The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
How much care is exercised in naming new concepts in quantum physics? (e.g. "wave function collapse")
I understand naming standards like ISO for computer science and IUPAC for organic chemistry, but I don't know any details about the process of naming terms & concepts in quantum physics. Those I've asked in discord/reddit have said quantum physicists have bigger egos than computer scientists or chemists, which I find irrelevant. Hoping to find a more helpful answer here... Thanks, 67.233.34.199 (talk) 16:15, 15 January 2018 (UTC)[reply]
The basic answer is that the person who invents a concept has the right to name it, and often exercises little care in doing so, because people don't usually realize that their new concepts will turn out to be important. The result is that lots of things get poorly named. One of the most egregious examples is theory of mind, which is not actually a theory. Computer science is not by any means immune to this. Standardized naming only applies to things that fall into recognized groups, such as file formats. New concepts, such as agile testing, are named by whoever thinks they are worth naming. The history of the word interface -- as central a concept to computer science as you can find -- is particularly interesting: it came into use because some engineer back in the 1950s couldn't think of anything better. Looie496 (talk) 17:09, 15 January 2018 (UTC)[reply]
It is also worth considering that much of quantum mechanics was originally developed in languages other than English. Important concepts are embodied with non-English words like eigenfunction, ansatz; and even words like the photon and the action and even the quantum are at best "technically" part of the English language, though they all derive their modern application in physics by way of other modern languages, followed by subequent retranslation into our own English-like technical jargon.
When you read about wave function decomposition in German, it reads a lot more like plain language. I frequently wonder if American students of physics would have an easier time if we never used the word-fragment "eigen" for any purpose; many modern math curricula use the word "characteristic" in its place.
The jury is still out on how effective any of this stuff is. Some research implies that students learn better if we vary the vocabulary while teaching the concept. Contrarily, some research implies that students learn worse if we vary the vocabulary while teaching the concept. Here's a research brief from a group recommending that we make introductory-level students write essays about physics vocabulary: The vocabulary of physics and its impact on student learning.
In my experience, I have found that the pioneer researchers do not automatically obtain the privilege of naming the concepts: on the contrary, they reap fame and credit, but it is the forgotten, nigh-anonymous authors of the best textbooks who actually get to name the concepts.
Though you surely believe that Newton and Leibniz invented calculus, you almost certainly recognize the mathematical vocabulary and the symbolic equation conventions used by Stewart. I challenge any novice to read Principia Mathematica and make a concerted effort to recognize when and where our esteemed author applies u-substition! And the very same applies to more advanced physics: just a few weeks ago, here on Wikipedia, we did an etymological dive into the etymological history of quantum mechanics: Who first analyzed the 'particle in a box' model? Again, most readers of Schrodinger's actual writing will not recognize the Schrodinger equation that we all know from our textbooks. Which author actually came up with that name?
And if you read that paper, why, it's right there in plain German, with no bizarre or fancy techno-babble jargon! There is no "quantization," and the author takes pains to avoid the word "whole," explaining in his opening that the quantization is the natural consequence of the system. Now! This is troublesome, because in the English language, a whole number is a mathematical word for a natural number (or integer); how can we possibly translate this concept into our language, in which the natural number occurs naturally without a priori requiring it to be a whole number? The trick is to first learn German, and then to learn quantum physics, and it will save you a lot of conceptual headaches - especially when you study translational invariance.
I'm trying to identify a plant, shown in the following pictures, which resembles arecaceae, but it isn't a member of this family. The pictures were taken somewhere in ancient Caesarea in Israel, in October 2017. Also the purple cluster shown doesn't look familiar, at least to me. I'll be glad to get clear & professional identification. Some Yucca, may be ? Not sure.
בנצי (talk) 15:12, 15 January 2018 (UTC)[reply]
a. I don't know who aligned the pictures - thank you (you saved me another question, a technical one, regarding this).
b. I tend to agree with the 2nd identification - Yucca aloifolia. It seems the only Yucca bearing such fruit cluster, in shape & color as well. Also the comment you make regarding acclimatizing the plant to the region sounds true to me.
c. In Yucca appears the following wonderful Yucca species, but with no name - who knows which one is this (see below) ?
I was reading our article about the Thomas Fire and I'm curious about some of the statements made regarding fire containment. How is it calculated? Is it a measure of the active perimeter under control? I understand there's a technical definition being met, but to the layperson saying that a fire is 10% contained is a bit like being 10% pregnant. I assume we have an article about it, but I can't seem to find it, having gone through glossary of wildfire terms, wildfire, fire control, and fire suppression. Fire containment just redirects to firefighting. Matt Deres (talk) 17:27, 15 January 2018 (UTC)[reply]
Sounds like an article I should think about drafting...
You are correct in saying that wildfire containment is calculated as a percentage of the active fire perimeter which has, in the view of the incident commander, sufficient fire control line around it. (Note that this does not always mean that line will hold up under any conditions.) These are always somewhat rough calculations, but they are aided by GIS, satellite and aerial tracking methods; major wildfires in the United States are mapped nightly by United States Forest Service infrared scanning aircraft when available and there are several NASA satellite programs which aid in remote sensing of wildfire, including the Moderate-resolution Imaging Spectroradiometer and the Visible Infrared Imaging Radiometer Suite. Note that the definition of "active fire perimeter" we use might be different than the one laypeople expect — while the TV cameras might have moved on from an area because the fire has burned through, we still consider that area "active" until there is a control line around it. Just because there aren't big photogenic flames anymore doesn't mean there isn't still enough residual heat to reignite under the right conditions. NorthBySouthBaranof (talk) 18:08, 15 January 2018 (UTC)[reply]
Nuclear Propulsion Technology (Ships)
How long would it take us to create the infrastructure for nuclear propulsion technology for cargo ships on a massive scale? Please direct me to sources showing why or why not we would be able to achieve this goal within the next 20 years or so. Thanks! HarryOtter (talk) 22:30, 15 January 2018 (UTC)[reply]
(edit conflict)You mean like, ocean-bound cargo ships, but nuclear powered as with aircraft carriers and submarines? Also, do you mean massive scale as in the ships are massive, or the fleet of ships is massive? We have an article Nuclear marine propulsion, that includes a section on civilian use. Experimental nuclear-powered cargo ships have already been built, but it has apparently been repeatedly determined that the infrastructure costs of nuclear power as compared to fossil fuel use are prohibitive, and not offset by how much cheaper uranium is on a per-energy-unit basis. It is also speculated, as described in the article, that a large fleet of nuclear cargo ships could share some of the infrastructure costs and make this less of an issue, but there simply isn't any motivation to do that. Someguy1221 (talk) 22:41, 15 January 2018 (UTC)[reply]
Those are just two vessels. However, the report explains that building merely two vessels will have strategic impact on the entire industrial base. In particular, it impacts things like the total number of nuclear engineers needed in the entire world. Where will you buy your fuel? "I'm sure that in 1985, plutonium is available in every corner drugstore, but in 2018, it's a little hard to come by." For example, did you consider than in 1999, almost all of BWXT's work force was due for retirement? Unless somebody starts getting the young kids to start taking degrees in nuclear engineering, who will design, build, and sell fuel rods to your fleet of ships? (It sure is a bummer that our society pays engineers more money to build software toys than to make nuclear reactors - one of many flaws of a western-style capitalist economy. What smart young whippersnappers are going to want to take on a difficult, high-risk, hazardous, low-transferrible skillset, when they can get paid 500% more money to spread Russian propaganda? Besides, nuclear physics is hard, even if you're ... like, really smart!)
So, unless the Government steps in to ...ahem, "reequilibrate" the invisible free hand of the economy - you know, all Reagan-style, like they did in the 1980s, back when the Government didn't interfere with the economy - our best and brightest just don't want to do the jobs that our world requires to sustain a nuclear-powered economy.
With a twenty year lead time, we could probably train a new cohort of nuclear scientists and engineers... so don't worry, it isn't like we have a twenty-year backlog of crushing the hopes and dreams of aspiring nuclear scientists. We've only been doing that for, um, darn it, thirty years? Man, I'm getting old and crochety!
