From Learner to Provider: Navigating Role Tensions in Postgraduate Medical Training Through Activity Theory. - Kwong, Sin-Yee Patty; Yu, Shiuan-Ruey; Liao, Kuo-Chen; Liao, Shu-Chen; Hsiao, Cheng-Ting; Chaou, Chung-Hsien (Perspectives on Medical Education, 2025)