Wall Street Journal: Hot weather can be deadly, but a summer's full toll often isn't known until after fall has arrived. When a heat wave strikesas it has this summer in the U.S., Europe and Chinadeath rates rise. But heat's role usually isn't readily apparent. Instead, its victims die of underlying conditions, usually of the heart or lungs, that needed the extra ingredient of heat to become fatal. Moreover, those who succumb to heat often die alone and aren't discovered until after their bodies have cooled. So heat's...