Source of Asia’s Cloud

South Asia has a cloud over its head? an unpleasant, unhealthy and climate-affecting soup of sooty haze that envelops the region.

How much of the soot and other carbon- containing aerosols that make up the haze comes from the burning of fossil fuels in cars, power plants and the like, and how much comes from burning wood and other biomass for cooking and agriculture?

Orjan Gustafsson of Stockholm University and colleagues have reported in Science that the burning of biomass is the greater culprit.

The researchers used carbon-14 dating of atmospheric soot sampled in early 2006 at Sinhagad in western India and Hanimaadhoo island in the Maldives. They made use of the fact that fossil fuels are millions of years old and thus the carbon-14, a radioactive isotope with a half-life of 5,700 years, has decayed away. Vegetation that is burned when fields are cleared, and wood and dung that are used for cooking, contain“young”carbon, with plenty of C-14.

They found that biomass combustion produced about two-thirds of the pollution.

The findings suggest that controls on agricultural burning and improvements in cookstove technology could make as much of a difference, if not more, in lightening the skies over South Asia as efforts to restrict cars or build cleaner-burning power plants. HENRY FOUNTAIN

The Wrong Foot Forward


The way four-legged animals walk has been well known since the 1880s, when Eadweard Muybridge’s motion- capture photographs revealed the sequence of leg movements. The left hind leg moves forward, followed by the left foreleg, right hind leg and right foreleg, in order.

You’d think that artists, taxidermists, toy designers and others responsible for depicting animals would get it right. But a study by Gabor Horvath of Eotvos University in Hungary and colleagues shows that this is often not the case.

After analyzing more than 300 depictions of walking animals in museums, veterinary books and toy models, the researchers report that in almost half of them the leg positions are wrong.

The researchers studied only depictions where it could be determined unambiguously that the animal was walking, and not trotting or otherwise running, as in those gaits the leg movements may differ.

The researchers found that a skeleton of a dog at a Finnish museum depicts the right hindleg in a rearward position while the right foreleg is lifted and moving forward. In a proper depiction the hindleg would be forward too, having moved before the foreleg.

The researchers say that it is surprising that artists and others who provide depictions for natural history museums and textbooks are so scientifically incorrect. HENRY FOUNTAIN

Hot Liquids Ease a Cold


Like ice for a burn or a lozenge for a cough, a cup of hot tea is an age-old balm for sniffles, sneezing and stuffiness.

Hot liquids, it is said, help loosen secretions in the chest and sinuses, making them easier to expel and ultimately clearing up congestion.

The fluids are also meant to reverse dehydration.

But only recently have scientists examined whether the effect is real. In December, researchers at the Common Cold Center at Cardiff University in Britain looked at whether hot beverages relieved the symptoms of 30 people suffering from the flu or common cold any better than drinks at room temperature. They found that the contrast was marked.

“The hot drink provided immediate and sustained relief from symptoms of runny nose, cough, sneezing, sore throat, chilliness and tiredness,”they reported,“whereas the same drink at room temperature only provided relief from symptoms of runny nose, cough and sneezing.”

While this was the first study to look specifically at the effects of hot drinks on cold and flu symptoms, others have looked at hot foods like chicken soup and had similar results.

Chicken soup also contains cold-fighting compounds that help dissolve mucus in the lungs and suppress inflammation. ANAHAD O’CONNOR