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April 26

Incremental cost of ice drilling

Years ago I used to work on ice cores. An early deep core, e.g. GISP2 (3000 m), had a full cost of retrieval of about $60M, making each meter of ice nominally worth about $20k. Of course, deep cores are much more expensive than shallow cores. In addition, there has been much improvement in ice core technology and infrastructure. I've heard that projects like the Rapid Access Ice Drill (RAID) [1] for ice cores, and the fast hot water drill projects (e.g [2] for subglacial access, but not coring) have made the cost of ice coring and ice drilling much lower. However, I have had trouble finding specific information on current costs. What is the incremental cost of collecting a 100 to 200 m ice core these days? Alternatively, what is the cost of drilling through 100 to 200 m of ice to reach the subglacial bed if one is willing to discard / destroy the overlying ice? Dragons flight (talk) 09:44, 26 April 2016 (UTC)

If you really want the marginal cost, I think you'll have to do some deep-diving into research program budgets. The way to approach this is to look at the cost structure of the project: how much money is overhead, how much is capital outlay for specialized equipment, how much is variable cost for labor, fuel, travel and transportation expense, equipment operation? I'm tempted to say that the cost is dominated by overhead, which implies a very small incremental cost for each additional unit of sample retrieved. Many of the programs listed, e.g., in the NOAA data set archive were part of publically funded research projects, so if you look for their budgets (e.g. by chasing down the individual grants cited in each author's research-publications), you'll probably find their accounting summaries. It seems that it would be a research project just to track that information down, let alone to distill it into a meaningful average across a large number of recent sample-retrieval missions.

More to the point: do funding agencies or researchers really think in terms of unit-cost per meter of core sample, or are they more concerned with other more abstract metrics like "scientific merit per Government-dollar"?

Nimur (talk) 11:49, 26 April 2016 (UTC)

I recently had an idea for some interesting glacial work. (Or at least I think it is interesting.) However, it would require drilling a substantial number of holes 100-200 m through ice. I'm trying to get an idea of the feasibility of the idea. If it is a $10M+ project, then I would probably just abandon the idea as being too costly to be worth pursuing. If it is ~$1M project, then maybe it is worth trying to advocate the idea to other people. (As I don't personally do ice core collection, I'd obviously have to get others interested in not only funding the work but also doing the study.) I'm trying to get a rough idea of the costs involved before I waste too much time on something that might be a total non-starter. Dragons flight (talk) 12:42, 26 April 2016 (UTC)

Again, I suspect the cost can scale dramatically. It's much easier and cheaper to drill through 800 feet of rock in Oklahoma than through 200 feet of ice in the middle of a glacier in Greenland. I suspect you could get a lot of good science on a very tiny budget; and if you could make the case for getting better science on a bigger budget, you could probably find the money - money is surprisingly cheap.

Clearly, there do exist organizations who will fund field research of this nature; if you are not already building experience towards the kind of project management to initiate and lead such a project, your best bet may be to attend a conference and find some research collaborators. I'd start at a big conference - like AGU, where you can survey the entirety of the field from multiple different angles - and then gradually migrate to a more specific subject-area meeting. If my memory serves correctly, you are already PI on some other private-sector projects, so you're probably in as good a position as anybody to initiate a field-data-collection program; but funding agencies like specific experience as part of their risk reduction strategy. Find somebody who has the right resume, work with them, and co-list them as a cooperative researcher.

Large projects of this nature are usually preceded by much smaller exploratory programs to establish proof-of-merit; you could try putting out a paper just to develop the idea, and test the reception for the basic premise before burning any large quantity of money on field work.

Nimur (talk) 13:15, 26 April 2016 (UTC)

I know you are trying to be helpful, but you aren't really saying anything I don't know already. I'm trying to put together a sketch of project, before taking it to other more knowledgable people that I hope might be interested. Part of that though is having some idea of the scale and cost of the program. Admittedly it isn't easy to find cost information for something like this, so I was hoping someone might have better luck at tracking it down than I have so far. If not, I can keep looking and thinking of who else to ask. Dragons flight (talk) 14:25, 26 April 2016 (UTC)

To be fair we are more like librarians, not subject matter experts. This is a difficult, deeply technical, question. You seem to have a ton of knowledge about it already - and it's astronomically unlikely that any of the few dozen reference desk regulars will have more knowledge on the subject than you do. So we're definitely not going to be of direct help.

So, perhaps the best way we might be of assistance is if you give us the names of organizations or individual people who are likely to be more up to date than you are - give us any jargon terms that are unique to this line of work. Then let the (impressive) search skills and legendary tenacity of our reference desk "librarians" do the work. An alternative might be that we could find an online forum where ice core drillers hang out and we could perhaps get an answer there? SteveBaker (talk) 15:05, 26 April 2016 (UTC)

(EC)Right, so if you're a real scientist who has done real science on ice cores, then probably none of us know more off the top of our heads than you do, and as Nimur said, this is no small research project in and of itself. Anyway, it's not clear what you have and haven't looked at. You say you know what Nimur told you. Have you looked at this [3] NSF grant? That project is ongoing, and over the last few years "1,511 m of the total 3,470 m of ice at the site has been collected", with about $1million paid out so far. Of course not all the money went to drilling. Have you looked for budgets for other projects NSF PLR has funded? Have you used the NSF award search to search for everything related to drilling and ice cores? I think this [4] is saying that you can get budget info on funded grants via FOIA requests, but I have not tried that and I'm not sure. One of the simplest ways to get budget info would be to contact some of the PIs directly. SemanticMantis (talk) 15:08, 26 April 2016 (UTC)

After browsing around on NSF's Polar Science program and Ice Cores website, I found the U.S. Ice Drilling Program resources for scientists. This is a non-governmental organization whose primary purpose is to support specifically-NSF-funded scientists, and to assist them in budgeting and managing field research.

If you aren't already familiar with their publications, it might help to read through the Long Range Science plan, the Drilling Technology plan, and the listing of expeditions, to get an idea for the typical budgets and scope of support. You can also download their paperwork for research proposals, or contact their representatives. "Your email will be received by the IDPO-IDDO and personnel from IDDO will contact you to discuss your needs and provide a Letter of Support and Scope of Work/Cost Estimate for your project."

NSF's website links to this service, but they remind you that U.S. Ice Drilling Program is not a Government website, and NSF doesn't officially vouch for its accuracy or merit.

In particular - their science program matrix includes an entry for a "Borehole Array" project (multiple borings), and they are planning for that program to require about a "week" of field time, plus a Twin Otter support aircraft. That may help set a lower-bound for the kind of budget - you're talking about funding an aircraft that probably costs around $1500 per Hobbs-hour, plus a crew, for a week, just to get set up at a place that's worth allocating the scientific equipment. In other words, this kind of work is planned to be conducted under the auspices of a major NSF grant with a daily budget in the neighborhood of tens-of-thousands-of-dollars-per-day.

But again - the issue isn't the money - they'll let you use the drills - but the issue is that these kind of ice drills are owned by the United States Government; they are scheduled to be used in specific locations; and if you want to use this unique equipment and the specialized crew who are trained to operate them, you have to go through the effort to get into the "system," so to speak. Your project has to line up with their projects and their objectives.

Nimur (talk) 16:58, 26 April 2016 (UTC)

mastoids

My mother (now 91) & her sister both had "mastoids" when they were young. Her sister almost died from this, & Mom says her "mastoids were removed". According to Mom, her "mastoids" drained externally out of her ear---while her sister's drained internally & almost killed her. Neither of us knew what mastoids are, so we looked it up in Wikipedia. You say they are a bone protrusion on the skull for the attachment of muscles. This is not making sense, & I sure would appreciate a better understanding.

