:OK, I've done a back-of-the-envelope calculation. Assume the boiler+firebox is a cilinder, 10 m long, 2 m diameter, excluding the smokebox. That gives a surface area around 65 m<sup>2</sup>. With an insulation 15 cm think with thermal conductivity of 0.04 W/(m·K) and a temperature difference around 140 K, you loose about 2.5 kW of heat. Burning 1 kg of coal gives about 34 MJ of energy, a bit less if the coal is wet, and at least 5 MJ of that will leave the chimney as smoke, so let's say you get 25 MJ/kg burning coal. Conclusion: if you disable all steam-powered appliances and only have to counter heat loss through the walls of the boiler, you need less than kilogramme of coal per hour. With several tonnes of it in the tender, you can hold out for ages. I wouldn't be surprised if the insulation is actually thinner, given that this is such a minor heat loss. The limit will be your ability to prevent the water in your tender from freezing. Has the tender been equipped with tender water heating?
:OK, I've done a back-of-the-envelope calculation. Assume the boiler+firebox is a cilinder, 10 m long, 2 m diameter, excluding the smokebox. That gives a surface area around 65 m<sup>2</sup>. With an insulation 15 cm think with thermal conductivity of 0.04 W/(m·K) and a temperature difference around 140 K, you loose about 2.5 kW of heat. Burning 1 kg of coal gives about 34 MJ of energy, a bit less if the coal is wet, and at least 5 MJ of that will leave the chimney as smoke, so let's say you get 25 MJ/kg burning coal. Conclusion: if you disable all steam-powered appliances and only have to counter heat loss through the walls of the boiler, you need less than kilogramme of coal per hour. With several tonnes of it in the tender, you can hold out for ages. I wouldn't be surprised if the insulation is actually thinner, given that this is such a minor heat loss. The limit will be your ability to prevent the water in your tender from freezing. Has the tender been equipped with tender water heating?
:BTW, such big passenger locomotives were very rare in western Europe, where almost all steam locomotives were manually fired until the most demanding lines switched to electric traction in the interbellum. In eastern Europe, steam was used longer and in America, everything is bigger (as we say in Europe). [[User:PiusImpavidus|PiusImpavidus]] ([[User talk:PiusImpavidus|talk]]) 16:56, 24 May 2023 (UTC)
:BTW, such big passenger locomotives were very rare in western Europe, where almost all steam locomotives were manually fired until the most demanding lines switched to electric traction in the interbellum. In eastern Europe, steam was used longer and in America, everything is bigger (as we say in Europe). [[User:PiusImpavidus|PiusImpavidus]] ([[User talk:PiusImpavidus|talk]]) 16:56, 24 May 2023 (UTC)
::OK, so I guess we can safely call conductive losses negligible! However, shutting down '''all''' steam-powered appliances would '''not''' be an option in this scenario -- at the very least you need to run the [[mechanical stoker]] to keep the fire burning, and (at least occasionally) the [[injector]] to keep the boiler topped off, plus the blower to maintain a draft on the fire in the absence of exhaust steam from the cylinders! Plus, you would probably want to run the train heat so as not to make things miserable (or possibly outright deadly in the case of the Trans-Siberian) for the passengers, the [[dynamo]] (also for the sake of the passengers, as well as for safety at night and for any communications with the outside), the tender water heating to keep the water from freezing (and to melt the snow if that is to be used as a water supply) and the brake pump (which '''might''' be going at full blast if the train had been stopped by a passenger pulling the cord -- one possible scenario being that a passenger stopped the train because he/she had witnessed a murder aboard, and the train cannot be moved again because the killer had thrown some of the evidence outside so the murder has to be solved first). So, how much energy would it take to keep these things going? [[Special:Contributions/73.162.86.152|73.162.86.152]] ([[User talk:73.162.86.152|talk]]) 03:39, 25 May 2023 (UTC)
== Garden plants' lifespan ? ==
== Garden plants' lifespan ? ==
Revision as of 03:39, 25 May 2023
Welcome to the science section of the Wikipedia reference desk.
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.
What are the approaches or methods of conventional medicine (not specialties, rather treatment approaches or practical methods)?
From all my reading through the years, I came to the conclusion that we can generalize that there are only three approaches or methods in conventional medicine:
Concentrational treatments: Administering a concentration of a molecule / several molecules or of a food / several foods in an internal or external way (ointments, suppositories, drops, shots, etc.).
