Wikipedia:Reference desk/Archives/Science/2014 May 24

= May 24 =

What's the best non-supernatural explanation for Lourdes and Fatima?
Or the appearance in Egypt which many Islamic people believed was a shining Mary on the church roof? How did 100,000 people not notice that the "Sun" started moving in the wrong azimuth? Good G-d, 14 year old me would notice that. Maybe it was a sundog (or a ball lightning)? Sagittarian Milky Way (talk) 00:18, 24 May 2014 (UTC)


 * The best non-supernatural explanation is human error. Observer bias is a well-documented effect.  Humans can and do report seeing things that they are not actually seeing.  This even applies to large groups of people.  Nimur (talk) 00:38, 24 May 2014 (UTC)


 * Stripped of all of the layers of interpretation, the Our Lady of Fátima event consisted of:
 * Three children (aged 6, 8 and 9 years old) who were out herding sheep - who claimed to have seen something amazing.
 * A large crowd of people, desperate to see something amazing, who stood out in the midday sun through many hot summer days and more or less stared at the sun. A bunch of them said they saw something - but (according to our article) the witnesses gave widely varying descriptions of what they saw.
 * So - ignoring all of the other interpretation - the best guess from the facts is that the kids were bored, doing a boring job - so they made something up. The adults were staring into the sun - no surprise that they started seeing things.  They couldn't agree on what they saw...so I don't think there is anything here that needs further explanation.
 * The Lourdes initial miracle was, again, a peasant girl with zero education who was gathering firewood with two younger kids (does this sound familiar?) and claimed that they saw something amazing. As people got more and more excited about this, their stories get progressively more detailed and amazing.  Again, stripped of all of the layers of interpretation - the obvious conclusion is that the kids were bored and made something up.  Anyone who has ever had kids will attest to their vivid imaginations and ability to fuse imagination and reality.  Subsequent stories of cures for people visiting Lourdes and drinking the water, are likely a mix of placebo effect and confirmation bias...along with a healthy interest from the people who live there to "talk up" the stories and bring in more people willing to spend money in their two-bit town.  Millions of people seek cures in Lourdes every year - it would be surprising indeed if there weren't a good number of miraculous recoveries.
 * There doesn't really seem to be any great scientific mystery to solve here. SteveBaker (talk) 00:46, 24 May 2014 (UTC)
 * Agree with responses above. OP may be interested in Shared_hallucination. Maybe if question volume stays low here I'll ask about the wow signal ;) SemanticMantis (talk) 01:09, 24 May 2014 (UTC)
 * Even rational, scientific people are susceptible to observer bias, and sometimes scientists draw irrational or unsupported conclusions. Sometimes, even scientists falsify or exaggerate claims.  But because we have a method, it is easier to determine when we are wrong, so we can correct the records.  We depend on hypothesis, controlled experiment, and repeatability.  When experiments repeatedly contradict our hypothesis, we are responsible for retracting the claim.  "Paranormal" enthusiasts fail to engage in this process, and that is why we consider them "wrong."  The extremity of their claims is not actually the reason we consider them wrong!  Scientists will make incredible claims if evidence and procedure supports the claim.
 * When you look at scientists who write about the Wow! signal - or, even when you read scientific commentary on SETI - the process is diligent. The claims are specific and logical.  The claims do not depend on dubious eye-witness reports or single-case incidents.  When paranormal enthusiasts write about the exact same topics, they draw conclusions that have little connection to actual observation.  Nimur (talk) 14:34, 24 May 2014 (UTC)
 * Children are always making up stuff. See for example, the Cottingley Fairies. The bizarre and rather sad thing is that anyone believes them in the first place.--Shantavira|feed me 08:05, 24 May 2014 (UTC)
 * To our modern eyes, they're obviously cardboard cutouts. But people will believe what they want to. Hence the shockingly large percentage of folks who don't believe we landed on the moon, despite the debunking of every issue the hoax-claimants have raised. ←Baseball Bugs What's up, Doc? carrots→ 20:43, 24 May 2014 (UTC)
 * To me the Cottingley Fairies seem like they might be an exercise of British humor analogous to Sir Bonar Neville-Kingdom (I actually started that little article, and it took me most of an hour to decide he was a hoax, since he seemed overall like an eloquent though uncharacteristically honest advocate of the mainstream of British politics where privacy issues are concerned) Wnt (talk) 23:46, 24 May 2014 (UTC)
 * No, the Cottingly Fairies article is about the true story of two little girls who got caught up in something that got completely out of hand and became a cause célèbre in Edwardian England. Not an exercise in British humour at all Richerman    (talk) 00:04, 25 May 2014 (UTC)
 * To me it's more like the Salem witch trials, though rather less deadly. ←Baseball Bugs What's up, Doc? carrots→ 05:34, 25 May 2014 (UTC)


 * But the point is that kids do this stuff all the time. If you ever met a kid with an Imaginary friend, you'd understand how deep and rich these made-up fantasy ideas become - and how the child can actually come to believe that what they made up is actually true.  The Cottingly Fairies are a great example of that.


