Wikipedia:Reference desk/Archives/Science/2016 July 4

= July 4 =

New Madrid earthquake damage zone


What geological factors (aside from the horizontal extent and severity of a fault, of course) influence the amount of surface (mi2, km2) that is affected by an earthquake with its epicenter at a given location? In this case, I'm wondering why a 6.8 earthquake at New Madrid would cause heavy damage as far east as eastern Ohio while causing lesser damage in much of southeastern Missouri — not to mention the far tinier area damaged by a Los Angeles earthquake of slightly lesser strength. Nyttend (talk) 04:40, 4 July 2016 (UTC)


 * Well for one, I believe this is a map of structural damage. The New Madrid earthquake took place when there were no seismic codes, while the Northridge quake took place in an area with very good seismic codes. Besides that, soil type and terrain will play a role. Different types of ground transmit seismic waves differently. The Los Angeles area is basically a bunch of mountain valleys bunched up against the sea, so the mountain terrain will attenuate seismic waves. And the depth of the hypocenter will influence how far the waves travel. --71.110.8.102 (talk) 06:12, 4 July 2016 (UTC)


 * To back that up with an anecdotal note, I lived through the Northridge quake, in the same home I'm sitting in right now in Riverside County. All we got was a good few jolts. There was no real structural damage in the area. --71.110.8.102 (talk) 06:20, 4 July 2016 (UTC)


 * Here is a Wayback Machine copy of the page the image was taken from. Red indicates "minor to major damage to buildings and their contents", which might be affected by building codes, but yellow indicates "shaking felt, but little or no damage to objects, such as dishes" and so its outer boundary will not be affected by building codes.  (I'll add those explanations to the image's description page.)  The page states that "Earthquakes in the central or eastern United States affect much larger areas than earthquakes of similar magnitude in the western United States", but says nothing about why. --69.159.60.163 (talk) 03:45, 5 July 2016 (UTC)


 * Well, you might as well look at the Virginia 2011 earthquake which was felt from Canada to the southern coast. It was not such a large temblor absolutely, but the crust of the eastern US is very cold, hence solid, hence a good transmittor of what in California wouuld be small, local quakes. μηδείς (talk) 17:48, 4 July 2016 (UTC)


 * We're talking about 'Q' anelastic attenuation factor (or strictly its inverse), the degree to which rocks absorb seismic energy. The rocks of the Laurentian shield have generally high Q and therefore seismic waves are not attenuated quickly. California is a lot more heterogeneous and has a generally much lower Q value. This paper (Figure 11) compares the variation of Q with frequency for different parts of the continental US. The maps of yellow and red by the way are isoseismal maps. Mikenorton (talk) 22:40, 5 July 2016 (UTC)

Finasteride and anabolic steroids
If a person is taking finasteride 1 mg for male pattern baldness and uses steroids for bodybuilding then does finasteride withstand the huge surge of testosterone? — Preceding unsigned comment added by 182.18.177.78 (talk) 10:38, 4 July 2016 (UTC)


 * This is a biology question, not a medical advice question. The biology is pretty interesting - testosterone is converted to the more androgenic dihydrotestosterone by 5-alpha reductase.  It is that last thing, an enzyme, that finasteride actually blocks - the drug is not actually an antagonist of testosterone like cyproterone acetate.  That means that some anabolic steroids - our article lists mesterolone (1α-methyl-DHT) and drostanolone (2α-methyl-DHT) - are analogues of the DHT that is already past the gate finasteride is supposed to guard, and it will have zero effect on them.  (Then again, I don't know that, because biology could throw some crazy curve ball, reacting to the change in testosterone level in some other way!)  Other anabolic steroids, like testosterone, still may interact with finasteride, though honestly I have not done the research needed to see if the enzyme is already converting as much testosterone as it can so that no more can effect it.  Either way, by and large, I expect the large doses and strange forms of steroids will make finasteride pretty irrelevant at stopping their anabolic effects.  Now on the other hand, what about the hair loss?  Well, honestly, I haven't looked it up.  Every artificial steroid has its own chance potentially to interact differently with receptors in the cell, and so while it would seem a good guess that muscle-building and hair-loss effects are in lockstep, I'd have to see empirical evidence to believe it.  And who is going to round up a bunch of balding men to give them dangerous steroids to see if they lose all their hair in a hurry?  Unless I land a job at a POW camp for a very long war, I'm expecting not to figure this one out, though it's possible there's some wince-worthy study buried in the literature. Wnt (talk) 20:38, 4 July 2016 (UTC)