Surgical treatments: manually removing, altering or adding organs, tissues or secretions
Genetic treatments
Is this generalization correct?
By asking this, I assume that there are tens of specialties in conventional medicine (internal medicine, plastic surgery, psychiatry, otolaryngology, cardiology etc.) but only three approaches or methods shared by them all.
Psychotherapy might also be a method reserved solely to psychiatry, but I'd argue that's more of an exception than the norm.
I think that after replies by User:Graeme Bartlett and User:Lambiam my original question should have been "What does a conventional physician normally do?".
Wouldn't then the answer be the original three types of actions plus wound dressing (which in a broader sense includes Casts) as well as Artificial ventilation?
Most hypnotherapists and psychotherapists will disagree with the last statement. If the question is, "What does a conventional physician normally do?", you can scratch out genetic treatments. It is rather a stretch to classify artificial ventilation as a form of wound dressing, since there is no wound and wound dressings are passive, whereas artificial ventilation is an active intervention. --Lambiam18:59, 18 May 2023 (UTC)[reply]
Yes, sorry, I overlooked the closing bracket after "Casts". I am not sure how to determine the scope of the procedures "normally" done by "conventional" physicians. Are you excluding radiotherapy because radiologists are unconventional? --Lambiam05:06, 19 May 2023 (UTC)[reply]
You may have a decent scientific understanding of basic astronomy, but most people don't. They will believe a message received from a friend that tomorrow Mars will appear as large in the sky as the Moon and will readily forward it to others. Look how many flat Earthers there are, even though their model is flat out incompatible with easily observable facts.
Most people are susceptible to belief perseverance. Combine this with a distrust of the seeming certainty of scientists, a distrust sustained by failure to comprehend the essence of the scientific method.
The idea that heavenly bodies exert influence on us Earth-bound mortals is not a priori wrong. The main issue with popular astrology, such as in the form of a column in a newspaper, is the unverifiability. Compare various divining practices, as well as the popular "colour personality tests": the statements are so vague that half the time they may seem to apply. With the more heavy type of astrology, involving the computation of ascendants and the drawing of charts, some researchers have actually taken the effort to test the validity, but found no significant results.
@Lambiam:: Re your #2 – a lot of the time people don't listen to scientific discussion, only to journalists' interpretation thereof. Occasionally the reports are fair from a knowledgeable journalist but often they are being interpreted by someone with an arts or languages background who last did science at age 16. Couple this with the desire of some editors to hit the headlines with a "shock-horror" or "Gee-whizz" front page story and it's hardly surprising that "the man on the Clapham omnibus" regards astrologers as more reliable. Martin of Sheffield (talk) 21:48, 18 May 2023 (UTC)[reply]
I suspect that a lot of people indulge in astrology as a form of play, without really believing in it. Also, what many people think of as astrology is the grossly simplified Sun sign astrology that was, I believe, invented after 1900 by newspapers to be able to run something readers would want to read every day.
The far more complex Natal astrology requires significant astronomically related expertise – Johannes Kepler made much of his living by being paid for performing it by members of the ruling classes, which may really have depended on his intelligence and grasp of current affairs enabling him to analyse events and offer sage advice. It may even be genuinely useful, not because personal events on Earth are dictated by the minutiae of celestial positions, but because contemplation of the recursively complicated interplay of its supposed influences can free the subconscious to come up with intuitive insights, as may also be the case with the I Ching, Tarot divination, or for that matter Philip Pullman's fictional alethiometry. {The poster formerly known as 87.81.230.195} 90.199.210.77 (talk) 23:30, 18 May 2023 (UTC)[reply]
Thanks a lot for your interesting insights. But that leads me to an even bigger question: why does astrology is now can be considered as an entertainment form and not other pseudosciences? Maybe because the planets and stars do not have a real impact on our society yet? CactiStaccingCrane (talk) 10:49, 19 May 2023 (UTC)[reply]
I never said that. The unhelpful part of your answer was unrelated to the word "boobs". Also, this is the reference desk, not the "make political insults" desk. You're not wrong in a factual sense, you're only wrong in a behavioral sense, which is to say that this is not the place to say things like what you said. Go say them somewhere else. If you have relevant pointers to references someone could read, fine. --Jayron3212:27, 19 May 2023 (UTC)[reply]
Barney: "You're a boob, Gomer!" Gomer: "Andy, he keeps callin' me names!"
