New vacuum solutions of conformal Weyl gravity

The Bach equation, i.e., the vacuum field equation following from the Lagrangian L=C_{ijkl}C^{ijkl}, will be completely solved for the case that the metric is conformally related to the cartesian product of two 2-spaces; this covers the spherically and the plane symmetric space-times as special subcases. Contrary to other approaches, we make a covariant 2+2-decomposition of the field equation, and so we are able to apply results from 2-dimensional gravity. Finally, some cosmological solutions will be presented and discussed.Comment: 15 pages, LaTeX, no figures, submitted to J. Math. Phy

Fano interference effect on the transition spectrum of single electron transistors

We theoretically study the intraband transition spectrum of single electron transistors (SETs) composed of individual self-assembled quantum dots. The polarization of SETs is obtained by using the nonequilibrium Green's function technique and the Anderson model with three energy levels. Owing to nonradiative coupling between two excited states through the continuum of electrodes, the Fano interference effect significantly influences the peak position and intensity of infrared wavelength single-photon spectrum.Comment: 4 pages, 5 figure

Alas, the dark matter structures were not that trivial

The radial density profile of dark matter structures has been observed to have an almost universal behaviour in numerical simulations, however, the physical reason for this behaviour remains unclear. It has previously been shown that if the pseudo phase-space density, rho/sigma_d^epsilon, is a beautifully simple power-law in radius, with the "golden values" epsilon=3 and d=r (i.e., the phase-space density is only dependent on the radial component of the velocity dispersion), then one can analytically derive the radial variation of the mass profile, dispersion profile etc. That would imply, if correct, that we just have to explain why rho/sigma^3_r ~r^{-alpha}, and then we would understand everything about equilibrated DM structures. Here we use a set of simulated galaxies and clusters of galaxies to demonstrate that there are no such golden values, but that each structure instead has its own set of values. Considering the same structure at different redshifts shows no evolution of the phase-space parameters towards fixed points. There is also no clear connection between the halo virialized mass and these parameters. This implies that we still do not understand the origin of the profiles of dark matter structures.Comment: 4 pages, 3 figures, accepted for publication in ApJ

Reaction mechanisms involved in the production of neutron-rich isotopes

The reaction mechanisms best suited for the production of neutron-rich nuclei, fragmentation and fission, are discussed. Measurements of the production cross sections of reaction residues together with model calculations allow to conclude about the expected production rates of neutron-rich isotopes in future facilities.Comment: 9 pages, 8 figures Proceedings of the Third International Conference on Fission and Properties of Neutron-Rich Nuclei November 3-9, 2002, Sanibel Island, Florida, US