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March 1

Force of arrows in wars

In past people used to use arrows during battles. The Hollywood movies show that they fire arrow in the sky at 45 degree angle and when it reaches enemy soldiers far away the arrows pierce their amours and kill them.

Normally if we throw something when anything is near then the force will be very high but more distance means the speed decreases and it will not have much damage. shooting arrow to someone standing right in front of me can hurt him severely but those who are afar away how will they get hurt. Arrows are also not heavy like spears. 2409:40E1:1075:838A:F867:C146:EE95:3B4A (talk) 06:48, 1 March 2025 (UTC)

Don't believe what you see in Hollywood movies, or any other movies. An arrow is designed to travel a significant distance and still inflict damage. See arrow. Shantavira|^{feed me} 09:20, 1 March 2025 (UTC)

The arrow article doesn't seem to address anything about effect at distance. Without giving even a hint of credence to anything from movies, Archery#Physics has an interesting note regarding the higher velocity of an arrow vs a spear. That could offset an effect of reduced weight for a fixed distance, or allow at least some damage at a greater distance. Any projectile has an effective range. "Far away" is not a well-defined term. Someone skilled in using a bow and arrow as a weapon would know its range against specific types of targets. DMacks (talk) 10:53, 1 March 2025 (UTC)

There has been much scholarly research into the use and effects of medieval archery; see English longbow#Use and performance and associated links for details. The main sources for researchers are a large haul of well preserved 16th-century longbows recovered from the Mary Rose and Toxophilus, a contemporary treatise on military archery by Roger Ascham. Alansplodge (talk) 11:38, 1 March 2025 (UTC)

From a filmmaking perspective, artistry is more important than historical fact. Stanleykswong (talk) 18:29, 6 March 2025 (UTC)

An arrow can travel way much faster than a thrown object. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:58, 1 March 2025 (UTC)

When an arrow is fired at a 45-degree angle, it converts kinetic energy into potential energy as it ascends, slowing down while gaining height. On the descent, potential energy is converted back into kinetic energy, increasing speed as height decreases. Some energy is also lost to air resistance. --136.56.165.118 (talk) 00:24, 2 March 2025 (UTC)

Note that (ignoring air resistance) the total energy (sum of kinetic and potential energy) remains constant throughout the arrow's flight, demonstrating the principle of conservation of energy. 136.56.165.118 (talk) 00:32, 2 March 2025 (UTC)

Also worth noting is that under ideal conditions (the arrow projected from a fixed-velocity at a level target and air resistance is negligible) a 45-degree angle maximizes the product of the projectile's vertical and horizontal velocity components, resulting in the greatest range. 136.56.165.118 (talk) 02:32, 2 March 2025 (UTC)

You are right, arrows fired at a 45 degree angle have the longest range. Technically, a medieval arrow could have a range of 300m or more if fired at a 45 degree angle.  But war is not about how far your arrow can shoot. Your arrows must be fast and accurate enough to penetrate enemy armor. Stanleykswong (talk) 18:46, 6 March 2025 (UTC)

In ancient wars, archers usually fired arrows directly at enemies about 50 meters away. If the distance exceeds this distance, there will not be enough kinetic energy to penetrate the enemy's armor. Stanleykswong (talk) 18:27, 6 March 2025 (UTC)

At battles like Agincourt and Crécy, English longbowmen used massed volleys to devastating effect, a precursor to "fire for effect" (FFE).^[1] Thanks to conservation of energy: what goes up, must come down -- with the same energy as when fired, minus only that from air resistance. 136.56.165.118 (talk) 20:28, 6 March 2025 (UTC)

To summarise others' responses — (1) Assuming no strong winds and no obstructions requiring specific angles, a 45-degree angle generally produces the maximum range. (2) The farther an arrow goes, the more energy it loses to air resistance, so it can do less and less damage to its target. (3) Not specified by others, but the specific point at which a target is hit can vary the effects significantly — a slow arrow at an unprotected point can do more damage than a fast arrow at a strong point. Consider a passage near the end of the biblical book of I Kings: But a man drew his bow without taking special aim and struck the king of Israel through the joints of his armor. So he said to his charioteer, "Turn around and take me out of the battle, for I am badly wounded!" In this setting, the archer was shooting at a group of enemy soldiers (probably at a long distance, since at a short distance he'd have a better effect if he aimed at a specific soldier), and the king was badly wounded because the arrow happened to hit him at a weak point. Nyttend (talk) 20:35, 6 March 2025 (UTC)

A safe assumption to make: fictional movies, are not documentary depictions of pre-modern combat and how it "really worked". Historian Bret Devereaux on armor and ranged combat: [2] [3] From the latter, initial emphasis mine:

Mike Loades (cited above) claims that there are no scenes of bowmen firing high arcs outside of siege contexts in the whole of medieval art. I certainly have not seen one. Of course, bowmen fire arrows upwards in siege contexts, but the 45-degree maximum-range arc doesn’t appear in artwork featuring battlefield conditions. Now, at Agincourt (1415), the initial English volleys do seem to have been at very long range, but (following Keegan, The Face of Battle (1976), inter alia) these volleys weren’t intended so much to cause damage as to goad the French into a foolish attack (a psychological impact!). The actual killing the longbows did happened once the French began advancing.

