Purdue University has made several safety enhancements on its campus after the deadly shooting back in January. The university is installing emergency beacons and additional door locks in more than two dozen large classrooms. The beacons are bright yellow boxes that light up, sound an alarm and display a message during an emergency. Desktop pop-up alert windows have been added to most university-owned computers. Purdue has also integrated its emergency Twitter account with the message system and added a 24/7 emergency call center.