Wikipedia:Reference desk/Archives/Science/2018 April 25

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April 25

Matching a light source to a solar panel

I'm hoping someone can help me. I'm trying to make up a simple set-up to recharge a lot of solar powered decorative strings of lights. They each have a solar panel about 60 mm by 60 mm charging two AAA batteries. I'd thought that just putting them all under a light bulb would work, but now I realize that I might have to use a special kind of bulb that puts out the same light spectrum that the solar panels use. I can't find out much about what type of light these panels work best in. I'd appreciate any links or information anyone can give me. Thanks in advance 49.197.192.93 (talk) 03:26, 25 April 2018 (UTC)

From a little searching, it looks like anything that puts out visible light should work well enough. Sure, you might be able to increase efficiency a bit with very finely tuned light sources, but it sounds like that wouldn't be worth the time or money given what you're doing. Sure it's not better to just remove the batteries and charge them with a charger? You can find battery chargers that take lots of batteries at once. Or are the batteries not removable? Another suggestion is that, if this is something you do often, it might be worth it to wire charging plugs into the strings. Since they're battery-powered, this is low-voltage wiring: just add in DC plugs and get a suitable power supply to plug them into. --47.146.63.87 (talk) 04:24, 25 April 2018 (UTC)

(OP) Thanks for those thoughts. Taking the batteries out involves undoing 4 tiny screws, and we usually have 9 different strings on display in a market stall then need them recharged for next day. I hadn't thought of putting a charging plug into each one, that might well be the answer. I'll wire an ammeter into one of them and do some tests under an ordinary light bulb first.49.197.115.7 (talk) 06:44, 25 April 2018 (UTC)

An alternative would be to forget the batteries and solar chargers, and just wire the lights to a low voltage DC supply (probably 3v if the units use two 1.5v batteries). I've done this successfully with some of my solar lights. One good DC supply should run them all because the current will be small. It doesn't have to be smoothed, so a cheap mains transformer with a single diode on the output might suffice, though full-wave rectification might be better. Dbfirs 07:07, 25 April 2018 (UTC)

(OP) I've just hooked an ammeter into the battery circuit, and the lights use about 30mA when running. Late afternoon sun square on to the panel puts in 35mA, and putting the panel up very close to a selection of light bulbs gives 10mA at most. (So close that the solar panel gets quite hot very quickly). I need to display them pretty well exactly as a customer might buy them, so the charging socket idea seems the best one yet. 49.197.119.149 (talk) 06:45, 26 April 2018 (UTC)

What animals eat feces as a normal behavior?

I've read the following paragraph on educalingo site: "Coprophagia /kɒp.rə.ˈfeɪ.dʒi.ə/ or coprophagy is the consumption of feces. The word is derived from the Greek κόπρος copros, "feces" and φαγεῖν phagein, "to eat". Many animal species eat feces as a normal behavior; other species may not normally consume feces but do so under unusual conditions. Coprophagy refers to many kinds of feces eating including eating feces of other species, of other individuals, or its own, those once deposited or taken directly from the anus.". I'd like to know what animals most familiar with this phenomenon. I've heard about pigs something like that but I'm not sure. 93.126.116.89 (talk) 04:07, 25 April 2018 (UTC)

Have you read our Coprophagia article? Note that you're posting on Wikipedia, not Educalingo. That article gives many examples of animals that do so. What do you feel is not adequately discussed in that article? --47.146.63.87 (talk) 04:12, 25 April 2018 (UTC)

What is a "det. officer?"

(Moved to the Humanities Desk as per the original poster's intent. It's been answered, but it might as well be archived in the right place. --69.159.62.113 (talk) 00:31, 26 April 2018 (UTC))

Does Beano raise the effective glycemic index of beans?

I assume most people know that Beano is a product intended to allow you to eat beans (and some other foods) without experiencing certain inconveniences, or at least reducing them. According to our article, it works by breaking down oligosaccharides into simple sugars.

So does this raise the effective glycemic index of those foods, and if so how much? Is it a situation of "you thought you were being virtuous by eating beans, but to your pancreas, they look like ice cream"? --Trovatore (talk) 20:51, 25 April 2018 (UTC)

As you no doubt suspect, it will increase the digestibility of certain foods. This will possibly raise the glycemic index by losing fewer carbohydrate molecules to farts. Abductive (reasoning) 06:19, 26 April 2018 (UTC)

Thanks for responding, but I was hoping for something more substantive than "possibly", which I could figure out for myself. Any actual data or studies? --Trovatore (talk) 07:14, 26 April 2018 (UTC)

I once read a study of the calories lost to flatus (generally), but have been unable to find it again. Google is probably accidentally censoring it. Sorry. Abductive (reasoning) 23:19, 26 April 2018 (UTC)

I doubt "calories lost" is the key issue here. The point is that the oligosaccharides would be taken up more slowly than the simple sugars the enzyme breaks them down into. So the prompt response in blood sugar (and insulin) might be greater if you have the Beano, even if total calories eventually absorbed are about the same. That's the effect I was trying to find out about. --Trovatore (talk) 23:46, 26 April 2018 (UTC)

You are one of the top ten experts in this field, if one measures by characters typed. Abductive (reasoning) 03:44, 27 April 2018 (UTC)

????? I see plenty of discussions/speculation on this and related issue elsewhere [1] [2] [3] [4] [5]. Beano themselves while not really dealing with the glycemic index issue mention "As a result, it has been estimated that the use of beano® will produce an additional two to six grams of carbohydrates for every 100 grams of food treated by beano®." There is also the paper I highlighted below. I see zero reason to think the minor comments here somehow make them "one of the top ten experts in this field, if one measures by characters typed." Nil Einne (talk) 10:04, 27 April 2018 (UTC)

