A Journey from Light Scattering to Biophysics…

Paul Saulnier
Physics Department
Gustavus Adolphus College

From light scattering: There has been much interest recently in using non-ionizing radiation (IR and visible light) to replace x-rays in many medical imaging applications. Optical heterodyning is a powerful detection scheme that allows the preferential detection of ballistic photons transmitted through a random media, enabling the imaging of absorbing structures within. The ability to image, in transmission, is found to be greatly enhanced using a reduced coherence length source. The effect on image quality of the transport mean-free-path length is quantified and found to depend on source coherence length.

To biophysics: Patterns are pervasive in the world with many examples being found in the arts, the humanities, as well as the natural and social sciences. Some spatial patterns are easily perceived, as in the symmetric structure of a snow flake, while others are more subtle (for example, the distribution of sand grains on a beach). This part of the seminar will discuss an interdisciplinary study that applies some simple ideas from statistical mechanics to describe the spatial distribution of collections of living organisms. The goal of this work is to be able to infer the behavioral characteristics of the individuals comprising the collection based solely on the spatial distribution of the aggregate population.