 * If you want a scarey modern example, then read Wenatchee child abuse prosecutions - 43 adults in a small, unremarkable town in Washington state - accused of 30,000 child abuse incidents with 60 different kids and resulting three hundred sex-ring court cases...and seemingly all of it brought about by group hysteria, kicked off by children with vivid imaginations and goaded on by interviewers with an axe to grind. From one little girl making up a story - the entire thing spiralled out of control until hundreds of families were implicated in a town of only 32,000 people.
 * Looking at that case, who wouldn't say that the kids in the two incidents the OP linked to were anything other than that. You can imagine the kids making up the story - the proud parents telling everyone about it - the clergymen coming to interview them inadvertently giving them more ideas to work with (just like the child councillors did at Wenatchee).  The town gets whipped into a frenzy of religious fervor - and then they all go stand out and stare at the sun for a while until they start to report seeing things.
 * If an entire town can believe that thousands of cases of child abuse were happening at the hands of friends, relatives and neighbors - why wouldn't you imagine that thousands of peasant farmers in a small portugese town wouldn't see the sun dance around the sky? SteveBaker (talk) 15:36, 25 May 2014 (UTC)
 * A similar notorious "witch hunt" was the McMartin preschool trial. ←Baseball Bugs What's up, Doc? carrots→ 18:06, 25 May 2014 (UTC)

Actually, I'm somewhat confused about what the OP is asking. At Lourdes a young girl reported seeing Our Lady of Lourdes and there were subsequently many reported miracles. Which part of that do you want an explanation for - the apparition or the miracles? At Fatima there was a reported Miracle of the Sun for which there are a number of scientific explanations given in the article. As for "the appearance in Egypt" with "a shining Mary on the church roof" what are we talking about - Our Lady of Assiut maybe? There's nothing about anything on the church roof in the article, although it is a very poor article. And what do you mean by "How did 100,000 people not notice that the "Sun" started moving in the wrong azimuth?" - which apparition does this refer to - Fatima? According to the article, there were between 30,000 and 100,000 people there. Some of them reported various different phenomena and some didn't see anything. Richerman   (talk) 10:45, 25 May 2014 (UTC)
 * Miracle_of_the_Sun states not only wrong azimuth but also elevation. And what's up with the near instant drying? I've never heard of that before, that seems to be what should be reported, due to it's inexplicableness. Eh, De Marchi probably made that up ~1950. It must be okay to lie to save souls.


 * Holy crap, there's two Egypt Maries involving church roofs? (including the obvious fake, Our_Lady_of_Warraq). Our_Lady_of_Zeitoun is what I'm thinking of. Maybe it's a transparentish human construction lit with electricity. Did nobody bothered to go to the roof, or even look at the dang thing through magnification? Sagittarian Milky Way (talk) 22:04, 25 May 2014 (UTC)


 * You don't need an explanation for the phenomenon - the simplest explanation is that there was no phenomenon.


 * It doesn't matter how many highly expectant people (standing in the hot sun, staring fixedly at it) said that they saw weird stuff...what matters is the billion or so other people who happened to glance at the sun who didn't see anything unusual. The sun is the same sun everywhere - so if strange things were truly happening to it, it would have been FAR more widely noticed.  The simplest explanation is usually the best.
 * If just a few people were dehydrated and heat-shocked to the point where they hallucinated - and more of them stared at the sun and saw after-images or whatever - and if they all reported it loudly enough as a miracle - then I'm pretty sure you'd get an "Emperor's New Clothes" effect where each individual who DIDN'T see anything felt that they were left out and therefore invented something that they claim to have seen. This snowballs until nearly everyone claims to have seen something.  (This is called "Pluralistic ignorance"). The fact that they all claimed to see slightly different things strongly backs that hypothesis - the large crowd, mostly making up what they saw from their imaginations would be sure to produce wildly varying descriptions of the event.
 * SteveBaker (talk) 15:13, 25 May 2014 (UTC)
 * A science-loving atheist child could think of "people saw it in Russia or it didn't happen" a very religious child could think of that and say "God changed the see-er's senses - duh" The first one won't convince a single believer. Sagittarian Milky Way (talk) 22:04, 25 May 2014 (UTC)
 * I think that skeptics can be too quick to kill a strawman. For example, whatever the sun was up to at Fatima doesn't have to be the literal Sun throwing a tantrum out in space; it could be some atmospheric phenomenon.  Whether you want to call it chance or prophecy, there are a wide range of neat-looking atmospheric phenomena that change how the Sun looks. Wnt (talk) 14:03, 26 May 2014 (UTC)
 * As a gross example, a solar eclipse is very vivid to those who've witnessed it, but the majority of the world's occupants are oblivious to it, unless they've been made aware of it. But if someone had never seen or heard of a solar eclipse, they might well be skeptical of such a report. ←Baseball Bugs What's up, Doc? carrots→ 14:18, 26 May 2014 (UTC)

