Sharks ‘Scales” Create Tiny Whirl Pools for Speed

by Charles Q. Choi

Razor-sharp scales on their skin seem to make it easier for sharks to race through the water, by generating whirlpools that help pull them along, researchers say. This research eventually could lead to an artificial shark skin that enhances the swimming of underwater robots, the researchers add.

Harvard University bioroboticist George Lauder and graduate student Johannes Oeffner created a simple robot and placed real shark skin around it to study the skin’s properties.

They discovered that the toothlike scales, called denticles, generated vortexes on the front edge of the skin, eddies that essentially would help suck the shark forward. “Leading-edge vortices are well-known in insect and bird flight,” Lauder said…

(read more: Live Science)     (image: George Lauder, Johannes Oeffner)

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Northern forests may be losing their ability to trap carbon

by Joel N. Shurkin

The northern forests of western Canada are likely absorbing less carbon dioxide because of climate change, and the decline may be making a bad situation worse, researchers from Quebec and China have concluded. If the situation remains as it is, the forests may actually put more carbon dioxide back into the air than they absorb, the researchers said. While researchers have seen this happen in tropical rainforests, the new result suggests that this problem could be much more widespread.

The scientists at the University of Quebec’s Montreal campus and from several Chinese institutions, reporting in this week’s Proceedings of the National Academy of Sciences, have been able to put numbers to the fears that the ability of northern forests to absorb carbon — to act as carbon sinks — was decreasing.

The researchers studied 96 permanent old-growth forests out of 20,000 candidates, concentrating on aspens, which are more sensitive to changes in precipitation. They deliberately chose forests that were not affected by insect infestation or fires. They then estimated biomass production — the growth of the trees — from 1968 to 2008…

(read more: PhysOrg)     (image: Linnea Hanson/U.S. Forest Service)

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