Those who have survived a devastating tornado in Joplin, Missouri, should do their utmost to live up to the example set by those who died while helping others escape the storm, President Barack Obama said Sunday at a memorial service for the victims. Obama spoke about two of the heroes from the twister, which barreled into Joplin packing 200-mph winds a week ago Sunday. The tornado swept a 13-mile path, the National Weather Service said Sunday, raising its earlier estimate of six miles. Joplin City Manager Mark Rohr told CNN the death toll was 142. State officials have released the names of 87 victims.