? Deor (talk) 12:36, 23 November 2012 (UTC)
 * Ah, that's the one, yes. Thanks. In the same patch was this other dahla picture I took. I guess that whole patch was dahlia. ~Amatulić (talk) 15:56, 23 November 2012 (UTC)

Vehicle propulsion name?
What is the formal name for this type of vehicle propulsion:

In contrast to continuous track ..? Electron9 (talk) 12:01, 23 November 2012 (UTC)


 * In contrast to continuous track they would be tires.--Shantavira|feed me 12:16, 23 November 2012 (UTC)


 * In British military parlance, it would be "wheeled" as opposed to "tracked". See Combat Vehicle Reconnaissance (Wheeled) and Combat Vehicle Reconnaissance (Tracked). Alansplodge (talk) 12:46, 23 November 2012 (UTC)
 * Also, it would be described as "8x8" ("eight by eight") because the drive from the engine is distributed to all eight wheels. According to our Mowag Piranha article, there are 6x6 and 10x10 versions as well. We have an article, Four-wheel drive, which explains the principle. Alansplodge (talk) 14:23, 23 November 2012 (UTC)

Beryllium
Why is beryllium toxic? Double sharp (talk) 12:02, 23 November 2012 (UTC)
 * I don't know anything myself, but we do have a Beryllium poisoning article that does or should be edited to include what is known. DMacks (talk) 12:07, 23 November 2012 (UTC)
 * Apparently this was asked already in 2002(!), and still does not seem to have been answered with references (it's not in any Wikipedia article that I checked). Double sharp (talk) 13:58, 23 November 2012 (UTC)
 * A 2006 review article in Clinical Immunology suggested that particular MHC class II alleles (in HLA-DP) have negatively-charged glutamic acid residues capable of complexing beryllium, resulting in the broad activation of CD4+ T cells (reminiscent of the recent report in Science explaining the mechanisms of silver "allergy").  This is plausible though the phenotype is variable and it's likely to involve more factors; for example, a 2010 report  suggests additional contribution of polymorphisms in CCR5, a chemokine receptor that has been shown to be important in T cell migration.  The HLA-DP polymorphisms may provide the trigger, and the CCR5 polymorphisms may determine severity.  -- Scray (talk) 14:42, 23 November 2012 (UTC)

Diet Related to Mental Decline
I have gone to the google search engine and have turned up studies by Olivia Okereke, but nothing in the past few years.

I am searching for the recent, original source of this important information.

"In fact, a diet high in saturated fat seemed to speed up mental decline by five to six years, compared to a diet low in this kind of fat. The study was led by Olivia Okereke, MD, an assistant professor of psychiatry and epidemiology at Harvard. It was based on data from more than 6,000 women over age 65."Pacerjp4693 (talk) 14:52, 23 November 2012 (UTC) John P. Falchi


 * I wonder if they have carefully eliminated other factors. For example, I bet the same people who sit and eat potato chips tend to do so while "rotting their brain" watching TV.  So, is it the chips, the lack of exercise, the TV, or some combo causing the mental decline ? StuRat (talk) 15:14, 23 November 2012 (UTC)
 * http://onlinelibrary.wiley.com/doi/10.1002/ana.23593/abstract Trio The Punch (talk) 16:05, 23 November 2012 (UTC)

