Wikipedia:Reference desk/Archives/Science/2020 December 16

= December 16 =

Who's been nibbling my neeps?
My Swedes (I would call them turnips myself, but that's another story) have some cosmetic damage, visible as pale patches in the picture. Parts of the surface have been nibbled away by something. Their eating quality is unaffected. Any idea who is doing this? The allotment is in Sussex, England, UK. They were grown in a mix of fresh commercial compost and well-rotted manure. The underlying soil is chalky. DuncanHill (talk) 01:10, 16 December 2020 (UTC)
 * Might be a touch of Scab (Streptomyces scabies), better known for attacking potatoes but also affecting radishes, turnips (and other brassicae), carrots etc. If your plot has any soil condition variations (natural or induced), is the problem greater in drier and higher pH areas? {The poster formerly known as 87.81.230.195} 2.122.56.237 (talk) 03:24, 16 December 2020 (UTC)
 * I don't think it's common scab, while I have had that on some varieties of potato (now seems to be controlled by sulphuring the beds) the lesions on the turnips are more of the nature of the skin being removed. DuncanHill (talk) 20:39, 16 December 2020 (UTC)
 * My next-best guess would be slugs, possibly a species that prefers to remain underground rather than attacking the foliage. {The poster formerly known as 87.81.230.195} 2.122.56.237 (talk) 01:03, 17 December 2020 (UTC)
 * I agree it looks like slug damage - see this image. According to Scotland's Rural College (www.sruc.ac.uk), the pests that attack swede roots are slugs, cutworms (caterpillars of various moth species), and cabbage root fly larvae, but the damage caused by the last two are different to your example - SRUC have published a pdf called 'Pests of Swedes and Turnips - Their Management and Control', which should be google-able (I don't know how to link it directly). PaleCloudedWhite (talk) 22:14, 17 December 2020 (UTC)
 * Thanks I think that's it. DuncanHill (talk) 02:03, 20 December 2020 (UTC)

What are the kilos of man per kilo of plant ratios that will sustain life?
In a closed system where the oxygen only comes from the plants and the carbon dioxide only comes from the human(s).

What if food is given by a double airlock that always pumps air back to the side it came from so you don't have to eat the plants? Sagittarian Milky Way (talk) 08:11, 16 December 2020 (UTC)
 * You don't like vegetables? ←Baseball Bugs What's up, Doc? carrots→ 10:09, 16 December 2020 (UTC)


 * Although you probably won't find an answer to your specific question, Closed ecological system is one place to start your research. 107.15.157.44 (talk) 18:36, 16 December 2020 (UTC)


 * For an early treatment of the idea, you could watch Silent Running. ←Baseball Bugs What's up, Doc? carrots→ 19:06, 16 December 2020 (UTC)
 * A man consumes some 0.9 to 1.1 kg oxygen and produces some 2 kg CO2 per day. About 300 to 500 potted plants will produce that amount of oxygen given enough light but it is difficult to calculate how much CO2 they will bind in the process and they produce some CO2 anyway. As 2% CO2 in the air you breathe will kill you, it is not sure you will survive the hours of darkness. 2003:F5:6F18:ED00:40E1:C2AF:BF93:B804 (talk) 11:51, 20 December 2020 (UTC) Marco PB
 * So maybe eating the plants is very helpful as it allows you to consume more of your carbon and breathe the output of plants which haven't yet reached maximum size thus still net turning CO2 carbon into body atoms. Assuming your little biosphere is big enough to survive long but eventually corrected periods of net depletion of one gas or the other. More oxygen comes from photosynthesizing plankton than from trees so perhaps plankton with its different lifecycle would be easier to mini-biosphere with. If you can find a way to eat them. And with any indefinitely sustainable method you will of course need a way to turn urine and feces back into water and fertilizer and probably a humidity regulator that collects breath vapor so it doesn't build up till it condenses everywhere and then you have to painstakingly collect it to water the plants to take the place of rain as urine and poop water are less than water in (unless your biosphere is a continuous column thousands of feet high and produces rainclouds automatically) Sagittarian Milky Way (talk) 15:01, 20 December 2020 (UTC)

Ureter regeneration
Just how much of the ureter can be removed for the body to be capable of regenerating it? Futurist110 (talk) 23:08, 16 December 2020 (UTC)
 * As much ureter as a body could. Also this experiment is likely to cause a painful death or at least require a kidney donation. Sagittarian Milky Way (talk) 23:31, 16 December 2020 (UTC)
 * The human body can't survive with just one ureter, can it? Anyway, is there any tube in the human body that is capable of damaging other than one's vas deferens or one's epididymis that isn't overly harmful to oneself if damaged or destroyed? Futurist110 (talk) 00:48, 17 December 2020 (UTC)
 * Obviously the body can so survive, provided that the relevant kidney is also removed. (Many people live with only one kidney, sometimes without even being aware of their condition – see Renal agenesis.) {The poster formerly known as 87.81.230.195} 2.122.56.237 (talk) 01:10, 17 December 2020 (UTC)
 * Are there ever any cases where there is a ureter for one of the kidneys but not the kidney itself? Futurist110 (talk) 01:36, 17 December 2020 (UTC)
 * First return from websearching "Renal agenesis with ureter present" apparently says "Yes" (according to G∞gle's summary box). {The poster formerly known as 87.81.230.195} 2.122.56.237 (talk) 04:20, 17 December 2020 (UTC)
 * Interesting! Futurist110 (talk) 08:41, 20 December 2020 (UTC)