Science, January 23, 2009

Cover
Human cells infected with the protozoan parasite Toxoplasma gondii
visualized by scanning electron microscopy. In the foreground are
parasites (yellow-green) rupturing out of a dying host cell (blue); in
the background is an intact host cell containing a large
parasite-filled vacuole.
Friendship as a Health Factor
In a string of hot
articles, two social scientists report that obesity, smoking, and other
behaviors "spread" in networks. As the two friends expand their theory,
doubters sharpen their questions.
With Isolation Comes Ill Health
Social isolation, the
flip side of social networks, is believed to have dire consequences,
increasing the risk of certain diseases and earlier death. But attempts
to transform this knowledge into action have had discouraging results.
Fall Meeting of the American Geophysical Union
Galloping glaciers of Greenland have reined themselves in.
Tang hints of a watery interior for Enceladus.
The many dangers of greenhouse acid.
Snapshots from the meeting.
Earth's Degassing: A Missing Ethane and Propane Source
Natural gas seepage contributes far more methane, ethane, and propane to the atmosphere than formerly realized.

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