4,459 research outputs found

    Sound Scholarship: Scope, Purpose, Function and Potential of Phonorecord Archives

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    Environmental management in development : the evolution of paradigms

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    In the past quarter century, environmental management has increasingly become a concern of governments. More recently, the traditional split between developers and conservationists has begun to break down. Conceptions of what is economically and technologically practical, ecologically necessary, and politically feasible are rapidly changing. This report discusses the implications of five paradigms of environmental management in development. The author notes that the remedial legalistic approach of environmental management is breaking down. Instead, interest in the more economically integrated approach of resource management has recently taken hold. Several interdependent forces indicate that improving the economic management of pollution and resources may be a necessary but insufficient measure to create the conditions for sustainable development. The perception of tradeoffs between development and environmental quality persists in the present debate, but its necessity is greatly exaggerated, according to this paper. Finally, it is noted that paradigms may be impervious to evidence, and institutions and societies too difficult to change. Whether, when and how these issues are resolved may be modern civilization's most significant test.Environmental Economics&Policies,Agricultural Knowledge&Information Systems,Health Monitoring&Evaluation,Natural Resources Management,Agricultural Research

    Amorphous interface layer in thin graphite films grown on the carbon face of SiC

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    Cross-sectional transmission electron microscopy (TEM) is used to characterize an amorphous layer observed at the interface in graphite and graphene films grown via thermal decomposition of C-face 4H-SiC. The amorphous layer does not to cover the entire interface, but uniform contiguous regions span microns of cross-sectional interface. Annular dark field scanning transmission electron microscopy (ADF-STEM) images and electron energy loss spectroscopy (EELS) demonstrate that the amorphous layer is a carbon-rich composition of Si/C. The amorphous layer is clearly observed in samples grown at 1600{\deg}C for a range of growth pressures in argon, but not at 1500{\deg}C, suggesting a temperature-dependent formation mechanism

    Valuing Private and Public Greenspace Using Remotely Sensed Vegetation Indices

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    In a typical metropolitan area, greenspace varies substantially in its quality and extent. Remotely sensed vegetation index data is used to characterize the heterogeneity in private and public greenspace (riparian corridors) in metropolitan Tucson, Arizona. This data set enables the researcher to test if: (1) greenness is a significant determinant of house price variation in this desert city; and (2) whether there is an interaction between public and private greenspace. Private greenspace amenities can be endogenously improved by homeowners as a complement or substitute for the greenspace that is publicly provided, whereas public greenspace might be exogenous or endogenous depending on households ability to pressure the local government to protect or restore public greenspace. The results of a Hausman test indicate that endogeneity is a problem in the dataset and therefore an instrumental variable two stage least squares estimation is used. The results of this analysis indicate that homebuyers in the study area have preferences for both greener lots and greener riparian corridors and that private and public greenspace appear to be substitutes. Results are robust across multiple identification strategies designed to address potential endogeneity. The study results could have fundamental implications for the efficient use of limited water supplies in this semi-arid metropolitan area.Resource /Energy Economics and Policy,

    How Do Homebuyers Value Different Types of Green Space?

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    It is important to understand tradeoffs in preferences for natural and constructed green space in semi-arid urban areas because these lands compete for scarce water resources. We perform a hedonic study using high resolution, remotely-sensed vegetation indices and house sales records. We find that homebuyers in the study area prefer greener lots, greener neighborhoods, and greener nearby riparian corridors, and they pay premiums for proximity to green space amenities. The findings have fundamental implications for the efficient allocation of limited water supplies between different types of green space and for native vegetation conservation in semi-arid metropolitan areas.hedonic model, locally weighted regression, spatial, open space, golf course, park, riparian, Consumer/Household Economics, Land Economics/Use,

    Do Homebuyers Care about the 'Quality' of Natural Habitats?

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    We study if homebuyers in Tucson, Arizona care about the condition of natural habitats and if they have preferences between natural and manmade habitats. Using field work data we examine whether homebuyers willingness to pay is influenced by the biological condition of the neighboring riparian habitat and how homebuyers value alternative manmade green areas, specifically golf courses. We also explore the relationship between the field data and remote sensing vegetation indices. The results of a hedonic analysis of houses that sold within 0.2 miles of 51 stratified-random selected riparian survey sites in Tucson, Arizona reveals that homebuyers significantly value habitat quality and negatively value manmade park-like features. Homebuyers are willing to pay twenty percent more to live near a riparian corridor that is densely vegetated and contains more shrub and tree species, particularly species that are dependent on perennial water flow. These environmental premiums are significant, outweighing structural factors such as an additional garage or swimming pool. Likewise, proximity to a riparian habitat with low biological quality or to a golf course lowers property values.Land Economics/Use,

    Modal Noise Mitigation through Fiber Agitation for Fiber-fed Radial Velocity Spectrographs

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    Optical fiber modal noise is a limiting factor for high precision spectroscopy signal-to-noise in the near-infrared and visible. Unabated, especially when using highly coherent light sources for wavelength calibration, modal noise can induce radial velocity (RV) errors that hinder the discovery of low-mass (and potentially Earth-like) planets. Previous research in this field has found sufficient modal noise mitigation through the use of an integrating sphere, but this requires extremely bright light sources, a luxury not necessarily afforded by the next generation of high-resolution optical spectrographs. Otherwise, mechanical agitation, which "mixes" the fiber's modal patterns and allows the noise to be averaged over minutes-long exposures, provides some noise reduction but the exact mechanism behind improvement in signal-to-noise and RV drift has not been fully explored or optimized by the community. Therefore, we have filled out the parameter space of modal noise agitation techniques in order to better understand agitation's contribution to mitigating modal noise and to discover a better method for agitating fibers. We find that modal noise is best suppressed by the quasi-chaotic motion of two high-amplitude agitators oscillating with varying phase for fibers with large core diameters and low azimuthal symmetry. This work has subsequently influenced the design of a fiber agitator, to be installed with the EXtreme PREcision Spectrograph, that we estimate will reduce modal-noise-induced RV error to less than 3.2 cm/s.Comment: Accepted by The Astrophysical Journa
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