I would guess it is part of an ancient drive built into our species by evolution - which favors the species over the individual. Randomness leads to an exploration of the boundaries of what's possible, it also can be used so there is less competition where the whole is divided into twelve groups, and in war it stops the enemy being able to predict what acions. Following something random is the basis of leadership rather than everybody arguing over what to do. Overall I think it may be silly for the individual but its effects have probably been very important for the development of the species. NadVolum (talk) 12:07, 19 May 2023 (UTC)[reply]
Not a good argument: traits that increase the fitness of individuals will spread within a species, even if as a consequence they drive the species extinct. It is doubtful whether "species selection" is of any real importance but it could have some influence only on selecting properties of the species (e.g. propensity to speciate) rather than of the individual. JMCHutchinson (talk) 06:44, 22 May 2023 (UTC)[reply]
Certainly Group selection has a bad press, and it does seem that a characteristic that just favors the group like alturism cannot normally take over completely. However it can reach a game theory type balance or predator prey type swing where some individuals are cheaters. Religion and alturism are backed up by social opprobrium for outsiders or cheaters, The costs of astrology are pretty low but it does have a small in-group mechanism with people asking each other their star sign. NadVolum (talk) 09:07, 22 May 2023 (UTC)[reply]
Astrology, when taken seriously, becomes a religion. In the Old Farmer's Almanac there is always a section on astrology, with the disclaimer that it's for "entertainment". Kind of like professional wrestling. ←Baseball BugsWhat's up, Doc?carrots→ 13:47, 19 May 2023 (UTC)[reply]
May 19
Moss growth and ant hills
I find the traditional explanation for moss growth on the northern part of trees somewhat puzzling. Is the air and bark temperature difference between a northern and all other parts of a tree that big? I suspect it to be within fractions of a Celsius degree at most, if not identical which doesn't seem to be enough to make a difference. Same for humidity. The distance difference in such cases is typically between several to several tens of centimeters.
A similar explanation for ant hills on the southern side also puzzles me. If the sun rises at the east, setting at the west, it would be the eastern side that receives most sunlight, being effectively more warmer rather than southern side. A southern side appears to be roughly perpendicular to most sunrays and thus less insolated than the eastern side. Thanks. 212.180.235.46 (talk) 21:12, 19 May 2023 (UTC)[reply]
May I suggest you do a little experimentwhen the sun is shining.Try going behind a tree hidden from the sun, and then in front of the tree in the snlight and see how difficult it is or not to detect this fraction of a degree you talk about. Ants favor the south east a bit more because they need to warm up in the morning and don't need the heat so much later. NadVolum (talk) 21:55, 19 May 2023 (UTC)[reply]
The Moss article explains why moss likes north sides of trees and shady, moister areas. As for sun angles otherwise, I can tell you from working in glass buildings (which are sort of like corporate anthills) that the sides facing the western sun tend to get hotter during the day, while the sides facing the eastern sun slowly level out as the day goes on. ←Baseball BugsWhat's up, Doc?carrots→ 22:53, 19 May 2023 (UTC)[reply]
Quite right, I stand corrected; although I suspect that moss growing on the northern side of trees is not an observable phenomenon in the tropics. Alansplodge (talk) 11:14, 20 May 2023 (UTC)[reply]
May 20
Chimpanzee groups fight each other
I read in Frans de Waal book that two groups of chimpanzees sometimes fight each other. Is it true that two groups of chimpanzees sometimes fight each other, with one group attacking individuals? So a group of male chimpanzees attacks single chimpanzees. 2A02:908:424:9D60:979:D36A:5559:FF19 (talk) 19:24, 20 May 2023 (UTC)[reply]
There are researchers at The Lepidopterists' Society who may be contacted about the question. On this website Judith Willson writes: "Insect wings don’t grow back or heal, and a moth with a broken wing is never going to recover. If the moth is otherwise uninjured, you can look after it though. All the moth needs is somewhere quiet and safe, something to eat and something to rest on. Moths don’t live very long anyway, but you can provide it with a nice life for the time it does have left." Philvoids (talk) 12:52, 21 May 2023 (UTC)[reply]
I saw a video not that long ago of a butterfly's wing being repaired with a prosthesis by microsurgery. --Lambiam09:56, 22 May 2023 (UTC)[reply]
It seems that the originally correct article on the Downs cell has been corrupted from claiming that sodium is produced to that magnesium is produced. When web-searching for Downs cell I cannot find anything that supports this statement, but I'm not a chemist, so this needs to be resolved by a chemist. Rursus dixit. (mbork3!) 16:37, 21 May 2023 (UTC)[reply]
