Wikipedia:Reference desk/Archives/Science/2018 January 12

= January 12 =

Bizarre error in official PLU code record?
If you look up PLU code 3474 on plucodes.com, you see that it's something called "Saffron" sweet potato. If you drill down and look at the whole record, you get this info which says that the botanical name is Escobedia linearis.

Now, I don't know what Escobedia linearis is, but it's in a family of parasitic plants that includes Indian paintbrush and Pedicularis densiflora... and very little that is edible. I would be shocked if E. linearis bears anything that resembles a sweet potato.

It seems much more likely that the species here should be the ordinary sweet potato, Ipomoea batatas. But what does E. linearis have to do with anything, and why is it in the official PLU code data? —Keenan Pepper 01:43, 12 January 2018 (UTC)


 * The phrase "sweet potato/yam/kumara is used, which seems a tip-off that the common name is not very cladistic in nature. I haven't tried to figure out what this plant is, but I would be prone to suspect it might actually bear something that vaguely resembles a yam or sweet potato, perhaps saffron-colored.  As with the common tomato, it is hard to guess whether a plant will bear wholesome fruit by looking at its relatives.  Caveat: the image I found doesn't look like much of a potato!  (from ) Wnt (talk) 02:24, 12 January 2018 (UTC)


 * So you think E. linearis could actually produce food, and this be known widely enough that it has a standard 4-digit code for use in grocery stores? We should have an article about it! —Keenan Pepper 02:41, 12 January 2018 (UTC)


 * I don't know, but these PLU codes are published in multiple places; I'd think someone would have noticed. this source says that "azafrancillo" ('saffron', according to Google Translate) variety of sweet potato is indeed this species. Wnt (talk) 02:59, 12 January 2018 (UTC)
 * That link to kumara that you provided is inappropriate as it links to an article about a South African plant. Kumara (different language entirely) is indeed the Maori word for sweet potato, and in New Zealand it is, to my knowledge, a unique variety of sweet potato. It and its shade of meaning is discussed in the main article you linked to, so there was no need for the South African link. Akld guy (talk) 05:30, 12 January 2018 (UTC)
 * I agree that the link doesn't relate to what kumara is but I find your clarification equally confusing. Kumara is generally used for any sweet potato, or at least any of the 3 varieties common in NZ i.e. red (also sometimes called Owairaka or sometimes purple although there are also other recent imports often called purple), gold (also sometimes called Toka Toka or sometimes brown) and orange (also sometimes called Beauregard) . As far as I know, all 3 varieties are accepted to be derived from varieties introduced by European settlers or later, and don't share much in common with the varieties grown by Māori pre-contact  .  They may or may not be unique enough that they could still be called unique to New Zealand. My impression is that for at least one variety, the orange this isn't the case hence the alternative name Beauregard, see List of sweet potato cultivars. It may be what people in NZ sometimes think of when you mention sweet potato, if they don't just automatically translate it to kumara, given it looks similar to what I think is the most common "yam" or sweet potato in the US. (Although I'm not sure how many of those in the US are actually Beauregard even if it came from there. However from my experience, nowadays at least, everyone still just call it kumara or orange kumara or whatever. You sometimes hear sweet potato for very recent imports or those that haven't yet taken any real foothold here, although even then kumara is normally mentioned somewhere e.g. [//www.stuff.co.nz/life-style/homed/garden/93034036/king-of-kumara].  For further clarity the red variety is the traditional variety (i.e. it's what was probably considered kumara 50 years ago) and remains the most popular. But at least wherever I've been in Auckland, most fruit and vege shops, as well as supermarkets nearly always have all 3, and as said all called kumara. And if anything the gold is less common than orange nowadays. In fact [//www.stuff.co.nz/business/94765761/kumara-shelf-supply-weened-through-shortage-but-prices-at-peak] suggests orange could overtake red within 5 years (of 2017) due to changing demands.  There have been some attempts to reintroduce kumara grown pre-contact commercially, but these haven't been particularly successful as yet. As hinted at in the earlier sources and also others like   [//www.openpolytechnic.ac.nz/assets/Marketing/Research/Current-working-papers/MaoriKumara.pdf], even finding these pre-contact varieties has been difficult.  Now this is English usage, but I'm pretty sure te reo is the same, or probably even more extreme. (I'm not sure if these's any term for sweet potato which isn't kūmara.)  Nil Einne (talk) 09:09, 12 January 2018 (UTC)
 * has a better image. I do see some tubers. The source is Mexican and in Spanish, but machine translation of the description gives:
 * "This tuber is used as a coloring and flavoring in certain stews; It is scarce, it is only present in one of the municipalities studied, Tacotalpa. It should be mentioned that the information regarding this species is scarce and is commonly confused with turmeric. The cultivation is of easy vegetative propagation due to the existence of abundant buds in the rhizome."


