Wikipedia:Reference desk/Archives/Science/2020 June 4

= June 4 =

Space X spacesuits
Why do the Space X dragon crew need a spacesuit during launch and docking but not for the phase in between? I assume it’s to do with cabin pressurisation. Clover345 (talk) 16:53, 4 June 2020 (UTC)
 * It isn't the same spacesuit they would wear during extravehicular activity; it's a special suit designed only for launch and re-entry portions of the flight. I can't find a Wikipedia article on the current suits, but the previous suits, known as "pumpkin suits" for their orange color, were known as the Advanced Crew Escape Suit (1990s and 2000s) and the Launch Entry Suit (1980s-1990s).  The Russian version is known as the Sokol space suit.  These are designed to protect the crew in case of accidental de-pressurization during launch and re-entry.  The reason for their use isn't because there's anything wrong with the air in the cabin during those times, normally.  Hypothetically, they could breath in the cabin normally during those times.  They are designed as emergency suits in case cabin pressure is lost during the extremely violent launch and re-entry phases of the mission.  If cabin pressure were suddenly lost, and they didn't have the suits on, they would asphyxiate; under the high-g-force periods of launch and re-entry, they are strapped in to their chairs anyways, so they couldn't get out and put one on.  During normal orbital flight, 1) there is basically no real stresses on the vehicle to speak of, so there's much less chance of something going wrong and 2) even if it did, the astronauts aren't strapped in to chairs and could get into their emergency suits as needed.  During launch and re-entry, you wear your emergency suit because you can't get to it if you needed it.  -- Jayron 32 17:33, 4 June 2020 (UTC)
 * You need to wear safety gear when something exciting might happen. During take off you should wear a helmet.  When you might bump into a space station you should gear up.  Between those two, when you are just coasting, it is more comfortable to wear a T-shirt and have a nap. 85.76.104.122 (talk) 17:39, 4 June 2020 (UTC)
 * This is not specific to Dragon. It's the same in Soyuz and previously Shuttle and I think Apollo and some of the Gemini flights. The reason is that not much is expected to go wrong when just coasting and as spacesuits are not very comfortable, the astronauts take them off. During launch, docking, undocking and landing, more can go wrong. A leak may appear during ascent (Challenger, although that wasn't survivable anyway), the ship can collide with the space station (Progress M-34), a valve may open prematurely (Soyuz 11), all of which may lead to depressurisation of the spacecraft. So they wear spacesuits just in case during those manoeuvres. If nothing goes wrong, the spacecraft remains pressurised, for modern spacecraft at normal atmospheric pressure. PiusImpavidus (talk) 17:49, 4 June 2020 (UTC)

Wooden vs. rubber bullets
I wonder what the material difference is? I first heard about the existence of wooden bullets a week ago in conjunction with the current disturbances. Before it had always been - rubber bullets. Are they more effective? Thanks, - AboutFace 22 (talk) 18:49, 4 June 2020 (UTC)
 * Effective at what? Putting eyes out? ←Baseball Bugs What's up, Doc? carrots→ 18:57, 4 June 2020 (UTC)
 * there are articles on these: Rubber bullet and Wooden bullet. The latter is short but it does mention it is intended to inflict Pain_compliance.  RudolfRed (talk) 21:02, 4 June 2020 (UTC)
 * Note that although the media often talk about rubber bullets, as I understand it in reality nowadays plastic bullets are very common, potentially more common at least in a number of countries. See the above linked articles and also plastic bullet along with [//www.prevention.com/health/a32729263/what-are-rubber-bullets/] [//www.reuters.com/article/us-minneapolis-police-weapons-factbox/factbox-what-us-police-are-shooting-at-protesters-idUSKBN23A30U] [//www.washingtonpost.com/opinions/2020/06/04/rubber-bullets-are-touted-safe-alternative-my-patients-wound-tells-different-story/] [//www.ncbi.nlm.nih.gov/pmc/articles/PMC5736036/] [//www.quora.com/Is-there-a-noticeable-difference-between-firing-rubber-bullets-and-live-ammunition]. Find good stats on this seems to be difficult since it isn't always clear when someone calls something a "rubber bullet" whether these are really rubber bullets (i.e. partly or completely made of something which can reasonably be called rubber natural or synthetic) or instead something which can reasonably be called "plastic" but not rubber. Nil Einne (talk) 22:16, 4 June 2020 (UTC)
 * Why don't they use potato cannons? Firing spuds is better for the environment. --Lambiam 07:27, 5 June 2020 (UTC)
 * Because the weapons need to sit in the boot of a police cruiser for years, but be ready for instant use if needed. The ammunition inside a a loaded potato cannon would rot. --Guy Macon (talk) 11:43, 5 June 2020 (UTC)
 * In the 1960s, rotten fruits were apparently a favorite hand-thrown item between groups of counter-protesters. But that's definitely a different tactic than trying to have quality-controlled ammo for firearms-type use. DMacks (talk) 14:38, 5 June 2020 (UTC)
 * Fruit-throwing has a long history as a method of assault. --47.146.63.87 (talk) 04:36, 6 June 2020 (UTC)
 * "Protesters in Columbus, Ohio reported having been shot with wooden bullets by police forces. Images online showed wooden dowel-shaped rods sliced into small, bullet-sized projectiles. The Columbus Police Department did not respond to requests for comment". Factbox: What U.S. police are shooting at protesters from Reuters. Alansplodge (talk) 11:36, 5 June 2020 (UTC)
 * And of course we believe everything protesters report, right? --15:22, 5 June 2020 (UTC)
 * Multiple news sources have reported on this (potentially lethal) use of wooden bullets. --Lambiam 11:59, 6 June 2020 (UTC)
 * As opposed to believing everything the cops report? Check the posted link. ←Baseball Bugs What's up, Doc? carrots→ 16:06, 5 June 2020 (UTC)
 * You know better than that. The fact that protestors sometimes lie does not change the fact that police officers sometimes lie.
 * I did some more research. Most police supply vendors carry less-lethal ammunition using foam, rubber, gel, beanbags, etc., but no wood projectiles, but I found one that does:
 * https://www.defense-technology.com/products/impact-munitions/
 * --Guy Macon (talk) 20:46, 5 June 2020 (UTC)
 * An image of those used by the Columbus police matches the one on the website of the Safariland Group (mission: "Together, We Save Lives™"). --Lambiam 12:36, 6 June 2020 (UTC)
 * Well it's not terribly hard to slice up some wooden dowels, which are produced to standard dimensions and can be found at any hardware store. --47.146.63.87 (talk) 04:36, 6 June 2020 (UTC)
 * Yes but you have to shoot them from a shotgun or a specialised projector, so I imagine that you would want a round that was specifically made for the purpose rather than something knocked-up in a garden shed. Bear in mind that these things can cause "death, injury and disability". Alansplodge (talk) 12:09, 6 June 2020 (UTC)


