Science briefing: Darkening skies

By Clive Cookson
Published: March 13 2009 14:58

Skies have dimmed over most of the world during the past 35 years as a result of increasing pollution, according to a comprehensive study published on Friday in Science. The shining exception is Europe, where skies are clearer.
Scientists at the University of Maryland analysed visibility measurements over the period 1973 to 2007 from weather stations all over the world and also studied more recent satellite data. Visibility - the furthest distance a trained meteorological observer can see - is reduced by microscopic particles of soot and dust and droplets of sulphur dioxide in the air; these “aerosols” are generated by burning fossil fuels.
The greatest reductions in visibility - or “dimming” - occurred over rapidly industrialising regions of south and east Asia. Africa, Australia and south America have also experienced some dimming. Europe was the only continent where the sun shone brighter in 2007 than in 1973.
Although the effects are not large - the average global dimming rate is about 0.1 per cent a year - scientists say the aerosols responsible are bound to play a role in climate change. More research will be needed to determine whether dimming is accelerating or putting a brake on global warming.
Boost for electric cars
Engineers at Massachusetts Institute of Technology have discovered how to boost the performance of lithium-ion batteries, a favoured power source in applications from laptop computers to electric cars. Their research, described in the journal Nature, will allow lithium batteries to be discharged and recharged much more quickly than is possible today.
Lithium cells are popular because of their high energy density - they can store a lot of charge in a small space - but their charging and discharging rates are relatively slow. By redesigning the battery and incorporating a compound called lithium iron phosphate, the MIT researchers made a prototype cell that could be fully charged and discharged within 20 seconds; the process takes six minutes in a conventional cell of the same size.
“The ability to charge and discharge batteries in a matter of seconds... may open up new technological applications and induce lifestyle changes,” Gerbrand Ceder and Byoungwoo Kang of MIT conclude in their Nature paper.
Electric cars powered by the new batteries could not only be recharged quickly but would also accelerate faster. MIT says the research has been licensed to two companies and could be on the market within three years.
CJD hopes dimmed
The first clinical trial of a treatment for Creutzfeldt-Jakob disease has given mainly disappointing results.
Laboratory tests and anecdotal evidence from patients had raised hopes that quinacrine, a medicine used to treat malaria and arthritis, might help people with CJD. This fatal brain disease occurs spontaneously in around two people per million but it has also affected around 200 people who ate beef contaminated with BSE (mad cow disease) before controls were imposed in the 1990s.
John Collinge of University College London organised a trial for the UK Medical Research Council with 107 CJD patients, of whom 40 took quinacrine and 67 did not. Although mortality was slightly lower in the group taking the drug, there was no significant difference in survival after adjusting for factors such as disease severity.
A mildly encouraging sign was that the four patients who had temporary improvements in brain function during the trial were all in the group taking quinacrine.
In a comment accompanying Prof Collinge’s paper in Lancet Neurology, Michael Geschwind of the University of California, San Francisco, says it is unlikely that quinacrine will be the “penicillin” for CJD. But he adds: “The results of this study show that treatment trials for rare, rapidly progressive and fatal diseases are possible.”
Copyright The Financial Times Limited 2009