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July 12

Why an even 100 mg/dL as blood glucose standard?

It seems rather a large coincidence that the standard American expected blood sugar level should center on 100 mg/dL. Is this just a rounded number? An average? A statistical artifact (i.e., sig. fig.s?) Can anyone point out where this number originated. (To stave of certain unnecessary clarifications, I am well aware there are various ranges, such as 70-100 for fasting non-diabetics, 90-130 for controlled diabetics, etc. I am only interested in the origin of the 100 mg/dL, and don't need the other mechanics explained.) Thanks. μηδείς (talk) 01:00, 12 July 2015 (UTC)

I tried really hard to find this, but failed so far. The various medical associations that state a standard blood glucose concentration don't make it obvious where they get that advice. In the literature, I have yet to find a paper or review that established rather than merely mentioned a blood glucose standard. Papers stating a blood glucose standard go back to 1911 at the very least, so I'd imagine the paper(s) that established the 100mg/dL or 70-130mg/dL standard may be very very old. If there is a more recent work to reinforce that this should be standard, I haven't found it. Someguy1221 (talk) 02:20, 12 July 2015 (UTC)

It is based on observed fasting glucose levels of nondiabetics and is a coincidence. Edison (talk) 13:52, 12 July 2015 (UTC)

I tend to suspect that's true, but do you have a source, or can you at least say "as I remember from medical school"? I am pretty good at speculation on my own, so I was hoping for something at least historically that explains this number. μηδείς (talk) 17:12, 12 July 2015 (UTC)

This paper looking at over half a million patients at least reinforces the claim that 70-100mg/dL is relatively low-risk. Individual studies vary in which specific cutoffs they conclude with, and that makes sense due to different study populations and different risks being evaluated. What I do notice, Medeis, and what I suspect belies the round numbers, is binning. All of the papers I've been finding looking at large numbers of patients invariably chose to bin their data before doing any statistical analysis. The choice of binning is of course arbitrary, and the authors always choose round-number cutoffs. Some groups produce non-round values of mg/dL, but only because they were using round molar values. What is consistent between almost all publications is that 100mg/dL is always inside the lowest-risk bin. The rare exception seems to be studies concerning the elderly, some of which have 90mg/dL as the center of the safest bin, and 100mg/dL in an elevated risk bin. But anyway, yeah, BINNING. That is your answer (I suspect, anyway. I still haven't found the study(s) explicitly stated as having established the standard). Someguy1221 (talk) 23:59, 13 July 2015 (UTC)

I saw my endocrinologist today and she is newly finished interning, so not too many years out of school. She gave me a blank stare, until I finally compared the number to 98.6F as the "normal" body temperature. Then she said that there are a choice of ranges, and that 100 was a number based on averages that was close enough to normal that it is used for convenience. She didn't say data binning, but I understand the concept. Thanks for the assistance. μηδείς (talk) 00:40, 14 July 2015 (UTC)

Ferromagnetism

Why are magnetic field lines nearly always normal to the surface of a ferromagnet at every point? Yes, this is a homework question, and yes, I tried to figure it out but I can't. Yashowardhani (talk) 03:12, 12 July 2015 (UTC)

If there exists any component of the magnetic field that is tangential to the surface, that implies that there also exists a current flowing in the surface (either an actual flow of charge, or a displacement current, appropriately chosen to correspond to the magnetic field). You can verify this using the right hand rule; or, if you are a little bit more mathematically inclined, you can apply Maxwell's equations and see for yourself. This can occur in the real world (it is not "unphysical"); but it is not a typical characteristic of what we call a ferromagnet. It's much more plausible to see that kind of behavior in an active device that is expending energy to cause current to flow (like an antenna driven by an electric circuit).

Here's a lecture note from MIT's OpenCourseWare on boundary conditions in electromagnetics for your review.

Nimur (talk) 09:04, 12 July 2015 (UTC)

Wow thats what you call a model answer. I dont know if there are any prizes for good answers, but if there were i would give you one!! --86.176.9.176 (talk) 21:02, 12 July 2015 (UTC)

Difference in flight time between SEA-HKG and YVR-HKG

Googling "yvr hkg" gets me "...13h 10m duration", while googling "sea hkg" says "14h 5m duration". That's almost an hour of difference. Why the huge difference? YVR and SEA is only about 200km apart, plus that 200km is (close to) orthogonal to the flight path. My other car is a cadr (talk) 06:00, 12 July 2015 (UTC)

Looking only at the lowest-cost flights, which appear first, the shorter flights are all serviced by B777s and the longer one by A330s. I conclude that the B777s are flying roughly 7% faster than the A330s, and both are flying at their best fuel economy speed. On the other hand, given that our articles show cruise speeds of 560 mph and 541 mph, not a 7% difference, I could easily be concluding incorrectly and there may be other factors involved that I'm not aware of. ―Mandruss ☎ 06:22, 12 July 2015 (UTC)

Thanks.My other car is a cadr (talk) 06:32, 12 July 2015 (UTC)

To correct myself, the 200km is actually parallel to the great circle route flight path, so that definitely added some flight time (about 10 to 15 minutes). My other car is a cadr (talk) 06:32, 12 July 2015 (UTC)

Yes, according to gcmap.com the distances are 10287 and 10460 km, so Seattle is 1.68% farther. If the 777 cruises at 560 mph vs. 541 mph for the A330, that's a 3.51% difference. That leaves only 1.62% unaccounted for, or about 12 minutes. I could see the difference in taxiing time between one and another airport being that large, though I don't know about those specific airports. --174.88.135.232 (talk) 09:45, 12 July 2015 (UTC)

There also appears to be some rounding going on, to the nearest 5 minutes. That could randomly add or subtract a few minutes. StuRat (talk) 21:15, 12 July 2015 (UTC)

You're looking at the scheduled flight durations, but it turns out that the average true flight durations, comparing YVR-HKG and SEA-HKG are much closer. The website flightstats.com shows ratings of 0 to 5 stars in three categories for each flight: on-time performance, delay performance, and overall performance (which is a combination of the other two). Here's what I found on that web site, in the "overall performance" category:

• Delta 281 SEA-HKG 4.7 stars [1]
• Air Canada 7 YVR-HKG 1 star [2]
• Cathay Pacific 889 YVR-HKG 0.1 stars [3]
• Cathay Pacific 837 YVR-HKG 0.3 stars [4]

The Delta SEA-HKG flight is usually on time, while the YVR-HKG flights are frequently late. I can think of three possible reasons for this:

(1) There is a systemic problem at YVR airport such that transpacific flights are often late to take off, resulting in late arrivals, compared to SEA airport; or

(2) The schedulers at Air Canada and Cathay Pacific are, either in general or for all transpacific routes, more optimistic than the schedulers at Delta; or

(3) For this specific route, the schedulers at Air Canada and Cathay Pacific are more optimistic than those at Delta.

I would conjecture that the true explanation is (3), and there is a simple economic rationale: Delta has the only daily nonstop flight from Seattle to Hong Kong and therefore it has no incentive to be optimistic in the scheduled flying time (i.e. it would not attract any additional business by shaving 10 or 20 minutes off its posted travel time on those flights). By contrast, Air Canada and Cathay Pacific are in competition on the YVR-HKG route, and for some travellers, a difference of 10 or 20 minutes in the posted travel time might be the deciding factor in which airline they choose. Mathew5000 (talk) 08:04, 17 July 2015 (UTC)

Coneflower (Echinacea purpurea) identification

Can anyone tell me which cultivar of Coneflower (Echinacea purpurea) is the flower in this photo? Thanks --Captain-tucker (talk) 10:10, 12 July 2015 (UTC)

Coral Reef looks like a good match. Richard Avery (talk) 06:37, 13 July 2015 (UTC)

Thank you! --Captain-tucker (talk) 08:51, 13 July 2015 (UTC)

Protecting a hard drive

How might one protect a hard disk drive and a floppy disk from the Solar storm of 1859? Assuming modern materials available. Would putting them inside an idle microwave (acting as a faraday cage) protect them? — Preceding unsigned comment added by 2001:DA8:D800:87:12BF:48FF:FEE2:10BA (talk) 12:59, 12 July 2015 (UTC)

The storm in question was notable for producing induced high electric voltages on telegraph lines and the article also mentions it was detected on a magnetometer. That does not mean that the magnetism was so strong that it would have magnetized or demagnetized ferromagnetic media, or caused all steel objects in a room to fly up to the ceiling like in a cartoon. I have observed hard drives and floppies surviving being in the same room with electromagnets, transformers, inductors, motors, and powerful permanent magnets. A box made of copper or aluminum screen wire could function as a Faraday cage and shield against electric fields or radio waves, but would not screen against the field of a relatively slow changing but strong magnetic field. A steel or iron box, on the other hand, would shield against a magnet pretty well. A relatively thin steel shell isolates against a fairly strong magnet, from observation with permanent magnets, coffee cans, and compasses. The ,microwave is designed to shield against very high frequency electromagnetic waves, and not to shield against strong but slowly changing magnetic fields. The steel walls of a microwave might be a good shield against a steady magnetic field, but I have doubts about the screen in the window. Edison (talk) 13:36, 12 July 2015 (UTC)

I know this might sound silly, but would a modern car be considered a faraday cage? If lightning struck the car and your cell phone was inside (and all the windows up door closed etc) the cell phone would function just fine. So incase of another Solar storm should we throw all of our computers in our cars? (I know this is facetious but good intentions I assure you) Void burn (talk) 21:01, 14 July 2015 (UTC)

How can the butterfly effect be detected using the scientific method?

