Feb
09
Teaser:

I will try to explain, in elementary terms, the deep connection between space-time geometry and quantum entropy, uncovered in the work of Bekenstein, Hawking, 't Hooft, Gibbons Jacobson, Fischler, Susskind and Bousso. This leads to the conclusion that many of the fundamental degrees of freedom, which describe our world, are inaccessible to direct local measurement. Indeed, local excitations are constrained low entropy states of the fundamental degrees of freedom. These insights give us clues to the nature of a fundamental theory of quantum gravity, and have implications for early universe...

Feb
05
Teaser:

Cold atoms and ions provide an interesting playground for a variety of measurements of fundamental physics.  Using RF traps, experiments become possible with both large ensembles of ions, e.g. in cold chemistry, and few/single ions, such as in quantum computations/simulations or optical clocks, where ultimate quantum control is required.  In the first part of the talk, recent results from our work on cold chemistry and cold molecular ions using a hybrid atom--ion experiment will be...

Jan
29
Teaser:

The dawn of gravitational wave astronomy is upon us as Advanced LIGO and Advanced Virgo begin to come on line later this year. With the first detection of gravitational waves, the cosmic cacophony of the gravitational universe will be open to us, allowing us to probe some of the densest regions in the universe as well as some of the most energetic astronomical phenomena (eg. gamma-ray bursts). In order to perform gravitational wave astronomy, one must decipher the astrophysical information encoded in the detected gravitational wave signals. This seminar will give a brief overview of the...

Jan
27
Teaser:

Microbial ecosystems in the top decimeters of sediment play an important role in determining the chemistry of the atmosphere and help support multicellular life. The metabolic rates of these microbes are strongly limited by the time it takes nutrients to diffuse from the surface. Here we combine experiments, mathematical models, and field work to understand how two microbes, the bacteria Thiovulum majus and the eukaryote Uronemella, respond collectively to overcome diffusion limitation. These microbes have independently evolved the ability attach to surfaces by means of a mucus tether. Once...

Jan
15
Teaser:

Our method of nanoscale magnetic sensing and imaging makes use of nitrogen-vacancy (NV) color centers a few nanometers below the surface of a diamond crystal. Using individual NV centers, we perform NMR experiments on single protein molecules, labeled with ^{13}C and ^2H isotopes. In order to achieve single nuclear-spin sensitivity, we...

Dec
11
Teaser:

Galaxy clusters are the most massive virialized objects in the universe, and have the potential to be highly accurate probes of cosmological parameters. A fundamental challenge for cluster cosmology is to estimate the masses of these objects using observational proxies such as X-ray luminosity and temperature, which are complicated by the merger history of clusters and the microphysical properties of the intracluster medium. These effects, while frustrating to cosmologists, provide a rich laboratory for exploring the plasma physical processes that are occurring in these massive objects. In this talk I will...

Dec
05
Teaser:

Take a break from studying and come listen to Prof. Yoshida describe the history of the universe over 13 billion years since the Big Bang. He will use the visual results from recent state-of-the-art computer simulations that aid our understanding on how astronomical objects such as stars, galaxies, and black holes form in an expanding universe. He will explore prospects for future high-performance computing using exascale computers.

Dec
03
Teaser:

Human and animal societies are exemplars of complex adaptive systems. Through multiple interactions between society members, they dynamically organize themselves and integrate information over multiple scales, both above (environmental) and below (genetic, physiological) the individual level. In the past 25 years, researchers across a range of fields including statistical physics, network theory and behavioral ecology have made enormous progress in understanding the positive and negative consequences of these multi-scale, self-organizing coordination mechanisms. I will present key concepts in...

Dec
01
Teaser:

The syntax of theoretical physics and modern finance is deceptively similar, but the semantics is very different. I present a short introduction to the principles of modern finance, and compare and contrast the field to physics.

Nov
25
Teaser:

The Ebola epidemic in West Africa has spurred an international response. This response has been strongly influenced by epidemiological models that predicted a devastating rise in cases without large-scale changes in behavior and intervention. In this talk, I introduce the mathematical principles underlying predictions of the rate and scope of a disease epidemic. I then explain how such principles have been applied to forecasting Ebola virus disease (EVD) dynamics and identifying the type and scale of necessary control. One control mechanism involves influencing behavior and social norms to limit post-death transmission, e.g., during burial ceremonies of...

Nov
24
Teaser:

The cell can be thought of as an organized collection of molecular machines. As such, many biomolecules can have moving parts, generate, bear and leverage forces, and convert chemical energy to mechanical work and vice versa. In this talk I will use several examples to illustrate how mechanics can regulate biology at the molecular scale.

 

Nov
19
Teaser:

Gelation and vitrification are the most common mechanisms for a liquid-to-solid transition in amorphous materials. For both, a heterogeneous, percolating internal structure grows and reduces the mobility of internal constituents. Macroscopic rheological properties are strongly affected but appear to be very similar for gelation and vitrification. Here we propose a novel rheological test to distinguish between gelation and vitrification. The test is based on Boltzmann’s equation of linear viscoelasticity and focuses on the distribution of relaxation modes in samples near the liquid-to-...

Nov
18
Teaser:

Great voyages of exploration have always been driven in large part by an insatiable curiosity to know what is beyond the furthest horizon you can see. Five hundred years ago, the European exploration of the globe was a central feature of the expanding scientific and artistic explosion we call the Renaissance and Enlightenment. Today, we are once again witnessing an age of exploration and discovery, as we push beyond the shores of Earth, looking deep into the far reaches of space. You and I live in an age where, for the first time in...

Nov
18
Teaser:

Entangled polymers have been thoroughly studied since the 1940s at least....or so we thought. In the last decade particle velocimetry and other imaging methods, combined with rheology, have shown that some dramatic instabilities can occur in strongly sheared well-entangled polymer melts. I will discuss how some of these new observations (such as various shear banding phenomena and `fracture') can be understood in terms of the 'Standard Model' for entangled polymers, and highlight some of the current controversies in the area.

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