About The Author

Presently, I am an Assistant Professor of Medicine at Harvard Medical School, Division of Interdisciplinary Medicine and Biotechnology, Beth Israel Deaconess Medical Center. I am also Co-Director of the Margret and H. A. Rey Institute for Nonlinear Dynamics in Medicine.

I concentrated in Physics at the University of Lisbon. In 2000, while a PhD student there, I was awarded a Fulbright grant and enrolled in the Graduate School of Arts and Sciences, Harvard University, as a special student. I completed my PhD dissertation under the supervision of Professor Eduardo Ducla Soares from the University of Lisbon, in conjunction with Dr. C.-K. Peng and Dr. Ary L. Goldberger from Harvard Medical School. My general area of research is in complex systems (nonlinear dynamics and statistical physics).

My specific focus is in biomedical applications, including improving diagnostics and monitoring of instabilities in physiologic control. The work includes the study of life-threatening cardiac diseases and also neurological pathologies related to gait disorders and seizures. This work is at the interdisciplinary crossroads of contemporary physics, bioengineering, physiology, biology and clinical medicine.

A hallmark of such complex systems is their multiscale organization, both temporally and spatially. However, the ability to model, monitor and control complex dynamics is still in its infancy and poses some of the most daunting challenges in contemporary science. My work is directed at developing (i) methods to quantify multiscale properties of complex signals, (ii) models of physiologic control that account for these properties under healthy conditions and their changes with pathology and aging, and (iii) novel indexes for risk stratification and monitoring of pharmacologic and non-pharmacologic interventions.

Over the past few years, my collaborators and I have developed quantitative algorithms to probe some of the generic features of complex systems and applied these tools to the understanding of the underlying system dynamics. We have introduced multiscale entropy and time irreversibility analysis techniques and applied them to the study of the cardiac dynamics of healthy subjects and patients with different type of pathologies. The former technique quantifies the information content of a signal across multiple time scales and the latter quantifies the degree of temporal irreversibility over multiple time scales. Time irreversibility is a fundamental property of open dissipative systems that operate far from equilibrium.

Fragmentation Of The Heartbeat: Probing The Breakdown Of Biologic Time With Aging And Disease

The trace of the human heartbeat, a dynamical signature of life itself, is regulated by an exquisitely complex “clock” called the sino-atrial (SA) node. The cells comprising this cardiac timekeeper, like those in all biologic pacemakers, are nonlinear oscillators. It is widely assumed that the SA node beats with metronomic regularity. However, even under resting