When we learn to manage stable Nuclear fusion there will be a good chance for broad civil use. Current nuclear technology is to dangerous, regulated and complicated for civil use, with a few exceptions where it has so huge benefit that it makes sense again, like in nuclear medicine, large scale electrical power generation and as capital icebreaker propulsion. --Kharon (talk) 02:34, 16 January 2018 (UTC)[reply]
"Dangerous" my ass -- just compare how many nuclear meltdowns there have been (only THREE so far -- Three Mile Island, Chernobyl and Fukushima, and ONLY Chernobyl caused any loss of life) versus how many refinery fires happen each year, and see for yourself! 2601:646:8E01:7E0B:C81D:59C2:9A63:53DF (talk) 06:01, 16 January 2018 (UTC)[reply]
Three? You mean 20? Nuclear meltdown#Nuclear meltdown events. The meltdown at the military's Stationary Low-Power Reactor Number One (SL-1) in 1961 was the first time a nuclear meltdown proved unambiguously fatal, killing three operators. Generally most people only talk about the meltdown events that breach the containment vessel and spread radiation into the general population, but reactor failures resulting in partial or total meltdown have happened more often than just the three you mention. Dragons flight (talk) 08:06, 16 January 2018 (UTC)[reply]
The biggest problem with nuclear incidents is that Futaba still has a population of zero, just like Chernobyl. It is one thing to have an accident that kills a few people, even a few hundreds of people, but it is something else again to draw a circle around a 24-mile diameter chunk of a country and say nobody can live there any more. Nobody wanted those nuclear cargo ships in their docks -- that was one of the main obstacles to their service. Also, remember the Fukushima disaster was really pretty moderate, only a "level 7 nuclear disaster" or so with multiple reactors leaking. Had they failed to prevent the vast numbers of stored waste fuel rods on site from catching on fire and burning, I'd call it more like a "level 8". (They don't actually have that ... our article International Nuclear Event Scale claims numerically it would be more like 10 or 11 even as it was) Wnt (talk) 16:44, 16 January 2018 (UTC)[reply]
The earth's surface in on the order of hundreds of millions of km2. I'd say a few thousand km2 lost in learning mistakes are vastly preferable to systematically destroying the whole ecosystem. (different IP) 93.136.7.174 (talk) 03:35, 17 January 2018 (UTC)[reply]
Rather than participating in the infighting, here's a link to the MIT Reactor public tours website. Act now! Tours re-open in February. It's one of the largest reactors that you can visit. Be sure to pick up some souvenier alternate-periodic-table-of-the-elements wall posters while you're there, arranged by radiochemistry instead of electron configuration (like this digital copy from BNL). Those posters are hard to find outside of the private collections of the ever-so-small cabal of esoteric nucleon science enthusiasts!
And if you, like I, should have the opportunity to take a ski vacation to the Rockies, don't forget your geiger counter. In all seriousness, pick up (and study) a geology field guide and be careful what you carry home - thar be real radioisotope in them hills! Many rock-collectors have accidentally obtained concentrated uranium in their collections; and while sporadic exposure is probably okay, keeping a source of ionizing radiation in your house leads to all sorts of problems - especially that most invisible foe, carcinogenesis by chronic inhalation and bioconcentration of radiogenic radon. It's never the obvious hazards that get you!
My landlord placed several sources of ionizing radiation in my house, americium to be precise, hidden in plastic containers. He claimed that the state ordered him to do it. He calls them "smoke detectors". -Arch dude (talk) 17:08, 16 January 2018 (UTC)[reply]
It's not a technology issue, rather a security, economic and risk issue. Warships are heavily guarded and overmanned. Container ships are lightly guarded and lightly manned. In general, efficiency for economic reasons tends to move towards less manpower which nuclear does not do at the ship level (even in the Navy, only the largest aircraft carriers are nuclear powered). Economy of scale is limited to propelling a single ship and no shipping vessel will want a crew complement equivalent to the security and engineering on an aircraft carrier. The holy grail of course is batteries with the energy density of fuel oil that could be recharged by nuclear power at a port. --DHeyward (talk) 00:47, 17 January 2018 (UTC)[reply]
Actually the main issue would be general maintenance and regular checks that puts these vessels into the docks for weeks or even months on a regular interval, similar as its done at nuclear powerstations. That is no problem for military vessels or icebreakers, which are expected to come back home frequently or on a seasonal basis.
But cargo ships are generally expected to never stop. Especially the big ones, which would make most sense to equip with nuclear propulsion, need to make their Return on Invested Capital in competition to any other investment. You can not send such a big ship to the docks for one month every year for mentioned and revision while cheaper build big ships in competition, with usual diesel engines, just keep making money. Better fuel economy can not make up the difference. Unless you are the CEO of your privately owned shipping company you will be in huge trouble with all the extra costs. --Kharon (talk) 03:11, 17 January 2018 (UTC)[reply]
Is it possible for a Stirling Single to use anthracite or coke for fuel instead of bituminous (usually Welsh) coal (as was done, although with engines of a very different design, on the Lackawanna line)? How would this affect performance? Would this completely eliminate particulate emissions, or would these still happen at some point (e.g. smoke emissions during starting and acceleration, due to fire-throwing)? 2601:646:8E01:7E0B:C81D:59C2:9A63:53DF (talk) 06:07, 16 January 2018 (UTC)[reply]
Yes, it would be possible. It would work fine on anthracite, as that's what the GNR used to fuel it. This fuel (hard coal from NE England) was used by the GNR, then LNER, and was why they adopted those wide Wootten fireboxes, as are so distinctive on Flying Scotsman today. It's good coal, but it needs a wide fire.
It wouldn't work so well on coke. Coke provides less specific heat by volume, but also has a higher burning temperature on the firebars. If you build a typical fire, you run out of steam. If you build a thicker fire, and force it, you can melt or clinker the firebars. Coke is sometimes used today on preserved lines, because it can be obtained cheaply from old filter beds. Horrid stuff though!
The question of appropriate coal is an important one in the UK. The GWR in particular relied on Welsh steam coal (the world's finest quality coal for this) and designed their fireboxes to be narrow and deep accordingly. One reason why they kept 4-6-0 rather than 4-6-2 Pacifics was that they didn't need to carry such a big heavy firebox. Similarly for the LMS under Stanier (GWR V2.0). In the 1948 Locomotive Exchange Trials, the locos of the different companies were swapped around and compared on local workings. It was found that all the locos of this generation were well designed and performed well, but that firing techniques needed to follow the locomotive and that some coals didn't work well on some locos - mostly the King running on the East Coast line.
UK locos weren't noted for fire throwing. It's too urban a country, with too good a supply of coal, so throwing smoke or sparks was quickly noticed and heavily frowned upon. It did happen during WWII when coal quality fell (small coal), but not in peacetime. The BR Standard classes did have self-cleaning smokeboxes though, which operated by breaking the smokebox char down into small enough pieces to be thrown out through the chimney.
So, by using anthracite, would it be possible to achieve completely smokeless operation (as in, zero visible smoke or soot under all normal driving conditions, even in tunnels and when starting on steep grades) specifically with a Stirling Single? (Or, for that matter, with a Black Five or the Flying Scotsman you mentioned?) 2601:646:8E01:7E0B:C81D:59C2:9A63:53DF (talk) 07:27, 17 January 2018 (UTC)[reply]
Well, what's "normal"? How exceptional is it allowed to get before it's not?
British steam locos, in normal operation during the "golden years" (i.e. not clapped out or wartime austerity) had clean exhaust. This was a legal requirement since the Stephenson era, and meant coal couldn't be used before the 1860s and the development of the firebox brick arch. It was also a pretty carefully enforced rule within companies, and a fireman who couldn't manage it would find themselves carpeted by the inspector. Of course it wasn't perfect. Of course some lines were careless, or just uninterested. But if you look at photos of the period, a well-run loco in a city would have a clean exhaust - at least to the level where any dark smoke was hidden by the steam. Wartime and post-war austerity - different story. Mostly owing to poor coal, even more so than lack of maintenance.
Tunnels, in particular, would require clean exhaust. No footplate crew wants to get kippered. Inclines were avoided in tunnels, for just that reason. Some city station approaches had infamous tunnel gradients, and these often required locos to be in good condition to work them - and it's recorded (particularly for Kings Cross) that a worn loco which couldn't manage this would be rapidly moved off that roster. The UK just didn't go in for those long "rolling coal" hillclimbs beloved of US photographers, or the lignite coals of Eastern Europe where nothing could make it burn cleanly.
