Political economy, political class, and political system in recivilianized Nigeria

African Studies Center Working Paper No. 4

The heat kernel expansion for the electromagnetic field in a cavity

We derive the first six coefficients of the heat kernel expansion for the electromagnetic field in a cavity by relating it to the expansion for the Laplace operator acting on forms. As an application we verify that the electromagnetic Casimir energy is finite.Comment: 12 page

Phase coherent transport in a side-gated mesoscopic graphite wire

We investigate the magnetotransport properties of a thin graphite wire resting on a silicon oxide substrate. The electric field effect is demonstrated with back and side gate electrodes. We study the conductance fluctuations as a function of gate voltage, magnetic field and temperature. The phase coherence length extracted from weak localization is larger than the wire width even at the lowest carrier densities making the system effectively one-dimensional. We find that the phase coherence length increases linearly with the conductivity suggesting that at 1.7 K dephasing originates mainly from electron-electron interactions.Comment: 5 pages, 4 figure

Parametric resonance and spin-charge separation in 1D fermionic systems

We show that the periodic modulation of the Hamiltonian parameters for 1D correlated fermionic systems can be used to parametrically amplify their bosonic collective modes. Treating the problem within the Luttinger liquid picture, we show how charge and spin density waves with different momenta are simultaneously amplified. We discuss the implementation of our predictions for cold atoms in 1D modulated optical lattices, showing that the fermionic momentum distribution directly provides a clear signature of spin-charge separation.Comment: 6 pages, 3 figures, published versio