Sunday, September 29, is World Heart Day.  It's a special day set aside by global health officials to draw awareness to the world's two leading causes of death, cardiovascular disease and stroke.  The President of the American Heart Association joins us today to talk about heart disease and how we can keep ourselves heart healthy.   Also…   This week, astronomers announced that they have spotted an ultra-compact dwarf galaxy some 60 light years from Earth.   A race track became a classroom for some Maryland students as they learned about science and engineering from open top Indy race cars.   The rooftop of a hotel in Thailand has been turned into an unusual farm for freshwater algae. Proponents tout the algae as a superfood.   Scientists have moved a step closer toward developing a universal vaccine against seasonal influenza.   More than a year after a locust plague was declared in Madagascar, a control program finally is about to begin.