Date: Friday, February 22, 2013 Speaker: Boyce Griffith, Assistant Professor of Medicine and Mathematics, New York University Location: Maxwell-Dworkin G125, 33 Oxford Street, Cambridge, MA 02138 Time: Informal lunch with speaker, 12:30pm. Talk, 1:00pm. Title: Multiphysics and Multiscale Modeling of Cardiac Dynamics Abstract: The heart is a coupled electro-fluid-mechanical system. The contractions of the cardiac muscle are stimulated and coordinated by the electrophysiology of the heart; these contractions in turn affect the electrical function of the heart by altering the macroscopic conductivity of the tissue and by influencing stretch-activated transmembrane ion channels. In this talk, I will present mathematical models and adaptive numerical methods for describing cardiac mechanics, fluid dynamics, and electrophysiology, as well as applications of these models and methods to cardiac fluid-structure and electro-mechanical interaction. I will also describe novel models of cardiac electrophysiology that go beyond traditional macroscopic (tissue-scale) descriptions of cardiac electrical impulse propagation by explicitly incorporating details of the cellular microstructure into the model equations. Standard models of cardiac electrophysiology, such as the monodomain or bidomain equations, account for this cellular microstructure in only a homogenized or averaged sense, and we have demonstrated that such homogenized models yield incorrect results in certain pathophysiological parameter regimes. To obtain accurate model predictions in these parameter regimes without resorting to a fully cellular model, we have developed an adaptive multiscale model of cardiac conduction that locally deploys detailed cellular models only where needed, while employing the more efficient macroscale equations where those equations suffice. Speaker bio: Boyce Griffith is a computational scientist at New York University, where he is an Assistant Professor of Medicine and an affiliate faculty member of the Department of Mathematics at NYU's Courant Institute of Mathematical Sciences. His research focuses on the development and application of methods for simulating cardiac and cardiovascular dynamics, including the fluid dynamics of heart valves, electrical impulse propagation in cardiac muscle, and cardiac electromechanics. He is also the principal architect of the IBAMR software, a general-purpose open-source framework for simulating biological fluid-structure interaction used by a number of independent research groups around the world. Griffith received his BS in Computer Science and his BA in Mathematics and in Computational and Applied Mathematics from Rice University in 2000 and his PhD in Mathematics from the Courant Institute of Mathematical Sciences at New York University in 2005. He was a Courant Instructor in the Department of Mathematics at NYU from 2005--2006, was an American Heart Association Postdoctoral Fellow at NYU from 2008--2008, and has been a member of the faculty at NYU School of Medicine since Fall 2008. Visit http://iacs.seas.harvard.edu/events to subscribe to our Google calendar, manage your subscription to this mailing list, or access video and audio recordings of previous seminars. _______________________________________________ Iacs-events mailing list Iacs-events(a)seas.harvard.edu https://lists.seas.harvard.edu/mailman/listinfo/iacs-events

Date: Friday, March 15, 2013 Speaker: Mark Kramer, Assistant Professor of Mathematics, Boston University Location: Maxwell-Dworkin G125, 33 Oxford Street, Cambridge, MA 02138 Time: Informal lunch with speaker, 12:30pm. Talk, 1:00pm. Title: Multi-scale Seizure Dynamics Abstract: Epilepsy--recurrent, unprovoked seizures--is a common brain disease, affecting 1% of the world’s population. Seizures are typically identified as abnormal patterns in brain voltage activity. Many open questions surround epilepsy and seizures, and identifying the answers promises new insights for treatment and prevention. In this talk, I will consider brain voltage activity during seizures as observed at multiple spatial scales. I will show how techniques from mathematics and statistics can be used to characterize these data, identify common features, and connect observed brain activity to mechanisms. One specific open question is this: Why do seizures spontaneously terminate? Analysis of human brain electrical activity at various spatial scales suggests a common dynamical mechanism: a discontinuous critical transition or bifurcation. Prolonged seizures (status epilepticus) repeatedly approach, but do not cross, the critical transition. I will consider a computational model to demonstrate that alternative stable attractors, representing the seizure and post-seizure states, emulate the observed brain dynamics. These results also suggest a dynamical understanding of status epilepticus. Seizure dynamics thus provide an accessible system for studying critical transitions in nature. Speaker bio: Mark Kramer received his PhD in applied physics from the University of California, Berkeley in 2005. Following three years as a postdoctoral researcher, he was awarded a Career Award at the Scientific Interface from the Burroughs Welcome Fund. In 2009 he became an assistant professor in the Department of Mathematics and Statistics at Boston University. His research is focused on the application of ideas and techniques from mathematics and physics to problems in neuroscience, typically with clinical focus. He maintains numerous interdisciplinary collaborations with clinical, medical, and computational researchers throughout Boston and is always interested in new interdisciplinary research problems and approaches. Visit http://iacs.seas.harvard.edu/events to subscribe to our Google calendar, manage your subscription to this mailing list, or access video and audio recordings of previous seminars. _______________________________________________ Iacs-events mailing list Iacs-events(a)seas.harvard.edu https://lists.seas.harvard.edu/mailman/listinfo/iacs-events