Thanks------aj seaman email address redacted by LongHairedFop, to stop spam — Preceding unsigned comment added by 201.191.91.18 (talk) 14:51, 26 April 2016 (UTC)

See Mastoiditis. The Mastoid part of the temporal bone behind the ear contains air-filled spaces. Mastoiditis is when those spaces become filled with fluid, and must be drained. As noted in the article, infections associated with mastoiditis used to be a major cause of childhood mortality, so the accounts of your mother and aunt are fully in line with that. I hope that helps! --Jayron32 15:04, 26 April 2016 (UTC)

Another weird thing that can happen with mastoids is Cholesteatoma, where skin starts growing in places it shouldn't. That can require a mastoidectomy. SemanticMantis (talk) 15:12, 26 April 2016 (UTC)

What a difference antibiotics have made. Klbrain (talk) 00:12, 27 April 2016 (UTC)

Though alarmingly Antimicrobial resistance is spreading so fast that most if not all of the existing ones may soon be useless. {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:29, 27 April 2016 (UTC)

Volume expansion or contraction for mixing two solutions

What is the volume expansion or contraction when mixing two aqueous solutions of salts or a solution of salt and another of sugar as function of their mixing mass or molar ratio? Are there any data pages on this issue?--5.2.200.163 (talk) 15:33, 26 April 2016 (UTC)

It's a whole lot of messy calculus to do such calculations, but if you want an overview, here's an old ACS article that covers the concept using ethanol-water mixtures as a model. Here is an even older article on volume changes when dissolving various halogen salts. In Wikipedia, you can read about concepts like Ideal solution (for when volumes are additive) and Margules function, and more generally about Chemical potential which is the root concept which affects a whole lot of deviations from ideal behavior in a lot of situations (Ideal gas, ideal equilibrium constant, etc.) --Jayron32 18:29, 26 April 2016 (UTC)

I see that the first article says something about a shrinkage factor whose definition would be very interesting to see. In other sources encountered there was just some mention of a percent expression of this factor, without formula.--5.2.200.163 (talk) 16:34, 27 April 2016 (UTC)

I see also that the article introduction says something about the relation of the concept (shrinkage factor) to established ones like apparent and partial volume. That would be extremely interesting.--5.2.200.163 (talk) 16:39, 27 April 2016 (UTC)

Volume of mixing is a redirect to the Partial molar property article. DMacks (talk) 20:20, 29 April 2016 (UTC)

Phase-transition of water: Supercritical --> solid?

Hey there,

I stumbled about a question today and I can't get my head around it. My Physical Chemistry textbook shows a phase diagram of that indicates, that there is a phase-transition of super-critical water at around 600 k and 10 GPa. Does anyone now, if it is possible to form ice directy from supercritical water?

Thank's --134.61.98.4 (talk) 18:10, 26 April 2016 (UTC)

No, because at no point does the solid-liquid or solid-gas transition happen at or above that temperature and pressure combination. The supercritical transition occurs when there is no distinction between gas-like behavior and liquid-like behavior in a fluid (basically, increasing temperature makes a liquid more gas-like. Increasing pressure makes a gas more liquid-like. Raise both above a certain threshold, and the difference between a gas and a liquid becomes inconsequential, that's a supercritical fluid). The solid phase of water should not be anywhere near these conditions. --Jayron32 18:32, 26 April 2016 (UTC)

As shown at water and carbon dioxide it is entirely possible to have a supercritical fluid to solid phase transition. Generally, the transition occurs by taking a supercritical fluid and subjecting it to enormous pressures until it converts back to a solid. Dragons flight (talk) 19:12, 26 April 2016 (UTC)

So stricken. Thanks for providing a link to the more accurate phase diagram showing the solid-supercritical phase transition. I should probably actually have looked than speaking extemporaneously. I've been correctly chastised. Thank you. --Jayron32 20:15, 26 April 2016 (UTC)

Lighting the grail-shaped beacon, eh? Bad, bad, naughty Zoot! μηδείς (talk) 20:38, 26 April 2016 (UTC)

Next time I try to state my question clearer and provide a diagram myself. But I could find one through my quick search.--134.61.98.4 (talk) 13:32, 27 April 2016 (UTC)

Thank you both. This is exatly what I meant Dragons flight. You don't happen to know where I can get more information about the nature of this transistion or if there are any applications that use it? Can I imagine it to be some sort of sublimation/ re-sublimation? I was under the impression, that supercritical fluids cannot be in equilibrium with other phases, so this somehow makes me curious ;) Thanks again --134.61.98.4 (talk) 19:40, 26 April 2016 (UTC)

Supercritical fluid phase can perfectly well be in a thermodynamical equilibrium with the solid phase. Imagine a cylinder filled with a supercritical fluid, where the piston can be moved in (or out) so that the cylinder volume is reduced (or increased) but none of its contents escape, and the temperature of the contents is kept constant. This process - provided the contents of the cylinder have time to reach equilibrium - is called isothermal compression (or expansion). Let's assume the temperature is above the critical-point temperature. Isothermal compression of the supercritical fluid will cause the pressure to rise until you reach the phase-transition pressure - the pressure at which solid phase and supercritical fluid phase coexist. As you keep compressing, more of the supercritical fluid will condense into solid, but the pressure will remain constant as long as any supercritical fluid is left. If you stop compressing at tha point, you will have an equilibrium mixture of solid and supercritical fluid phases. Further compression beyound the volume point at which there's no supercritical fluid left will cause the pressure to start rising again, as you are now in a solid phase and not in coexistence of solid and supercritical fluid phases. Does this help? --Dr Dima (talk) 20:57, 26 April 2016 (UTC)

Regarding your question where to get more information: at an undergrad/grad level, I strongly recommend Landau & Lifschits textbook, and Zel'dovich & Raiser textbook (this one), but those are not an easy read. At a high-school level, I need to think what would be the best place to start from. --Dr Dima (talk) 21:03, 26 April 2016 (UTC)

This is very helpful, thank you. If I understand you correctly, the transition supercritical fluid --> solid is thermodynamicaly not different from the transition gas --> fluid where the pressure also remains constant until all gas/fluid is gone?

The literature looks good. I'm at graduate level but my area of expertise is actually inorganic chemistry. The second book looks promising, I will definitively check it out when I get the time.--134.61.98.4 (talk) 12:59, 27 April 2016 (UTC)

Here's [5] some interesting video of supercritical water in a "hydrothermal diamond anvil cell". SemanticMantis (talk) 21:40, 26 April 2016 (UTC)

Nice video, thanks --134.61.98.4 (talk) 13:14, 27 April 2016 (UTC)

Reusing lunar rovers

1) Is it true that there are 6 rovers on the Moon now ?

2) How many were in good working order when last used ?

3) Would it be possible to land near one, replace the batteries, and get it to run again ? If so, this would seem to allow us to dramatically decrease the weight versus bringing a new rover, although at the cost of only being able to land where a working rover is present. StuRat (talk) 19:19, 26 April 2016 (UTC)

1. Well, there were three Apollo moon buggies - a couple of Russian Lunokhod rovers from the same era - and the Chinese Yutu rover that failed after the first day or so...so, yeah - six in total.
2. The three Apollo buggies were still in working order when they were abandoned. The first Lunokhod worked for nearly a year - I'm not sure about the second one.
3. Maybe...but electronics don't like to be frozen and most spacecraft die when the heaters fail to keep the electronics warm enough. But getting an existing rover to run again doesn't help if it still has the same set of sensors and cameras aboard. The Apollo buggies only really had a camera aboard - and after 11 months of driving around, the Lunohkod probably gathered as much data as would be useful. What makes most new missions interesting is that they have new instruments aboard that can measure things we couldn't manage previously.

SteveBaker (talk) 19:34, 26 April 2016 (UTC)

3) Then couldn't they swap in new instruments, too ? Still cheaper than replacing the entire platform, I imagine. StuRat (talk) 19:38, 26 April 2016 (UTC)

Lunokhods are still being used, in a sense; see Lunar Laser Ranging experiment. The electronics is probably dead due to radiation exposure, but it's possible that the chassis and motors may be salvaged and reused if needed. --Dr Dima (talk) 21:27, 26 April 2016 (UTC)

This article might be useful. Regarding replacing the instruments of an existing rover, I doubt there would be any benefit. There's a finite amount of time in a mission. You don't want your crew playing mechanic on the Moon when they could be doing more useful work. And there's the risk that they might not succeed in retrofitting the rover, or that it's unusable. Space is a hostile environment. --71.110.8.102 (talk) 22:15, 26 April 2016 (UTC)

Ship of Theseus proves that you can get the rover to work again on the Moon. The rover consists of a finite number of components. Let's name them as component#1 to component#18345. Step one: replace component#1 Step two: test if rover is working again Step three: if rover works then your job is done, otherwise return to Step one and replace the next component. 175.45.116.66 (talk) 00:00, 27 April 2016 (UTC)

On Earth, the NASA Apollo lunar rovers weighed 460lbs and the lander weighed 35,000lbs (For comparison, the Spirit and Opportunity Mars rovers are each about 400lbs Earth-weight). If this is a manned mission (which it's gonna need to be if you're going to start repairing a rover) - then adding a rover to the launch weight isn't that big of a deal...especially since you're going to need to take replacement batteries and whatever other spares seem likely to be needed plus the tools to replace them.