One exception to this was around coal mines themselves. The lure of cheap (or even free) small coal meant that these were a lot sootier and ashier. With the gradients of South Wales, you do see some locos making a lot of smoke - but in the Welsh Valleys, few would notice a bit more. Also the prevailing gradients there were mostly downhill. Most Welsh coal came out via the GWR coast route, not northwards and up over the LNWR. Andy Dingley (talk) 10:36, 17 January 2018 (UTC)[reply]
Well, "normal" means a well-maintained locomotive with an experienced crew starting a train of up to maximum rated weight for that locomotive (in case of the Stirling Single, up to 26 lightweight coaches or 6 heavyweight ones), accelerating up to maximum speed (again in the case of the Stirling Single, 85 mph with 6 lightweight coaches or about 60 mph with 26 lightweight coaches), hauling it up and down a 1-in-75 grade (AFAIK the maximum allowed on British mainlines), and then stopping at the next station. With good-quality anthracite fuel, would it be possible to achieve completely smokeless operation (meaning no particulate emissions at all, not just smoke being hidden by the steam)? I.e. if, say, some patriotic passenger decided to wave the Union Jack out the window of the first coach the whole way between stations, would the flag remain clean, or would it get dirty from the cinders and ashes thrown out from the engine's smokestack? 2601:646:8E01:7E0B:C81D:59C2:9A63:53DF (talk) 11:10, 17 January 2018 (UTC)[reply]
There's a difference between throwing out some collectable solids, and visible exhaust. "No particulate emissions at all" just isn't going to happen. After all, where would Brief Encounter be without the odd cinder? If you wave something out of the window, it will collect particles (it has some time to do so, and they're collected). If you look at the smoke, you may yet not see any - there's nothing there visible right at that one moment. Andy Dingley (talk) 00:23, 18 January 2018 (UTC)[reply]
So, just like I thought -- the amount of smoke would be negligible for environmental purposes, yet it would not be entirely smoke-free (so it would be more accurately described as "low-smoke operation" rather than "smoke-free operation"). Is that correct? 2601:646:8E01:7E0B:C81D:59C2:9A63:53DF (talk) 06:05, 18 January 2018 (UTC)[reply]
"Smoke" has changed over the years, as a legal definition. The notion is quite old - Elizabeth I had laws banning the burning of sea coal within London, to stop it. From the beginning of steam locos, they were required "to consume their own smoke". The Lancashire boiler was developed partly to reduce this (by alternate firing of the two flues). Stephenson used two similar flue boilers for his Lancashire Witch. In recent years (I worked on this for big diesels around 1990) we've gained the technical ability to measure smoke automatically, much more sensitively than by eye. Particulate emissions, particularly diesel particulates, are now a huge issue for diesel cars in Europe - to the point when the efficient, modern diesel car might disappear altogether within a couple of years! Andy Dingley (talk) 09:26, 18 January 2018 (UTC)[reply]
Actually, I didn't tell you, but this question had nothing to do with any legalistic folderol -- it was inspired by "Pingy Pongy Pick Up" (a particularly cringe-worthy episode of Thomas & Friends), where near the end they dry out the wet laundry by hanging it on a line behind Emily's smokestack (where it's practically guaranteed to get dirty again from her cinders and ashes!) So this was only a fact-check -- I wanted to double-check whether the laundry would in fact get dirty even if Emily uses anthracite (which it appears would be the case). Anyway, thanks for the info! 2601:646:8E01:7E0B:C81D:59C2:9A63:53DF (talk) 11:24, 18 January 2018 (UTC)[reply]
Thomas the Tank Engine is an excellent series of small books (I have still have mine). There is no TV series. There is certainly no "movie". No such things exist. None at all. Andy Dingley (talk) 14:56, 18 January 2018 (UTC)[reply]
All the Matter in our universe is made of atoms but all these Atoms, which consist of subatomic particles such as electron, neutrons, protons, quarks, gluons etc, do not constitute matter. Right! - WHY? 50.66.1.32 (talk) 06:35, 16 January 2018 (UTC)EEK[reply]
As discussed at matter, there is no universally agreed definition of what it means to be "matter". Historically, "things made from atoms" was one way of describing matter. Another was anything that "has mass and takes up space". Another, more modern definition, is any particle with a "non-zero rest mass". Depending on the definition one chooses, subatomic particles may or may not be a form of "matter". It's complicated, and for the most part not very interesting since it is just a question of how we define our labels. Dragons flight (talk) 07:45, 16 January 2018 (UTC)[reply]
Another functional definition of matter (besides those mentioned above, which are all fine, and perfectly workable) is matter is anything that interacts with the Higgs field. But that's the point, really, defining "matter" is a human problem; its about setting up what kind of categories we decide to organize our experiences, and how to fit things into those categories. The category definitions are purely up to us based on what is most useful to us. If a particular application seems to need us to define matter as "made up of atoms", then we use that definition. If a different application seems to find "has a mass and a volume" as a more useful definition, then we use that one. These are all purely linguistic concerns, and language serves only to be useful to us in communication. Whatever the situation needs, we do that. --Jayron3215:26, 16 January 2018 (UTC)[reply]
They (subatomic particles such as electron, neutrons, protons, quarks, gluons etc,) do have masses but they must be composed of something (which we don’t) but not matter. They have no constituents in simple words.
An atom of a specific element can be distinguished from its atomic number however I have no idea how do these numbers distinguish one element from another and why but since subatomic particles (electrons, protons and neutrons etc.) of all the elements are exactly alike and hence an element is indistinguishable at the individual subatomic particle level therefore an individual subatomic particle say electron can be associated with any atom irrespective of the type of element due to nature of its unknown composition or one can't tell the atoms with which the electron is associated. The same is applied to all the individual subatomic particle.
For Example:If the electron of an Aluminum and Zinc are not made up of Al and Zn respectively then how do we differentiate between the electron of Al and Zn if analyzed separately? Further, At what minimum size of any element say Zn started showing up its physical appearance as a substance of Zn if we zoom out slowly from the nucleus of its any atom. 50.66.1.32 (talk) 05:32, 17 January 2018 (UTC)EEK[reply]
The difference between the electrons does not matter, but we need to count the electrons. Just as you can count the people in identical twins, you can count electrons. Perhaps you could do this by successive ionization, or by observing the energy needed to extract the innermost electron, or by measuring the charge on the nucleus. One atom of zinc will be nothing like the bulk material, it will be more like a gas. Dizinc, Zn2 will have different properties again, and larger clusters will be different again. Different properties will emerge at different numbers of atoms. Density, crystal structure, melting point (when the structure is disorganised) or boiling, when atoms escape from the surface, hardness, strength will all vary depending on the particle size when there are few atoms in the cluster. Graeme Bartlett (talk) 11:36, 17 January 2018 (UTC)[reply]
I'm dimly aware that NSAIDs reduce inflammation, which in turn helps reduce pain.
However, I was of the impression that inflammation was a biological process that aided healing and/or reduced susceptibility to infection. If this is true (I may be totally wrong), it seems plausible that NSAIDs might inhibit healing. Is this true?--Leon (talk) 08:11, 16 January 2018 (UTC)[reply]
There is evidence (often from animal models) that prolonged use of NSAIDs may impair healing from certain kinds of bone, muscle, and connective tissue injuries. [3][4][5] Short-term and low dose use of NSAIDs is usually considered to be of minimal concern. Contrariwise, it is also worth noting that pain management may aid recovery in some circumstances by allowing people to be more active and/or participate in physiotherapy more eagerly, etc. [6] Pain management may also allow a faster return to a normal lifestyle. Finding a balance between beneficial pain management and potential risks is something that needs to be considered on a case-by-case basis. If you have specific concerns about your own treatment, you should consult a doctor. Dragons flight (talk) 08:37, 16 January 2018 (UTC)[reply]
Side note here — you seem to be under the impression that the pain relief from NSAIDs is a result of their anti-inflammatory effect. I don't think that's correct. NSAIDs interfere with the production of prostaglandins, which are part of the causal chain in both inflammation and pain.
Of course, if you bring down inflammation, then you may also prevent pain that would have been caused by that inflammation, but that takes longer. I'm pretty sure the analgesic effect of NSAIDs works faster than that. --Trovatore (talk) 21:05, 16 January 2018 (UTC)[reply]
Actually I'm not sure now. I can't find "prostaglandin" mentioned at either pain or nociception. "Pain" is mentioned at prostaglandin once, in a fairly offhand way, saying that one function is to "sensitize spinal neurons to pain". I don't find anything in the NSAID article that specifically explains the mechanism(s) of analgesia (though there's an intriguing sentence about how acetaminophen (paracetamol), which is not normally considered an NSAID, interferes with COX in the nervous system specifically rather than in the body generally).
