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December 9

Antarctic blue-green algae thrives in conditions on Mars?

From [1]

“ In 2012, Dr. De Vera showed that cyanobacteria – a phylum consisting of free-living bacteria – present on Earth for 3.5 billion years could survive several weeks in the "Martian chamber" without a problem.

He repeated his experiment for nine days with microorganisms recovered from Earth’s harshest continent – Antarctica.

They did not just survive, though, they thrived....

“From what we’ve seen, the results we’ve had, it would be possible to find life there, or terrestrial life, microorganisms could survive on Mars.

“It’s impressive, we never imagined these results, especially with more complex organisms.

“They are not bacteria, they’re organisms, which use photosynthesis.

“Life is possible on Mars, and Mars can be a habitat for organisms that live on Earth.”

”

Is the quoted characterization consistent with, "The fluorescence signal from photosynthetic pigments was differently preserved after UV irradiation, depending on the thickness of the samples" in [2]? The organisms which use photosynthesis survived, but did photosynthesis actually occur, i.e., was it still a viable process for the organisms? EllenCT (talk) 21:46, 9 December 2019 (UTC)

December 10

Is there a qualitative explanation for avoided crossing ?

So I have not been allowed to take quantum chemistry in my program due to silly bureaucratic rules based on academic caste. As such, I plan to teach myself the core ideas after finals. However, how does avoided crossing lead to resonance stabilization using qualitative frontier molecular orbital theory? I can't find any good sparknotes on this topic online. Yanping Nora Soong (talk) 00:32, 10 December 2019 (UTC)

Avoided crossing is a specific episode related to the non-crossing rule (two eigenvalues corresponding to orbital of the same symetry cannot cross even though the corresponding two diagonal matrix elements can cross, see Woodward–Hoffmann rules for context ). This discussion on state correlation and orbital correlation illustrates the occurrence of avoided crossing. An absolutely similar example of electrocyclic reactions is used in the FMOA article, so is still leaving it to you to establish a qualification. More succintly, see this State Correlation Diagram in a pericyclic reactions context. --Askedonty (talk) 22:21, 13 December 2019 (UTC)

Subsidence

Are there any famous examples of subsidence of structures built on pad foundation? Maybe houses? 2A01:4C8:28:AD02:404:9DC:2956:7D76 (talk) 21:32, 10 December 2019 (UTC)

Not sure exactly what pad foundation is, but the leaning apartment blocks of Santos might qualify. 93.136.71.134 (talk) 21:38, 10 December 2019 (UTC)

Here is a direct link to the leaning towers. Richard Avery (talk) 08:54, 11 December 2019 (UTC)

Left and right in pictures

When describing a picture of two people facing the viewer, one can use "left" and "right" either from the viewer's perspective, or the perspective of the people in the picture. Somewhere, somewhen, I read that the decision which to use is affected by the culture one comes from, but I can't find a suitable reference for this online. Can anyone help? Henry^Flower 21:37, 10 December 2019 (UTC)

Have you read about § stage directions? Nimur (talk) 21:50, 10 December 2019 (UTC)

Interesting! Though annoyingly the perspectives mentioned there for English and Arabic speakers respectively seem the opposite of my experience with pictures (i.e. that English speakers use the viewer's perspective, and Arabic speakers that of the person in the picture). Henry^Flower 22:16, 10 December 2019 (UTC)

Another anomolous example is the technical art and practice of blazonry in heraldry, that is, of describing the elements of a 'coat of arms'. This, which uses a vocabulary based on 12–15th-century Anglo-Norman French, describes the arms as from the point of view of the putative wearer or carrier (in the case of the shield) who is facing the viewer, so that for example the dexter side of the shield is on the left as the viewer sees it, and the sinister side on the right. {The poster formerly known as 87.81.230.195} 2.217.209.178 (talk) 04:39, 11 December 2019 (UTC)

The example is as expected considering that the shield is there for the benefit of its carrier. It's as understandable as the need to cut costs on decals explains why the pony prances backwards on the right hand side of Ferrari cars. DroneB (talk) 11:12, 11 December 2019 (UTC)