The scientific community's past and present views on the observation that most animals, as a general rule, supposedly have the same number of heartbeats
I'm curious about the observation that most animals, as a general rule, supposedly have the same number of heartbeats. In the 1970s, did the scientific community generally accept this observation, or did it generally reject the theory? And today, does the scientific community generally accept this observation, or does it generally reject it? 02:14, 24 May 2014 (UTC)Ac05number1 (talk)


 * Could you point to a source promoting and expounding this theory? I've never heard of it. HiLo48 (talk) 02:29, 24 May 2014 (UTC)


 * Isaac Asimov made that observation (hardly a theory!) in one of his science essays for The Magazine of Fantasy and Science Fiction (which were collected in a series of books). —Tamfang (talk) 03:46, 24 May 2014 (UTC)


 * Heartbeat hypothesis is the article, but you will have to draw your own conclusions from it. Rate of living theory seems to be a related concept (Heartbeat theory even redirects to it). Sjö (talk) 08:47, 24 May 2014 (UTC)


 * Don't many flying birds have a much higher heartbeat rate than land animals? The Hummingbird, for example, has been measured as high as 1260 beats per minute. ←Baseball Bugs What's up, Doc? carrots→ 13:32, 24 May 2014 (UTC)
 * Well Hummingbirds don't live very long compared to a number of land animals, although our article does suggest their lifespan is high for their metabolism. Nil Einne (talk) 19:34, 24 May 2014 (UTC)
 * Regardless, it blows away the assumption raised by the OP. ←Baseball Bugs What's up, Doc? carrots→ 20:20, 24 May 2014 (UTC)
 * It can't be without regard to lifespan, since the assumption raised by the OP is not about heart rate, but actual total number of heartbeats over a lifetime. Small animals with higher heart rates and short life spans are according to the theory roughly equivalent to large animals with longer lifespans and lower heart rates in total number of heart beats/lifetime, - Nunh-huh 05:41, 25 May 2014 (UTC)
 * So hummingbirds have a 3 to 5 year lifespan (typically) - their beat rate slows dramatically at night so over (say) 4 years, their hearts beat 1.3 trillion times. For a human, averaged over day and night, we get about 60 beats per minute - so if we live for 70 years then we get about 2.2 trillion heartbeats. So it starts to look kinda approximately reasonable.  But a typical mouse has a heartbeat about 10 times faster than a human - do mice live for 7 years? No...wild mice live about a year - and carefully looked after lab mice only two years - only very freaky genetically engineered lab mice live for 4 years - so we have a pretty big discrepancy at about 0.5 trillion beats.  Elephants have hearts that beat about half the speed of humans - they don't live for 140 years, usually about the same as us - so they are about where the hummingbird is too.  Perhaps we might argue that "wild" humans wouldn't live 70 years - maybe more like 40...which brings our number close to the Elephant and hummingbird - but still three times that of mice.  Dogs have heart rates around twice that of humans...but they don't live 35 (or even 20) years - so they are also on the low side.


 * So this idea is very roughly right - it seems that most animals live for between maybe 0.3 and 3 trillion heartbeats...an order of magnitude of spread...Meh.


 * There are other similar metrics you come across - and they are always similarly approximate. One is that almost all animals with legs can jump about a foot up into the air from a standing jump.  Clearly there are animals that do quite a bit better and others that do quite a bit worse...but it's a surprisingly close thing.


 * The point is that there are always going to be specialist animals that break the general rule.


 * SteveBaker (talk) 14:58, 25 May 2014 (UTC)


 * I think that there are a lot of related power laws of this type. For example, the smaller the animal, usually, the higher the pitch of its speech; the twitterings of a chimney swift are hard to follow at even quarter speed, where they sound like more of a human scale.  There's also a question of whether subjective time is compressed like the sound waves, i.e. dog years.  Larger animals tend to live longer.  The problem with such laws is that they are only vague approximations; they don't arise as a predictable consequence of evolution, and yet... they remind us that however chaotic the probings of evolution through the space of all possibilities, it follows some sort of overall pattern. Wnt (talk) 14:11, 26 May 2014 (UTC)


 * (Steve misspelled billion.) Asimov's essay, that I mentioned above, remarked that the human count is about four times what's typical of other vertebrates.  (He based his computation on the greatest recorded longevity for each species, not an average, but I imagine that makes little difference in the comparison.)  I suspect that some simple life-extending metabolic trick was selected-for, after the invention of language made grandparents worth having beyond reproductive age. —Tamfang (talk) 01:00, 28 May 2014 (UTC)

Depression and memory loss
is depression is related with memory lost — Preceding unsigned comment added by 106.76.250.76 (talk) 05:41, 24 May 2014 (UTC)
 * Yes, it can be. See Major depressive disorder.  Red Act (talk) 06:14, 24 May 2014 (UTC)

