Wikipedia:Reference desk/Archives/Science/2015 August 17

= August 17 =

Storks and hail
How do storks protect their nests from hail?--62.72.109.90 (talk) 09:08, 17 August 2015 (UTC)


 * I've done some looking around and I can't actually find any evidence of any birds protecting their nests from hail. Eggs are pretty strong, I don't know if the small hail you normally get would damage the eggs anyway, and big hail doesn't happen enough for it to be something they need to do, maybe. Sorry for the lack of references, but I couldn't find any either way 81.138.15.171 (talk) 11:12, 17 August 2015 (UTC)


 * Birds often have to repairs nests, and hail damage would be another reason to do so. As for the eggs, they could protect them with their bodies, or if the hail was large enough to hurt the adults, they could abandon the nest for someplace safe (say sheltered under a tree) and try laying eggs again at the next breeding season. StuRat (talk) 14:30, 17 August 2015 (UTC)
 * If you mean specifically "nests" rather than "the eggs in the nest". this site has some interesting information about stork nests, such as some stork nests are known to have have been used for hundreds of years, and that each stork pair that uses a nest will add and repair the nest each season. If you did mean eggs, I guess the eggs incubate for about a month during spring, which is not the most hail prone month, perhaps surprisingly in some parts of Europe summer is the month with the most hail storms. Vespine (talk) 01:20, 18 August 2015 (UTC)

Why do human physical, emotional, mental peaks vary so much by study?
Generally they just say it's between 25 and 35 years of age but that's a very wide margin. Same with physical maturity, this differs alot too and also does not coincide with peaks. Why? 94.14.230.255 (talk) 10:15, 17 August 2015 (UTC)


 * It's feature, not a bug: Human_variability. SemanticMantis (talk) 13:52, 17 August 2015 (UTC)


 * Also, the peaks are rather sinusoidal, meaning there's lots of change at the beginning and end of the curve, but very little in the middle, making it difficult to find the exact peak. And the peak may also vary by diet, exercise, etc., too. StuRat (talk) 14:35, 17 August 2015 (UTC)

sunlight
Is sunlight bounced off a mirror the same as sunlight received directly? does it still contain vitamin d and grown plants? — Preceding unsigned comment added by 62.37.237.15 (talk) 11:32, 17 August 2015 (UTC)


 * The light doesn't "contain" vitamin D, of course. It's human skin that produces the vitamin when light shines on it.  Mirrors do reduce the light slightly in that the reflected light is not quite as strong as the incident light, but usually the frequencies required for vitamin production and photosynthesis will still be present, just in reduced quantities, especially at the UV end which is important for vitamin D. In most mirrors, the light has to pass twice through the glass, so there is double the absorption of UV light, and some types of glass absorb nearly all the UV.  Metal mirrors might be more effective for reflecting UV light?    D b f i r s   11:57, 17 August 2015 (UTC)


 * The material used in the mirror is also important, see reflectance. I think the most common metals used in mirrors are aluminium and silver. Silver is a bit better at reflecting visible light, and therefore better for photosynthesis, but silver is quite a poor reflector in the UV part of the spectrum, especially compared to aluminium, which reflects over 90% of near infrared ultraviolet radiation. - Lindert (talk) 12:11, 17 August 2015 (UTC)


 * Did you mean to switch from discussing UV to IR, or was that a mistake ? StuRat (talk) 14:33, 17 August 2015 (UTC)
 * That was a mistake, thanks. - Lindert (talk) 14:40, 17 August 2015 (UTC)