Throwing dice we can slightly alter the initial conditions and see whether this produces a quite different outcome.

However, if someone claims that the same happens to the weather, how could someone prove or dismiss the claim? You can observe change in infinitesimal small starting conditions (butterfly beating its wings, but also many other factors), and you can observe different outcomes in weather prediction.

How can you prove that the small initial variation influences the outcome? --YX-1000A (talk) 15:42, 12 July 2015 (UTC)

Here is the answer. We know for a fact that computer systems that predicts the weather suffers from the butterfly effect where tiny initial differences in the intial conditions will lead to huge differences in weather prediction outcomes. However this DOES NOT PROVE that the butterfly effect exists for real weather, it only shows that it exists for computer simulation of the weather.

The only way to prove with ABSOLUTE CERTAINTY that the real weather suffers from the butterfly effect is to use a time machine capable of traveling to the past. We need a Tardis

However all is not lost. You can built a physical device called Double pendulum. This device has a chaotic behaviour in its motion. For certain, initial conditions, it will never have the same trajectory twice because it suffers from the butterfly effect. Because it is a real physical device, it proves scientifically that the butterfly effect is real for a physical system. This increase the confidence that another real physical system, the weather also has the butterfly effect. 220.239.43.253 (talk) 15:56, 12 July 2015 (UTC)

• No, your experiment with the pendulum won't increase the confidence that the butterfly effect is real for physical systems, unless they are very simple physical systems. That's similar to a die. You can demonstrate that the result of throwing one die is strongly influenced by the initial conditions. If you were to throw 1,000 dice, the result would be more or less the same no matter what you do.--YX-1000A (talk) 16:19, 12 July 2015 (UTC)

In science, we rarely prove anything. Instead, we provide convincing evidence and make statements with great confidence. Your question contains two key phrases: the scientific method, and the word "prove" (in the context of applied mathematics). These are two very different things! In science, we use evidence to test hypotheses, refining a theory until it matches observation, demonstrating that a result is consistent. In mathematics, we apply formal rules to axiomatic principles to prove that a result is consistent.

In the case of proving mathematical instability, we start with a definition of stability that is relevant to this context (for example, we expect a smoothly-varying partial derivative for any equation that governs natural behavior). If a sophisticated equation is used to model a weather prediction, we can perform a sensitivity analysis directly on the equation (or use a numerical method to approximate this analysis). When you read the historical publications that forged the basis of what we today loosely call "chaos theory" or "the butterfly effect," you can see that most of the emphasis is on mathematical analysis, and not empircal or observational science. In pure mathematics, we can prove that a particular equation is unstable, for some definition of stability!

In the case of demonstrating the "the butterfly effect," the demonstration is applied to a mathematical model of weather rather than to "the weather" itself. The scientific task is to determine if this equation actually describes the real world. We collect data, using controlled experiment, to test whether the equation has predictive power. In particular, because we know that the equation has poor predictive power, we must be very careful in the formulation of a testable hypothesis. For example, the equation might be unpredictable in the time domain, but it can have powerful and testable consequences in the frequency domain; or in some other transform domain. This is one reason why phase space plots are so useful when we study chaotic systems.

Whether the mathematical model applies to the real world is a separate question, and is not actually a matter of proof! All we can do is provide a compelling argument, guided by observation, to strongly conclude that the mathematical model matches the data.

Nimur (talk) 15:59, 12 July 2015 (UTC)

So, can I conclude that: we have a set of equations that model weather, and these equation are both very sensitive to initial conditions, and, the best match to empirical data that we have. And, there is no empirical evidence against the possibility of developing a complete different set of equations in the future that match empirical data even better (that means, better predictions, at lest under some aspect) but are completely insensitive to small changes in input data.

But, coming back to the empirical method. Would this be a valid empirical experiment?

what would happen if I try to predict the weather one year long using a given model, and, the next year I fire a furnace on my garden every day, and try to predict weather all year long again with the same model. If my predictions don't vary, would that mean that small changes are to be ignored? What if I do alternatively year after year, would we come to a point where we admit that little stuff is irrelevant (or simply compensate by other little stuff)?

--YX-1000A (talk) 16:27, 12 July 2015 (UTC)

Mathematics can provide a model of reality but mathematical model of reality is NOT REALITY. So whatever the mathematical model proves is not prove that it is the EXACT SAME as reality. For example: Newtonian Physics is a mathematical model of reality but it is not reality. So whatever mathematical model physicists has today is most likely NOT REALITY either. 220.239.43.253 (talk) 16:39, 12 July 2015 (UTC)

• That was not the question here. The question was what part of reality to include as input to the model, and what to ignore as irrelevant. --YX-1000A (talk) 20:56, 12 July 2015 (UTC)

Sure - it's a model for reality, and sometimes it has a practical purpose with predictive power. Consider the 100-year flood model. Civil engineers, city planners, home buyers, and insurance agencies use the hundred year flood model to determine risk, evaluate building safety, and weigh costs against risks. The hundred year flood is a model of weather (and other scientific elements of hydrology): it uses mathematical analysis and statistics, guided by observational data, to estimate a probability of flood. But it doesn't even try to predict when that flood will happen! The model is useful: we know which terrain is suitable to build on. We can estimate with great confidence that any specific hilltop might be covered by water at least once between now and 2115. But the model does not try to tell you what year, month, or day the rain storm will happen! We have no mathematical model telling us when it will rain over the next hundred years. Any such model is subject to terrible over-parameterization and unstable, chaotic behavior. But we can still make other useful long-term predictions about the weather.

To understand "chaos theory," or complex systems in general, you need to develop a great mathematical modeling toolkit, complete with some calculus, statistics, numerical methods, and a study of many example problems in physics. A great error in the popular-science version of "chaos theory" is to present the undisicplined version of the problem-statement: a bug flies around, and suddenly the entire universe is completely unpredictable! This is a ludicrous representation of the problem, and it's an even more ludicrous representation of the way that real mathematicians and physicists think about it. Nimur (talk) 17:43, 12 July 2015 (UTC)

One important thing is to emphasize that outputs become inputs. An analogy that we use (in our freshman intro class with no math or science prerequisites...) is a complicated shot in pool (billiards). You make a shot and the movement of the first ball becomes the input for the second ball, which becomes the input for the third ball, and so on. A tiny error in where the cue strikes the first ball can eventually decide whether you sink the ball. Short Brigade Harvester Boris (talk) 21:27, 12 July 2015 (UTC)

Right, that's propagation of uncertainty, with emphasis on propagation. Anything that propagates - like a recurrence relation or a differential equation - is susceptible to the problem. You can consider an idealized billiard table as a series of discrete collisions, whose inputs and output parameters are connected together by a discrete recurrence equation. The parameters - position and velocity - for all n billiard balls can be represented as a giant vector or matrix; the collisions can be written as a matrix operator; and the quality of "chaos" can be explored by observing the divergence of the Jacobian of the iterated collision operator. Or, you can intuitively interpret the problem and just watch how the collisions cause the balls to fly off in apparently-random directions! Nimur (talk) 22:22, 12 July 2015 (UTC)

Something like that is already used to improve weather predictions. The initial conditions of the simulations are varied and if the outcome doesn't change much then they can predict the weather further in advance. If varying the initial conditions slightly leads the simulation to quite different outcomes then they can only predict reasonably accurately a short time in advance. The predictions are quite accurate when qualified by the length of time and which aspects of the weather they estimate they will be accurate. Dmcq (talk) 17:10, 12 July 2015 (UTC)

It's clear that meteorologists will ignore the bugs flying around that Nimur points at above. But what is, for meteorology, "too small to bother?" Meteorologists will ignore forest fairies, until empirical evidence appears that indicates they can affect the weather if annoyed. Would they also ignore man-made behavior like energy consumption in the last days when predicting the chances of rain in the next days? What, who and how they decide what data get plugged into their predictive weather models as parameters? --YX-1000A (talk) 20:56, 12 July 2015 (UTC)

Well, a meteorologist is the exact professional who produces weather prognostications, and they make such a judgement call. Anybody who uses a weather report - farmers, aviators, sailors, surfers, beach-goers... all decide what data to trust, and how much confidence to place in the predictions. At the extremes, when there is significant risk to an incorrect weather prediction (as may be the case for some aviation weather applications), the bar is set much higher for confidence in predictions.

If you want to read about how modern weather prediction is performed by the United States National Weather Service, you can visit their Model Analyses and Guidance website (which is a little bit technical: the Product Description Document is a good place to start getting oriented). There are many products (i.e., many types of prediction models). For many, human activity is not a factor - I doubt that there's any human activity index input to the mesoscale precipitation forecast, for example. Other predictions - like the air quality index - certainly account for predictions of human activity. Such forecasts are used, for example, to produce Air Quality predictions and smog alerts. Here is an overview of specific human-factors data and measurements used in the Air Quality Model.

