Integrated Calendar

Remarkably, a generic interacting system with many degrees of freedom is often well described by a random matrix drawn from an appropriate ensemble, which solely relies on the symmetries of the system. This is one of the central premises of quantum chaos theory which explains the fascinating universality of statistical properties of eigenvalues and eigenstates of generic systems. Such systems, slightly pushed out-of-equilibrium, are
normally expected to relax diffusively. In this talk I will show that disordered and interacting systems which exhibit a many-body localization (MBL) transition, behave in a strikingly different manner than expected from the above tenets in both one dimensional [1,2] and two dimensional systems [3]. These systems thermalize subdiffusively, have a vanishing diffusion coefficient and cannot be described by usual random matrix ensembles
[4]. I will show the implications of these results on thermalization in closed quantum systems, and will derive a general relation between statistical properties of matrix elements of physical observables and a dynamical property of the system [4].
I will finish my talk by presenting some promising future directions [5].

Voluntary movement initiation involves the modulation of large populations of motor cortical (M1) neurons around movement onset. Despite knowledge of the temporal dynamics of cortical ensembles that lead to movement, the spatial structure of these dynamics across the cortical sheet are poorly understood. Here, we show that the timing in attenuation of the beta frequency oscillation amplitude, a neural correlate of corticospinal excitability, forms a spatial gradient across M1 prior to movement onset with a defined beta attenuation orientation (BAO) from earlier to later attenuation times. We show that a similar propagating pattern is evident in the modulation times of populations of M1 neurons. Using various spatiotemporal patterns of intracortical microstimulation, we find that movement initiation is significantly slowed when stimulation is delivered against the BAO suggesting that movement initiation requires a precise spatio-temporal recruitment pattern in M1.

The polar vortex has "made headlines" in recent years, following anomalously cold Eastern US winters alongside continuing drought conditions in California which were associated with strong undulations in the tropospheric jet stream which bring cold polar air southward over the Eastern part of the continent, and warm dry conditions over the south west. Recent studies have associated these undulations with anomalous tropical Pacific SST anomalies. We propose that these jet undulations are associated with the North American part of the Circumglobal Teleconnection Pattern - a pair of zonally oriented waves of zonal wavenumber 5 which are in zonal quadrature with each other. While the PNA is associated with the first circumglobal wave pattern, Eastern North American extreme cold events are associated with the second pattern. The implications of this association regarding the physical drivers of such cold events will be discussed, in particular Asian wavepacket precursors and the possible relation to SST anomalies.