Wikipedia:Reference desk/Archives/Science/2018 January 16

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January 16

Stirling single

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)

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.

The leading work here was the Gas Producer Combustion System, based on the work of L.D. Porta and later David Wardale. This allowed low quality small coal, usually of the higher chemical grades, to be burned more efficiently (it wasn't much use for coke). This was adopted by the NCB as it allowed them to burn waste coal from the pithead. However the development of pulverised fuel for power stations gave a better market for that. Andy Dingley (talk) 14:04, 16 January 2018 (UTC)

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)

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)

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)

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)

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)

"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)

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)

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)

Why not? The TV series is actually pretty good for the most part -- it's only seasons 10 through 16 inclusively which don't exist, and the episode I mentioned happens to be one of the non-existent ones!  :-) 2601:646:8E01:7E0B:C81D:59C2:9A63:53DF (talk) 08:05, 20 January 2018 (UTC)

Physics Question

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

What gave you the idea that atoms don't constitute matter? They have mass and volume, don't they? Double sharp (talk) 07:33, 16 January 2018 (UTC)

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)

(e/c) You nearly answered your own question. Subatomic "particles" (which might be somewhat of a misnomer) are constituent to atoms; atoms are matter. Bricks and mortar are constituent to buildings, but do not constitute buildings. —107.15.152.93 (talk) 07:53, 16 January 2018 (UTC)

Yeah, except as noted, there is non-atomic matter. See Degenerate matter, etc. --Jayron32 13:32, 16 January 2018 (UTC)

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. --Jayron32 15:26, 16 January 2018 (UTC)

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

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)

References for those that care: https://doi.org/10.1080/08927020412331332749 and https://www.researchgate.net/publication/236942217_Zinc_nano-cluster_investigated_by_molecular_dynamic_simulations where you can find out for small clusters zinc will form an icosahedron, but with enough atoms it will have hexagonal close packed structure as in the metal. Graeme Bartlett (talk) 11:46, 17 January 2018 (UTC)

NSAIDs

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)

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. [1][2][3] 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. [4] 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)

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)

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)

The details are not really well known, prostaglandins do sensitize nociception (see http://www.sciencedirect.com/science/article/pii/030439409190444X?via%3Dihub) so at least some of NSAIDs analgeisc properties are due to COX inhibition. Some NSAIDs also inhibit the lipoxygenase pathway which is involved in inflammation and sensitizing nociceptors. This paper goes into more detail on possible mechanisms http://dx.doi.org/10.2165/00003495-199600525-00004 2600:1700:A460:5060:9C44:6B42:8646:43CF (talk) 06:28, 19 January 2018 (UTC)

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)

This one does. But it depends on how one defines "wings". —107.15.152.93 (talk) 09:20, 16 January 2018 (UTC)

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)

Further to the pterosaur on all fours reconstruction, see this image of Dimorphodon Matt Deres (talk) 16:55, 16 January 2018 (UTC):

Reconstructed skeleton, Rainbow Forest Museum

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)

Since it hasn't happened with vertebrates, I think that if the gods made a pegasus, they would demonstrating that they were gods. Robert McClenon (talk) 04:45, 17 January 2018 (UTC)

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)

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)

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)

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)

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)

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)

Sharovipteryx is a chordate which repurposed its hind legs as wings!-gadfium 08:26, 17 January 2018 (UTC)

All tetrapods are chordates, but not all chordates are tetrapods. Good luck finding the four legs on a sea squirt or an acorn worm! Wnt (talk) 22:41, 17 January 2018 (UTC)

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)

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)