ScienceDaily: When Ohio State glaciologists failed to find the expected radioactive signals in the latest core they drilled from a Himalayan ice field, they knew it meant trouble for their research. But those missing markers of radiation, remnants from atomic bomb tests a half-century ago, foretell much greater threat to the half-billion or more people living downstream of that vast mountain range. It may mean that future water supplies could fall far short of what’s needed to keep that …