If you're totally lost, a theoretical introduction to meteorology is called for. A few great introductory books that are available at no cost include Aviation Weather, (which has some fun cartoons scattered throughout).

Most people let a TV-meteorologist reduce their weather forecasts to a much simpler data product: "partly sunny" or "chance of rain." At such a coarse granularity, the predictive power is quite weak and the forecast-model is completely hidden from your view, so you don't know what went into it. Usually, the only people who really deal with the quantitative details are people who care a lot about weather: pilots, sailors, farmers, meteorologists, and applied physics enthusiasts.

Nimur (talk) 22:41, 12 July 2015 (UTC)

Models for numerical weather prediction aren't made from fits to data, but are based to the greatest extent possible on fundamental physical laws. The core of a NWP model is Newton's second law of motion, the first law of thermodynamics, and conservation of mass. These equations when coupled do indeed exhibit chaotic behavior. If someone can come up with a an alternative physical framework that does not use these equations I'd be most interested to know. Short Brigade Harvester Boris (talk) 21:15, 12 July 2015 (UTC)

• @YX-1000A: Some key info I don't think anyone has posted: the so-called "butterfly effect" can be formalized and even quantified in terms of the Lyapunov exponent of a dynamical system. If you are curious about how such a thing could be measured from real-world data or experiments, see e.g. these peer-reviewed publications (should be accessible) [5] [6] [7]. The first,DETERMINING LYAPUNOV EXPONENTS FROM A TIME SERIES is published in the highly reputable Physica, and should serve as a highly authoritative starting point for understanding how scientists detect and quantify "butterfly effects" in real-world systems. In regards to the previous discussion - these analyses would not be derived from a model, but derived from data. No need to get in to full-fledged weather prediction - even the simple logistic model will display deterministic chaos (remember, biology was the other key historical science that motivated chaos theory as a discipline). If you're interested in that angle, you'll get plenty of hits searching google scholar for /lyapunov exponent population/, with many applications of the above methods for very specific real systems - [8] SemanticMantis (talk) 13:47, 13 July 2015 (UTC)

Is fog harvesting impossible too far inland?

All the projects for harvesting water from fog that I've seen (admittedly on a very cursory inspection) seem to take place fairly close to the sea ([9], [10], [11], [12]). Is fog absent too far inland? How come none of those projects take place say in the middle of the Sahara or in the Gobi desert? Is there a difference between absence of humidity and absence of fog? For example the Atacama desert, one of the driest places on earth (I suspect that is defined as minimal rainfall, not average humidity of the air?), seems nevertheless to have enough fog to make a fog harvesting project worthwhile at least in theory. (Although the WP article says in practice it was a failure.) Thank you for any information clarifying this interesting topic. Contact Basemetal here 20:00, 12 July 2015 (UTC)

There might be a language issue here. "Fog" normally refers to visible water droplets in the air. The air always has some humidity, even in a desert, but it doesn't always form those visible water droplets. One advantage of a desert is that temperatures drop very low at night, due to a lack of cloud cover to keep the heat in. Thus, even though humidity and thus the dew point are low, the temperature can still drop below it, and you can get dew. So, that dew can be collected, say using a large tarp over an inverted cone dripping into a bottle. This only produces a rather small amount of water, so perhaps enough for survival, but not enough for household needs, like bathing, cooking, washing clothes, etc. (You could theoretically make hundreds of such rigs to collect enough water for all that, but this would be rather impractical, as it would all be damaged in the first sandstorm.) StuRat (talk) 21:07, 12 July 2015 (UTC)

Are you saying the references I gave do not know the difference between fog and dew? Contact Basemetal here 21:33, 12 July 2015 (UTC)

No, only that, while the process is similar, it's likely to be done on a smaller scale in the desert, as a survival method rather than a permanent source of water, and have a different name. It's like the difference between an oven and a camp stove. StuRat (talk) 21:37, 12 July 2015 (UTC)

BTW, one of those sources said that water collected that way doesn't need to be filtered or processed in any way. I'm not so sure about that. Bacteria and dust will be collected, too, and boiling it or otherwise disinfecting it seems like the safe thing to do. StuRat (talk) 21:44, 12 July 2015 (UTC)

I am still baffled. Why is none of those projects in the middle of the Sahara? Don't they need water there? It can't be humidity level per se since the Atacama desert is extremely dry, yet there was such a project in the Atacama desert. What makes such a project viable in the driest place on earth but not in the middle of the Sahara? Any ideas? Contact Basemetal here 22:13, 12 July 2015 (UTC)

Noting your use of the word was, I suspect that the Atacama desert project wasn't viable after all. You would need a lot of those collectors, each collecting only a few ounces of water in that low humidity. Then there's the issue of how to collect that all into a sealed reservoir. You'd either need lots of pipes, or to collect it manually by dumping little jars of water into larger ones and delivering those to the reservoir. Then, as I mentioned, the collectors would need frequent maintenance after sandstorms or just normal wind. After doing this you still wouldn't have nearly enough water for agriculture, so how exactly would the people there make a living ? Perhaps if they were miners and there was a rich mineral wealth there, that might make some sense, but they would still need to build all the other infrastructure needed, like roads. I suspect that in such a scenario, the area would become a ghost town as soon as the mineral wealth was gone. StuRat (talk) 02:05, 13 July 2015 (UTC)

[citation needed]. Looking at [13], it seems viable enough to have plants growing. And the people behind it say that when they have enough, they will change the face of Arrakis. :) Seriously - but I'm only guessing here - I would distinguish between two measures of the "dryness" of a desert. One is the amount of rainfall; the other is the relative humidity. Atacama gets a lot of fog, which means it must have pretty high humidity levels on frequent occasion; it is merely in a double rain shadow that prevents drops of water from falling. So if you could tip the balance a bit, you might get somewhere. It's possible that a large continental desert like the Sahara, receiving winds from all directions but generally dried out by air descending from the high atmosphere and warming up, might have a lower average humidity even while getting more millimeters of rain in the gauge. But that's a guess. Wnt (talk) 20:20, 15 July 2015 (UTC)

The fog indicates high relative humidity, but that mostly means low temperatures, so the little humidity in the air forms fog. They claim it can be scaled up, but I'm rather skeptical. After all, each fog fence removes some of the small amount of water from the air, so a million fog fences won't get you a million times as much water. I'm reminded of the merry-go-round water pumps in Africa, which were supposed to pump water as children played on them. Sounded good at the time, but the kids got tired of them (not much fun because they don't spin long, due to the drag of running the pumps) and there was no way to fix them once they broke. I suspect something similar happens here, where, as long as some charity is footing the bill to maintain the fog fences, then the locals will be happy to get the free water. But, once they have to pay the costs, it will no longer be worth it. StuRat (talk) 21:09, 15 July 2015 (UTC)

I would be quite amazed if humans can dehumidify the outdoor air with a simple construction project, even if there is one in every town. (If they can do that, maybe they should build these things in wet, humid areas to make them more comfortable...) I read Fog collection which narrates the tale in Chungungo sort of how you describe, but on a search I found [14] which says the collectors went out of use in 2000 after the government built a desalination plant. (AFAICT the desalination plant provided water at government expense, whereas the fog catchers remained a local project, so there was no local financial motivation to keep them going, but I'm inferring based on a few vague sentences) Wnt (talk) 23:18, 15 July 2015 (UTC)

"One in every town" ? Wouldn't they need thousands in every town to provide for the town's water needs ? According to your link, 12 fog collectors produced 2000 liters per day. That's under 17 liters per fog collector per day, and presumably only that much in ideal locations. Certainly not enough water for a town, and not enough for agriculture, either. Your link also says they had "funding from the Global Environment Facility", so not local funding. StuRat (talk) 00:25, 16 July 2015 (UTC)

The articles shown don't explain what the difference is between one of these "fog collector" machines and a dehumidifier. Both extract water from the air. Both work well in high humidity and do nearly nothing in low humidity. 199.15.144.250 (talk) 12:40, 13 July 2015 (UTC)

A dehumidifier typically uses electricity to remove most of the humidity from a small room, while a fog collector uses no electricity and collects only a small portion of the humidity from an outdoors area. StuRat (talk) 12:58, 13 July 2015 (UTC)

July 13

What species is this?