Using liquid nitrogen as a source of nitrogen gas
I'm going to aliquot a reagent that I want to be stored under nitrogen gas (i.e. no oxygen). This lab has no equipment for this purpose so I'd like to assemble something makeshift. Normally we'd use a special container to slow down the evaporation of liquid nitrogen but I want the opposite. I don't suppose I can just pour liquid nitrogen into a glass Winchester bottle without it cracking but what if I cool the bottle to -150 C first? Another issue is that I want the liquid nitrogen to evaporate fairly quickly so I get a stream of nitrogen gas. Will this happen or would it be very slow? A metal bottle would be great but I don't we have one. I'll do this in a fume cabinet. — Preceding unsigned comment added by 78.148.110.113 (talk) 07:28, 24 May 2014 (UTC)


 * I've used small ordinary lab beakers to contain LN2 before, just poured it in slowly to minimise thermal shock. HOWEVER, thermal shock is going to be much more difficult to control in a big Winchester. Pre-cooling with dry ice or something would help, but I suggest extreme care, and would try to find a non-glass alternative. A metal container would be ideal for this, I'd think. Hight thermal conductivity and no risk of shrapnel. But ALWAYS run this past your department health and safety person and don't take random advice of people on the internet as gospel. Is there a chemistry department nearby? They'd be sure to have a argon purged Schlenk line set-up you might be able to use. Fgf10 (talk) 12:25, 24 May 2014 (UTC)


 * Likewise, I don't like the idea of a Winchester. One should design the experiment so that even if a Winchester (or other vessel) brakes, you don't have low viscosity liquid nitrogen freezing your toes off. However. The supplier of your liquid nitrogen will no doubt have a tech desk. They are manned by people who are often both knowledgeable and bored, so would love to spend time advising you -so ask them. It is in their companies interest to help, in order that they may sell you more liquid gas in the future.  Liquid nitrogen isn't really dangerous but as Fgf10  advises don't take random advice of people on the internet as gospel. Your suppler wants to sell you more gas, to tell them your application and your budget (which sounds to me like $0). Failing that:  Emigrate to China.--Aspro (talk) 14:51, 24 May 2014 (UTC)


 * ...and also if it breaks. :-) StuRat (talk) 16:41, 24 May 2014 (UTC)
 * Well spotted. Funny; that if I reed some one else's rightings I can spot their faux par  instantly. But knot when weeding   my own diatribe. Keep it up - as I may - with your help and tuition, make it to third grade. :-( --Aspro (talk) 21:32, 24 May 2014 (UTC)
 * I agree that using glass to contain liquid nitrogen is crazy. I'd bring in a metal pot from home, if the lab didn't have one.  That would be safer than using glass.  (Although I'd avoid cast iron, as it's rather brittle, for a metal.)  Pre-cooling the pot is a good idea, but I'd still expect to get more gas at the beginning, until the pot cools to the temp of liquid nitrogen.  If it slows to too low of a rate, you could put it over a heat source.  You also need to be careful that you can seal the nitrogen in, as too much released into the air will lower the oxygen content.  Good ventilation of the area will also help to prevent this. StuRat (talk) 16:43, 24 May 2014 (UTC)


 * It's not crazy at all and can be done perfectly safe at small scales. It's even done in fancy drinks in clubs etc there days. Issue here is scaling up. Fgf10 (talk) 16:47, 24 May 2014 (UTC)


 * Agreed, it's the scale that makes it unsafe. Also, I suspect they add the liquid nitrogen to water or alcohol in those cases, so it's "coolth" is diluted before it hits the glass. StuRat (talk) 16:51, 24 May 2014 (UTC)


 * "I would like to handle a hazardous material, but I don't have the proper equipment." Have you asked your supervisor, and whoever is responsible for safety in your laboratory?  Broadly speaking, I would strongly suggest not taking any of the advice here except Fgf10's guidance to talk to someone who knows what they're doing&mdash;someone who is familiar with this type of work and the associated hazards. Oh, and don't presume that the sash on a standard fume hood provides more than minimal protection from blast and shrapnel.


 * So to irritated the above. You should not have to ask here on Wikipedia but direct your concerns to your supervisor.  If they say but everyone in this industry  uses  LN2  point that they have duty to educate you to do so likewise.  I would agree that it is much more benign than  liquid oxygen. With LN2 you can put a flask in the trunk and drive home to show the kids how to freeze bananas,  flowers and things then shatter them.. but first you have to discover how not to freeze your toes off- because that can ruin your whole day--Aspro (talk) 22:26, 24 May 2014 (UTC).