 * So it seems like the tubers are mostly used for colour and flavour rather than as a food source, which may explain why it's called "azafrancillo" or "saffron". I'm not sure why sweet potato is used, but maybe it is because it's the most commonly consumed tuber by the people who use it so "sweet potato" is something similar to "tuber". (You could probably say there are similarities with the word "yam" in English, and even more so with "corn".)
 * Nil Einne (talk) 07:05, 12 January 2018 (UTC)
 * BTW, it's also worth noting that given the large number of varieties, local growing conditions etc, even for something which is Ipomoea batatas people's mental picture is likely to vary. When I was in Malaysia, during Christmas I bought some kumara. The flesh and skin looked like what you'd call orange kumara in NZ but these very tiny, IIRC smaller even than what I'd call small potato. I don't know if I've ever seen a kumara in NZ that small. I think these were very small even by Malaysian standards as e.g. [//www.shutterstock.com/video/clip-11754380-stock-footage-tawau-sabah-malaysia-circa-september-unidentified-woman-selecting-sweet-potatoes-at-sunday.html] those don't look very small although that's in Sabah no KL or peninsular Malaysia. And these in KL although apparently from a prepared food or drink store rather than a market or supermarket also don't look that small. But even so, the point remains what rural villagers in Tacotalpa think of as a sweet potato may not be that similar to what you and I do even ignoring whatever colloquial usage and language translations issues that arise. Nil Einne (talk) 09:26, 12 January 2018 (UTC)

PID controller
PID controller uses the standard conventions for the gains, which is well and good:


 * $$K_\text{p}$$ is the proportional gain, a tuning parameter,
 * $$K_\text{i}$$ is the integral gain, a tuning parameter,
 * $$K_\text{d}$$ is the derivative gain, a tuning parameter,

But I'm dealing with a case where the PID controller uses this weird non-conventional notation:


 * $$K_\text{P}$$ is "Velocity gain" (note capital P)
 * $$K_\text{i}$$ is "Velocity gain"
 * $$K_\text{p}$$ is "Distance gain" (note lowercase P)

Since "$$K_\text{i}$$" looks identical to "$$K_\text{i}$$", and has the right units (milliseconds), I'm assuming they map to each other. But what about $$K_\text{P}$$ and $$K_\text{p}$$? Which one map to the proportional gain and which one map to the derivative gain?

The acceptable range (according to the controller) of $$K_\text{P}$$ is 0 to 10, unit-less. And 1 to 5000 for $$K_\text{P}$$, also unit-less. Mũeller (talk) 02:25, 12 January 2018 (UTC)
 * The quoted weird notation strongly suggests a mistake. The name proportional–integral–derivative controller must imply it has three different gain constants which correspond in reality or metaphor to velocity-distance-(de)acceleration respectively. Have you a reference such as a product specification or data sheet that shows this case? SdrawkcaB99 (talk) 10:16, 12 January 2018 (UTC)

Brown crap on people's teeth that doesn't go away
Sometimes I've seen people with brown who-knows-what on their teeth which stays there day after day. What's that all about? Is it permanent? How did it get there? I'm not talking about a diffuse staining from coffee or nicotine; but it looks like they've eaten recently and got some crap stuck to their otherwise normal teeth. I've seen this several times on different people I've known but I can only dream of the kind of social skill it would take to broach that subject without causing offence. 129.215.47.59 (talk) 17:46, 12 January 2018 (UTC)


 * Sounds like dental tartar. DuncanHill (talk) 17:48, 12 January 2018 (UTC)
 * Could also be dental fluorosis, standard tooth decay or celiac disease. Justin15w (talk) 21:28, 12 January 2018 (UTC)
 * I have brown spots on a couple of my own teeth where the enamel has chipped off, but there is no actual decay. At some point I'll get these covered up, but fortunately they do not show even when I smile. Someguy1221 (talk) 22:55, 12 January 2018 (UTC)

Bollockwarts
Is it true that orchids were once called bollockwarts as they can resemble testicles? The orchid page does not mention this.149.254.235.44 (talk) 22:32, 12 January 2018 (UTC)


 * Orchids are still called testicles, you just don't know it. The word is derived from the Ancient Greek ὄρχις (órkhis), which literally means 'testicle'. Though Google would suggest that no one calls them bollockwarts, now or in the past. Someguy1221 (talk) 22:50, 12 January 2018 (UTC)

Ah no. I its bollockworts. Can I have that as a user name?149.254.235.44 (talk) 23:52, 12 January 2018 (UTC)
 * Is "bollock(s)" considered a serious vulgarism in British English? If so, then probably not. ←Baseball Bugs What's up, Doc? carrots→ 00:47, 13 January 2018 (UTC)


