 ABOUT 36 MILLION PEOPLE, A TENTH OF THE COUNTRY'S POPULATION, WILL BE IN THE GRIP OF EXTREME HEAT THIS WEEK. AMERICANS ON BOTH COASTS WILL BE SCRAMBLING TO FIND WAYS TO STAY COOL. CBS'S DAVID SCHECTER SHOWS US A SIMPLE COOLING TECHNIQUE USED BY THE U.S. MILITARY THAT CAN LITERALLY SAVE LIVES.