Suggestions for excess solar energy
Hi I have a 5kW solar solution (with 20 panels) but my average usage during the day is about 1.5kW. At night I connect to the grid but have a battery backup if the grid goes down. Originally I was told that excess energy could in future be fed back into the grid, but this is not yet supported in my country by the national energy regulator. In the mean time I would like to make use of all this excess energy and recover some of the costs of this hugely expensive solar investment. Given that I have on average about 2.5kw to 3kW to spare during the day (taking into account losses like shading, time of day and irradiation seasonal differences) - can you guys come up with some ideas to make some recovery money off this? I would be open to an additional smaller investment if necessary. Thank you. Sandman1142 (talk) 11:29, 4 July 2016 (UTC)


 * Could you increase your consumption of electricity? Do you heat and cook with electricity already? Do you have any electrical vehicle? --Hofhof (talk) 12:11, 4 July 2016 (UTC)
 * Oh I forgot to mention I use gas for cooking (low gas usage) and water heating (high gas usage). This was chosen 5 years before deciding on solar. No electric car. Makes sense to do the water heating with solar but I had already invested a lot of money in the gas connection and Rinnai heater which works very well. Sandman1142 (talk) 12:40, 4 July 2016 (UTC)


 * Get a multicooker and a microwave, which are inexpensive and useful.
 * You can save fuel and environment, preheatung the coolant of the combustion engine in the car and charge the battery. Cold start and cold run require increased fuel consumption. Higher valued vehilces built for use in Canada, Alaska, Siberia, Scandinavia and Iceland are equipped with it, but the savings might be not that high. It requieres an electric coolant pump. Anyway in Winter, then not too early for sun rise, You would not have the need to scrap the ice from the windshield. But it would require expensive batteries, to store the electricity over night for the next morning. Also the lifetime of batteries is limited.
 * If You can, have the freezer of the refirgerator going lower to save the bought electricity over night. Never use washing machine, dryer and dishwasher over night, just pre wash, if neccessary.
 * A geothermal heat pump will exceed the power of Your solar panels, but if You own a air condition which is designed to use the its heat pump in reverse for heating the room, it might heat up to double efficient than a conventional heating resistor. Some air conditions only have a conventional heater installed. There are no further savings on energy. But if the air condition is able to operate the pump by switching radiator and condensor each other, it just cools the atmosphere outside and pumps the heat into the room, saving energy compared to a conventional heater.
 * Power to gas units are not avail in a 5 kWh range and do not work efficient, but produce gas from water and electric energy. Often the units produce hydrogen only, but methane is requried for the gas grid. Gasoline cars can be modified to switch to a propane and buthane mix in ratios of 40/60% and 60/40% when the cold run finished, only. The 40/60 ratios are swapped by summer/winter season, due any engine damage. The engine needs to startup with gasoline.
 * In Germany the electic companies are required by law to buy up to 10 kWh per customer. -- Hans Haase (有问题吗) 14:26, 4 July 2016 (UTC)


 * You could join distributed computing projects. See List of distributed computing projects. You get a chance of making a discovery (many such discoverers are mentioned in Wikipedia) or contributing to a shared effort. I don't know whether any projects offer payment apart from a tiny prize chance in Great Internet Mersenne Prime Search (GIMPS). If you pay for electricity then the cost is many times larger than the expected prize money. PrimeHunter (talk) 15:01, 4 July 2016 (UTC)


 * Mining of bitcoin which requires a sizeable investment in computing hardware to perform "proof of work" is a way to convert surplus electric power to an income in Cryptocurrency. AllBestFaith (talk) 16:02, 4 July 2016 (UTC)
 * What a coincidence you should say this! I literally 10 minutes ago listened to the NPR podcast Planet Money which was talking about bitcoin mining. It also talks about the main issue in bitcoins right now - the fact that bitcoins aren't transferring.


 * Whoever gets a good solution to this should move to Germany and get rich. This is becoming a serious problem in Germany, a country with lots of solar, where the grid sees inverse spikes when the sun pops from behind a cloud.
 * For South Africa, can you look at cold banking? Producing cold during excess capacity and making use of that through an aircon system?  All of these solar energy storage systems are needing to develop as local solutions for local climates. What's right for Spain or Germany isn't necessarily the right thing for South Africa. Andy Dingley (talk) 11:30, 5 July 2016 (UTC)
 * Thanks everyone for the replies. Producing cold or extra heat is a bit of a conundrum, because we are typically at work during the peak solar periods. We will only need the aircon or water heating or oven when are back home and that is around sunset or after.  Bitcoin mining is interesting but I believe you need some serious hardware just to get a chance of solving one; a normal PC will not cope.  I am considering an electrical water heater on the other side of house and then running the gas heater on the original side. Do you call these things geysers too?  Wish I lived in Germany but here in Africa things move sloooowly. I was also considering running some sort of high energy manufacturing machines in my garage during the day... Sandman1142 (talk) 11:46, 5 July 2016 (UTC)
 * Sandman1142, before You think Germany is a paradise. No, Germany is a paradise for crimal people. Heating up water is not efficient with electric solar, only. Solar cells convert less than 20 % electric power for the light input. Thermal solar collectors can preheat the water, sometimes hot enough, else reaching the needed temperature can be done by gas or electric. Prices for electric energy have increased in Germany, but are still cheap. Never the less several thousands were cut form electricity due unable to pay the bill. Gasoline is expensive, diesel is taxed lower. Never the less in Germany, false information is spread about automotive technic, especially about hybrid vehicles. One of the suggested lies is, Plug-in hybrid vehicles were unable to drive when batteries could not be charged from the grid. The truth is, charging the battery is cheap, but the vehicle gernerates its own electric power from a generator and convert the brake power. In the US, rumors about "free energy" are spread arround. While a policical decission ruined most of the German solar industry, now the Chinese do a good job. Wikipedia has no article about. It is not mentioned in 2011 in Germany and Solar power in Germany, but still have a vision about Desertec. -- Hans Haase (有问题吗) 00:39, 6 July 2016 (UTC)

