1,628 research outputs found
Effects of planform geometry on hover performance of a 2-meter-diameter model of a four-bladed rotor
Hover tests were conducted on three small scale rotors to evaluate the effects of blade planform taper on rotor hover performance. Tests were conducted on a rectangular swept-tip configuration, on a configuration with a 3 to 1 taper over the outboard 20 percent of the span, and on a configuration with a 5 to 1 taper over the outboard 20 percent of the blade span. The investigation covered a range of thrust coefficients from 0 to 0.0075 and a range of tip speeds from 300 to 600 ft/sec. The tests showed that both tapered configurations had better hover performance than the swept-tip rectangular configuration and that the 3 to 1 taper configuration was better than the 5 to 1 taper configuration. The test results were compared with predictions made with a prescribed wake analysis, a momentum analysis, and a simplified free wake analysis
Meat Juice serology underestimates prevalence of Salmonella in pig herds
Salmonella serology is used for classifying pig herds in risk categories in several national quality programs. Meat juice is used as test matrix in most of these programs. Two studies were done to compare the salmonella ELISA test results from meat juice with blood serum as a reference. Pig blood and meat samples for these studies were collected in one slaughterhouse. ELISA tests were done with a commonly applied commercial test. In the first study paired blood serum and meat juice samples from 182 pigs were collected and tested in two different laboratories. In the second study meat and blood samples were collected from 470 herds, over 20.000 samples for each matrix
Experiences with a risk based meat inspection standard in pigs
The European Union legislation provides several possibilities to modernize meat inspection. Improvement of food safety by active contribution of food business operators in the supply chain being responsible for food safety is envisaged in these new standards
Photoproduction of Baryons Decaying into N pi and N eta
A combined analysis of photoproduction data on \gamma p to \pi N, eta N was
performed including the data on K Lambda and K Sigma. The data are interpreted
in an isobar model with s--channel baryon resonances and pi, rho,(omega), K,
and K^* exchange in the t--channel. Three baryon resonances have a substantial
coupling to eta N, the well known N(1535)S_{11}, N(1720)P_{13}, and
N(2070)D_{15}. The inclusion of data with open strangeness reveals the presence
of further new resonances, N(1840)P_{11}, N(1875)D_{13} and N(2170)D_{13}.Comment: 13 pages, 14 figure
Leading particle effect, inelasticity and the connection between average multiplicities in {\bf } and {\bf } processes
The Regge-Mueller formalism is used to describe the inclusive spectrum of the
proton in collisions. From such a description the energy dependences of
both average inelasticity and leading proton multiplicity are calculated. These
quantities are then used to establish the connection between the average
charged particle multiplicities measured in {\bf } and {\bf } processes. The description obtained for the leading proton cross section
implies that Feynman scaling is strongly violated only at the extreme values of
, that is at the central region () and at the diffraction
region (), while it is approximately observed in the
intermediate region of the spectrum.Comment: 20 pages, 10 figures, to be published in Physical Review
Comment on "Quantum Scattering of Heavy Particles from a 10 K Cu(111) Surface"
In the original paper Althoff et al. (see ibid., vol.79, p.4429 (1997))
reported a study of scattering of thermal Ne, Ar, and Kr atoms from a Cu(111)
surface in which they assessed the corresponding Debye-Waller factor (DWF) as a
function of the particle mass m in a wide range of substrate temperature T. The
experiments were interpreted by the semiclassical DWF theory in which the
projectile moves on the classical recoilless trajectory and the surface
vibrations are quantized. Siber and Gumhalter claim that the experiments
described by Althoff et al. were carried out in the quantum scattering regime
in which the semiclassical scalings of Althoff et al. do not hold and the
semiclassical DWE significantly deviates from the exact quantum one both in the
low and high T limits. Hence, it is claimed, the quantum scattering data of
Althoff et al. cannot be reliably interpreted by the semiclassical theory.Comment: 1 page (2 figures) - comment in Phys. Rev. Let
Pion photoproduction on the nucleon in the quark model
We present a detailed quark-model study of pion photoproduction within the
effective Lagrangian approach. Cross sections and single-polarization
observables are investigated for the four charge channels, , , , and .
Leaving the coupling strength to be a free parameter, we obtain a
reasonably consistent description of these four channels from threshold to the
first resonance region. Within this effective Lagrangian approach, strongly
constrainted by the quark model, we consider the issue of double-counting which
may occur if additional {\it t}-channel contributions are included.Comment: Revtex, 35 pages, 16 eps figures; version to appear on PR
PRAS40 suppresses atherogenesis through inhibition of mTORC1-dependent pro-inflammatory signaling in endothelial cells
Endothelial pro-inflammatory activation plays a pivotal role in atherosclerosis, and many pro-inflammatory and atherogenic signals converge upon mechanistic target of rapamycin (mTOR). Inhibitors of mTOR complex 1 (mTORC1) reduced atherosclerosis in preclinical studies, but side effects including insulin resistance and dyslipidemia limit their clinical use in this context. Therefore, we investigated PRAS40, a cell type-specific endogenous modulator of mTORC1, as alternative target. Indeed, we previously found PRAS40 gene therapy to improve metabolic profile; however, its function in endothelial cells and its role in atherosclerosis remain unknown. Here we show that PRAS40 negatively regulates endothelial mTORC1 and pro-inflammatory signaling. Knockdown of PRAS40 in endothelial cells promoted TNFα-induced mTORC1 signaling, proliferation, upregulation of inflammatory markers and monocyte recruitment. In contrast, PRAS40-overexpression blocked mTORC1 and all measures of pro-inflammatory signaling. These effects were mimicked by pharmacological mTORC1-inhibition with torin1. In an in vivo model of atherogenic remodeling, mice with induced endothelium-specific PRAS40 deficiency showed enhanced endothelial pro-inflammatory activation as well as increased neointimal hyperplasia and atherosclerotic lesion formation. These data indicate that PRAS40 suppresses atherosclerosis via inhibition of endothelial mTORC1-mediated pro-inflammatory signaling. In conjunction with its favourable effects on metabolic homeostasis, this renders PRAS40 a potential target for the treatment of atherosclerosis
Baryon resonances and polarization transfer in hyperon photoproduction
A partial wave analysis is presented of data on photoproduction of hyperons
including single and double polarization observables. The large spin transfer
probability reported by the CLAS collaboration can be successfully described
with an isobar partial wave analysis.Comment: 12 pages, 9 figure
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