 * (I'll note as an aside that most large liquid nitrogen tanks have fittings to dispense gas as well as liquid. If you have an appropriate regulator, that is the easiest and likely safest way to get gas to work with; our laboratory has used this approach for nitrogen purging of instruments when we haven't had house nitrogen on tap.  Again, consult someone who knows what they're doing.)  TenOfAllTrades(talk) 18:11, 24 May 2014 (UTC)


 * This is ridiculous. I've never seen people get special safety training to deal with small amounts of LN2 (<500 ml), and it really doesn't bite - even holding some drops in your hand usually won't cause injury because of the vapor barrier.  Dropped on the floor it will skedaddle all the way to the far side and back causing no damage.  I have never tried and wouldn't recommend dousing someone with it (I imagine that it could get stuck in clothing crevices and cause little burns) but I'd be stunned if they suffered any serious injury.  The key thing is though that you should think Dewar, or at least a thermos - keeping it in something to make it evaporate faster is also nuts.  You never have trouble with it taking too long to evaporate.  With an open Dewar 4 inches or so wide with an inch of LN2 at the bottom, you'll see a clear layer of dry nitrogen gas falling continually around the edge, with the moisture of the air condensing more turbulently above it.  So I imagine you could just take your chemical jar, put it below the lip level into that layer of pure N2, and since the nitrogen gas is so cold it should just pour right into your vial in no time.  I assume you're not looking for 99.999% purity though!


 * Speaking of purity, the one odd trick LN2 has is that small amounts of oxygen in the air will liquefy and enter it when you let it sit out. If you let it all evaporate away, the last little bit will be pretty high in oxygen.  You can just ruin a tissue specimen this way, and I imagine that if you had the wrong chemical something far more unpleasant could happen.  I recommend that if you're dealing with genuinely dangerous or precious chemicals rather than just a "let's see if this works..." test, you go ahead and look for a professional solution for putting them under nitrogen. Wnt (talk) 21:50, 24 May 2014 (UTC)


 * ? ridiculous. This is exactly why we suggest he puts the responsibility into the hands of his supervisor. A small amount of LN2 can increase the local oxygen levels in a confined space (read fume cupboard). The OP hasn’t said what else may be in the fume cupboard. We are not psychic, we just have to go by our experience of the realities of lab  life.  Nice if you work for NASA, where you have a whole fume cupboard to yourself but the OP appears to be asking the question from the point of view “ I've been thrown into the deep end -what do I do?”--Aspro (talk) 22:49, 24 May 2014 (UTC)


 * I certainly hope your fume cupboard is not a confined space. While liquid nitrogen can indeed accumulate liquid oxygen which can then evaporate, the evaporation of the liquid oxygen produces, well, oxygen.  So long as the Dewar is not a primary source of air coming into the fume hood, it should not greatly change the overall oxygen level in the air in there. Wnt (talk) 23:30, 24 May 2014 (UTC)

There are special bottles for cryogenic stuff. It would take a long time to slowly cool down a heavy glass bottle. It's like cooling a superhot brick right from the oven to room temperature. Count Iblis (talk) 13:00, 25 May 2014 (UTC)


 * True, and even supposing that the evaporation rate weren't high enough (which I do not expect as a problem) then I'd prefer something more controlled like taking a metal rod and putting it into the Dewar, so that you could hold the top in your hand or otherwise heat it to control the rate. Wnt (talk) 22:22, 25 May 2014 (UTC)


 * TenOfAllTrades has the right idea. Unless you want to make your sample cold, there's no reason to have it in the same container with liquid nitrogen.  What you want is an enclosed volume that can be purged out with dry nitrogen gas.  You can use the boiloff from an LN2 dewar as a perfectly good source of purge gas.  The purged volume could be any old container as long as it has a suitable inlet and outlet. --Amble (talk) 22:09, 26 May 2014 (UTC)


 * You should use a bottle of gaseous N2 at what ever purity level you require. These are easy to acquire. A supply from evaporating LN2 WILL contain O2 (I think the blueness in the vapor is a sign of such) and if mixed with organics can be dangerous. Also the temperature issue can easily cause cond3ensed water contamination. Juan Riley (talk) 22:18, 26 May 2014 (UTC)


 * Indeed, a bottle of warm dry nitrogen is a lot more professional, and withdrawing gas from a storage tank does make more sense if it is anywhere near your lab. I was going by the OP's "makeshift" idea because sometimes you just want to know if putting something under a mostly-nitrogen atmosphere helps it stay stable for longer.  I should also say that reading  there are some who are not as casual about LN2.  I hadn't even thought about rings, and while I feel skeptical about the claim there that you can destroy "cubic centimeters" of flesh if the liquid nitrogen pours into a shoe, but then again I've never owned a pair of stormtrooper boots... so I may have been too quick to generalize.  Still, the copious vapor production and ultra low viscosity do much to at least reduce the odds of trouble. Wnt (talk) 07:28, 28 May 2014 (UTC)

