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Friday, 03 February 2012

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Suriname forest reveals 46 new species

A "cowboy frog" and a "crayola katydid" are among 46 new species that have been discovered in the dense forests of the tiny South American nation of Suriname, scientists said recently.
The caramel-coloured frog displays white fringes along its back legs and a spur on its heels, while the unusual katydid earned its nickname from the striking hues on its body and wings. Other discoveries included a two-inch (five-centimeter) catfish, and larger catfish covered with a spiny armour to protect it against predators in the piranha-filled river.
The findings were made by an expedition of international scientists, indigenous people and university students as part of a three-week river expedition organized by Conservation International.
The journey took them along the Koetari and Sipaliwini rivers, where they also found intriguing new rock carvings, or petroglyphs, along the border with southern neighbour Brazil.
"As a scientist it's exciting to do research in such remote areas where countless new discoveries await you," said Trond Larsen, director of the Rapid Assessment Programme survey for Conservation International.
The petroglyphs were found on caves near the Trio village of Kwamalasamutu, a site that Conservation International is helping local communities preserve as an ecotourism destination.
In 2000, Werehpai cave petroglyphs were discovered in the same area and scientists believe it is the oldest known human settlement found in southern Suriname.
Radiocarbon dating and archaeological studies suggest that the first signs of habitation go back at least 5,000 years.
According to Conservation International Suriname director Annette Tjon Sie-Fat, the findings will play a vital role in preserving and managing the area as a cultural heritage site and as unique destination for tourists.
The environmental group hopes the Suriname government will develop laws to protect the country's biodiversity, in order to preserve untouched areas and prevent them from being given away as concessions for mining or timber.
In 2007 a similar expedition in Suriname resulted in the discovery of 24 new animal species.
AFP

Novel material takes 3D 'invisibility cloak' closer
Richard  Ingham

Scientists in the United States reported a further step towards a celebrated "invisibility cloak" by masking a large, free-standing object in three dimensions.
The lab work is the latest advance in a scientific frontier that uses novel materials to manipulate light, a trick that is of huge interest to the military in particular.
Reporting in the New Journal of Physics, researchers at the University of Texas in Austin cloaked an 18-centimetre (7.2-inch) cylindrical tube from light in the microwave part of the energy spectrum. Those hoping for a Harry Potter-style touch of wizardry would be disappointed. To the human eye, which can only perceive light in higher frequencies, no invisibility would have been seen.
But, say the researchers, the experiment is important proof of a principle that so-called plasmonic meta-materials can achieve a cloaking effect. A warplane cloaked with such materials could achieve "super-stealth" status by becoming invisible in all directions to radar microwaves, said co-lead investigator Andrea Alu.
Plasmonic meta-materials are composites of metal and non-conductive synthetics made of nanometre-sized structures that are far smaller than the wavelength of the light that strikes them.
As a result, when incoming photons hit the material, they excite currents that make the light waves scatter.
The new experiment entailed making a shell of plasmonic meta-materials and placing the cylinder inside, and exposing the combination to microwaves.
Microwaves scattered by the shell ran into microwaves bounced from the object, preventing them sending a return signal to the viewer. "When the scattered fields from the cloak and the object interfere, they cancel each other out, and the overall effect is transparency and invisibility at all angles of observations," said Alu.
Any shape of object can be masked, he added. The cloaking worked best at a microwave frequency of 3.1 gigahertz, said the paper. The feat is a step forward because other techniques have entailed bending light around two-dimensional objects or, in 3D, masking microscopic bumps on mirrors or reflectors, an approach called "carpet cloaking," say the authors.
The new concept could be modified for visible light, although any cloaked objects would be very small, in the micrometer range, as the plasmonic effect is linked to the wavelength of the light, Alu said in a phone interview.
AFP