Paul Yock is the Weiland Professor of Medicine at Stanford and the founding co-chair of the Department of Bioengineering. Dr. Yock is internationally known for his work in inventing, developing and testing new medical devices, including the Rapid Exchange (tm) balloon angioplasty and stent system, now the primary system in use worldwide, and the Doppler-guided hypodermic needle system, P-D Access (tm).   Dr. Yock also authored the fundamental patents for intravascular ultrasound (IVUS) imaging and founded Cardiovascular Imaging Systems, now a division of Boston Scientific.  Dr. Yock's research focuses on preclinical development and clinical trials of catheter devices, most recently in the area of stem cell delivery to the heart.  Dr. Yock also founded and directs the Program in Biodesign, which is a teaching and mentoring initiative focusing on the process of needs finding, invention and technology translation in the biomedical field.