One assumes that people have already searched for sources before posting their question. And reading those sources only confirms my suspicion that this discussion is as advanced as any held anywhere in the world, ever. Abductive (reasoning) 21:01, 28 April 2018 (UTC)

Your reply makes absolutely zero sense. Of course a good OP would have searched before asking. They also failed to find something that's why they're asking. And your comment makes zero sense. I did not claim these are even close to the best discussion held. There is zero reason to think they are. For starters, they completely missed the first RS I found below. Second, discussions held in forums are rarely great sources. When searching for answers, I frequently comes across crappy discussion threads. Sometime they are similar to those here. Rarely they are better than those here. How I often also find decent RS which have been completely missed by many of the discussions. The presence of a bunch of not very good discussions is no reason to think that they are the best. (And IIRC some of those sources considered stuff not yet mentioned in this thread anyway.) I guess you're new to the internet, but that's simply not how the internet works. A lot of the internet is full of terrible quality discussions. Sorting the wheat from the chaff is one of the key reasons why the RD exists. Another reason is to provide quality sources, often reliable sources which internet discussions aren't. Reliable sources were specifically requested in this thread, so I did not spend a great time trying to find quality discussions other than to look for RS. I didn't spend a great time looking for RS either since I'm only mildly interested in this. This is clearly something that people have considered before, enough so that someone actually did a placebo controlled examination of the effect of beano on postprandial glucose concentration. There is no reason to think anyone in this thread, is anything close to an expert or has considered this at anything close to the level considered before. I mean I'm guessing no one in this thread knew of the source below until I found it either and while it doesn't directly deal with glycemic index, it's fairly related. Nil Einne (talk) 22:36, 28 April 2018 (UTC)

I remember now that the beano FAQ response is one thing that was mentioned in one of the discussions. While true it's only of limited relevance to the question, I wouldn't say it's completely irrelevant and I also wouldn't be surprised if no one here knew of if until I brought it up. Many of the discussions I linked to are both highly flawed (I think one of them possibly even conflated alpha-galactosidase that beano provides and alpha-glucosidase that acarbose inhibits), and yet contain limited new info, as is common with such things including in cases where we can be sure there have almost definitely been informed discussions somewhere. To be clear, I'm not trying to blow my trumpet here. My sole point is that with my tiny about of research, I've uncovered stuff that probably wasn't know to anyone in particular the OP. It also fairly likely that someone who is an actual expert in related areas is likely to be able to come up with a far more informed discussion. (With no disrespect intended to the OP, their background makes me thing they are quite far from an expert in areas for which experts obviously do exist and who would likely to be able to understand this issue far better without having specifically studied it.) Especially if multiple experts in different areas collaborate. Whether this has happened I have no idea, but I also know it can't be ruled it. (By collaborate here I'm mostly not thinking of some sort of scientific collaboration. It could be some people worked together to write answer a question in some newspaper column. It could be it came up over dinner for some reason and they talked about it.) Ultimate point being the idea the OP was an expert in this particular issue, or this discussion was somehow highly informed on the issue compared to discussions that may have taken place all over the world (some of which could be documented no where) is unsupported, and very unlikely Nil Einne (talk) 23:20, 28 April 2018 (UTC)

I completely agree. I am no sort of expert on this question. However, if you don't mind, I am in fact a singular individual, and therefore prefer not to be referred to in the plural. --Trovatore (talk) 05:57, 1 May 2018 (UTC)

But wouldn't someone who has so much gas complaints that he/she wants to use this have slower absorption of these sugars to begin with compared to normal people? Count Iblis (talk) 02:14, 27 April 2018 (UTC)

I came across this small placebo controlled study [6]. It didn't deal with the glycemic index but did look at the effect on postprandial glucose concentration (as well as appetite). The interaction between beano and acarbose may also be of minor interest [7]. Nil Einne (talk) 10:04, 27 April 2018 (UTC)

My indenting was totally fucked up by another editor here [8]. I've fixed it. Hopefully no one was confused in the mean time. Nil Einne (talk) 22:36, 28 April 2018 (UTC)

BTW, although you can get this even from the abstract or heck even the title ('Not Their Glycemic Response'), for the benefit of the RD I might mention the study found beano (called α-Galactosidase but the details mention they used some form of beano) had no statistically significant effect on postprandial glucose concentration for any of the meals tested, suggesting it possibly does not effect glycemic index. Of course far from proving it, especially given the tiny sample size of 12 people. (Admittedly this isn't the kind of thing you're likely to get the kind of funding to do a decent sample size test.) And this also contradicts the findings of the acarbose study. However we don't know the reason for that result. E.g. was it some sort of interaction between the activities of the two? Could it be it's something that only occurs in diabetics? Nil Einne (talk) 23:20, 28 April 2018 (UTC)

Realised I forgot to mention probably the most significant reason namely it was simply a statistical fluke. Nil Einne (talk) 15:14, 29 April 2018 (UTC)

Thanks, Nil, for an interesting link. --Trovatore (talk) 01:01, 1 May 2018 (UTC)

Statics: Which zero-force member can be removed without reducing structural strength?

I find it difficult to figure out this kind of problems. Can you name some simple rules? 161.185.160.21 (talk) 21:20, 25 April 2018 (UTC)

Our article is at Zero force member. Perhaps all of them can be removed. However if the loading is changed they would not be a zero force member any more. Graeme Bartlett (talk) 21:58, 25 April 2018 (UTC)