A male Elk, with antlers in 'velvet', feeds in Yellowstone’s long summer grass. The 'velvet' that covers a growing set of antlers is actually a highly vascular skin. It supplies oxygen and nutrients to the antler's bone as it forms.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.