Events

## SMARTech Video Archive

Feb

07

This talk is devoted to quasi-periodic Schrödinger operators beyond the Almost Mathieu, with more general potentials and interactions. The links

between the spectral properties of these operators and the dynamical properties of the associated quasi-periodic linear skew-products rule the

game. In particular, we present a Thouless formula and some consequences of Aubry duality.

Feb

03

High-energy neutrinos are thought to be emitted by astronomical objects

such as active galactic nuclei, gamma-ray bursts, and supernova

remnants. However, due to their small predicted flux and large

backgrounds from neutrinos and muons created in the atmosphere, they had

not been observed until now. The IceCube Neutrino Observatory

instruments a cubic kilometer of ice at the South Pole to detect

neutrinos mainly above 100GeV. In a high-energy (>20TeV) data set from

the first couple of years of the full detector, an excess above

atmospheric backgrounds is observed. These neutrino events are

incompatible in energy spectrum and...

Jan

31

The unification of the four fundamental forces remains one of the most important issues in theoretical particle physics. In this talk, I will first give a short introduction to Non-Commutative Spectral Geometry, a bottom-up approach that unifies the (successful) Standard Model of high energy physics with Einstein's General theory of Relativity. The model is built upon almost-commutative spaces and I will discuss the physical implications of the choice of such manifolds. I will show that even though the unification has been...

Jan

31

When the light interacts with low-dimensional systems, new optical phenomena can arise because of the reduced dimensionality. Classic examples include discrete electronic energy levels quantum dots or plasmon resonances of metallic nanoparticles. In addition to the dimensionality or shape, the light-matter interaction can be further tuned by using optical nonlinearities. Typically, the induced polarization currents depend linearly on the intensity of the radiation field. However, when the linear relationship breaks down new interesting phenomena arise like frequency conversion or intensity dependent refractive index. We combine these new possibilities with the interesting properties of...

Jan

30

Driving nanomagnets by spin-polarized currents offers exciting prospects in magnetoelectronics, but the response of the magnet to such currents

remains poorly understood. For a single domain ferromagnet, I will show that an averaged equation describing the diffusion of energy on a

graph captures the low-damping dynamics of these systems. In particular, I compute the mean times of thermally assisted magnetization reversals

in the finite temperature system, giving explicit expressions for the effective energy barriers conjectured to exist. I will then outline the problem of extending the analysis to...

Jan

27

The spectrum of cosmic rays includes the most energetic particles ever observed. The mechanism of their acceleration and their sources are, however, still mostly unknown. Observing astrophysical neutrinos can help solve this problem. Because neutrinos are produced in hadronic interactions and are neither absorbed nor deflected, they will point directly back to their source. This talk will cover searches for high-energy neutrinos (> 100 TeV) at the IceCube neutrino observatory, which have recently produced the first evidence for a flux beyond standard expectations from neutrinos generated in the Earth's atmosphere. This includes the detection of two events with energies above...

Jan

23

A new observational era in gravitational wave astronomy is poised to begin in this decade, with the upcoming start of Advanced LIGO and Advanced Virgo. These instruments will be capable of the direct detection of gravitational wave transients, which will yield new insights into the engines powering some of the most energetic astrophysical events: the coalescence of neutron star and/or black hole binary systems, core-collapse supernovae, and isolated neutron star instabilities. I will present the path towards this detection using the second generation of gravitational wave interferometers, and summarize the open analysis challenges, prospects for astrophysical inference and the...

Jan

06

Computational modeling of eukaryotic cells moving on substrates is an extraordinarily complex task: many physical processes, such as actin polymerization, action of motors, formation of adhesive contacts concomitant with both substrate deformation and recruitment of actin etc., as well as regulatory pathways are intertwined. Moreover, highly nontrivial cell responses emerge when the substrate becomes deformable and/or heterogeneous. Here we extended a computational model for motile cell fragments, based on an earlier developed phase field approach, to account for...