Use of the Down's cell in electrolysis of molten sodium chloride to produce sodium metal and chlorine gas is attested here. Processes for electrolytic production of magnesium are documented, [1] but none of these involve Down's cells (magnesium is mainly produced in China via the energy-intensive pyrometallurgical Pidgeon process). A one day effort on 29.11.2019 by User 118.137.73.73 to edit sodium out and magnesium in as a "factual error....fixed (thanks to me)" seems entirely mistaken and I agree with Rursus that those edits should all be reverted. Philvoids (talk) 17:36, 21 May 2023 (UTC)[reply]
For the purposes of a fictional historical narrative I have in mind —
Suppose a small pacifist European nation in the later 17th century were to come into possession of a very large quantity of gunpowder (they've just defeated an attempted invasion and captured all the enemy's armaments), how could they best dispose of it usefully, given that:
they don't need it for armaments themselves (they have effective other means – don't ask);
they don't want to sell it to other nations (who might use it in warfare);
they use little or none for construction and quarrying;
they already have enough for fireworks, etc.
(Yes, I have read Gunpowder, and to anticipate a sidetrack, they can re-use the metals, wood, etc. of the captured armaments for domestic purposes.)
Repeated soaking and filtering would remove the KNO3 which could be used as a fertiliser. The residue would be a sulphur/charcoal mix which is non-explosive. Martin of Sheffield (talk) 19:02, 21 May 2023 (UTC)[reply]
Thanks for the responses (so far). I should perhaps have emphasised that only a 17th-century knowledge base is available to them: I was wondering if just sprinkling the gunpowder lightly on tilled fields or pasture would be viable. I doubt if explosiveness would be a factor after the first rain shower. {The poster formerly known as 87.81.230.195} 90.199.210.77 (talk) 21:12, 21 May 2023 (UTC)[reply]
Some online sources state this will work just fine, but these are not reliable sources in the Wikipedia sense. Thinly sprinkled gunpowder is probably not dangerously explosive anyway. --Lambiam09:47, 22 May 2023 (UTC)[reply]
Spreading sulfur will make the soil more acidic, so dissolving out the KNO3 in water and using this as fertilizer would avoid acidification. Graeme Bartlett (talk) 09:57, 22 May 2023 (UTC)[reply]
As stated above, saltpetre can be extracted from the mixture using water and can then be used as fertiliser. The remaining mixture of carbon and sulphur is harder to separate. It can be done by extraction with a non-polar solvent (carbon disulphide is suggested, but wasn't known yet) or by melting sulphur at 115°C, then filtering. It may be tricky to do. Or you can simply burn the C-S mixture, creating SO2 and CO2. Blow the smoke through a mixture of water and limestone (calcium carbonate) and you get wet calcium sulphite, which gets further oxidised to calcium sulfate. On sulphur-poor soils, it may be useful as fertiliser, but it's more commonly used as building material: plaster of Paris. This process is related to flue-gas desulphurisation and was invented around 1850, but doesn't require a huge suspension of disbelieve to do before that time. Directly throwing the gunpowder on the fields may work as a fertiliser, but the sulphur may do more harm than good. PiusImpavidus (talk) 10:43, 22 May 2023 (UTC)[reply]
Further thanks. So, if the main problem of using raw gunpowder as fertilizer cum soil treatment (I imagine it would also have an effect on soil textures and aeration) is acidification, might it be practical (and within the scope of late 17th-century know-how) to mix in a cheaply available alkaline material, such as crushed limestone? My fictional protagonists are not desperate to use the surplus tons of gunpowder at all costs; they just want to 'de-militarize' it cheaply – if they can't find an easy useful application, they might just dump it in the Baltic. (Yes, that might have deleterious ramifications, but they wouldn't know that. {The poster formerly known as 87.81.230.195} 90.199.210.77 (talk) 12:33, 22 May 2023 (UTC)[reply]
Once the potassium nitrate has been removed as already suggested, the remaining sulfur/charcoal mixture (when dry) would be a perfectly good dusting powder to use as a fungicide or pesticide, in particular for grapes. I assume that any self-respecting small European country would have a thriving wine industry.... Mike Turnbull (talk) 13:15, 22 May 2023 (UTC)[reply]
Which is used as a fertilizer! Thanks Lambiam, and the other responders. I'll have my 17th-century Baltics mix the surplus gunpowder with crushed limestone and sprinkle it on some fields. Close enough for fan-fiction. {The poster formerly known as 87.81.230.195} 90.199.210.77 (talk) 14:26, 23 May 2023 (UTC)[reply]
In situations where there was once a desk microphone (parliaments for example), it seems usual nowadays to have two, each with its own gooseneck, an inch or two apart. Our articles don't seem to mention the fact, let alone give a reason. Doug butler (talk) 05:51, 22 May 2023 (UTC)[reply]
Uses of dual microphones could be explained better in the article about Microphone practice. PA (Public Address) system engineers can use dual microphones in several ways:
The two microphone signals can be distributed to different listener groups such as local and international broadcasters, journalists, translators, recording equipment, etc. (saving on the simple expedient of using a signal splitter, see example) with assurance that each channel is unaffected by any filtering, switching, intrusion or censoring applied to the other channel.
