We develop an analytical expression for the self-energy of the infinite-dimensional Hubbard model that is correct in a number of different limits. The approach represents a generalization of the iterative perturbation theory to arbitrary fillings. In the weak-coupling regime perturbation theory to second order in the interaction U is recovered. The theory is exact in the atomic limit. The high-energy behavior of the self-energy up to order 1/E 2 and thereby the first four moments of the spectral density are reproduced correctly. Referring to a standard strong-coupling moment method, we analyze the limit U → ∞. Different modifications of the approach are discussed and tested by comparing with the results of an exact diagonalization study.

The sum rule for the moments of the spectral density is discussed for the single-band Hubbard model. It is shown that respecting the sum rule up to the order m 3 is conceptually important for a qualitatively correct description of the quasi-particle band structure in the strong-correlation regime. Different analytical approximations for the self-energy are analyzed with respect to their compatibility with the moment sum rule. To estimate the practical usefulness of the sum rule, correlation functions and dynamical quantities are determined. The results obtained within the various approximation schemes of different complexity are compared with each other and also with essentially exact results available for infinite-dimensional lattices. It turns out that the m 3 moment is rather unimportant for the paramagnetic phase on the hyper-cubic lattice. Contrary, it decisively influences the magnetic phase boundary as well as the critical temperature for the ferromagnetic phase on an f.c.c.-type lattice.

Basal cell carcinoma (BCC) is a subtype of nonmelanoma skin cancer (NMSC), with an increasing incidence worldwide. Currently, excision of the tumour with histological control is the standard therapy. However, high incidence rates have led to concern about the economic burden imposed by BCC management in many countries. Imiquimod is a member of a novel class of immune response modifiers (IRM), which works by using the toll-like receptor (TLR)-7. Although the exact mode of action is so far unknown, it is suggested to induce the expression of different cytokines like interleukin (IL)-1, IL-6, IL-12, interferon (IFN)-alpha and tumour necrosis factor (TNF)-alpha, which stimulate or enhance both the innate immune system and the cell-mediated immune response. Pre-clinical studies have indicated the potential of this TLR-7 agonist for the treatment of precancers and tumours in humans. A number of Phase II trials have demonstrated the efficacy of imiquimod for the treatment of BCC, although the most appropriate dosing regimen is being confirmed in Phase III studies. Imiquimod 5% cream for the treatment of mainly superficial BCC appears to be an effective and well-tolerated treatment option.

The Charge Exchange Recombination Spectroscopy (CXRS) diagnostic has become a routine diagnostic on almost all major high temperature fusion experimental devices. For the optimised stellarator W7-X, a highly flexible and extensive CXRS diagnostic has been built to provide high-resolution local measurements of several important plasma parameters using the recently commissioned neutral beam heating. This paper outlines the design specifics of the W7-X CXRS system and gives examples of the initial results obtained including typical ion temperature profiles for several common heating scenarios, toroidal flow and radial electric field derived from velocity measurements, beam attenuation via beam emission spectra and finally, normalised impurity density profiles under some typical plasma conditions.

We investigate the single-impurity Anderson model by means of the recently introduced modified perturbation theory. This approximation scheme yields reasonable results away from the symmetric case. The agreement with exactly known results for the symmetric case is checked, and results for the non-symmetric case are presented. With decreasing conduction band occupation, the breakdown of the screening of the local moment is observed. In the crossover regime between Kondo limit and mixed-valence regime, an enhanced zero-temperature susceptibility is found.