29,936 research outputs found

    Normal Histology of Brown Fat of Certain Arkansas Bats

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    A Battle of Taste and Environmental Convictions for Ecolabeled Seafood: A Choice Experiment

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    This paper describes a choice experiment addressing preferences for ecolabeled seafood, in which the experimental design allows for choices among various fresh seafood products. The primary emphasis is the potential trade-off between taste (i.e., a favored species) and the presence of an ecolabel, when multiple seafood products are available.Consumer/Household Economics,

    High Velocity Burner Rig Oxidation and Thermal Fatigue Behavior of Si3N4- and SiC Base Ceramics to 1370 Deg C

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    One SiC material and three Si3N4 materials including hot-pressed Si3N4 as a baseline were exposed in a Mach-1-gas-velocity burner rig simulating a turbine engine environment. Criteria for the materials selection were: potential for gas-turbine usage, near-net-shape fabricability and commercial/domestic availability. Cyclic exposures of test vanes up to 250 cycles (50 hr at temperature) were at leading-edge temperatures to 1370 C. Materials and batches were compared as to weight change, surface change, fluorescent penetrant inspection, and thermal fatigue behavior. Hot-pressed Si3N4 survived the test to 1370 C with slight weight losses. Two types of reaction-sintered Si3N4 displayed high weight gains and considerable weight-change variability, with one material exhibiting superior thermal fatigue behavior. A siliconized SiC showed slight weight gains, but considerable batch variability in thermal fatigue

    Preparation of monotectic alloys having a controlled microstructure by directional solidification under dopant-induced interface breakdown

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    Monotectic alloys having aligned spherical particles of rods of the minor component dispersed in a matrix of the major component are prepared by forming a melt containing predetermined amounts of the major and minor components of a chosen monotectic system, providing in the melt a dopant capable of breaking down the liquid solid interface for the chosen alloy, and directionally solidfying the melt at a selected temperature gradient and a selected rate of movement of the liquid-solid interface (growth rate). Shaping of the minor component into spheres or rods and the spacing between them are controlled by the amount of dopant and the temperature gradient and growth rate values. Specific alloy systems include Al Bi, Al Pb and Zn Bi, using a transition element such as iron

    Performance of rocket nozzle materials with several solid propellants

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    Erosion resistance and thermal stress cracking tests of rocket nozzle materials with solid propellant

    Microwave hydrology: A trilogy

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    Microwave hydrology, as the term in construed in this trilogy, deals with the investigation of important hydrological features on the Earth's surface as they are remotely, and passively, sensed by orbiting microwave receivers. Microwave wavelengths penetrate clouds, foliage, ground cover, and soil, in varying degrees, and reveal the occurrence of standing liquid water on and beneath the surface. The manifestation of liquid water appearing on or near the surface is reported by a microwave receiver as a signal with a low flux level, or, equivalently, a cold temperature. Actually, the surface of the liquid water reflects the low flux level from the cosmic background into the input terminals of the receiver. This trilogy describes and shows by microwave flux images: the hydrological features that sustain Lake Baykal as an extraordinary freshwater resource; manifestations of subsurface water in Iran; and the major water features of the Congo Basin, a rain forest

    Optical Turbulence Measurements and Models for Mount John University Observatory

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    Site measurements were collected at Mount John University Observatory in 2005 and 2007 using a purpose-built scintillation detection and ranging system. Cn2(h)C_n^2(h) profiling indicates a weak layer located at 12 - 14 km above sea level and strong low altitude turbulence extending up to 5 km. During calm weather conditions, an additional layer was detected at 6 - 8 km above sea level. V(h)V(h) profiling suggests that tropopause layer velocities are nominally 12 - 30 m/s, and near-ground velocities range between 2 -- 20 m/s, dependent on weather. Little seasonal variation was detected in either Cn2(h)C_n^2(h) and V(h)V(h) profiles. The average coherence length, r0r_0, was found to be 7±17 \pm 1 cm for the full profile at a wavelength of 589 nm. The average isoplanatic angle, θ0\theta_0, was 1.0±0.11.0 \pm 0.1 arcsec. The mean turbulence altitude, h0ˉ\bar{h_0}, was found to be 2.0±0.72.0\pm0.7 km above sea level. No average in the Greenwood frequency, fGf_G, could be established due to the gaps present in the \vw\s profiles obtained. A modified Hufnagel-Valley model was developed to describe the Cn2(h)C_n^2(h) profiles at Mount John, which estimates r0r_0 at 6 cm and θ0\theta_0 at 0.9 arcsec. A series of V(h)V(h) models were developed, based on the Greenwood wind model with an additional peak located at low altitudes. Using the Cn2(h)C_n^2(h) model and the suggested V(h)V(h) model for moderate ground wind speeds, fGf_G is estimated at 79 Hz.Comment: 14 pages; accepted for publication in PAS
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