UV incidence
What's the difference between UV incidence in the shadow and direct exposure to the sun? For example, if you are in a street and one side is sunny while the other is shadowy. How much would the UV rays bounce to the shadow?--Hofhof (talk) 11:58, 4 July 2016 (UTC)


 * Visible light can be measured in units of lux; have a a look at radiometry to review all the different ways we can measure "amount of light." For ultraviolet light, we typically prefer to use a different unit.  (Are we counting photons?  Watts?  Integrating watts over wavelengths?  Estimating perceptual brightness to the human eye?  Using some type of dosimetry to estimate health impact? ... and so forth).  The original question was phrased in terms of "incidence" - so we might reasonably assume that we want to use Illuminance ... but because we're talking about the UV spectrum, there is definitionally zero ultraviolet illuminance in the sun and in the shade!  The standard unit only measures visible light.  This makes sense - your human eye sees the exact same amount of ultraviolet light whether you stand in the sun or in the shade - and that's what "incidence" measures in the SI system of units.
 * In the visible spectrum, our article on lux § illuminance estimates anywhere from 10 to 100 times more light - in units of lux - in direct sunlight than in shade. It is reasonable to assume approximately the same ratio between direct sun and shade for invisible near-ultra-violet light; it won't be exactly the same, because various materials and surfaces reflect and disperse UV and visible light differently - but it's a good ballpark estimate.  More to the point, we rarely use lux for the ultraviolet portion of the spectrum - these special units of measurement only correctly apply to the visible spectrum of light.  If you want more precise measures, it will help to start by refining the search based on how you want to measure the amount of ultraviolet light.  In other words, which type of unit are you looking for?
 * For the scientifically inclined reader: this website - the personal website of one Pat Arnott, a professor, researcher, and enthusiast of satellite remote-sensing, hosts a 1987 JGR publication on the reflectivity and transmittivity properties of Earth's atmosphere in the ultraviolet spectrum. That'll probably give you all the math you need to completely constrain the incident power in most parts of the Ultraviolet spectrum, on Earth, in various weather conditions.  You might not even want to answer your original question unless you're the kind of person who finds this type of sentence attractive: "the directional albedo A of a Rayleigh scattering atmosphere of optical depth τ bounded by an opaque lambertian surface of reflectivity R is given by... (massive equation)."
 * Nimur (talk) 12:50, 4 July 2016 (UTC)


 * Here's another source, from a dosimetry standpoint: Penetration of solar erythemal UV radiation in the shade of two common Australian trees. (1999).  That source indicates that UV dosage, as pertaining to its health effects on human skin, measured in the shade provided under a tree was 37% to 55% of the dosage in direct sunlight.  Here's a more recent review article, Human exposure to solar ultraviolet radiation (2001).  Both articles provide lots of additional citations.   Nimur (talk) 15:33, 4 July 2016 (UTC)


 * The article Ultraviolet photography provides a link to these ultraviolet street scenes. Images photographed in ultraviolet light must be presented in a false monochrome or colours. AllBestFaith (talk) 15:48, 4 July 2016 (UTC)
 * Rayleigh scattering preferentially affects shorter wavelengths, so that diffuse light (which is what makes it into shadows) is relatively enriched in UV. An interesting article is available here. Shock Brigade Harvester Boris (talk) 03:51, 5 July 2016 (UTC)

