We obtain a new bound on the number of two-rich points spanned by an arrangement of low degree algebraic curves in R. Specifically, we show that an arrangement of n algebraic curves determines at most Cǫn 4/3+3ǫ two-rich points, provided at most n curves lie in any low degree hypersurface and at most n curves lie in any low degree surface. This result follows from a structure theorem about arra...

A challenging problem in security is the screening of cargo. The greater size, density, and complexity of cargo makes CT-based sensing especially diffi cult. These problems are compounded when sensing geometry is limited. In this project, we aim to develop accurate physics-based models of X-ray cargo sensing and corresponding model-based image reconstruction methods for limited angle measuremen...