Tag: Proceedings of the National Academy of Sciences

Local Fishermen Help Scientists Understand the Secrets of a Lake

By Veronique Greenwood | April 10, 2012 12:40 pm

lake como
Lake Como, in Northern Italy

Sometimes, the collective knowledge of generations of locals is just as valuable as a network of high-tech sensors. That’s what scientists studying the fluid dynamics of Lake Como in the Italian Alps found, when they began to interview fishermen.

The team from the University of Western Australia had been studying the complex currents and temperature gradations in the Y-shaped lake for some time, using a system of floating sensors. Alongside them were the approximately 30 local fisherman who go out each night to string out their giant gill nets, as much as 2,300 feet long and 27 feet high. In the morning, the fishermen retrieve the nets and any fish—mostly shad and whitefish—that have swum into them overnight. Read More

CATEGORIZED UNDER: Environment, Top Posts

Audio: Ancient Katydid Sings From Beyond the Grave

By Veronique Greenwood | February 7, 2012 12:46 pm

spacing is important
Above, the fossilized teeth running along the katydid’s left and right wings
that researchers used to reconstruct the creature’s call.

Well-preserved fossils can tell paleontologists myriad things, such as what color feathers dinosaurs had, how ancient spiders evolved, and what kind of microbes were around 3 billion years ago. The latest such revelation is rather whimsical, as well as being scientifically interesting. Scientists have been able to reconstruct the chirping of a Jurassic ancestor of modern katydids by examining the wings of an exquisitely preserved fossil specimen.

Katydids create their song by scraping one wing across the other, running a hard ridge of tiny teeth, like those on a comb, across the ridge on the opposite wing. The research team examined the size and shape of the teeth on the wings of Archaboilus musicus, as the Jurassic specimen is called, to come up with an estimate of the frequency of the sound that such scraping would have produced. They found that the resulting chirping would have fallen at 6.4 kilohertz, within the range of normal human hearing.

So, if you ever get the chance to travel back 165 million years, keep your ears pricked. You might hear something that sounds like this:

Image and video courtesy of Gu et al, PNAS

CATEGORIZED UNDER: Living World

Captive Cheese Fungus Gobbles Up Spills, Forming a Living, Self-Cleaning Surface

By Veronique Greenwood | January 10, 2012 1:11 pm

cheese
How a living material of cheese fungi sandwiched between plastic sheets works.

The crusty rind of cheeses like Camembert provide more than texture: they are miniature fortress walls, made of fungus, that protect the cheese’s creamy insides from bacterial invasions. Now, taking inspiration from this delicious snack, chemical engineers at ETH Zurich in Switzerland have shown that such a fungus can be enclosed in porous plastic and will digest spills, with implications for creating antibacterial surfaces from living material.

The team sandwiched a layer of Penicillium roqueforti—from, you guessed it, Roquefort cheese—between a plastic base and a top sheet of plastic with nanoscale pores that allowed gas and liquids to move through, but did not allow the fungus to spread. Then, they mimicked a kitchen spill by pouring sugary broth on the surface and watched as, over the course of two weeks, the captive fungus gradually consumed the entire spill, leaving the surface clean. As shown in the figure above, the fungi can go dormant when there is no food around, so if one had a countertop of such a material, you wouldn’t need to keep spilling sugar on it to keep the fungi happy.  Read More

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