The longitudinal resistivity of two dimensional (2D) electrons placed in strong magnetic field is significantly reduced by applied electric field, an effect which is studied in a broad range of magnetic fields B and temperatures T in GaAs quantum wells with high electron density. The data are found to be in good agreement with theory, considering the strong nonlinearity of the resistivity as result of non-uniform spectral diffusion of the 2D electrons. Inelastic processes limit the diffusion. Comparison with the theory yields the inelastic scattering time τin of the two dimensional electrons. In the temperature range T = 2 − 10K for overlapping Landau levels, the inelastic scattering rate 1/τin is found to be proportional to T 2 , indicating a dominant contribution of the electronelectron scattering to the inelastic electron relaxation. In a strong magnetic field, the nonlinear resistivity demonstrates scaling behavior, indicating a specific regime of electron heating of wellseparated Landau levels. In this regime the inelastic scattering rate is found to be proportional to T 3 , suggesting the electron-phonon scattering as the dominant mechanism of the inelastic relaxation. At low temperatures and separated Landau levels an additional regime of the inelastic electron relaxation is observed: τin ∼ T −1.26 .

A new type of compound can be got by docking the active site of acceptor and the active site of ligand. In general, active sites of the molecule are often located in the concave-convex regions. In this paper, we propose a new method which combines discrete Gaussian curvature with normal to determine geometric shape of the molecular surface of protein. Firstly, we compute the normal and Gaussian curvature of all vertices of the triangular mesh model that present a molecular surface. Then we choose a certain number of vertices ac-cording to Gaussian curvature of each vertex on the mesh. By doing so, the shape of the region consisting of those vertices is determined, that is the region is concave or convex.

Electric field induced, spectacular reduction of longitudinal resistivity of two dimensional electrons placed in strong magnetic field is studied in broad range of temperatures. The data are in good agreement with theory, considering the strong nonlinearity of the resistivity as result of non-uniform spectral diffusion of 2D electrons induced by the electric field. Comparison with the theory gives inelastic scattering time τin of the 2D electrons. In temperature range T = 2 - 20 K for overlapping Landau levels, the inelastic scattering rate 1/τin is found to be proportional to T2, indicating dominant contribution of the electron-electron interaction to the inelastic electron relaxation. At strong magnetic field, at which Landau levels are well separated, the inelastic scattering rate is proportional to T3 at high temperatures. We suggest the electron-phonon scattering as the dominant mechanism of the inelastic electron relaxation in this regime. At low temperature and separated Landau levels an additional regime of the inelastic electron relaxation is observed: τin ~ T-1.26.