The die is cast
Until reading out article on alea iacta est, I assumed that "die" referred to a Die (manufacturing) after the process of casting, when it's too late to make another design, not to half of a pair of dice that had been thrown. Was the use of metal dies (in any form, regardless of how primitive) known to the Romans in Cæsar's day? The article has no history of dies, and it's really hard to run a search when the term "die" is so commonly used for other concepts. Nyttend (talk) 13:21, 4 July 2016 (UTC)
 * The way I learned the history of technology, machine tools - and specifically, the use of metal die tooling - are an amazingly new invention, circa 1800 AD - in the earliest days of the steam-engine. Earlier metalworking used forging, casting, brazing, but never punching or tooling.  It's hard to specifically cite the non-existence of older machine tools... but that's how I've always seen things laid out in history museums.  For example, the British Science Museum has an excellent collection of industrial tools and there is a marked transition in their exhibit on steam power, where the first metal machine tools are found.  Episode #5 of Series One of James Burke's Connections described the connection between the rifle, the cotton gin, and subsequent invention of machine tools and dies in the 1790s.
 * It might be worthwhile to find a good dictionary and review the etymologies for the word "die" - there's surely some significant information buried in the fact that the Latin word is not like our word, but I'm not enough of a linguist to interpret that signal.
 * Nimur (talk) 13:40, 4 July 2016 (UTC)


 * According to the Oxford English Dictionary, the source of English "die" is surprisingly the Latin "datum" meaning "given". They say "it is inferred that, in late popular Latin, datum was taken in the sense 'that which is given or decreed (sc. by lot or fortune)', and was so applied to the dice by which this was determined."  The meaning "an engraved stamp used for impressing a design upon some softer material" is first attested in 1699 although there's no indication of how this transfer of sense occurred.  According to Wiktionary, the Latin "alea" originally meant "pivot-bone or joint-bone, since bones were used for early dice" and derives from "axis".  CodeTalker (talk) 14:44, 4 July 2016 (UTC)


 * The article linked above is pretty clear, tracing the phrase back to a Greek phrase in which the key word is κύβος, which is to say, a "cube" or six-sided die. Wnt (talk) 20:14, 4 July 2016 (UTC)
 * Hammered coinage claims the earliest coins (first millennium BC) were made by hammering on a planchet placed between two dies. No clue where the word comes from, however. Thincat (talk) 21:09, 4 July 2016 (UTC)
 * That's factually accurate, but the words you are using, such as "coin" are very recent, not Greek or Latin. Originally, knuckle bones were used as dice. μηδείς (talk) 22:29, 7 July 2016 (UTC)

Why are thorium and uranium so stable?
232Th and 238U have half-lives of billions of years, while everything else in that region decays away in at most millions (235U, 236U, 237Np, 244Pu, 247Cm), and most likely not even that. I assume there is a nuclear shell closure going on here, but where can I find a less vague, more detailed explanation? Double sharp (talk) 14:52, 4 July 2016 (UTC)
 * Stable nuclide. AllBestFaith (talk) 15:30, 4 July 2016 (UTC)
 * I'm well aware of that article, but thorium and uranium are not actually absolutely stable like the nuclides discussed there are. They are, on the other hand, relatively much more stable than the neighbouring elements, and my question was why they decay as slowly as they do. Double sharp (talk) 15:37, 4 July 2016 (UTC)
 * Because they are within one of islands of stability. Ruslik_ Zero 16:18, 4 July 2016 (UTC)


 * As far as I am aware, la Isla de estabilidad is an award-winning novel by Umberto Eco. Its existence is more expected than it is an explanation. μηδείς (talk) 17:22, 4 July 2016 (UTC)
 * Are you talking about L'isola del giorno prima? --Trovatore (talk) 23:08, 7 July 2016 (UTC)
 * The article has a bare-bones explanation:
 * The hypothesis is based upon the nuclear shell model, which implies that the atomic nucleus is built up in "shells" in a manner similar to the structure of the much larger electron shells in atoms. In both cases, shells are just groups of quantum energy levels that are relatively close to each other. Energy levels from quantum states in two different shells will be separated by a relatively large energy gap. So when the number of neutrons and protons completely fills the energy levels of a given shell in the nucleus, the binding energy per nucleon will reach a local maximum and thus that particular configuration will have a longer lifetime than nearby isotopes that do not possess filled shells.
 * Of course it's far from a complete explanation, more of a starting point. Presumably you can use the references in the article and follow the thread as far as the state of human knowledge currently allows. --Trovatore (talk) 20:23, 4 July 2016 (UTC)


 * A very accurate universal decay law was recently discovered, see here for details. Count Iblis (talk) 22:03, 4 July 2016 (UTC)


 * If only it were written in ENGLISH! Otherwise, it seems cool, but it's tooo effin'ard to understand. μηδείς (talk) 02:55, 5 July 2016 (UTC)


 * This book https://www.amazon.com/Elements-Their-Origin-Abundance-Distribution/dp/019855298X goes into the nuclear shell theory, it is most certainly among the 10 most brilliantly written and edifying books I have ever read. μηδείς (talk) 22:54, 7 July 2016 (UTC)