Mark McClusky says for elite athletes today, pushing boundaries and breaking records is all about "the aggregation of marginal gains."
Japan is bracing for a third possible explosion at its troubled Fukushima Dai-ichi nuclear power plant. Two hydrogen explosions have already rocked the plant, injuring several workers. Water levels dropped severely at another reactor, completely exposing the fuel rods and raising the threat of a meltdown, which happens when the fuel pellets get so hot, they burn through the containment structures.
We speak with Paddy Regan, a nuclear physicist at the University of Surrey in the U.K.