22,399 research outputs found

    Detection of molecular microwave transitions in the 3 mm wavelength range in comet Kohoutek (1973f)

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    Observations of comet Kohoutek made with a 3-mm line receiver mounted on the 11-m NRAO radio dish at Kitt Peak are presented. The detection of line transitions of hydrogen cyanide and methyl cyanide is reported and discussed along with the variability of neutral gas jets. Microwave transitions in molecules of cometary origin are also examined

    Private Options to Use Public Goods Exploiting Revealed Preferences to Estimate Environmental Benefits

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    We develop and apply a new method for estimating the economic benefits of an environmental amenity. The method fits within the household production framework (Becker 1965), and is based upon the notion of estimating the derived demand for a privately traded option to utilize a freely-available public good. In particular, the demand for state fishing licenses is used to infer the benefits of recreational fishing. Using panel data on state fishing license sales and prices for the continental United States over a fifteen-year period, combined with data on substitute prices and demographic variables, a license demand function is estimated with instrumental variable procedures to allow for the potential endogeneity of administered prices. The econometric results lead to estimates of the benefits of a fishing license, and subsequently to the expected benefits of a recreational fishing day. In contrast with previous studies, which have utilized travel cost or hypothetical market methods, our approach provides estimates that are directly comparable across geographic areas. Further, our results suggest that the benefits of recreational fishing days are generally less than previously estimated.Private Options, Public Goods, Environmental Benefits

    Conceptual design of single turbofan engine powered light aircraft

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    The conceptual design of a four place single turbofan engine powered light aircraft was accomplished utilizing contemporary light aircraft conventional design techniques as a means of evaluating the NASA-Ames General Aviation Synthesis Program (GASP) as a preliminary design tool. In certain areas, disagreement or exclusion were found to exist between the results of the conventional design and GASP processes. Detail discussion of these points along with the associated contemporary design methodology are presented

    Plastic Flowage of Salt in Mines at Hutchinson and Lyons, Kansas

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    Plastic flowage in the pillars and floors of salt mines at Hutchinson and Lyons, Kansas, is indicated by buckling, spalling, and fracturing. Detailed measurements of the relative size of the pillars in newly opened rooms and crosscuts were made over a period of 11 months. These data indicate that the salt flowage is due to pressure of the overburden and is controlled by the volume of salt excavated and configuration of the excavation. Plastic flowage causes folds and fractures to develop only in the floor of the Lyons mine. The orientation of structures and rates of flowage in the base, top, and middle of pillars are governed by the direction of easiest relief of stress, which is controlled by the mining plan

    Plastic Flowage of Salt in Mines at Hutchinson and Lyons, Kansas

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    Plastic flowage in the pillars and floors of salt mines at Hutchinson and Lyons, Kansas, is indicated by buckling, spalling, and fracturing. Detailed measurements of the relative size of the pillars in newly opened rooms and crosscuts were made over a period of 11 months. These data indicate that the salt flowage is due to pressure of the overburden and is controlled by the volume of salt excavated and configuration of the excavation. Plastic flowage causes folds and fractures to develop only in the floor of the Lyons mine. The orientation of structures and rates of flowage in the base, top, and middle of pillars are governed by the direction of easiest relief of stress, which is controlled by the mining plan

    The Hudson Bay Lithospheric Experiment (HuBLE) : Insights into Precambrian Plate Tectonics and the Development of Mantle Keels

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    The UK component of HuBLE was supported by Natural Environment Research Council (NERC) grant NE/F007337/1, with financial and logistical support from the Geological Survey of Canada, Canada–Nunavut Geoscience Office, SEIS-UK (the seismic node of NERC), and First Nations communities of Nunavut. J. Beauchesne and J. Kendall provided invaluable assistance in the field. Discussions with M. St-Onge, T. Skulski, D. Corrigan and M. Sanborne-Barrie were helpful for interpretation of the data. D. Eaton and F. A. Darbyshire acknowledge the Natural Sciences and Engineering Research Council. Four stations on the Belcher Islands and northern Quebec were installed by the University of Western Ontario and funded through a grant to D. Eaton (UWO Academic Development Fund). I. Bastow is funded by the Leverhulme Trust. This is Natural Resources Canada Contribution 20130084 to its Geomapping for Energy and Minerals Program. This work has received funding from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement no. 240473 ‘CoMITAC’.Peer reviewedPublisher PD

    Some comments on the universal constant in DSR

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    Deformed Special Relativity is usually presented as a deformation of Special Relativity accommodating a new universal constant, the Planck mass, while respecting the relativity principle. In order to avoid some fundamental problems (e.g. soccer ball problem), we argue that we should switch point of view and consider instead the Newton constant GG as the universal constant.Comment: 12 pages, Proceedings of DICE2006 (Piombino, Italy

    Hartree-Fock-Bogoliubov Model and Simulation of Attractive and Repulsive Bose-Einstein Condensates

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    We describe a model of dynamic Bose-Einstein condensates near a Feshbach resonance that is computationally feasible under assumptions of spherical or cylindrical symmetry. Simulations in spherical symmetry approximate the experimentally measured time to collapse of an unstably attractive condensate only when the molecular binding energy in the model is correct, demonstrating that the quantum fluctuations and atom-molecule pairing included in the model are the dominant mechanisms during collapse. Simulations of condensates with repulsive interactions find some quantitative disagreement, suggesting that pairing and quantum fluctuations are not the only significant factors for condensate loss or burst formation. Inclusion of three-body recombination was found to be inconsequential in all of our simulations, though we do not consider recent experiments [1] conducted at higher densities

    Effect of an atom on a quantum guided field in a weakly driven fiber-Bragg-grating cavity

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    We study the interaction of an atom with a quantum guided field in a weakly driven fiber-Bragg-grating (FBG) cavity. We present an effective Hamiltonian and derive the density-matrix equations for the combined atom-cavity system. We calculate the mean photon number, the second-order photon correlation function, and the atomic excited-state population. We show that, due to the confinement of the guided cavity field in the fiber cross-section plane and in the space between the FBG mirrors, the presence of the atom in the FBG cavity can significantly affect the mean photon number and the photon statistics even though the cavity finesse is moderate, the cavity is long, and the probe field is weak.Comment: Accepted for Phys. Rev.
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