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November 6

Pornography addiction in animals

Has any scientific research ever been conducted showing that non-human animals are capable of addiction to pornographic imagery, in the same or similar manner as mice have been shown to be capable of addiction to cocaine, in that they will prefer cocaine over food and refuse food? 104.171.53.110 (talk) 23:44, 6 November 2024 (UTC)[reply]

I'm not sure there is unambiguous evidence that mere imagery can elicit sexual arousal in any non-human animal species. --Lambiam 08:01, 7 November 2024 (UTC)[reply]

"Unambiguous evidence" sounds like the challenge. We do have an article about panda pornography if we're willing to weaken the standard. And rhesus like to look at photos of certain body-parts of the opposite sex of their species (see Animal sexual behaviour#Others for ref). I assume the male researchers involved in that study made plenty of "look at this picture of macaque!" jokes. DMacks (talk) 08:44, 7 November 2024 (UTC)[reply]

Somewhere in one of our journals is a study on turkeys. Male turkeys get excited and attempt to mate with anything that makes them think it is female. The researchers began with a wooden female turkey and eventually ended up with a wooden female turkey head on a stick and the males still attempted to mate with it. If it is of interest, I can see if it is still in our collection and get a better reference. It isn't a photo of a turkey, but it is still an artificial substitute for a live turkey. 68.187.174.155 (talk) 18:26, 7 November 2024 (UTC)[reply]

They just gobble, gobble, gobble it up. Clarityfiend (talk) 01:06, 8 November 2024 (UTC)[reply]

Anyone wanna help me develop a RealHen? DMacks (talk) 04:46, 8 November 2024 (UTC)[reply]

November 8

Street lights, rain drops and windows

A few nights ago it was pouring down with rain. I looked out a window to take a look, and I noticed that really beautiful patterns of light appeared as I put my eyes right in front of rain drops that were in front of a street light. The rain drops had interesting 'arms' surrounding them, but the most important part I noticed was that there were so many black lines covering the entirety of the drops.

I was able to take a picture of them with my phone, but unfortunately most of the the lines do not appear in the photos. You can see some on the sides but most of them are missing.

What caused these lines to appear?

―Panamitsu (talk) 05:08, 8 November 2024 (UTC)[reply]

See Caustic (optics). --Lambiam 09:37, 8 November 2024 (UTC)[reply]

The repeating black lines are an example of Newton's rings. They occur due to internal reflections in a thin wedge of fluid and are most apparent when the source light is monochromatic e.g. yellow sodium light. The article shows a more reliable way to view the rings using a thin convex lens than relying on chance raindrop spreading. Philvoids (talk) 10:49, 8 November 2024 (UTC)[reply]

Yes, can confirm that this is what the lines looked like, although they were not as round as in the article's images. Thanks. ―Panamitsu (talk) 22:11, 8 November 2024 (UTC)[reply]

November 9

Black Body emissive power in medium

The black body emissive power in a medium $E_{m}$ is equal to the product of the square of its refractive index $n$ and the emissive power in vacuum $E_{v}$ with the formula:
$E_{m}=n^{2}E_{v}$ .
What does this mean in terms of the energy emitted, respecting the principle of conservation of energy and in the case where the energy is emitted in a vacuum, then enters a medium with refractive index $n$ ? Malypaet (talk) 23:16, 9 November 2024 (UTC)[reply]

Power is energy emitted over time. So energy is conserved as it is emitted more slowly. Heat energy turns into electromagnetic energy. Graeme Bartlett (talk) 10:15, 11 November 2024 (UTC)[reply]

Yes, but here, if you use the SI units in

Joules\cdot s^{-1}\cdot sr^{-1}\cdot m^{-2}

for emissive power as radiance, you have

E_{m}>E_{v}

. So, to conserve energy, you cannot use only the velocity for power, as you suggested. Malypaet (talk) 23:31, 12 November 2024 (UTC)[reply]

November 10

What is a pipehead dam?

