Events

## SMARTech Video Archive

Apr

05

Bulk Topological Insulators are a new phase of electronic matter which realizes a non-quantum-Hall-like topological state in the bulk matter and unlike the quantum Hall liquids can be turned into superconductors. In this Lecture, I will first review the basic theory of topological matter and...

Apr

03

The workshop will provide a general introduction into numerical relativity and in code development within large collaborations. The number of addendees are limited, and while registration is free, it is required. In order to register, write an email to workshop@einsteintoolkit.org.

Apr

03

I describe a unified approach to locating key material transport barriers in unsteady flows induced by two-dimensional, non-autonomous dynamical systems. Seeking transport barriers as minimally stretching material lines, one obtains that such barriers must be shadowed by minimal geodesics under the metric induced by the Cauchy-Green strain tensor field associated with the flow map. As a result, snapshots of transport barriers can be explicitly computed as trajectories of ordinary differential equations. Using this approach, hyperbolic barriers (generalized stable and unstable manifolds), elliptic barriers (generalized KAM curves) and parabolic barriers (...

Apr

02

A neutrino detector, capable of detecting the neutrinos from the Sun’s fusion cycle, was strongly requested by the Theorists working on the Solar Model in the early 1960’s. The Cl^{37} → Ar^{37} detector scheme used by Davis and Harmer at the Savannah River Experiment in the 1950’s was suggested as the basis for a scaled up Solar Neutrino Detector. The details of the design and engineering of this scale up from “Laboratory” to “Production” one mile underground at the Homestake Gold Mine in...

Mar

29

Topological insulators, a novel kind of three-dimensional insulators can have a bulk insulating gap but non-trivial topological surface states. The surface states of these topological insulators show Dirac-like behavior with the spin polarization locked perpendicular to the electron momentum by the effect of strong spin-orbit interaction. As the locking protects the surface electrons from back scattering, they are predicted to have high mobilities. The surface state of Bi_{2}Se_{3} and Bi_{2}Te_{3} topological insulators has been observed by angle-resolved...

Mar

27

When a fast moving drop collides with a layer of fluid it a produces a splash, a spray of secondary droplets. There is a bewildering variety of splash morphologies and droplet distributions which manifest as the system parameters (droplet size and speed, layer depth, fluid properties) are varied. Despite this complexity, a splash begins with the formation of a sheet-like jet. There are at least two varieties of jets: the large and slow lamella jet and the small and quick ejecta jet. In this talk I will present our progress towards understanding the simplest of splashes, the so-called crown splash, which results from the disintegration...

Mar

26

The homotopy theory of topological defects in ordered media fails to completely characterize systems with broken translational symmetry. We argue that the problem can be understood in terms of the lack of rotational Goldstone modes in such systems and provide an alternate approach that correctly accounts for the interaction between translations and rotations. Dislocations are associated, as usual, with branch points in a phase field, whereas disclinations arise as critical points and singularities in the phase field. We introduce a three-dimensional model for two-dimensional smectics that clarifies the topology of disclinations and geometrically captures...

Mar

26

With recent advances in experimental imaging, computational methods, and dynamics insights it is now possible to start charting out the terra incognita explored by turbulence in strongly nonlinear classical field theories, such as fluid flows. In presence of continuous symmetries these solutions sweep out 2- and higher-dimensional manifolds (group orbits) of physically equivalent states, interconnected by a web of still higher-dimensional stable/unstable manifolds, all embedded in the PDE infinite-dimensional state spaces. In order to chart such invariant manifolds, one must first quotient the symmetries, i.e. replace the dynamics on M by an equivalent, symmetry reduced flow on M/G, in...

Mar

22

Gamma-Ray Bursts (GRBs) are the brightest light sources in the Universe, as well as the most distant sources known. These characteristics, combined with their powerlaw spectra, make them ideal cosmological probes. In this talk I will discuss how GRBs are impacting several areas of extragalactic astrophysics and cosmology. In particular, I will show how they can be used to trace the evolution of the mean density and clumpiness of the interstellar medium with redshift, and the properties of dust in high-z galaxies. Detection of GRBs at very high redshifts can help set constraints on the small-scale power spectrum of density fluctuations. High-resolution observations of long GRBs...

Mar

19

In the natural world, complex behaviors such as learning, aggression and sleep are regulated by interconnected networks of genes and their products. Owing to their nontrivial topology and large number of components, most of these networks are poorly understood and consequently, our knowledge of how diverse behaviors arise remains limited. In this talk, I will argue that the fruit fly circadian clock, a genetic circuit that signals to and modulates several key behavioral networks, is an ideal system with which to dissect the fundamental principles that govern organismal...

Mar

15

Most of the baryons in the present universe are missing. This talk gives a historical review of the issue, followed by some highlights of current theoretical and observational effort to understand it.

Mar

14

Engineered biological circuits expressed in living cells are becoming increasingly attractive as a technology, with applications...

Mar

13

This talk will describe new results on the properties of colloidal crystals, both on their solidification and on their melting. It will describe how hard-sphere like colloids crystallize, and will explore the huge discrepancy between the nucleation rates predicted by theory and measured in simulation and those measured experimentally. The discrepancy can be as large as 150 orders of magnitude! A simple modification to the theory, suggested by experiment, is able to account for this behavior and to rectify the discrepancy....