Teens who spend more time watching television or using computers appear to have poorer relationships with their parents and peers, according to a report in the March issue of the Archives of Pediatrics and Adolescent Medicine.

Given the importance of healthy relationships with friends and family to adolescent development, the researchers suggest that "concern about high levels of screen time among adolescents is warranted" and that more research is needed to monitor the effects of new technologies on the well being of growing teenagers.

Despite research suggesting that sodium reduction would do little to improve public health, scientists writing in the Annals of Internal Medicine say  that a voluntary effort by the U.S. food service industry to reduce salt in processed foods could have far-reaching implications for the health of the U.S. population, preventing strokes and heart attacks in nearly a million Americans and saving $32.1 billion in medical costs.

Scientists writing in the FASEB Journal say a genetically modified strain of tobacco can help temper the damaging effects of toxic pond scum, known as microcystin-LR (MC-LR), which makes water unsafe for drinking, swimming, or fishing. The plant could serve as a major tool for helping keep water sources safe to use, especially in developing nations.

The new strain was developed by inserting genes which code for the production of an antibody called MC-LR. With the genes in place, the new strain of tobacco produced the antibody in its leaves and secreted it from its roots into the surrounding hypotonic growth medium.

A new study in Nature Geoscience suggests that an asteroid strike may not only account for the demise of ocean and land life 65 million years ago; the resulting dust, darkness and toxic metal contamination may also explain the geographic unevenness of extinctions and recovery.

Using 823 samples from 17 drilling sites in both the Northern and Southern Hemispheres, researchers analyzed the community structure of calcareous nannoplankton. Included in their study were two sites -- one in the Pacific and one in the South Atlantic -- with reliable, accurate dating.

The longer an individual uses marijuana, the more likely that person is to meet criteria for psychosis, according to a report to appear in the May print issue of the Archives of General Psychiatry. Previous studies have identified an association between cannabis use and psychosis, but the authors of the current study say concerns remain that earlier research has not adequately accounted for confounding variables.

Geologists at the Woods Hole Oceanographic Institution (WHOI) say the massive, 8.8-magnitude earthquake that struck Chile last week occurred in an offshore zone that was under increased stress caused by a 1960 magnitude 9.5 earthquake.

 Some 300-500 times more powerful than the magnitude 7.0 quake in Haiti Jan. 12,  the earthquake ruptured at the boundary between the Nazca and South American tectonic plates. The temblor was triggered when the "subducting" Nazca plate was thrust under the South American plate, uplifting a large patch of the seafloor and prompting tsunami warnings throughout the Pacific Ocean. The two plates are converging at a rate of 80 mm per year, says WHOI geologist Jian Lin, "which is one of the fastest rates on Earth."