So I think there's an opportunity for someone to improve at least three articles (NSAID, prostaglandin, and pain) with some details on the mechanism or mechanisms by which NSAIDs reduce pain. Assuming, of course, that such details are known. Does anyone here know? --Trovatore (talk) 21:53, 16 January 2018 (UTC)[reply]
How long have zoologists known that animals don't have four legs + wings?
I was looking at commons:Category:Obsolete dinosaur restorations for a larf, and this image struck me, but "Proportions and poses are wrong in all the animals" seemed a bit simple, and I noticed that the creature on the far right appears to be (the image is a little blurry) some kind of four-legged, winged "dragon"-type creature. Would an up-to-date scholarly work from Princeton University in 1877 portray such an animal? Or are my eyes just failing me and it's just a pterodactyl in the wrong pose? Either way, I'm kinda curious when scientists figured out about the four legs and wings thing. Hijiri 88 (聖やや) 09:01, 16 January 2018 (UTC)[reply]
I'm not sure I really understand the question. Yes, I think it's a pterosaur of some kind (probably a pterodactyl), but it's probably the only animal on there that's pictured correctly (we have it on all- fours in our size chart at Pterodactylus, for example), though the proportions are a little off. The dinosaurs pictured are much too up-right and their tails should not be all wavy like a cat's. Likewise, the plesiosaur-ish beasties would not have such wavy necks. I'm not quite sure what those two squat aquatic beasties are meant to be. Matt Deres (talk) 15:07, 16 January 2018 (UTC)[reply]
To my eye the limbs seem relatively accurate -- the folded wings appear to have multiple fingers pointing forward, as best as I can see, as pterosaurs did, rather than only a single free thumb as in bats. I don't see four legs. The remarkably rigid groundplan of tetrapods is certainly not something that could have been predicted a priori - for example, the number of legs and wings in various insects is prone to considerable variation, though they don't typically add much to the primitive groundplan but only take away in varying degree (compare Nymphalid butterflies with two wing and two leg pairs, flies with one wing and three leg pairs, and other butterflies with two wing and three leg pairs). Of course, before awareness consolidated of evolutionary and developmental principles, even the framework to assemble such knowledge would not have existed. If the gods want to make a pegasus, why not? Wnt (talk) 16:31, 16 January 2018 (UTC)[reply]
The evolution of the insect body plan is really fascinating. Most extant insects, including all winged insects, are in the subclass pterygota. The ancestral pterygotan is believed to have had an odonatan body plan, with six legs (three pairs) and four independently-articulated wings (two pairs). It's actually more common for a pair to be modified than deleted. Dipterans have evolved the hind pair of wings into halteres, and beetles have evolved the fore pair of wings to serve as protective organs when folded, and balancing organs in flight. How fascinating is it that for hundreds of millions of years, millions of species simply worked on this one body plan with really only marginal changes to it? Really cool! Also, to the original question, I agree with others that the animal on the far right of that picture does not look like a dragon, it looks like its wings are part of its forearms. Someguy1221 (talk) 23:37, 16 January 2018 (UTC)[reply]
As no-one has never found an animal with four legs and also wings, the assumption is that such an animal doers not exist. Logically, however, zoologists still do not "know" that such an animal does not exist - because it is impossible to prove the negative. Wymspen (talk) 17:05, 16 January 2018 (UTC)[reply]
True, but, since the evolution of wings in addition to four legs would provide an evolutionary advantage, and hasn't happened, we can conclude that the most likely reason it hasn't happened is that there is a reason why it doesn't happen. Robert McClenon (talk) 04:45, 17 January 2018 (UTC)[reply]
Some poor animals have been born with six legs instead of four so yes it isn't entirely impossible that for instance a bat like that might arise. Dmcq (talk) 18:22, 16 January 2018 (UTC)[reply]
That's one of the big mysteries though. Lots of people have hexadactyly, and polydactyl cats occur much more commonly in certain breeds, and the fossil record shows polydactyly in early tetrapods before five became the standard ... yet there are no polydactyl species now that I know of! There are a lot of spectacular things like asexual reproduction that can evolve very fast in multiple populations of modern origin ... yet they always lose out in the long term. (Well, except in rotifers...) This gives me a sense that there is a kind of "temporary" evolution where radical variants are selected for in the short term, and can become prevalent under extraordinary conditions (such as artificial selection) yet be utterly doomed on a longer time scale. Indeed, I have a creeping suspicion that there may be a distinction between "stem species" and "terminally differentiated species" that remains to be made. In the case of six-limbed mutant animals though, the point is not so subtle - so far as I know these are almost always freakishly impractical. (Please correct me if I'm wrong; I'm going by recollection) Wnt (talk) 22:35, 17 January 2018 (UTC)[reply]
All Chordates Are Tetrapod
It appears that the chordate body plan is inherently tetrapod. The arthropod body plan, which involves a variable number of segments, each of which can have appendages, is an entirely different scheme. The only vertebrates (and therefore the only chordates) that have evolved the capability of flight paid the price of repurposing their front limbs as wings, rather than evolving wings as additional appendages. There is every reason to believe that the chordate body plan doesn't support a hexapodal anatomy. Of course, the original question was how long this has been known. That is, how long has it been known that the hexapodal vertebrates of folklore, such as winged horses and winged humans, are only found in folklore and not just "not yet found" (cryptids)? Robert McClenon (talk) 04:15, 17 January 2018 (UTC)[reply]
Well, it seems everyone else is seeing the image differently from me. I can see, having read the rest of yer comments, that it probably is not a creature with wings and four other, separate limbs extending from its torso. And I had always thought there was some reason scientists had established why real animals (as opposed to dragons, pegasuses and angels) tend not to have four legs and wings. Granted, I'm a total layman and I heard this fairly recently from another layman (an interview with George R. R. Martin where he explained why the dragons in his A Song of Ice and Fire books do not have four legs like the ones in Dungeons & Dragons). Hijiri 88 (聖やや) 05:23, 17 January 2018 (UTC)[reply]
For the record, I wasn't aware of the two most recent comments when I wrote the above (check my edit summary -- I edited the main heading). I was responding to the discussion as I had read it a few hours earlier. Hijiri 88 (聖やや) 09:15, 17 January 2018 (UTC)[reply]
January 17
Taxonomic History of Mollusca
When were the very diverse Mollusca identified as a phylum? Our article on mollusca identifies them as having been identified in 1758, in the great 1758 edition of Systema Natura, but I further see that Linnaeus had identified the Mollusca as an order in the class Vermes. The phylum, as the highest-level division within the kingdom Animalia or Metazoa, wasn't defined by Linnaeus, only by Haeckel. (Linnaeus defined kingdom, class, order, genus, species. Family also came later.) So my question is when were the Mollusca defined as a distinct phylum? Also, were they always recognized as a distinct phylum? The various classes of molluscs are not obviously related except to a zoologist who is familiar with the mantle and mantle cavity. A clam, a snail, and an octopus certainly don't look alike. I see that Linnaeus evidently did recognize that they were a single taxon (but he saw almost everything). So what is the taxonomic history of the category of Mollusca? Robert McClenon (talk) 04:25, 17 January 2018 (UTC)[reply]
In Pittsburgh today it is 11 degrees F. That's way colder than Boston, Bangor, Ithaca NY, and Burlington today, but it's way farther south. Is it random or does it happen a lot? Thanks. 144.35.45.59 (talk) 04:49, 17 January 2018 (UTC)[reply]
As a general rule, areas close to ocean coasts like Boston, and to a lesser extent, Bangor, Burlington and Ithaca have more moderate temperatures with fewer extremes, than inland areas like Pittsburgh. Ocean waters change temperature very slowly, whereas the land and the air can change temperature much more readily. So, nearby ocean waters act as a buffer to rapid changes in temperature. Please read this for more information. Cullen328Let's discuss it05:06, 17 January 2018 (UTC)[reply]
That is exactly why I said "to a lesser extent". Pittsburgh is roughly twice as far from the Atlantic Ocean than Ithaca is. And individual temperature readings on one day mean very little. If you take a look at historical average temperatures by month in that region, you will find that, in general, inland areas have more extreme variations than coastal areas. Cullen328Let's discuss it05:24, 17 January 2018 (UTC)[reply]
I suspect that when you compare Pittsburgh to Boston, the most salient factor explaining the difference in climate is each city's proximity to the ocean.
