Faculty at 24 Ontario colleges including Cambrian and Boreal have gone on strike, affecting more than 500,000 students. The Ontario Public Services Employees Union says the two sides failed to resolve their differences by Sunday’s midnight strike deadline.  The strike involves more than 12,000 professors, instructors, counselors, and librarians. The union’s last proposal called for called for improvements in job security and for faculty to have a stronger voice in academic decision making. But the colleges said the demands would have added more than $250 million in annual costs.