For music performance where room acoustics are relevant, two near-co-sited microphones can serve in a stereo recording technique though this is not usually done for a parliament speaker.
Adding two microphone signals with equal gains but in antiphase results in cancellation of sounds (nulls) in some directions, see [2]. This can be useful both to reduce ambient noise and to allow higher voice amplification at public events before Audio feedback occurs. Philvoids (talk) 10:13, 22 May 2023 (UTC)[reply]
And if one fails, probably the other one will still function.
If there are two speakers (eg an interpreter or an interview situation), Each speaker can use a different microphone.
I'd assumed it was so they were free to move their head from side to side without the volume varying much. People who are not used to microphones are always fading in and out. NadVolum (talk) 12:19, 22 May 2023 (UTC)[reply]
NadVolum's suggestion is the most compelling so far. The antiphase trick works to reduce ambient noise pickup, though it relies on the performer being closer to one or the other; if midway it's the politician's voice that gets canceled, which can be a problem for the Hansard staff if for no-one else. I had several other thoughts, like deterring the speaker from "swallowing the mike" or even reducing the "spitting" on sibilants and "popping" on plosives, but the mikes are usually paired up too closely for that to be a factor. I peeked at a few microphone companies' websites, but they are strangely silent on the matter, though it must result in greater sales :) Doug butler (talk) 14:09, 22 May 2023 (UTC)[reply]
A young or very inexperienced speaker may find it stressful and unnatural to be instructed to "speak into" a single object microphone. With dual microphones one speaks more comfortably into open space between the microphones. Philvoids (talk) 13:17, 23 May 2023 (UTC)[reply]
I expect there are other ways, but one way is to put it on an audio CD, and then let iTunes rip it off (like it used to do whenever I played a CD on my computer!). Graeme Bartlett (talk) 10:50, 22 May 2023 (UTC)[reply]
On desktop (including laptop), you should be able to just drag the mp3 onto the Music app's icon in the dock, and it should start playing it and add it to your library. To get it onto your phone, you'd have to sync your phone with the desktop computer. -- Avocado (talk) 00:35, 24 May 2023 (UTC)[reply]
There's a bit more to it than that. I've extracted the US and UK relevant entries:
Fuel
RON
MON
AKI or (R+M)/2
"Regular Gasoline/Petroleum" in Australia, New Zealand, Canada and the United States
91-92
82-83
87
"Mid-Grade Gasoline" in the United States and Canada
94-95
84-85
89-90
"EuroSuper" or "EuroPremium" or "Regular unleaded" in Europe, "SP95" in France, "Super 95" in Belgium
95
85-86
90-91
"Premium" or "Super unleaded" gasoline in US and Canada (10% ethanol blend)
97
87-88
92-93
"Premium Gasoline" in the United States
96-98
86-88
91-93
"Shell V-Power 98", "Caltex Platinum 98 with Techron", "Esso Mobil Synergy 8000" and "SPC LEVO 98" in Singapore, "BP Ultimate 98/Mobil Synergy 8000" in New Zealand, "SP98" in France, "Super 98" in Belgium, Great Britain, Slovenia and Spain, “Ampol Amplify 98 Unleaded” in Australia
98
89-90
93-94
so there does seem to be a slight difference. Historically US made cars had larger, lower compression ratio engines than European (and Japanese) made engines. I don't know if this is still the case, but it might explain the differences. Martin of Sheffield (talk) 17:03, 22 May 2023 (UTC)[reply]
In Australia at least teh car manufacturers pointed out the the poor fuel quality historically made it far more difficult to reach emissions targets. Low octane low temperature fuel is cheaper than high octane fuels for high ambients. Greglocock (talk) 22:29, 22 May 2023 (UTC)[reply]
What has five leaves and looks like poison ivy?