I suspect that when you compare Pittsburgh to Ithaca, the most salient factor explaining that difference in climate comes down to prevailing winds.
But in any given instance, we need to get some more details to understand what makes your town colder than the town 200 miles northeast.
... and so on. That's quite compact, and I already know what I think is keeping you below freezing... but I'm heavily trained in interpreting weather, and the Government actually measures how rapidly I can spit back those weather-numbers! To the untrained eye, that number-soup carries very little information! Besides, we're in no hurry now - I've got a lot of spare time to think about weather at the moment!
As an avid enthusiast of the weather, I always start with the prog charts and surface analysis, and then I read the Forecast Discussion. In these special technical weather service products, the chief meteorologist on duty in your area will explain in great detail what they're observing, why they think it's happening, and how their analysis is informed by technology, including computer climate models. It tells you not only what the weather's doing, but why it's doing it, and how we know.
The combined effects of a slow moving upper-level trough, favorable upper jet entrance region dynamics, and a moist S-SW flow over a deep layer, continue to bring light-moderate snow to NEPA and much of CNY this evening. At the same time, there appears to be a bit of a disconnect between the layer of best forced lift and the dendrite growth zone, resulting in fairly small crystals/snowflakes for most locales and accumulation efficiency not quite as good as it could be.
”
And in Pittsburgh:
“
A lowering temperature inversion and decreasing moisture should end this by morning. Maintained current advisories as is for now with the snow ongoing. Otherwise, patchy stratocu with upper troughing and cold advection should affect the area tonight. Lows should be around zero.
More substantial snowfall is expected starting this evening into tonight, as a coastal low pressure system is forecast to emerge off the Delmarva and track northeast along a baroclinic zone close to the NJ/Long Island coast. At the same time, the positive tilt mid/upper level trough will migrate eastward. Appears that a transfer of energy as coastal low jet structure begins to take hold early tomorrow morning will help phase the clipper system. This coastal low track has been key for this forecast as it is projected to track across the Cape and up towards the Maritimes. At the same time, open waveat 700 mb and surface high situated over the Maritimes will help allow the warm air to push into southern New England. The lack of blocking, also allows for this system to be quite progressive.
”
Wow, that's a lot of atmospheric science, delivered straight up from a real actual atmospheric scientist!
When you get into the Forecast Discussions, you start to recognize that the air and atmosphere are a giant system, and when it's cold on the ground in Pittsburgh, it's because Earth's atmosphere is doing something special somewhere else. At this very moment, Pittsburgh is colder than the cities north of it because you're behind the front. Your cold air is too low-pressure to blast into Ithaca; for now, a slug of cold air is trapped near the ground in western Pennsylvania, even though it looks like in the next few days, your cold air is going to ride over the top of their airmass. In the short term, their cloud cover is going to hold in some thermal energy, and they'll soon be mixing in more heat out of the Atlantic over the next few days. But, it's the Northeast - it's really dynamic and anything could change! I spent the first few days of 2018 travelling the Eastern seaboard, convinced that the giant high pressure slug three thousand miles wide was totally impenetrable, and ... whack! A surprise hundred knot high level wind killed our blue skies from totally the opposite direction!
If you love weather, and need more than just the conditions forecast, learn to know and use the Area Forecast Discussion!
It's west of most Appalachiany stuff, not all. I've been there and there's freaking cliffs/near cliffs everywhere. Okay not everywhere but the Greyhound goes through a tunnel through the cliff right outside downtown just to get in and there's many bridges over valleys or inclined rail-like things (see image) from the steep(ish) elevation drops of hundreds of feet impeding metro area connectivity so much. Sagittarian Milky Way (talk) 06:32, 18 January 2018 (UTC)[reply]
I didn't say hundreds of feet of relief was enough to obstruct the weather, I just expected the site to be less hilly and have wider riverplains since it's so west and big. Perhaps Philly had a financial interest to make it bigger while trying to copy the Erie Canal? Perhaps the hilliness was a benefit since it meant nearby fossil fuels for the factories? I wonder if Burlington would've been at least a degree Fahrenheit warmer that day if the gaps in the Appalachians at the Burlington to Montreal and Mohawk River routes didn't exist. Sagittarian Milky Way (talk) 01:39, 19 January 2018 (UTC)[reply]
Is it a contradiction to be a strong Lewis acid (receive electrons) and a strong reducing agent (loses electrons) at the same time? And is it a contradiction to be a strong Lewis base (loses electrons) and a strong oxidizing agent (causes others to lose electrons) at the same time? Can anyone list any molecular examples? Thanks. 12.130.157.65 (talk) 15:33, 17 January 2018 (UTC).[reply]
Various iron(II) compounds are a prototypical example of a metal cation that is in the lower of several common oxidiation states for that metal. It is a fairly good reducing agent, becoming the more stable iron(III) species (see iron(II) sulfate), and it is a Lewis acid because it is cationic with many open coordination sites (notice the many Coordination complex of it; doi:10.1021/cr040664h has many examples of reactions involving Lewis aciditity anddoi:10.1002/cctc.201402029 is an interesting recent example). DMacks (talk) 16:01, 17 January 2018 (UTC)[reply]
Damn, that article dated 1942. I'd trust it if it were in the '70s though. Not even Linus Pauling's book dated 1970 (which a lot of gen chem textbooks base categorizing off) covers this subject? And Linus Pauling has since updated his 1st 1970 book. 12.130.157.65 (talk) 16:42, 20 January 2018 (UTC).[reply]
When I look at the article reducing agent I see I'm more confused than I expected. My impression is that a "true" reducing agent can be written as participating in a half-reaction that releases electrons, while the thing reduced gets only the electrons and nothing else. But our article calls glucose being respired in the presence of oxygen a reducing agent. Now this is relevant to a redox reaction, and the oxygen does get reduced ... but without a clean model for transferring electrons, it does seem to vary from the simplest situation, while you could try to call the oxygen a Lewis acid and the CO2 a Lewis adduct, of a sort ... to be clear, that's not a way I've ever heard it put though. But is there a way to explain why things are put this way, or is it just a habit of speech? Wnt (talk) 13:18, 20 January 2018 (UTC)[reply]
And our article on oxidizing agent defines it as causing others to lose electrons, but doesn't infer it has to receive those electrons, do we assume it does? If not, where do the electrons go. And examples can include bacteria, oxidizers destruct bacteria so causes them to lose electrons. 12.130.157.65 (talk) 16:44, 20 January 2018 (UTC).[reply]
The idea of simply transferring a whole electron from one atom to another, for example:
That does seem like the only way to go with this, so let's test it out: sodium peroxide in water should react Na2O2 + H2O -> H2O2 + 2NaOH. In this scenario Na+ doesn't oxidize/reduce anything, (O2)2- becomes H2O2 with no oxidation/reduction at the oxygen which stays in a -1 oxidation state, H stays at +1 the whole time, O in water/OH- is at -2 the whole time. So there it is not an oxidizing agent but it *is* a Lewis base. Whereas with Na2O2 + CO2 -> Na2CO3 + 1/2 O2, the Na+ is always +1, (O2)2- goes from -1 to 0 oxidation state in O2 and -2 oxidation state in (CO3)2-, C stays at +4... oh shoot, is that even acting as an oxidizing agent at all? If I strike an average O stays at -1 the whole time. I suppose the decomposition of hydrogen peroxide (equivalent to this reaction in water) cannot be a redox reaction. ;) I suppose I actually have to *bleach* something with that (O2)2- so there is no oxygen emitted, and then I can say the oxygen goes from -1 to -2 and the other thing goes more positive. Wnt (talk) 01:46, 22 January 2018 (UTC)[reply]
Besides, decay rates only change noticeably with environment for 7Be (an L-capturer where the captured electrons are also the valence electrons) and some cases where the decay energy is tiny (for example, nuclides in this position cannot undergo internal conversion with the inner electrons, but only on the outer valence electrons). Most fission products and actinides don't fall into either of these groups; actually I am not sure if any do, since fission products are neutron-rich, and electron capturers must perforce by neutron-poor, so you'd mostly have to look for gamma emitters. (Is 99mTc a significant fission product? Its ground state certainly is, but I don't know about the metastable state. If so it would be an example, but note that the decay rate changes produced by such means don't usually even get close to 1%.) Double sharp (talk) 08:23, 18 January 2018 (UTC)[reply]
A Breeder reactor creates less waste because it burns up some of what would otherwise be waste. You might also be interested in the rather strange Quantum Zeno effect which does the opposite - though it is not practical as a way of stoping radioactivity. Dmcq (talk) 23:10, 17 January 2018 (UTC)[reply]
January 18
Coherent or highly monochromatic terahertz
Brain fart corrected in title, sorry
I was looking at a paper about imaging cancer with terahertz that is monochromatic, but I'm not sure how monochromatic:
Measurements were performed using a THz time-domain spectroscopy (THz-TDS) system based on a Ti:sapphire femtosecond oscillator (Synergy; Spectra-Physics) pumped by a 10-W diode laser, Verdi. The laser delivered 10-fs pulses at a wavelength of 800 nm with an 80-MHz repetition rate. The laser beam was separated by a polarizing beam-splitter and turned towards the emitter and the detector separately. The emitter was a p-InAs crystal that utilized the photo-Dember effect, and the laser beam was incident at 78° on the surface of the crystal for high THz intensity51. The THz beam that radiated from the emitter was gathered by a parabolic mirror and focused onto the sample holder by a pair of THz focusing lenses
My assumption is that this generates noncoherent light with a narrow range of frequencies. But I don't see how narrow.
