Wikipedia:Reference desk/Archives/Science/2023 April 20
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April 20 edit
"stay open ink" edit
"stay open ink" is used in printing and tattooing. search: "stay open ink" definition I can't find a definition. .... 0mtwb9gd5wx (talk) 12:04, 20 April 2023 (UTC)
- This seems to say that stay open inks are designed to remain fluid even if the container is left open indefinitely. --Jayron32 12:39, 20 April 2023 (UTC)
The physical explanation about mass influence on the severity while falling down? edit
What's the physical explanation on the fact that mass influencs on the injury severity while falling down? I remember that I saw in a physics book in past, that the more one presses on area, the more this area presses him back. Does it have something to do with the explanation on what I am looking for? ThePupil (talk) 19:20, 20 April 2023 (UTC)
- The kinetic energy of a moving object (at speeds where relativistic effects are negligible) is 1/2 * m * v**2, i.e. it is proportional to the mass. So double the mass means double the energy. When a moving object hits a immovable object that cannot be deformed (which an object falling onto concrete floor approximates) then the entire kinetic energy will go into deforming (and depending on its elasticity bouncing back) the object. So the more mass the object has the more energy goes into the deformation. You'll find a lot of detailed explanations if you search for "physics of car crashes" or "impact force". Here are some: [1][2][3][4] -- Random person no 362478479 (talk) 00:16, 21 April 2023 (UTC)
- The principle you mention is Newton's third law of motion and it indeed plays a role here. See Newton's laws of motion and Reaction (physics). -- Random person no 362478479 (talk) 00:33, 21 April 2023 (UTC)
- Also size and particularly height tends to go up with mass! So for an adult falling down compared to a child the arm is not only stopping a greater mass - but also one that has fallen from a greater height. NadVolum (talk) 08:28, 21 April 2023 (UTC)
- Not sure what it says about me, but my mind went directly to a different kind of falling. I had to read your answer several times until I realised why height played a role in it. :) -- Random person no 362478479 (talk) 08:35, 21 April 2023 (UTC)
Diamond mining and carbon release edit
With all the digging, blasting, transporting, grinding, shaking,etc. how much carbon dioxide is released to recover the average carat of diamond? 24.72.82.173 (talk) 21:37, 20 April 2023 (UTC)
- 143 pounds of carbon dioxide emissions per carat mined for the Ekati Diamond Mine, which the author of that article admits is a quick calculation, and likely on the low end of the spectrum across all diamond mines. --Jayron32 12:23, 21 April 2023 (UTC)
Evolutionary arms race of human pathogens edit
As I understand on the example of antibiotic resistance, in theory most or all human natural barriers (nasal mucus, earwax, saliva, etc.) against common bacterial and viral pathogens would have been rendered useless in just several decades due to high rate of mutations of such pathogens (which seemingly surpasses the adaptation rate of humans). But fortunately this doesn't seem to happen. Why is that? Does low evolutionary pressure come into play for some reason? 212.180.235.46 (talk) 22:21, 20 April 2023 (UTC)
- See Immune system. It is immensely complicated. People have different markers on their cells so everyone looks a bit different to germs - that's why there's all these allergic reactions and things listed on medicines otherwise we'd all look the same and the medical companies could cope easier. Then there's multiple layers of defences and at the end of it all the body also generates a huge random load of markers to recognize chemicals. They are pruned down to ignore the self and the rest are used to mark pathogens for killing and those are multiplied when a particular marker is seen, it is all terribly complicated. Basically defence in depth and randomness is used. Neither of those is available yet in medicine though for instance HIV was countered by having enough different medicines at once to conquer its mutational ability. NadVolum (talk) 07:57, 21 April 2023 (UTC)
- That article also describes the immune system of bacteria, yep even those single celled systems have quite a sophisticated immune system. And part of it involves being able to integrate bits of DNA from other cells so their descendants recognize an enemy - and unfortunately part of the same system enables pathogens to integrate defences from our medicines that other pathogens have evolved. NadVolum (talk) 08:18, 21 April 2023 (UTC)
- On their skin and similar external boundaries, living things have no problem using terrible, broad spectrum poisons, attacking the very fabric of any cells (theirs included, very often), such as lysozyme. While any [[skin flora[smaller living thing on the skin]] is engaged in some kind of battle royal against each and every kind of bacteria, viruses, and mold, plus lots of much bigger but still small mites and such; all competing for food, trying to eat and not be eaten. Under the sun (kind of atomic bombing for those creatures), rain and the occasional shower with soap (let's flood the battle field, baby! With napalm...), and many kind of random duress. Mother Nature is a bitch.
- Antibiotics are just a very small part of the battle, just a very rare if devastating event, not the ultimate weapon that you have to adapt to, or die. Antibiotic resistance come at a cost, and the cost means loosing against other foes taking their chance, or just don't caring about antibiotics (mold for instance).
- 2A01:E0A:1DC:4570:100A:386E:BD5B:D631 (talk) 13:33, 27 April 2023 (UTC)