I don't know how to find the question I asked earlier but I have more information.
Although it looks like poison ivy and sometimes there are three leaves, this plant has a leaf on the end and two pairs of leaves. The first pair, of course, looks like the pair of leaves in poison ivy.
Sorry, I don't carry anything I could use as a camera. But last week I was walking on a trail where this plant was very, very common, and I made a new discovery. It eventually becomes a full-grown tree, and there are many trees of this type on the trail, with the same leaf pattern--five leaves on each small branch.— Vchimpanzee • talk • contributions • 22:38, 22 May 2023 (UTC)[reply]
Just to note that poison ivy is absolutely a vine, especially as a mature plant. Like all vines, the young shoots may not be vine-like until they find a substrate to crawl up, but mature poison ivy can grow absolutely massive vines that are many years old. --Jayron3217:19, 23 May 2023 (UTC)[reply]
Found it. I decided to see what would happen if I did a Google search with the same question. This time a photo came up that looked like what I saw. Acer negundo. Wikipedia doesn't have a photo that would allow me to see the similarity, but there was one in the Google search results, and this site says "Box elder" beside the same photo.— Vchimpanzee • talk • contributions • 17:04, 23 May 2023 (UTC)[reply]
Ah, yes. Box elders are interesting in that, unlike most maple trees, they have a compound leaf, similar to many ash trees. I've never heard them called this, but the Wikipedia article notes "ash-leaved maple" as another name for box elders. The way to recognize a compound leaf, by the way, is that each leaflet is attached to a central rachis, which in the autumn will detach from the plant; this is not a proper branch of the tree, rather it's part of the leaf structure itself. While most notable on ash trees, you also find such compound leaves on other trees such as the box elder (you've already found) and mimosa trees, which are doubly compound leaves, and moringa, which are triply compound. --Jayron3217:37, 23 May 2023 (UTC)[reply]
""Ash-leaved maple" is the name generally used in the UK, where it is a fairly unusual specimen tree, sometimes found in parks and gardens. Maybe because the common ash is a well-known native here. It's not actually a true elder, although the leaves are similar. Alansplodge (talk) 17:10, 24 May 2023 (UTC)[reply]
Interestingly, the box elder's leaves more closely resemble the green ash (a common North American tree with a range overlapping the box elder) than they do the common ash, which is not well known on this side of the pond. Compare [4] and [5]. Regarding North American species which are unrelated to similarly named Eurasian species. It'sacommonproblem. --Jayron3218:26, 24 May 2023 (UTC)[reply]
Did the locomotive come with a full tender? Then the answer depends on the capacity of its fuel bunker – if it is snowed in, the snow can be used as a virtually unlimited water supply. The next unknown is how well the barrel is thermally isolated. The water has to be kept at about 100 °C while the outside temperature is about 0 °C. The heat loss has to be compensated by the heat of the burning coal. --Lambiam04:34, 23 May 2023 (UTC)[reply]
Sorry to disagree with Lambiam but it only has to be kept warm enough to stop the boiler freezing. 10°C ought to be enough for long term survival. However this is throughout the boiler, so at the firebox end it would need to be warmer. Once the fuel runs out then the boiler would need to be emptied via the blow-down valve to avoid damage, but then you have a "dead" locomotive needing a live one to pull it. Of course if you do drop some or all of the boiler water, then the running gear gets frozen solid, which it will do anyhow. See Snowdrift at Bleath Gill. Martin of Sheffield (talk) 08:07, 23 May 2023 (UTC)[reply]
We appear to have a different understanding of the concept of a locomotive (or actually its engine) being kept in steam. --Lambiam16:25, 23 May 2023 (UTC)[reply]
OK, fair point, I will admit I was thinking about simply ensuring the loco could be brought back to a working condition ASAP. If you want to ensure there is steam available, then next question will be at what pressure? Enough to move? Enough to work the brakes? Martin of Sheffield (talk) 21:31, 23 May 2023 (UTC)[reply]
Well, since you put it this way, "in steam" here means with enough steam to work the blower, mechanical stoker (any engine as big as the one I described would certainly have one), injector, brake pump, dynamo and train heat, but not necessarily enough to move. 73.162.86.152 (talk) 04:25, 24 May 2023 (UTC)[reply]
