Helicopter Blade-Vortex Interaction Noise with Comparisons to CFD Calculations

A comparison of experimental acoustics data and computational predictions was performed for a helicopter rotor blade interacting with a parallel vortex. The experiment was designed to examine the aerodynamics and acoustics of parallel Blade-Vortex Interaction (BVI) and was performed in the Ames Research Center (ARC) 80- by 120-Foot Subsonic Wind Tunnel. An independently generated vortex interacted with a small-scale, nonlifting helicopter rotor at the 180 deg azimuth angle to create the interaction in a controlled environment. Computational Fluid Dynamics (CFD) was used to calculate near-field pressure time histories. The CFD code, called Transonic Unsteady Rotor Navier-Stokes (TURNS), was used to make comparisons with the acoustic pressure measurement at two microphone locations and several test conditions. The test conditions examined included hover tip Mach numbers of 0.6 and 0.7, advance ratio of 0.2, positive and negative vortex rotation, and the vortex passing above and below the rotor blade by 0.25 rotor chords. The results show that the CFD qualitatively predicts the acoustic characteristics very well, but quantitatively overpredicts the peak-to-peak sound pressure level by 15 percent in most cases. There also exists a discrepancy in the phasing (about 4 deg) of the BVI event in some cases. Additional calculations were performed to examine the effects of vortex strength, thickness, time accuracy, and directionality. This study validates the TURNS code for prediction of near-field acoustic pressures of controlled parallel BVI

What Makes People Anxious About Life after the Age of 65?- Evidence from International Survey Research in Japan, the United States, and China

In order to respond to the social security needs of an increasingly aged population, many governments with limited budgets are required to focus available resources on the direct causes of people's anxieties about aging. This study investigated the causes of people's anxieties about life after the age of 65 using household data from countries with different social contexts: Japan, the United States, and China. This research uncovered three major findings. First, the speed of population aging does not always make people anxious about life at an older age. Second, high financial status effectively lessens people's levels of anxiety about their older years in Japan and the United States. Third, living with a child does not necessarily lessen people's concern about life after 65

Pathogenesis of Shigella diarrhoea: XVII- A mammalian cell membrane glycolipid, Gb<SUB>3</SUB>, is required but sufficient to confirm sensitivity to shiga toxin

Shiga toxin recognizesa galactose-α1 → 4-galactose terminal glycolipid,globotriaosylceramide (Gb<SUB>3</SUB>), in sensitive mammalian cells and is translocated by endocytosis to the cytoplasm, where it blocks protein synthesis. To determine if Gb<SUB>3</SUB> is both required and sufficient for toxicity, Gb<SUB>3</SUB> content in cells was altered by blocking key biosynthetic or degradative path enzymes with specific inhibitors. The resulting decrease or increase in cellular Gb<SUB>3</SUB> was associated with a decrease or increase in binding of and response to Shiga toxin. Toxin-resistant Gb<SUB>3</SUB>-deficient variants of sensitive cells fused with liposomes containing Gb<SUB>3</SUB> but not globotetraosylceramide (Gb<SUB>4</SUB>) became susceptible, whereas fusion of Gb<SUB>3</SUB> liposomes to naturally resistant Gb<SUB>3</SUB>-deficient CHD cells increased toxin binding but not cytotoxicity. These data demonstrate that Gb<SUB>3</SUB> is required, but not sufficient, for the action of Shiga toxin and suggest the existence of a toxin translocation mechanism linked to surface glycolipids that is not expressed in CHD cells