I've seen various things described as a "pipehead dam" (common noun), as well as some specific instances of dams named "... Pipehead Dam", eg Serpentine Pipehead Dam, which is separate to Serpentine Dam. I gather from the text of Serpentine Pipehead Dam that a pipehead dam is a smaller dam fed from a larger dam, with the smaller (pipehead) dam then feeding water into the pipe into the water supply system - but I cannot find anything (including with a Google search) that specifically says that. Mitch Ames (talk) 01:03, 10 November 2024 (UTC)[reply]

Wow! This was hard to hunt down. Deep in the results for probably the same set of searches you did, I finally found on page 77 of [https://sitecore9-cm-prod.watercorporation.com.au/-/media/WaterCorp/Documents/Our-Water/Regional-Water-Supplies/water-forever-south-west-final-report.pdf]: "Pipe-head dam — a diversion dam that takes streamflow

from the catchment to another dam for storage." --jpgordon^{𝄢𝄆𝄐𝄇} 01:22, 10 November 2024 (UTC)[reply]

That definition appears to be the reverse of what the Serpentine articles say. The articles say water goes from main dam to pipehead dam, but the Water Corp definition suggest the water goes from pipehead to another (main?) dam. Mitch Ames (talk) 10:01, 10 November 2024 (UTC)[reply]

The point that might not necessarily come from the easy picking of the water authority or google online materials, is that in the history of the dams, the water can be moved either from the main dam to the pipehead, or vice versa - and in turn can also be distributed to other parts of the system, there is no one way only part of the system, maybe not easily found online but nevertheless the current water corp web space is very poor on the intracies of the dynamics of the water supply system. There could well be a range of security issues attached to the lack of information . JarrahTree 10:55, 10 November 2024 (UTC)[reply]

...for the over two centuries that pipe head dams have existed? --jpgordon^{𝄢𝄆𝄐𝄇} 16:37, 10 November 2024 (UTC)[reply]

The higher the pitch of the instrument the longer the bow: why?

As everyone has probably noticed, the violin has a longer bow than the viola, which has a longer bow than the cello, which has a longer bow than the double-bass. Why? I'm guessing a given length of bow (irrespective of the instrument) takes the string through a given number of vibrations. Therefore to make the string vibrate for a given amount of time at a higher frequency requires more bow length. But is this correct? Another consequence would be that no matter what the instrument the bows make the string vibrate for roughly the same amount of time and that the violin requires a higher bow speed than the viola which requires a higher bow speed than the cello which requires a higher bow speed than the double bass. Again, is this correct? 178.51.16.158 (talk) 08:15, 10 November 2024 (UTC)[reply]

To make the string vibrate with a nice sound, there has to be sufficient (but not too much) friction between the bow and the string, which requires the bow to move at the same speed or just slightly faster than the top speed of the vibrating string, 2π times the product of amplitude and frequency. So higher frequencies at a given level of dynamics require a higher bow speed. --Lambiam 09:17, 10 November 2024 (UTC)[reply]

Ok. But leaving aside variations of the amplitude of the vibration, of the tension of the string, of the tightness or looseness of the bow (which the player can adjust), of the mass of the string and of the bow, of the thickness of the string and of the material it is made of, of the thickness of the bow, of the length of the string, of the force exercised by the hand, of how carefully the player has rubbed his bow with rosin, of the quality of the rosin, etc. etc. is it nevertheless the case that (things being roughly equal) to sustain a string's vibration at a higher frequency for a given unit of time requires more bow length? Clearly in practice there wouldn't be a linear relation between increase in frequency and increase in length. 178.51.16.158 (talk) 17:12, 11 November 2024 (UTC)[reply]