Depending on how much hope you have to get unstuck soon, you may want to keep some pressure in the boiler. If you can operate the blower, restart time can be cut from half a day to an hour or so, it may be nice to be able to run the steam heating of the carriages (I think that on Hercule Poirot's Orient Express the heating was shut off) and if you don't regularly operate the injector, the water in the hose connecting the tender to the locomotive may freeze, giving you a dead locomotive too. The water in the tender will freeze anyway, but this may take a few days. PiusImpavidus (talk) 09:24, 23 May 2023 (UTC)[reply]
No, I read the book fairly recently and there's nothing about the heating being off. Not in the movie either. You might be thinking of The Lady Vanishes, where all the characters move into an overcrowded hotel for one night for that reason. --142.112.220.184 (talk) 23:53, 23 May 2023 (UTC)[reply]
A different version maybe. I've seen two movie versions, one tv version and read the book a long time ago; I may be confusing some versions. PiusImpavidus (talk) 08:52, 24 May 2023 (UTC)[reply]
OK, I've done a back-of-the-envelope calculation. Assume the boiler+firebox is a cilinder, 10 m long, 2 m diameter, excluding the smokebox. That gives a surface area around 65 m2. With an insulation 15 cm think with thermal conductivity of 0.04 W/(m·K) and a temperature difference around 140 K, you loose about 2.5 kW of heat. Burning 1 kg of coal gives about 34 MJ of energy, a bit less if the coal is wet, and at least 5 MJ of that will leave the chimney as smoke, so let's say you get 25 MJ/kg burning coal. Conclusion: if you disable all steam-powered appliances and only have to counter heat loss through the walls of the boiler, you need less than kilogramme of coal per hour. With several tonnes of it in the tender, you can hold out for ages. I wouldn't be surprised if the insulation is actually thinner, given that this is such a minor heat loss. The limit will be your ability to prevent the water in your tender from freezing. Has the tender been equipped with tender water heating?
BTW, such big passenger locomotives were very rare in western Europe, where almost all steam locomotives were manually fired until the most demanding lines switched to electric traction in the interbellum. In eastern Europe, steam was used longer and in America, everything is bigger (as we say in Europe). PiusImpavidus (talk) 16:56, 24 May 2023 (UTC)[reply]
OK, so I guess we can safely call conductive losses negligible! However, shutting down all steam-powered appliances would not be an option in this scenario -- at the very least you need to run the mechanical stoker to keep the fire burning, and (at least occasionally) the injector to keep the boiler topped off, plus the blower to maintain a draft on the fire in the absence of exhaust steam from the cylinders! Plus, you would probably want to run the train heat so as not to make things miserable (or possibly outright deadly in the case of the Trans-Siberian) for the passengers, the dynamo (also for the sake of the passengers, as well as for safety at night and for any communications with the outside), the tender water heating to keep the water from freezing (and to melt the snow if that is to be used as a water supply) and the brake pump (which might be going at full blast if the train had been stopped by a passenger pulling the cord -- one possible scenario being that a passenger stopped the train because he/she had witnessed a murder aboard, and the train cannot be moved again because the killer had thrown some of the evidence outside so the murder has to be solved first). So, how much energy would it take to keep these things going? 73.162.86.152 (talk) 03:39, 25 May 2023 (UTC)[reply]
Garden plants' lifespan ?
We have had the same rhubarb, peonies and day lily plants growing in our garden for 30 years. They originated from cuttings taken from plants my mother had. How long can they live? 24.72.82.173 (talk) 15:44, 23 May 2023 (UTC)[reply]
Looks like pretty much forever. This says peonies can last 50 years, but that suggests that they can only be expected to die due to a new disease, or a bad frost or something. The common houseplant Epipremnum aureum is propagated throughout the world by cuttings, and was last observed by anyone to flower naturally was in 1964. Other clonally reproducing plants have been going since the end of the last ice age. Abductive (reasoning)15:43, 24 May 2023 (UTC)[reply]
Nested virtual reality in virtual reality
Virtual reality is when a VR player interacts with a virtual environment.