The two Lunakhods each weighed in at 1,667lb - they did have solar panels - which is why Lunakhod 1 lasted 11 months - but what finally killed it was the radioactive Polonium 210 used to keep the electronics warm ran out. Lunakhod 2 lasted 4 months, failing with a cooling problem.

The Chinese Yuto weighed 310lbs - so it would be even easier to ship an entire new one rather than locate and repair it. It's motors (probably) didn't survive the first lunar night - although the rest of the rover carried on working for a few months after that. It also used solar panels for battery charging and a radio isotope source for keeping things warm through the 14 day solar nights.

Sending a spirit/opportunity look-alike - with a likely 2000 day mission life - would make a whole lot more sense than repairing a golf-cart that doesn't have useful sensors - and doesn't even have solar panels to rechargeable its' batteries. However, they'd require some redesign for surviving the long lunar nights without freezing up.

Given the ungodly cost of sending humans to the moon, the cost per hour to have them there is enormous. Having them spend time repairing a rover that could easily be replaced (and with vastly higher utility - newer sensors, fancier electronics, etc) - with not much confidence that it can indeed be repaired at all - it just doesn't make sense. SteveBaker (talk) 03:43, 27 April 2016 (UTC)

There can always be some combination of circumstances that motivates people to do something. For example, there you are making a routine crew exchange run to the Chinese base at the Lunar pole, when a minor course correction turns into an explosion. Your orbiter is heading directly at the Moon, and you can't get the rockets working. So you herd everybody into the lander (minus whoever you arranged to draw the short straw) and just manage to clear the Moon, but you're in an equatorial orbit. You land at whatever site you can reach with usable materials. Just so, you're looking at a moon rover and you have a trunk full of tools and solar panels. And, oh, seventy-two, nay, make it ninety-six hours worth of air. Having 5,000 miles to the base and going about 5 mph, this is a problem, but hey, you might rig some CO2 scrubbers out of your cargo. Or stop at some abandoned lander on the way. And NASA can hear your suit radios, even if you can't hear them, and might be negotiating for a rescue from the Chinese. Or have a plan to drop a care package. In any case ... better get working on that moon rover, time is ticking. :) Wnt (talk) 10:16, 27 April 2016 (UTC)

So when is this novel coming out, Wnt? (Hey, it worked for Andy Weir). {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:32, 27 April 2016 (UTC)

Ha, I'd give that book a shot too :) SemanticMantis (talk) 16:15, 27 April 2016 (UTC)

@87.81.230.195 and SemanticMantis: This isn't really my field, so getting all the lingo right would be tough. Doing research to see which rover parts endure and which don't, whether a plausible portable 3D printing technology can replace them etc. is tough. Getting characters right is really tough. But if enough people were interested enough, we could try setting it up at WikiBooks as a collaborative writing experiment. We might even work in that super-durable glass disc holding all of Wikipedia somehow. (probably crack it in half and use it as mirrors to signal to each other. :) ) Wnt (talk) 18:31, 27 April 2016 (UTC)

No...they're hoping that the information they need is encoded in one of the roughly 6000 articles that we have on Japanese railway stations.

Well, the surface area of the moon is about equal to that of North America and Europe combined - even if you are on the earth-facing side - you're looking for things the size of a small car in an area the size of Europe. I kinda suspect you'd need to be either extremely lucky - or to endure a LONG diversion to find a handy rover...and I still maintain that their electronics would be frozen to the point of destruction. On the moon, an unheated rover would be chilled down to -150 degC for a long time - even the most rugged military-grade electronics are junk if you let them get below -55 degC.

Still, it evidently worked for Mark Watney as he took a little sojourn on Mars. But then Martian nights aren't two weeks long and there is at least some atmosphere to help retain the heat. SteveBaker (talk) 22:33, 27 April 2016 (UTC)

One nice thing about sci-fi is you can steer around these problems in the fourth dimension, i.e. postulate, as I hinted above, that routine equipment for a moon base includes a small 3D printer capable of producing electronic circuit boards (or some functional equivalent). Wnt (talk) 11:04, 28 April 2016 (UTC)

Why exactly can't lunar rovers handle cold ?

Considering the expense of getting them there, I'd think they could be made out of a platinum-iridium alloy with zero coefficient of thermal expansion, at minimal additional expense. So, then, what about cold destroys them ? StuRat (talk) 01:19, 28 April 2016 (UTC)

Hehe, NASA would love platinum and iridium, if only they would go on a diet before launch. There are other materials with negative thermal expansion - I don't see a list here for zero, but I suppose it can be arranged. But I don't know if you can make electronics out of them. Wnt (talk) 10:56, 28 April 2016 (UTC)

April 27

What is the most time which recorded about human being without sleeping?

I use an application of neuroscience quiz. One of the question is about the time that recorded about human being who went some days without sleeping. The options were 6 days, 7 days and 11 days, while the correct answer was 11 days. I would like to get a source for this thing (11 days). 93.126.95.68 (talk) 01:53, 27 April 2016 (UTC)

The source is very likely this: Randy_Gardner_(record_holder). Also noteworthy is that this is, apparently, for a healthy individual; people with severe disorders such as Fatal Familial Insomnia are probably excluded, as are people in a Persistent Vegetative State or coma (indeed coma is not sleep). --Dr Dima (talk) 02:14, 27 April 2016 (UTC)

Why do transmission substations gets overheated during black outs?

I would like to know why the transmission substations gets overheated as said in this lecture(Slide 5) when blackout occurs in step 4 since the demand of current can't be meted.Could anyone help me.JUSTIN JOHNS (talk) 10:39, 27 April 2016 (UTC)

Substations are carefully tuned so that their input equals their output; they don't have infinite storage capacity. If something happens downstream so that the output of the station cannot be accepted -- let's just say a power line breaks -- the substation is suddenly taking in more power than it can transmit, and that power has to go someplace, and that someplace is heat. So now this substation must shut down or it will melt. Which means the substations that were sending to this substation don't have anywhere to send their excess electricity. So they shut down too...cascading blackouts... --jpgordon^{::==( o )} 14:50, 27 April 2016 (UTC)

For that answer please see "not even wrong". A substation is a transformer and stores nothing whatsoever. 91.155.193.199 (talk) 16:17, 27 April 2016 (UTC)

No capacitors? Really? --jpgordon^{::==( o )} 16:37, 27 April 2016 (UTC)

Really. A capacitor can store a mere pittance of energy. In power distribution, capacitors are used for power factor correction, not to store even one second's worth of anything. Capacitors don't store no AC. 91.155.193.199 (talk) 16:48, 27 April 2016 (UTC)

OK, so why don't _you_ answer the question, rather than just snarking at details? --jpgordon^{::==( o )} 17:24, 27 April 2016 (UTC)

Did a while ago. Not that that is a prerequisite for pointing out a wrong answer. 91.155.193.199 (talk) 17:32, 27 April 2016 (UTC)

@Jpgordon: That almost makes sense... but it doesn't. Because if the substation "shuts down", where does all that incoming power go? Why can't it just shut down partly, send some of the power wherever the power would go if it shut down, and just take some to pass downstream? I'm sure there's a good engineering reason but it has to be more complicated than what you're saying. Wnt (talk) 15:18, 27 April 2016 (UTC)

That Powerpoint slide is not the clearest thing I have seen. My guess is that there is an area that is served by both local and remote power generation. When remote generation fails, local generation is overwhelmed and shuts down as well. Should see the original sources that were used to generate that Powerpoint slide to tell for real. 91.155.193.199 (talk) 16:48, 27 April 2016 (UTC)

Yes, that's a reasonable guess, but local generation is not mentioned in the PP slide. What the slide tells us is that the transmission stations were overloaded. That's because one transmission station feeds power into the area from one source, so if three sources (the slide tells us) were down, the remaining transmission stations (we don't know how many) each had to transmit more power (from where, we don't know, but there must have been at least one source still live) into the area to keep it live. Therefore some of the remaining stations overheated and shut down. The transmission stations in turn feed transformer stations. With some transmission stations out of action, that left fewer transformer stations than normal trying to supply the same area, so those stations in turn overheated and shut down. Note the distinction between transmission stations, which are switches, and transformer stations, which change the voltage.--Heron (talk) 17:46, 27 April 2016 (UTC)

Good point, and part of the complete answer to the OP's question, "Why do transmission substations gets overheated during black outs?" (sic).