In fictional depictions, armor tends to veer towards the completely useless, enough that TVTropes has a page called Armor Is Useless. Well-armored combatants having attacks just glance off their armor doesn't make for very compelling viewing. And, our plucky heroes being slaughtered because they lack the resources to get their hands on effective armor or weapons capable of landing blows against armored foes, is challenging to craft narratives around.

But in reality, armor was incredibly useful, and you wanted to have as much of it as you could manage to get, and people in fact generally did just that. Ranged fire at extended range had little effect aside from psychological—and fire with that in mind was employed sparingly, as ammunition and muscle power to propel the projectiles were things both in limited supply. No belt-fed crew-serviced automatic weapons powered by chemical explosives here I'm afraid. --Slowking Man (talk) 05:35, 8 March 2025 (UTC)

Making movies is to present a good story.  Audiences love tragedy and comedy.  It is difficult to make a war scene into a comedy, but it is relatively easy to make it into a tragedy.  A group of brave soldiers, wearing useless armor and carrying crudely designed bows and arrows, fight against the invaders with powerful weapons. From a storytelling perspective, it's a great scene. Stanleykswong (talk) 08:55, 8 March 2025 (UTC)

March 4

Is this tool use in the goffin?

What do you think of this video that I saw on Reddit? It appears to show a goffin using a walnut shell as a cup to drink water. Does this count as tool use? 146.90.140.99 (talk) 22:44, 4 March 2025 (UTC)

Opinion would likely differ depending on one's definition of 'tool' – if he modifies the shell at all, I would definitely say yes, if not, some might say no. Overall, it seems consistent with the species' behavioral intelligence, which definitely includes tool invention, modification and use. {The poster formerly known as 87.81.230.195} 94.2.64.108 (talk) 00:09, 5 March 2025 (UTC)

Most people who use, say, a screwdriver, use it "as is", bought in a store or found in a tool shed, without making any modifications to it. Still, I think almost everyone will agree this is evidence of tool use by Homo sapiens. We have an article on Tool use by non-humans, which documents this and other differences in how scientists define the notion.  ​‑‑Lambiam 11:28, 5 March 2025 (UTC)

Lady Chatterly in her car was driven home by her chauffeur Mellors when the engine made a strained noise and stopped. "Beg pardon ma'am" said Mellors, "but something's amiss with the motor. I'll get out and try to fix it". "What a gallant fellow you are, Mellors" said Her Ladyship and reached for the toolbox, intending to help in any way she could. "Mellors, would you like a screwdriver?". "That's awfully decent of you ma'am but I should fix this engine first". Philvoids (talk) 13:04, 6 March 2025 (UTC)

Tools are modified. A screwdriver is a modified item. You can't go out and pick a screwdriver from the screwdriver tree. Walnut shells are not modified. You can easily find a lot of walnut shells in nature. It isn't a matter of who modified it. You can't claim that Bob didn't modify his screwdriver, so it isn't a tool. It is simply a matter of separating things into stuff found in nature and stuff created by some form of intelligence to perform some task. 12.116.29.106 (talk) 13:08, 6 March 2025 (UTC)

See also, Cow tools. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:57, 6 March 2025 (UTC)

You can also think about it from another perspective: most people just go to the hardware store to pick out a suitable screwdriver, which is no different from a bird picking out a suitable walnut shell to drink water.

You might say someone designs and manufactures screwdrivers in a factory so people can go to the hardware store and choose the one that best suits your application.  However, by the same logic, you might also think that nature "designed" and "made" a series of walnut shells, and that the bird simply went out and selected the right walnut shell to drink water. Stanleykswong (talk) 14:51, 8 March 2025 (UTC)

Correct. By altering the definition of "tool" you can make any point you want. If we think about it from another perspective, someone might think about doing some work and then think about something that would help. The idea is good. So, the idea is a tool. That means that all thoughts are potentially tools. So, anything that can think can be a tool. If walnuts are tools, that must mean that trees think and likely dream about squirrels through the winter. 12.116.29.106 (talk) 12:59, 11 March 2025 (UTC)

courtesy link: Tanimbar corella, aka Goffin's cockatoo. (Until now the only goffin I knew of was Carole King's past partner.) —Tamfang (talk) 22:55, 7 March 2025 (UTC)

March 6

Draining swamps

I attempted to search for the answer, but any relevant information was undiscoverable amongst political slogans.