The shield benefits the carrier, but the blazonry is there for the viewer - the bearer can't even see it (and, if they do, ta da! the left is now the right after all). Matt Deres (talk) 15:28, 12 December 2019 (UTC)

December 11

River tributaries by discharge volume

I'm hoping to diagram a few river basins around the world. Ideally I'd like to include any tributary that meets a certain threshold—say 5% of the basin's total discharge. I'm currently using the Murray River as a trial. The article on the Murray–Darling Basin is helpful in understanding the sequence of the tributaries and their connections but does not contain discharge volumes. I've been looking for volumes just by tracing branches and opening lots of browser tabs. Some individual articles include discharge volumes in the infobox, but many others (most?) do not. One may reasonably suppose that larger rivers are likely to have more complete information available, but I suspect that assumption fails from time to time. Presently, I've traced 426 m³ of the basin's 767 m³ to tributaries discharging more than 30 m³, suggesting that the other 341 m³ is contributed by feeders below the threshold, but I don't have a sense if that's a good assumption, and I don't have an obvious way to check my work in case I missed a branch somewhere. Does anyone know of source that would make this kind of information-gathering easier? Thanks! —jameslucas ^{▄▄▄ ▄ ▄▄▄ ▄▄▄ ▄} 22:39, 11 December 2019 (UTC)

(P.S. I'd be open to using basin area instead of discharge volume if that made an appreciable difference in data-gathering ease. —jameslucas ^{▄▄▄ ▄ ▄▄▄ ▄▄▄ ▄} 23:28, 11 December 2019 (UTC))

Discharge varies over time, so unless every value you use for every one of the tributaries in the basin is some kind of average measure, or if they are all instantaneous values that were coincidentally collected at the exact same instant, there is no good reason to assume that the numbers should add up nicely. On top of this, stream- and river- discharge constitutes surface water flow - but over a large basin, an enormous percentage of the water volume is not surface-water. In many parts of the world, most water flow is underground. So when you look at stream gauge or discharge data, you should treat the values as a sort of reference-number that gives you an idea about the stream; but if you want to really do quantitative analytical study of the amount of water, you need a much more sophisticated methodology. The key takeaway, though, is pretty simple: water enters the rivers via tributaries, but water can also enter and exit the river in the vertical direction at every single portion of the basin, not only at the confluence of the surface streams. New water gets added or subtracted upwards and downwards - evaporation, precipitation, and groundwater charge- and discharge- into and out of the subsurface.

Also be sure to read hydrology and hydrogeology and groundwater flow.

Here's a pretty decent book cited by several of our articles: Groundwater Hydrology: Conceptual and Computational Models.

Nimur (talk) 23:47, 11 December 2019 (UTC)

Thanks, Nimur! The notion of water entering and leaving from underground makes sense but I hadn't considered it. Ultimately, my project is more artistic/symbolic than scientific, so I probably won't be delving into that level of detail until I have a bit more time to spare, but I'm definitely appreciative of the resources you recommended. For what it's worth, I was looking at average discharge and wasn't concerned about great precision. Since I asked my question, though, I started looking at the Yangtze, and I realized that English resources (here or elsewhere) for Chinese rivers are so underdeveloped that I can't see being able to take this strategy global anytime soon. I'll see if I can make it work with basin areas instead. Cheers! —jameslucas ^{▄▄▄ ▄ ▄▄▄ ▄▄▄ ▄} 01:08, 12 December 2019 (UTC)

I'm noting something I can't make sense of: The Lachlan River is a tributary of the Murrumbidgee River, but according to their articles' infoboxes, the rivers' basin sizes are nearly identical (84,700 km² and 84,917 km², respectively). Am I correct in thinking that this makes no sense since the basin of any river should include the basin of its tributaries and the basin of a tributary can't realistically be 400× larger than the river it feeds into? —jameslucas ^{▄▄▄ ▄ ▄▄▄ ▄▄▄ ▄} 02:36, 12 December 2019 (UTC)

Yes, those numbers seem suspicious. I also note that neither article cites a source for those data. It is possible that the numbers are somehow being misinterpreted from a valid authentic original source, but they are being repeated on Wikipedia without attribution so it's very hard to follow up or verify. It is also possible that those numbers are completely fictional - in other words, they may be the result of intentional vandalism to add incorrect numbers to our articles. Without a cited source, it's really hard to say with certainty.