The full answer is that transmission station switches are rated to carry so much electrical power or wattage of electricity, and no more. They're set up so that a transformer feeds them, and distributes some of the power passing through it (not stored in any way, a transformer's just a way of using electromagnetic induction to change the alternating current passing through it from one voltage to another without storing any power - though some power is dissipated through Joule heating of the windings of the transformer as the current increases and the voltage drops in the secondary windings of the transformer) to several switches which distribute power down through power transmission lines, ultimately to where the electricity is used.

When one of those switches fails or ceases to have power passing through it (as when one of more transformers downline from it fails and no longer draws current), it sometimes happens that more current flows through the other switches (for one of several possible reasons), which increases the wattage through those switches above their design limits (the voltage being about the same, but the current dramatically increased), so that Joule heating through the current-carrying parts of the remaining live switches increases accordingly beyond the temperature the switches were designed to work under, and they overheat.

This also works at the level of entire transmission stations - when one entire transmission station fails (no matter how), electrical power load can be shifted to other stations, and they can sometimes be subjected to current demand above their design limits, so that switches can get overheated and fail. That's one of the possible ways cascading power failures happen. loupgarous (talk) 18:33, 27 April 2016 (UTC)

@Jpgordon Oh really? The substations shown in the slide are transformers and the initial failures are upstream. Transformers have no power storage capacity (beyond one AC cycle) and have no problem with zero output load. There is no "excess electricity" involved, only cascading blackouts when substations shut down rather than supply excessive power demands. AllBestFaith (talk) 18:58, 27 April 2016 (UTC)

Yay! I was wrong about something. "The quickest way to get a correct answer on the Internet is to provide an incorrect one." --jpgordon^{::==( o )} 19:02, 27 April 2016 (UTC)

Aye, that would be Cunningham's law [6]. Your original answer did make sense to me, and I would have probably believed it if that was the only response, so this is an interesting thread. Of course it's totally fine to accidentally illustrate Cunningham now and then, but IMO we should all make it a point to not participate too heavily on either side (e.g. pointing out errors only [7], posting under the influence of the Dunning–Kruger_effect etc.). I'll also note that though I see several wikilinks above, none of them seem to refute your answer on their own. So even with your acknowledgement of incorrectness, we're still kind of trusting in the authority of strangers who know how to talk a good talk. And that's not to say I distrust the further refinements, just to point out how hard at can be to support a specific answer with a specific reference :) SemanticMantis (talk) 20:00, 27 April 2016 (UTC)

No need to link out to meta; Cunningham's law is blue:) DMacks (talk) 02:24, 28 April 2016 (UTC)

Ah ne'er so dire a Thirst of Glory boast,

Nor in the Critick let the Man be lost!

Good-Nature and Good-Sense must ever join;

To err is Humane; to Forgive, Divine.

-An Essay on Criticism, Part II , 1711, Alexander Pope (my bolding).

Wikipedia has an article about load shedding in electric transmission systems that cannot meet peak demands. I trust that providing a relevant reference does not strike jpgordon as another snark. AllBestFaith (talk) 15:34, 28 April 2016 (UTC)

Yeah all answer points out one single thing and that's 'the overload of current through these transmission stations was the cause of it's overheating'.I couldn't get how the grid can't meet the 'demand' as given in step 4 and 5 of the lecture(Slide 5).Does the author mean to say about the user's demand or about the current demand?

Can we stop this overheating by refusing the current to flow through these stations if a power failure occurs in one source?JUSTIN JOHNS (talk) 09:01, 28 April 2016 (UTC)

Yes, if a sufficient number of end users have smart switches that allow the distribution company to switch off the less essential consumption at times of overload, then the transformer could be kept at a safe temperature. The current flow is determined almost entirely by the end users, since the regulations in most countries do not allow the voltage to drop below a certain level. A transformer cannot "refuse" current. It's impedance on the input side is determined by the current flowing out to end users. Dbfirs 13:19, 28 April 2016 (UTC)

The important thing being the current flow through both the transformers and transmission switches. Joule heating causes current through a conductor to increase as the square of the current passing through it, so that the transformers and switches both tend to overheat when they're carrying more current than they're designed to carry (the voltage being relatively constant assuming no issues at the generating stations and high-tension distribution network). Heat in reactive loads such as transformers and resistive loads such as switches increases as the square of the current passing through them, which is why when one leg of a power distribution network fails, the other legs which parallel it immediately get hotter (if load is shifted through them from parts of the network which had been served by the failed leg). Overheating of the remaining legs can cause cascading power failures. loupgarous (talk) 18:57, 28 April 2016 (UTC)

In addition to switches which heat up when they carry high current, actual conductors heat up, sag and fail. Transmission lines also have other devices in series which can heat up and fail, such as current transformers which are connected to monitoring equipment and to protective relays, and wavetraps, which isolate radio frequency control signals passing along the transmission lines. They may have series reactances (inductors) to limit fault current if a transmission line shorts to ground .Some transmission substations have transformers which step up or step down the power from one transmission voltage to another, such as 765kv, 345kv and 138kv. Some transmission substations have 138kv phase shifting transformers which can carry 300 megavoltamperes, and can force the power to flow in the desired direction, within limits. Utilities run contingency studies to see which of these circuit elements become the limiting factor for various situations, such as the simultaneous outage of two transmission lines, or a line and a generating station. They upgrade as necessary to ensure a robust and reliable system. When more things are out of service than these design contingencies allow for then immediate load shedding is required to prevent widespread prolonged outages and equipment damage. If he operator hesitates to drop load because of political considerations,or the operator does not have access to actual system conditions such as breaker openings and overloads, or if non-technically sophisticated higher-ups forbid load shedding, then widespread blackouts may result. Edison (talk) 03:06, 29 April 2016 (UTC)

Can playing too much on the keyboard induce bodily injuries?

Is it possible to play for several hours or the whole day hours without sore arms and hands and fingers? 140.254.77.204 (talk) 14:46, 27 April 2016 (UTC)

(It's not clear whether you mean playing music on an organ/piano or video games on a PC/laptop.) I suffer from "mouse finger". That is, the pointer finger on my dominant hand gets sore at the tip, both from typing and using the mouse. I wouldn't call that an "injury", however. I try using other fingers to click on the mouse and type, to minimize the pain. StuRat (talk) 15:34, 27 April 2016 (UTC)

Like most things, you have to learn how to do it. An experienced pianist will have an exercise regime designed to strengthen hands, arms and shoulders, and the length of time he/she can play will have been built up gradually so that the body becomes accustomed to it. 81.132.106.10 (talk) 15:44, 27 April 2016 (UTC)

You may be interested in reading about repetitive strain injury, and perhaps carpal tunnel syndrome, which is associated with repetitive wrist movement. SemanticMantis (talk) 16:13, 27 April 2016 (UTC)

See the warning labels on some keyboards and not moving the whole body is covered by evolution with a reduced amount of food, only. See such diseases those number increases with the body weight. --Hans Haase (有问题吗) 19:54, 27 April 2016 (UTC)

People could try the simplest solutions first. In the days of manual typewriters, sectaries typed all day, every day. Cutting down and gluten and dairy containing foods often helped enormously. Maybe this why so many took to eating crispbreadlike Ryvita instead of ordinary bread – not to keep down their weight (most were skinny-as-rakes already) but they felt better as it contains very little gluten. Also, this may be why they had such beautiful figures, as people who are sensitive to gluten tend to put on weight and become pair-shaped. This maybe 'OR' on my part and based on straw-poll observations yet others appear to agree. [8], [9] What both of these articles fail to mention however, is that our modern diet is deficient in Omega III oils. Snake Oil (derived from the Chinese Water Snakes) is rich in these, which was why it was useful in treating joint pains. The charlatans that sold 'patented' medicine duly tried to ridicule it to increase their own sales. Yet joint pain is often associated with too little Omega III in the diet. Also, keeping the keyboard tilted reduces the amount of flex required in the hands.--Aspro (talk) 21:08, 27 April 2016 (UTC)

...You're joking, right? WP:MEDRSes please. Ian.thomson (talk) 06:58, 28 April 2016 (UTC)

Computer keyboards might be more likely associated with the carpal tunnel syndrome. Piano players more with their fingers. A keystroke on a piano drives the whole hammer. Problems in result are known for the old famous composers and pianists who played the piano all day. --Hans Haase (有问题吗) 06:51, 28 April 2016 (UTC)

Any piano player who uses only or even predominantly their fingers should give up and start again. The whole hand, the wrists, the forearms, the upper arms, the shoulders, the back, the buttocks, the legs and the feet are all involved. Not to mention the brain, the eyes and the ears. -- Jack of Oz ^{[pleasantries]} 23:34, 28 April 2016 (UTC)

