Time-Spectral Rotorcraft Simulations on Overset Grids

The Time-Spectral method is derived as a Fourier collocation scheme and applied to NASA's overset Reynolds-averaged Navier-Stokes (RANS) solver OVERFLOW. The paper outlines the Time-Spectral OVERFLOWimplementation. Successful low-speed laminar plunging NACA 0012 airfoil simulations demonstrate the capability of the Time-Spectral method to resolve the highly-vortical wakes typical of more expensive three-dimensional rotorcraft configurations. Dealiasing, in the form of spectral vanishing viscosity (SVV), facilitates the convergence of Time-Spectral calculations of high-frequency flows. Finally, simulations of the isolated V-22 Osprey tiltrotor for both hover and forward (edgewise) flight validate the three-dimensional Time-Spectral OVERFLOW implementation. The Time-Spectral hover simulation matches the time-accurate calculation using a single harmonic. Significantly more temporal modes and SVV are required to accurately compute the forward flight case because of its more active, high-frequency wake

Antibodies against a Surface Protein of Streptococcus pyogenes Promote a Pathological Inflammatory Response

Streptococcal toxic shock syndrome (STSS) caused by Streptococcus pyogenes is a clinical condition with a high mortality rate despite modern intensive care. A key feature of STSS is excessive plasma leakage leading to hypovolemic hypotension, disturbed microcirculation and multiorgan failure. Previous work has identified a virulence mechanism in STSS where M1 protein of S. pyogenes forms complexes with fibrinogen that activate neutrophils to release heparin-binding protein (HBP), an inducer of vascular leakage. Here, we report a marked inter-individual difference in the response to M1 protein–induced HBP release, a difference found to be related to IgG antibodies directed against the central region of the M1 protein. To elicit massive HBP release, such antibodies need to be part of the M1 protein–fibrinogen complexes. The data add a novel aspect to bacterial pathogenesis where antibodies contribute to the severity of disease by promoting a pathologic inflammatory response

Protease inhibitors in inflammatory synovial effusions.

Granulocyte lysosomal enzymes can potentially participate in cartilage degradation in inflammatory arthritides. However, we have shown that the quantity of several such enzymes in an inflammatory synovial effusion correlates negatively with the degree of radiographic damage of the joint from which the fluid was sampled. In the current work the quantity of the following 5 protease inhibitors was determined immunochemically in the same fluids: alpha 1 antitrypsin, alpha 1-antichymotrypsin, alpha 2-macroglobulin, inter-alpha-trypsin inhibitor, and Cl esterase inhibitor. These inhibitors are generally covariate and correlate positively with the total protein in the fluid as well as the number of granulocytes and the concentration of granulocyte lysosomal enzymes in the fluid. As did the lysosomal enzymes, the protease inhibitors correlate negatively with radiographic destruction. It is likely that lysosomal enzymes in solution in inflammatory synovial effusions are rendered effete by the presence of protease inhibitors