This type of data-retrieval question exactly the sort of thing that a Wikipedia article is very bad at. It's difficult for our editors to verify who added the numerical values, and whether those values are accurate and correct.

If you want to find such numerical data, you almost surely want to find a reliable peer-reviewed source that is not authored and curated by a community of anonymous volunteer editors (... like us). Our Wikipedia articles can give you a good introduction that is largely correct - and our editors can and will remove "obviously-wrong" information - but when it comes to quoting a specific numeric value, the process of article-editing that we use around here is just not well-suited to keeping such data consistent, correct, and current. We manage to make Wikipedia function very well as an encyclopedia - but we do not have the capacity to make Wikipedia into a very good data-almanac. In fact, it's a terrible very very bad data-almanac that frequently contains wrong, stale, or maliciously-vandalized numerical data.

The good news is, there are lots of better alternatives!

For example, Geoscience Australia (a department of the Australian national government) publishes a catalog of data products. They also publish national-scale maps of river basins and catchments; and if you use their search-engine, you can find loads of more detailed specific information about specific basins and catchment areas. They also have a downloadable GeoFabric database from which those maps were produced. An enthusiastic and skilled individual can read the how-to tutorials to do things like calculate the basin drainage area using the database - but it is going to require a little bit of effort (and a basic familiarity with industry--standard tools, including ArcGIS software).

Overall, that data might be a little "less-conveniently-packaged" than our Wikipedia articles, but it almost surely is of much higher quality: it is curated by experts and it is more likely to be consistent, correct, and current.

Waxing philosophically - the reason that those sources are more reliable is not simply because the numbers were provided by experts; nor because the numbers are provided by a government agency. Those sources are more reliable because every line-item of data is accompanied by detailed thorough documentation that expresses where the numbers came from, and how to interpret them, and what pitfalls you need to be aware of when you use those numbers. There is, so to speak, a deeper chain of accountability that explains the provenance of each element of the data. Without the context provided by the documentation, those data would be otherwise-arbitrary numerical values of dubious merit.

Real scientists don't just copy-paste their numbers from a convenient list - they always check the work! Now, because you're seeking the numbers for "artistic and aesthetic" purposes, we might be able to find some kind of summary that somebody else has already done - like the map and list of data tables that I linked to earlier - but I'm not sure it's detailed enough for what you wanted.

Nimur (talk) 04:23, 12 December 2019 (UTC)

A look at this article highlights the difficulties of describing flows in anything like fixed numbers. The Darling ran dry this year. HiLo48 (talk) 23:05, 14 December 2019 (UTC)

December 12

What was the first ICE >1797 cc displacement ever made that could reach 10,000 rpm?

Redline rpm if it had one. Sagittarian Milky Way (talk) 02:58, 12 December 2019 (UTC)

What does the Immigration service have to do with Revolutions Per Minute? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:14, 12 December 2019 (UTC)

Internal combustion engine. Sagittarian Milky Way (talk) 04:21, 12 December 2019 (UTC)

• No idea, but I bet it was a 1950s, maybe 1960s, Formula One engine. 10,000 is pretty fast for an engine that size, even now. BRM built a number of engines which revved that high, although the formula limit was 1,500cc, so under your limit. However they also built at least a few (the H-16 for one) which followed a rule change one year and allowed up to 3,000 for non-supercharged engines. They pretty much doubled the previous engine and used that, and as it was the same size (they coupled two flat-8s into a H-16), they still revved beyond 10,000 rpm. Andy Dingley (talk) 15:44, 12 December 2019 (UTC)