Top bottom wing(s) of a plane

1. The F22-Raptor has the wings v-shaped, why are they not straight? -- Apostle (talk) 20:16, 27 April 2016 (UTC)

See Delta wing. Basically, it's because straight wings wouldn't work properly at the speed of the F22 (or any other modern fighter). Tevildo (talk) 20:21, 27 April 2016 (UTC)

When you have to pitch up the Nose in an small aircraft, like when starting or landing, the body will work like a Windshield for a straight up Wing far behind. There is much more airflow at the sides and thus such V-Wings are more effective. Ofcourse these positions makes it more complicated to steer as you dont get a simple yaw windforce but these planes are flown with computersupport today so they can be handled easy nomatter such complicated aerodynamics. B.t.w. the Boeing F/A-18E/F Super Hornet and Lockheed F-117 Nighthawk have these V-Wings too. --Kharon (talk) 01:26, 28 April 2016 (UTC)

Okay, thanks peeps -- Apostle (talk) 07:33, 28 April 2016 (UTC)

Before there was fly by wire, one solution to the problems of delta wings at slow speed was variable geometry or swing wing configuration, invented developed by Barnes Wallace and used in the General Dynamics F-111 Aardvark, Panavia Tornado and Grumman F-14 Tomcat. Alansplodge (talk) 12:04, 28 April 2016 (UTC)

Okay, noted. -- Apostle (talk) 18:09, 29 April 2016 (UTC)

Absence of Nipple development - Medical term?

(Nedical disclaimer noted.)

I noted the following from an IP contributor https://en.wikipedia.org/w/index.php?title=Henry_Morgan&diff=next&oldid=717460941, but I am wondering if nipple absence is an actual medical condition, albiet exceptionally rare? Sfan00 IMG (talk) 21:08, 27 April 2016 (UTC)

It is - see Athelia (disease). Tevildo (talk) 21:10, 27 April 2016 (UTC)

Now to determine if it was known in the 17/18th century :) Sfan00 IMG (talk) 21:29, 27 April 2016 (UTC)

April 28

Is it posssible to push in and pull out a hoop in womb, so that liquid can cover an object demi-spherically?

49.135.2.215 (talk) 01:31, 28 April 2016 (UTC)Like sushi

Inserting foreign objects into one's womb is contraindicated. --Jayron32 15:17, 28 April 2016 (UTC)

Theological objectors to its use may be calmed by information that the Intrauterine device is not an abortificant. Its mechanism of action is production of an intrauterine environment that is spermicidal. See Speroff, Leon; Darney, Philip D. (2011). "Intrauterine contraception". A clinical guide for contraception. AllBestFaith (talk) 15:52, 28 April 2016 (UTC)

Is it possible to make chemical reaction, so that equal amount of material can make one-to-one-to-one correspondence?

(technically, I can not surely be back)

49.135.2.215 (talk) 01:34, 28 April 2016 (UTC)Like sushi

Not quite sure what you are asking, but maybe this is such a reaction ?

H + H =  H2

StuRat (talk) 01:49, 28 April 2016 (UTC)

Would the H₂ weigh the same as the 2H? Isn't there some mass change due to binding energy or some such? Edison (talk) 00:03, 29 April 2016 (UTC)

An extremely tiny mass change perhaps, but would it be enough to be detectable with the equipment in your average chemistry lab ? StuRat (talk) 16:16, 29 April 2016 (UTC)

A mass change due to binding energy would accompany a nuclear process, but not a chemical change like this. Certainly no mass change detectable in a typical lab would occur, but then generating free hydrogen atoms is not something for a typical lab either. Note that the Law of Conservation of Mass is relevant to this discussion. EdChem (talk) 16:23, 29 April 2016 (UTC)

There is a calculable mass change. There would not be a measurable mass change, at least for any normal amount of material or any actual working scale. Using my handy-dandy appendix C of my 7th edition of Brown, LeMay, Bursten, I can calculate the enthalpy change for the reaction above, from the enthalpy of formation for H (g)(217.94 kJ/mol) and H₂ (g) (0 kJ/mol) at standard conditions (25 C, 1 atm) and find the reaction above to give me ΔH = -435.88 kJ/mol. So producing 1 mole of H₂ gas from lone H atoms releases 435.88 kJ of energy. The molecules thus have lower internal energy than before, exactly 435.88 kJ of it (the first law of thermodynamics is a mean bitch that way) and thus by the famous equation E = mc², their rest mass is now exactly 435.88/(3.00 x 10^{8)2 or 4.84 x 10-15 kilograms lighter. That's, of course, not measurable on any scale you or I will ever handle, but it is literally lighter. Mass = energy IN ALL WAYS, not just nuclear reactions, and that includes bond energy between atoms. --Jayron32 16:33, 29 April 2016 (UTC)}

Locust

on this page Plagues of Egypt#Natural explanations it says 1 ton of locusts can eat as much as 2500 humans. if the average human weight is 70kg then thats 17500kg = 17.5 tons of humans, so 1 ton of locust eat more than 17.5 tons of human. is this a joke or real? — Preceding unsigned comment added by Money is tight (talk • contribs) 02:53, 28 April 2016 (UTC)

That means that it takes as much food to feed a ton of locusts as it does to feed 2500 humans, not that one ton of locusts could eat 2500 humans. Ian.thomson (talk) 02:55, 28 April 2016 (UTC)

Yes, it means they can eat as much as 2500 humans can eat. The second "can eat" is implied. Akld guy (talk) 04:17, 28 April 2016 (UTC)

Maybe it does mean they could eat 2500 humans, I'm sure I saw them eating a human in a film once ;-) Dmcq (talk) 09:16, 28 April 2016 (UTC)

I am happy to confirm that locusts are totally herbivorous. 81.132.106.10 (talk) 11:27, 28 April 2016 (UTC)

I have amended the statement in the article to read: "a one-ton horde of locusts can eat the same amount of food in one day as 2,500 humans can", which hopefully avoids any further confusion. Alansplodge (talk) 11:36, 28 April 2016 (UTC)

The OP has a point - he's arguing that locusts are eating, per pound of locust, much more than humans eat, per pound of human. The source here isn't exactly spectacular: Atlantic's TheWire says "When they get hungry, a one-ton hoard of locusts can eat the same amount of food in one day as 2,500 humans, according to the UN." [10] I mean, I'm sorry, I know it's all the rage to replace humans with machines no matter what, but any article that leaves "hoard" unchanged since 2013 just because it passed the spell checker is not exactly romancing me. Nonetheless, I see the same claim here, which identifies Schistocerca gregaria explicitly for the 2013 outbreak. That source also says that the individual locust can eat its own body weight in a day, which would mean that a ton of locusts can eat no more than a ton of food in a day. short ton, long ton, tonne, metric ton, I'm getting a headache already, but to be charitable, they're implying that 2500 humans can only eat 2200 pounds of food (in day, even!) which gives me serious reason to doubt we have met. Still, I can't eat my own weight in a day (at least, not without going on a heck of diet first), so the locusts do have something on me biologically. Wnt (talk) 16:59, 28 April 2016 (UTC)

Dowsing

Dear sir/Mam,

I want know science behind finding out underground water resources using coconut. I really surprised when I experience this myself, I kept coconut horizontally on my palm straight and walk through land and at specific position coconut tail moves upward and remain straight vertically. This technique called water dowsing, when I searched on Google but could not find satisfactory answer for this one. Please tell me what exactly happened and how it happens....