On a very basic level, how can a low-lying swamp be drained? Some swamps can be drained by creating a steep-slope artificial river, e.g. the Old Bedford River, but that wouldn't work in a consistently low-lying environment. I grew up on the edge of the former Great Black Swamp, which was converted into productive farmland, but it's extremely low-lying — local rivers flow toward Lake Erie, but in 120km they fall just 100m — so this wouldn't have worked well. As well, drainage was accomplished in the 19th century by local residents, so internal-combustion-powered machinery and huge steam-powered machinery seemingly would have been out of the question. Nyttend (talk) 20:46, 6 March 2025 (UTC)

The Dutch use windmills. Abductive (reasoning) 21:05, 6 March 2025 (UTC)

They build a dike around the area and dig a canal (Dutch: ringvaart) surrounding the dike. The canal functions as a reservoir, higher than the drained area, into which water is pumped.  ​‑‑Lambiam 21:22, 6 March 2025 (UTC)

Our article mentions the (steam-powered) Buckeye Traction Ditcher as expediting the draining of swampy areas.  ​‑‑Lambiam 21:13, 6 March 2025 (UTC)

Really, this can be done very low tech. You can use tile drainage, or just run known irrigation methods backwards, such as a Screw of Archimedes or other pump, human or donkey-powered. Abductive (reasoning) 21:31, 6 March 2025 (UTC)

Ah, I misunderstood what this machine was; I overlooked the record-pace tile laying and figured it was just something to dig ditches, and envisioned them as being only an ancillary aspect of the process. Nyttend (talk) 02:37, 7 March 2025 (UTC)

The Brits drained The Fens centuries ago, likewise using windmills. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:48, 6 March 2025 (UTC)

To this Dutchman 100 metres in 120 kilometres doesn't sound like extremely flat. We have a drop of about 8 metres in 120 kilometres, but it's only in the lower part of the country that pumps are required. They used to be wind powered (starting around 1500), but apart from some small wind pumps for local use, those are now mostly seen as industrial heritage or tourist magnets. There was a switch to steam in the late 19th century (one still in use, some others preserved as industrial heritage), then to a mix of diesel (a few pre-1930 diesels are still operational, but most are from the 60s and 70s) and electric pumps. The power for the electric pumps comes partially from wind turbines, so we're back at wind power.

But you can even drain a swamp without any pumps, making use of the tides. Build some drainage cuts and a dike with a check valve and you can lower ground water level from close to high tide to close to low tide, easily a 2 metre drop. It was already common in the 13th century. PiusImpavidus (talk) 10:26, 7 March 2025 (UTC)

TBF, the swamp under discussion is near Lake Erie (whose tides are negligible), not any ocean shore. The fact about the tides is pretty cool regardless, though. -- Avocado (talk) Avocado (talk) 13:11, 7 March 2025 (UTC)

March 7

Milk in soda cans with nitrogen?

Being someone who dislikes plastic bottles I've been trying other figure out how to get products into soda cans (plastic lined I know I know) and recently looked into canning milk. After learning that the primary form of strength in soda cans comes from pressurizing the contents, I found that you can't carbonate milk because CO2 will accelerate its decline but it seems like nitrogen should be a usable gas? ^Thanks,L3X1 ◊distænt write◊ 03:14, 7 March 2025 (UTC)

Soda cans in use today are extremely thin and it wouldn't surprise me if the internal pressure supplies the bulk of the rigidity, but a) who says the container must be rigid or strong and b) soda cans used to be a great deal stronger. Indeed, milk cans seem plenty sturdy. Matt Deres (talk) 03:20, 7 March 2025 (UTC)

Evaporated milk is routinely sold in cans. That article says "Evaporated milk generally contains disodium phosphate (to prevent coagulation) and carrageenan (to prevent solids from settling), as well as added vitamins C and D." HiLo48 (talk) 03:34, 7 March 2025 (UTC)

See the various containers produced by Tetra Pak, commonly used in Europe. I regularly buy both orange juice and UHT milk in 1-litre tetra-pak type rectangular containers, and currently have one of custard also: I believe similar containers are used in the USA – see Milk carton. I suspect this is a superior solution to cans, which would otherwise already be in use. {The poster formerly known as 87.81.230.195} 94.2.64.108 (talk) 06:05, 7 March 2025 (UTC)

An aluminium sheet does not readily stretch, which means that the application of moderate forces can bend and fold it (including crumpling), but not much else. For a cylindrical aluminium can this means that its volume decreases when it is deformed. Like any liquid, milk is virtually incompressible, which means that a full and well-closed can should be rather rigid. (I have no full cans of any liquid at hand to test whether practice agrees with theory.) A can that is not full is less rigid, because the gas inside is easily compressed.

An advantage of packaging in a nitrogen atmosphere is that it keeps the lipids in the milk from oxidizing.  ​‑‑Lambiam 19:06, 7 March 2025 (UTC)

I don't see any downside to using nitrogen in milk packaging. After all, 80% of the air is nitrogen, so we only need to remove the oxygen in the air. The removed oxygen can also be sold separately to subsidize the packaging cost. Stanleykswong (talk) 09:14, 8 March 2025 (UTC)

March 8

Weigh a bed using 4 bathroom scales

The actual purpose is to weigh a human who has trouble standing on a scale. Idea is put one scale under each bed leg and add up the 4 readings to get the weight of the bed. Then do the same when the human lays down on the bed, and subtract. this work? Thanks. 2601:644:8581:75B0:0:0:0:55E8 (talk) 08:54, 8 March 2025 (UTC)