Alternative energy
Is this real or not? It sounds too good to be true to me. 24.215.188.243 (talk) 19:33, 24 May 2014 (UTC)
 * Yes, (see: Solar roadway) but there are many problems, not the least of which is cost see:http://science.howstuffworks.com/environmental/energy/solar-panel-highway2.htm Richerman    (talk) 20:17, 24 May 2014 (UTC)


 * Things can be real without being practical. For example, humans have already built jetpacks, invisible ink, flying cars, square wheels, and cigarettes.  The benefits of such inventions do not outweigh their numerous hazards and costs.
 * In this case, solar energy in the form of photovoltaic cells built into the roadway is so far from being useful that it's not even listed in the United States Department of Transportation's National Transportation Library section on solar energy. If you want to inform yourself about practical alternative energy solutions as they apply to highways in the United States, you might start by reading the program overviews at the Department of Transportation's research library.
 * You can also read about solar energy at the Department of Energy's website on science and innovation.
 * If you'd like a more tempered view on the subject of the OP's original link, here is a Washington Post article from a few days ago, reporting on the inventor whose video was linked above by our OP. Once you're past the attention-catching headline, the article actually outlines the more sobering realities about costs, maintenance, environmental effects, and the reasons why this inventor's funding was ... discontinued.  It seems, however, that he had enough budget to hire a viral marketing firm to make a ludicrous video before his money dried up.
 * If we wanted to spend hours tearing apart this specific incarnation of solar roadways, our hardest challenge would be "where do we even start?" Just based on the Washington Post article, the crank scientist demonstrates his glass solar-panel roadway invention is "roadworthy" and sturdy by driving his tractor on it.  Well, great... except that it is a tractor, designed with giant low-pressure tires to minimize ground pressure.  Tractors can drive on soft ground and muddy surfaces too.  Can the roadway withstand ordinary highway traffic?  Probably not - but in classic fashion, our rogue inventor has concocted a ridiculous and flashy demonstration with no actual practical implication to distract us from actual analysis of the invention.  There are dozens of other problems with this design that immediately come to my mind.  But, I'll leave it to our other reference-desk regulars to take the rest of this "invention" apart piece-by-piece.
 * Nimur (talk) 20:12, 24 May 2014 (UTC)
 * I wonder how well they would survive if someone decided to take their traction engine or steamroller for a spin? Richerman    (talk) 20:50, 24 May 2014 (UTC)


 * That's a rather biased view of not only the project, and also a poor summary of Washington Post article. It doesn't say why his funding was discontinued. The funding was from Phase I and II SBIR grants, which are for a finite amount of money and time, not ongoing contracts. The fact that they got a Phase II grant suggests the funding agency is interested in the project. Phase III requires getting private-sector funding. According to CNN, they've also done laboratory load and traction tests. Obviously there's still a lot of work to do, but just dismissing it out of hand and then needlessly insulting the inventor is inappropriate. Mr.Z-man 22:05, 24 May 2014 (UTC)


 * If you look on their FAQs here under "how much will you panels cost" it says "We are still in the midst of our Phase II contract with the Federal Highway Administration and we'll be analyzing our prototype costs near the end of our contract which ends in July, 2014". There is also an answer to the question of load bearing properties under "Can your Solar Roadways handle army tanks?" Richerman    (talk) 22:45, 24 May 2014 (UTC)
 * As I'm sure you recall from previous discussions, I'm reasonably well-read on the subject of tank tracks! (I spent an intolerable period of my life in a former career, stressing out over land mines).  For the uninitiated, tank tracks usually exert less ground pressure than an ordinary sports car.  Low track pressure helps in off-road, soft terrain, and makes it harder for enemies to use a simplistic pressure fuse.  But from the FAQ on the SolarRoads website, I can see that the inventor hasn't even correctly framed his answer in context!  The total weight of the tank is completely irrelevant to its effect on the roadway.  What matters is its ground pressure and the materials that contact the road surface.  Nimur (talk) 23:20, 24 May 2014 (UTC)
 * Nope, I probably wouldn't have even read that, and if I had I wouldn't remember what was said by whom. But anyway they say under "How much weight can these panels support? Semi-trucks get pretty heavy!" - we decided to shoot for 250,000 pounds. Both 3D Finite Element Method analysis and actual load testing at civil engineering labs showed that our Solar Road Panels can handle that and more". Richerman    (talk) 23:34, 24 May 2014 (UTC)
 * Here's an article worth reading: Pushing the Limits of Pavement, published by the DOT, from January. You can see how proper engineered road surface tests are performed.  You might also want to read bridge weight limits and per-axle weight limits.  The inventor isn't even using the right language to frame his responses about weight and loading!  And this issue of material strength is just one minute aspect of the many problems of the total system design!  Nimur (talk) 00:31, 25 May 2014 (UTC)
 * What I don't understand is where it says here "Brusaw said his initial target price is $10,000 for a 12 x 12 encapsulated solar panel. If it drops to $6900 during production, he said he could break even with asphalt". Are they just talking about the cost of manufacture? If so, how does that compare to the cost of asphalt which would be a few dollars for a chunk that size? The main cost with building an asphalt road is the preparation and construction, not the cost of the asphalt itself. Richerman    (talk) 00:51, 25 May 2014 (UTC)
 * Ah, it seems they're talking about a 12 foot x 12 foot array of panels (I think) but even so, I didn't think asphalt was that expensive. Richerman    (talk) 01:26, 25 May 2014 (UTC)
 * I think that solar roadways make a lot of sense... with the solar panels being above the roadway, of course. Roof and wall major highways, especially in well-populated areas, with large spans of panels and other materials where they don't make sense to keep in the noise and perhaps even process pollution somewhat, to keep them warmer and free of snow, and providing handy points for illumination at night while eliminating glare by day.  But has anyone actually worked on something like this? Wnt (talk) 21:39, 24 May 2014 (UTC)
 * There's one problem with panels above the roadway. See the third paragraph of Truss bridge for details.  Plus, in places where you have rooves and walls on those highways, you're creating tunnels, and tunnels have their own hazards.  Nyttend (talk) 03:24, 25 May 2014 (UTC)
 * Well, the size of the required tunnel does limit the amount of road that can be covered; still, however you cover a road, it has to be better to do that than to cover a big random patch of ground that otherwise could be a park or residential housing. As for tunnel fires, well, it's not really a tunnel.  You could rig the side panels for quick release with the same low-melting bismuth alloy used in sprinkler systems, and as soon as the flames flashed up toward the roof, all the side panels slide down around the edges of the tunnel and land at either side of the road. Wnt (talk) 19:50, 25 May 2014 (UTC)