 * Fused quartz oder similar transparent for UV light ist required. The mirror also needs to reflect, not to absorb the VU light. If the mirror is bend, it focusses more light to the same part of the skin. -- Hans Haase (有问题吗) 19:32, 17 August 2015 (UTC)

mechanism of beryllium toxicity
Beryllium is toxic. So what is the exact mechanism for its biological activity? The beryllium article says it replaces Mg in some enzymes, but is frustratingly non-specific about going into further details. and the beryllium poisoning article talks a lot about the effects but not much on the causes. Double sharp (talk) 15:41, 17 August 2015 (UTC)
 * The first result here looks promising. -- Jayron 32 16:12, 17 August 2015 (UTC)
 * The introduction of this is a bit more specific, as the link above really just describes symptoms, not mechanisms. You'll find that most sources are frustratingly non-specific because the exact mechanisms are still unknown, as far as I'm aware. Fgf10 (talk) 18:35, 17 August 2015 (UTC)
 * Wow, the copyediting in that piece is bad. First sentence of the conclusion:  "Beryllium has some useful but undoubtedly harmful effects on health and well-being." --Trovatore (talk) 18:44, 17 August 2015 (UTC)
 * You know there's more links there. Like, if the first one doesn't serve your purposes, keep going.  If answering the question is important, it's undoubtedly important enough to look at more than just one potential source... -- Jayron 32 19:12, 17 August 2015 (UTC)
 * Hey, I didn't ask the question. I'm just sitting on the sidelines, and I happened to notice some bad writing that I could make fun of. --Trovatore (talk) 19:17, 17 August 2015 (UTC)
 * So the exact mechanisms are still unknown? Wow, that is a frustrating state of affairs, especially if you're interested in improving the beryllium article! So it seems that (from the article Fgf10 linked to) beryllium mostly goes into the lungs, where it is perhaps a carcinogen(?). Additionally it is not that reactive, which is generally not good for something that mostly goes into the lungs, so sensitivity can develop (per Nil Einne). Double sharp (talk) 13:55, 20 August 2015 (UTC)
 * Interference with enzymes sounds like a plausible mode of action. Beryllium is in the same group as magnesium, so they have the same ionic charge. Magnesium is an essential cofactor for many enzymes, so disruption of those enzymes would be harmful. Lead poisoning seems to work similarly, with lead ions displacing ions of other metals in enzymatic reactions. The other mode of action for metal poisoning seems to be free ions of the metal generating free radicals, which then cause cell damage. This happens in iron overload, for instance. --108.38.204.15 (talk) 19:32, 17 August 2015 (UTC)
 * Are you sure about the first? My reading of the above suggests it appears to be more of a combination of an immune respose, plus something that's fairly inert and so is problematic when it gets into places like the lungs (somewhat similar to Asbestosis), particularly since sensitivity can develop in some cases. Perhaps the first one is of relevance to the carcinogenic effect. And the second one could be a general factor. Nil Einne (talk) 20:17, 17 August 2015 (UTC)
 * I'm slightly skeptical about free ions of Be, as Be2+ would have a really high charge density and would polarize nearby electron clouds very strongly (which is why Be forms mostly covalent compounds). But BeII replacing MgII does seem quite plausible, particularly since BeII apparently coordinates better than MgII (Greenwood & Earnshaw 2nd edition, p.107). Double sharp (talk) 13:40, 20 August 2015 (UTC)
 * My feeling is that this should have something to do with the properties of beryllium oxide. My impression is that when strange stuff is found inside the body that won't yield to lesser means, the body wraps it up in macrophages to form a granuloma, then tries to oxidize the hell out of it with hydrogen peroxide, bleach, and other reactive oxygen species.  In some cases, especially oxides (silicosis, siderosis) this treatment simply is never going to have an effect on the foreign particles. Wnt (talk) 23:53, 17 August 2015 (UTC)
 * Well, according to its MSDS BeO is a known carcinogen, and is very inert. Additionally, oxidizing Be to BeO releases an incredible amount of energy according to Energy density – half that of combusting the same mass of hydrogen! This doesn't seem like a good combination. Double sharp (talk) 14:07, 20 August 2015 (UTC)

Most of the papers I see in pubmed on this seem to suspect an immunological basis for this disease. This paper and others present evidence that beryllium triggers an immune response by interacting with the major histocompatibility complex. There are also plenty of papers discussing the interaction of beryllium ions with various non-immune-related proteins in mouse models or cell culture, but it's not clear that such findings have any relevance to human health. Maybe if I or someone else finds a good review on the topic, the content will get added to the article. Someguy1221 (talk) 05:55, 18 August 2015 (UTC)