"Lens" is the Latin word for lentil. And it is indeed true that the shape of bi-convex lenses—the familiar sort used as magnifying glasses—resembles those leguminous seeds. But that resemblance may soon be a thing of the past. For a group of engineers led by Nanfang Yu, Associate Professor of Applied Physics, has worked out how to make magnifying lenses that are flat, and thinner than a hair.
"The basic thing that makes extreme precipitation events heavier in the warmer climate is that there’s more water vapor in the air, and that’s a pretty unquestioned consequence of warming," says Adam Sobel, professor of applied physics and applied mathematics at Columbia University. "The amount of water vapor in the atmosphere increases roughly about seven percent per degree Celsius. And so, the baseline expectation is that heavy rain events get heavier at about that rate also. Some models increase them faster than that, and some slower."
A study, headed by Rei Chemke, a Columbia Engineering postdoctoral research fellow, together with climate scientist Prof. Lorenzo Polvani, addresses a major discrepancy between climate models and reanalyses regarding potential strengthening or weakening of the Hadley circulation in the Northern Hemisphere as a consequence of anthropogenic emissions.
Dr. Amir Sagiv has joined the Applied Mathematics faculty. A main facet of his research is the study of random dynamics and time-reversal breaking in nonlinear optics. This work combines elements of both mathematical analysis and physical modelling, as well as extensive use of numerical simulations. The study and development of such simulations, and specifically numerical analysis of uncertainty-quantification (UQ) problems, is in itself a fascinating field in which computation, statistics, approximation, and transport theory all play a roll.