Recent comments in /f/askscience

NimdokBennyandAM t1_j426w6o wrote

Reply to How do giraffes breathe? by NimishApte

Long neck, but narrow; massive lungs, 8x the size of a human's; a strong heart that gives it blood pressure twice that of a human's; and a respiration rate 1/3 as slow as a human's.

Essentially: their throat will fill with dead air; it's too big not to. But, their lungs are huge, and they have a respiration rate 1/3 the speed of a human's, sucking as much oxygen out of their air as possible. Their cavernous lungs and ability to sip oxygen out of them, plus their hard-beating heart's ability to efficiently spread that O2 all over their bodies, mitigates the threat of dead air build-up in their throat.

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srandrews t1_j425bdp wrote

Reply to How do giraffes breathe? by NimishApte

As I recall from my human physiology class, it is called tidal volume. The game is to be able to have more volume in the lungs than the trachea. And that is pretty easy to do. Giraffes do have pretty big chests. And the next area to think about is the rate of ventilation. One is able to test this for themselves. How long can nominal breaths be skipped before needing a full breath to recover? You can go for a pretty long time taking every other. So that indicates that a single breath may have more O2 than needed as well as the capacity to take CO2. And so partial mixing of the last and next breath works. It is surprisingly complex.

As far as pressure, outside and inside the giraffe are the same pressure. And so it is a matter of muscles moving gas in a manner similar to a billows. But the diaphragm does the work via a pressure differential by expanding and contracting the chest cavity causing the pluera that contains the lungs to pull the lungs open.

What is cool is if you breathe sulfur hexafluoride, it is heavier than air. And so it doesn't mix. And it is difficult if not possible to ventilate. And so drowning! Unless you hang yourself upside down.

That is the extent of my recollection of that chapter. Good Q! Hope someone more up to date can correct me.

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SamQuan236 t1_j41x85j wrote

Reply to Why is the rare moon halo perfectly round? by Supreme_MangoKat

You are seeing the effects of polycrystalline diffraction. If you were to pass the light through a single crystal, you would see something like a spot or line pattern (kikuchi bands).

Because the orientation of the ice crystals are random in the atmosphere, you get a random orientation during the light scattering. summing up all these many spot patterns from each individual scattering at random rotations gives you a ring.

You could emulate the process with a stencil of dots at whatever pattern you like. Rotate it randomly and then draw in the dots from the stencil. If you do this enough, you will get a ring.

Technically there are many processes going on. Single scattering (which produces the dot pattrn) requires very small amounts of material. As the material (here ice) gets thicker, you will see lines forming (multiple scattering).

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mistermoondog t1_j41wfbf wrote

Reply to comment by mtv2002 in Why do poultry producers kill their stock when they get bird flu, rather than keeping survivors to reproduce? by poorbill

Thank-you for your detailed backing information. I had no idea your industry had so many precautions—for the longest time it seems the only “press” your sector got was reduced profits paid by the mega-chicken-processors based in Arkansas. My 1st Pandemic inoculation was 1968/Hong Kong flu. I pictured, in my head, some weird virus spontaneously appearing in some broken-down pre- 20th century poultry farm.

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