Random Samples

Science  30 Mar 2007:
Vol. 315, Issue 5820, pp. 1773

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  1. NETWATCH: Unweaving the Rainbow

    From a rare nocturnal rainbow to a shimmering solar halo, the atmosphere can conjure up a host of surprising special effects. A general audience can learn to recognize these tricks of the light and understand their causes at Atmospheric Optics, hosted by retired chemical physicist Les Cowley of Norfolk, U.K.

    Lavishly illustrated with photos from sky watchers, the site explains atmospheric phenomena produced when light strikes water droplets, ice crystals, and dust. An early-morning shot from Mount Washington in New Hampshire, for instance, captures two sky spectacles. The photographer's outsized shadow on the mist is a Brocken specter, and the glowing rings surrounding it are a “glory.” A rainbow forms because water droplets reflect and refract light, but a glory also requires that light skid along the surface of the droplet before being refracted. Visitors can further probe the effects using free software that simulates light scattering by ice crystals and fine droplets.



    Nanotechnology is adding a new weapon to the crime fighter's arsenal: a nano-solution for sharpening fingerprints.

    For more than a century, crime investigators have sprayed suspect surfaces with a water-based gold or silver solution to detect fingerprints. The metal ions are reduced to a black precipitate along the lines of fatty deposits left by the skin ridges. But “even with the most advanced fingerprint techniques,” says chemist Joseph Almog of Hebrew University in Jerusalem, “less than a third” of good prints at crime scenes produce usable evidence.

    Almog, who is also a former chief forensic scientist for the Israel National Police, and fellow Hebrew University chemist Daniel Mandler have found that attaching hydrocarbons to gold nanoparticles is the key. The fat-seeking hydrocarbons guide the gold to the skin impression and lay down a metal trail. If this treatment is followed with the conventional solution, the gold catalyzes the precipitation of metal in solution, and the resulting fingerprints are far sharper, the scientists report in the current issue of Chemical Communications.

    The new method could be “revolutionary” for crime fighting, says Antonio Cantu, chief forensic scientist for the U.S. Secret Service in Washington, D.C. But first, says Almog, it has to be refined, standardized, and field-tested in police labs.


    An international team claims to have nailed the earliest evidence for Homo sapiens in Southeast Asia—to about 46,000 years ago.

    In 1958, excavators working at Niah Cave on the island of Borneo unearthed a skull cap and upper jaw of an anatomically modern human. Although radiocarbon dating of nearby charcoal fragments put the age at about 40,000 years, many experts suspected the skull was a newer “intrusion” into an older layer.

    View from Niah Cave. CREDIT: NIAH CAVE PROJECT

    Since 2000, researchers led by archaeologist Graeme Barker of Cambridge University in the United Kingdom have been reexamining the site. New radiocarbon dates, reported in the March issue of the Journal of Human Evolution, show that the cave was continuously occupied between 46,000 and 34,000 years ago. What's more, the group has now been able to date the skull itself, using a technique called uranium series that revealed it was up to 37,000 years old.

    The scientists contend that Niah Cave is the earliest securely dated sighting of modern humans in Southeast Asia. They also uncovered evidence that the occupants were sophisticated hunter-gatherers, hunting pigs and monkeys and detoxifying poisonous yams and nuts before eating them.

    Sandra Bowdler, an archaeologist at the University of Western Australia in Crawley, says the new dates “suggest that we can forget about the skull being from an intrusive … burial.” James O'Connell, an archaeologist at the University of Utah in Salt Lake City, adds that the work shows that the Niah Cave people's sophisticated subsistence activities “were practiced at a surprisingly early date.”



    Some fossils are rare, but this one recently unearthed in eastern Oregon may be positively mythic. In life, the 2-meter-long Jurassic seagoing crocodile (above), discovered by members of the North American Research Group, sported scales, needlelike teeth, and a fishtail. Some paleontologists, including Stanford University researcher Adrienne Mayor, think similar fossils may have inspired Native American representations of water monsters. Mayor notes the croc's “remarkable” resemblance, for example, to a 19th century Kiowa artist's drawing (inset) of a legendary water serpent.