Density Fluctuations in an Electrolyte from Generalized Debye-Hueckel Theory

Near-critical thermodynamics in the hard-sphere (1,1) electrolyte is well described, at a classical level, by Debye-Hueckel (DH) theory with (+,-) ion pairing and dipolar-pair-ionic-fluid coupling. But DH-based theories do not address density fluctuations. Here density correlations are obtained by functional differentiation of DH theory generalized to {\it non}-uniform densities of various species. The correlation length $\xi$ diverges universally at low density $\rho$ as $(T\rho)^{-1/4}$ (correcting GMSA theory). When $\rho=\rho_c$ one has $\xi\approx\xi_0^+/t^{1/2}$ as $t\equiv(T-T_c)/T_c\to 0+$ where the amplitudes $\xi_0^+$ compare informatively with experimental data.Comment: 5 pages, REVTeX, 1 ps figure included with epsf. Minor changes, references added. Accepted for publication in Phys. Rev. Let

Robust Stability Analysis: a Tool to Assess the Impact of Biodynamic Feedthrough on Rotorcraft

Biodynamic feedthrough (BDFT) may significantly affect the closed-loop behavior of rotorcraft, reducing the stability and increasing the proneness to Rotorcraft-Pilot Couplings (RPC). Leveraging robust stability analysis, the inherently uncertain pilot BDFT can be treated as the uncertain portion of a feedback system, allowing analytical, numerical or graphical determination of proneness to RPC by comparing robust stability margins of helicopter models with BDFT data. The application of the proposed approach to collective bounce is exemplified using simple analytical helicopter and pilot BDFT models, and applied to detailed helicopter models and BDFT measurement data

An important step towards completing the rheumatoid arthritis cycle

In the previous issue of Arthritis Research & Therapy data are presented showing that circulating immune complexes containing citrullinated fibrin(ogen) are present in anti-citrullinated protein antibody-positive rheumatoid arthritis patients, and that such immune complexes co-localize with complement factor C3 in the rheumatoid synovium. These results corroborate the idea that citrullination is intimately involved in the pathophysiology of rheumatoid arthritis and complete our model (the rheumatoid arthritis cycle) for the development and chronic nature of this disease