Regards, Ganesh Gaikwad Mumbai, India — Preceding unsigned comment added by Gangaikwad (talk • contribs) 11:29, 28 April 2016 (UTC)

See Dowsing for our article on the subject. Tevildo (talk) 11:55, 28 April 2016 (UTC)

Since there is water underground just about everywhere, and it's just a question of how deep you have to dig to find it, that makes dowsing impossible to disprove. That is, wherever the dowser claims there is water underground, he is sure to be correct. StuRat (talk) 12:53, 28 April 2016 (UTC)

Under the rocks and stones … —Tamfang (talk) 06:33, 29 April 2016 (UTC)

When the expert well-drillers can't find water but the dowsers can, it indicates that there's something to it. One theory is the dowser is sensitive to the movement of ground water, and unconsciously moves the rod or rods. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:46, 28 April 2016 (UTC)

Evidence, Please.[11] --Guy Macon (talk) 14:16, 28 April 2016 (UTC)

Here's one example:[12] ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:24, 28 April 2016 (UTC)

Yes, sometimes dowsing does work, in that what was indicated by the dowser turns out to be a good place to get water. There is no scientific support for the efficacy, that is outlined in our article. However, there is a good reason why it sometimes works when other methods fail- random chance, and the Texas_sharpshooter_fallacy. Another way of putting it: even a blind squirrel occasionally finds a nut. See also Post hoc ergo propter hoc. SemanticMantis (talk) 14:51, 28 April 2016 (UTC)

Especially if the blind squirrel is male. StuRat (talk) 14:54, 28 April 2016 (UTC)

Whilst not commenting on any scientific basis for this (if there is any), didn't Uri Geller make millions out of dowsing for minerals and oil? Were all these companies simply hood-winked, or did they employ him on the basis of previous results? DrChrissy ^(talk) 15:10, 28 April 2016 (UTC)

Probably "a subset of previous results". That is, he advertised those cases where he was successful and not those where he failed. Infomercials for weight loss products do this all the time, with testimonials from the lucky few who actually managed to lose weight in spite of the crazy diet, and maybe some who just lied to get paid, with a tiny disclaimer below that says "results not typical". StuRat (talk) 16:53, 28 April 2016 (UTC)

Whether scientific or not, there are plenty of people who drill wildcat wells looking for water, hydrocarbons, or anything else. It would be fascinating to find a scientific survey on the statistical success-rate to determine whether the method is, well, methodical. One problem is that of confirmation bias; and with the trouble of any Poisson distribution. If an experimenter will retry a random event until successful, they have a near-100% chance of success... but that's not a methodical way to identify whether their system works, nor if it has any advantage over other methodical approaches.

Regarding Uri Geller: that character didn't exactly "make millions," but he did get a lot of publicity and was seen on TV - and if we're looking for statistically-valid indicators, "as seen on TV" is a sure sign of a scam! Geller's "unique abilities" were scientifically studied at SRI - and you can read what a couple scientists thought - they were published in Nature, (1974). At least a few scientists were convinced that his methods were "better than random chance," but most other scientists disagree with the authors' credentials (they were physicists, not psychologists or statisticians); and there has been immense criticism of their study methods, the statistics, and the conclusions.

Nimur (talk) 15:27, 28 April 2016 (UTC)

The article well summarizes a great deal of evidence for pseudoscience. It should be clear, in any case, that most persons who do dowsing have simply found a paying racket, which in our society is the very definition of success. That said, I reserve a sliver of skepticism of the skeptics because those tests were not conducted with the model of precognition in mind, i.e. it might be easier for a dowser to remember a unique feature in advance, and to remember seeing someone strike water straightaway but have no chance to foresee a hidden mark on an experimenter's paper. Wnt (talk) 17:11, 28 April 2016 (UTC)

Well, let's look at the science. THIS is a careful description of the two-year long "Munich experiment" on dowsing. It started with 500 dowsers, then reducing to the numbers to 46 with the best results. They did more more detailed analysis for the 6 people who performed the best. At each stage, the dowsers agreed with the experimenters that the protocols being used were entirely acceptable - and even when they changed their minds, the scientists would agree to change the experimental setup. So the dowsers have no excuses for any failures.

The original experimenters messed up the statistics and claimed that those 6 people were highly talented - although the other 494 of them were not.

But with more robust statistical treatment, even those six performed marginally worse than chance alone would suggest.

I'd also point out that there is that One Million Dollar Paranormal Challenge - a million dollars sitting in trust at the Randi institute for anyone who can pass their dowsing test. So far four people have been tests - but not one has come REMOTELY close to passing the test. Read: One_Million_Dollar_Paranormal_Challenge#Example_of_a_test_.28dowsing.29) for more details.

CONCLUSION: Dowsing doesn't work - not at all, not even slightly - it's a total and utter bust. Any positive results claimed here therefore anecdotal, flooks, observer bias, rigged tests or flat out lies and deceit. Note that this doesn't stop Amazon from selling you two pieces of bent copper wire (with a sheet of photocopied instructions) for $15.00 (plus $5 shipping).

SteveBaker (talk) 17:33, 28 April 2016 (UTC)

Well, what I meant is that the "no feedback about success or failure" built into the design would frustrate a precognitive model. Even a perfect precognitive would need not merely to learn whether there was success or failure, but to have success be more memorable than failure. Wnt (talk) 18:20, 28 April 2016 (UTC)

I'm a student of the critical thinking arts and "Dowsing" is one of a handful of subjects that has an almost "religious" following. People who know it works can not be convinced by any amount of evidence that it's just not real. It is extremely ingrained in popular culture, The Water Diviner is a recent example, i suspect a very high percentage of the general population believe in it entirely or at least think there's "something to it" that science does not know about, "There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy" is a very popular quote among the peddlers and believers of pseudoscience. . . Vespine (talk) 05:19, 29 April 2016 (UTC)

Regression toward the mean is relevant to the example of the 500 dowsers. Those that were "best" simply were lucky that the random variations went their way in the first tests. As you test again and again the laws of probability will reduce their success rate. The same goes for all other tests of the paranormal where initially some test subjects look successful, but their results drop with time. Sjö (talk) 05:43, 29 April 2016 (UTC)

Remembering numbers

Why is it very much difficult to remember numbers for a long period of time? I am a secondary level student and we have to remember many facts and figures in numbers, so can someone please tell me about it and some ways to improve it? — Preceding unsigned comment added by Sahil shrestha (talk • contribs) 13:01, 28 April 2016 (UTC)

There's a limit to human processing which was first explored by the landmark paper "The Magical Number Seven, Plus or Minus Two"; humans have a difficult time remembering things for a few reasons; but the two most important relevant to numbers are context and size. Very large numbers are hard to remember because the human brain has trouble remembering large sequences of digits, basically about 7 ± 2 is the limit. To get around that, the method known as Chunking is used to get around it. That's why phone numbers are often broken up. In the U.S., the typical phone number has 10 digits. 9195557321 is hard to parse, because it's too many random digits, but 919-555-7321 is more memorable because it is "chunked" into smaller pieces to make it easier to process. The other issue is with context. Numbers devoid of context tend not to stick in one's memory; to make something more "sticky", some random fact needs more facts your brain can connect it to. So, we have various mnemonic devices to do so. Rhymes or poems can work "In fourteen hundred and ninety two, Columbus sailed the ocean blue." makes the number 1492 memorable. One of the most common mnemonic devices to remember many numbers is the Method of loci, where numbers are connected to specific objects in a "memory palace", and as one walks through one's "memory palace", one remembers the numbers by remembering the trip through the palace. --Jayron32 15:59, 28 April 2016 (UTC)

Indeed, it makes the number 28736386354 memorable. Wnt (talk) 17:12, 28 April 2016 (UTC)

Sure, if you chunk it as 287-363-863-54 or some other similar way. --Jayron32 18:12, 28 April 2016 (UTC)

"In fourteen hundred/ And Ninety Two / Columbus sailed the / Ocean Blue? I think you have the wrong meter. :) Wnt (talk) 18:14, 28 April 2016 (UTC)

Sorry. The original poem has no "and".: [13] --Jayron32 18:22, 28 April 2016 (UTC)

Ah, but is that a reliable source? If you search in Google Books you will find many instances of it being quoted both ways, with most of the top hits showing the "and". One of the first hits—with the "and"—is in an article titled Reading for Indian Resistance by Bethany Ridgway Schneider, found in the book A Companion to the Literatures of Colonial America edited by Susan Castillo (this one?) and Ivy Schweitzer; Schneider says the two lines are anonymous, and if that's correct then it'd be hard to know which version is the original. On the other hand, Wikipedia says the lines (without "and") are part of a poem by Winifred Sackville Stoner Jr.; but even if this is correct, Stoner could have incorporated the existing couplet into her verse. I do note that to fit into an iambic meter there should not be an "and". --69.159.61.172 (talk) 21:50, 28 April 2016 (UTC)

Unless you elide the "and" sound into the beginning "n" of "Ninety", then it fits nicely. --Jayron32 00:05, 29 April 2016 (UTC)

2876386354 then. Wnt (talk) 19:05, 28 April 2016 (UTC)

I suggest flashcards. StuRat (talk) 16:58, 28 April 2016 (UTC)

Acne faces

Why do some people get severe acne and the scars to go with them? What causes the severe development of acne? Some kind of gene? Habit? Oily skin? Hypersensitivity? I hardly get any acne. 140.254.77.195 (talk) 14:59, 28 April 2016 (UTC)

