Wikipedia:Reference desk/Archives/Science/2019 June 21

= June 21 =

People with influenza drinking coffee
Hello. If a person contracts influenza, is it considered safe or medically desirable for him or her to drink coffee? FreeKnowledgeCreator (talk) 03:05, 21 June 2019 (UTC)
 * We don't do medical advice.
 * As to coffee and influenza, then advice is split anyway. Hydration is important, thus drinking something; but coffee can have a diuretic effect, thus the opposite. Paracetamol has been standard advice for years, although recent studies (Respirology, 2015) found no effect – but then placebos are still one of the most effective treatments for flu generally, even better than homeopathy. Many proprietary formulations of paracetamol or ibuprofen will include caffeine anyway, which has a useful effect for the rapidity of their effects on acute headaches, but no relevance to flu.
 * So no-one knows. And if they did, we wouldn't tell you here anyway. Andy Dingley (talk) 11:11, 21 June 2019 (UTC)


 * The dose makes the poison.41.165.67.114 (talk) 11:47, 21 June 2019 (UTC)
 * I wasn't asking for medical advice. I didn't say I had influenza, and I didn't say I planned to drink any coffee. It was purely and simply a general question, motivated by curiosity. There is no need to be rude. FreeKnowledgeCreator (talk) 04:40, 23 June 2019 (UTC)
 * Perhaps you could expound on what inspired the question? Something in the news, maybe? ←Baseball Bugs What's up, Doc? carrots→ 16:25, 23 June 2019 (UTC)


 * The only reason I can think not to is that the flu can cause diarrhea, and coffee also can cause a bowel movement, so combining the two may be unwise from that POV. And I'm not sure how easy it is to keep coffee down on an upset stomach. SinisterLefty (talk) 18:07, 23 June 2019 (UTC)


 * Influenza can sometimes cause stomach upset, but "stomach flu" is a misnomer - that's caused by foodborne illness. Matt Deres (talk) 17:34, 24 June 2019 (UTC)


 * A small study seemed positive about the idea:  But WebMD recommends against it as caffeine diuresis might dehydrate:   People suggest various odd teas that might be desirable (no medical basis):   Capsules are sold in the UK that contain caffeine with paracetamol (that's acetaminophen/Tylenol) supposedly to increase the pain relief.   On the other hand this news article links them to stroke .  We cover medical science, and lack of science, here, but we don't tell you what to do - you'll have to make up your own mind on that. Wnt (talk) 21:24, 25 June 2019 (UTC)

Long-term complications from microfracture surgery?
I heard somewhere that for professional athletes, complications may develop approximately eight years after undergoing microfracture surgery. Is there any literature out there which supports this? 67.83.118.216 (talk) 05:38, 21 June 2019 (UTC)


 * This paper apparently on 1200 patients claimed worsening results in 5% of patients, but no control group and honestly this is a very weird paper, I wouldn't trust it. I get the sense this paper was written to promote the practice. [This much smaller paper https://journals.sagepub.com/doi/full/10.1177/0363546508316773] reported 6 out of 17 patients seen over 5 years saw their symptoms get worse after surgery. [This seems to be a quite comprehensive article https://journals.lww.com/jbjsjournal/Fulltext/2007/10000/A_Randomized_Trial_Comparing_Autologous.2.aspx] and compares to a group treated with autologous chondrocyte implantation. They found that the "failure" rate increases from 2 years to 5 years, going from about 5% to about 23% in both groups. Yet another paper also found a proportion of patients who did worse over up to 10 years of followup, though they get extremely technical and don't have just one value to report. They also mention in their discussion another randomized trial claiming that the chance of backsliding seems to be higher for microfacture treatment than for other treatments over a ten year followup. Concluding, though, I think in all of these cases it may be hard to tell unless you really dig into case reports whether the complication is caused by something actually going wrong as a result of the surgery, and something just deteriorating as it was going to regardless. Seems to be a forgone conclusion that as a population, people getting either treatment are better off on average than people who got nothing, but I didn't look back to find the articles that support that claim. The last paper I linked does describe how many patients required additional surgery, so maybe that helps give an idea of what you're looking for. Someguy1221 (talk) 06:01, 21 June 2019 (UTC)

Immune system and infectious diseases
Are the chances of a person contracting a serious infectious disease influenced by the strength of their immune system? So for example, if 2 people were exposed to the same virus or bacteria which causes a serious illness, would the chances of one of them developing symptoms and being affected by it be influenced by the strength of their immune system? I guess my question is why is it that not everyone is affected when exposed to the same bacteria, virus or other disease causing agent? 90.210.250.247 (talk) 21:51, 21 June 2019 (UTC)


 * Yes, the general strength of the immune system is important, but there's also specific immunity to specific organisms. For example, if you've previously been exposed to a disease, or had a vaccine, then your body may still have antibodies designed to target that organism, which gives your immune system a significant jump-start on fighting off a new infection. This immunity tends to fade with time, and some infectious diseases, like the flu, mutate every year, so immunity doesn't last. Also, there's genetic immunity. For example, those with one copy of the sickle-cell gene are immune to malaria. There are many other examples. SinisterLefty (talk) 23:32, 21 June 2019 (UTC)


 * Not actually immune to malaria; from the linked sickle-cell article: "humans with one of the two alleles of sickle cell disease show less severe symptoms when infected with malaria."--Wikimedes (talk) 21:54, 22 June 2019 (UTC)


 * Occasionally weakness of the immune system can help (CCR5). It all depends on the pathogen and the person involved. Wnt (talk) 21:28, 25 June 2019 (UTC)