The issue here is that they detect methylated DNA in cancer cells as a little bump, maybe a bit more than a tenth of the total signal present. Most of the signal is from a smooth curve of absorption by ice. The thing I'm getting at is that if they had a tighter range of frequencies, they might get a higher signal if they tune precisely right. I also don't know whether the absorption by ice might break up at a very fine scale, with bands where there is no absorption, if you had truly monochromatic terahertz waves to test with???
Obviously what I want to do is find something only the cancer absorbs and turn it up to MICROWAVE HIGH setting until every last tumor cooks through and through, while normal tissue with just a little methylated DNA gets toasty warm but not damaged. Wnt (talk) 01:24, 18 January 2018 (UTC)[reply]
Looking at graphs in this doi=10.1088/0022-3727/47/37/374002 paper, you only get about one full cycle of the THz radiation, and it drops off exponentially with time on the scale of 1ps. So it is actually hardly monochromatic, and would have a bandwidth of 100s of GHz. This would depend on the duration of the laser pulse. If you could pulse your laser every 2 ps perhaps you could get it as coherent as the pulse rate, but then you would have a near THz generator driving your laser anyway! On the topic of selecting DNA methylation, it is found in all kinds of cells, so perhaps it is not targetable. A vibration of a methyl group in a liquid environment may have a band, but it would not break down into fine lines due to the varying environment of the liquid. Graeme Bartlett (talk) 05:26, 18 January 2018 (UTC)[reply]
So is there any known way to make more monochromatic THz radiation? I would think this should be the hottest topic in weapons work right now (to DNA-identify people from space or displace specific binding factors and cause a different syndrome in every member of the political opposition), but all I want to kill this time is cancer. Wnt (talk) 14:55, 18 January 2018 (UTC)[reply]
I need help finding an artillery gun based on this information.
After taking notice of the success of the Famous French 75, Italy manufactured their own, indigenous design of the artillery piece.
Although it had the same rate of fire as the Canon de 75 modèle 1897, it was more mechanically complex and was not as successful.
Arima (talk) 04:42, 18 January 2018 (UTC)[reply]
Not as well as bodies of water. Also deserts have low precipitation, so often clear skies, thus the optimum for radiative losses.
It's a delusion amongst the flat earth people that "Moonlight radiates cold". Indeed, moonlit rocks are often colder than those which aren't. However the reason is that days are hotter than nights, and so night temperatures depend on how fast things are cooling, not how well they're being heated. An area exposed to clear moonlight is the same area that's losing the most by radiation. Andy Dingley (talk) 09:29, 18 January 2018 (UTC)[reply]
Thank you, Andy. So this is about very clear air above allowing heat to escape, and about lack of moisture within the ground, which holds more heat than dry sand? (I've slept on both sun-baked earth and desert, and wow, that sand and air gets cold.) Anna Frodesiak (talk) 11:22, 18 January 2018 (UTC)[reply]
Yes. We have an article: Radiative cooling. "The exact process by which the earth loses heat is rather more complex than often portrayed..."
Here's a great free textbook on weather: Aviation Weather. I actually like the old version - I keep a link to it on my user-page - the AC 00-6A version - it still has the original cartoons from 1943's Meteorology for Pilots!
If you like math, you can use the Stefan-Boltzmann law to study why deserts get cold. Here's some science from Arizona State University - a world-reknowned center for excellence in both deserts and planetary science: Stefan-Boltzmann law for radiative cooling. In my old planetary science class, we were taught by a radioscientist, so he made sure we corrected for the non-zero cold sink of the cosmic microwave background radiation: on a clear night with no clouds, your desert ground is essentially losing heat to a cold-sink that's only a few kelvins! This is why it is possible to use a clear desert night to produce ice, even if the air temperature is above freezing! If you're really smart, you can make the physicists mad by pretending to violate the second law of thermodynamics, like this Nature letter demonstrates! Hey, I recognize that photograph - I've spent a lot of time on that roof looking skyward!
The theoretical Volumetric heat capacity of Silica (Sand, Sandstone, Glass) is 1.5, of Water 4.18 and of Air 0.0013 J⋅cm³⋅K−1 (Joule per cubic centimeter per temperature difference of 1 Kelvin). So Sand, which always contains some air is not a good material to store heat. Like a battery that can store 1 Kw/h compared to one that stores 4 Kw/h. The volumetric heat capacity of Sand is actually only around 0.8 tho there are many different "mixtures" of minerals called Sand and thus it can be a bit higher or lower. Additionally by definition deserts contain the least amounts of water. Thus a desert is physically less able to store the heat from sunlight and it gets hotter with less "energy efford" aswell as cold faster when the heat disperses. --Kharon (talk) 13:59, 18 January 2018 (UTC)[reply]
It has not been mentioned yet, but the ability to store heat (measured by the heat capacity) is not the same as the ability the regulate the environmental temperature. The specifics depend on a lot of complex phenomena (see convection), but one key variable is thermal conductivity.
Thank you, especially Nimur for the really good pdf. Weather has always mystified me and this is really interesting. And no, anything about maths goes way above my head. :) Anna Frodesiak (talk) 22:10, 18 January 2018 (UTC)[reply]
"Rock holds heat well" hides some complexity. What it's really about is that rock is a good insulator. This means it doesn't exchange heat quickly with its surroundings. This means hot rocks will stay hot for a long time (and, of course, the inverse). That's heat that isn't leaving the rock for its surroundings. Meanwhile, once the Sun goes down, atmospheric heat gets carried away via convection, which occurs rapidly. You probably don't live in an underground burrow, so you lose heat to the atmosphere. --47.157.122.192 (talk) 09:37, 19 January 2018 (UTC)[reply]
I can't find any good references at the moment, but one thing to consider is that "rock holds heat well" really only applies on a per-unit-mass basis. Rock is opaque, solid, and a poor conductor, so only the very surface gets heated by the sun, which in turn means it can loose that heat relatively rapidly once heating stops. In contrast, water is transparent, so solar heating affects a larger volume. Depending on the weather, it can also be physically mixed, transporting surface heat to a greater depth. This means that water bodies have a much larger effective heat capacity than rock, and so take longer to both heat up and cool down. Iapetus (talk) 10:55, 19 January 2018 (UTC)[reply]
Carbon fibre
How much weight can a carbon fibre sheet hold, in:
1) 1 inch thick sheet.
2) 1 feet long stand, filled round stick or non-filled round stick.
Also,
I require a calculating method or so, to calculate weight vs. height, length, filled/non-filled carbon fibre base.
There are enough varieties in construction of such materials that you would need to be much more specific if you want quantitative results.
Typically, material properties can be found from whomever sells such materials. For example, here is one vendor listing, technical data sheets from PlastiComp. You can use standard-form equations from our article on flexural modulus to model the material. Beware that fibers and textiles are not always well-modeled by simple equations! In such a case, you'll need to track down data from an empirical test.