Wikipedia has an article titled Acne vulgaris (the full medical name of what is commonly called "acne")> There's an entire section on causes. --Jayron32 15:14, 28 April 2016 (UTC)

OR here, but for me there's a 100% correlation with consumption of trans fats. That is, if I consume trans fats, I get acne. If I don't consume them, my skin is clear. Therefore, I avoid them. StuRat (talk) 16:59, 28 April 2016 (UTC)

I did not know this, but indeed, it is confirmed: [14] I dare say even that awful MEDRS guideline won't leave any room for bitching if we put this one in the article. Fake fat, cooked up over a platinum catalyst... what could possibly go wrong? Olives were invented by Athena... partially hydrogenated oils by Proctor & Gamble. Wnt (talk) 17:17, 28 April 2016 (UTC)

WP:OR In my own case, I've noticed that I would often get an acne outbreak after a cold or another infection -- I wonder why that's the case. 2601:646:8E01:515D:E002:2F3A:1AC5:46BF (talk) 23:53, 28 April 2016 (UTC)

Ayrton fan

How did the Ayerton fan work? And did it work at all, since usually the poison gas was all around? 2601:646:8E01:515D:E002:2F3A:1AC5:46BF (talk) 22:02, 28 April 2016 (UTC)

Well I know next to nothing about this topic, except that trenches were particularly susceptible to gas attack specifically because the gas could accumulate in the trenches, unlike on flat land where it would simply get carried away with any breeze. I'm guessing the fan would provide some level of mechanical ventilation which would carry the poison gas away and out of the trenches much faster and more effectively than just letting natural air currents do it, which if the gas was heavier than air, might take quite a long time. Vespine (talk) 23:13, 28 April 2016 (UTC)

Our Chemical weapons in World War I article has a lot of relevant information, however I could not find anything specifically related to the Ayrton fan, even in the countermeasures section. Vespine (talk) 00:21, 29 April 2016 (UTC)

There were a number of chemical weapons used in WWI, with different properties. Chlorine gas, one of the most widely used, is heavier than air, which is probably what you're thinking of with gas accumulating in the trenches. I think fans might work to blow chlorine gas away from you. I've read some books about WWI, and I've read chlorine attacks had to be carefully managed to make use of favorable winds. Sometimes things went awry and the wind blew the chlorine back towards the side that released it. --71.110.8.102 (talk) 00:57, 29 April 2016 (UTC)

A quick web search turns up [15]:

I did not see the experiments until they had developed, and model "dug-outs" and "pill-boxes" had been built. These could be cleared of smoke with a few flaps of a tiny square paddle or fan. The fan with a flexible blade rather more than a square foot in size was mounted on a T-shaped handle. When smacked on the ground facing the on-coming gas, the cross bar of the handle hit the ground first, the blade flattened out, and sent a puff of air. The friction of the ground retarded the lower part of the puff, which became a vortex cylinder. When smoke rings are formed at the end of a gun, or the funnel of a locomotive, or the lips of a smoker, the central part of the puff advances faster than the edges, and so a ring is formed revolving on itself. Discussing this with Mrs. Ayrton, I asked where the ends of the vortex cylinder were, for I had the impression that a vortex ring must be continuous and cannot be cut. I cannot remember her reply, but it may have been that the under surface of the blade retards the air, and forms an upper vortex cylinder rotating in the opposite direction. But whether the two join to form a ring, I cannot say. An ordinary smoke ring increases in size as it travels, and induces a blast of air to pass through it. It was this that drove the gas back. Of Mrs. Ayrton's originality, perseverance and enthusiasm I was aware, but I found her greatly depressed, and showing a sensitiveness of disposition that was new to me. She could stand up to academical mathematicians, but now she was up against officialism. I must confess that the toy-like models in her laboratory-drawing room seemed a long way from the battlefield. So far as experiments went they were convincing when she showed them to me, and many who saw them, including intelligent soldiers, were impressed. But those who did not or would not come, and those who refused to give the invention a trial...

In spite of the disheartening opposition commonly shown to inventors at this time, several supplies of gas-repelling fans were sent to the front. These were not intended to be merely waved about, and perhaps the name "fan" was unfortunate. The inventor almost accidentally, perhaps intuitively, acquired the knack of using it in the best way, and this needed instruction. One of her assistants from the Central College went out and demonstrated the proper use of the fans, and a few officers were convinced of their value...

Wnt (talk) 01:05, 29 April 2016 (UTC)

Mrs. Ayrton's fan made of waterproof canvas stiffened with cane, with a wooden handle is displayed here but "'The fan was found to have no appreciable effect whatever on the gas cloud: in fact, it was actually worse than useless...' (see C. H. Foulkes, 'Gas!': the story of the Special Brigade (Edinburgh: William Blackwood, 1934), pp. 101-102. AllBestFaith (talk) 07:49, 29 April 2016 (UTC)

It is unfortunate for the troops, but very fortunate for the residential neighbors of the 1920s, 30s, and 40s, that she invented a fan instead of the leaf blower. But is there any actual technological reason she could not have invented the latter, had she thought of it and had the needed resources? Wnt (talk) 11:03, 29 April 2016 (UTC)

April 29

question regarding phsyics

why inertia have very miner effect (as compared to the passenger) on the driver of a vehicle? explanation: it is clearly noted that if the driver of a vehicle applied the brakes . then all of the passengers experience a force on them called inertia. and in the result all the passengers strikes there heads to there next seats,but driver of the vehicle feels very miner effect of that inertia . why?? — Preceding unsigned comment added by 139.190.40.237 (talk) 07:27, 29 April 2016 (UTC)

The driver has a steering wheel and foot pedals to push against, and additionally can exactly anticipate the inertial force she is responsible for as she pushes the brake pedal. So the driver is better placed to react to the inertial force applied; but in all other respects, she is subject to the force in exactly the same way as the passengers. --Tagishsimon (talk) 07:39, 29 April 2016 (UTC)

Agreed. If driver's didn't suffer from the same inertia we wouldn't need driver's side steering wheel airbags. StuRat (talk) 16:13, 29 April 2016 (UTC)

Burning quartz glass

What would it take to make any detectable "bubble" inside a piece of fused quartz glass? Can a DVD/BluRay laser be focused to do this? Bytesock (talk) 07:28, 29 April 2016 (UTC)

You need a fairly high power laser to do that sort of thing, see [16]. Dmcq (talk) 08:44, 29 April 2016 (UTC)

Does that apply even if the bubble only needs to be like 1 µm in diameter and the time to accomplish it can be long? The critical equation is if the amount of energy applied in the form of photons will be larger than the energy removed by thermal conduction at a temperature high enough to distort the material. Bytesock (talk) 14:47, 29 April 2016 (UTC)

Bilbana

What is the latin name for the bilbana tree? Röd Boll (talk) 09:17, 29 April 2016 (UTC)

"Bilbana" does not appear to be the English name of any tree. As far as I can find, it only means car track in Swedish. Looking for trees, I'm seeing Musa balbisiana, a type of banana tree. Ian.thomson (talk) 09:24, 29 April 2016 (UTC)

I did not ask about the English name. Röd Boll (talk) 12:45, 29 April 2016 (UTC)

Ok, in what language do you think "Bilbana" is a name for a tree? Maybe you misheard the name "Bilbana", and it is known as something similar. E.g. biloba - Ginko biloba, or perhaps bilbao - Baobab tree- Adansonia. SemanticMantis (talk) 13:24, 29 April 2016 (UTC)

Yeah the ultimate point is unless we know what tree you're talking about we can't help you. Since this is the English wikipedia, and given the phrasing of your question, the logical assumption is your were referring to a tree called bilbana tree in English.

(To give a counter example, I would likely ask "What's the Latin name for the tree that in Malay is usually referred to by the name of the flowers 'bunga kertas'". Or "What's the Latin name for the tree that is called "pokok bunga kertas" in Malay. I would not ask "What's the Latin name for the bunga kertas tree?")

However it sounds like Ian.thomson did look for the word anyway and didn't find anything. Perhaps you'll get lucky and someone will recognise the name, but since it sounds like the name you're referring to is some obscure name and isn't the name in English, there's a very good chance this won't happen. So some details like where this name comes from or where you heard it, what the tree looks like or whatever will probably be essential.

Nil Einne (talk) 14:34, 29 April 2016 (UTC)

Bilbana is also a town in ancient Arabia mentioned by Ptolemy, but nobody knows where it is now. [17] Alansplodge (talk) 01:20, 30 April 2016 (UTC)

Did any trees grow there? Shock Brigade Harvester Boris (talk) 03:33, 30 April 2016 (UTC)

Magnetic field dependence on recording material?

