Wikipedia:Reference desk/Archives/Science/2021 November 20

= November 20 =

Best cure (anti)mony can buy?
In Egypt scorpions attack (sic), it says "According to Egyptian media, large doses of antimony have been delivered to medical centers ..." Why? I can't find anything that suggests that it can alleviate or cure scorpion stings. Clarityfiend (talk) 09:14, 20 November 2021 (UTC)
 * The news reports that I've checked (the ones linked to in the article as far as they are accessible to me) talk about "anti-venom", not antimony. --Wrongfilter (talk) 09:52, 20 November 2021 (UTC)
 * Tartar emetic an antimony compound can treat some parasitic diseases, but not scorpion stings. Note that we have a growing collection in Category:Scorpion toxins. Graeme Bartlett (talk) 10:24, 20 November 2021 (UTC)
 * Hah! Thanks. Clarityfiend (talk) 01:04, 21 November 2021 (UTC)

Train of thought
Greater Anglia's leaflet New trains are here says

"They are also fitted with state-of-the-art technology which allows us to spot faults before they occur, so we can be better at preventing break downs."

How do they manage that? 2A00:23C5:C710:BC01:45B:4D79:A7CB:CBD1 (talk) 18:06, 20 November 2021 (UTC)
 * It sounds like e.g. systems that notice wear on a component and flag it for maintenance, instead of waiting for it to actually fail. 2602:24A:DE47:B8E0:1B43:29FD:A863:33CA (talk) 18:11, 20 November 2021 (UTC)


 * See Predictive maintenance. {The poster formerly known as 87.81.230.195} 90.205.225.31 (talk) 20:04, 20 November 2021 (UTC)


 * Perhaps they should have said "allows us to spot potential faults before they occur". Once you've spotted a fault, it has already occurred. --  Jack of Oz   [pleasantries]  22:58, 20 November 2021 (UTC)
 * Defect detectors are not intrinsically new technology either. DMacks (talk) 04:12, 21 November 2021 (UTC)


 * A Google search brought up the Trimble R2M remote diagnostic system which is used by Greater Anglia. Alansplodge (talk) 09:23, 21 November 2021 (UTC)
 * That flyer contains this sentence: "The data from the system is used to identify failures that will occur if they are not addressed." On close reading, it implies the use of crystal-ball diagnostics flagged by Jack of Oz in the sentence quoted in the original question. What should be addressed are of course the issues that may lead to failures – addressing failures includes such things as filling the well after the calf has drowned. The four-page flyer does a fine job in expounding in more than 2,000 words how much the Trimble R2M remote diagnostic system has improved performance for Greater Anglia, but none of these words is used to identify the nature of the data collected, nor how it is used for the timely identification of issues that may lead to failures. --Lambiam 11:42, 22 November 2021 (UTC)

Colour reproduction index (CRI) - will colours that match under high CRI light also match under low CRI light?
To check my understanding of CRI for light sources: although colours that appear to be equal under low CRI light might not do so under high CRI light, would it be possible for colours that are equal under theoretical 100 CRI light to not match under low CRI light? Or if the match under 100 CRI, must they necessarily match under any lower CRI? I have issues selecting thread to repair my clothes only to find out that under a different light, the thread no longer appears to match. My hope is that if I match the colours under a fancy light then they must match under any other light. --88.111.13.16 (talk) 19:30, 20 November 2021 (UTC)
 * I think you mean Color rendering index. Yes, it would be possible for them to not match even though the CRI values were the same (I think). As I understand it (and I may be wrong), two different lights that have the same CRI value of, say, 70, may both render the "true" (CRI 100) colour (excuse my BrE spelling) of an object with only 70% fidelity (this figure is an oversimplification, the maths are complicated), but they may have different colour spectra to each other, so those two equally unfaithful renderings may look different. The criticism section of the linked article alludes to this, though in more technical language and with additional factors mentioned.{The poster formerly known as 87.81.23.195} 90.205.225.31 (talk) 20:00, 20 November 2021 (UTC)
 * If you have a thing that only reflects green light and matches a leaf in 100 CRI light the thing will look black when lit by a hydrogen light bulb but the leaf should be magenta or purple. If I had to match without trying more than one lighting condition and without knowing more about your thread reflectance spectra, how often your clothes are in candlelight/sun/blue party light/high pressure sodium etc lights then I would match in an empty field on a clear day with the sun about 15 degrees high, put threads on an unshaded horizontal section of cloth that is at chin level and pick, that might not be the ideal compromise lighting condition but certainly better than being lit by only candles or blue sky (even overcast light is significantly bluer than direct sun). Labeling the threads to tell them apart then writing what they look like under lighting conditions you might be seen in before choosing would be better still, and probably worth it for a wedding dress or something. Or maybe you could find out who weaved the cloth and ask what kind of thread it's made of. And try to buy some but might be expensive. Even a giant megacorp would probably inconvenience themselves for 1 spool if someone called and offered enough money for the same thread as a sentimental heirloom. Also never use a male to match, our eyes aren't as good with colors as females. Up to half of women are tetrachromats, if you're tetrachromatic in the right place then a yellow laser and a matching mix of red and green paint would be different colors and everyone who said they matched would seem colorblind. Sagittarian Milky Way (talk) 22:50, 20 November 2021 (UTC)


 * I assume that in "match under low CRI light", the idea is that two coloured objects are compared under the same low-CRI light source. The answer depends on what you mean by "colours that are equal". If the colour of an object is identified with its reflectance spectrum, then objects of the same colour will match under any light source. If, however, the question is about colours appearing identical to the (human) eye, then it is very well possible that colours that in broad daylight look the same to some individual appear rather differently to that individual under sodium light (and conversely). It is also possible that colours that look the same to some individual in broad daylight appear at the same time rather differently to another individual. --Lambiam 12:01, 21 November 2021 (UTC)