The Mount Sinai School of Medicine, at 100th Street and Fifth Avenue, sits on the green line. Step left when you head out the door and you are on your way down Museum Mile, past some of the ritziest addresses in New York City. It is the Manhattan of Manolo Blahniks and millionaire extravagance. Step right and in moments you are in one of the poorest neighborhoods in the city, East Harlem. It is the Manhattan of chronic health problems, littered streets and persistent poverty. It is one of those geographic divides that are so singularly striking in New York; people separated by only a few blocks live worlds apart. For new students at the medical school, educated at the best colleges and often from well-to-do families, it is no surprise that they typically step left and head toward the Manhattan they already know.