Wikipedia:Reference desk/Archives/Science/2019 September 18

= September 18 =

Africa
On the Humanities desk there is a question entitled Africa which asked for further information concerning a Youtube link. I have tried to help with this and have seen the video mentioned but fail to under stand why the link can't be posted. I suspect this is due to the link being to youtu.be rather than youtube.com, yet the link is valid. I suspect the original post would have gained further assistance if the link could be provided in its original format. Why does Wikipedia reject this and how can this be overcome? Thanks Anton 81.131.40.58 (talk) 10:09, 18 September 2019 (UTC)
 * This has been discussed in April.
 * For a summary: youtu.be links are blocked by the global blacklist. The reason behind it is that redirect sites are not allowed, because (1) unless we start crawling all refs to know where the link ends you could get around the spam blacklist by bit.ly or similar, and (2) redirects could be modified after said crawling to point to a different page (ruining the source) or a malicious page. If you think that argument is nuts for youtu.be because the redirects are not going to change and are not going to go to anything else than Youtube, well, I agree. But that's how it is. Tigraan Click here to contact me 10:29, 18 September 2019 (UTC)
 * Why do you all have youtu and be separated by a period? That's not the website's name. ←Baseball Bugs What's up, Doc? carrots→ 11:18, 18 September 2019 (UTC)

Bugs, read the question again, S.T.O.P, Stop, Think, Orientate, Plan; and you may have the answer to your secondary question. Anton 81.131.40.58 (talk) 14:00, 18 September 2019 (UTC)
 * I saw it. I just don't understand what youtu.be is supposed to be. ←Baseball Bugs What's up, Doc? carrots→ 16:07, 18 September 2019 (UTC)
 * Probably the article on YouTube should explain youtu.be. --76.69.116.4 (talk) 17:23, 18 September 2019 (UTC)
 * Maybe it should, but I don't see "youtu.be" anywhere on that page. ←Baseball Bugs What's up, Doc? carrots→ 17:58, 18 September 2019 (UTC)
 * It is a common redirect for youtube.com, and save a few characters when you want to show a video, which is useful on social media. Not sure the info has enough encyclopedic value to be in the article. whois will tell you the name is under control of markmonitor.com, a company obviously acting on this matter on behalf of youtube / the-Gevil-company-not-to-be-named. Gem fr (talk) 22:24, 18 September 2019 (UTC)
 * Oh, is it only a redirect? I assumed it provided a different way to refer to the videos or something. --76.69.116.4 (talk) 05:59, 19 September 2019 (UTC)
 * It does. Looks to me (I may be wrong) youtu.be/something would be like youtube.com/watch?something Gem fr (talk) 11:12, 19 September 2019 (UTC)
 * The answer to BB's question is in the first line of Tigraan's 'summary'. —Tamfang (talk) 23:33, 20 September 2019 (UTC)
 * Why would anyone bother with youtu.be links when youtube links work just fine? ←Baseball Bugs What's up, Doc? carrots→ 11:55, 22 September 2019 (UTC)
 * Quite often people are just copy/pasting some stuff, if they came across a youtu.be link, that is what they will use. Now, why would people produce youtu.be link in the first place? Well, it save a few char and directly autoplay the video, and usually makes no other difference, so, why not?Gem fr (talk) 12:09, 22 September 2019 (UTC)
 * Copy and pasting yes, but I doubt it's 'just come across' very often especially for people asking questions here. The youtu.be is the link which Youtube itself will give if you use the 'share' function, whether on the desktop site, the mobile site or the mobile app. With the mobile app in particular, it's difficult to get a normal link AFAIK, other than by modifying the link they provide or by opening it in a browser than copying the link. Likewise if you want to specify a time and don't know how to do it manually, you may use the share link function. But to get a workable link you'll either need to copy and modify the time part (meaning you need to understand how query strings work, at least enough to know to replace the ? with a &) or you need to open the link in your browser then copy the URL. Well I'm sure there are tools you can find to automatically convert a shortened youtube URL to a full one too. Nil Einne (talk) 21:46, 25 September 2019 (UTC)

Subtended angle
Hello, I asked this question on the relevant article but I may get a better response here while advertising the article as underdeveloped :-

Is a subtended angle, the angle opposite the curved edge, in a triangle with two straight edges and one curved edge...? Or is there more to say or is that just incorrect? ~ R.T.G 11:27, 18 September 2019 (UTC)
 * An angle has two rays, and where some other segment or arc's endpoints touch each ray, the angle is subtended. Triangles don't have any curved sides. But a subtended angle can look like it. Maybe the diagram is a little confusing, because it shows two angles. The two angles have nothing to do with each other except that they are each subtended by the same arc. If you want a better answer, you could post your question on the Math ref desk. ←Baseball Bugs What's up, Doc? carrots→ 11:37, 18 September 2019 (UTC)
 * The curve is something of a red herring and not the easiest example. Take a look at the definition of a parsec, which is the distance at which an astronomical unit (or a line of that length) subtends an angle of one second of arc. Mikenorton (talk) 16:43, 18 September 2019 (UTC)


 * I think I sort of have it but I still want to spell it out and be sure if I can so will do to ask the math desk, thanks o/ ~ R.T.G 07:35, 19 September 2019 (UTC)
 * I have attempted an answer there. {The poster formerly known as 87.81.230.195} 90.202.210.107 (talk) 12:26, 19 September 2019 (UTC)

