Ghost pains, it seems. Why do some people still feel discomfort long after their injuries have healed?

The definitive answer -- and an effective treatment -- has long eluded scientists. Traditional analgesic drugs, such as aspirin and morphine derivatives, haven’t worked very well.

A Northwestern University researcher has found a key source of chronic pain appears to be an old memory trace that essentially gets stuck in the prefrontal cortex, the site of emotion and learning. The brain seems to remember the injury as if it were fresh and can’t forget it.

University of Utah physicists developed small devices that turn heat into sound and then into electricity. The technology holds promise for changing waste heat into electricity, harnessing solar energy and cooling computers and radars.

"We are converting waste heat to electricity in an efficient, simple way by using sound," says Orest Symko, a University of Utah physics professor who leads the effort. "It is a new source of renewable energy from waste heat."

Southeastern Brazil, South America’s largest and most populous country, is highlighted in this 26 May 2007 Envisat image.

Brazil consists of one federal district and twenty-six states, four of which comprise the southeastern region – Rio de Janeiro, Minas Gerais, Sao Paolo (all visible) and Espirito Santo.

The huge potential of agricultural soils to reduce greenhouse gases and increase production at the same time has been reinforced by new research findings at NSW Department of Primary Industries' (DPI) Wollongbar Agricultural Institute.

Trials of agrichar - a product hailed as a saviour of Australia's carbon-depleted soils and the environment - have doubled and, in one case, tripled crop growth when applied at the rate of 10 tonnes per hectare.

Albert Einstein’s theory of general relativity has fascinated physicists and generated debate about the origin of the universe and the structure of objects like black holes and complex stars called quasars. A major focus has been on confirming the existence of the gravitomagnetic field, as well as gravitational waves.

A physicist at the University of Missouri-Columbia recently argued in a paper that the interpretation of the results of Lunar Laser Ranging (LLR), which is being used to detect the gravitomagnetic field, is incorrect because LLR is not currently sensitive to gravitomagnetism and not effective in measuring it.

The discovery of how some abnormal cells can avoid a biochemical program of self-destruction by increasing their energy level and repairing the damage, is giving investigators at St. Jude Children's Research Hospital insights into a key strategy cancer cells use to survive and thrive.

The finding offers an explanation of how abnormal cells that have cheated death once by disabling the main suicide pathway called apoptosis can also foil a backup self-destruct program, which allows them to survive and become cancerous.