While it seems pretty obvious that gratitude is a positive emotion, psychologists for decades rarely delved into the science of giving thanks. But in the last several years they have, learning in many experiments that it is one of humanity's most powerful emotions. It makes you happier and can change your attitude about life, like an emotional reset button.

WASHINGTON (AP) -- Being a conventional Republican has never been Newt Gingrich's style, and he clearly doesn't see it as the way to beat Mitt Romney in the presidential nominating contest.

LISBON, Portugal (AP) -- On a spring day in 1976, while hiding out in Paris, an American member of the Black Liberation Army panicked.

CAPE CANAVERAL, Fla. (AP) -- As big as a car and as well-equipped as a laboratory, NASA's newest Mars rover blows away its predecessors in size and skill.

WASHINGTON (AP) -- The supercommittee's failure reflects the nation's divide: Americans crave both the Republicans' demand for low taxes and the Democrats' insistence on protecting social programs. So far, no group or leader has persuaded them they can't have both and there's no quick solution in sight.

PHILADELPHIA (AP) -- Jerry Sandusky's brief call to a TV sportscaster may have done more to raise concern over child-sex crimes than three decades of church-abuse cases.

CHICAGO (AP) -- Rep. Jesse Jackson Jr. faces serious competition for the first time since his House career began, damaged by the last three years of allegations of corruption and embarrassing personal disclosures and made even more vulnerable by Illinois's new congressional district map.

MILLERSBURG, Ohio (AP) -- The leader of a breakaway Amish group allowed the beatings of those who disobeyed him, made some members sleep in a chicken coop and had sexual relations with married women to "cleanse them," federal authorities said as they charged him and six others with hate crime counts in hair-cutting attacks against other Amish.

PITTSBURGH (AP) -- A flood of gooey black muck dropped from a tanker truck disabled about 150 cars and damaged an unknown number of other vehicles along a nearly 40-mile stretch of the Pennsylvania Turnpike, officials said.

SEATTLE (AP) -- Eight Native Americans filed suit Tuesday against the Washington Department of Social and Health Services, claiming the agency placed them in a mission boarding school where they say they were sexually abused by a Jesuit priest decades ago.