Song of the humpbacks

Humpback whales not only sing, they imitate the singing of other whales. And some of their tunes turn into worldwide hits, with whales all over the Pacific Ocean picking them up. Several genetically different groups of humpbacks, separate populations with little interchange among them, live in the South Pacific. Researchers recorded 11 different song types in the region from 1998 to 2008. Their study, published online in Current Biology, found that each year, songs spread from one group to another, moving east from Australia to French Polynesia. They believe that this is the first observation of a cultural change transmitted repeatedly on such a large geographic scale. Why this happens is unclear, but the lead author, Ellen C Garland, a doctoral student at the University of Queensland in Australia, said the reasons probably have to do with sex.

Only male humpbacks sing, and each group of whales sings its own tune. “If you change your song, you stand out,” she said. “We could speculate that could be more attractive to the females.” The eastward movement of the songs is another puzzle, but the scientists speculate that the larger population near eastern Australia might have greater influence. Although sounds travel only a few miles, it is possible that some individuals get close enough to be heard. This minimal contact could be enough for males from another group to pick up the new melody. The changes happen rapidly, Garland said, usually within two to three months, and the male humpbacks are enthusiastic singers.

Nicholas Bakalar
New York Times News Service

At what pace is the earth’s core moving?

Scientists found the core is moving much slower at one degree every million years rather than at one degree every year. This is the first accurate estimate of the speed of the inner core. The confirmed value can now be used to model the formation of earth’s fluid outer core and evolution of magnetic fields.

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Organic boost to solar cells

Researchers are trying to use materials with quantum dots to replace semiconductors like silicon in a solar cell. Quantum dots are tiny crystals, a few nanometers in size, and cheaper to produce than a thin-film solar cell.

Quantum-dot solar cells can also be used to absorb various wavelengths of light. But their efficiency is low, making them impractical for use.

Using a combination of materials can boost the performance of these solar cells. The researchers added an organic molecule to a quantum dot cell. They found it improved the efficiency threefold.

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