Gabrielle Tomasello holds and wears medals at her Cameron Park home Thursday in a display of her Special Olympics awards. She competes year-round in basketball, golf, bocce, aquatics and softball and will participate in Northern California's Summer Games for the third year in a row in track events. Opening ceremonies will be held tonight, with events Saturday and Sunday.Standing at 4 feet, 9 inches and weighing 62 pounds, Gabrielle Tomasello does not give the impression that she is one gutsy jock. Yet the 12-year-old will compete in the 100-meter run, the 4x100-meter relay, the running long jump and turbo javelin at the Special Olympics Summer Games, which open with a celebration today at UC Davis. And Gabrielle can count on one thing while competing: Her sister Arianna, her brother Giovanni, mom Lisa and dad Brian will be cheering her on from the stands. Sure, Gabrielle encounters challenges because of her Down syndrome, and her family is there to help her cope.