Why not reset the scale to zero after placing it under the bed legs? By doing this, you simply add the four readings together. Stanleykswong (talk) 09:01, 8 March 2025 (UTC)

A bed would be too heavy even for four normal bathroom scales. Better to use a plank of wood and two scales. Shantavira|^{feed me} 09:11, 8 March 2025 (UTC)

The weight of the IKEA NEIDEN bed frame is 14.89 kg and the weight of the LUROY slatted bed frame is 8.51 kg.  The bed itself doesn't add much weight compared to the 600-pound weight limit. Stanleykswong (talk) 09:26, 8 March 2025 (UTC)

Yes, that works. Just make sure the centre of mass doesn't move between the four readings, or the weight may be redistributed over the scales. PiusImpavidus (talk) 10:02, 8 March 2025 (UTC)

The redistribution shouldn't affect either total, though, should it? -- Avocado (talk) 13:30, 8 March 2025 (UTC)

Agreed, the weight distribution between the bed legs should not affect the total weight. Stanleykswong (talk) 13:38, 8 March 2025 (UTC)

Four is a bad number to use. The problem is if they're all load bearing it might not be stable; weight might shift between corners due to the slightest of shifts, or even due to the scales opposing each other. If you can find a way to use three it should be much more stable. You could place two at corners but a third in the middle of the opposite edge.

This also helps with another problem that bathroom scales are often only approximate. Taking readings off three or four will multiply this error by three or four. No easy fix for this except take readings more than once. Perhaps weigh the bed before and after your human is on it, and if the discrepancy is large also re-weigh your human and average the results. --2A04:4A43:909F:FB44:28A1:3B73:AC99:CE94 (talk) 13:46, 8 March 2025 (UTC)

I believe your car is likely on four wheels as well, does it have the stability issues you describe?  All four wheels are load-bearing and I believe it is very stable.

I agree with you that most bathroom scales are inaccurate, especially when you compare it to the scales used in hospitals or clinics.   But the typical deviation is only 0.05 to 0.15 kg. Stanleykswong (talk) 14:26, 8 March 2025 (UTC)

A car doesn't have the problem I describe but a car is a highly engineered device with particular attention paid to balancing load between wheels, keeping all four wheels on the ground as much as is possible, using its suspension.

Many of us have had to deal with a piece of furniture with four legs that doesn't sit stably on all four. Maybe the floor surface is uneven, or its legs. A wooden chair/table on a rustic tiled floor e.g. Typically two opposite legs are always in contact but only one of the other two is at a time, as it wobbles between them. Put springs under both of them and it might oscillate, and that's effectively what you are doing with scales. A three legged item doesn't have this problem, can be stably placed on even a very uneven surface. --2A04:4A43:909F:FB44:24EA:EF2B:7143:1443 (talk) 15:49, 8 March 2025 (UTC)

If the four scales are identical and the bed is not already wobbly on a flat floor, I don't expect this to be a problem. The relation between the downward force and the vertical displacement of the surfaces of the scales supporting the weight is not linear. If the centre of mass of bed + patient is over the centre of the rectangle formed by the scales, the potential energy is minimized when the springs of all four scales are compressed equally. Even if the bed is wobbly, just use one or two shims under the shorter legs.  ​‑‑Lambiam 19:07, 8 March 2025 (UTC)

Having the weight on 4 scales instead of 3 leaves one degree of freedom: how much of the weight is on the legs of one diagonal combined and how much is on the legs of the other diagonal combined. It shouldn't change too much under shifts in the centre of mass, but this could be a problem for beds with inconvenient elastic properties. For example, if it's bistable under torsion deformations. Allowing for some elastic deformation of the bed, the distribution gets more equal. If the bed wobbles, the legs in intermittent contact with the ground never carry more than a tiny fraction of the weight.

What could be a serious problem with more than 3 scales is elastic deformation of the floor. When the person taking a reading walks to one of the scales, the floor locally bends down, redistributing the weight away from that scale, leading to a measurement that's too low. This could be an issue if the elastic deformation of the floor is significant compared to that of the scales and the bed. That is, on a wooden floor.

The deviation of the scales would most likely be a systematic error, so taking the same measurement twice won't help. Worse, if all scales are from the same batch, you can expect them to have the same error, so that really adds up. On the other hand, the weight of a person fluctuates over the course of a day by several hectogrammes, so outside special contexts where such factors affecting weight are properly taken into account, measuring a person's weight to an accuracy better than 5 hg is rarely useful.

Alternatively, you could build scales large enough for the entire bed. Something like Sir Bedevere's largest scales will do. Or a weighbridge. My municipal waste dump has one; they weigh your car before and after dumping and charge for the difference.

