Events Archive

May
01
2012
Non-conservative Optical Forces on Nanoparticles
We will address some basic questions related to the light forces on small (Rayleigh) particles, which are usually described as the sum of two terms: the dipolar or gradient force and the scattering or radiation pressure force. The scattering force is traditionally considered proportional to the Poynting vector, which gives the direction and magnitude of the momentum flow. However, as we will show, when the light field has a non- uniform spatial distribution of spin angular momentum there is an additional  non-conservative force term is proportional to the curl of the spin angular momentum of...
Apr
24
2012
Dynamics by the Dozen
Nonlinear dynamics has the feature that it is conceptually and mathematically challenging and yet ubiquitous in its applications. Indeed, one of the appeals of the subject is the universality of some of its frameworks and results. We are attempting to take advantage of such wide applicability in order to involve an unusual range of participants in nonlinear dynamics research. This range spans from postdoctoral to K-12 students as well as teachers.
Apr
23
2012
Cavity Optomechanics
Cavity optomechanics is rapidly developing into a major area of research.  This is a result of the developments from two converging perspectives on the physical world. From the top down perspective, ultra-sensitive micromechanical and nanomechanical detectors have become available utilizing the advanced materials and processing techniques of the semiconductor...
Apr
20
2012
Reduced Order Modeling and Gravitational Waves
I will give an overview of a program to map the space of configurations of binary compact coalescences, starting for preliminary indications a couple of years ago that the problem is amenable to reduced order modeling. I will then give an overview of Reduced Basis, our results obtained so far and a roadmap for the future.  Essentially, the core issue is how to chose the most relevant points in parameter space, in a nearly optimal way, and to select which configurations are "the most representative ones". This applies to the case in which the emitted gravitational waves can be simply evaluated using closed form approximations or obtained by solving simple equations but,...
Apr
19
2012
The Astrophysics of Super Massive Black Holes
Biosketch: Dr. David Ballantyne obtained his Ph.D. in 2002 from the University of Cambridge, and has been an Assistant Professor at the Center for Relativistic Astrophysics in the School of Physics since 2008.  His research concentrates on topics in high-energy astrophysics with an emphasis on interpreting existing data and making predictions for future observations. His main interests are the evolution of galaxies and their central supermassive black...
Apr
19
2012
Computing gravitational perturbations and metric reconstruction for extreme-mass-ratio inspirals on a Schwarzschild black hole using frequency domain methods
Extreme-mass-ratio binaries, composed of a small compact object (SCO) and supermassive black hole (SMBH), are eventual observational candidates for future space-based gravitational wave observatories.  Theoretically, these binaries are examples of the as-yet not thoroughly solved two-body problem in general relativity.  Extreme-mass-ratio inspiral (EMRI) calculations proceed by using black hole perturbation theory.  The gravitational field of the small mass affects its own orbit in the background geometry,...
Apr
19
2012
3D Anderson Localization of Ultracold Matter
Apr
18
2012
C21U Town Hall: Udacity's Sebastian Thrun to speak on Reinventing the Universities
Sebastian Thrun recently left Stanford University and started Udacity. Udacity is an online university that seeks to reach the 99% of the world population that are presently excluded from high-quality higher education. The first class on Artificial Intelligence, jointly offered with Stanford, attracted 160,000 students, of which 23,000 graduated with Stanford-level qualifications. The speaker will discuss his experience with traditional forms of education, and brainstorm how higher education may look like in the digital age. Thrun is co-founder of Udacity, a Google VP, and a Stanford Research Professor. At Google, he runs Google X, home to the Google self-driving car...
Apr
17
2012
Entropic elasticity and structural change in biofilament networks
In this talk we will focus on the elasticity of soft filamentous networks. We will begin with the mechanical behavior of fibrin networks whichhave been shown to be highly extensible in recent experiments. We believe that the high extensibility of the networks has its origins in the force inducedstructural change in the proteins making up the fibrin fibers. We will present a model and experimental evidence in support of our hypothesis. In theremainder of the talk we will describe how the quasi-harmonic approximation of statistical mechanics can be combined with the finite element method (usedin structural analysis of buildings,...
Apr
16
2012
Cellular Mechanics: The active polymer networks underlying force transmission in living cells

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