45,270 research outputs found

    Resolvable designs with large blocks

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    Resolvable designs with two blocks per replicate are studied from an optimality perspective. Because in practice the number of replicates is typically less than the number of treatments, arguments can be based on the dual of the information matrix and consequently given in terms of block concurrences. Equalizing block concurrences for given block sizes is often, but not always, the best strategy. Sufficient conditions are established for various strong optimalities and a detailed study of E-optimality is offered, including a characterization of the E-optimal class. Optimal designs are found to correspond to balanced arrays and an affine-like generalization.Comment: Published at http://dx.doi.org/10.1214/009053606000001253 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Statistical analysis of time transfer data from Timation 2

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    Between July 1973 and January 1974, three time transfer experiments using the Timation 2 satellite were conducted to measure time differences between the U.S. Naval Observatory and Australia. Statistical tests showed that the results are unaffected by the satellite's position with respect to the sunrise/sunset line or by its closest approach azimuth at the Australian station. Further tests revealed that forward predictions of time scale differences, based on the measurements, can be made with high confidence

    Market scenarios and alternative administrative frameworks for US educational satellite systems

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    Costs and benefits of developing an operational educational satellite system in the U.S. are analyzed. Scenarios are developed for each educational submarket and satellite channel and ground terminal requirements for a large-scale educational telecommunications system are estimated. Alternative organizational frameworks for such a system are described

    An economic evaluation of the osmoregulation gene technology to the Australian wheat industry

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    Episodes of rainfall irregularity and soil moisture deficit have focused attention on the widespread limitation of water supply on winter cereal crop production in Australia. This has motivated a number of efforts at breeding for improved drought tolerance. A recent example involves a cellular adaptation which mitigates water loss through solute accumulation (osmoregulation or osmotic adjustment). An assessment of the performance of osmoregulation yield response in the presence of climate change found that wheat cultivars with this gene are unlikely to be adversely affected by hotter and drier conditions across the wheat belt. The results of an economic evaluation of potential future innovations (wheat cultivars) from the osmoregulation gene technology are that for Australia the net present value could range from 388millionto388 million to 3.6 billion, depending on the adoption of wheat cultivars with the gene. Associated benefit-cost ratios ranged from 43:1 to 390:1, and internal rates of return were 16% to 27%. Even under pessimistic assumptions the returns are quite healthy. For NSW-only adoption, internal rates of return ranged from 10% to 22%. This osmoregulation technology has the potential for inclusion in wheat cultivars bred for other purposes, and for other crops. As such it has implications for agricultural plant breeders and farmers both in Australia and overseas, and there are substantial potential spillover benefits.economic evaluation, wheat breeding, osmoregulation, Crop Production/Industries, Research Methods/ Statistical Methods,

    Large-scale educational telecommunications systems for the US: An analysis of educational needs and technological opportunities

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    The needs to be served, the subsectors in which the system might be used, the technology employed, and the prospects for future utilization of an educational telecommunications delivery system are described and analyzed. Educational subsectors are analyzed with emphasis on the current status and trends within each subsector. Issues which affect future development, and prospects for future use of media, technology, and large-scale electronic delivery within each subsector are included. Information on technology utilization is presented. Educational telecommunications services are identified and grouped into categories: public television and radio, instructional television, computer aided instruction, computer resource sharing, and information resource sharing. Technology based services, their current utilization, and factors which affect future development are stressed. The role of communications satellites in providing these services is discussed. Efforts to analyze and estimate future utilization of large-scale educational telecommunications are summarized. Factors which affect future utilization are identified. Conclusions are presented

    Quality of life and building design in residential and nursing homes for older people

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    Older people living in residential and nursing care homes spend a large proportion of their time within the boundaries of the home, and may depend on the environment to compensate for their physical or cognitive frailties. Regulations and guidelines on the design of care buildings have accumulated over time with little knowledge of their impact on the quality of life of building users. The Design in Caring Environments Study (DICE) collected cross-sectional data on building design and quality of life in 38 care homes in and near Sheffield, Yorkshire. Quality of life was assessed using methods which included all residents regardless of their frailty, and staff morale was also assessed. The physical environment was measured on 11 user-related domains using a new tool, the Sheffield Care Environment Assessment Matrix (SCEAM). Significant positive associations were found between several aspects of the built environment and the residents' quality of life. There was evidence that a focus on safety and health requirements could be creating risk-averse environments which act against quality of life, particularly for the least frail residents. Staff morale was associated with attributes of a non-institutional environment for residents rather than with the facilities provided for the staff. The new tool for assessing building design has potential applications in further research and for care providers
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