336 research outputs found
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
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