But what if the virtual environment itself contains VR players interacting with a nested virtual environment? Would the VR player then also be able to interact with the nested virtual environment? What about further levels of nesting, where a nested virtual environment in turn contains VR players interacting with another nested virtual environment that may itself contain another virtual environment nested inside, etc.? GeoffreyT2000 (talk) 16:25, 23 May 2023 (UTC)[reply]
If the simulation is sufficiently realistic, players should be able to play any number of games: operate a pinball machine, play Space Invaders in an amusement arcade, and play Half-Life: Alyx using a simulated VR headset. None of this is automatically the case; if the game developers have not catered for one of these potential possibilities, it will not be actually possible. This applies likewise for multiplayer games such as Population: One. It is theoretically possible, and I think practically feasible, to design a multiplayer VR game, say Droste, in which the players can start playing, among several games, a nested instance of Droste. --Lambiam16:45, 23 May 2023 (UTC)[reply]
There is a serious scientific hypothesis that our own apparent reality is actually a virtual reality existing in a simulation created, it is presumed, by some form of advanced beings. It is further conjectured that those advanced beings' 'reality' (including them) is itself a simulation created by some higher order of advanced entities. This "turtles all the way up" conjecture has no theoretical limits. Some people look for 'glitches in our matrix.' Good luck to them, I say. {The poster formerly known as 87.81.230.195} 90.199.210.77 (talk) 23:24, 23 May 2023 (UTC)[reply]
Could be done in robotic simulators like V-REP where you can have multiple robots running around and seeing each other and behaving accordingly. I don't suppose it would be easy to create a version of V-REP that runs inside V-REP, but in theory it could be done. https://www.coppeliarobotics.com/downloadsGreglocock (talk) 00:39, 24 May 2023 (UTC)[reply]
You'd need an extremely large force to hold it together. What do you imagine the inter-electron distance to be? Using the same distance as the inter-molecule distance of water, 0.31 nm,[6] the number of electrons in 1 cm3 of electron fluid equals the number of water molecules in 1 cm3 of water. A back-of-the-envelope calculation comes out at 33.5×1018 electrons, which will have a combined charge of 5.36 C. Imagining this as consisting of two parts, each with halve this charge, separated by a distance of 1 cm, the electrostatic force by which they repel each other will exceed 600 TN. So you cannot just put this in a viscometer; to determine its viscosity needs to be done theoretically. I am inclined to think that the electrons will pack in a regular lattice to minimize the potential energy; deforming it may then require a huge amount of energy. But I am not enough of a theoretical physicist to make a more definite assertion. --Lambiam13:12, 24 May 2023 (UTC)[reply]
Is it as simple as the force of the E field multiplied by the distance of the accelerator multiplied by how many times the particle has gone through the accelerator?
That would be true for a cyclotron, though there you would usually just use the maximum possible radius to get the final energy of the particles. I you are talking about a synchrotron (like the LHC) it's more complicated as you can't use static electric fields but need some kind of resonator (e.g. a microwave cavity) in which an standing electromagnetic wave is induced. The energy gain per lap then depends on when in the phase of the em wave your particle arrives at the resonator. A little counter-intuitively you don't want your particle to get there when the E-field is strongest as that will mean losing most of you particles (then ones that are not perfectly in phase). Additionally, the field won't be static for the time it takes the particle to cross the gap and it likely also not be homogenous at the edges.140.181.85.173 (talk) 11:33, 24 May 2023 (UTC)[reply]
Do you know if it's assumed that the E field is able to impart the same force at relativistic speeds as non relativistic?
I know we don't know exactly what an E field is, but we know they change at c so might they not be able to impart all of their force to a relativistic particle? Byron Forbes (talk) 23:47, 24 May 2023 (UTC)[reply]
Pest detection
In a large food warehouse, or in a big city, are microphones and cameras used to detect rodents? What about microphones to detect termites or other insects? If cameras and microphones aren't being used, are there any startup companies or academic work being done on it? Rich (talk) 20:13, 24 May 2023 (UTC)[reply]
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