I have recently noticed a significant improvement in the mpg I get from my Fiat Punto Mk2 1.2l 8 valve. In the past I have usually got about 40-45 mpg, but the last two fills I have got 50 mpg. The types of journeys and loads have not changed. What could cause such an improvement? DuncanHill (talk) 19:40, 18 January 2018 (UTC)[reply]
Setting aside that fascination of such minutia is possibly a sign of a mental disorder ; -) It may be that DH lives in the northern hemisphere where it is currently winter. Cold air is denser. Thus the compression ratio is slightly raised thus increasing engine efficiency. 10-20 % seems a lot however. Is this metered fuel from the pump or what appears on the gauge or a mixture of both? As you may be aware, gasoline/petrol and diesel have large coefficient of heat expansion. This is why aircraft are fuelled by weight and not volume. Therefore, volumetric gauges can easily be out by 10-15% over the course of a year. RH can affect MPG as well. Oh, and of course, have you recently inflated the tyres/tires ? That can reduce the rolling friction too. So that dispenses with the most obvious. Back to you to add more info. Aspro (talk) 20:25, 18 January 2018 (UTC)[reply]
Metered from the pump, Northern Hemisphere, no change to tyre pressures. Nothing mentally disordered about noticing that you're saving money! DuncanHill (talk) 20:54, 18 January 2018 (UTC)[reply]
If there's a way to get 11-20% better fuel efficiency from a car (similar to my own), I'd really like to know about it! The only possible factor I can think of in this instance, Duncan, is that it's been somewhat windy in the UK of late – is it possible that by lucky chance your recent journeys have experienced more favourable wind assistance (and less wind resistance) than average? {The poster formerly known as 87.81.230.195} 90.200.41.3 (talk) 00:45, 19 January 2018 (UTC)[reply]
Gasoline is denser at cold temperatures, so you get more kgs per gallon. Add to that that maybe you took an extra motorway trip or avoided some traffic jams (maybe roads were quieter because of holidays), and 10-20% is certainly possible, especeially if you have a 30-40 L tank. — Preceding unsigned comment added by 78.0.222.210 (talk) 02:23, 19 January 2018 (UTC)[reply]
@Aspro:Cold air is denser. Thus the compression ratio is slightly raised thus increasing engine efficiency. - huh? The compression ratio is a geometric factor, and while it may be affected by a few ppm by metal contraction in cold weather, it has little to do with air density. TigraanClick here to contact me10:22, 19 January 2018 (UTC)[reply]
Gasoline is indeed denser in winter, but it does not explain everything. The CTE is about 0.1% per °C, so assuming a 30°C swing between summer and winter temperature, that explains 3%. Significant, but certainly not "10-15%" (that would require a 100-150°C swing, which no place on Earth has ever seen[citation needed]). TigraanClick here to contact me10:28, 19 January 2018 (UTC)[reply]
Thanks for all the suggestions. I haven't noticed similar improvements in previous winters. Indeed, if memory serves, cold damp weather in the past has led to an increase in consumption which I have put down to it being a bugger to start and misfiring until it warms up (if it passes the next MOT I might buy it new coils and HT leads as a treat). Hmm. I think my last couple of long-distance trips were smoother than usual - there's a new bit of dual carriageway over the moors, that would help. And it's possible my driving habits have improved. It's just rather disconcerting to get such a major improvement on an old car - was worried it might be a sign of impending doom! DuncanHill (talk) 14:36, 19 January 2018 (UTC)[reply]
The way to mitigate miss firing is to treat yourself to a 'sports' coil and new HT now ! For Italian's are cheap skates and just deliver cars at the lowest possible price. Then spray the HT over with 'damp start' to seal out the moister. Cost-wise this will pay for the outlay. Another is to use a sump heater such as [11]. They use so little paraffin/kerosene per week that the running cost is negligible. Throw an old woollen blanket over the bonnet/hood, as the engine is a big block of metal and acts as a thermal store, so capitalize on it. Finally, don't forget the battery/accumulator. Short runs in cold weather may lead them to sulfate up – requiring a not cheap replacement. Make sure the terminals are clean and there is good electrical contact. Silicon grease is better than Vaseline in this respect and a hydrometer will indicate the condition of your battery so you can take proactive active measures before problems surface. Also, water thermostats. It should not open until the engine is up to running temperature. But if it is tired, it may not be closing properly to start with – so replace it. Some people when they start off on a cold winters morn, scrap off the ice on their widows whilst have their cars running on full choke and with the heater on full blast. Again, it is chilling the engine before it has chance to warm up and doesn’t 'pull' properly until several miles down the road. Aspro (talk) 19:41, 19 January 2018 (UTC)[reply]
Sealed battery (haven't seen an unsealed one for years). No choke (haven't seen one of those for years either). And I doubt the police would look kindly on someone leaving lit paraffin heaters under cars in the street (and where would I put it once I had driven off?), and I'm sure my insurers would have kittens! I do know not to run the heater until it's warmed up. A blanket over the bonnet would either blow away or get nicked. DuncanHill (talk) 17:35, 20 January 2018 (UTC)[reply]
Mileage taken from trip meter, fuel volume taken from the pump. And I can see that the gauge is going down less for a given journey now. DuncanHill (talk) 17:35, 20 January 2018 (UTC)[reply]
Physics Question (one more)
Are the standard sizes and masses of a proton, neutron, electron etc. are naturally selected and why do they not change over time?
Similarly, nature has the ability of random selection too, therefore, we can't neglect completely the chances of varying masses of subatomic particles instead of standard as a proton is approx. 1850 times’ massive/heavier than an electron so it means the chances of the diversity in the masses of subatomic particles in the random selection are more than the chances of the standard masses of subatomic particles. Please disregard if not interested 50.66.1.32 (talk) 21:04, 18 January 2018 (UTC)EEK[reply]
Natural selection in the usual scientific sense requires the populations of entities being selected producing similar but not identical progeny with slightly varying characteristics due to occasional errors in the functioning of a genetic code. Since particular kinds of subatomic particles do not have a genetic code (or any analogue to it) and do not reproduce their own kind (though they can give rise to different kinds by decaying or combining) the concept is not applicable. The OP's second sentence ("Similarly [. . .] particles.") does not appear to be meaningful English in any of its clauses. {The poster formerly known as 87.81.230.195} 90.200.41.3 (talk) 00:41, 19 January 2018 (UTC)[reply]
Another possibility is that Big Bang(s) that reach 2018* tech are unlikely to end before Big Bang-causing tech makes Big Bang(s) that reach 2018* tech and are unlikely to end before Big Bang-causing tech makes Big Bang(s) that reach 2018* tech and are unlikely to end before Big Bang-causing tech makes Big Bang(s) that.. Thus if humanity doesn't want reality itself to be something a pimply alien made one science class or a quantum of hyperdrive exhaust it can help by not inventing universe-causing technology or non-human(s) that might invent it. *increment number by 1 each year. Sagittarian Milky Way (talk) 08:31, 19 January 2018 (UTC)[reply]
The anthropic principle seems like it may be baked in to the idea of "collapsing the state-vector", at least under some face-value versions of the Copenhagen interpretation. An electron does not pass through one slit or the other unless/until you observe it. Does this mean that the positions of all the stars in the cosmos were a blur until the First Man looked up and saw them? For that matter, were they a blur until the Last Man saw them, and the other Men before him were part of that collapse of probabilities? Is there something special about some past, present, or future consciousness of person that makes it better positioned to be the one to perceive a state that allows Him/Her/Itself to exist? What if the seventh seal is the distinction between the past and the future? Wnt (talk) 20:43, 19 January 2018 (UTC)[reply]
If you put Schrodinger's Cat box in an anechoic room, leave a microphone that can hear cat heartbeats at its distance from the box in the room before you leave and have it send the reading to you over wifi to a phone with a bushel over it do you think the screen is both cat organ noise and no cat organ noise till a human looks?Sagittarian Milky Way (talk) 22:50, 19 January 2018 (UTC)[reply]
Well, inside the box, there's no cat's meow without a live cat. Outside the box, it doesn't matter if you look by light or by a wi-fi transmission ... I think. Wnt (talk) 01:27, 20 January 2018 (UTC)[reply]
Hi. The word "cryogel" appears in various WP articles but doesn't have its own article or redirect. There's also no Wiktionary entry, and I ask as someone who works on Wiktionary. Could someone give us a quick but clear definition we can use, that distinguishes a cryogel from other things (gel, aerogel, xerogel, whatever)? Thanks! Equinox◑06:56, 19 January 2018 (UTC)[reply]
I can't seem to find an explicit definition of the word, but the various things I find that are referred to as "cryogels" have in common that they are made by first dissolving something in a solvent, and then freezing and thawing until it polymerizes. Someguy1221 (talk) 07:19, 19 January 2018 (UTC)[reply]
Cryogel seems to be a registered trademark. What would be the inclusive uncapitalised term? I suppose the word might enter the language as a normal term like hoover and vaseline. Dbfirs08:12, 19 January 2018 (UTC)[reply]
This is the website of the company which manufactures it, with plenty of details [12]. Here is a definition from a technical glossary [13] which might be a basis if you wanted to write something, but that is Russian, and elsewhere there might be trademark issues. Wymspen (talk) 10:11, 19 January 2018 (UTC)[reply]
Thanks for the feedback! So I gather it might be a trademark. But if ya look at Google Books [https://www.google.co.uk/search?q="cryogels"+the&btnG=Search+Books&tbm=bks&tbo=1&gws_rd=cr&dcr=0&ei=FcZhWo34AcbbgAbirqeQDQ] you can see a lot of apparently generic talk about "cryogels". The plural and lack of caps suggests maybe the writers often see it as a generic term. Equinox◑10:20, 19 January 2018 (UTC)[reply]
Found a review of the biological applications[1], which describes them as "macroporous gels produced at subzero temperatures (known as cryogels)". Klbrain (talk) 00:55, 20 January 2018 (UTC)[reply]
References
^Plieva, FM; Galaev, IY; Noppe, W; Mattiasson, B (November 2008). "Cryogel applications in microbiology". Trends in microbiology. 16 (11): 543–51. doi:10.1016/j.tim.2008.08.005. PMID18835715.
