When pregnant rats are exposed to a common crop chemical, their descendants three generations later show more anxiety and stress than the offspring of unexposed peers, U.S. researchers said Monday.

The study in the Proceedings of the National Academy of Sciences suggests that the animal model may provide an explanation for the mounting number of cases of anxiety disorders, autism and obesity among humans in recent years.

Emotional stress caused by last year's tsunami caused a part of some survivors' brains to shrink, according to scientists in Japan who grasped a unique chance to study the neurological effects of trauma.

On a quest to better understand post-traumatic stress disorder (PTSD), the researchers compared brain scans they had taken of 42 healthy adolescents in other studies in the two years before the killer wave, with new images taken three to four months thereafter.

Millions of sky-gazers got the spectacle of a lifetime as a "ring of fire" solar eclipse crossed the Pacific from Asia to the United States, where it triggered whoops at festive viewing parties.

The annular eclipse was visible in western U.S. states from California to Texas late Sunday and in parts of China, Taiwan and Japan on Monday local time, making a 13,600-kilometre (8,500-mile) arc across the Pacific.

Massive extraction of groundwater can resolve a puzzle over a rise in sea levels in past decades, scientists in Japan said on Sunday.

Global sea levels rose by an average of 1.8 millimeters (0.07 inches) per year from 1961-2003, according to data from tide gauges.

The California-based company SpaceX on Saturday scrubbed the launch of its Dragon capsule toward the International Space Station at the last second due to a rocket engine problem.

The abort came a half-second before liftoff due to high pressure in the center engine of the Falcon 9 rocket, forcing a shutdown of the launch attempt. The next try is expected May 22 at 3:44 am (0744 GMT).

Japan joined the commercial space race Friday after its workhorse rocket put a paid-for South Korean satellite into orbit, pitting the country against Russia and Europe in the competition for customers.

But despite a degree of self-congratulation, space officials admitted they had to work hard to lower their prices if they were going to become truly competitive.

Special darkened glasses were selling out in Japan on Friday as anticipation built ahead of a "ring" solar eclipse above one of the most densely populated parts of the planet.

A swathe of the country will be able to see the annular solar eclipse, when the moon passes in front of the sun, blocking out all but an outer circle of light.

A Malaysian researcher known for finding new amphibian species said Friday his team had discovered at least one new species of frog in studies he said highlight Borneo's rich biodiversity.

Indraneil Das of the Universiti Malaysia Sarawak said the brown frog is just 4-5 centimeters (1.6-2.0 inches) long and makes a distinctive high-pitched chirp.

And the heat goes on. Forecasters predict toasty temperatures will stretch through the summer in the U.S. And that's a bad sign for wildfires in the West.

The forecast for June through August calls for warmer-than-normal weather for about three-quarters of the nation, the National Oceanic Atmospheric Administration said Thursday.

Scientists in the United States have enabled a paralyzed woman to lift a drink to her lips with a thought-controlled robotic arm, boosting hopes that tetraplegics may regain their independence.

On April 12 last year, 58-year-old Cathy Hutchinson made history by using only her thoughts to get a robotic arm to grasp a flask of coffee on a table, lift it and hold it to her lips for a sip, the researchers said.