UPI NewsTrack Health and Science News

New microscope can color-code atoms

ITHACA, N.Y., Feb. 25 (UPI) -- A new electron microscope at Cornell University is enabling scientists for the first time to form color-coded images of individual atoms.

"The current generation of electron microscopes can be thought of as expensive black-and-white cameras where different atoms appear as different shades of gray," said Cornell Associate Professor David Muller. "This microscope takes color pictures -- where each colored atom represents a uniquely identified chemical species."

The instrument is a new type of scanning transmission electron microscope built by the Nion Co. of Kirkland, Wash., under an instrument-development award to Cornell from the National Science Foundation. Professor John Silcox and Ondrej Krivanek of Nion are the project's co-principal investigators.

The microscope incorporates new aberration-correction technology that focuses a beam of electrons on a spot smaller than a single atom and does it more sharply and with greater intensity than previously possible. That, the scientists said, allows information previously hidden in the background to be seen. It also provides up to a hundredfold increase in imaging speed.

The capabilities of the new instrument are described in the journal Science.

Yellow fever outbreak reported in Paraguay

WASHINGTON, Feb. 25 (UPI) -- Health officials reported an outbreak of yellow fever in Paraguay, with seven confirmed cases in San Pedro and four as yet unconfirmed cases in San Lorenzo.

In addition, Africa Fighting Malaria -- a non-profit health advocacy group based in South Africa and in Washington -- said the number of cases reported by neighboring Brazilian health authorities has more than quadrupled during the past two months, with 13 deaths reported.

Yellow fever is a viral disease transmitted by mosquitoes. Although a vaccine exists, there is no cure for the disease that infects about 200,000 people annually.

"As with malaria, the yellow fever outbreaks highlight the urgent need for carefully controlled insecticide spraying programs," said Richard Tren, director of Africa Fighting Malaria. "These programs should have been strengthened to sustain progress.

"Decades of anti-insecticides pressure culminated in 1997 when the World Health Assembly passed a resolution to reduce the use of insecticides in disease control," added Tren. "The resurgence of yellow fever is an unfortunate consequence of that resolution."

The World Health Organization said it has sent 4 million doses of vaccine to Paraguay, along with an epidemiologist, virologist and other emergency management experts.

Study: Dust increasing over western U.S.

BOULDER, Colo., Feb. 25 (UPI) -- University of Colorado-Boulder scientists said western U.S. states have become 500 percent dustier during the past two centuries because of human activity.

Sediment records from dust blown into alpine lakes in southwest Colorado's San Juan Mountains over millennia indicates the sharp rise in dust deposits coincided with railroad, ranching and livestock activity in the middle of the last century, said geological sciences Assistant Professor Jason Neff, lead author of the study. The results have implications ranging from ecosystem alteration to human health, he said.

"From about 1860 to 1900, the dust deposition rates shot up so high that we initially thought there was a mistake in our data," said Neff. "But the evidence clearly shows the western U.S. had its own Dust Bowl beginning in the 1800s when the railroads went in and cattle and sheep were introduced into the rangelands."

The research that included CU-Boulder's Ashley Ballantyne, Lang Farmer and Corey Lawrence; Cornell University's Natalie Mahowald; the University of Arizona's Jessica Conroy and Jonathan Overpeck' Christopher Landry of the Center of Snow and Avalanche Studies in Silverton, Colo.; the University of Utah's Tom Painter and the U.S. Geological Survey's Richard Reynolds appears in the journal Nature Geoscience.

Scientists film an electron for first time

LUND, Sweden, Feb. 25 (UPI) -- Swedish scientists have filmed an electron for the first time, showing it riding on a light wave after just having been pulled away from an atom.

Lund University researchers used a newly developed technology for generating short pulses from intense laser light -- so-called attosecond pulses -- to capture an electron's motion for the first time.

"It takes about 150 attoseconds for an electron to circle the nucleus of an atom," said Lund Assistant Professor Johan Mauritsson. An attosecond is one quintillionth of a second.

"We have long been promising the research community that we will be able to use attosecond pulses to film electron motion," said Mauritsson, who co-led the study with Professor Anne L'Huillier. "Now that we have succeeded, we can study how electrons behave when they collide with various objects."

The accomplishment is reported in the journal Physical Review Letters.