Why do people have fingerprints?
One reason I can think of is that fingers are too slippery otherwise so grabbing objects would be more difficult, but that doesn't sound convincing. In fact, those kind of wrinkles are visible on the rest of the inside of hands as well. Maybe it's simply "cheaper" (evolutionary wise) to do have wrinkled fingertips where it would cost more to have a flat skin, but then I'd like to know what's so different about my nose, or the upper side of my hands that don't have this feature. Joepnl (talk) 23:18, 21 June 2019 (UTC)


 * Your first instinct was right, it's for improving grip. Our palms are also used to grip things, so they have such wrinkles, too. SinisterLefty (talk) 23:27, 21 June 2019 (UTC)


 * Also for (or as outcomes of) improving touch sensitivity through friction, maintaining the health of the Epidermis, and helping the Epidermis and Dermis to cohere. See Fingerprint and Dermis.
 * (This being a reference desk, let's all remember to give actual references, people :-). Sometimes we might learn/remember additional facts ourselves as well as better answering the querants. ) {The poster formerly known as 87.81.230.195} 2.122.177.55 (talk) 00:07, 22 June 2019 (UTC)


 * At least Fingerprint is completely wrong saying "These ridges may also assist in gripping rough surfaces and may improve surface contact in wet conditions" linking to an article that says the very opposite. "Scientists say they have disproved the theory that fingerprints improve grip by increasing friction between people's hands and the surface they are holding." ... "This confirmed that fingerprints do not improve our grip, because they actually reduce our skin's contact with the objects that we hold." Which is what I was thinking. Not convinced of health reasons either. Even without clothes, my upper legs happen to experience friction when walking, and they can do without wrinkles. Joepnl (talk) 00:41, 22 June 2019 (UTC)


 * That source sounds wrong, then. Car tires have treads to increase traction. This prevents hydroplaning, and something similar can also happen between smooth skin and a smooth surface, with a layer of liquid between them, like oil and/or water. And the area of contact does not have a direct effect on friction. The formula for frictional force specifies that it is only a function of the coefficient of friction and the normal force. And that coefficient of friction is reduced if a layer of liquid is between the two objects, which is why it's important to provide ridges that extend above the troughs containing the liquid, whether on a tire or a finger.


 * As for your legs, I'm guessing they aren't very hairy, as hair seems to serve the purpose (among others) of reducing friction. This is why many land animals have hairless toe pads, on an otherwise hairy paw, to increase traction. SinisterLefty (talk) 00:46, 22 June 2019 (UTC)


 * Even if that's true, what would my great (^50) parent need to pick up that's slippery where it would help to develop special wrinkles to hold it? Joepnl (talk) 01:07, 22 June 2019 (UTC)


 * 50 generations ago (500 AD ?) there was all sorts of pottery and such which could be slippery when wet. But going back much further, how about a fish he grabbed out of a river, barehanded, and would like to eat ? SinisterLefty (talk) 01:13, 22 June 2019 (UTC)


 * Tyres do not generally get increased traction from treads - see Racing slick for example. The tread might allow the rubber to squirm and generate heat, and hotter rubber is generally stickier, but that's an eddect of heating not the tread.  The main purpose of treads is to deal with water on the road/track, or to provide traction on muddy or rough terrain, where the tread can bite into the terrain.--Phil Holmes (talk) 09:46, 22 June 2019 (UTC)


 * I would consider racing tracks to be a "special case" where treads are not needed because they only drive when the track is dry and relatively clean. In "the real world", treads are needed to increase traction via all the mechanisms you listed. So, that is the "general case". SinisterLefty (talk) 11:57, 22 June 2019 (UTC)


 * Slicks are also used in rallying and on road circuits like Monaco. Tread does not increase friction - it can add mechanical grip, which is not the same.  In some circumstances this can lead to better traction, but not in all.--Phil Holmes (talk) 16:09, 22 June 2019 (UTC)


 * Re: hair: where the friction takes place it's hairy like a baby. Joepnl (talk) 01:09, 22 June 2019 (UTC)


 * So hairless then ? SinisterLefty (talk) 01:13, 22 June 2019 (UTC)


 * Regarding the source, it does say fingerprints "...may allow water trapped between our finger pads and the surface to drain away and improve surface contact in wet conditions.". That I agree with. Note that the link was to a BBC report on the source, not to the source itself (like a technical paper). Unfortunately, reporters often get it wrong when reporting on science topics. SinisterLefty (talk) 01:13, 22 June 2019 (UTC)

Not surprisingly, other primates - gorillas, chimps, etc. - also have fingerprints, but the surprising one to me is that koalas have them too - https://www.abc.net.au/news/2018-07-01/biometrics-koalas-and-wood-glue-fascinating-fingerprint-facts/9920802?pfmredir=sm It's believed to serve the same purpose as in humans. Remember that when a koala grabs your smart phone. HiLo48 (talk) 00:20, 22 June 2019 (UTC)


 * A case of "sticky fingers" ? SinisterLefty (talk) 01:04, 22 June 2019 (UTC)


 * Some research says fingerprints are used to feel the surface roughness of objects (i.e. enhance the sense of touch). The idea would be that a flat finger would need a high density of nerves to feel the change of pressure over the finger surface, whereas a wrinkled finger running over a surface can feel the bumps and drops and deduce roughness information without needing fine resolution. Here's an article but it's really super-technical. Tigraan Click here to contact me 11:33, 25 June 2019 (UTC)