Physicists have shown that tumbled strings will form surprisingly complex knots, helping explain how knots spontaneously form in nature. (p. 398)

Little progress has been made this decade in reducing the size of the Gulf of Mexico's dead zone, a massive area of oxygen-depleted water caused by agricultural and urban runoff. (p. 395)

The Earth's magnetic poles wander around quite a bit, a phenomenon that occasionally confounded ancient explorers but is proving useful for today's archaeologists. (p. 392)

In their quest to cure type 1 diabetes, scientists are finding that turning stem cells into insulin-producing beta cells is a lot harder than it first appeared. (p. 378)

Prairie restoration is attracting interest, but because so little long-term monitoring and comparative studies have been done, researchers are still wondering whether it's really possible to re-create a prairie. (p. 376)

A new industry program to self-regulate most salad producers is forcing affected farmers to choose between adopting measures unfriendly to wildlife and a loss of major markets for their greens. (p. 362)

Physicists are exploring the use of muons generated by cosmic rays to explore Mayan archaeological sites and to probe the interiors of volcanoes and shipping containers. (p. 360)

Scientists are refining carbon dating techniques to make the archaeological timeline more precise. (p. 344)

The plight of polar bears may get most of the attention as climate change disrupts the Arctic ice, but plenty of other species, from walrus and seals to one-celled specks, are also going to see their world change radically. (p. 346)