(Only) slightly pertinent to this query, you might be amused by Kingsley Amis's 1971 novel Girl, 20, in which a would-be avant-garde classical composer and violinist performs a controversial concert with rock musicians (an actual thing at the time, see for example Concerto for Group and Orchestra). Someone has secretly greased both his violin bows, but he impresses with his technical skills (though not with his actual music) by borrowing and using a double-bass bow. {The poster formerly known as 87.81.230.195} 94.7.95.48 (talk) 17:54, 10 November 2024 (UTC)[reply]

The articles about Bow (music) and the archetien who makes them say little about bow length. My survey below does not support the OP's observation. Lengthwise the bows for viola, violin and cello seem nearly interchangeable. The wide variation in longer bows for the double bass is due to the sitting players' preferences and arm lengths.


                |  Viola |   Violin |  Cello  |  Double bass
                |        |          |         |
bow    strings  |        |          |         |
cm   LOW    TOP |        |          |         |
----------------+--------+----------+---------+-------------
80   196    659 |   GE   |          |         |   x
79     .      . |        |          |         |   x
78     .      . |        |          |         |   x
77     .      . |        |    CA    |         |   x
76     .      . |        |   x      |         |   x
75     .      . |  x     |   x      |         |   x
74     .      . |  x     |          |   CA    |
73     .      . |        |          |  x      |
72    41     98 |        |          |  x      |    EG
 cm    Hz     Hz

Philvoids (talk) 12:15, 11 November 2024 (UTC)[reply]

Your chart would make the relationships clearer if Violin were in the first column, reflecting the order of relative sizes (hence string lengths and usual ranges) of the instruments. I can see a clear correlation between increasing size and decreasing bow length for the first three instruments. The double-bass may be anomalous because, unlike the other three, it is usually played standing.

I am also puzzled by your quoted figures, as my full-sized violin bow is only 65cm (ribbon length), and I am sure I have seen double-basses played with bows less than 50cm. {The poster formerly kown as 87.81.230.195} 94.7.95.48 (talk) 17:53, 11 November 2024 (UTC)[reply]

November 13

Light patterns

When I stare at a ceiling light and use my fingers to very slowly close my eye lids I see a weird pattern emerge. It looks like floaters that are covering my entire vision. I must also add that you can also see it (but with lesser detail) if you position your phone so that you can see the sun's reflection in the camera, and then you bring the reflection right in front of an eye.

What am I seeing? I'm guessing it is something inside my eyes because it looks so much like floaters. ―Panamitsu (talk) 10:38, 13 November 2024 (UTC)[reply]

It sounds like you should ask your eye doctor. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:33, 13 November 2024 (UTC)[reply]

November 14

Tau propagation

Create redirect Tau propagation to ~~Tau_protein#Tau hypothesis of Alzheimer's disease~~ which section of Tau protein? ExclusiveEditor _{Notify Me!} 20:12, 14 November 2024 (UTC)[reply]

It is a controversial hypothesis that cannot be dealt with with a simple redirect. --Lambiam 05:38, 15 November 2024 (UTC)[reply]

November 15

Why are Koalas vulnerable to extinction

Hi. I was wondering why Koalas are vulnerable to extinction unlike Kangaroos, which are way more common, and both animals are found in Australia. Please let me know. Thanks. 2605:B100:142:A3B7:1D63:4EBE:694C:7BCA (talk) 04:22, 15 November 2024 (UTC)[reply]

The article has some information on it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:54, 15 November 2024 (UTC)[reply]

Habitat loss, especially lack of connected habitats, chlamidia, overcrowding, dogs. I doubt they are anywhere near extinct. Greglocock (talk) 05:17, 15 November 2024 (UTC)[reply]

It might have been quicker to Google your question - this was one of the first results; Threats To The Koala. Alansplodge (talk) 11:44, 15 November 2024 (UTC)[reply]

Kangaroos are more flexible in what they eat, and can move large distances faster. But koalas are cuter and so have more public awareness and are used as the poster animal, like giant pandas. Graeme Bartlett (talk) 23:52, 15 November 2024 (UTC)[reply]

