5,163 research outputs found

    ANALYSIS OF RECENT OPTIONS FOR CHANGES IN U.S. DAIRY POLICY

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    Agricultural and Food Policy,

    Development of improved-durability plasma sprayed ceramic coatings for gas turbine engines

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    As part of a NASA program to reduce fuel consumption of current commercial aircraft engines, methods were investigated for improving the durability of plasma sprayed ceramic coatings for use on vane platforms in the JT9D turbofan engine. Increased durability concepts under evaluation include use of improved strain tolerant microstructures and control of the substrate temperature during coating application. Initial burner rig tests conducted at temperatures of 1010 C (1850 F) indicate that improvements in cyclic life greater than 20:1 over previous ceramic coating systems were achieved. Three plasma sprayed coating systems applied to first stage vane platforms in the high pressure turbine were subjected to a 100-cycle JT9D engine endurance test with only minor damage occurring to the coatings

    The Canadian Harp Seal Hunt: A Moral Assessment

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    Sumner is a philosopher who attempts to unpick the various issues in the debate over the Harp Seal hunt in Canada. An objective treatment of the issues underlying the harp seal hunt is complex because of the high level of emotion on both sides, but it is also necessary to attempt it if uncommitted and reasonable persons are to be provided with some guidance about what to think concerning the morality of the hunt

    Post-Retirement Adjustments of Pension Benefits

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    This paper examines why pension plans increased their liabflities by giving benefit increases to persons no longer working even though almost al lof them were not required to do so by any legally enforceable contract. In our model workers and firms have implicit contracts under which post-retirement increases in benefits are purchased by workers through lower wages or initial benefits. Such arrangements permit both plans and workersto share the risk of uncertain rates of return. They also allow beneficiaries to invest at a higher net rate of return than they could obtain elsewhere because of tax advantages and, in large plans, economies of scale. We also discuss how post-retirement adjustments can be used to influence turnover. Some empirical implications of the model are tested over a sample of beneficiaries of defined benefit plans. The major empirical findings are:(1) There is strong evidence of compensating differentials in final salary and initial pension benefits for beneficiaries receiving post-retirement adjustments.(2) Regardless of how the size of pension plans is measured(beneficiaries, participants, amount of benefits paid), large pension plans provide larger post-retirement benefit increases.(3) Beneficiaries of collectively bargained plans are more likelyto receive benefit increases and, among those receiving benefit increases, receive larger increases.(4) Benefit increases are larger in percentage terms for those who have been retired the longest and for those with the most years of service.

    Division of labour and risk taking in the dinosaur ant, Dinoponera quadriceps

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    The success of social insects can be largely attributed to division of labour. In contrast to most social insects, many species with simple societies contain workers which are capable of sexual reproduction. Headed by one or a few reproductive individuals, subordinate workers form a dominance hierarchy, queuing to attain the reproductive role. In these species task allocation may be influenced by individual choice based on future reproductive prospects. Individuals with a better chance of inheriting the colony may be less likely to take risks and high-ranking workers that spend a greater amount of time in proximity to the brood may be able to increase the ability to police egg-laying by cheating subordinates. We investigated division of labour and risk taking in relation to dominance rank in the queenless ponerine ant, Dinoponera quadriceps, a species with relatively simple societies. Using behavioural observations, we show that high-ranking workers spend more time performing egg care, less time foraging and are less likely to defend the nest against attack. High-rankers also spent a greater amount of time guarding and inspecting eggs, behaviours which are likely to improve detection of egg laying by cheating subordinates. We also show that high-ranking workers spend a greater amount of time idle, which may help increase lifespan by reducing energy expenditure. Our results suggest that both risk-taking and egg-care behaviours are related to future reproductive prospects in D. quadriceps. This highlights a mechanism by which effective division of labour could have been achieved during the early stages of eusocial evolution

    The Impact of Nuclear Reaction Rate Uncertainties on Evolutionary Studies of the Nova Outburst

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    The observable consequences of a nova outburst depend sensitively on the details of the thermonuclear runaway which initiates the outburst. One of the more important sources of uncertainty is the nuclear reaction data used as input for the evolutionary calculations. A recent paper by Starrfield, Truran, Wiescher, & Sparks (1998) has demonstrated that changes in the reaction rate library used within a nova simulation have significant effects, not just on the production of individual isotopes (which can change by an order of magnitude), but on global observables such as the peak luminosity and the amount of mass ejected. We present preliminary results of systematic analyses of the impact of reaction rate uncertainties on nova nucleosynthesis.Comment: 4 pages, 3 figures. to appear in "Cosmic Explosions", proceeding of the 10th Annual October Astrophysics Conference in Maryland (ed. S.S. Holt and W. W. Zhang

