ENHANCING VIRTUAL ENVIRONMENT-BASED SURGICAL TEAMWORK TRAINING WITH NON-VERBAL COMMUNICATION Topics: Advanced User Interfaces; Augmented, Mixed and Virtual Environments; Collaborative Augmented, Mixed and Virtual Environments; Facial Animation; Graphics in Computer Games In Proceedings of the Fourth International Conference on Computer Graphics Theory and Applications - Volume 0VISIGRAPP, 361-366, 2009 , Lisboa, Portugal