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It would be hard not to be optimistic after last week's progress on arms control. But the next step will require some much more fundamental changes in thinking.
Conflicting observations of the gravitational-like interactions which have engendered talk about the fifth force might have been reconciled if it were not for another set of data.
A group of independent epidemiological studies shows that fetal exposure to levels of lead previously considered safe is linked to impairment of infant mental development.