A New Spin-Orbit Induced Universality Class in the Quantum Hall Regime ?

Using heuristic arguments and numerical simulations it is argued that the critical exponent $\nu$ describing the localization length divergence at the quantum Hall transition is modified in the presence of spin-orbit scattering with short range correlations. The exponent is very close to $\nu=4/3$, the percolation correlation length exponent, the prediction of a semi-classical argument. In addition, a region of weakly localized regime, where the localization length is exponentially large, is conjectured.Comment: 4 two-column pages including 4 eps figure

Coupling between leg muscle activation and EEG during normal walking, intentional stops, and freezing of gait in Parkinson's disease

In this paper, we apply novel techniques for characterizing leg muscle activation patterns via electromyograms (EMGs) and for relating them to changes in electroencephalogram (EEG) activity during gait experiments. Specifically, we investigate changes of leg-muscle EMG amplitudes and EMG frequencies during walking, intentional stops, and unintended freezing-of-gait (FOG) episodes. FOG is a frequent paroxysmal gait disturbance occurring in many patients suffering from Parkinson's disease (PD). We find that EMG amplitudes and frequencies do not change significantly during FOG episodes with respect to walking, while drastic changes occur during intentional stops. Phase synchronization between EMG signals is most pronounced during walking in controls and reduced in PD patients. By analyzing cross-correlations between changes in EMG patterns and brain-wave amplitudes (from EEGs), we find an increase in EEG-EMG coupling at the beginning of stop and FOG episodes. Our results may help to better understand the enigmatic pathophysiology of FOG, to differentiate between FOG events and other gait disturbances, and ultimately to improve diagnostic procedures for patients suffering from PD. Copyright © 2019 Günther, Bartsch, Miron-Shahar, Hassin-Baer, Inzelberg, Kurths, Plotnik and Kantelhardt

Metallic behavior and related phenomena in two dimensions

For about twenty years, it has been the prevailing view that there can be no metallic state or metal-insulator transition in two dimensions in zero magnetic field. In the last several years, however, unusual behavior suggestive of such a transition has been reported in a variety of dilute two-dimensional electron and hole systems. The physics behind these observations is presently not understood. We review and discuss the main experimental findings and suggested theoretical models.Comment: To be published in Rev. Mod. Phy

2019-2020 Hu Shih Distinguished Lecture: Meir Shahar

Video of lecture with presentation slides edited into video.Meir Shahar, Shoul N. Eisenberg Chair for East Asian Affairs, Tel Aviv University - Our ancestors depended upon beasts of burden for a living. In the Chinese case this dependence was reflected in the religious sphere. Chinese religion featured deities responsible for the wellbeing of draft animals. The two principal ones were the Horse King (divine protector of equines) and the Ox King (tutelary deity of bovines). This lecture will examine the ecological background and historical evolution of these animal-protecting cults. Professor Shahar will survey the Horse King's and Ox King's diverse clientele, from peasants who relied upon the water buffalo to plough their rice fields to cavalrymen whose success in battle depended upon their chargers' performance. Particular attention will be given to the theological standing of animals as reflected in their tutelary divinities' cults. In some cases, the animal itself was regarded as a deity who sacrificed himself for humanity’s sake. Chinese Buddhist scriptures described the ox as a bodhisattva who out of pity for the toiling peasant chose to be incarnated as his beast of burden.Cornell East Asia Program1_fumvlft