 * My search found no 12 gauge wooden projectiles. The ones I found use launchers like these: [ https://www.defense-technology.com/ShotgunTradeIn.html ] --Guy Macon (talk) 15:45, 6 June 2020 (UTC)
 * Thanks, you're right, I couldn't find any either by searching for 18.5 mm (12-guage diameter). The projectiles in your link above are 40 mm which is the NATO standard size for a grenade launcher - the British Army used to use the M79 grenade launcher for their plastic baton rounds during The Troubles. A more recent device is the Heckler & Koch HK69A1, "United States: Used by various police agencies". Alansplodge (talk) 12:39, 7 June 2020 (UTC)

Human livers now synthesized in rats.
Greetings!

I've been sporadically following the advancing of tissue engineering, and for the longest time, it seemed that only simple tissues such as skin, bone, and cartilage had been successfully synthesized. The other day, however, the online magazine Popular Mechanics reported that a research team has successfully implanted complete (albeit miniature) human livers, synthesized from the genes of donated human skin cells, inside of laboratory rats.

As I apprehend it, the liver is by far the most complicated and sophisticated organ in the human body, owing to its myriad physiological functions and unique regeneration ability. My question thus is as follows:

Will it now become easier for tissue engineers to replicate simpler human organs such as the kidney, heart, stomach, lung, and pancreas?

--Thank You!

Pine (talk) 19:10, 4 June 2020 (UTC)
 * Not an answer to your question, but I have to (violently) disagree with your statement that the liver is the most complicated organ in the body. While the liver is more complicated than say skin, it is nowhere near as complicated as the brain. (Disclaimer: I am a neurobiologist). Also, the livers were grown from cells (specifically iPSC) from human skin, not genes. Your actual question is probably an issue of WP:CBALL. Having said that, I have seen cultured human heart cells beating in a dish, and it's always a weird sight. Fgf10 (talk) 07:15, 5 June 2020 (UTC)


 * You are essentially asking for speculation, something we do not engage in. Nevertheless, it is obvious that different organs present their own, different challenges. For example, while the large-scale anatomic arrangement is not relevant for the functioning of a liver, it is essential for a working heart. How does one obtain an extracellular scaffold for a human heart? Not from a rat heart, but perhaps from a pig. Or can ways be developed to 3D-print one? Lab-growing a mini pancreas seems at the moment more in reach. The most interesting part of this research may be the successful application of techniques to differentiate induced pluripotent stem cells into various cell types, building on earlier work. Using this to create a functioning mini liver, while a tremendous feat, is mostly a proof of concept. The research suggests a way forward, but the difficulties remain formidable, and it is not clear to what extent this generalizes to other organs. BTW, the title of this thread is misleading; the livers were grown in vitro, not in rats. --Lambiam 07:20, 5 June 2020 (UTC)


 * Thank you both for your quick—and very learned—replies!
 * I apologize for my ignorance and impetuosity, but I tend to get rather excited upon witnessing such scientific advancement!


 * Pine (talk) 19:45, 5 June 2020 (UTC)