I added these photos to cicada but they were removed because I don't know what species they are (and there is no insect inside). What species is this? They are common in south Georgia, US and this one is from near the Atlantic coast. Bubba73 ^{You talkin' to me?} 01:02, 13 July 2015 (UTC)

Based off of just location, Neotibicen auletes, Neotibicen pronotalis, or Neotibicen tibicen are possibilities. If you took the photo in 2011, Brood XIX could also be possible. It could also be one of the many species that we don't have an article on. I'd look for confirmation within the first three, however. Ian.thomson (talk) 04:38, 13 July 2015 (UTC)

Thanks, I took the photo yesterday after my daughter found it on the porch. These were taken out there. I brought it in so I can take better close-up photos, but if someone is going to delete them, what's the use? I need to have some article where they can go. Bubba73 ^{You talkin' to me?} 04:44, 13 July 2015 (UTC)

• Neotibicen auletes - no photos
• Neotibicen pronotalis - can't really tell
• Neotibicen tibicen - can't really tell

Also, away from the coast, they like to shed their shell on pine trees, if that is a clue. And I'm pretty sure they are out every year. Bubba73 ^{You talkin' to me?} 04:47, 13 July 2015 (UTC)

Is it safe to put these photos in Neotibicen? Bubba73 ^{You talkin' to me?} 23:20, 13 July 2015 (UTC)

I'd try it. Worst that happens is it gets removed again. Those look like the kind we get here in SC, and Neotibicen is widespread. Ian.thomson (talk) 01:58, 14 July 2015 (UTC)

OK, I've done that. But I'm hoping to take better photos and have them stand. Bubba73 ^{You talkin' to me?} 02:16, 14 July 2015 (UTC)

Scarce pictures of Pluto from New Horizons

NASA's New Horizons probe has done well to make its journey to Pluto. But the pictures posted have been few and far between. Why is it so long between posted photos? I would have expected at least one per day. Following the closest approach in the coming week, when does NASA plan to post at least one high resolution photo? Decades ago, when they first crashed a probe into the moon (Ranger)and when they first landed an unmanned probe on the moon (Surveyor), I recall a much more satisfying display of photos soon thereafter. They used the term "Quick and dirty" for the release of a few photos, rather than waiting for the inevitable tweaking and perfecting of the images. I've searched the NASA site without finding a good explanation fro their stinginess in posting photos.The low baud rate seems an inadequate explanation. Equipment sometimes fails unexpectedly, so programming in a quick image grab would seem to make sense. Edison (talk) 03:13, 13 July 2015 (UTC)

The data transmission rate is slow, it will take 16 months for all the collected data to be transmitted to the earth. [15] μηδείς (talk) 03:49, 13 July 2015 (UTC)

That is in no way an explanation. You don't have to wait for the last datum to be received to release the first image. People got annoyed with the Dead Sea Scrolls researchers for waiting decades before releasing images, and in that case, someone was able to circumvent them and release the closely held information. At the stated baud rate, how long would it take to transmit one image? Minutes? Hours? What was the timing of the release of the last few images seen so far? Are there more than the ones from 9 July at 5.4 million km and July 11 at 4 million km which I could find at NASA and Wikipedia? It is now less than 1,200,000 km from Pluto. Edison (talk) 03:55, 13 July 2015 (UTC)

Wow, please call NASA and notify them of your personal displeasure. You've gotten the proper answer, regaling us with straw men objections and conspiracy theories serves no purpose. μηδείς (talk) 18:11, 13 July 2015 (UTC)

As I write this, five very large dishes at the Goldstone Observatory, part of the Deep Space Network, are simultaneously aimed at New Horizons. You can monitor their progress: DSN Now. You can read about communications: JHUAPL's New Horizons spacecraft communications website. Right now, the total downlink is about two kilobits per second. Goldstone is the best-equipped station on Earth for communicating with the New Horizons probe. In a few hours, as Earth rotates, California will no longer be able to see Pluto, and the data downlink speed will decrease. Eventually, the link will be reestablished with the next DSN station (in Spain, and then in Australia later).

Of the few kilobits of data, only a tiny fraction is available for scientific data product. Most of the link bandwidth is used for operational spacecraft telemetry and control. It really, really actually will take days or weeks for high-quality scientific image data to download back to Earth.

Need something to keep yourself occupied? Keck Observatory kicked off its free online Cosmic Summer School yesterday. Here's Week One of a twelve week educational program: Administrator Bolden discussing NASA's long term mission objectives. Around the time this twelve-week summer school completes, New Horizons is scheduled to begin (yes, to begin) downlinking science product. It might be a good time to exercise some patience and acquaint yourself with the realities of space travel!

Nimur (talk) 04:28, 13 July 2015 (UTC)

The downlink schedule is here: [16]. Rmhermen (talk) 04:24, 13 July 2015 (UTC)

Thanks to all. Such novel info from a little- known ?planet. One can hardly wait, and I hope nothing breaks down in the months we have to wait for the big download.. When the "Instant of closest approach" occurs, and the time for lightspeed transmission from Pluto has passed, I only hope that some kewl image will be displayed for all to see. Edison (talk) 04:40, 13 July 2015 (UTC)

According to this morning's press release, the first data will be a status signal that arrives around 9 PM (EDT) on Tuesday evening. You can watch the conference live now on http://www.nasa.gov and it will probably be archived for later viewing. There is a very neat 3D animation of the instrument command sequence to aim the various instruments at their targets during the flyby. Nimur (talk) 14:49, 13 July 2015 (UTC)

And here is the best image we'll get until after the flyby. -- ToE 11:28, 14 July 2015 (UTC)

And here it is in full resolution. Now we wait. -- ToE 14:16, 14 July 2015 (UTC)

Watch your superlatives! The image you linked is not "the best" one we have! If you're really concerned about image quality, avoid consumer-grade republishing services like Amazon Web Service and "Instagram" - these services destroy images with crummy recompression quality to reduce image size! This spells disaster for scientific image processing. Personally, I find it shameful and insulting that these web companies would apply such poor-quality lossy compression to image files. Their image-corruption is regrettable when it destroys the quality of normal personal photographs. But to apply such a poor-quality compression after so many billions of dollars, billions of miles, and thousands of seconds to losslessly transfer these bits of data from the far side of our solar system - this is tragic! Are these companies so overwhelmed by the bandwidth and technical difficulties and costs that they can't transfer data from one air-conditioned data center to another over a wire?

If you want the best images available from the New Horizons mission, view the original images from NASA's New Horizons image gallery, and use the planetary science database to retrieve research-grade scientific data products (including uncompressed images):

• Small Bodies Node at the Planetary Data System, where Pluto scientific data resides
• New Horizons Jupiter Encounter database (a branch of NASA's PDS database hosted at New Mexico State University)
• NASA's Three-Billion-Mile Journey to Pluto Reaches Historic Encounter, the press release associated with the specific LORRI full-frame image posted above; and the full resolution image hosted at NASA.

Even these data may be compressed or reprocessed; you have to read the details in the data release information to be sure. Each time the data is re-compressed by third parties, more information is lost; so the closer you get to the source, the better the image is for scientific purposes.

Nimur (talk) 14:38, 14 July 2015 (UTC)

Actually the AWS image is PNG not lossy compression. What the source was, or whether it was ever compressed losily internally in Amazon, I have no idea. It is also 1024x1024, and I wonder if it was uploaded like that to Amazon, or reduced to that resolution internally by Amazon. Nil Einne (talk) 21:32, 15 July 2015 (UTC)

One other point that hasn't been mentioned yet - New Horizons can't broadcast and take photos at the same time. The camera is fixed, so the spacecraft needs to rotate in order to point it at an object - and that means the antenna goes out of alignment with Earth. To avoid anything interesting being missed as it approaches the Pluto system, the New Horizons probe is currently being steered to prioritise data capture over transmission, and most of the images are still stored in the spacecraft's memory. Once it's in a less interesting bit of space, it'll be pointed back at Earth and send back all the saved data. (In case you're wondering why they have such a cumbersome way of doing things - most spacecraft do have a steerable camera, but the steering systems are heavy and can break down easily. For the very long mission to Pluto, they decided to go with the lower risk system and save a bit of weight). Smurrayinchester 10:40, 14 July 2015 (UTC)

• And while you wait, you can read up more about the transmission speed limitations and the methods employed to overcome it: Talking to Pluto is hard! Why it takes so long to get data back from New Horizons. Or, read about the state-of-the-art communication codes used, which come remarkably close to the Shannon limit. Abecedare (talk) 15:13, 14 July 2015 (UTC)

Annual average sunshine vs total horizontal irradiation

Why do these two maps[17][18] look so different? I realize that they measure different things, one is annual average sunshine, and one is total horizontal irradiation, but I would have expected them to be correlated to each other, especially when averaged over long periods of time (29 years in the first one, one year in the second one). My other car is a cadr (talk) 04:54, 13 July 2015 (UTC)

One is measuring hours of sun, the other is measuring the total insolation energy. Basically the SW sees the sun less often than the SE, but it is brighter when it does come out. Also, you do actually get some insolation even when it is overcast. Greglocock (talk) 08:19, 13 July 2015 (UTC)

And part of the reason for the difference is that the East of England has far less rain and cloud, and therefore sees the sun more often, and another part of the reason is the the SW of England is quite a lot further South than the SE, and therefore gets a high irradiance when the sun does shine.--Phil Holmes (talk) 08:49, 13 July 2015 (UTC)

No, sorry. The latitude difference is not enough to be very significant; sun is always the same brightness (plus or minus about 3% depending on how far away it is at that time of year), so it doesn't make sense to say "it's brighter when it does come out". However, what does vary is how high it is at different times. Any particular horizontal area gets about 2.5 times as much sunlight when the sun is 60° above the horizon as it does when it's only 20° above (because sin 60° / sin 20° is about 2.5). This is why the summer sun warms you more than the winter sun. So the pattern would be explained if the southwest of England tends to be sunnier in May-June-July whereas the southeast is sunnier at other times of year. Whether that's true or not, I don't know. --174.88.133.35 (talk) 09:07, 13 July 2015 (UTC)