Current uses of radium-226
Does anyone actually still use radium-226 for anything? (That's the most stable isotope, which used to be the common one used; I know 223Ra is used as a radiopharmaceutical). The sources in our radium article on current uses are from last decade, and even then those uses were being supplanted: we usually use other isotopes (e.g. 192Ir, 60Co) for industrial radiography instead, and we usually use actinides (Pu, Am, Cf) for neutron sources instead of Ra. Is the main use of 226Ra really just to get rid of it by transmutation to 227Ac, like Ullmann's Encyclopaedia said in 1993? Double sharp (talk) 13:01, 19 January 2018 (UTC)[reply]
That's interesting, though I'd like to see where they got that information from. At first glance it seems to me a bit overdoing it to produce pure Ra specifically to get Rn: you can get Rn from anything above it in its decay chain quite easily (it's a gas, while its parents aren't, so the separation is trivial), so isn't a chunk of uranium ore already a serviceable radon source? Double sharp (talk) 13:49, 19 January 2018 (UTC)[reply]
The First and the Last Noon of the solar year don’t coincide. This means solar noon lags 24 hours, which appears in what we call leap year. Although we update our calendar every after 4 years for our own conveniences, however, it doesn’t mean an earth also adjust its axial and orbital motion for the sake of our calendar. This small change reverses days into nights and seasons as well (summer into winter after 720 years approx.) over time, if the real position of the earth is observed in its orbit around the sun instead of adding Feb 29 in leap years. Your comments, please. 50.66.1.32 (talk) 19:54, 20 January 2018 (UTC)EEK[reply]
We adjust our clocks and calendar to match the observed rotation of the earth. Much calculation over the centuries has ensured that our day and year never deviate far from the norm. If we are still around to observe, the day length (via leap seconds or hours) and the calendar (via leap years) will be adjusted as required over the next few thousand years to closely match the exact periods of rotation. Dbfirs21:49, 20 January 2018 (UTC)[reply]
I sort of doubt that prediction, actually. Leap seconds were a mistake from the start. They cause continuing annoyances in the computer age because they make it impossible to match a civil time in the future with a timestamp based on count of seconds. They were never necessary; the drift in (say) the civil time of sunset is slow enough that no one would be disturbed by it over the course of even a long life.
My counter-prediction is that leap seconds will eventually be dumped in favor of some version of TAI or GPS time, possibly with a constant offset to avoid a discontinuity at the time of changeover. There have been several attempts to do this; the last one, if I recall correctly, didn't miss by much. There's a lot of resistance to such a change, of course, but hopefully it will eventually happen. --Trovatore (talk) 21:59, 20 January 2018 (UTC)[reply]
I was looking ahead to a possible further slowing in the axial rotation (not that I'm predicting it -- we just don't know). If leap seconds are abandoned then the alternative is an eventual leap hour that I mentioned above. This would easily be implemented by those countries who have summer time or daylight saving time. We seldom notice that the sun is not exactly overhead when we expect it to be, but eventually an adjustment might be needed to avoid hot sun at midnight. I suppose, by the time it is needed, we might have the technology to speed up the rotation of the earth to match atomic time. Dbfirs08:51, 21 January 2018 (UTC)[reply]
Were there any cases when a TGV train had to stop on a steep grade for some reason (the steepest grade on the Paris-Marseilles line is a whoppin' 3.5%!) and then couldn't get moving again unassisted? Or is the TGV powerful enough that this cannot happen? 2601:646:8E01:7E0B:C81D:59C2:9A63:53DF (talk) 07:00, 21 January 2018 (UTC)[reply]
It's an electric loco, not a diesel-electric (or turbine-electric). So the limit is almost always the torque available from the traction motors, not the total power of the prime mover - for a TGV at least. The TGV isn't designed for slow speed haulage, but it does have sufficient surplus, and at low speeds, to be able to do this. Also the Sud-Est sets have 12 powered axles per set, not just 8, as there's a powered bogie on the adjoining passenger carriage, not just the power cars.
I don't know what you mean by "a whoppin' 3.5%", but for railways that's (1 in 28) very steep for any main line.
This also brings in the issue of rated speed, the lowest speed from which full power is usable - usually limited by the torque capacity at low speeds. Diesel-electrics have often been restricted here (as your question implies - railway traction motors do not have particularly high torque and their power rating is severely restricted at low speeds.). Diesel-hydraulics have better ability to use their power as low speed torque. Andy Dingley (talk) 10:49, 21 January 2018 (UTC)[reply]
Since we're talking about the original line, let's look at the SNCF TGV Sud-Est trainsets. The spec sheet linked from that article gives the mass of the trainset as 385 t. Multiplying by 9.80665 m/s², its weight is 3775 kN, and 3.5% of that is 132 kN. The force/speed graphs at the bottom of page 3 show a force of 210 kN available at low speed: more than enough to get moving on a 3.5% grade, provided only that the wheels do not slip. --70.29.13.251 (talk) 20:13, 21 January 2018 (UTC)[reply]
What is the source of this "chapter 43" that found in a lot of sites on the internet?
I've got this document about "Antihyperlipidemic Drugs" which is "chapter 43". It is found in a lot of sites (such here), but the issue is that as much as I looked for the name of the book that it came from, I couldn't find it. What is the name of the book that it was taken from? 2A02:ED0:6F4E:6D00:F198:54F3:E7C4:F74B (talk) 15:34, 21 January 2018 (UTC)[reply]
It is:
Roach, Sally S. (2004). Introductory Clinical Pharmacology (7th ed.). Lippincott Williams & Wilkins. ISBN978-0006262367.
Any spaceship prototype based on capturing dust and using it as propulsor?
Could a spaceship be based on the capture of matter found in outer space - like dust and asteroids - and posterior use a propulsor? As least, could a satellite use this matter to correct its trajectory? --Hofhof (talk) 22:44, 21 January 2018 (UTC)[reply]
People in the past took a chemical called dinitrophenol to raise basal metabolism but it has a narrow therapeutic index and a propensity to cause cataracts, particularly in women. Pyrogens are a type of chemical which includes some proteins made by immune cells which raise body temperature to fight an infection. Could small amounts of a suitable pyrogen have a similar effect to DNP? Would the therepeutic index be just as narrow and dangerous as DNP? --129.215.47.59 (talk) 14:49, 22 January 2018 (UTC)[reply]
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