-- A star like our sun, 4,000 light-years from earth, undergoes a colorful demise in this image, captured by the Hubble Space Telescope's Wide Field Planetary Camera 2. The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star's remaining core. Ultraviolet light from the dying star makes the material glow. The burned-out star, called a white dwarf, is the white dot in the center. Our sun will eventually burn out and shroud itself with stellar debris, but not for another 5 billion years. The colors correspond to material expelled by the star: Blue is helium, blue-green is oxygen, and red is nitrogen and hydrogen.
(K. Noll/NASA/ESA)
DISCOVERIES
Chili peppers on the menu for at least 6,000 years
ARCHEOLOGY
The cultivation of chili peppers originated in the Americas about 6,100 years ago, a new study finds. Every plant species has its own characteristic starch grain -- like a fingerprint -- that can be used as a marker to identify the plant species. Now, by routinely analyzing fossilized starch samples from seven archeological sites in Central and South America, researchers have identified the distinctive starch microfossil for chili peppers, and unintentionally documented the history of the peppers from about 6,000 years ago to 500 years ago. The researchers, led by Linda Perry of the Smithsonian National Museum of Natural History, also found that starch microfossils from chili peppers and from maize coexisted, which means the two plants "traveled" together in the tropics just like the corn-beans-squash trio did in North America.
BOTTOM LINE: Though researchers knew that chili peppers were important in many ancient cuisines, they had not known the origin and domestication history of these plants. "We now have the starch microfossil marker for chili peppers and we can trace its use in ancient American cuisines," said Perry.
CAUTIONS: More work is required to clearly establish the earliest dates and specific regions associated with the origin of chili peppers and their evolution with society.
WHAT'S NEXT: In future projects, researchers hope to document exactly when chili peppers were first used and first domesticated. They also hope to identify the distinctive starch microfossils of the five different Capsicum species -- which include jalapenos, bell peppers, and anaheims. So far Perry has identified only one -- that of the hot rocoto pepper still grown in the Peruvian highlands.
WHERE TO FIND IT: Science, Feb. 16.
SENA DESAI GOPAL
BACTERIA
Ability to swim upstream may explain infections
Under the right conditions, E. coli can swim upstream, a recent Yale University study found, perhaps explaining why hospital patients with catheters are so susceptible to infection. The bacteria were able to swim upstream in a catheter or other tube, the researchers found, if the speed of the liquid flowing through the tube was slow enough. They stayed near the edge of the tube to take advantage of the slower fluid velocity there, said Jane Hill, a postdoctoral student in Yale's environmental engineering program and co-author of the report. The fluid dynamics that govern the upstream movement apply to everything from human urinary tracts to drinking water supplies. According to the findings, speeding up the flow of liquid through irrigation pipes might help contain future outbreaks of deadly E. coli.
BOTTOM LINE: Bacteria's swimming ability may explain why patients with catheters are so vulnerable to infection -- and also suggests some ways to solve the problem.
CAUTIONS: The study only looked at E. coli, although the team believes its results should apply to anatomically similar microbes.
WHAT'S NEXT: Future studies will examine how fluid velocity and other fluid dynamics work in real world settings, such as irrigation systems and catheterized patients.
WHERE TO FIND IT: Physical Review Letters, early online, Feb. 6
J.M. BERGER 
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