Topological Casimir effect in power-law FRW cosmologies

We investigate the vacuum expectation values of the field squared and the energy-momentum tensor for a massless scalar field with general curvature coupling parameter in spatially flat Friedmann-Robertson-Walker universes with an arbitrary number of toroidally compactified dimensions. When the comoving lengths of the compact dimensions are short compared to the Hubble length, the topological parts coincide with those for a conformal coupling. This limit corresponds to the adiabatic approximation. In the opposite limit of large comoving lengths of the compact dimensions, in dependence of the curvature coupling parameter, two regimes are realized with monotonic or oscillatory behavior of the vacuum expectation values.Comment: 5 pages, 1 figure, Contribution to Proceedings of QFEXT09, 21-25 September, 2009, Oklahoma, US

Policy maker-Student relationships: Evidence From The Armenian Higher Education System

This work discusses a policy maker-student relation taking into account educational standards, asymmetric information and incentives for students to study well. The problems discussed are the characteristics of developing countries. To define educational standards is not enough for an efficient educational system. Supervision is desired to minimize moral hazard and not to loose the best students. Especially in developing countries where there is no flexible loan market, the state financing of students who are studying well could be an appropriate incentive for students to study with more enthusiasm and do their best to keep their position in the University

Disorder-induced magnetooscillations in bilayer graphene at high bias

Energy spectrum of biased bilayer graphene near the bottom has a "Mexican-hat"-like shape. For the Fermi level within the Mexican hat we predict that, apart from conventional magnetooscillations which vanish with temperature, there are additional magnetooscillations which are weakly sensitive to temperature. These oscillations are also insensitive to a long-range disorder. Their period in magnetic field scales with bias, V, as V^2. The origin of these oscillations is the disorder-induced scattering between electron-like and hole-like Fermi-surfaces, specific for Mexican hat.Comment: 5 pages, 2 figure