Harvard Catalyst Profiles

My research work is focused primarily on pulmonary physiology, ranging from cellular mechanics to whole organ studies, aerosol transport mechanisms, and imaging with hyperpolarized noble gases. I have recently extended this to human studies of sleep related disorders of breathing, branching into the control of circadian rhythms. I work specifically bridging the gaps between physics, mathematics, and physiology.

At the cellular level, I work with a variety of methodologies that probe specific rheological features of the cytoskeleton, and how these are modulated and influenced by various agonists. My current work focuses on the behavior of migrating epithelial and endothelial monolayers; what controls their mechanical interactions with the microenvironment, what are the consequences to cell/cell interactions and barrier integrity, what is the physics that links motions with forces? These are important to a wide variety of diseases, including asthma and ARDS.

At the organ level, I am engaged in MRI studies of lung function using hyperpolarized noble gases, addressing fundamental questions of what can be quantified through its use in mapping local ventilation, perfusion, oxygen concentration, and airspace dimensions. With others, we have now demonstrated lung growth post pneumonectomy in an adult human, previously thought not possible. Aerosol exposure and the exposure/dose relationships, especially of ultrafine particles that do not have significant impaction or gravitational sedimentation, remain important problems in public health. We have recently proposed a new mechanism, involving irreversible kinematics and chaotic trajectories, that may explain and unify a number of experimental observations. Our theory has been confirmed in a number of initial experiments, and we are extending this work to include variations associated with growth and development from newborns to adults.

Finally, I continue to work in applied mathematics, fluid and continuum mechanics, and comparative physiology from birds to whales to, most recently, penguins and monitor lizards.

I enjoy long standing collaborations with colleagues across a variety of disciplines, which in large measure has been and continues to be an expression of the richness of cross disciplinary studies.