Temperature and Voltage Probes Far from Equilibrium

We consider an open system of non-interacting electrons consisting of a small sample connected to several reservoirs and temperature or voltage probes. We study the non-linear system of equations that determines the probe parameters. We show that it has a unique solution, which can be computed with a fast converging iterative algorithm. We illustrate our method with two well-known models: the three-terminal system and the open Aharovov-Bohm interferometer

Cosmological Evolution on Self-Tuned Branes and the Cosmological Constant

We consider the cosmological evolution of a bulk scalar field and ordinary matter living on the brane world in the light of the constraints imposed by the matter dominated cosmological evolution and a small cosmological constant now. We rule out models with a self-tuned minimum of the four dimensional potential as they would lead to rapid oscillations of the Hubble parameter now. A more natural framework is provided by supergravity in singular spaces where the brane coupling and the bulk potential are related by supersymmetry leading to a four dimensional run-away potential. For late times we obtain an accelerating universe due to the breaking of supersymmetry on the brane with an acceleration parameter of q_0=-4/7 and associated equation of state omega=-5/7.Comment: 24 pages, JHEP styl