PiusImpavidus (talk) 19:33, 8 March 2025 (UTC)

"Worse, if all scales are from the same batch, you can expect them to have the same error, so that really adds up." True, thus I would simply weigh myself on a known accurate scale, before plopping on an unknown one. It works every time. :-) Modocc (talk) 19:49, 8 March 2025 (UTC)

"What could be a serious problem with more than 3 scales is elastic deformation of the floor.". There could be a number of triggers, for them to find a new stable state. The person on the bed could move, or even depending how sensitive things are just breathe. And unless you have some way of reading them all at once such a shift could completely ruin the readings. Don't forget the ones that might change together are on opposite corners. If you take readings of them in order there could be several seconds during which a shift happens undetected while you are looking at one of the ones that does not change. --2A04:4A43:909F:FB44:683A:7FEE:BE65:E75 (talk) 20:11, 8 March 2025 (UTC)

Good point. Yes, if you want a person's accurate weight, you have to take readings from different scales at the same time. This can be done by using scales with USB, RS485 or wireless connection and connecting them to the same mobile app or computer program. I don't know if there are any home scales with this kind of connectivity. If not, then you may need to use industrial scales. In this case, rather than purchasing three or four industrial scales, it may be cheaper and easier to simply use a large bed scale, such as Marsden M-955. They're actually a bed with a weight sensor on each of its four legs. Stanleykswong (talk) 20:53, 8 March 2025 (UTC)

There’s no doubt that a three-legged bed won’t wobble. This can and often is done with beds with four legs, as it is impossible to keep all four legs even. However, this can happen regardless of whether there are scales underneath it.  So, technically, if the bed doesn't wobble without scales underneath it, it won't wobble if the four scales are identical or nearly identical. Stanleykswong (talk) 19:52, 8 March 2025 (UTC)

Which is what I wrote. However, if the floor itself is not flat or unstable, for example if there is an earthquake while the measurements are done, or the floor consists of spring mattresses, all bets are off.  ​‑‑Lambiam 10:00, 9 March 2025 (UTC)

References

Truck in Alice to Nowhere

Much of the action in this 1986 Australian film involves a truck with a very "army surplus" appearance, that I, a non-enthusiast, have been unable to identify. My copy of the film is of poor quality, possibly ex-VCR, but the vehicle has several distinguishing features: it has one rear axle, so is probably 4x4. The engine hood is shaped from flat surfaces, reminiscent of some GM WWII trucks, and the logo above the radiator appears to be three letters of similar size: most likely ATO or ATC, but the "T" might be a "Y". Notably, it is a cab over design; the driver's door is directly over the front wheel and part of the engine cowling is forward of the front wheels. In the YouTube copy it is first seen at 43:33 and intermittently thereafter.

As the film appears to be based on the documentary The Back of Beyond, it is surprising that the producers did not use an AEC Badger as driven by Tom Kruse, unless these "army surplus" vehicles were more readily available.

IMDb says "The truck seen was actually a 1965 Army Truck. Three trucks were utilized for the production. One of the trucks took six weeks to build due to the number of modifications. One of the trucks had to be converted to diesel so it could drive through water for the river crossing sequences." Doug butler (talk) 12:46, 8 March 2025 (UTC)

A Truck, Cargo, 2.5 ton GS International No.I Mk III perhaps?

Film makers before the 1990s, esecially if on a low budget, were not very fussy about vehicle accuracy and tended to use what was available as long as it looked about right. A notable example is the use of undisguised US-built postwar tanks standing in for German panzers in Patton (1970). [4] Alansplodge (talk) 13:11, 8 March 2025 (UTC)

I don't think there can be any doubt. The underlying similarities are overwhelming, and the descriptions tally well with the IMDb entry. Thanks Alan. Doug butler (talk) 19:58, 8 March 2025 (UTC)

I assume this is a side view of one of the trucks, modified for the film shoot. The protruding bonnet may have been one of the modifications.  ​‑‑Lambiam 18:49, 8 March 2025 (UTC)

That poster is a great find. I don't know how you do it. Thanks Lambiam. Doug butler (talk) 20:05, 8 March 2025 (UTC)

Resolved

Asymptomatic reverse-zoonotic diseases

Our article on Orthohantavirus notes that most species cause chronic, asymptomatic infections in their rodent hosts, and they only produce symptoms upon transmission to humans. Are there any reverse-zoonotic pathogens of any sort that do this, i.e. their natural reservoir is humans, and they don't cause any illness in us, but they can spread to some other species and cause an illness? Reverse zoonosis only covers human illnesses. Nyttend (talk) 20:53, 8 March 2025 (UTC)

My first thought is yes, probably, but how would we know? And if we did know, how would we know we hadn't caught it from animals in the first place? Shantavira|^{feed me} 09:56, 9 March 2025 (UTC)

There's an asymmetry here, which is the "animals not having any symptoms" premise cannot possibly be true, especially given the definition of symptom. Symptoms in humans, by contrast, are over-reported. Another issue is, how would you even know if a population of wild squirrels is experiencing a 1% increase in their mortality rate? But an unexplained 1% increase in the human mortality rate would be a catastrophic emergency. Abductive (reasoning) 12:02, 9 March 2025 (UTC)

Nyttend is doubtless using the looser colloquial meaning of 'symptoms' (experienced by the sufferer), which includes what are more correctly distinguished as signs (visible to an observer), per the linked article.