Rotary Wankel engines have highest r.p.m. capability, for example in 1957 a prototype NSU DKM=Drehkolbenmotor was tested to 17000 rpm. Small displacement Wankels then appeared in vehicles from Citroen, Hercules, Norton and Van Veen (see Comotor), and Mercedes-Benz C111 concept cars with M950F engines had up to 2.4 L four-rotor Wankels by 1970. Among reciprocating engines, 2 stroke engines don't have the camshaft, timing chains, valves, or rocker arms that limit the speed of 4-stroke engines. Small 2-strokes that reach 20 000 rpm have appeared in extreme motorcycles such as Suzuki RP68. Among Formula One 4-stroke engines the Cosworth DFV 2,993 cc exceeded 10,000 rpm during the 1980s. Engines at the time were limited to around 12,000 rpm due to the traditional metal valve springs used to close the valves. DroneB (talk) 16:18, 12 December 2019 (UTC)

Non helical models of DNA structures, sub-title Experimental studies of circular DNA structure

I have made some edit on the Non helical models of DNA structures, sub-title Experimental studies of circular DNA structure. I tried to add a reference［37］ to it but failed. Can you help me?<ref> — Preceding unsigned comment added by Ycxu2019 (talk • contribs) 23:00, 12 December 2019 (UTC)

Shouldn't you leave that on the talk page for that article? --OuroborosCobra (talk) 23:20, 12 December 2019 (UTC)

(Non-helical models of DNA structure). The opening <ref> tag was missing; I have fixed it. Please note WP:SELFCITE. catslash (talk) 00:51, 13 December 2019 (UTC)

• I have made some edits to the references and also opened a discussion at Talk:Non-helical models of DNA structure#Work from Xu, Y. C. about some concerns. Any and all comments etc welcome. Thanks, EdChem (talk) 04:10, 13 December 2019 (UTC)

December 14

Testicular Damage Question

How much damage is there going to be to human male testicles and the tubes next to them (epididymis, vas deferens, spermatic cord, et cetera) if they are squeezed extremely tight nonstop for several minutes or maybe even a little bit more than that?

Also, is any of this damage actually going to be permanent? Futurist110 (talk) 02:45, 14 December 2019 (UTC)

Depends on the ischemia caused, generally not much. Should check with the urologist for examination. — Preceding unsigned comment added by 196.194.226.237 (talk) 10:53, 14 December 2019 (UTC)

What would be required to create a large amount of ischemia? Futurist110 (talk) 18:08, 14 December 2019 (UTC)

This is bordering on Selfharm.

Yes, see your doctor if you're concerned. But why would you want to do that anyway? ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:22, 14 December 2019 (UTC)

An attempt to trigger testicular pain in order to get approved for a bilateral epididymectomy is one possibility. Futurist110 (talk) 18:08, 14 December 2019 (UTC)

Ischemic injury to testis is indication for orchiectomy not epididymectomy.

It sounds like you're asking us to help you commit fraud. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:11, 14 December 2019 (UTC)

If dinosaurs became extinct due to asteroid or extreme cold then how other animals survived

Dinosaurs are shown as very strong. If the reason which made them extinct that would have erased other life forms also. — Preceding unsigned comment added by Abiyt (talk • contribs) 05:17, 14 December 2019 (UTC)

Nothing personal, but this is basically argument from incredulity. Also, some dinosaurs did survive; now we call them birds! Dinosaurs are/were enormously diverse, while "strong" is a very vague description. "Strength" doesn't have much to do with starving to death because the planet is darkened by an impact winter, which is what scientists now generally agree happened at the Cretaceous–Paleogene extinction. No plants growing meant things dependent on them, directly or indirectly, starved to death. The life that survived either was able to make do with what remained, as with detritus-feeders like crocodilians, or wasn't dependent on plants for primary production, like hydrothermal vent dwellers, which don't give a toss what happens way up at the surface. --47.146.63.87 (talk) 08:12, 14 December 2019 (UTC)

Practically all groups of animals suffered extinctions at KT boundary. For instance, over 90% of all mammals went extinct. Ruslik_Zero 20:36, 15 December 2019 (UTC)

One theory is that anything above ground was toast by way of extreme heat. Only things that were underground, perhaps in burrows, or under water, survived. Those big dinosaur animals were cooked or starved. Graeme Bartlett (talk) 20:34, 15 December 2019 (UTC)

If "strength" mattered, the Northern white rhinoceros wouldn't be effectively extinct. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:29, 15 December 2019 (UTC)

• Even today, animals rarely become extinct because they've all been killed off, but rather because their environment has been disrupted to such a level that their particular habitat is no longer viable. This may be a lack of food sources, or a lack of whatever else they depend upon for survival. That could be as simple as an adequate ambient temperature, if we follow a (now somewhat challenged) view of dinosaurs as cold-blooded. Andy Dingley (talk) 22:31, 15 December 2019 (UTC)

Different features provide different advantages at different times. And being big, although it's a plus in a confrontation, it's not a desirable trait when you food is scarce. C est moi anton (talk) 06:11, 16 December 2019 (UTC)

Kinematically coherent?

