15,570 research outputs found

    Exotic Forest Insects and Residential Property Values

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    This paper presents a case study of the economic damages to homeowners in a northern New Jersey community due to an exotic forest insect--the hemlock woolly adelgid. Hedonic property value methods are used to estimate the effect of hemlock health on property values. A statistically significant relationship between hemlock health and residential property values is established. Moreover, there are some signs of spillover impacts from hemlock decline, as negative effects are realized on the parcels where the declining hemlock stands are located as well as on neighboring properties. These results give some indication of the benefits of potential control programs and strategies and also show support for community- or neighborhood-based programs in residential settings.invasive species, economic impacts, hedonic property values, general spatial model, Land Economics/Use,

    Conservatism implications of shock test tailoring for multiple design environments

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    A method for analyzing shock conservation in test specifications that have been tailored to qualify a structure for multiple design environments is discussed. Shock test conservation is qualified for shock response spectra, shock intensity spectra and ranked peak acceleration data in terms of an Index of Conservation (IOC) and an Overtest Factor (OTF). The multi-environment conservation analysis addresses the issue of both absolute and average conservation. The method is demonstrated in a case where four laboratory tests have been specified to qualify a component which must survive seven different field environments. Final judgment of the tailored test specification is shown to require an understanding of the predominant failure modes of the test item

    An Alternative Accurate Tracer of Molecular Clouds: The "XCIX_{\rm CI}-Factor"

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    We explore the utility of CI as an alternative high-fidelity gas mass tracer for Galactic molecular clouds. We evaluate the XCI_{\rm CI}-factor for the 609 μ\mum carbon line, the analog of the CO X-factor, which is the ratio of the H2_2 column density to the integrated 12^{12}CO(1-0) line intensity. We use 3D-PDR to post-process hydrodynamic simulations of turbulent, star-forming clouds. We compare the emission of CI and CO for model clouds irradiated by 1 and 10 times the average background and demonstrate that CI is a comparable or superior tracer of the molecular gas distribution for column densities up to 6×10236 \times 10^{23} cm2^{-2}. Our results hold for both reduced and full chemical networks. For our fiducial Galactic cloud we derive an average XCOX_{\rm CO} of 3.0×10203.0\times 10^{20} cm2^{-2}K1^{-1}km1^{-1}s and XCIX_{\rm CI} of 1.1×10211.1\times 10^{21} cm2^{-2}K1^{-1}km1^{-1}s.Comment: 5 pages, 4 figures, 1 table, accepted to MNRAS Letter

    Phase and micromotion of Bose-Einstein condensates in a time-averaged ring trap

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    Rapidly scanning magnetic and optical dipole traps have been widely utilised to form time-averaged potentials for ultracold quantum gas experiments. Here we theoretically and experimentally characterise the dynamic properties of Bose-Einstein condensates in ring-shaped potentials that are formed by scanning an optical dipole beam in a circular trajectory. We find that unidirectional scanning leads to a non-trivial phase profile of the condensate that can be approximated analytically using the concept of phase imprinting. While the phase profile is not accessible through in-trap imaging, time-of-flight expansion manifests clear density signatures of an in-trap phase step in the condensate, coincident with the instantaneous position of the scanning beam. The phase step remains significant even when scanning the beam at frequencies two orders of magnitude larger than the characteristic frequency of the trap. We map out the phase and density properties of the condensate in the scanning trap, both experimentally and using numerical simulations, and find excellent agreement. Furthermore, we demonstrate that bidirectional scanning eliminated the phase gradient, rendering the system more suitable for coherent matter wave interferometry.Comment: 10 pages, 7 figure

    MAESTRO, CASTRO, and SEDONA -- Petascale Codes for Astrophysical Applications

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    Performing high-resolution, high-fidelity, three-dimensional simulations of Type Ia supernovae (SNe Ia) requires not only algorithms that accurately represent the correct physics, but also codes that effectively harness the resources of the most powerful supercomputers. We are developing a suite of codes that provide the capability to perform end-to-end simulations of SNe Ia, from the early convective phase leading up to ignition to the explosion phase in which deflagration/detonation waves explode the star to the computation of the light curves resulting from the explosion. In this paper we discuss these codes with an emphasis on the techniques needed to scale them to petascale architectures. We also demonstrate our ability to map data from a low Mach number formulation to a compressible solver.Comment: submitted to the Proceedings of the SciDAC 2010 meetin

    Lorentz transformations of open systems

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    We consider open dynamical systems, subject to external interventions by agents that are not completely described by the theory (classical or quantal). These interventions are localized in regions that are relatively spacelike. Under these circumstances, no relativistic transformation law exists that relates the descriptions of the physical system by observers in relative motion. Still, physical laws are the same in all Lorentz frames.Comment: Final version submitted to J. Mod. Opt. (Proc. of Gdansk conference

    Penobscot Valley Prudent Investment Linking Our Towns A Report on Education,Housing, and Capital Planning Opportunities

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    This report brings together three studies focusing on regional planning and public investment opportunities in the Greater Bangor area. These documents were completed as part of the Penobscot Valley Prudent Investments Linking Our Towns (PVPILOT) research project sponsored by the Eastern Maine Development Corporation and by the TCSP Pilot Program of the Federal Highway Administration. Our goal is to help advance the discussion of regional cooperative strategies in education, housing, and the provision of public services
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