Change in real mass or not
Suppose, a body is travelling at the speed of light, its real mass will change or it (mass) will remain same. I know the body's relativistic mass will change. I am confused between mass and relativistic mass. Sunny Singh (DAV) (talk) 15:17, 23 November 2012 (UTC)
 * First of all, strictly speaking, no physical mass can actually reach the speed of light (although it could approach that limit to any arbitrary degree, say 99.9999999%). Anyway, to answer your question, it's real (ie rest mass) remains unchanged. 66.87.126.233 (talk) 16:44, 23 November 2012 (UTC)
 * Despite the formula $$M = m/\sqrt{1 - v^2/c^2}$$ that I learnt more years ago than I care to remember, the concept of relativistic mass ($$M$$) is not used by those who work with relativity. They prefer to use just the "invariant mass" (rest mass, $$m$$).  See Mass in special relativity for the momentum vectors preferred by mathematical physicists. The following quote from Taylor & Wheeler's Spacetime Physics reflects current thinking:
 * "The concept of "relativistic mass" is subject to misunderstanding. That's why we don't use it. First, it applies the name mass - belonging to the magnitude of a 4-vector - to a very different concept, the time component of a 4-vector. Second, it makes increase of energy of an object with velocity or momentum appear to be connected with some change in internal structure of the object. In reality, the increase of energy with velocity originates not in the object but in the geometric properties of spacetime itself."
 *  D b f i r s   17:42, 23 November 2012 (UTC)

I want to know as the body's velocity will increase (reaching the speed of light, but not more than that), more matter will be added to its mass or its mass will always remain constant even if it travels at the velocity of 200,000km/s. Sunny Singh (DAV) (talk) 19:07, 24 November 2012 (UTC)
 * "Matter" and "mass" are easy to confuse, but they are distinct concepts, since mass is a property of matter. Matter is not added to the body, but when a body reaches very high velocities, its mass increases. This is because you need a greater force to accelerate it by the same velocity difference than you would need if its speed was lower. As noted above, "relativistic mass" is a confusing term, but, yes, it is valid to speak of relativistic mass, which (defined as the proportionality constant between force and acceleration) is given by:


 * $$m= \frac{m_0}{({1 - \frac{v^2}{c^2})}^{3/2}}$$

where $$m_0$$ is the rest mass (which, by definition, is a constant). You can see by the equation how mass tends to infinity as the velocity approaches the speed of light, meaning that it is impossible to accelerate objects so that they surpass c. Hope this clears things up. -Anagogist (talk) 23:47, 24 November 2012 (UTC)


 * Yes, the amount of matter remains constant (unless it is losing mass to accelerate), and the mass as measured by an observer on the moving body will not change from its invariant mass (rest mass) whatever the speed, but the apparent mass as observed by a "stationary" observer will seem to increase according to that formula (without the sesquipedal power?) The apparent increase can be thought of as an illusion caused by the distortion of space-time, especially when you remember that an observer on the "moving body" will observe a relativistic increase in the apparent mass of the observer "at rest" on the Earth (and of the Earth itself).    D b f i r s   16:00, 25 November 2012 (UTC)

Diamond plate armor
Suppose there existed a full suit of plate armor made entirely out diamond rather than the usual iron or steel. Someone told me that this diamond plate armor would be useless in combat because it would be easily shattered. Is he correct? Diamond has higher hardness than iron or steel, so shouldn't this suit of diamond armor be less shatterable than ordinary plate armor? —SeekingAnswers (reply) 22:04, 23 November 2012 (UTC)


 * It's a common misconception that hardness and toughness are the same thing. They are not. See this video for a good real-world demonstration. AFAIK, a diamond plate would shatter in a similar way if you gave it a good whack with a sledgehammer. Not really sure how it would hold up against something like a sword - certainly it would be v. difficult, if not impossible to slice though the plate. --Kurt Shaped Box (talk) 22:24, 23 November 2012 (UTC)


 * Perhaps if a support structure were used such that even cracked diamond would stay in place any projectiles would be so dispersed that they pose very little danger? Electron9 (talk) 00:08, 24 November 2012 (UTC)


 * I've seen a funny seen in a movie, where a character tries to disprove an assertion that a particular gem is a diamond. He erroneously reasoned that since he was able to crush the diamond into pieces with a simple hammer, it must have been a fake, only to be embarassed by his naivity. Plasmic Physics (talk) 22:36, 24 November 2012 (UTC)