Anaphylaxis definition
Is any systemic allergic reaction considered to be anaphylaxis or is it only if it involves the respiratory or circulatory system? Are there also any changes to an ECG during anaphylaxis? Clover345 (talk) 17:15, 18 September 2019 (UTC)
 * Wikipedia has an article titled Anaphylaxis which is quite detailed. Under the "signs and symptoms" section, it does not appear that ECG data is used to diagnose anaphylaxis.  If you have any other questions about what that article says, please let us know.  -- Jayron 32 17:33, 18 September 2019 (UTC)

Role of Coenzyme Q-10
I read somewhere long time ago that Coenzyme Q-10 taken orally helps to stimulate growth of brain stem cells. Is there any literature to support it? Thanks, - AboutFace 22 (talk) 23:27, 18 September 2019 (UTC)


 * Generally speaking your brain can handle itself just fine without you messing with its homeostatic properties. There is research into the use of CoQ10 and other antioxidants as a secondary treatment for traumatic brain injury and neurodegenerative disorders, as it is known that oxidative damage plays a role in the failure of the brain to heal. This has been researched for a long time, but most of the studies on it are crap written by alt-med practitioners. There are many promising animal studies, although that scenario allows researchers to inflict the brain injury themselves in a consistent manner. Human trials yield inconsistent results. See also if you have access. Someguy1221 (talk) 00:17, 19 September 2019 (UTC)


 * Courtesy link: Coenzyme Q 10   2606:A000:1126:28D:31F8:40DA:20B3:80F8 (talk) 06:17, 19 September 2019 (UTC)
 * Remember drugs taken orally not only must survive the digestive track to get into the blood stream, but also must pass the blood–brain barrier. Also, +1 @Someguy1221. Any drug has secondary effects, and you may discover that stimulating stem cells (provided the drug actually do that...) comes at a price, actually impairing brain function, stimulating diseases (brain disease include, but any other body part, too), or whatever. Gem fr (talk) 11:03, 19 September 2019 (UTC)


 * Regarding passing the blood-brain barrier, I fear that direct brain injections may be somewhat less popular than pills. :-) SinisterLefty (talk) 13:48, 19 September 2019 (UTC)


 * It helps to stimulate the growth of the supplement industry. Count Iblis (talk) 15:23, 19 September 2019 (UTC)
 * true that, but it will also hinder the growth of all other industries Gem fr (talk) 18:24, 19 September 2019 (UTC)


 * How ? SinisterLefty (talk) 18:31, 19 September 2019 (UTC)
 * Should be obvious. People buying supplements are not buying something else, thereby hindering the growth of the other industries Gem fr (talk) 18:39, 19 September 2019 (UTC)


 * Not really, it's not like a purchase that size is likely to so deplete their money as to make it impossible to buy other things. And the trip to the store (or that area of the store) to buy the Co-Q10 might also inspire them to buy other items they see there. SinisterLefty (talk) 18:46, 19 September 2019 (UTC)
 * the size of the purchase is just irrelevant: the hurt industries may just the candy, cheap gadget, or whatever similar size industry. People have limited ressource to spend, if they buy supplement they will not be able to buy, say, candy, thereby hindering the candy industry. Unless you claim that buying supplement will give them more ressources, more than buying candy would? Gem fr (talk) 19:24, 19 September 2019 (UTC)


 * Your logic works if you only consider what that person buys, and if you assume they are at 100% of their spending capacity. Most people can just spend a bit more, either by reducing their savings by that amount or by going slightly more into debt. And we must also consider that the people making the item, delivering it, selling it, etc., also may make more money, so may buy more, as will the people they buy items from, etc. SinisterLefty (talk) 19:31, 19 September 2019 (UTC)
 * boring. You want to Keep believing in economical fairy tales, like, buying supplement will increase in one way or another buyers spending capacity, more than buying candy would? do it. I am done. Gem fr (talk) 19:55, 19 September 2019 (UTC)
 * Certainly, in an economy at a state of full employment, there is a finite amount of labor available. The existence of a dishonest industry directly implies there are people who want to work, are capable of working, and could be doing something useful, but are not. Someguy1221 (talk) 03:04, 20 September 2019 (UTC)
 * This is only true if the good and Co Q10 have a positive cross elasticity of demand. --47.146.63.87 (talk) 02:17, 20 September 2019 (UTC)
 * Cross elasticity is relevant good versus good, not good versus the whole economy. Buying a good that actually increase the productive power of the buyer (like say, a tool) could very well stimulate the growth of the tool industry AND the whole economy, but supplement won't do that, do they? My implicit assumption is that supplements do not actually qualify as "good" but rather as "neutral" (while drugs would be "bad"). That is, it does not change the whole productive power of buyers anymore than, say, candies. So a few things else will go down as much as supplement goes up. Gem fr (talk) 08:25, 20 September 2019 (UTC)


 * Lots of generalizations there. Drugs can increase or decrease productivity, depending on the drug and how they are used. For example, a painkiller that allows a person in pain to work is helpful, but if taken too much, dependency can result. And supplements are sometimes useful, if they solve a deficiency in some vitamin or mineral. SinisterLefty (talk) 13:15, 20 September 2019 (UTC)