Seabirds Can Navigate by Smell
Albatrosses, petrels and other "tube-nosed" seabirds can fly thousands of miles over open ocean and navigate back to their nests on tiny, remote islands. But how? A pair of studies on Antarctic prions -- tube-nosed seabirds that feed on crustaceans, sea worms and small fish -- suggests these birds use a refined sense of smell to keep track of where they are over a seemingly featureless sea.
Gabrielle Nevitt of the University of California at Davis has long suspected that tube-nosed birds can detect differences in the concentrations of dimethyl sulfide (DMS) in the air above stretches of the ocean's surface. The gas is a byproduct of decaying fish and plankton and has been shown to linger over biologically productive patches of ocean at concentrations too weak to be smelled by humans.
Nevitt's latest work, conducted with French behavioral ecologist Francesco Bonadonna, offers two findings supportive of her theory. In one experiment, 10 birds were fitted with portable electrocardiogram devices, which showed that the birds' heartbeats increased significantly when the air they were provided was laced with DMS at concentrations found at sea. In the other, prions placed in a maze of tubes big enough to walk through chose paths filled with air spiked with the same low concentrations of DMS, indicating the birds can not only detect the gas but also navigate toward it.
The experiments provide the first physiological evidence that the birds can make navigational use of the oceans' "olfactory landscape," the team reported in the online version of Biology Letters, a publication of the Royal Society.
-- Rick Weiss
Catchers Suffer Impact Most
For Little Leaguers who long ago deduced that playing catcher could be hazardous to your health, there is news: Catching baseballs -- especially baseballs thrown at upwards of 90 mph for nine innings or so -- is not good for the hands.
In a study of 36 Class A Carolina League minor-leaguers, orthopedic surgeons from Wake Forest University's Baptist Medical Center found that nearly half the catchers (44 percent) reported "weakness" in the gloved hand, compared with 17 percent of infielders and outfielders and 7 percent of pitchers. This, despite the fact that eight of the nine catchers polled used extra padding -- usually batting gloves.
"A significant percentage had problems with arteries in their hand and enlarged fingers," said Wake Forest hand surgeon L. Andrew Koman, a co-author of the study, in the current issue of the American volume of the Journal of Bone and Joint Surgery. "They also report weakness, pain and tingling."
The research team also conducted tests to discern abnormalities in blood flow caused by repeated impacts. Koman said ballplayers in general appeared to have a high rate of hand trauma, but catchers suffered most.
The researchers estimated that each day catchers catch at least 150 balls traveling 80 to 100 mph. Most impacts are concentrated at the base of the index finger of the catching hand.
Koman said researchers could offer no immediate solution beyond somehow "fixing the gloves." He suggested that baseball players should see doctors but did not hold out much hope: "These guys are tough. And this is what they do."
-- Guy Gugliotta
Drug Counters Autism's Effects
The antipsychotic drug Risperdal decreased tantrums, aggression and self-injurious behavior among children with autism in a small study funded by the government.
This is the first time that any drug from a relatively new class of medications called atypical antipsychotics has been systematically studied in autistic children.
"The response to [Risperdal] ranks among the most positive ever observed in children with autism for a drug treatment," said study investigator James McCracken, a professor of psychiatry and biobehavioral sciences at the University of California at Los Angeles. The study was published last week in the American Journal of Psychiatry.
But the drug was not superior to a placebo in improving language skills and social relatedness -- two problems symptomatic of the disorder -- among autistic children. Researchers found some signals, however, that the drug might help with their social deficits, perhaps because reducing tantrums and aggressive behavior allowed the children "to be more available for social interaction."
The drug was also superior to placebos in reducing repetitive behaviors -- another hallmark of autism -- among the children.
The study, sponsored by the National Institute of Mental Health, evaluated the benefits of the drug over sugar pills among 63 autistic children for eight weeks. Researchers found the benefits persisted for as long as six months.
-- Shankar Vedantam