    Emotional and behavioural problems in children with Developmental Coordination Disorder: Exploring parent and teacher reports

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    BACKGROUND: Although characterised by motor impairments, children with Developmental Coordination Disorder (DCD) also show high rates of psychopathology (anxiety, depression, low self-esteem). Such findings have led to calls for the screening of mental health problems in this group. AIMS: To investigate patterns and profiles of emotional and behavioural problems in children with and without DCD, using the Strengths and Difficulties Questionnaire (SDQ). METHODS AND PROCEDURES: Teachers and parents completed SDQs for 30 children with DCD (7-10 years). Teacher ratings on the SDQ were also obtained from two typically-developing (TD) groups: 35 children matched for chronological age, and 29 younger children (4-7 years) matched by motor ability. OUTCOMES AND RESULTS: Group and individual analyses compared parent and teacher SDQ scores for children with DCD. Teacher reports showed that children with DCD displayed higher rates of emotional and behavioural problems (overall, and on each subscale of the SDQ) relative to their TD peers. No differences were observed between the two TD groups. Inspection of individual data points highlighted variability in the SDQ scores of the DCD group (across both teacher and parent ratings), with suggestions of elevated hyperactivity but comparably lower levels of conduct problems across this sample. Modest agreement was found between teacher and parent ratings of children with DCD on the SDQ. CONCLUSIONS AND IMPLICATIONS: There is a need to monitor levels of emotional and behavioural problems in children with DCD, from multiple informants

    Geologic factors in the evaluation of water pollution potential at mountain dwelling sites

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    December, 1973.Bibliography: pages [133]-135.In order to establish the relationship between the geologic setting and the occurrence of water pollution in mountain home developments containing individual sewage disposal systems, three areas in Colorado's Front Range were studied. Two of the areas were known to have biological contamination as confirmed by microbiological tests. Also, each area had adequate rock exposures to allow for detailed geologic study, the absence of thick soil profiles above bedrock and current development for mountain home location. In addition, each of the selected study areas differed in geologic setting, age of development and home density in the development. The extent of water pollution was established by a program of well and surface water testing for total coliform. Fecal coliform and inorganic contaminants were tested in selected wells. Detailed geologic maps were made of each area to locate features such as dikes or shear zones which might act as either barriers or conduits to ground water movement. Slope maps were prepared for the area by computer plots of digitized data of elevations taken from U.S. Geological Survey topographic maps. Determination of the water table profile and extent of alluvial fill in valley bottoms was accomplished using driller's well logs for each well in the area. In addition, soils were tested to determine their effective grain size, a joint and foliation study was conducted to determine the direction of pollutant travel should effluent enter these openings, driller's well logs were used to establish depth of soils and depth of weathering in bedrock and data from county health records were used to establish soil percolation rates. Data were compiled in the form of overlays on base maps of the areas involved. A topographic map with the geologic overlay was used in conjunction with various combinations of the field derivative overlays to indicate the pollution potential for specific areas. The overlays used in this procedure were compiled from. the following parameters: 1) slope, 2) depth of soil, 3) depth of intensely weathered bedrock, 4) local water table profile, and 5) soil percolation rates. These overlays indicated that the Glen Haven area is unsuitable for soil absorption sewage systems because of steep slopes, soil depth and depth of the water table. Most of the Tall Timbers area was indicated as unsuitable for soil absorption systems because of slope, soil depth and local geology. The Crescent Park area was categorized as safe (in part) for soil absorption systems, however, local areas within the subdivision were categorized as hazardous. From the results it was suggested that a procedure such as the one used in this study could be used for each subdivision proposed in the mountainous regions of Colorado. Thus more effective use of mountainous areas might be passable while maintaining a low probability of ground water contamination. Areas within each proposed subdivision would be classified as safe, hazardous, or unsuitable for soil absorption sewage systems. Unsuitable areas could be used as parks or greenbelts, hazardous areas would have low population densities and safe areas would be allowed to have higher population densities as long as other factors were favorable. In addition, procedures such as the one used in this investigation could be used to indicate mountain areas which should require a municipal sewage disposal system before development to ensure that the ground water system was not polluted.Supported by the Colorado Water Quality Control Commission and the United States Department of Interior, Office of Water Resources Research, no.87-194-2. (s) 14-01-001-1882
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