The Havens Center is commemorating the 40th anniversary of â??Dow Dayâ? in Madison with three days of lectures and a forum. The series entitled â??The Day that Changed Madison: The â??Dow Riotâ?? forty years on,â? began Tuesday night with a lecture by Paul Buhle, a lecturer at Brown University, focusing on Madisonâ??s history of liberal activism, how it was reinvigorated in the 1960s, and its continuing effects on the university.