A team of researchers rode a roller coaster more times than they probably care to remember, just to figure out why roller coasters trigger the passage of small kidney stones. With the further help of a 3D-printed model of a kidney filled with urine, they think they’ve solved the puzzle.
There's a lot of reasonable things I would trade for an iPad 2. 500 bucks, Pepsi, a stack of clothes, basically anything my life wouldn't miss. A 17-year-old kid from China was a little unreasonable—he traded his kidney.