Seminars

The MRSEC holds seminars presenting research at the frontier of Bioinspired Soft Materials. The seminars are targeted towards grad students and other researchers in the field, although everyone is invited to attend. As the topic is highly interdisciplinary, seminars are designed to be accessible to a wide range of backgrounds. 

MRSEC Seminars Organizers:
John Berezney (Dogic/Fraden Lab Postdoc)

Thursday, March 21, 2019
Johannes Zwanikken, UMass Lowell
MRSEC Seminar: The emergence of multiple time scales in active matter: creating memory by tuning the direction of self-propulsion
Abstract: Active materials, where the components dissipate energy into directed motion, display unique phases and functional properties that are not available to their ‘passive’, thermal counterparts, which are extensively used in nature and hold great promise for the design of new functional materials with unique structural and dynamic properties. However, the powerful predictive tools that have been designed for passive matter do not translate to active systems. Despite many recent contributions and advances, the connection between the microscopic properties of the components and the behavior of the ensemble is still difficult to predict.

To interrogate that connection further we study ensembles of active polygons with Newtonian dynamics,  focusing on how clustering and collective motion is affected by the direction of self-propulsion. We observe that both the structural and dynamic properties of the clusters are strongly dependent on the direction of self-propulsion, enabling a switch between effective Markovian behavior and periodic behavior with long characteristic time scales. We design a reaction network model for the dynamic evolution of the clusters in a ‘state space’, and find that the topology of this network is strongly influenced by the typical collision dynamics of the particles. Certain topologies enable loops in state space that have characteristic time scales and connect to the emergence of periodic behavior. We conclude that if a Boltzmann-type distribution could be formulated for active matter, it would need to incorporate not only the interaction potential, but also the character of the microscopic motion. Furthermore, we demonstrate that relatively simple active systems can harness a complex dynamic behavior with a hierarchy of characteristic time scales.
Abelson 229, 4PM

Thursday, March 28, 2019
Alexander Petroff, Clark University
Title: Fast-moving bacteria self-organize into active two-dimensional crystals of rotating cells
Abstract: We investigate a new form of collective dynamics displayed by Thiovulum majus, one of the fastest-swimming bacteria known. Cells spontaneously organize on a surface into a visually striking two-dimensional hexagonal lattice of rotating cells. As each constituent cell rotates its flagella, it creates a tornado like flow that pulls neighboring cells towards and around it. In the first part of the talk, we describe the earliest stage of crystallization, the attraction of two bacteria into a hydrodynamically-bound dimer. In the second part of the talk, we present the dynamics of bacterial crystals, which are composed of 5–200 hydrodynamically bound cells. As cells rotate against their neighbors, they exert forces on one another, causing the crystal to rotate and cells to reorganize. We show how these dynamics arise from hydrodynamic and steric interactions between cells. We derive the equations of motion for a crystal, show that this model explains several aspects of the observed dynamics, and discuss the stability of these active crystals.
Abelson 229, 4PM

Thursday, April 4, 2019
John Biddle, Harvard Medical School
Title: Negative Reciprocity underlies the interactions of Sox2 and Oct4 on DNA: Implications for energy expenditure in gene regulation
Abelson 229, 4PM

Thursday, April 11, 2019
Thomas Fai, Brandeis Applied Mathematics
Abelson 229, 4PM

Thursday, April 18, 2019
Rebecca Menapace and Bozhanka Vitanova, Brandeis
Title: An Introduction to the I-Corps Program for the MRSEC
The Brandeis Innovation Center will present an overview of the NSF-funded i-Corps Program and showcase how MRSEC research could have applications beyond campus. Attendees will get a sense of what it takes to connect their academic insights to industry applications and even create a new enterprise. If you've ever wondered how Bio-Inspired research could lead to innovation, this session is for you!
Abelson 229, 4PM

Thursday, May 2, 2019
Kirill Korolev, Boston University
Abelson 229, 4PM

Thursday, May 9, 2019
Renato Mirollo, Boston College
Abelson 229, 4PM

Thursday, May 23, 2019
Nathan Derr, Smith College
Abelson 229, 4PM


 See past events.