Abstract: How large is the proton? How do we know, and why do we care? Recent, independent measurements of the size of the proton have yielded different results. Some see the observed inconsistencies as hints to “new” physics, namely physics beyond the standard model. As I shall describe in the talk, major developments in physics have frequently been triggered by the precise measurements of basic quantities. With regards to the proton size puzzle, we are still awaiting a resolution. I will describe the basic ideas behind the experiments as well as their results.

Abstract: Your cell membranes are made mostly of lipids, the class of biological macromolecule that includes fat, oil, and wax. This "lipidome" is a complex mixture of some 800 different types of lipid, which changes with your diet and with the administration of lipid synthesis drugs like statins. Altering the lipid composition of a membrane changes its biophysical properties, such as thermodynamic phase, fluidity, viscosity, and curvature stress. Changes in biophysical properties may in turn affect cellular functions like signaling, which often relies on the diffusive encounter of membrane-bound receptors. I will give an overview of the state of membrane biophysics, with a particular focus on recent experimental breakthroughs which admit measurements of lipid diffusion with unprecedented spatiotemporal precision. I will then discuss our own efforts to use modeling approaches in collaboration with experimental colleagues to rationalize lipid and protein spatiotemporal organization in model membranes, and our plans to extend these approaches to interpret recent measurements on live cell membranes.

Abstract: We are studying the motion of bacteria in a hyperbolic flow in a microfluidic cross channel. Our experiments test a theory which predicts that the swimming bacteria will be impeded by one-way, invisible barriers. This research is based on the idea that smooth swimming bacteria behave like a propagating chemical reaction front.

Abstract: The goal of our experiments is to find evidence of possible barriers that impede the movement of a reaction front in a three-dimensional fluid flow. The flow used is a combination of four horizontal vortices aligned with four vertical vortices, which are created through magnetic forcing. We use the excitable Belousov-Zhabotinsky chemical reaction to produce the propagating fronts. The experiments are testing an extension of the Burning Invariant Manifold Theory, from two- to three-dimensional fluid flows.

Abstract: For 60 years, the Institute for Defense Analyses (IDA) has pursued the same basic mission: bring the best scientific, technical, and analytic talent to bear on issues critical to U.S. National security, in a research environment free of commercial or shareholder interests where objectivity and the public interest are foremost. This talk will present an overview of IDA and its Systems and Analyses Center, along with snapshots of programs related to Naval mine countermeasures, ballistic missile defense, and nuclear weapons effects.

Abstract: Those faculty in the Department of Physics & Astronomy who will be taking students for summer research will give short (5 minute) presentations of their research area. Additional information will be provided about summer research opportunities that are available beyond Bucknell and how to apply for them.