Wikipedia:Reference desk/Archives/Science/2016 December 22

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December 22

Housekeeping in Microgravity

How do you keep air clean in microgravity, ie somewhere like the ISS? Could you centrifuge it to fling moisture particles to a water trap on the outer edge of the spinner? If you spin it really fast, could odor molecules be removed by this method? I assume toilets work by using a current of air to draw urine etc into a toilet system, how is that air seperated from the waste products, and de-odorized for re-use? If you used particulate filters to clean the air, how would you then clean the filters? Thanks in advance 49.197.186.70 (talk) 07:47, 22 December 2016 (UTC)

For the later, we have a space toilet article, and yes, urine is purified to water, and reused; it's damned expensive to get water into space. LongHairedFop (talk) 12:38, 22 December 2016 (UTC)

See also http://www.universetoday.com/101775/an-inside-look-at-the-waterurine-recycling-system-on-the-space-station/ LongHairedFop (talk) 12:43, 22 December 2016 (UTC)

See How clean is the International Space Station? and Does the ISS ever have to be cleaned? SpinningSpark 16:39, 22 December 2016 (UTC)

Space Station Kids seems to have the most comprehensive answer. SpinningSpark 16:46, 22 December 2016 (UTC)

...and for the smell issue, see How NASA Deals With Odor Inside the International Space Station. SpinningSpark 19:11, 22 December 2016 (UTC)

Thanks for those good references. OP 49.197.199.21 (talk) 23:51, 23 December 2016 (UTC)

Firing in context of measuring electrical activity in nervous sytem

What does it mean "firing" when it's mentioned in a context of measuring electrical activity in nervous system? (This is the exact text: "Measuring neuronal activity, generating action potentials, and recording the firing of individual neurons." another example: "Electrical activity of neurons is being measured. They fire prior to and at the beginning of inhalation") 93.126.88.30 (talk) 16:09, 22 December 2016 (UTC)

To "fire" is simply to generate an action potential. The term "spiking" is also used for the same thing. These terms are used solely because they are easier to say -- there is no difference whatsoever in meaning. Looie496 (talk) 15:34, 22 December 2016 (UTC)

Thank you. Then I understand it. 93.126.88.30 (talk) 16:45, 22 December 2016 (UTC)

why do the neurons in medulla oblongata fire prior to the inhalation?

"Electrical activity of neurons is being measured. They fire prior to and at the beginning of inhalation. Where are these neurons situated?" The answer is Medulla oblongata. Now my question is why do they fire prior to the inhalation? (I understand why they fire at the beginning but I don't understand why they fire prior to it)93.126.88.30 (talk) 16:44, 22 December 2016 (UTC)

Assuming these neurons initiate the inhalation cycle, they would need to fire prior to the start of the inhalation, as it takes some time for the signal the get from the brain to the lungs and diaphragm. StuRat (talk) 17:20, 22 December 2016 (UTC)

Thank you! that absolutely sounds logical. 93.126.88.30 (talk) 17:39, 22 December 2016 (UTC)