Events Archive

Oct
24
2012
Applications of homotopy method on nonlinear partial differential equations
Homotopy method is being used to explore nonlinear partial differential equation system arising from engineering and physics. This new approach is used to compute multiple solutions of nonlinear PDEs and yields the discretized polynomial systems, which involve thousands of variables. This method can also handle the singularities. This talk will cover the recent progress on nonlinear PDEs such as free boundary problem and hyperbolic conservation law problem.
Oct
23
2012
Forcing it on: Cytoskeletal dynamics during lymphocyte activation
Activation of T lymphocytes by antigen-presenting cells involves cell spreading driven by large-scale physical rearrangements of the actin cytoskeleton and the cell membrane, and accompanied by the assembly of signaling molecules into dynamic microclusters. Several recent observations suggest that mechanical forces are important for efficient T cell activation. How forces arise from the dynamics of the cytoskeleton and the membrane during contact formation, and their effect on microcluster assembly and signaling activation is not well understood. We imaged the membrane topography, actin dynamics...
Oct
22
2012
Frontiers In Science Public Lecture: History of the Universe from the Beginning to End
The history of the universe in a nutshell, from the Big Bang to now, and on to the future – John Mather will tell the story of how we got here, how the Universe began with a Big Bang, how it could have produced an Earth where sentient beings can live, and how those beings are discovering their history.  Mather was Project Scientist for NASA’s Cosmic Background Explorer (COBE) satellite, which measured the spectrum (the color) of the heat radiation from the Big Bang, discovered hot and cold spots in that radiation, and hunted for the first objects that formed after the great explosion....
Oct
18
2012
Generating and Manipulating Quantized Vortices in Highly Oblate Bose-Einstein Condensates
Studies that involve single vortex dynamics, vortex-vortex interactions, and vortex-impurity interactions are essential in developing a deeper understanding of the nature of superfluidity and in particular, superfluid turbulence.  In highly oblate systems, vortex dynamics have a two-dimensional (2D) nature and the resulting superfluid characteristics may be substantially different from those in three-dimensional (3D) superfluids. However, there have been remarkably few experimental studies of 2D vortex dynamics in superfluids. Therefore...
Oct
17
2012
Staying dry to stay alive: The ant raft and other water-repellent systems
Oct
16
2012
Toward a predictive continuum model for dense granular flows
Oct
12
2012
Science and a Journey of Extremes
Physicist and adventurer Francis Slakey describes his decade long journey that led to his becoming the first person to both summit the highest mountain on every continent and surf every ocean.  The talk reviews some of the people he encounters and the challenges he endures – a Lama who gives him an amulet etched with “life’s meaning”, an ambush in the jungles of Indonesia, a life-or-death choice atop Everest – that culminate in a recognition that science is the most powerful tool we have to...
Oct
11
2012
GRB Studies in the GeV Band
Gamma-ray bursts (GRBs) have been shown by the Fermi LAT to be a source of gamma rays with energies as high as ~100 GeV in the rest frame. Detection at higher energies may be possible with next-generation ground-based instruments. I will present results from a new simulation of GRB detections with the upcoming Cherenkov Telescope Array (CTA), using models based on the combined observations of Fermi LAT and lower-energy satellite experiments. This simulation allows the prediction of the overall detection rate, how this rate might vary as a function of telescope performance and uncertain GRB statistical properties, and the likely properties of detected GRBs. I will also show a preliminary...
Oct
11
2012
Diatomic Molecules as Quantum Tools
Our group is applying the techniques of modern atomic physics to the system of diatomic molecules.  Molecules are more complex than atoms because of their vibrational and rotational degrees of freedom, and this makes them difficult to control.  However, we have identified a variety of simple principles that allow us to make use of these "new" properties to provide powerful types of leverage on a broad range of problems.  These span...
Oct
09
2012
Geometry-induced rigidity and functionality in thin elastic shells
I will present some recent results from our Lab on the mechanical response of complex-shaped shells subject to loading and in different mechanical environments (with or without an in-out pressure difference). A powerful aspect of our experimental approach is that the geometry and material properties of our shells can be accurately custom-controlled using digital rapid prototyping techniques. First, we focus on the linear response of non-spherical shells under indentation to explore the new concept of geometry-induced rigidity. Despite the complex geometries, we find a remarkable predictive description. Moreover, we investigate universal modes of localization...

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