The first time Cecilia Ramos walked into an aikido dojo, while already happily studying tae kwon do, she just wanted to learn how to fall without injuring herself. "But after about a week and I was hooked," said Ramos, a registered nurse and chief instructor at Grass Valley Aikikai. Students of all ages and backgrounds were on the mat late Friday afternoon, working together in a give-and-take unison that looked more like a dance than hand-to-hand combat."It's blending with the opponent, matching body motions," said Ramos. "If it's a physical attack, you learn to enter into it and blend with …