I'm eager to formulate a framework for my PHD dissertation, which is aimed to establish a motivating system and its working mechanism for professional deveopment of university teachers at different career stages but I find the relevant literaature both at home and abroad is scant. I awfully need to know what motivates individual university teacher at various career to move towards professional development. What determines the varying path for different teachers even in a similar academic condition? What is the standard definition for professional development of university teachers? How to evaluate it since it is dynamic , personlized and culture-specific? how to coordinate the external factors and the internal ones to drive it proceed all the time? THANKS!