Who originally gave what to whom is not really an issue if an infection has been ping-ponging between host species for perhaps millennia. There remains the original proposition, that some infections might be sign-and-symptomless in humans but cause illness in an animal species.

Presumably one might be identified by observing some sickness in an animal species, establishing its cause as a particular pathogen, and then discovering that humans harbour and transmit that pathogen without suffering any ill effects. Anthropocentrism seems to have led to little research or publication about such pathogens, but it seems very unlikely that none exist. {The poster formerly known as 87.81.230.195} 94.2.64.108 (talk) 13:53, 9 March 2025 (UTC)

I'm just relying on what the Orthohantavirus article says: Hantaviruses in their natural reservoirs usually cause an asymptomatic, persistent infection. If you disagree, Talk:Orthohantavirus is the place to discuss it. IP, you're thinking along the same lines as I was. As far as anthropocentrism, I suppose such a disease would be more easily found in species significant to humans, e.g. livestock. Nyttend (talk) 22:10, 9 March 2025 (UTC)

We have an article at asymptomatic that includes a list (some of which are dubiously asymptomatic to my untrained eye, but it is what it is). You could click through and see if any of them cause illness in animals. I didn't immediately see any obvious candidates, but it's a long-ish list. Matt Deres (talk) 00:08, 10 March 2025 (UTC)

March 10

Fugitive reagent

Thirty years ago or so I was using caustic soda in the well-known hobbyist-level circuit board printing process, and kept the granules in a ground-glass stoppered jar, kept in a steel locker in my home workshop and after the job forgot about it. Twenty years later I found the key and was surprised to find half the material apparently evaporated past the stopper and the painted surface inside the locker a rusty mess.

Attempts to remove the stopper by chilling the jar and heating its neck failed and ended when I smashed the jar and safely disposed of its contents. Our article has a possible explanation for the the glass binding.

But how did the stuff escape? Doug butler (talk) 02:24, 10 March 2025 (UTC)

In contact with air, caustic soda reacts with carbon dioxide, an acidic oxide, to produce sodium carbonate and water, in this reaction:

2 NaOH + CO₂ → Na₂CO₃ + H₂O.

Of course, the sodium carbonate is to some extent water-soluble (washing soda). Given enough time, all of the caustic soda may have been converted. Sodium carbonate may decompose into sodium oxide and carbon dioxide:

Na₂CO₃ → Na₂O + CO₂.

I am not sure at which temperature this happens. The infobox at Sodium carbonate states: "decomposes (monohydrate) 33.5 °C (92.3 °F; 306.6 K)" but does not state the reaction explicitly.

If these reactions were involved, the question remains how the sodium oxide escaped. It cannot have been by sublimation, as this occurs only at 1275 °C.  ​‑‑Lambiam 08:19, 10 March 2025 (UTC)

Using the data from our articles on these substances and H₂O, I calculate that NaOH·H₂O has a specific volume of 31.7 cm³/mol, while NaO has 24.9 cm³/mol, which explains some of the reduction in size of the substance in the jar. Additionally, much of the original volume may have been air between the grains of soda crystal, while the oxide may have been more of a compact powder.  ​‑‑Lambiam 08:40, 10 March 2025 (UTC)

Lambiam I am reasonably certain the decomposition reaction for the monohydrate would just be the reverse of the first reaction you gave, Na₂CO₃·H₂O → 2NaOH + CO₂. Note that anhydrous sodium carbonate has a melting point in the same infobox, much hotter than the decomposition point for the monohydrate. It doesn't really make sense that the monohydrate would give up carbon dioxide and water but the anhydrous compound would not give up carbon dioxide at the same temperature. --Trovatore (talk) 20:45, 13 March 2025 (UTC)

Unresolved

There is no doubt that air was able to enter the jar, and the caustic soda absorbed enough water vapor to clump the powder, but not enough to make a liquid solution. CO₂ in the air became carbonate or bicarbonate, some of which is most likely the powder deposit below. Nothing remarkable there. But wherever the clump is exposed to the air it has been abraded and, witness the peeled paint and rusted metal, escaped past the ground-glass "seal". Other lockers containing obsolete junk valuable spares were not so affected.

Can an ionic solid, at molecular level, "hitch a ride" with water vapor? I know from experience, that precautions must be taken when adding even small quantities of caustic soda to water, otherwise your nasal membranes suffer. Can it be related to the well-known susceptibility of seaside roofs and motorcars to rust out prematurely? Doug butler (talk) 20:12, 11 March 2025 (UTC)

Any molecules getting loose by spontaneous sublimation could, and eventually would, escape equally spontaneously; assistance by water vapor would not promote this. But are you sure the remaining substance was not simply compact sodium oxide? If the volume of the original caustic soda was one third air, the volume of the remaining substance, after all the water escaped resulting from the net reaction 2NaOH·H₂O → Na₂O + 3H₂O, would be reduced by 48%.  ​‑‑Lambiam 22:57, 11 March 2025 (UTC)

I know nothing of Na₂O, but am well acquainted with caustic soda clumping if the container is left unsealed, and presumed it to be something similar. Doug butler (talk) 13:02, 12 March 2025 (UTC)