Will a magnetic recording material that has a higher Oersted (Oe) rating induce a more far reaching magnetic field, after being set or recorded into. Such that a harddisk recording material specified as 1700 Oe the magnetic bit-cell in question reach further into the free space above it in relation to its size. Than say the field of a floppy disk at 300 Oe, in relation to its size? Ie can a harddisk magnetic head sense the magnetic field from a floppy disk surface at a further distance than an ordinary floppy disk head can? Bytesock (talk) 14:59, 29 April 2016 (UTC)

How did the Amazon Reef go undiscovered for so long ?

1) I would expect it to be visible from above, in the air or from space. Is the water particularly dark there, so the reef is not visible ?

2) And the hazard to navigation would seem to have required that it be mapped long ago, do no ships travel there ? StuRat (talk) 16:10, 29 April 2016 (UTC)

95% of the ocean floor is unexplored (for any given definition of unexplored. It is all technically mapped to a resolution of 5km/pixel using satellites). It is not entirely surprising when large structures get missed. It should also be noted that it wasn't suddenly tripped over in 2016 and someone said "Holy shit, there's a coral reef here we totally missed." A few factors, already noted in the article you linked make that concept wrong. First, it wasn't first discovered in 2016. It was first discovered in the 1950s, though at the time it wasn't fully evident that it was a functioning coral reef, just a large underwater structure. Second, as noted in the article you linked, scientists didn't think to look for a reef on said structure because reefs don't usually form at the mouths of rivers, so looking for a heretofore unidentified reef at the mouth of the largest river in the world seemed like a low-probability event, so they probably spent time looking for reefs elsewhere. It should also be noted that "discovered in 2016" is a bit misleading, it's more like "was slowly uncovered over 6 decades and finally published in 2016". Thirdly, it seems the reef is in deep enough water to not interfere with shipping channels because it hasn't interfered with shipping channels. I figured that one out on my own, because there are no reports of ships crashing the fuck into it. --Jayron32 16:21, 29 April 2016 (UTC)

"Absence of evidence is not evidence of absence". Also, coral reefs need to be in shallow water, since they depend on sunlight to fuel them. So, that's why I am leaning towards the idea that shipping routes don't go through the area. Maybe currents coming out of the Amazon make shipping dangerous there ? As for the 95% figure, that applies to the depths of the ocean, not the shallows. And even having been undiscovered until the 1950's is still remarkable. StuRat (talk) 16:27, 29 April 2016 (UTC)

Not really that remarkable that it wasn't discovered until the 1950s. Until the 1950s, the Longest mountain range in the world was undiscovered. That a deep water coral reef was also missed until that time doesn't seem to odd. Until the advent of modern Bathymetry techniques during World War II, the ocean floor was basically entirely unknown. --Jayron32 16:58, 29 April 2016 (UTC)

Coral reefs don't need to be in shallow water -> Deep-water coral. Sean.hoyland - talk 17:15, 29 April 2016 (UTC)

Not the best source but [18] suggests only the southern portion is significantly photosynthetic. Our article suggests something similar with another source. As for depth, many sources suggest 30m-120m [19]. I'm not sure what's the highest reach, but many sources suggest the reef is below the "freshwater “plume”, or outflow, of the Amazon". You can probably work out more by reading the published paper if you can understand it [20]. BTW as for being dark, the answer appears to be yes, according to some sources like the first one because of that very same outflow. Nil Einne (talk) 16:51, 29 April 2016 (UTC)

BTW this source [21] seem to confirm what I semi expected. This outflow is visible from space. (Of course visible from space or in satellite imagery or whatever depends significantly on the imagery system including resolution, lens, sensor size, what the sensor is detecting etc etc as well as the conditions at the time but the point is the reef not being very noticable in such imagery doesn't seem surprising.) Nil Einne (talk) 17:21, 29 April 2016 (UTC)

On shipping: draft_(hull) for Panamax shipping is 12 m. This reef is "30 to 120 metres deep". I don't know if boats commonly go there or not, but I don't think many boats have a draft of 30 m /100 feet below water line. Looks like even the Seawise_Giant (which is one of the biggest boats ever built) had a draft of "only" 25 m. SemanticMantis (talk) 17:37, 29 April 2016 (UTC)

The article doesn't say how deep below the surface the top of the reef is; the 30&ndash120 m range is for the depth of the surrounding water, i.e. to the bottom of the reef. I'd like to see figures on the height of the reef and how near it comes to the surface. --69.159.61.172 (talk) 04:23, 30 April 2016 (UTC)

Adding water to aquifers

I heard on NPR that in California, despite drought, they dump water from reservoirs prior to what should be the rainy season, just in case they do get more rain than they can handle and have flooding. Would it be possible to use this water to replenish the aquifers, rather than letting it run out to the sea ? StuRat (talk) 16:21, 29 April 2016 (UTC)

Here is a website that explains how groundwater replenishment could work. --Jayron32 16:23, 29 April 2016 (UTC)

OK, good, so it is possible. I saw that there is a relatively small project in Orange County, CA. Next Q, has anyone proposed expanding this in areas of the (US) West where aquifers are being quickly drained ? StuRat (talk) 16:35, 29 April 2016 (UTC)

They actually do that already. A major part of the Central Valley consists of permanent wetlands, and there are also specially designated flood zones such as the Yolo Bypass -- but in a wet year there is often too much water in the north anyway. Looie496 (talk) 17:28, 29 April 2016 (UTC)

This is my point. "Too much water" means an opportunity to add to the aquifers. StuRat (talk) 17:32, 29 April 2016 (UTC)

Shepherd's rose identification

In Rural Rides, William Cobbett is very complimentary about the fields of Hertfordshire, particularly the shepherd's rose in the hedgerows - "The hedges are now full of the shepherd's rose, honeysuckle, and all sorts of wild flowers, so that you are upon a grass walk, with this most beautiful of all flower gardens on your one hand, and with the corn on the other ... Talk of PLEASURE-GROUNDS indeed!" In A Year's Residence in the United States of America he regrets its absence from America "No shepherd's rose, no honeysuckle, none of that endless variety of beauties that decorate the hedges and the meadows in England". Now, what I want to know is this - what is our modern name for what Cobbett called the Shepherd's rose? DuncanHill (talk) 19:54, 29 April 2016 (UTC)

Tough one. Googling the name /"Shepherd's rose"/ gets you into old books by the second page. I found another old book that mentioned them in conjunction with blooming foxgloves. Along with the honeysuckle this strongly suggests we are searching for something that blooms in late spring/early summer. By the way, we have plenty of honeysuckle in the USA, and about 20 species are native to North America. Anyway, what are we looking for then? Something that is 1) an early summer bloomer 2) common in UK hedgerows 3)not common in USA at the time 4) Rose-ish by look. So my deductive and consistent guess is hollyhock: No natives to USA, it looks a bit rosy, it's taxonomically a Rosid, and the epithet of the common hollyhock is rosea. SemanticMantis (talk) 20:17, 29 April 2016 (UTC)

Hum, but you don't find them in English hedgerows, and they're not very rose-like. I was thinking of maybe a dog-rose or field rose, or some other native rose. DuncanHill (talk) 20:54, 29 April 2016 (UTC)

Interesting. I was only assuming you'd find hollyhocks in English hedgerows because I see them with some frequency on agricultural field edges here in the states. Oh well, hope someone else can help then. SemanticMantis (talk) 21:37, 29 April 2016 (UTC)

Hollyhocks are a common garden plant in the UK, but haven't "gone native" as far as I know. My guess is a dialect name for dog rose, but I couldn't find any proof. Curiouser and curiouser... Alansplodge (talk) 01:12, 30 April 2016 (UTC)

On the Popular Names of British Plants: Being an Explanation of the Origin and Meaning of our Indigenous and Most Commonly Planted Species, London 1863 by Richard Chandler Alexander Prior (p. 205) lists shepherd's cress, shepherd's needle, shepherd's purse, shepherd's rod and shepherd's weather glass, but NO shepherd's rose! I give up. Alansplodge (talk) 01:12, 30 April 2016 (UTC)

April 30

Can gum chewing remove necessity of ordinary food?

(I will not surely be back)49.135.2.215 (talk) 01:23, 30 April 2016 (UTC)Like sushi

No. Chewing gum instead of eating is like not eating at all (see Sham feeding). Ian.thomson (talk) 01:42, 30 April 2016 (UTC)