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Research Roundup

28 February 2007

Smokers found at greater risk for tuberculosis

People who smoke have a greater risk of becoming infected with tuberculosis (TB) and of having that infection turn into active TB disease, according to an analysis by Berkeley researchers published in the Feb. 26 issue of the journal Archives of Internal Medicine. After analyzing 24 studies that included details about smoking and TB outcomes, the campus team found that smokers have a 73 percent greater chance of becoming infected than do non-smokers. For those infected, the chances of developing active TB disease are about 50 percent greater in smokers. Overall, a smoker has about a 2.5 times greater risk of contracting active TB than does a non-smoker in the same population.

The results indicate that TB-control policies should incorporate tobacco control as one of the preventive interventions, the researchers said.

"Active TB is often fatal, particularly if left untreated," said Kirk Smith, a professor of environmental health sciences and senior author of the paper. "The risk factors that lead to latent TB infection becoming active are still not well understood, but this study shows that smoking is probably one of the most important. It could be that smoking suppresses the respiratory immune system, allowing latent infections to blossom. Smoking also seems to make people more susceptible to becoming infected in the first place."

- Sarah Yang

Organic molecules used to convert heat to electricity

Berkeley researchers have successfully generated electricity from heat by trapping organic molecules between metal nanoparticles, an achievement that could pave the way toward the development of a new source for energy. The discovery, described in a study published Feb. 15 in Science Express, an electronic publication of the journal Science, is being viewed as a milestone in the quest for efficient ways to directly convert heat into electricity. Currently, the dominant method of power generation involves burning fossil fuels to create heat, often in the form of steam, to spin a turbine that, in turn, drives a generator that produces electricity.

An estimated 90 percent of the world's electricity - from power plants to car engines - is created through this indirect conversion of heat. In the process, a great deal of heat is wasted and released. "If even a fraction of the lost heat can be converted into electricity in a cost-effective manner," said Arun Majumdar, professor of mechanical engineering and principal investigator of the study, "the impact it would have on energy can be enormous, amounting to massive savings of fuel and reductions in carbon dioxide emissions."

- Sarah Yang