It seems unlikely. As Graeme notes below, even sodium hydroxide is deliquescent — it will suck water out of the air under ordinary conditions. I don't have specific data but I'd bet heavily that sodium oxide is even thirstier. The reaction proposed by Lambiam might go forward at a high temperature, with some sort of one-way valve that would allow water vapor out but not in. --Trovatore (talk) 19:26, 13 March 2025 (UTC)

Also sodium hydroxide will absorb water from the air until it dissolves in water. I suspect that it dissolved and diffused through condensed water to get through the crack. You probably could have soaked the jammed jar in water to get it open. Too late now! Graeme Bartlett (talk) 10:10, 10 March 2025 (UTC)

Yes, a pity. It was a very cute jar: barely visible in the photo, but it had an etched label appropriate to its contents. Doug butler (talk) 11:34, 10 March 2025 (UTC)

March 12

Turning a train around quietly

Which arrangement produces less noise, a reversing wye or a balloon loop? Because with a wye, there can be a tremendous clattering as the slack runs in and back out, plus hissing and squealing from the brakes (the latter also varying annoyingly in pitch, because the braking is at very low rotational speeds and any irregularities in the wheels and/or brake shoes will change the pitch of the noise), and with steam or (especially) diesel traction also loud puffing or roaring noise from the engine as the trains restart from a dead stop -- whereas with a balloon loop, these sources of noise are absent, but there can be an ear-splitting screech from the wheels skidding on the rails, and sometimes also loud pops as the wheels break or regain adhesion. So, out of these two methods for turning a train around, which one is less bad in terms of noise pollution (not only the amount of noise in absolute terms, but also perception thereof)? 2601:646:8082:BA0:24C8:7879:FEC5:96E (talk) 03:18, 12 March 2025 (UTC)

I doubt if there's much to choose between the noise levels, but I'd guess that the duration will be shorter on the loop, since the train just goes continuously round it once, whereas with the Wye (rail) the train has to run out its length on the first 'leg', stop, reverse a long way along the second leg, stop, then proceed back along the third leg, which would surely take more than three times as long as the loop. {The poster formerly known as 87.81.230.195} 94.2.64.108 (talk) 05:36, 12 March 2025 (UTC)

If it's only about changing direction of travel rather than turning the entire train around, then a passing loop would be a quieter option because you only have to move the locomotive to the other side. --Wrongfilter (talk) 06:17, 12 March 2025 (UTC)

Why not simply use a turntable, it's space-saving, fast and quiet. Stanleykswong (talk) 19:14, 12 March 2025 (UTC)

Hm. American freight trains can be more than 2 km long. Try finding a turntable for that. --Wrongfilter (talk) 19:42, 12 March 2025 (UTC)

American freight trains may be over 2 kilometers long, but I'm sure the locomotives are not.  All you need is a turntable for the locomotive. Stanleykswong (talk) 21:12, 12 March 2025 (UTC)

Only if it's not bidirectional. Commonly they are, or are grouped so the whole group can go either way. --142.112.222.162 (talk) 21:58, 12 March 2025 (UTC)

Yes, you're right.  Turntable only works for bidirectional carriages and freight cars. It is not suitable for unidirectional carriages because they only have doors on one side. Stanleykswong (talk) 07:25, 13 March 2025 (UTC)

I don't know what is meant by 'unidirectional carriages' but if it is locomotives that have a preferred operating direction, or something like a passenger observation car (coach, wagon) with a particular end that should be at the end of the train, turntables are very suitable. Modern 'hood' units can in fact be operated in either direction, but the low or short hood end forward is preferred. The 'grouping' is called 'consisting' and yes, consists can add up to an effectively bidirectional set with a unidirectional locomotive facing 'out' at each end, with either nothing in between, or unidirectional locomotives facing either direction in between, or with 'B units' (without cabs) in between. Hayttom (talk) 16:17, 13 March 2025 (UTC)

In my experience (which is in Europe), most trains are bidirectional, so there's no need for regular turning (only sometimes to equalise wear). Most trains here are for passengers. Trams may use balloon loops, as it's faster, and people try very hard to make them silent. For goods trains, moving the locomotive to the other end is usually sufficient. But there are cases where it's necessary to turn the entire train around, like when reversing a train with an observation balcony or a car (automobile) train, to make sure the cars face to the platform for easy unloading. Or the route is selected to give an even number of reversals (including the push back to the platform).

How much noise there is from the in and out running of the slack depends on the type of couplings. I understand that American couplings are noisy (and strong) and European couplings are silent (and have no slack). Wheel brakes (acting on the running surface) are noisy, disk brakes are not. The squealing noise from a tight turn results from the flanges touching the rails. Every train wheel has a threshold; only when the radius of curvature drops below the threshold, squealing begins. So this can be eliminated by making the loop large enough. Diesel locomotives make more noise than electrics, in particular when accelerating. Nobody uses steam any more (except some touristy applications).

