Physics and Astronomy

"Group-theory constraints on color-ordered amplitudes in non-abelian gauge theories" by Alexander Edison
"Localization of an OFDI tethered capsule for unsedated gastrointestinal 3D imaging" by Melissa Haskell
"Computational Modeling of Phonons at Crystal Interfaces: An Application to the Cryogenic Dark Matter Search" by William Page
"A Method for the Numerical Calculation of Surface Acoustic Waves on Piezoelectrically Active Crystals" by William Scott Perry
"Gravity Darkening and Brightening in Binary Stars" by Helen White

We explore the processes controlling the global mean energy balance of the Earth and the poleward energy transport in the climate system. The global mean planetary albedo is partitioned into a component due to atmospheric reflection (clouds) and a component due to surface reflection. In the global mean, the vast majority (88%) of the planetary albedo is due to atmospheric processes. The surface makes a substantially smaller contribution to the planetary albedo because atmospheric absorption and reflection of incident radiation attenuate the surface's contribution to planetary albedo by a factor of three. In global climate models, the absorbed shortwave radiation differs by 10 W m-2 due to differences in cloud reflection.

The poleward energy transport in the climate system also differs by approximately 20% in global climate models. We partition the poleward energy transport into components due to emitted longwave radiation, incident shortwave radiation, and the spatial structure in planetary albedo due to atmospheric and surface reflection. We find that inter-model differences in poleward energy transport are primarily a consequence of differences in cloud reflection. These results collectively suggest that the global mean energy balance and the strength of the atmospheric circulation in climate models hinge critically on their representation of clouds.
-Aaron Donohoe, Ph.D.'03,  Program in Atmospheres, Oceans and Climate at MIT.

Reception 12:00 pm to 12:30 pm in Searles 314.

"Why didn't nature make brains better at estimating probabilities?" Daniel Goroff--Vice President of the Alfred P. Sloan Foundation and former professor, dean, and government official--examines what probability, decision theory, and behavioral economics can teach us about mathematics education and life. 

BIO: Daniel L. Goroff is Vice President and Program Director at the Alfred P. Sloan Foundation, a philanthropy that makes grants supporting breakthrough science, technology, and economics. He is Professor Emeritus of Mathematics and Economics at Claremont's Harvey Mudd College, where he previously served as Vice President for Academic Affairs and Dean of the Faculty.

Goroff earned his B.A.-M.A. degree in mathematics summa cum laude at Harvard as a Borden Scholar, an M.Phil. in economics at Cambridge University as a Churchill Scholar, a Masters in mathematical finance at Boston University, and a Ph.D. in mathematics at Princeton University as a Danforth Fellow.

Daniel Goroff's first faculty appointment was at Harvard University in 1983. During over two decades there, he rose to the rank of Professor of the Practice of Mathematics while also serving as Associate Director of the Derek Bok Center for Teaching and Learning, and as a Resident Tutor at Leverett House.

A 1988 Phi Beta Kappa Teaching Prize winner, Goroff taught courses for the mathematics, physics, history of science, economics, and continuing education programs at Harvard. He was also the founding director of a Masters Degree Program in "Mathematics for Teaching" offered through the Harvard Extension School. Beginning with the international distance education courses he developed using audiographics conferencing over twenty years ago, and continuing through his most recent online course called "Decisions, Games, and Negotiations," Goroff has been an educational innovator throughout his teaching career.

In pursuing his work on nonlinear systems, chaos, and decision theory, Daniel Goroff has held visiting positions at the Institut des Hautes Etudes Scientifiques in Paris, the Mathematical Sciences Research Institute in Berkeley, Bell Laboratories in New Jersey, and the Dibner Institute at MIT.

In 1994, Goroff was elected to a three-year term on the Board of Directors of the American Association for Higher Education (AAHE). During 1996-97, he was a Division Director at the National Research Council (NRC) in Washington, and during 1997-98, Goroff worked for the President's Science Advisor at the White House Office of Science and Technology Policy (OSTP). That year he was named a "Young Leader of the Decade in Academia" by Change: The Magazine of Higher Education.

As Director of the Joint Policy Board for Mathematics (JPBM) from 1998 to 2001, Daniel Goroff was called to testify about educational and research priorities both by the House and again by the Senate during the 106th Congress. He also testified before the 109th Congress. A former Chair of the U.S. National Commission on Mathematics Instruction at the National Research Council (NRC), he was co-director of the Scientific and Engineering Workforce Project based at the National Bureau of Economic Research (NBER). Goroff was a founding board member of the nonpartisan group "Scientists and Engineers for America" and is a member of the NRC's Board on International Scientific Organizations.

With his vacation and consulting time, Daniel Goroff works on nonprofit strategies and projects through the firm Anthony Knerr & Associates. Beginning in 2009, he has taught courses as Distinguished Visiting Professor of Mathematics at Columbia University's Teachers College. During 2010, Goroff served part time as Assistant Director for Social, Behavioral, and Economic Sciences at the White House Office of Science and Technology Policy.

This talk is the Cecil T. & Marion C. Holmes Mathematics Lecture sponsored by the Mathematics Department and the Computation in the Liberal Arts Colloquium (CLAC).

Daniel Goroff, Vice President of the Alfred P. Sloan Foundation, will present a Mathematics seminar talk titled "Poincare and the Great Chaos Scandal".

Abstract:  Henri Poincare lived in France at the turn of the 20th Century and invented much of modern mathematics-including what has come to be called "chaos theory." How this happened is a story full of surprises. It starts with studying pendula, planets, and other dynamical systems whose motion seems familiar and predictable. After many mistakes and missteps, the whole idea of what it means to solve a differential equation changed.

"Chemical microscopy of nanostructured semiconductors"

Chemical Microscopy, (or chemical imaging) is a newly emerging spectroscopic characterization technique designed to probe details of structure and dynamics at the single molecule level. Because of the spatial resolution limitations in wide-field imaging, the photoluminescence images themselves don't directly convey the desired structural information; that information is actually encoded in the degrees of freedom (wavelength, polarization, correlations in time, etc.) from individual photons. I'll talk about two interesting case-studies in chemical imaging: optical probes of charge-separation in isolated hybrid quantum-dot/conjugated organic nanostructures, and crystalline supramolecular assemblies (nanowires) of a common semiconducting polymer, P3HT.

Michael Barnes, Ph.D.
University of Massachusetts - Amherst