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20 August 2011 | NewScientist | 17 Artificial sphincter in the pipeline ANOTHER milestone for custom- crafted transplants: the first lab- built sphincters. The development offers hope to people who are incontinent because of damage to their anal sphincter. The spare-part sphincters were partly made with human cells, but have been implanted only in mice so far. Khalil Bitar of Wake Forest Baptist Medical Center in Winston Salem, North Carolina, made them by growing donated smooth muscle cells from human sphincters alongside nerve cells from mice, in circular moulds. By testing the replacement sphincter with electric shocks and chemicals, Bitar’s team made sure that it contracts and relaxes as a normal sphincter does. More importantly, it survived and grew when implanted beneath the skin in the upper back of mice. “It gets its own supply of blood vessels, and the nerves connect with the mouse’s own nervous system,” says Bitar (Gastroenterology, DOI: 10.1053/j.gastro.2011.03.056). Bitar will have to demonstrate that the synthetic sphincters can function effectively when implanted in place of mice’s existing anal sphincters before beginning trials in humans. Wanted: black hole-pulsar pairs to test for extra dimensions MAKING a black hole let go of anything is a tall order. But their grip may slowly weaken if the universe has extra dimensions, something that pulsars could help us to test. String theory, which attempts to unify all the known forces, calls for extra spatial dimensions beyond the three we experience. Testing the theory has proved difficult, however. Now John Simonetti of Virginia Tech in Blacksburg and colleagues say black holes orbited by neutron stars called pulsars could do just that – if cosmic surveys can locate such pairings. “The universe contains ‘experimental’ setups we cannot produce on Earth,” he says. Black holes are predicted to fritter away their mass over time by emitting particles, a phenomenon called Hawking radiation. Without extra dimensions, this process is predicted to be agonisingly slow for run-of-the-mill black holes weighing a few times as much as the sun, making it impossible to measure. Extra dimensions would give THINK less sea monster, more doting parent: plesiosaurs gave birth to live young, probably cared for their offspring and may even have lived in large social groups, like whales. Plesiosaurs were reptiles, which tend to lay eggs. Other prehistoric marine reptiles gave birth to live young, but fossil evidence of pregnant plesiosaurs had been frustratingly elusive – until now. When F. Robin O’Keefe of Marshall University in Huntington, West Virginia, was asked to help clean up a fossil that had sat in the basement of the Natural History Museum of Los Angeles County since 1987, he found that it was an adult female carrying a single, large fetus (Science, DOI: 10.1126/science.1205689). Animals that have one large baby, such as whales, tend to shower them with care, and commonly live in large social groups based around extended families. O’Keefe speculates that plesiosaurs may have done the same. Social animals tend to be smarter than solitary ones, so plesiosaurs should show signs of intelligence. “The problem is, they’re really stupid,” O’Keefe says: their skulls were small, without much room for brains. Plesiosaurs were caring parents NATURAL HISTORY MUSEUM OF LOS ANGELES the particles more ways to escape, speeding up the process. This rapid weight loss would loosen a black hole’s gravitational grip on any orbiting objects, causing them to spiral outwards by a few metres per year, the team calculates (The Astrophysical Journal, DOI: 10.1088/2041- 8205/737/2/l28). A pulsar orbiting a black hole could reveal this distancing. That’s because the lighthouse-like pulses of radiation they emit would vary slightly depending on the size of the star’s orbit. Foamy wakes are cool, ships are not THEY are the nautical equivalent of contrails. But the foamy wakes that ships leave behind, unlike the condensation generated by aircraft, may reduce global temperatures by reflecting sunlight. It’s no reason for shipping magnates to get too excited, though: the cooling barely makes a dent in the warming effect of the massive carbon emissions attributed to shipping. As vessels traverse the oceans, they create temporary trails of white foamy water. Using a plane carrying equipment to monitor solar radiation, Charles Gatebe and colleagues at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, measured the reflectivity of the wake of four ships over several kilometres. They found that the white froth reflected more than twice as much sunlight as dark, undisturbed waters. The team used previous studies to estimate that more than 32,000 ships of 100,000 tonnes or more criss-cross the oceans at any time. Combined with their reflectivity measurements, they calculated that ships decrease the amount of solar energy absorbed by the oceans by 0.14 milliwatts per square metre (Geophysical Research Letters, DOI: 10.1029/2011GL048819). Gatebe describes the cooling effect as “a drop in the ocean” compared with the amount of warming shipping emissions cause. JASON HAWKES/GETTY For new stories every day, visit newscientist.com/news
