NEW ORLEANS – Robert Green guesses it was about 5 a.m. when the water first broke through. By 5:10, he, his mother, brother, cousin, and three grandchildren, ages 4, 3, and 2, were on the roof. Within five minutes, their house was floating down the street. By 5:20, the home, pinned against an oak tree, was crumbling under the water pressure. The next 10 minutes were a blur, but sometime within them, his 3-year-old granddaughter Shanai “Nai Nai” Green was swept away by the current.