" it doesn't make sense to say "it's brighter when it does come out". " is nonsense I'm afraid. Speaking as an ex solar car strategist I can assure you that just because the sun is out at a particular latitude at a particular solar time, the insolation can vary by +/-30% depending on high altitude cloud, dust, and cloud albedo. If you don't believe me then it is no skin off my nose, check out my graphs of actual data on the WSC page. Greglocock (talk) 09:28, 13 July 2015 (UTC)

• Fair point. I considered that if there was significant reduction for that sort of reason then it would not be considered "out", but I can't force that interpretation on the Met Office. --174.88.133.35 (talk) 04:45, 14 July 2015 (UTC)

Cool, here's the 'official' definition of bright sunshine - 120 W/m^2, ie 1/8 of typical australian summer sun at noon!

http://www.metoffice.gov.uk/hadobs/msg_sunshine/ejgood_sunshine_paper_final.pdf Greglocock (talk) 01:23, 15 July 2015 (UTC)

Thanks, y'all. My other car is a cadr (talk) 10:28, 13 July 2015 (UTC)

Resolved

And surely horizontal irradiation is given by maximum solar irradiation times the sine of the sun's elevation. Further South (until you reach the tropic of Cancer) = higher solar elevation = higher horizontal irradiation.--Phil Holmes (talk) 14:41, 13 July 2015 (UTC)

Military device

In this video, what's the device at 2:47? I think that's some kind of device for setting the fuzes on the cannon shells -- did I guess well? 2601:646:8E01:9089:F5D3:BBA6:DE14:1A84 (talk) 09:19, 13 July 2015 (UTC)

It's called an "automatic fuse setter" (in English) and was linked to an analogue computer called a "predictor". This calculated the speed and direction of the aircraft, which way the wind was blowing and how long it would take to get the shell into the gun, fire it and then fly towards the target. They were developed independently in the UK and Germany during the 1930s. The predictor used by the Germans was called the Funkmessegerate. [19] Alansplodge (talk) 12:36, 13 July 2015 (UTC)

I think it is a device for setting the fuze on anti-aircraft shells, the kind that burst in mid-air, also known as flak. If the shells are to burst close to enemy aircraft flying overhead the fuze must be set to detonate at the correct time after firing. This device would seem to allow the fuze timing to be set just a few seconds before the shell is fired, giving gunners the best chance of causing damage to the enemy aircraft. Dolphin (t) 14:14, 13 July 2015 (UTC)

That's kind of what I said above; apologies if it was unintelligible. There's a brief mention of automatic fuse setters at Artillery fuze#Fuze setting. Alansplodge (talk) 16:54, 13 July 2015 (UTC)

Thanks, all! 2601:646:8E01:9089:F88D:DE34:7772:8E5B (talk) 04:38, 14 July 2015 (UTC)

False 'controversy'

Wondering why there exist pages named Dental amalgam controversy and Thiomersal controversy when there is no scientific- or respectable public- controversy regarding these topics. We know there is no genuine controversy, and the reliable sources prove this. Is this an active failure to moderate these topics, or have they just not been addressed lately? Nevard (talk) 10:12, 13 July 2015 (UTC)

It's quite possible that the situation is based on scientific bullshit, public misinformation, self-aggrandizing media figures, and disreputable others. But that doesn't matter from a WP:GNG standpoint for the topic to merit a page. In each article it's cited that there is a concern, and it's cited and made clear that it's completely unscientific and not currently based on anything respectable. It's not a "controversy" in that there are two reasonably meritorious sides debating some topic using sane logic, facts, etc. But it does meet the what controversy says, in that it's a long-running public dispute of opinion and point of view. DMacks (talk) 12:53, 13 July 2015 (UTC)

The fact that there is no controversy among mainstream scientists does not mean that there is no controversy. As DMacks says, there is a long-running public dispute. The existence of the controversy is notable and should be reported, as well as the fact that there is agreement among mainstream scientists. Robert McClenon (talk) 20:30, 13 July 2015 (UTC)

Also, Wikipedia still has articles about complete bullshit. The existence of the article merely means that the bullshit really exists (even if it exists as bullshit) and not that Wikipedia holds that the bullshit should be seen as plausible or likely. Just that it's real, documented bullshit. There's a thousand articles on other kinds of bullshit, and Wikipedia cannot merely ignore notable bullshit, merely because it is bullshit. Wikipedia needs to adhere to WP:NPOV, which means, among other things, not pretending that bullshit is not bullshit, but it doesn't mean we pretend the bullshit doesn't exist in the first place. --Jayron32 00:06, 14 July 2015 (UTC)

Wikipedia also has bullshit. InedibleHulk (talk) 01:33, July 14, 2015 (UTC)

For the same reason we have an article on Galileo being convicted of heresy for claiming the Sun was at the center of the solar system. It's not there because there is real scientific controversy over the topic, but because it was a notable event that had an effect on society. In the case of thiomersal, that's significant for lowering the inoculation rate, thus leading to disease outbreaks. StuRat (talk) 13:08, 13 July 2015 (UTC)

That is different. There was real scientific controversy at the time. Galileo had not proved that the Sun was the center of the solar system. He had only made discoveries that strengthened the heliocentric view, but did not disprove the geocentric view. The heliocentric theory only became generally accepted when Isaac Newton's theory of universal gravitation provided an explanation of what the force was that kept the planets in their orbits. If Galileo said that he had proved the heliocentric theory, then he was mistaken. Robert McClenon (talk) 20:30, 13 July 2015 (UTC)

I believe the situation with vaccines was very similar. There was a study which purported to show a link between vaccinations and autism [20], with mercury in the thiomersol vaccines being the prime suspect. So, there was a genuine scientific controversy at the time. Later that study was discredited, and many other studies have shown no link, so there is no longer a scientific controversy now. StuRat (talk) 22:10, 13 July 2015 (UTC)

It's pretty simple: Wiktionary defines "controversy" as "A debate, discussion of opposing opinions; strife.". Notice that the words "truth", "science" and "reasonable" don't enter into that definition. Hence there can be controversy even when it's completely and firmly established that one side are spouting primo bullshit and are flat out utterly, UTTERLY, stupidly wrong. (eg. There is an Apollo moon landing controversy...even though there is absolutely zero evidence that it didn't happen - and a gigantic mountain of evidence that it did.)

These articles are about the controversy itself - not the underlying facts. So we must ask ourselves:

1. Is it true that there are people debating this thing?
2. Is that debate notable?

Our gold standard for both truth and notability in Wikipedia is the existence of 3rd party reports about the subject in "reliable" sources. In this case, we're not looking for reports about the truth about the issues surrounding dental amalgams. We're looking for reports that prove that people disagree about this subject and are debating it.

There are indeed reliable sources that say that some people find these things controversial...and there are enough of them to establish notability. Note that by creating these articles, we're not saying that the people on both sides of the debate are equally correct - we're merely saying that some people are de bating it...which they undoubtedly are.

SteveBaker (talk) 22:01, 13 July 2015 (UTC)

It's the difference between significance and notability. We have an article on intelligent design, but we don't mention it in the article on evolution. The former is not significant with respect to the latter. It may not deserve respect as a scientific theory, but it deserves an entry in an encyclopedia. Documenting something is of course not the same thing as endorsing it. Someguy1221 (talk) 01:41, 14 July 2015 (UTC)

Why do men find fat women attractive?

Does fat fetishism have any evolutionary basis, that is to say does it provide an advantage to passing on genes? Obviously healthy women are more fertile than underweight women, and would be better mothers. However, severely obese women are likely to die early before the child is an adult and thus are not good mothers. 39.176.130.234 (talk) 23:06, 13 July 2015 (UTC)

De gustibus non est disputandum. Also, human behavior is not deterministic to the level of infinite mathematical precision and is subject to notions such as free will and personal preference. There does not need to be a deterministic evolutionary, "all humans must do X because they are forced to by the magic God named "evolution!" explanation for individual personal choices and preferences, such as foods you like, people you are sexually attracted to, and music one listens to. Not every matter of individual human behavior which is different than your personal preference is so aberrant as to need to be proven to be wrong because "evolution" says it is. Sometimes, people are different, and it isn't an "evolutionary disadvantage", which you are using here as code for "It feels wrong to me". --Jayron32 00:04, 14 July 2015 (UTC)

Jayron, I certainly agree that not all personal preference needs to be explained by evolutionary psychology. But your assumption that the OP is speaking in "code" is frankly out of line. There's not a shred of evidence for it in the post, and you owe the OP an apology. --Trovatore (talk) 08:44, 14 July 2015 (UTC)

• In an area where famine was common, an obese wife would be more likely to survive one, and still be able to bear and nurse children, than a normal weight woman. Also note that obesity isn't very likely to kill a woman before menopause, and in a society with strong social supports, others would raise her children when she did die.

• That fat women were desired in prehistoric times is implied by Venus figurines.