 * What kind of combat are we talking about here? European swords were heavier and less sharp which was for crushing armour. Asian swords were lighter and sharper for slicing. Then there are of course maces, arrows, pikes, cannon fire and a whole host of other things that you might find on battlefield in the middle ages. Then maybe you're actually talking about a modern battlefield with .50 calibre bullets, IEDs and laser guided bombs. Or maybe a battlefield with aliens from outer space with immensely powerful firearms, immortals who bring each other back to life by calling out their names, epic duels on flying skateboards, and a blatant disregard for anything logical or previously established. As noted above diamond is more resistant to cutting than say steel, whereas most weapons impact the armour and create a shock which is most easily survived with an optimum balance of ductility and strength. Diamond has essentially no ductility. 203.27.72.5 (talk) 07:06, 25 November 2012 (UTC)

What peak pressure from a explosion in joule and required ground depth?
What peak pressure will a ground surface be exposed to from an above ground explosion measured using the equivalent energy in joule and specifically how deep would an underground bunker have to be depending on soil or rock inertia and shear strength of said material etc? I assume that the explosion energy is the decisive factor not the type of explosion process. I didn't find any practical information in the relevant wp articles, specifically on the the occurring pressure. Electron9 (talk) 22:21, 23 November 2012 (UTC)

Gunshot
Is firing a 410 or 20 gauge shotgun 1 or 2 times a month while hunting, without hearing protection,  enough to cause hearing damage? Apparently most hunters don't use hearing protection so they can hear the animals walking. --Wrk678 (talk) 22:30, 23 November 2012 (UTC)
 * Sorry, but questions about the functions of and effects on your inner ear do amount to a request for medical advice that should be related to a doctor. μηδείς (talk) 22:54, 23 November 2012 (UTC)


 * It most certainly does not, unless we have evidence that the OP is a hunter who uses a 410 or 20 gauge shotgun 1 or 2 times a month while hunting without hearing protection. Medical questions are perfectly acceptable unless they request a diagnosis, prognosis, or other personal advice.  --140.180.246.185 (talk) 00:48, 24 November 2012 (UTC)
 * It's a borderline case. To answer it factually, you would have to determine the loudness and duration of the sound, and compare that to some table or another that indicates what levels and/or durations of noise are likely to cause hearing impairment. The OP could do that. OR, he could ask his doctor, who should either know the answer or know someone who would know the answer. ←Baseball Bugs What's up, Doc? carrots→ 01:26, 24 November 2012 (UTC)
 * So, while bullshit opinions will simply amount to opinion, only actual answers to this question would amount to medical advice? Get on with it then, where are the refs? μηδείς (talk) 02:28, 24 November 2012 (UTC)
 * I'm trying to subtly suggest to the OP that he do his own research. It's possible that info is even in wikipedia. ←Baseball Bugs What's up, Doc? carrots→ 04:59, 24 November 2012 (UTC)

As the OP didn't indicate they thought they were suffering from hearing loss or they were planning to do any shooting I fail to see how it can be a request for medical advice. Here is a list of how loud various shotguns are and if they would cause hearing loss. CambridgeBayWeather (talk) 15:29, 24 November 2012 (UTC) This list isn't as comprehensive as the one CBW found, but makes clear that virtually all guns are loud enough to cause hearing loss. Matt Deres (talk) 19:35, 24 November 2012 (UTC)
 * Yes most hunters don't wear ear protection (in the old days many wouldn't even wear it at the range) and yes it causes hearing loss. Gunshots are exceptionally loud; the only reason they don't cause more damage is because their peak sound is so short. To what extent is difficult to determine. Our article on Earmuffs has some numbers about sound level and duration. There are modern earplugs that compress at a high pressure wave, which provide normal levels of hearing but protect somewhat against loud sounds. Some militaries provide these, and some hunters use them. They aren't basic foam, they look more like concentric cones of plastic. Shadowjams (talk) 03:50, 25 November 2012 (UTC)