Admiral Nakhimov

In the time leading up to the shipwreck in late August 1986, is it known whether Captain Victor Tkachenko of the Petr Vasev had been transferred there from a smaller ship? Because I've read an article a while ago in Science et Vie (the Russian version) about the human factors in that disaster, and this would be the only conclusion which would make any sense! 2601:646:8082:BA0:CD5E:73B7:6DF6:2CF6 (talk) 14:50, 15 November 2024 (UTC)[reply]

I think the question is better suited at WP:RDH. ExclusiveEditor _{Notify Me!} 20:56, 16 November 2024 (UTC)[reply]

Maybe RDM, but not RDH -- I avoid that one like the plague, it's full of America-hating terrorists (or at least it was on the few occasions when I actually bothered to look at it)! 2601:646:8082:BA0:CD5E:73B7:6DF6:2CF6 (talk) 03:19, 17 November 2024 (UTC)[reply]

Why don't plants photosynthesize efficiently?

Photosynthesis is 6% efficient in green plants, 20% in solar panels. I see hints that it's more efficient in red algae, but I can't find a figure. They need to be efficient because they live in low light environments. There's a note here at Artificial_photosynthesis#Some_advantages,_disadvantages,_and_efficiency which says photosynthesis is typically 1% efficient! What's up with that? Something about not having enough CO2 around in the air to have any use for the energy? I found this article which says For the cell, a steady input of electrical energy coupled to a steady output of chemical energy is best: Too few electrons reaching the reaction center can cause an energy failure, while “too much energy will cause free radicals and all sorts of overcharging effects” that damage tissues, but that seems to boil down to "the cells can't do it". Card Zero (talk) 20:54, 15 November 2024 (UTC)[reply]

Evolution doesn't necessarily aim for perfection, just for survival. If that 6 percent is good enough for survival, there would likely be no evolutionary pressure to do it "better". ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:55, 15 November 2024 (UTC)[reply]

Trees compete for light, so there's some pressure to grow faster, isn't there? Card Zero (talk) 23:15, 15 November 2024 (UTC)[reply]

If you want to compare solar panel effiency, you should compare production of a chemical like glucose from carbon dioxide using electricity. Or should we allow any other reduced and useful carbon compound. As plants do not just produce electricity. Graeme Bartlett (talk) 23:23, 15 November 2024 (UTC)[reply]

Photosynthesis in plants can be very efficient under the right conditions. For instance, from photon to hydrogen/ATP it is nearly 100%,because the difference to really 100% is what destroys the chlorophyll. And replacing destroyed chlorophyll is costly, energywise and sometimes it even costs magnesium. Therefore that part is developed to maximize efficiency. Another goal is in the development of the carbon dioxide capture. For this one must know that chemical reactions with gases are very dependent on the pressure of the gases. Even the direction, that is if it's exothermic or endothermic, depends highly on the pressure. If RuBisCo would be faster the carbon dioxide could not come fast enough onto the site of enzymatic activity and would therefore drop in pressure there. Which in turn would drive the demand for energy up in this pathway. To overcome the RuBisCo-limit the C4 plants were developed. But they have other deficiencies, where they additionally spend energy to capture carbon dioxide for storage, and don't get it back at the RuBisCo.

Generally plants have too much energy for the amount of water and, most important, carbon dioxide, to synthesize sugar. Some hydrogen has to be dumped into the production of Ethen and Latex or other hydrocarbons. Of course, the energy for this is typically not counted towards the efficiency of photosynthesis. Moreover some ATP is simply hydrolysed for heating. Or for regeneration of ADP. Whichever is needed where this takes place.

For comparison there exist bacteria where chemical reactions are driven by 1/16th of a proton, that is 1/64 ATP-Unit. That only works with a large Quantum state in a superposition. If someone would want to maximise the efficiency of the photosynthesis, the recipe is there for the taking. But think of the side effects! 176.2.78.14 (talk) 06:02, 16 November 2024 (UTC)[reply]

For this one must know that chemical reactions with gases are very dependent on the pressure of the gases. Even the direction, that is if it's exothermic or endothermic, depends highly on the pressure. If RuBisCo would be faster the carbon dioxide could not come fast enough onto the site of enzymatic activity and would therefore drop in pressure there.

