I should mention that Yen is a PhD student in Biomedical Engineering and Serge is an M. D. /PhD student who's getting his PhD in Biomedical Engineering.

我要说的是,叶是生物医学工程的博士生,斯吉是医学和生物医学工程的双学位博士,他博士的研究方向是生物医学工程

耶鲁公开课 - 生物医学工程探索课程节选

Now when he said it, he was a medical doctor at Oxford University.

说这话时，他是牛津大学的医学博士。

哈佛公开课 - 幸福课课程节选