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On 2015-09-23 00:11, spike wrote:<br>
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<p class="MsoNormal">So now I have a challenge for you. Write a
Hemmingway-esque story (or a you-esque story if you are better
than Papa) which will teach me something, anything. The
Hemmingway story has memorable qualities, but taught me nada.
I am looking for a short story that is memorable and
instructive, on any subject that interests you. <br>
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<br>
"Customers!"<br>
"Ah, yes, customers."<br>
"Cannot live with them, cannot live without them."<br>
"So, who?"<br>
"The optics guys."<br>
"Those are the worst."<br>
"I thought that was the security guys."<br>
"Maybe. What's the deal?"<br>
"Antireflective coatings. Dirt repelling."<br>
"That doesn't sound too bad."<br>
"Some of the bots need to have diffraction spread, some should not.
Ideally determined just when hatching."<br>
"Hatching? Self-assembling bots?"<br>
"Yes. Can not do proper square root index matching in those. No
global coordination."<br>
"Crawly bugbots?"<br>
"Yes. Do not even think about what they want them for."<br>
"I was thinking of insect eyes."<br>
"No. The design is not faceted. The optics people have some other
kind of sensor."<br>
"Have you seen reflections from insect eyes?"<br>
"If you shine a flashlight in the garden at night you can see
jumping spiders looking back at you."<br>
"That's their tapeta, like a cat's. I was talking about reflections
from the surface."<br>
"I have not looked, to be honest."<br>
"There aren't any glints when light glance from fly eyes. And dirt
doesn't stick."<br>
"They polish them a lot."<br>
"Sure. Anyway, they have nipples on their eyes."<br>
"Nipples?"<br>
"Nipple like nanostructures. A whole field of them on the cornea."<br>
"Ah, lotus coatings. Superhydrophobic. But now you get diffraction
and diffraction glints."<br>
"Not if they are sufficiently randomly distributed."<br>
"It needs to be even density. Some kind of Penrose pattern."<br>
"That needs global coordination. Think Turing pattern instead."<br>
"Some kind of tape?"<br>
"That's Turing machine. This is his last work from '52,
computational biology."<br>
"Never heard of it."<br>
"It uses two diffusing signal substances: one that stimulates
production of itself and an inhibitor, and the inhibitor diffuses
further."<br>
"So a blob of the first will be self-supporting, but have a moat
where other blobs cannot form."<br>
"Yep. That is the classic case. It all depends on the parameters:
spots, zebra stripes, labyrinths, even moving leopard spots and
oscillating modes."<br>
"All generated by local rules."<br>
"You see them all over the place."<br>
"Insect corneas?"<br>
"Yes. Some Russians catalogued the patterns on insect eyes. They got
the entire Turing catalogue."<br>
"Changing the parameters slightly presumably changes the pattern?"<br>
"Indeed. You can shift from hexagonal nipples to disordered nipples
to stripes or labyrinths, and even over to dimples."<br>
"Local interaction, parameters easy to change during development or
even after, variable optics effects."<br>
"Stripes or hexagons would do diffraction spread for the bots."<br>
"Bingo."<br>
<br>
<br>
<div id="gs_cit1" tabindex="0" class="gs_citr">Blagodatski, A.,
Sergeev, A., Kryuchkov, M., Lopatina, Y., & Katanaev, V. L.
(2015). Diverse set of Turing nanopatterns coat corneae across
insect lineages. <i>Proceedings of the National Academy of
Sciences</i>, <i>112</i>(34), 10750-10755.</div>
<a class="moz-txt-link-freetext" href="http://www.pnas.org/content/112/34/10750.full">http://www.pnas.org/content/112/34/10750.full</a><br>
<br>
<br>
<br>
<pre class="moz-signature" cols="72">--
Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University</pre>
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