4,966 research outputs found

    Combining remotely sensed and other measurements for hydrologic areal averages

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    A method is described for combining measurements of hydrologic variables of various sampling geometries and measurement accuracies to produce an estimated mean areal value over a watershed and a measure of the accuracy of the mean areal value. The method provides a means to integrate measurements from conventional hydrological networks and remote sensing. The resulting areal averages can be used to enhance a wide variety of hydrological applications including basin modeling. The correlation area method assigns weights to each available measurement (point, line, or areal) based on the area of the basin most accurately represented by the measurement. The statistical characteristics of the accuracy of the various measurement technologies and of the random fields of the hydrologic variables used in the study (water equivalent of the snow cover and soil moisture) required to implement the method are discussed

    Strategies for using remotely sensed data in hydrologic models

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    Present and planned remote sensing capabilities were evaluated. The usefulness of six remote sensing capabilities (soil moisture, land cover, impervious area, areal extent of snow cover, areal extent of frozen ground, and water equivalent of the snow cover) with seven hydrologic models (API, CREAMS, NWSRFS, STORM, STANFORD, SSARR, and NWSRFS Snowmelt) were reviewed. The results indicate remote sensing information has only limited value for use with the hydrologic models in their present form. With minor modifications to the models the usefulness would be enhanced. Specific recommendations are made for incorporating snow covered area measurements in the NWSRFS Snowmelt model. Recommendations are also made for incorporating soil moisture measurements in NWSRFS. Suggestions are made for incorporating snow covered area, soil moisture, and others in STORM and SSARR. General characteristics of a hydrologic model needed to make maximum use of remotely sensed data are discussed. Suggested goals for improvements in remote sensing for use in models are also established

    Spectrum, Winter 1992

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    Spectrum was a newsletter for students, faculty, staff and alumni of the Henry M. Goldman School of Dental Medicine, published from 1983-1992

    Monitoring the Bi-Directional Relativistic Jets of the Radio Galaxy 1946+708

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    We report on a multi-frequency, multi-epoch campaign of Very Long Baseline Interferometry observations of the radio galaxy 1946+708 using the VLBA and a Global VLBI array. From these high-resolution observations we deduce the kinematic age of the radio source to be ∌\sim4000 years, comparable with the ages of other Compact Symmetric Objects (CSOs). Ejections of pairs of jet components appears to take place on time scales of 10 years and these components in the jet travel outward at intrinsic velocities between 0.6 and 0.9 c. From the constraint that jet components cannot have intrinsic velocities faster than light, we derive H_0 > 57 km s^-1 Mpc^-1 from the fastest pair of components launched from the core. We provide strong evidence for the ejection of a new pair of components in ~1997. From the trajectories of the jet components we deduce that the jet is most likely to be helically confined, rather than purely ballistic in nature.Comment: 20 pages, 8 figures, accepted to Ap

    Welcome To Our Heroes

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    https://digitalcommons.library.umaine.edu/mmb-vp/5350/thumbnail.jp

    Thinking beyond the hybrid:“actually-existing” cities “after neoliberalism” in Boyle <i>et al.</i>

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    In their article, ‘The spatialities of actually existing neoliberalism in Glasgow, 1977 to present’, Mark Boyle, Christopher McWilliams and Gareth Rice (2008) usefully problematise our current understanding of neoliberal urbanism. Our response is aimed at developing a sympathetic but critical approach to Boyle et al's understanding of neoliberal urbanism as illustrated by the Glasgow example. In particular, the counterposing by Boyle et al of a 'hybrid, mutant' model to a 'pure' model of neoliberalism for us misrepresents existing models of neoliberalism as a perfectly finished object rather than a roughly mottled process. That they do not identify any ‘pure’ model leads them to create a straw construct against which they can claim a more sophisticated, refined approach to the messiness of neoliberal urbanism. In contrast, we view neoliberalism as a contested and unstable response to accumulation crises at various scales of analysis

    Obscuration of the Parsec Scale Jets in the Compact Symmetric Object 1946+708

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    We present results of VLA and VLBA observations of the 1.420 GHz neutral hydrogen absorption associated with the Compact Symmetric Object 1946+708 (z=0.101). We find significant structure in the gas on parsec scales. The peak column density in the HI (N_HI~2.2x10^23 cm^-2 (T_s/8000K)) occurs toward the center of activity of the source, as does the highest velocity dispersion (FWHM~350 \kms). In addition, we find that the continuum spectra of the various radio components associated with these jets strongly indicate free-free absorption. This effect is particularly pronounced toward the core and inner components of the receding jet, suggesting the presence of a screen local to the source, perhaps part of an obscuring torus.Comment: revised version, some text added, 1 figure changed; accepted to Astrophysical Journal, 22 page LaTeX document includes 8 postscript figure
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