• Also note that, in a society where obesity is the norm, having a normal weight may be a sign of sickness. StuRat (talk) 00:11, 14 July 2015 (UTC)

Also not "normal" weight there. InedibleHulk (talk) 01:28, July 14, 2015 (UTC)

In parts of the world obesity is considered extremely attractive in a woman as a sign of prosperity (see leblouh). For a long time deformed feet were considered attractive in China. Both of these things are considered turn-offs amongst most men in the modern world. There is substantial research on sexual attractiveness, but it is basically impossible in a realistic study to fully separate social from genetic factors in what we find attractive. Maybe men are inclined to pursue women they see as best able to provide and raise healthy children, or maybe they are inclined to pursue whatever standard society holds at the time, or perhaps they are inclined to pursue whatever is in fashion amongst the wealthy (see for instance this article on the transition from pale skin to tan skin being considered attractive). And of course, there are massive and largely inexplicable variations in preferences within any population. Are these differences driven by social or genetic factors? Again, nearly impossible to tell. But it certainly seems like it's far more complicated than simply which female seems the healthiest. I think a firmer hypothesis than "men are inclined to pursue the most child-ready women" would be "men are inclined to pursue whatever qualities they associate with prosperity, muddied by inexplicable variability." Someguy1221 (talk) 00:34, 14 July 2015 (UTC)

These are all good answers, I think Jayrons answer in particular should not be dismissed. There is a very real tenancy to explain things in "evolutionary" terms like the above, however a distinction has to be drawn between a post hoc rationalization and an actual causative relationship. It's not hard to explain ANYTHING this way: why do some find fat women attractive, why to some find thin women attractive, why to some find in between women attractive? We can find compelling answers to ALL of those, but if you can explain ALL observation with one "hypothesis" then you haven't really explained ANY, it becomes unfalsifiable. Vespine (talk) 02:42, 14 July 2015 (UTC)

Not all sexual preferences can be given an evolutionary explanation. Necrophilia, for example, doesn't seem to be a likely method to pass on one's genes (except perhaps where the male is dead but still has viable sperm). So, that would make it more likely as a brain malfunction. StuRat (talk) 20:22, 14 July 2015 (UTC)

And the reference is superstimulus.. Actually, it just occurred to me, watch Dan Dennett's TED talk called "Cute, sexy, sweet, funny", I don't want to google that phrase at work to link it, you'll have to look it up yourself ;) He discusses precisely this subject. Vespine (talk) 02:46, 14 July 2015 (UTC)

Googling "more cushion for the pushin'" also probably isn't safe for work, but as dumb as that saying is, pelvis-on-pelvis grinding probably really wouldn't have been so great for the species, if we were all down for that. There's something to be said for pillows in bed, especially if you need to hunt mammoth the next morning.

That only applies to liking big butts and thighs. Big stomachs and jowels, the other brothers can deny. InedibleHulk (talk) 02:59, July 14, 2015 (UTC)

Westerners moral crisis, I've just read someone making a culture-relativist argument that they aren't necessarily, on Youtube. In this moral landscape, how can there be a consensus on what's attractive? Asmrulz (talk) 05:19, 14 July 2015 (UTC)

I've heard it described as "more cushion for the pushin'." ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:20, 14 July 2015 (UTC)

Some girls try it 'n' go on a diet Then they worry 'cause they's too fat Who wants t'ride on an ironin' board? That ain't no fun ... I tried me one Grow that meat all over yer bones Work the wall with the local Jones 'N' while you do it, remember this line The Sniffer says it all the time "THE BIGGER THE CUSHION, THE BETTER THE PUSHIN etc." Frank Zappa "Sex" Contact Basemetal here 08:19, 14 July 2015 (UTC)

"Fat Bottomed Girls... make the rocking world go round". SemanticMantis (talk) 14:27, 14 July 2015 (UTC)

The question is not why men find fat women attractive. If a woman is able to bear able children, some men will find her attractive. We would need to explain wy men find sometimes attractive women that cannot bear children. --Yppieyei (talk) 14:44, 15 July 2015 (UTC)

Not everyone is hung up on reproduction. Some would even consider it an advantage if she cannot reproduce. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:43, 15 July 2015 (UTC)

If you're a male and you're attracted to females that can't reproduce you will have a little trouble passing on that feature to your offspring because you won't have any. If that preference is connected to a gene then that gene will be eliminated from the gene pool pretty fast. Contact Basemetal here 18:18, 15 July 2015 (UTC)

And if you don't want children, you won't care about the gene pool. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:24, 15 July 2015 (UTC)

Mr. basemetal just because something exists does not mean that it has a "survival factor" many things (like wanting a female who can't reproduce) is not based on a survival factor it is a BY-PRODUCT of other survival factors. Void burn (talk) 18:28, 15 July 2015 (UTC)

I think major obesity and big bellies of cellulite is extremely unattractive. But unless her calves are thick as average thighs and she has over two chins the right length skirt would make me horny as long as she stays clothed. (I would find out in 3 seconds whether blubber-y feeling women aren't for me: If I could get through the first few seconds of cuddling without being disgusted they would be very fun until I saw her eat, if I couldn't then they'd all disgust me). Whatever ancient genes caused this, I don't know. Sagittarian Milky Way (talk) 03:19, 17 July 2015 (UTC)

Check this out. (May or may not be safe for work, depending on where you work.) Ask yourself this: Too big? Too small? Just right? Everyone will have a personalized answer. ←Baseball Bugs ^{What's up, Doc?} carrots→ 07:08, 17 July 2015 (UTC)

July 14

Penis in vagina

Why is "penis in vagina" sex so ubiquitous in nature compared to fertilizing eggs externally or other methods of non-preventative procreation?

Cause it's a lot more fun. Contact Basemetal here 17:31, 14 July 2015 (UTC)

That reply is of course completely and utterly backwards. It is 'fun' because if it wasn't, animals wouldn't engage in it, and would thus fail to reproduce. AndyTheGrump (talk) 17:39, 14 July 2015 (UTC)

And of course many animals don't need to do anything of the sort. Penis-in-vagina sex is in no way necessary for a viable population, as demonstrated by my many refs below. SemanticMantis (talk) 18:59, 14 July 2015 (UTC)

There is obviously a benefit to letting a baby grow in the womb for a while instead of laying an egg. So, in that case, how else do you expect the egg to be fertilized? 209.149.113.136 (talk) 17:38, 14 July 2015 (UTC)

As noted below, the male can just hand the female a sperm packet (an entirely different way to deliver one's package). StuRat (talk) 20:11, 14 July 2015 (UTC)

You're really missing out on the wide wide world of sex! In fact, the way humans procreate not the norm. First let's get plants out of the way - pollination uses no penis nor vagina, and often involves a second species pollinator as an intermediary.

For animals - did you know that squid use a special arm called a Hectocotylus to inseminate females? And then there's many things that use Spermatophores - a salamander puts a little sac of sperm down, then does a mating display, and if the female likes it, she'll take it in to her body. Of course most bony fish use external fertilization, as do many amphibians, corals, protozoans, etc.

The Bdelloid rotifer has some of the weirdest "sex" - they have no males, only females, and they can incorporate DNA of their dead sisters when rejuvenating after dessication! Discover magazine couldn't resist a little anthropomorphic language, and called them Lesbian Necrophiliacs [21]

Then there's the bedbugs and other invertebrates that use traumatic insemination - the females don't have anything like a vagina, and a male just sort of stabs in to the abdominal cavity. And while we're on the topic of insect genitals, they don't have penises, they have Aedeagus, which is a rather different thing altogether.

Every male hymenopteran is born from an unfertilized egg! That's part of the fun of haplodiploidy.

The Amazon_molly reproduces solely through gynogenesis - a male (of a different species) is required, but his sperm do nothing! Then there's the very common Parthogenesis, which leads to things like many female aphids being born pregnant with another female - no sex required.

There are many other strange tales of sex and nonsexual reproduction in the living world, but hopefully this gives you a better feel for the variety of things out there that can get the job done just fine. While there are many benefits to internal fertilization and live birth that result from penis in vagina copulation, that form is not the norm, neither by number of species nor by number of practitioners. SemanticMantis (talk) 18:57, 14 July 2015 (UTC)

It might be the most common, if you look at total biomass of animals that engage in internal fertilization (since that would be "heavily weighted" towards larger animals) versus other forms of sexual reproduction (since that leaves out most microbes). StuRat (talk) 20:10, 14 July 2015 (UTC)

Nope. Good thing to think about, but terrestrial insects have more biomass than terrestrial vertebrates, and they don't have penises. Just ants alone have about the same biomass as humans do. And that's not even mentioning huge amounts of bony fish and marine invertebrates, compared to the very few marine animals that practice internal fertilization. Biomass_(ecology)#Global_biomass has some info, but could use some expansion. I'll buy that PIV copulation is the most common method of fertilization among terrestrial vertebrates (by species number, individual number, biomass, etc), but that's about it. SemanticMantis (talk) 20:36, 14 July 2015 (UTC)

More variety that I should mention - most birds don't have anything like a mammal penis - see Pseudo-penis and cloaca. Spiders use another type of specialized "arm" for insemination - the Pedipalp. SemanticMantis (talk) 21:25, 14 July 2015 (UTC)

MAF sensor disconnection

Most cars (for some time now) are equipped with a mass air flow sensor I know some cars have a MAP sensor but my question is only in regards to vehicles with MAF sensors. Some vehicles will still run with the MAF sensor disconnected while others will not run at all with the MAF sensor disconnected. Why is this? Void burn (talk) 13:57, 14 July 2015 (UTC)

The MAF is used to tell the computer how much air is coming in. If it is disconnected, the computer gets no signal. So, the computer could be programmed to assume "average" air flow and then send an "average" amount of gas to the engine. Or, the computer could be programmed to assume "no" air flow and then send "no" gas to the engine. It is really up to the engineers to decide what to do when the MAF sensor isn't sensing anything. 209.149.113.136 (talk) 15:35, 14 July 2015 (UTC)

I would imagine that it would be better engineering to program the computer to assume "average" Stoichiometry so that in the event the MAF sensor stops working the vehicle will still drive until the MAF can be repaired. Seems like this should be an industry standard if reliability is desired. Void burn (talk) 17:16, 14 July 2015 (UTC)

In the interests of robustness the engine will attempt to estimate the MAF from the throttle plate angle and the rpm, if the MAF sensor fails. Greglocock (talk) 01:05, 15 July 2015 (UTC)

How can you determine the percentage some feature is determined genetically?

