A tiny airconditioner that fits into a toddler’s backpack and weighs less than a frozen chicken is being developed to keep U.S. soldiers cool. There are also commercial applications, said Dr Ward TeGrotenhuis, chief engineer at the U.S. Department of Energy’s Pacific Northwest National Laboratory in Richland, Washington. He delivered a seminar about ‘miniaturised man-portable cooling systems’ recently at the meeting of the American Association for the Advancement of Science in Seattle.