Algorithm identifies dolphin whistles

A computer algorithm used to identify songs can also identify the signature whistles of bottlenose dolphins, a new study reports.

In the past, researchers charted these whistles on a spectrograph, an instrument that maps sound waves visually. But the algorithm is much faster and at times more accurate, said Arik Kershenbaum, a postdoctoral fellow at the National Institute for Mathematical and Biological Synthesis in Knoxville, Tenn., and the lead author of the study, which appears in the journal PLOS One.

Just as humans sound slightly different each time they sing a given song, a dolphin’s whistles vary. In a spectrograph analysis, these variations can cause confusion.

“Sometimes the dolphin sings a little longer, sometimes a little higher,” Kershenbaum said. “And there’s all sorts of acoustic variation underwater.”

So the researchers used Parsons code, an algorithm developed in 1975 to retrieve songs from a music directory. The algorithm does not look at the precise variation of frequency but considers whether the pitch goes up or down or stays the same at each point in time. They analyzed 400 whistles made by 20 dolphins.

Exactly how the animals recognize one another’s whistles and how they use the information is unclear.

– New York Times

Gold found growing on trees in Australia

It turns out gold can grow on trees, given the right conditions. A team of Australian scientists has found small amounts of gold in the leaves, twigs and bark of eucalyptus trees growing above gold deposits buried deep beneath the ground.

Unfortunately, you won’t get rich off these golden trees. The amount of gold detected was very tiny – just 80 parts per billion in the leaves, 44 parts per billion in the twigs and just 4 parts per billion in the bark. You certainly could not see any gold with the naked eye.

Still, as the scientists write in the journal Nature Communications, their study represents the first time, to their knowledge, that naturally occurring gold particles were imaged in the cells of biological tissue.

Gold is toxic to plants, which may explain why the eucalyptus trees moved much of the gold they absorbed from the ground to their leaves, says lead author Melvyn Lintern of CSIRO, Australia’s national science agency.

By shunting the gold to their leaves, the trees can easily shed the gold deposits. Then the leaves decompose, dropping gold into the soil, and the process begins again.

– Los Angeles Times