75,734 research outputs found

    Design of a video teleconference facility for a synchronous satellite communications link

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    The system requirements, design tradeoffs, and final design of a video teleconference facility are discussed, including proper lighting, graphics transmission, and picture aesthetics. Methods currently accepted in the television broadcast industry are used in the design. The unique problems associated with using an audio channel with a synchronous satellite communications link are discussed, and a final audio system design is presented

    Hierarchical models of very large problems, dilemmas, prospects, and an agenda for the future

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    Interdisciplinary approaches to the modeling of global problems are discussed in terms of multilevel cooperation. A multilevel regionalized model of the Lake Erie Basin is analyzed along with a multilevel regionalized world modeling project. Other topics discussed include: a stratified model of interacting region in a world system, and the application of the model to the world food crisis in south Asia. Recommended research for future development of integrated models is included

    Quantification of channel planform change on the lower Rangitikei River, New Zealand, 1949-2007: response to management?

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    The Rangitikei River, a large gravel‐bed wandering river located in the North Island of New Zealand, has outstanding scenic characteristics, recreational, fisheries and wildlife habitat features. Recently concerns have been raised over the potential negative impact that perceived channel changes in the latter part of the 20th century may be having on the Rangitikei River recreational fishery. This study describes and quantifies the large‐scale morphological changes that have occurred in selected reaches of the lower Rangitikei River between 1949 and 2007. This research utilised historical aerial photography and analysis in ArcGIS® to quantify channel planform change in three reaches, encompassing ~18 km of the lower Rangitikei River. This showed that the lower Rangitikei was transformed from a multi‐channelled planform to a predominantly single‐thread wandering planform, with an associated reduction in morphological complexity and active channel width of up to 74%, between 1949 and 2007. Bank protection measures instigated under the Rangitikei River Scheme have primarily driven these changes. Gravel extraction has also contributed by enhancing channel‐floodplain disconnection and exacerbating sediment deficits. The findings of this study have implications for future management of the Rangitikei. Previous lower Rangitikei River management schemes have taken a reach‐based engineering approach with a focus on bank erosion protection and flood mitigation. This study has confirmed the lower river has responded geomorphologically to these goals of river control. However questions as to the economic and ecological sustainability of this management style may encourage river managers to consider the benefits of promoting a self‐adjusting fluvial system within a catchment‐framed management approach

    ACE Bounds; SEMs with Equilibrium Conditions

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    Discussion of "Instrumental Variables: An Econometrician's Perspective" by Guido W. Imbens [arXiv:1410.0163].Comment: Published in at http://dx.doi.org/10.1214/14-STS485 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Smoking\u27s effect on hangover symptoms

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    Measuring Producer Level Beef Cattle Alliance Financial Performance

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    There has been a movement toward developing production and marketing alliances in the beef cattle sector in the United States to improve communications and ultimately provide higher priced branded products consistent with consumer demand. Beef cattle producers do not employ a consistent methodology to measure the financial performance of alliance participation. Nor do they have the information to negotiate financially sustainable agreements. The concentrated packer and retail sector do not share cost and returns information beyond total business data required by public traded corporations. A methodology using cost accounting and economic analysis is described to measure return on producer's assets for an alliance agreement. This information can be used to inform the margin sectors, feedyards, packers and retailers on what share of increased revenue from branded product sales to pass to the cow-calf segment to make participation competitive and the alliance financially sustainable. The cow-calf segment must absorb the added costs and cyclical financial loss to participate in alliances. Increased revenue is required to make branded products a more profitable marketing option than producing commodity beef.Agricultural Finance, Livestock Production/Industries,

    Economic Benefits of American Lobster Fishery Management Regulations

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    A simulation model is used to compare measures for future management identified in the American lobster fishery management plan; specifically, increases in the minimum legal size and a modest reduction in aggregate fishing mortality are evaluated. The analysis differs from previous work in that the distributional aspects of the alternative management regulations are quantified. The results indicate that (1) both an increased minimum size and a reduction in fishing mortality are economically justified in the sense that net benefits are positive; (2) increasing the minimum size without an adjunct regulation to prohibit entry will cause present fishermen to suffer an initial short-term reduction in revenues for which there will be no long-term gain; (3) because increased minimum size can be justified on the basis of consumer benefits alone, arguments favoring its increase to prevent recruitment failure are moot as far as a test of national economic efficiency is concerned; and (4) a program of effort reduction which reduces by 20% the fraction of available lobsters captured annually is projected to generate SI of producer benefits for every pound of lobster landed. Reducing the annual harvest fraction by 20% results in a level of fishery benefits greater than increasing the minimum size to 89 mm (3^-in.), and increases the coincidence of short-run costs and long-term benefits among those impacted by fishery management.Environmental Economics and Policy, Resource /Energy Economics and Policy,
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