Manifestation of photonic band structure in small clusters of spherical particles

We study the formation of the photonic band structure in small clusters of dielectric spheres. The first signs of the band structure, an attribute of an infinite crystal, can appear for clusters of 5 particles. Density of resonant states of a cluster of 32 spheres may exhibit a well defined structure similar to the density of electromagnetic states of the infinite photonic crystal. The resonant mode structure of finite-size aggregates is shown to be insensitive to random displacements of particles off the perfect lattice positions as large as half-radius of the particle. The results were obtained by an efficient numerical method, which relates the density of resonant states to the the scattering coefficients of the electromagnetic scattering problem. Generalized multisphere Mie (GMM) solution was used to obtain scattering matrix elements. These results are important to miniature photonic crystal design as well as understanding of light localization in dense random media.Comment: 4 pages, 2 figure

Vortex dissipation and level dynamics for the layered superconductors with impurities

We study parametric level statistics of the discretized excitation spectra inside a moving vortex core in layered superconductors with impurities. The universal conductivity is evaluated numerically for the various values of rescaled vortex velocities $\kappa$ from the clean case to the dirty limit case. The random matrix theoretical prediction is verified numerically in the large $\kappa$ regime. On the contrary in the low velocity regime, we observe $\sigma_{xx} \propto \kappa^{2/3}$ which is consistent with the theoretical result for the super-clean case, where the energy dissipation is due to the Landau-Zener transition which takes place at the points called ``avoided crossing''.Comment: 10 pages, 4 figures, REVTeX3.

Temporal fluctuations of waves in weakly nonlinear disordered media

We consider the multiple scattering of a scalar wave in a disordered medium with a weak nonlinearity of Kerr type. The perturbation theory, developed to calculate the temporal autocorrelation function of scattered wave, fails at short correlation times. A self-consistent calculation shows that for nonlinearities exceeding a certain threshold value, the multiple-scattering speckle pattern becomes unstable and exhibits spontaneous fluctuations even in the absence of scatterer motion. The instability is due to a distributed feedback in the system "coherent wave + nonlinear disordered medium". The feedback is provided by the multiple scattering. The development of instability is independent of the sign of nonlinearity.Comment: RevTeX, 15 pages (including 5 figures), accepted for publication in Phys. Rev.

Rheumatologists' guideline adherence in rheumatoid arthritis: a randomised controlled study on electronic decision support, education and feedback

Item does not contain fulltextOBJECTIVES: To assess the effects of education, feedback and a computerised decision support system (CDSS) versus education and feedback alone on rheumatologists' rheumatoid arthritis (RA) guideline adherence. METHODS: A single-centre, randomised controlled pilot study was performed among clinicians (rheumatologists, residents and physician assistants; n=20) working at the study centre, with a 1:1 randomisation of included clinicians. A standardized sum score (SSS) on guideline adherence was used as the primary outcome (patient level). The SSS was calculated from 13 dichotomous indicators on quality of RA monitoring, treatment and follow-up. The randomised controlled design was combined with a before-after design in the control group to assess the effect education and feedback alone. RESULTS: Twenty clinicians (mean age 44.3+/-10.9 years; 55% female) and 990 patients (mean age 62 +/- 13 years; 69% female; 72% rheumatoid factor and/or anti-CCP positive) were included. Addition of CDSS to education and feedback did not result in significant better quality of RA care than education and feedback alone (SSS difference 0.02; 95%-CI -0.04 to 0.08; p=0.60). However, before/after comparison showed that education and feedback alone resulted in a significant increase in the SSS from 0.58 to 0.64 (difference 0.06; 95%-CI 0.02 to 0.11; p<0.01). CONCLUSIONS: Our results suggest that CDSS did not have added value with regard to guideline adherence, whereas education and feedback can lead to a small but significant improvement of guideline adherence