Wave Propagation in Nonlocally Coupled Oscillators With Noise

The onset of undamped wave propagation in noisy self-oscillatory media is identified with a Hopf bifurcation of the corresponding effective dynamical system obtained by properly renormalizing the effects of noise. We illustrate this fact on a dense array of nonlocally coupled phase oscillators for which a mean-field idea works exactly in deriving such effective dynamical equations.Comment: 4 page

Shot Noise Induced by Nonequilibrium Spin Accumulation

When an electric current passes across a potential barrier, the partition process of electrons at the barrier gives rise to the shot noise, reflecting the discrete nature of the electric charge. Here we report the observation of excess shot noise connected with a spin current which is induced by a nonequilibrium spin accumulation in an all-semiconductor lateral spin-valve device. We find that this excess shot noise is proportional to the spin current. Additionally, we determine quantitatively the spin-injection-induced electron temperature by measuring the current noise. Our experiments show that spin accumulation driven shot noise provides a novel means of investigating nonequilibrium spin transport.Comment: 5 pages and Supplemental Materia

Scanning Electron Microscopic Investigations of the Shape of Toothbrush Filaments with Various Brushing Techniques I. The most effective case of plaque removal

Using 30 second-year students of the Matsumoto Dental College, School of Dental Hygiene as subjects, we performed investigations on toothbrush filament shape changes while using 4 test toothbrushes and 4 different brushing techniques over 2 week periods. Also, observation by scanning electron microscopy was done for the toothbrush which yielded the best plaque removal. The results were as follows: 1. The edge of the brush filament was worn almost rectangularly along the longitudinal axis after 2 weeks of using the Bass and scrub techniques. 2. The filament edge tended to become sharper with the rolling and modified Stillman techniques. The round-cut and moving area of the toothbrush body were worn significantly using the rolling and modified Stillman techniques. 3. The toothbrush filaments with every brushing technique were worn significantly. Deep ditches, scratches and peeling were frequently observed with the rolling and modified Stillman techniques