What scientific methods besides comparing twins are useful to tell the percentage that genes plays in a feature? For example, what's the % of our height, intelligence, that's genetically determined. Or how do genes increase the chances we develop some illness like Parkinson or Alzheimer's.--Scicurious (talk) 23:12, 14 July 2015 (UTC)

You're right that twin studies are an important tool. Other than that see Disease_gene_identification - now heavily influenced by genomics. There's some info and refs at Nature_versus_nurture#Advanced_techniques, but it's not a very good section. Make sure you read the section on IQ in that article and we have a whole article on Heritability of IQ. Lots of work is also done with model organisms - Knockout_mouse is a very common and popular tool. SemanticMantis (talk) 00:29, 15 July 2015 (UTC)

Those are some general methods; for your specific questions, see Parkinson's_disease#Genetics and Parkinson's_disease#Genetics. The "percent influence" of genetics is hard to quantify, and my understanding is that each research project will operationalize that concept for each specific question, but there are some general approaches discussed at Heritability#Estimating_heritability. The claims in those disease articles both have refs to the academic literature, if you don't have access you can often find reprints by googling the title, or you can ask for a copy through WP:REX. You may also be interested in List_of_genetic_disorders. SemanticMantis (talk) 00:39, 15 July 2015 (UTC)

You must have an inherited tendency to repeat Parkinson's_disease#Genetics. :-) StuRat (talk) 00:46, 15 July 2015 (UTC)

Right, Alzheimer's_disease#Genetics. SemanticMantis (talk) 01:02, 15 July 2015 (UTC)

Some evidence can be gleaned by looking at two large and genetically similar populations in different environments. For example, comparing cancer statistics within China to cancer statistics amongst Chinese immigrants to the United States, as was done in this study. It's conceptually similar to a large-scale twin study. Someguy1221 (talk) 02:56, 15 July 2015 (UTC)

"For example, what's the % of our height, intelligence, that's genetically determined." Is it true that the characteristics of genes (or the characteristics that give rise from genes) are largely determined by environmental variables? Void burn (talk) 17:16, 15 July 2015 (UTC)

The phrase "explained by" is sometimes seen in popular literature that presents statistical arguments. I view such vagueness with great suspicion. One of the meanings it might have is discussed in Cross Validated. Jim.henderson (talk) 17:55, 15 July 2015 (UTC)

Oh. We do have an article "Explained variation" with appropriate criticism. Jim.henderson (talk) 18:00, 15 July 2015 (UTC)

July 15

bainbridge reflex

wanna know about bainbridge reflex05:52, 15 July 2015 (UTC) — Preceding unsigned comment added by 36.252.1.148 (talk)

Have you tried Bainbridge reflex? Richard Avery (talk) 06:14, 15 July 2015 (UTC)

Mononucleosis

Is kissing the only way mononucleosis is transmitted? 90.192.122.101 (talk) 07:34, 15 July 2015 (UTC)

And sexual intercourse. As the article says, "A person becomes infected with this virus by direct contact with infected body fluids", including saliva, urine, blood, and tears, so any licking and spitting would do it, and sharing food etc.--Shantavira|^{feed me} 08:01, 15 July 2015 (UTC)

then why isn't it more common if it can be pretty much transmitted through all of those? That's almost daily human contact. Surely everyone should get it then. 90.192.122.101 (talk) 09:04, 15 July 2015 (UTC)

Our article says, "About 95% of the population has been exposed to this virus by the age of 40, but only 15–20% of teenagers and about 40% of exposed adults actually become infected." You're correct that almost everyone gets it eventually. The terminology can be a little confusing. Let me try to summarize. Mononucleosis has multiple causes, but the overwhelming majority of cases are caused by the Epstein–Barr virus. However, only a minority of people who contract the virus will develop mononucleosis. In the majority of people it causes no or only minor symptoms. Epstein–Barr is a member of the Herpesviridae, which also includes among other viruses the chicken pox virus and the viruses that cause herpes simplex (usually simply called "herpes"). The Herpesviridae are adapted to evade the immune system and establish a latent infection that persists for the rest of your life, essentially "hiding" inside some of your cells. The viruses sometimes simply lay dormant indefinitely, but they can become reactivated and cause a new outbreak. Herpes is well known for repeated cycles of active and latent infection, and reactivation of the dormant varicella (chicken pox) virus in previously infected persons is what causes herpes zoster, commonly known as shingles. Because they usually persist indefinitely in infected hosts, cause relatively limited symptoms, and are easily transmitted, many of the Herpesviridae are near-universal in the adult human population. This ties into what's called optimal virulence; pathogens tend to become less damaging to their hosts over time. Pathogens want to reproduce, and relatively healthy hosts can spread them better than really sick or dead ones. These viruses are quite evolutionarily successful! As a personal demonstration, I am cytomegalovirus positive, but I've never had anything worse than a typical cold, so I probably had an asymptomatic infection. The only reason I know I'm infected with the virus is because I donate blood, and all donors are tested for the virus, because CMV positive blood can't be given to pregnant women, newborns, or immunocompromised people. Anyway, I hope that was informative! If you liked my explanation, I have one request: donate blood regularly if possible! It saves lives! Thank you. --108.38.204.15 (talk) 12:26, 15 July 2015 (UTC)

Look at virulence and optimal virulence. Diseases do best the longer their hosts live and the better those hosts spread their germs to others. New pathogens like HIV usually spread at first because they are highly communicable. But if they cause quick morbidity and death, they don't pass on to as many hosts as possible. Over time, strains that stress the host the least tend to become the most common (although their are other factors involved which can counteract this). Many viruses like herpes viruses ("everyone has herpes") become widespread but cause fewer obvious symptoms. For example, my mother gets cold sores, but none of the rest of us in my immediate family do. I got shingles while in the hospital, but the case was so mild I thought I had a mosquito bite. Of my clique at college, only one of us "got" mono (i.e., symptoms), and that led to hospitalization for jaundice, but none of the rest of us did, although there was some intimate contact within the group. As long as a disease has any easy time of spreading (promiscuity, large classrooms) it will tend to become less and less symptomatic while it becomes ever more prevalent. μηδείς (talk) 21:13, 15 July 2015 (UTC)

Saved shark? Looked pretty dead to me.

There've been some reports (for example here) of a stranded juvenile great white that was supposedly "saved" yesterday in Cape Cod. In the footage that I've seen it looked utterly dead and I have not seen any footage showing it swimming away. Does it look like websites just repeated the story without checking it? How do they know it was saved? Does anyone here have any source that can prove it swam away? Is it at all credible that a shark that was beached for hours can survive the ordeal? Contact Basemetal here 14:28, 15 July 2015 (UTC)

Did you not see it move its mouth and tail at ~5 seconds, and everybody cheers? Later, in the water, a guy says something like "see the gills pumping"? and if you look closely you can see that too. The shark certainly doesn't look dead to me in that video, though I admit it's not clear or certain that it will still be alive next week (I guess that goes for all of us ;) For further video evidence, see here [22] - the second video shows the shark clearly swimming under its own power - apparently they dragged it about a mile out. Probably took a while to recover from the shock and get more oxygen in to its blood. SemanticMantis (talk) 14:47, 15 July 2015 (UTC)

I did see it move at the beginning but then by the time they towed it into the water it looked pretty dead. But you're probably right. Here's another video. It seems to show footage of the shark finally moving in the water and it confirms that it took a long time to bring it back. Now as to my more general question: How long can a shark stay out of the water and still remain capable of being brought back? Incidentally this reminds me of a scene (having to do not with a shark but an octopus) in the Japanese movie Departures (about 18 m 30 s into the movie) where the woman (Ryōko Hirosue) brings home an octopus for dinner. But then suddenly the octopus starts moving on the kitchen floor. The couple (husband played by Masahiro Motoki) rush to release it in Tokyo harbor but the guy's already dead. How long can you keep an octopus out of the water before it dies for good? Contact Basemetal here 18:06, 15 July 2015 (UTC)