So we have a lot of variables to consider. PiusImpavidus (talk) 09:12, 12 March 2025 (UTC)

(edit conflict) In my (subjective) experience the noise of North American trains is very different from European trains, so the answer probably not only depends on engineering details of the arrangement itself, but also on the make of the rolling stock being reversed.  ​‑‑Lambiam 09:21, 12 March 2025 (UTC)

My impression from OP's description is that they're talking about freight trains. These are of course not bidirectional, but also shouldn't need to be turned around entirely, hence my idea of simply putting the locomotive at the other end (track layout permitting, of course). --Wrongfilter (talk) 10:57, 12 March 2025 (UTC)

"Freight trains...are of course not bidirectional." Do you mean you can operate a freight train in push mode (rear locomotive) for yard operations, wye, etc. but not for regular mainline service? Are you thinking about a traction or other physics problem, or simply that an engineer in the last car wouldn't be able to see forward well enough to control it safely? DMacks (talk) 01:36, 13 March 2025 (UTC)

I meant bidirectional for mainline service, do I really have to spell that out? --Wrongfilter (talk) 06:40, 13 March 2025 (UTC)

Mostly a matter of visibility. For example, the driver must be able to respond to signals before the front of the train reaches them. That may be a bit hard if signals are visible from 300 metres and your train is 1000 metres long and you're driving from the back. In yards where such pushing is used, there may be a shunter on the front of the train, in radio contact with the driver or driving by remote control, but since there's no driving cab, this is illegal at mainline speeds. Alternatively, there may be repeater signals. PiusImpavidus (talk) 10:51, 13 March 2025 (UTC)

So today Wrongfilter will learn that push-pull trains can easily be done with a simple control car in front rather than a full loco. DMacks (talk) 02:25, 14 March 2025 (UTC)

Sigh, what is this? We're talking about freight trains, not passenger trains. Neither of these articles mentions freight trains. --Wrongfilter (talk) 06:22, 14 March 2025 (UTC)

You can make goods trains bidirectional by having a locomotive at both ends. With electrics that's often a waste of resources, but using the less powerful diesels you're likely to need multiple locomotives anyway. Of course, you want some way to remotely control the rear loco from the front one. That either means a data cable running the full length of the train (technically not so hard, but you have to agree on standard cables and connectors and apply those to all wagons on your continent) or some sort of wireless link, with all the difficulties that come with wireless links.

An interesting case of bidirectional goods trains (if I remember every detail correctly...): Some years ago a goods trains operator in the Netherlands wanted to run an intermodal train from Kijfhoek shunting yard to the Bad Bentheim border crossing to Germany. The selected (and shortest) route was Kijfhoek – Rotterdam – Woerden – Utrecht – Amersfoort – Deventer – Hengelo – Bad Bentheim. Go to your favourite map site to check the track layout. This route required reversing at Utrecht, close to the city centre. Authorities, not knowing anything about railways, had forbidden all shunting operations there with trains carrying hazardous materials. Moving a locomotive to the other end of the train is officially a shunting operation and intermodal trains could always carry a container with dangerous chemicals. The solution? The train departed Kijfhoek with a second locomotive, shut down at the rear of the train. At Utrecht, the driver shut down the locomotive at the front, walked to the other end of the train, started the other locomotive and continued his journey.

Some time later the route of the train was revised. Using the detour Woerden – Breukelen – Diemen Zuid – Weesp – Amersfoort, the reversal was gone, but with all those junctions in urban areas, it was probably riskier than the more obvious solution. PiusImpavidus (talk) 11:06, 13 March 2025 (UTC)

Locomotives are often placed at both ends of long freight trains and also often at a strategic point in between. This is called distributed power and uses wireless links. These have none of the difficulties the previous poster seems to imagine, whereas using a data cable would be far far far harder than they explain or seem to imagine, given that any North American freight car could find itself in the train. The connection that does run car to car is the existing air brake circuit, but this is already built-in whether there is distributed power or not. Hayttom (talk) 16:27, 13 March 2025 (UTC)

Lac-Mégantic_rail_disaster. 2A00:23C7:E53F:2901:C56C:8909:9074:5E46 (talk) 10:56, 14 March 2025 (UTC)

March 13

ozonolysis

1. Define ozonolysis and explain its significance in organic chemistry� 105.113.28.199 (talk) 13:19, 13 March 2025 (UTC)

Someone else might be able to provide a better answer, but in the meantime, see Ozonolysis. MediaKyle (talk) 13:22, 13 March 2025 (UTC)

And you forgot to say "Please". ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:04, 13 March 2025 (UTC)

Give him a break. He was quoting exactly from his homework assignment, question number and all. In this, he has succeeded admirably. :( -- Jack of Oz ^{[pleasantries]} 19:06, 13 March 2025 (UTC)

But he forgot to put his name at the top of the paper. Sorry, that's a zero. --Trovatore (talk) 19:11, 13 March 2025 (UTC)

Zero being a character in Beetle Bailey. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:57, 13 March 2025 (UTC)

Zero, also known as 'goose egg'. Eggs can be sterilized by ozone. Is this like a Wiki rabbit hole game? DMacks (talk) 02:30, 14 March 2025 (UTC)