Does this mean that plants photosynthesize more efficiently in environments with elevated air pressure? Can you recommend any resources for learning more about that? Thank you! -- Avocado (talk) 14:21, 16 November 2024 (UTC)[reply]

What about near volcanos?

Are there specialized plants growing in carbon dioxide rich environments that photosynthesize faster? Card Zero (talk) 12:42, 16 November 2024 (UTC)[reply]

No. I heard there are only a few places where there is consistent outgassing of CO₂ and yes, plants grow faster there. The thing is, plants are so starved for CO₂ that increasing CO₂ concentration instantaneously leads to increased sugar production. We think that the current photosynthesis evolved in a time when the atmosphere was like Venus's with perhaps 100 times the partial pressure of CO₂. Even now, you can put a houseplant in a pure CO₂ atmosphere in a glass vessel, and it does great. Another way of putting this is that there can be no natural selection for specialization in growing in a "carbon dioxide rich environment" since that would entail getting worse at using CO₂. Abductive (reasoning) 21:07, 16 November 2024 (UTC)[reply]

Thermometer thermal mass

I'd like to measure the air temperature in a room, outdoors, etc. Ideally by bringing the thermometer, turning it on if it is electronic, and looking at it. All thermometers that I've tried take several minutes to settle, which is annoyingly long. Is that inherent? Are there quicker ones? Don't want to spend a fortune, but "premium" is ok. Thanks. 2601:644:8581:75B0:0:0:0:2CDE (talk) 22:12, 15 November 2024 (UTC)[reply]

For an expensive high-tech solution use tunable diode laser absorption spectroscopy which should measure the temperature in the gas, rather than waiting for it to conduct into a detector. see https://www.yokogawa.com/solutions/products-and-services/measurement/analyzers/gas-analyzers/tunable-diode-laser-spectrometer/#Overview for a product. Graeme Bartlett (talk) 23:45, 15 November 2024 (UTC)[reply]

a really cheap way to go at it would be Resistance thermometer of course in Four-wire configuration. If the coil is very short, which is possible in four wires, then it will get the temperature in under a second. 176.2.78.14 (talk) 01:36, 16 November 2024 (UTC)[reply]

Thanks both, the resistance thermometer approach sounds promising. The tunable laser page says "request a quote" which means "too expensive for me to think about". 2601:644:8581:75B0:0:0:0:2CDE (talk) 02:45, 16 November 2024 (UTC)[reply]

An infrared thermometer retails at around USD 10, and reacts in less than a second from when you press the button. It doesn't measure air temperature but if you can assume your walls/floors/furniture/etc are about the same temp, it'll work. 85.76.117.61 (talk) 15:45, 16 November 2024 (UTC)[reply]

I have one but it is not very consistent between surfaces, and the air temperature can change faster than the furniture temperature. I guess it is better than nothing. Thanks. 2601:644:8581:75B0:0:0:0:2CDE (talk) 02:13, 17 November 2024 (UTC)[reply]

November 17

A lead zeppelin is your stairway to heaven?

In terms of fatalities per passenger-mile, and excluding combat losses during World War 1 (but including accidental losses during the same time period), which airships were more dangerous to fly in, those filled with hydrogen or with helium? I'm aware of the argument that helium-filled airships have a narrower flight envelope, which causes them to crash more often -- but, on the other hand, the flammability of hydrogen often had the effect of turning an otherwise survivable crash into one which is fatal for everyone on board, and also created the danger of explosion from lightning strike -- so between these two dangers, which one was the greatest? 2601:646:8082:BA0:CD5E:73B7:6DF6:2CF6 (talk) 03:41, 17 November 2024 (UTC)[reply]