Posted: 26 Oct 2009 10:31 AM PDT
In the marvelously sensitive eyes of mantis shrimps, scientists have found cells that could inspire an overhaul of humanity's comparatively clumsy communications hardware.
Mechanical analogs of their eyes "are among the most important and commonly used optical components, and the cellular structure we describe significantly outperforms these current optics," write researchers in a study published Sunday in Nature Photonics.
Mantis shrimps are reef-dwelling marine crustaceans who trace their evolutionary lineage straight back to the Cambrian age 500 million years ago, before vertebrates had even evolved. They're so biologically unique that biologists call them "shrimps from Mars."
They possess the animal kingdom's most complicated eyes, capable of distinguishing between 100,000 colors — 10 times as many as humans — and seeing circular polarized light, or CPL, which can't be detected by any other creature.
That ability was described in a study published last March in Current Biology. In the Nature Photonics paper, researchers unveil the biological underpinning of this optical wizardry, which is performed by specialized cells arranged in tightly packed tubular bundles. The cells change the rotation of photons as they pass through, converting CPL's tight spirals to the straightforward, up-and-down wavelength of linear polarized light.
This lets mantis shrimp eyes process CPL. The same trick is performed by devices called quarter-wave plates, which convert polarized light signals inside DVD and CD players. Quarter-wave plates are also used inside satellite transmitters and other high-tech communication systems, which rely on the data-dense, loss-free transmission properties of circular polarized light.
But even our best quarter-wave plates can only detect circular polarized light in a few colors. The quarter-wave plates of mantis shrimps work across the visual spectrum, for any color of CPL. And if human engineers can mimic their designs, they might create "a new category of optical devices," the researchers write.
"The level of structural complexity and precision obtainable through natural self-assembly of biological materials far surpasses any current material manufacturing capabilities," they conclude.
Image: Flickr/Stephen Childs
"A biological quarter-wave retarder with excellent achromaticity in the visible wavelength region." By N. W. Roberts, T.-H. Chiou, N. J. Marshall and T. W. Cronin. Nature Photonics, advance online publication, October 25, 2009.
Posted: 26 Oct 2009 09:43 AM PDT
Sometimes, the sky really is falling, and other times it just seems that way.
Near the small town of Mazsalaca, Latvia on Sunday night, an object appeared to have crashed into the ground, leaving a gaping hole about more than 25 feet across. A YouTube video of the incident featured a group of excitable Latvians rushing to the hole and exclaiming their astonishment with English swear words.
But something about this presumed meteorite impact seemed fishy and conflicting reports emanated from the Baltic state about the nature of the incident. From stateside, it was impossible to tell what caused the hole just by looking at photos posted to a Latvian website.
"It could be a piece of space debris from a spacecraft, it could be a weird explosion, or it could be a meteorite," said Michael Zolensky, a meteorite specialist at NASA's Johnson Space Center. "The only way to know, though, is to dig it up."
Now that Latvian scientists are examining the scene in the light of day, it appears to be a very nerdy hoax.
"The photographs and video footage showing the crater and material in the base of it burning indicates that the alleged meteorite crater in Latvia is not an impact crater — meteorites are not 'on fire' or even hot when they land on Earth," wrote Caroline Smith, meteorite curator at the Natural History Museum, London, in an e-mail to Wired.com. "Additionally there have been no witness reports of any large 'fireball' sightings in the region on Sunday afternoon, when the crater was allegedly formed."
Latvian investigators came to a similar conclusion.
"This is not a real crater. It is artificial," Uldis Nulle, a scientist at the Latvian Environment, Geology and Meteorology Center, told the Associated Press after inspecting the site on Monday.
Another Latvian scientist said the hole in the ground was dug with a shovel.
Zolensky's colleague at Johnson Space Center, Gene Stansbury, an orbital debris specialist, said that their records do not indicate a piece of space debris scheduled for reentry into the Earth's atmosphere. NASA generally tracks objects larger than a meter in size.
A network of Air Force satellites known as the Defense Support Program do track fireballs — which a real meteorite presumably would have caused — but Wired.com has been unable to confirm whether these satellites captured anything unusual.
Update 10:30 AM PST: Added comment from Caroline Smith.
Image: Associated Press.
Via Universe Today
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