65,907 research outputs found

    Atlas and zoogeography of common fishes in the Bering Sea and northeastern Pacific

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    The geographic and depth frequency distribution of 124 common demersal fish species in the northeastern Pacific were plotted from data on me at the Northwest and Alaska Fisheries Center (NWAFC), National Marine Fisheries Service. The data included catch records of fishes and invertebrates from 24,881 samples taken from the Chukchi Sea, throughout the Bering Sea, Aleutian Basin, Aleutian Archipelago, and the Gulf of Alaska, and from southeastern Alaska south to southern California. Samples were collected by a number of agencies and institutions over a 30-year period (1953-83), but were primarily from NWAFC demersal trawls. The distributions of all species with 100 or more occurrences in the data set were plotted by computer. Distributions plotted from these data were then compared with geographic and depth-range limits given in the literature. These data provide new range extensions (geographic, depth, or both) for 114 species. Questionable extensions are noted, the depth ranges determined for 95% of occurrences, and depths of most frequent occurrence are recorded. Ranges of the species were classified zoogeographically, according to life zone, and with regard to the depth zone of greatest occurrence. Because most species examined have broad geographic ranges, they do not provide the best information for testing the validity of proposed zoogeographic province boundaries. Because of the location of greatest sampling effort and methods used in sampling, most fIShes examined were eastern boreal Pacific, sublittoral-bathyal (outer shelf) species. (PDF file contains 158 pages.

    Spinor Parallel Propagator and Green's Function in Maximally Symmetric Spaces

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    We introduce the spinor parallel propagator for maximally symmetric spaces in any dimension. Then, the Dirac spinor Green's functions in the maximally symmetric spaces R^n, S^n and H^n are calculated in terms of intrinsic geometric objects. The results are covariant and coordinate-independent.Comment: 7 page

    Experimental effects of wing location on wing-body pressures at supersonic speeds

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    An experimental study was performed at supersonic speeds to measure wing and body spanwise pressure distributions on an axisymmetric-body delta wing model on which the wing vertical location on the body was systematically varied from low- to high-mounted positions. In addition, for two of these positions both horizontal and radial wing angular orientations relative to the body were tested, and roll angle effects were investigated for one of the positions. Seven different wing-body configurations and a body-alone configuration were studied. The test was conducted at Mach numbers from 1.70 to 2.86 at angles of attack from about -4 deg to 24 deg. Pressure orifices were located at three longitudinal stations on each wing-body model, and at each station the orifices were located completely around the body, along the lower surface of the right wing (looking upstream), and along the upper surface of the left wing. All pressure coefficient data are tabulated and selected samples are shown graphically to illustrate the effects of the test variables. The effects of angle of attack, roll angle, Mach number, longitudinal station, wing vertical location, wing angular orientation, and wing-body juncture are analyzed. The vertical location of the wing on the body had a very strong effect on the body pressures. For a given angle of attack at a roll angle of 0 deg, the pressures were virtually constant in the spanwise direction across the windward surfaces of the wing-body combination. Pressure-relieving, channeling, and vortex effects were noted in the data

    QUANTIFYING GAINS TO RISK DIVERSIFICATION USING CERTAINTY EQUIVALENCE IN A MEAN-VARIANCE MODEL: AN APPLICATION TO FLORIDA CITRUS

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    The marginal benefit and cost of diversification for Florida orange producers is analyzed using certainty equivalents. Results indicate that for moderate and high levels of risk aversion, diversification into strawberry, grapefruit, or additional orange production is not optimal. However, moderately risk averse Florida orange producers can gain by diversifying into grapefruit production if the annual amortized fixed costs can be reduced by as little as 10 percent.Risk and Uncertainty,

    Impact of Government Payments, Depreciation and Inflation on Investment Behavior in American Agriculture Sector Using Sample of Kansas Farms

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    A farm’s physical investment is affected by its fundamental q and by its financial situation, with the later comprising both the firm’s liquidity and its possibility of facing capital market imperfections. This study determines the effects of government payments, depreciation, and inflation on crop farm machinery and equipment investment behavior employing the Nonlinear Generalized Method of Moment (GMM) estimator to estimate the investment system. The magnitude of the lagged cash flows such as government payments, cash crop income, and grain income were largely responsible for determining farm investment behavior in the Kansas agriculture sector. An increase in lagged machinery and equipment depreciation and lagged farm motor vehicle and listed property depreciation increases total crop farm investment substantially for an average farm. Statistically, there is no evidence of inflation affects on crop farm machinery investment behavior.Investment, Liquidity, fundamental q, government payments, depreciation, inflation, Agribusiness, Agricultural Finance, Crop Production/Industries, Farm Management, Financial Economics, Livestock Production/Industries, Production Economics,

    Gravity enhanced acoustic levitation method and apparatus

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    An acoustic levitation system is provided for acoustically levitating an object by applying a single frequency from a transducer into a resonant chamber surrounding the object. The chamber includes a stabilizer location along its height, where the side walls of the chamber are angled so they converge in an upward direction. When an acoustic standing wave pattern is applied between the top and bottom of the chamber, a levitation surface within the stabilizer does not lie on a horizontal plane, but instead is curved with a lowermost portion near the vertical axis of the chamber. As a result, an acoustically levitated object is urged by gravity towards the lowermost location on the levitation surface, so the object is kept away from the side walls of the chamber

    Operation LION - Report for period of the flight of Apollo 11

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    Observations by Lunar International Observers Network and astronauts of lunar phenomena during Apollo 11 fligh

    Self-referential Monte Carlo method for calculating the free energy of crystalline solids

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    A self-referential Monte Carlo method is described for calculating the free energy of crystalline solids. All Monte Carlo methods for the free energy of classical crystalline solids calculate the free-energy difference between a state whose free energy can be calculated relatively easily and the state of interest. Previously published methods employ either a simple model crystal, such as the Einstein crystal, or a fluid as the reference state. The self-referential method employs a radically different reference state; it is the crystalline solid of interest but with a different number of unit cells. So it calculates the free-energy difference between two crystals, differing only in their size. The aim of this work is to demonstrate this approach by application to some simple systems, namely, the face centered cubic hard sphere and Lennard-Jones crystals. However, it can potentially be applied to arbitrary crystals in both bulk and confined environments, and ultimately it could also be very efficient
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