Which is how we got coal in the first place. 
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I wonder if this explains ⌠well, a lot about how noise has such different effects on different people.
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Fascinating article. I recall an early (i.e., ~1970) acoustic traffic detector at a stoplight that used ultrasound â and I mean blasting. I guess it died a deserved death.
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I got to watch this technology up close while at the FDA. Whatâs interesting is that you donât take out the old failing valve; you just inflate a balloon within it (stretching the old valve out), and then deploy the new valve within it. That means the new valves sits within the old valve. Seems to work pretty well.
The possibly untrue part (in my opinion) is the âyounger patients may not need open-heart surgery.â Valves inserted via catheter (instead of open-chest surgery) are tissue valves, and only last 10-15 years. So, if youâre younger, what do you do when the new valve fails? You can just stick another one in, within the failed tissue valve thatâs already within the natural valve. So that would be three layers of valve. Hmm. Then what if that one fails also? Valve within valve within valve within valve?
Sometimes the clinician (not a surgeon, btw) who puts one of these in has trouble with it. It doesnât deploy properly, or it gets put in backward (that really happened!). They canât take it out, because you canât squish back it down to take it out by catheter. So the clinician will put another one in, inside the first one, which is inside the patientâs failed valve.
Or do you just go back to open-heart surgery, when youâre that much older?
I first heard about these back in 2003, when it was still very early research. I forget exactly when they were first approved for older people and people who were too sick for surgery.
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Really cool!
Anyone know what the color codes for in this simulation?
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http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20190318
has a film of the presentation. All the nice blacks are now shades of grey, as if someone just pointed a camera at the projector screen.
That particular n-body simulation is discussed around 35minutes in. The colors denote maximum acceleration-- blue is least acceleration, red is most acceleration.
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Thanks!
There has been a couple bits of news about comb jellies recently. For background, these are kind of jellyfish-like animals, but they donât have any stings or do the whole pulsating thing. Most swim with special combs and either have sticky tentacles or eat things whole. Here are some examples:
Like jellyfish and their relatives, comb jellies plainly split off back when animals were relatively simple, but placing them has been difficult. There were even some studies which showed they diverged before sponges, which would mean that either comb jellies invented things like nerves on their own, or that sponges actually had and lost them. Iâm not sure thatâs held up though.
Anyway, itâs tricky is knowing what features are actually inherited in common, and what might be convergence or superficial similarity. For instance, whereas jellyfish have a single gut opening, comb jellies are supposed to have a one-way gut like us; but that might have a separate origin. And for that, thereâs an interesting new finding that at least some comb jellies are intermediate, with one or two openings as needed:
The biggest problem with comparing comb jellies, though, is that what we have isnât actually an ancient lineage. All the living types are part of a single group that only goes back to the end of the Mesozoic, so they could be a very specialized group. You can imagine trying to work out vertebrate evolution knowing about mammals but not fish.
This week there is a new study on Cambrian fossils from China, though, that identifies some of the fossils as having ciliate structures akin to combs. They interpret them as some of the earliest members of the comb jelly lineage, and provide a sketch of how they changed from anemone-like things to their modern forms:
https://www.cell.com/current-biology/fulltext/S0960-9822(19)30206-4
If itâs true, I think thatâs not just a good step toward settling early animal relationships, but also the first time Iâve seen a story for how these strange creatures actually came about.
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I love the blinky lights â is that an optical effect or bioluminescence?
We visited the Monterey Bay Aquarium once and it was fabulous. I believe thatâs where we saw an exhibit of more typical jellyfish (but it may have been at another aquarium). We still have a jellyfish sweatshirt from that exhibit.
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I super love this question because I fundamentally donât think itâll ever be resolved, and people get so worked up over it.
Bioluminescence. If youâre in New England, youâll see these dudes getting dashed on rocks and luminescing as they die. If youâre in Mass or RI or something, right off the coast at night is like swimming in outer space. Wave your arms in the water and they light up in alarm.
Iâm a mean drunk, BTW.
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Most comb jellies are bioluminescent, with a faint bluish glow. But the blinky lights are an optical effect from the cilia on the combs. My understanding is the distance between the cilia is on the same order as the wavelength of visible light, but changes as they row, creating this beautiful shifting iridescence.
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Iridescence was my first guess, because of all the different colors, and the high rate of change. You can kind of see the movement of the cilia. But the fact that the beast as a whole glows is cool too.
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unfortunately, all too true
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