 * Oh good grief!


 * I'm sure we could fix the strength issues - that's really not the problem.


 * Each panel costs $10,000 now and is expected to drop to $5,000 - that's for a few square feet. What does a few square feet of asphalt cost?  A typical 60 foot wide road costs $100 per linear foot (including the lighting, signage, etc)...so very roughly they cost $1.50 per square foot .  So this proposal increases the cost of road building by a factor of maybe a thousand.
 * Each year, the US spends around $150 billion on new road construction - around 1% of GDP...increase that by a factor of 1,000 and we're looking at a $150 TRILLION annual cost to build new roads with this stuff...and that's not considering the cost to gradually convert existing roads. The total annual income of all Americans put together is around  $15 trillion.  So even if we spent every single penny we make on building new solar roads (and none whatever on food, housing, transportation or new iPhones!) - we'd only be able to build about 1/10th of our new roads this way and have no money whatever to upgrade existing roads.


 * If we kept to current expenditure and just switched to solar panel roadways, we'd take 1000 years to make just the new roads we need for this year alone!


 * But hey - we'd earn/save a ton of money from the electricity we'd make - right? The video said that if every road, footpath and sport field were converted to this technology overnight, it would generate three times the present energy needs of the USA. Present energy costs equal about 5% of GDP  - so three times that is only 15% of GDP that these roadways would earn...and we need 10 times GDP just to build new roads.  (It's actually a lot worse than that because with all that free energy, the cost of energy would plummet - so we wouldn't earn much by doing it).


 * Furthermore - these panels make energy during the day. How would we store it all during the night?  That's an altogether non-trivial problem.


 * This is a ridiculously stupid idea. Solar panels are a great idea - but you've got to keep the cost-per-square foot down as low as possible - and making them super-strong and integrating lights, LED's power distribution, pressure sensors and god-knows-what-else into them is stupid.  If you really wanted to do this to generate all of the electricity the US needs (rather than three times as much) - then use a strip of the median of every road that's about a third the width of the road and cover it with regular solar panels - their math says that's enough.  The energy generated would be at least as good (probably better because that strong, bumpy glass probably isn't that transparent - and you could orient them toward the prevailing sun direction).  Conventional panels cost $6 per square foot, not $1000 - so instead of it costing us 1000 times what normal road construction costs, it would add about $2 to the $1.50 it currently costs to build a square foot of road...that would double our road building cost - and if we're going to gradually upgrade existing roads, we should probably spend more than that...but it would still be only a few percent of GDP - and free energy for everyone would save about 5% of GDP - so it would be a reasonable investment.


 * Of course then you have to ask why we're building them next to roads when we have all of that boring desert out there in New Mexico that we could cover with solar panels.


 * Sorry - but this is an utterly batshit-crazy idea.


 * SteveBaker (talk) 14:15, 25 May 2014 (UTC)


 * Steve, the touted figure of $6,900 was for one of their original 12'x12' panels, not for one of their more recent smaller hexagonal panels. $6,900 for a 12'x12' panel is about $48 per square foot, not the $1000 per square foot that you came up with.  I'm not concluding that the panels would be cost effective; I'm just saying that their cost shouldn't be overestimated by a factor of 20.  Red Act (talk) 15:46, 26 May 2014 (UTC)


 * Yet another reason why it's crazy is the difficulty in keeping the panels clean. Rubber from tires continually coats our roads, you can even see the dark tread marks on a white concrete road.  And, being horizontal, they accumulate dust, sand, etc.  That could be removed by regular street sweeping, but removing the rubber would require scrubbing the roads.


