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摘要

A long rest for the sun The sun may sit out the next solar cycle, and even go into a prolonged lull lasting several decades, say solar scientists. Such a "grand minimum" would slightly cool the Earth, but the effect would be far too small to offset global warming.Treatment in sight Two people in the US with progressive degeneration of the retina are to become the first recipients of a pioneering treatment derived from human embryonic stem cells. Doctors will inject their eyes with retinal pigment cells that Advanced Cell Technology of Worcester, Massachusetts, grew from the stem cells.