Please define the phrase "kinematically coherent" in laymans terms with a view to verifying its use on Monoceros Ring ~ R.T.G 06:52, 14 December 2019 (UTC)

It means the pieces move together (not together meaning "towards each other", but the "as a set" sense...all having the approximately same speed) rather than dispersing.[3] So in that article, one option is that there was some previously-existing ring ("progenitor") that is in the process of evolving into the Monoceros Ring, whcih would presumably mean their motions are not truely independent of one another. The other option is that they are two separate rings, each of which has its own independent motion (but of course any one ring has a unified motion as a ring...each is "kinematically coherent" itself else it would not remain in a ring formation). DMacks (talk) 08:35, 14 December 2019 (UTC)

Understanding but failing to describe it. It's sort of jargon, but if I can't describe it without a pamphlet... I'm pretty sure there's a word to do with connection or origin... Mind keeps saying "synchronised parallel motion" but that's not even accurate. Thanks DMacks o/ ~ R.T.G 10:19, 14 December 2019 (UTC)

Something about "the particles that comprise the ring remain together as the ring moves, rather than dispersing or exchanging with an adjacent ring"? DMacks (talk) 10:24, 14 December 2019 (UTC)

No it's about the possible relation to the origin. If it is tied in motion to one thing or another. Not linked motion, but trajectory linked because they share a common origin. That's probably accurate but doesn't fit the sentence. It's says in my words, the study of the trajectory may suit a theory about another galaxy in "kinematic coherence". And I was left going... in... in... in... trying to get a commonly used phrase out. I wanted to put a word in parentheses (brackets) like that. Awk, if it's accurate and I can't be certain, I'm sure it will be okay :P~ R.T.G 11:45, 14 December 2019 (UTC)

How about ' a group of particles whose motion can be described using one 3 dimensional translational vector and one 3 dimensional rotational vector' , ie they behave as if they were a point cloud on a rigid body. Greglocock (talk) 19:16, 14 December 2019 (UTC)

"Translational" is quite technical in this context. One of the things it requires, apparently, is the motion to be in a non-rotational manner, which just isn't going to apply to the Monoceros. According to Wikipedia, "coherence" in physics is always about quantum studies, but "kinematically coherent" gets 4,000 hits on Google, seeming to be used just as widely in astro physics in that context, so a change is up in that area. ~ R.T.G 07:08, 15 December 2019 (UTC)

which type of wood this is ?

This wood was bought from Sargoha,Punjab, Pakistan. Which type of wood it is? It some thorn-like structure under the bark. https://i.ibb.co/4ggphWz/20191213-151627.jpg https://i.ibb.co/StQpFg6/20191213-151623.jpg https://i.ibb.co/p25txZc/20191213-151503.jpg https://i.ibb.co/d0ZCSRY/20191213-151449.jpg — Preceding unsigned comment added by 196.194.226.237 (talk) 10:51, 14 December 2019 (UTC)

December 16

Statistics: What causes what distribution?

I get that if you throw a handful of dice, you'll end up with a normal distribution. Could someone suggest literature matching process/phenomenon to expected distribution? (not only how to statistically analyze the resulting distribution) --C est moi anton (talk) 06:20, 16 December 2019 (UTC)

A book that will give you lots of real world examples of distributions is "Statistical Procedures for Engineering, Management, and Science" by Leland Blank. It has a section called "Level Two: Distributions and Their Uses". The section contains several chapters, each on a different distribution, and several examples within each chapter. The examples are fairly specific, rather than general phenomena, so it might not be exactly what you are looking for.--Wikimedes (talk) 07:46, 16 December 2019 (UTC)