 * If we forget about solar panels, though, glass roads makes more sense than you might think. It's made from sand, which is in ample supply around the world, unlike petroleum, which is an ingredient in asphalt.  And glass can be made quite strong, and to have a zero coefficient of thermal expansion, which would keep it from cracking due to temperature changes, as concrete does.  I'd use glass bricks, like cobblestones (technically, setts), so they can be replaced as needed, rather than having to patch a road, which doesn't last long, or repave the whole thing.  And water can't trickle into glass, freeze, expand, and crack it, as it does with concrete or regular bricks.  Asphalt could be used between the glass bricks.  The usually problem with asphalt is that it wears away quickly, so the road develops troughs where wheels roll, but the glass would prevent that.  Another problem with asphalt is that it breaks away at the edge, so some type of glass edging bricks could be used there, maybe with a silicone rubber seal between them.  The surface of the glass could be coated with sand, to increase friction.  StuRat (talk) 18:59, 25 May 2014 (UTC)


 * Sometimes an 'obvious' benefit is less so on deeper investigation. One issue with making more durable road surfaces is that you don't want them to wear peoples tires out unduly either.  Here in Texas, the summer temperatures get hot enough to soften 'conventional' asphalt - so they use a harder mix than most places.  This results in higher tire wear and tires here wear out about 5% faster than elsewhere.  Grip is another issue - and how the grip varies with moisture levels is of great concern.


 * Current tire design is based around current road surfaces - and vice-versa - they have co-evolved. Tires might have to change radically if some other road surface were to become commonplace.  But then you get into Path dependence - where even if someone invents MiracleSurface-3000 (tm) that costs half what asphalt does, is good for the environment and never wears out, if it requires that you use MiracleTires-3000 (tm) that are half the price of regular tires and last ten times as long - it'll never happen.  You can't replace the road surface until everyone has the new tires - and you can't use the new tires until all of the roads are resurfaced.  That's a problem you can never escape with a system as large as the road network.  Every change has to be small and evolutionary.  Revolutionary solutions have to be 100% backwards and forwards compatible at every stage - which is a tough engineering challenge. SteveBaker (talk) 13:57, 26 May 2014 (UTC)


 * You raise a good point about other factors of significance to consider. Another example is the road noise levels – some asphalt road surfaces are substantially quieter than others, and glass is not a great material in this regard.  I expect that solving the economics and engineering problems of solar panels and road surfaces separately (even if that means putting panels on top of all buildings) will be better than trying to find some joint solution for a long time to come.  Once we no longer have roof area that can be repurposed, this would change, but until then ... —Quondum 16:51, 26 May 2014 (UTC)


 * Hopefully using asphalt between the glass bricks would absorb the vibrations and make the total system quieter. And I agree that solar panels on roofs makes more sense, since there will be less of an issue with them getting dirty or covered with debris there, and hopefully the power can be used right in that building, eliminating the need to distribute it over large distances. StuRat (talk) 18:07, 27 May 2014 (UTC)


 * BTW, Solar roadway is a dead redirect. - ¡Ouch! (hurt me / more pain) 14:47, 27 May 2014 (UTC)

Cyclophosphamide
Hello, could somebody help me define the pharmacodynamic and pharmacotherapeutic group of cyclophosphamide? I didn't find much about such classification in English literature but have to include it in my presentation of cyclophosphamide. For example, the PD group of Ibuprofen is inhibitor of cox1 and cox2 and the PT group is NSAID. Another example: Indapamide - PD: inhibitor of Na/Cl symporter, PT: thiazide-like diuretics. I thought the PD group might be alkylating agent or nitrogen mustard and the PT group cytostatic drugs (chemotherapeutics) and immunosupressive drugs... I'm really confused, any help and explanation would be appreciated. — Preceding unsigned comment added by Atacamadesert12 (talk • contribs) 22:50, 24 May 2014 (UTC)
 * Try here - where it says it's an alkylating agent of the nitrogen mustard type. It says here it is an alkylating agent with cytotoxic and immunosuppressive properties. Richerman    (talk) 23:23, 24 May 2014 (UTC)


 * Based on our Cyclophosphamide article, I would say that the PT group is nitrogen mustard alkylating agent, and the PD group is alkylating antineoplastic agent. Looie496 (talk) 23:27, 24 May 2014 (UTC)


 * Per the Davis Drug Guide for Nurses, cyclophosphamide is PT: anti-neoplastic immunosuppressant and PD: alkylating agent, nitrogen mustard. Epolk (talk) 04:30, 28 May 2014 (UTC)