See here [23] for a discussion of the octopods. Several people are reporting survival out of water times on the scale of hours. Given that many of them have a natural behavior of moving over land between tide pools, it's not so surprising that they can survive out of water for a while, especially if kept moist. SemanticMantis (talk) 18:43, 15 July 2015 (UTC)

Maybe this will turn out to be like the lion and the mouse, and the shark will refrain from munching on swimmers. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:01, 15 July 2015 (UTC)

Yeah right I wouldn't count on it. Now if you wanna get in the water, be my guest A shark's brain is pretty small. They're superefficient killing machines but I doubt they can remember anything. Killer whales would be better candidates, but they don't munch on swimmers to begin with. At least there's no recorded case in the wild and what happened in Florida a few years back was clearly an accident. (In fact the guy didn't munch on anything but it did drown its trainer) Contact Basemetal here 18:06, 15 July 2015 (UTC)

"At least there's no recorded case in the wild" - in other words, they make sure not to leave any witnesses. Iapetus (talk) 10:45, 16 July 2015 (UTC)

Without getting into the realm of legal advice, it's still interesting to imagine that if someone is attacked by a shark, and it could be proven to be the one that was put back in the ocean, whether those who did so could be held liable for the attack. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:27, 15 July 2015 (UTC)

There should be a big "if" attached to the "it could be proven". I'm not sure anyone took a DNA sample that would stack up in court, nor did anyone attach a tracker. It's possible there are sufficient high resolution photos showing the dorsal fin or other unique markings, and despite these being from a juvenile [24] [25] they could be used to uniquely identify the shark later (bearing in mind the standards acceptable for tracking are likely to be different from that for a court case) but this seems unlikely. Noting you'll also need to be able to use the same method for the attacking shark. Nil Einne (talk) 02:55, 16 July 2015 (UTC)

If you tie a rope around a shark's tail, and drag it into the ocean with a boat as these people did, how then do you get the rope off the tail?Edison (talk) 03:13, 16 July 2015 (UTC)

Using hands? Maybe a knife or safety scissors. I can't tell from the video how they tied it on, but I'd probably use some sort of quick release knot, perhaps some variant of the Highwayman's_hitch [26] or some other slipped knot. SemanticMantis (talk) 14:20, 16 July 2015 (UTC)

From comments I've seen the bystanders could have dragged it into the water with their bare hands (assuming they had the physical strength to do it) with no danger to themselves as the shark in the position it was beached in couldn't hurt them (unless they were foolish enough to go stick their hands in its mouth) but that alone would have been pretty pointless as the real hard thing was to induce it to start breathing again, to restart its gills. Apparently, even in the water, if a shark doesn't keep moving, it suffocates. Other species of fish have the ability to breathe while staying put but not sharks. So, after they had dragged it into the water, the shark had to be towed alongside the boat to revive it and that took some time. In any case you couldn't do that by dragging it from its tail. They had to tie a rope around its trunk or whatever that part of the body is called. I suppose that makes the problem of getting back your rope a little easier to solve, if that's what you're worried about. Contact Basemetal here 15:41, 16 July 2015 (UTC)

July 16

What's the name of this rock formation

Please, what's the name of this kind of rock formation ?

= the “teepee fountain” in Thermopolis, WY

As far as I understand, it works almost like a stalagmite/tite, but water/sediments come from the inside, no ?! Thanks in advance. Blump007 (talk) 04:35, 16 July 2015 (UTC)

It's called a flowstone. --Jayron32 04:36, 16 July 2015 (UTC)

Thanks. I previously searched flowstones but they seem to be only inside (caves), don't they ? Blump007 (talk) 04:40, 16 July 2015 (UTC)

Not necessarily. Travertine is a common flowstone that is found deposited at the surface. The only requirement for forming flowstone is mineral-rich waters that flow over the same area slowly for very long periods of time, to allow for precipitation and lithification of the minerals. They are often found in caves because the environment of a cave is often left undisturbed for millennia, but they can form in other environments. --Jayron32 04:48, 16 July 2015 (UTC)

Thanks a lot, that's very informative (+ I added the name of the one pictured) Blump007 (talk) 05:43, 16 July 2015 (UTC)

@Blump007: Thanks for uploading this unusual image to Commons. But please - can you confirm for the description that it was taken in Thermopolis, Wyoming, and when it was taken? We ought to illustrate that article with this photo. I can almost, but perhaps not quite, confirm it is the same one from something like [27]. Wnt (talk) 15:03, 16 July 2015 (UTC)

This is the official website of Hot Springs State Park in Thermopolis, and has pictures of the above formation as well. --Jayron32 00:51, 17 July 2015 (UTC)

Does ESP8266 has an hardware AES engine or not?

ESP8266[28] is a popular wifi-enabled SoC. I'm trying to figure out whether it has a hardware accelerated AES engine or not.

Evidence point to YES:

1. Googling "ESP8266 AES engine" yields dozens of sites saying the affirmative, though most of them likely just copy and pasted that information from somewhere else.

2. ESP8266 contains an ARM Cortex-M4 core. Googling "Cortex-M4 aes" suggests that most manufacturers pair a hardware AES engine with their Cortex-M4 SoCs, so it's likely that ESP8266's manufacturer has done the same.

Evidence point to NO:

1. This reposity[29] contains a purely software implementation of AES, would seems to suggest that there's no hardware AES engine, at least not one that's available to the user. My other car is a cadr (talk) 14:07, 16 July 2015 (UTC)

What happens when the inputs to a phototransistor is shorter than its response time?

Please see this drawing[30]. The first frame is my (admittedly poor) understanding of a phototransistor's response time. Please correct me if there's any mistake.

My question is, what happens when the duration of the input is shorter than the phototransistor's response time? Is there still a delayed response, or is there no response at all? (The latter case being like your car, if you don't turn the key long enough, it doesn't start at all)

Assuming there's still a response, what happens when the input is shorter than even the rise time? Would there still be a cut-off triangular-shaped rise? What would the response waveform look like?

Lastly, is there a minimal input duration below which the phototransistor makes no response at all? My other car is a cadr (talk) 06:36, 17 July 2015 (UTC)

I think you are correct in assuming that you will get a smaller output. You may be able to see this in a frequency response chart. At high frequencies the output will be reduced. Graeme Bartlett (talk) 08:33, 17 July 2015 (UTC)

Electromagnetic radiation vs particle radiation

The quantum of electromagnetic radiation is photon. Then why is electromagnetic radiation not considered to be a particle radiation? --IEditEncyclopedia (talk) 06:46, 17 July 2015 (UTC)

It is, you use the theory that is most useful to you. Graeme Bartlett (talk) 08:16, 17 July 2015 (UTC)

In our article Radiation, three types are described in the lead paragraph: electromagnetic radiation, particle radiation and acoustic radiation. EM radiation is not included in particle radiation. --IEditEncyclopedia (talk) 08:37, 17 July 2015 (UTC)

My reading of that lede is that what are being give are examples, which are neither exhaustive nor necessarily mutually exclusive. Notice that examples given of particle radiation include β radiation which comprises electrons, but electrons can also be interpreted as waves. These phenomena are neither "pure" particles nor "pure" waves, but something else that appear to be either, depending on how you look at/detect them: see Wave-particle duality. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 12:57, 17 July 2015 (UTC)

half life

Why is half life in first order reaction independent of initial concentration but not other order reaction? — Preceding unsigned comment added by 36.252.1.178 (talk) 08:28, 17 July 2015 (UTC)

In first-order reactions the rate of reaction is proportional to the concentration, and the rate of change of the concentration is the same as rate of reaction. You can see from the formula that the left over is proportional to the initial amount. This results in an exponential decay of the initial product. SO for half life look at the t for e^-kt=⁠1/2⁠. With other orders of reaction the relative rate will change on concentration. You can reverse the formula so C=C_i×⁠1/2⁠ after a half life for each C_i. Take the derivative of this. You will get rate of change of C is then proportional to C_i and not C_i² or any other power. Graeme Bartlett (talk) 08:39, 17 July 2015 (UTC)

In case of first order reaction, if initial concentration is $a$then after first half life time it will become ⁠1/2⁠a and after same time it will become ⁠1/2⁠ *⁠1/2⁠a and so on.

Then what is the similar physical interpration for other case (for those dependent on initial concentration)? Does it change continously for a same rxn with time or not? 36.252.1.178 (talk) 09:04, 17 July 2015 (UTC)

for second order the reaction rate is proportional to the square of concentration, for example sulfur monoxide reacting to form disulfur dioxide. Then the rate will drop off much more rapidly. But for zeroth order the rate is constant no matter what the initial concentration (within limits). Graeme Bartlett (talk) 12:53, 17 July 2015 (UTC)

Supermassive black holes

I was looking at the supermassive black holes article and I see no mention of the contribution of dark matter to their size. Has anyone estimated how much WIMPs would contribute to them, would it just be in proportion to the amount of dark matter in the galaxy or quite different? Dmcq (talk) 09:42, 17 July 2015 (UTC)