4,890 research outputs found

    A BIO-ECONOMIC MODEL OF WETLAND PROTECTION ON PRIVATE LANDS

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    Wetland ecosystems on privately owned farms such as those on the Murrumbidgee River Floodplain in the state of New South Wales, Australia provide a mix of potentially valuable outputs to their owners and the wider community. The mix of values generated is dependent on the biophysical status of the wetlands, which in-turn, is dependent on the land management in and around these multiple-output ecosystems. Despite the range of private and public values generated, management decisions are based primarily on the private values that landowners receive. These private land management decisions also affect social values. Hence, there is potentially a demand for public policy to influence decisions based on the social values wetlands generate. This paper is predicated on the principle that good policy is reliant on information about wetland values. We present an integrated bio-economic model of wetland management that incorporates the biological and economic impacts at a landscape scale. The model reflects the multiple private and social values generated by wetlands and the dynamic nature of the trade-offs between these values. A number of broad policy conclusions for wetland management in Australia are generated from the outputs of the bio-economic model.Land Economics/Use,

    Future thinking on carved stones

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    The solutions to an infinite family of matrix inequalities involving ZME-matrices

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    AbstractSolutions for a certain infinite system of matrix inequalities are determined. In these inequalities, the coefficient matrices are ZME-matrices, which were introduced by Friedland, Hershkowitz, and Schneider. The solutions are shown to have a simple form under certain restrictions on the magnitudes of the minimal eigenvalues of the coefficient matrices. Finally, solutions to the system of inequalities are used to study the structure of reducible ZM-matrices

    Parental presence prior to surgery and the emotional status of the child on arrival in the operating suite: a study of 144 cases.

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    Theoretical and experimental studies of molecular motions and reaction mechanisms

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    The time-delayed forwards scattering mechanism recently observed by Althorpe et al. [1] for the H + D2 (v=O, j=O) --? HD(v'=3, j'=O) + D reaction was analysed using the quasi-classical trajectory (QCT) methodology. QCT's were found to reasonably match the quantum snapshots of Althorpe, without the quantum effects. Trajectories were analysed on the fly to investigate the motions of the atoms during the reaction. The dominant reaction mechanism progresses from hard collinear impacts, leading to direct recoil, to glancing impacts. The increased time required for forward scattered trajectories is due to the rotation of the HDD complex. Forwards scattered trajectories display symmetric stretch vibrations of the HDD complex, indicating the presence of a resonance or a quantum bottleneck state. Reactive scattering in the HD(v'=O, j'=O) product channel was found to be governed by two unexpected and dominant new mechanisms, and not by direct recoil as is generally assumed. The new mechanisms involve strong interaction with the conical intersection, an area of the potential energy surface not previously thought to have much effect upon reactive scattering. Initial investigations indicate up to 56% of reactive scattering could be the result of these mechanisms.UV Cavity Ring-Down Spectroscopy of 1, 4-bis(phenylethynyl}benzene The torsional motion of 1, 4 bis(phenylethynyl)benzene (BPEB), a prototype molecular wire, is important for switching in molecular electronics. Cavity ring-down spectroscopy was used to record the torsional spectra of BPEB and 1, 4-bis(phenylethynyl) 2,3,5,6-tetradeuterobenzene in the gas phase. The spectra were modelled using a simple cosine potential. The experimental torsional barrier is very similar to the two ring system, Tolane. It was found that DFT calculations completely overestimate the torsional barrier.I

    Apodized vortex coronagraph designs for segmented aperture telescopes

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    Current state-of-the-art high contrast imaging instruments take advantage of a number of elegant coronagraph designs to suppress starlight and image nearby faint objects, such as exoplanets and circumstellar disks. The ideal performance and complexity of the optical systems depends strongly on the shape of the telescope aperture. Unfortunately, large primary mirrors tend to be segmented and have various obstructions, which limit the performance of most conventional coronagraph designs. We present a new family of vortex coronagraphs with numerically-optimized gray-scale apodizers that provide the sensitivity needed to directly image faint exoplanets with large, segmented aperture telescopes, including the Thirty Meter Telescope (TMT) as well as potential next-generation space telescopes.Comment: To appear in SPIE proceedings vol. 991

    Segmented coronagraph design and analysis (SCDA): an initial design study of apodized vortex coronagraphs

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    The segmented coronagraph design and analysis (SCDA) study is a coordinated effort, led by Stuart Shaklan (JPL) and supported by NASA's Exoplanet Exploration Program (ExEP), to provide efficient coronagraph design concepts for exoplanet imaging with future segmented aperture space telescopes. This document serves as an update on the apodized vortex coronagraph designs devised by the Caltech/JPL SCDA team. Apodized vortex coronagraphs come in two flavors, where the apodization is achieved either by use of 1) a gray-scale semi-transparent pupil mask or 2) a pair of deformable mirrors in series. Each approach has attractive benefits. This document presents a comprehensive review of the former type. Future theoretical investigations will further explore the use of deformable mirrors for apodization.Comment: White Paper (2016-2017
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