 * Not really. I wouldn't expect to hear it in polite company, but compared with cunt it doesn't really have anything like the same impact. In fact describing something rubbish as "a load of old bollocks" is practically acceptable in many environments short of the vicar's tea party. There again I work with mechanics and engineers, swearing is a fact of life. Greglocock (talk) 02:59, 13 January 2018 (UTC)


 * Aside from a few comments on internet fora, I cannot find a good source to say that this word was ever used in that manner. One person claims it was once listed in OED, but the 1928 version that's available online doesn't list it. Anyway, it's not the job of Wikipedia to list every word ever used to describe a thing, though if the rumor could be verified, that would be something for Wiktionary. Someguy1221 (talk) 03:05, 13 January 2018 (UTC)


 * The word bollockwort does appear in the OED Third Edition (Revision of June 2008) as an obsolete word for a kind of orchid, but the two cites are from around 1300 and 1500 (the latter being from "Anglo-Saxon and Old English Vocabulary"). "Bollock grass" is another term for a type of orchid and has more recent usage.  The word "bollock" was, according to the OED, "Apparently in standard use until the 17th cent., after which the word is regarded as coarse slang."   Dbfirs  08:31, 13 January 2018 (UTC)


 * There appears to be a German equivalent Hodenkraut. Cheers ✦  hugarheimur 08:51, 13 January 2018 (UTC)


 * See also our article Bollock dagger for another example of the term being used without contemporary offensiveness. Contrary to some people's hopes, it refers to form rather than function. {The poster formerly known as 87.81.230.195} 90.200.41.3 (talk) 18:48, 13 January 2018 (UTC)


 * Our Bollocks article includes some research conducted by the BBC into the 'relative severity of the various profanities, as perceived by the British public'. The results, published in 2000, reported that "bollocks" came in at 'eighth position in terms of its perceived severity, between "prick" (seventh place) and "arsehole" (ninth place)'. So there you have it. Alansplodge (talk) 00:02, 14 January 2018 (UTC)


 * It's too much of a coincidence that the word bollockwort was mentioned on the BBC2 TV programme "QI XL" 24 hours after the question was asked here, so I wonder if our questioner has some connection with the programme?  Db<i style="color: #4fc;">f</i><i style="color: #6f6;">i</i><i style="color: #4e4;">r</i><i style="color: #4a4">s</i>  07:53, 14 January 2018 (UTC)

When I see a discussion about this word, it's hard to resist posting a definition I came across in an old dictionary at the math library at UCLA: "*bollock* _Naut._   Either of two blocks attached to the topsail-yard in a ship, for the topsail-ties to reeve through"

--Trovatore (talk) 08:28, 14 January 2018 (UTC)


 * The same sense of bollocks is recorded in C W T Layton's 1955 Dictionary of Nautical Words: "Blocks in bunt of topsail yards of large ships. Topsail ties are rove through them to increase lifting power"; and in A Ansted's 1898 Dictionary of Sea Terms: "blocks secured to the middle of the topsail yards in large ships; the topsail ties pass through them, and thereby gain an increase of power in lifting the yards."   <i style="color: blue;">D</i><i style="color: #0cf;">b</i><i style="color: #4fc;">f</i><i style="color: #6f6;">i</i><i style="color: #4e4;">r</i><i style="color: #4a4">s</i>  12:15, 14 January 2018 (UTC)
 * Looking at a few images of topsail yards suggests that the nautical term may well derive from sailors noting a similarity to the relevant male organs! Wymspen (talk) 16:14, 14 January 2018 (UTC)

In 1977 the Sex Pistols relased an album entitled Never Mind the Bollocks, Here's the Sex Pistols. If you read the article you will find that a record shop manager who displayed posters for the album was prosecuted for displaying an indecent advertisement. During the case evidence was presented that bollocks was an Old English word for a priest and, in the context used on the album cover, meant "nonsense". The judge reluctantly ruled that the shop manager was not guilty saying "Much as my colleagues and I wholeheartedly deplore the vulgar exploitation of the worst instincts of human nature for the purchases of commercial profits by both you and your company, we must reluctantly find you not guilty of each of the four charges." So if you disagree with your priest tell him he's talking bollocks. Richerman (talk) 16:57, 14 January 2018 (UTC)


 * When I saw the lawyer's argument that "bollocks" is an old term for a priest I immediately thought that this was something he had made up to get his client off the hook.  However, the dictionary says that the normal meaning of "bullock" is "castrated bull".   Is there some connection given that the priests of the Roman Catholic church (the parish priests of the time) do not have normal sexual relations?   Alternatively, is there some connection with the most solemn pronouncements of this church (which the priests circulated to their parishioners) which are known as "bulls"?   With the arrival of the Reformation these were treated as nonsense, Latimer commenting in a 1537 sermon "I send you here a bullock which I did find amongst my bulls." 195.147.104.148 (talk) 21:33, 16 January 2018 (UTC)