RIO DE JANEIRO >> If there were any doubts, it took less than 10 seconds - 9.81, to be exact - for Usain Bolt to erase them.He is the Olympic champion once again.On a muggy Sunday night in Rio, the Jamaican superstar won the signature event in track and field in a runaway and added this line to his already gleaming resume: first person to capture three straight 100-meter titles at the Olympics.