Doctors faulted for flying

Here’s a conundrum for medical practitioners. Doctors who fly around the globe to attend professional meetings are violating the Hippocratic admonition to “do no harm” by unnecessarily contributing to carbon emissions, global warming and risks to human health.

Here’s a conundrum for medical practitioners. Doctors who fly around the globe to attend professional meetings are violating the Hippocratic admonition to “do no harm” by unnecessarily contributing to carbon emissions, global warming and risks to human health. At least that is the conclusion of two British physicians who analysed data on professional travel. Ian Roberts, an epidemiologist at the London School of Hygiene and Tropical Medicine, and Fiona Godlee, an editor at the British Medical Journal, noted in the February 17 issue that climate change posed a threat to human health through anticipated increases in malnutrition, disease and flooding. They quantified the irony by citing a recent study, which calculated that the 17,000 delegates at a European Respiratory Society conference last year in Munich generated 4,000 tonne of carbon dioxide from travel alone. Another study found that the 15,000 delegates who flew to the American Thoracic Society meeting in San Diego this month generated nearly 11,000 tonne of carbon dioxide—about the amount produced in a year by 550 Americans—or 110,000 people in the African nation of Chad. Combined with research that has found scant evidence that attendance at such meetings has much impact on the quality of patient care—and the widely accepted but little-talked-about recognition that most such trips are “free lunches” in which doctors get free trips to nice locales in return for delivering 15-minute talks—the team suggested that more conferences should be virtual, with video links for far-flung “attendees.” – LAT-WP

A world built for right-handers

As with humans, where right-handers far outnumber left-handers, among most snail species right-handed shells are predominant. That is, when looked at from above (with the spire pointing up), most shells are “dextral,” spiraling in a clockwise direction. “Sinistral,” or counterclockwise, shells are rare. Masaki Hoso of Kyoto University in Japan and colleagues report that this directionality has had an effect on snail-eating snakes of the subfamily Pareatinae. In a paper in Biology Letters, the researchers describe how the jaws of these snakes have evolved so the right mandible has more teeth than the left, and how the snakes have a much easier time eating a dextral snail than a sinistral one. The researchers studied the feeding behavior of one member of the subfamily, Isawaki’s snail-eating snake. It clamps onto the outside of the shell with its upper jaw, reaches in with its bottom jaw and alternately retracts the left and right mandibles to work the snail out. With a dextral snail this all happens fairly easily. The snake approaches the snail from behind, turns its head so that the upper jaw clamps on to the inner side of the shell (the side opposite the spire) and after retracting its mandibles for a couple of minutes successfully extracts the snail and swallows it. But with a sinistral snail, the upper jaw tries to clamp down on the outer, spire side of the shell (which flares outward), and has a much more difficult time. The snakes take far longer to handle a sinistral snail, requiring more mandible retractions. And they often make a total hash of it, dropping the snail or otherwise failing to eat it. – NYT

It can’t be too thin

Synthetic membranes designed to separate proteins and other molecules have an inherent problem. While their pores may be of the proper diameter, on the order of 10 nanometers, or 10 billionths of a meter, the membranes are too thick — perhaps a thousand times as thick as the molecules they are meant to filter. That can reduce efficiency and make filtration a slow process. Now Christopher C. Striemer and colleagues at the University of Rochester report success in fabricating an extremely thin membrane. They say it may prove useful in identifying or separating proteins or other molecules based on size or charge. The membrane, about 15 nanometers thick, is made using standard microfabrication techniques. A thin layer of amorphous silicon is sputtered on top of a silicon wafer, and after a short annealing period at about 1,400 degrees Fahrenheit the amorphous material crystallizes, becoming a porous membrane with average pore sizes of 5 to 25 nanometers. Parts of the wafer are then etched away, leaving a rigid silicon frame that holds the membrane in place. Despite the membrane’s thinness, it can withstand pressure differences of up to one atmosphere between the two sides without deforming or breaking. The researchers, who described their work in the journal Nature, say it can separate proteins from smaller molecules in just minutes, compared with hours for thicker membranes. – NYT

Marijuana does have its uses

Armed with a new study showing the drug can ease pain in some HIV patients, medical-marijuana advocates sued the US government over its claim that pot has no accepted medical uses. The lawsuit, filed in federal court on Wednesday by Americans for Safe Access, accuses the government of arbitrarily preventing “sick and dying persons from seeking to obtain medicine that could provide them needed and often lifesaving relief.” The Food and Drug Administration’s position on medical marijuana “is incorrect, dishonest and a flagrant violation of laws requiring the government to base policy on sound science,” said Joe Elford, chief counsel for Americans for Safe Access. Christina Pearson, a spokeswoman for the Department of Health and Human Services, said the agency does not comment on pending litigation. California is one of 11 US states that have made marijuana legal for people with a doctor’s recommendation. But because the US government does not recognise pot’s medical benefits, federal authorities can still arrest patients. – AP