Dynamics of Complex Systems

Our research is focused on emergent dynamical properties of Complex Systems at the convergence of physics, materials science, and biology.

A special focus is on applications to cancer biology. Complex systems, i.e. systems with many dynamically interacting units, often display emergent behavior that cannot be anticipated from studies of individual units. Some examples of generic characteristics that are unique to complex systems are spiral patterns, dynamical phase transitions, and spatio-temporal chaos. Our research is focused on complex systems in materials science and biology.

Granular Dynamics: In applications to materials science, we investigate the motion of granular materials, such as sand, by developing an innovative technique to imaging the interior of a granular material, and applying network theory approaches in novel ways. Our goal is to characterize how interactions between particles in granular flows can lead to strikingly robust collective behavior such as memory of prior excitation, and segregation of particles by size. We developed a novel 3D laser scanning tomography approach that allows for direct imaging of the inside of granular flows. This is allowing us to directly observe individual and collective behavior of particles in flows. Our current analysis in collaboration with the Girvan group (UMD) focuses is on the use of network theory to assess the breaking and reforming of contact networks in granular flows. Funded by NSF.

Biodynamics: At the convergence with biology, my group is motivated both by the desire to gain fundamental insights into the behavior of living systems and by the drive to contribute to the pressing challenges associated with the explosion of quantitative information in medical research. Our analysis of shape dynamics of migrating cells has led us to discover mechanical waves as a ubiquitous underlying motor in many fast-migrating cells. Our recent work indicates that the motor for fast migrating cells is based on reaction-diffusion waves start at the leading edge and propagate down alternating sides of the cell. Our goal is to elucidate how surface chemistry and topography affects this migratory machinery, and how internal waves may be harnessed to control cell behavior. To control surface topography we use nanofabrication approaches pioneered by our collaborator J. Fourkas (Chemistry). We also develop new tools to control the arrangement and dynamics of cell groups via holographic laser tweezers (in collaboration with SK Gupta, UMD). Funded by NIGMS, NSF and NIST.

Cancer Dynamics: In a project funded by a DOD Era of Hope Scholar Award to Dr Stuart Martin, we investigate the mechanical properties of models of circulating tumor cells. We also apply Complex Systems approaches to investigate cancer related biological processes as part of a Cancer Technology interaction between the University of Maryland and the National Cancer Institute that was formalized in 2010. Work supported by DOD and NIH.


Xiaoyu Sun defended her PhD thesis on May 7, 2015. Congratulations Dr. Sun!

Thank you to Deborah Hemingway for updating our group photo (April 29, 2015)!

Joshua Parker defended his PhD thesis on April 13, 2015. Congratulations Dr. Parker!

Matt Harrington defended his PhD thesis on April 9, 2015. Congratulations Dr. Harrington!

Read More News

Recent Publications

Read More

University of Maryland


Please contact rmlee @ umd.edu for updates to this page and wlosert @ umd.edu for questions about the Dynamics of Complex Systems lab.
Thank you to Deborah Hemingway for taking our group photo!