1,300 research outputs found

    Space disposal of nuclear wastes. Volume 1: Socio-political aspects

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    The history and interpretation of radioactive waste management in the U.S., criteria for choosing from various options for waste disposal, and the impact of nuclear power growth from 1975 to 2000 are discussed. Preconditions for the existence of high level wastes in a form suitable for space disposal are explored. The role of the NASA space shuttle program in the space disposal of nuclear wastes, and the impact on program management, resources and regulation are examined

    Geostatistical evaluation of integrated marsh management impact on mosquito vectors using before-after-control-impact (BACI) design

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    <p>Abstract</p> <p>Background</p> <p>In many parts of the world, salt marshes play a key ecological role as the interface between the marine and the terrestrial environments. Salt marshes are also exceedingly important for public health as larval habitat for mosquitoes that are vectors of disease and significant biting pests. Although grid ditching and pesticides have been effective in salt marsh mosquito control, marsh degradation and other environmental considerations compel a different approach. Targeted habitat modification and biological control methods known as Open Marsh Water Management (OMWM) had been proposed as a viable alternative to marsh-wide physical alterations and chemical control. However, traditional larval sampling techniques may not adequately assess the impacts of marsh management on mosquito larvae. To assess the effectiveness of integrated OMWM and marsh restoration techniques for mosquito control, we analyzed the results of a 5-year OMWM/marsh restoration project to determine changes in mosquito larval production using GIS and geostatistical methods.</p> <p>Methods</p> <p>The following parameters were evaluated using "Before-After-Control-Impact" (BACI) design: frequency and geographic extent of larval production, intensity of larval production, changes in larval habitat, and number of larvicide applications. The analyses were performed using Moran's I, Getis-Ord, and Spatial Scan statistics on aggregated before and after data as well as data collected over time. This allowed comparison of control and treatment areas to identify changes attributable to the OMWM/marsh restoration modifications.</p> <p>Results</p> <p>The frequency of finding mosquito larvae in the treatment areas was reduced by 70% resulting in a loss of spatial larval clusters compared to those found in the control areas. This effect was observed directly following OMWM treatment and remained significant throughout the study period. The greatly reduced frequency of finding larvae in the treatment areas led to a significant decrease (~44%) in the number of times when the larviciding threshold was reached. This reduction, in turn, resulted in a significant decrease (~74%) in the number of larvicide applications in the treatment areas post-project. The remaining larval habitat in the treatment areas had a different geographic distribution and was largely confined to the restored marsh surface (i.e. filled-in mosquito ditches); however only ~21% of the restored marsh surface supported mosquito production.</p> <p>Conclusion</p> <p>The geostatistical analysis showed that OMWM demonstrated considerable potential for effective mosquito control and compatibility with other natural resource management goals such as restoration, wildlife habitat enhancement, and invasive species abatement. GPS and GIS tools are invaluable for large scale project design, data collection, and data analysis, with geostatistical methods serving as an alternative or a supplement to the conventional inference statistics in evaluating the project outcome.</p

    Anthropogenic impacts on mosquito populations in North America over the past century.

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    The recent emergence and spread of vector-borne viruses including Zika, chikungunya and dengue has raised concerns that climate change may cause mosquito vectors of these diseases to expand into more temperate regions. However, the long-term impact of other anthropogenic factors on mosquito abundance and distributions is less studied. Here, we show that anthropogenic chemical use (DDT; dichlorodiphenyltrichloroethane) and increasing urbanization were the strongest drivers of changes in mosquito populations over the last eight decades in areas on both coasts of North America. Mosquito populations have increased as much as tenfold, and mosquito communities have become two- to fourfold richer over the last five decades. These increases are correlated with the decay in residual environmental DDT concentrations and growing human populations, but not with temperature. These results illustrate the far-reaching impacts of multiple anthropogenic disturbances on animal communities and suggest that interactions between land use and chemical use may have unforeseen consequences on ecosystems

    Distribution and Abundance of Host-seeking Culex Species at Three Proximate Locations with Different Levels of West Nile Virus Activity

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    Culex species were monitored at three proximate sites with historically different West Nile virus (WNV) activities. The site with human WNV transmission (epidemic) had the lowest abundance of the putative bridge vectors, Culex pipiens and Cx. salinarius. The site with horse cases but not human cases (epizootic) had the highest percent composition of Cx. salinarius, whereas the site with WNV-positive birds only (enzootic) had the highest Cx. pipiens abundance and percent composition. A total of 29 WNV-positive Culex pools were collected at the enzootic site, 17 at the epidemic site, and 14 at the epizootic site. Published models of human risk using Cx. pipiens and Cx. salinarius as the primary bridge vectors did not explain WNV activity at our sites. Other variables, such as additional vector species, environmental components, and socioeconomic factors, need to be examined to explain the observed patterns of WNV epidemic activity

    A Human-Interactive Course of Action Planner for Aircraft Carrier Deck Operations

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    Aircraft carrier deck operations present a complex and uncertain environment in which time-critical scheduling and planning must be done, and to date all course of action planning is done solely by human operators who rely on experience and training to safely negotiate off -nominal situations. A computer decision support system could provide the operator with both a vital resource in emergency scenarios as well as suggestions to improve e fficiency during normal operations. Such a decision support system would generate a schedule of coordinated deck operations for all active aircraft (taxi, refuel, take o ff, queue in Marshal stack, land, etc.) that is optimized for effi ciency, amenable to the operator, and robust to the many types of uncertainty inherent in the aircraft carrier deck environment. This paper describes the design, implementation, and testing of a human-interactive aircraft carrier deck course of action planner. The planning problem is cast in the MDP framework such that a wide range of current literature can be used to fi nd an optimal policy. It is designed such that human operators can specify priority aircraft and suggest scheduling orders. Inverse reinforcement learning techniques are applied that allow the planner to learn from recorded expert demonstrations. Results are presented that compare various types of human and learned policies, and show qualitative and quantitative matching between expert demonstrations and learned policies.United States. Office of Naval Research (Science of Autonomy Program

    The Self-Designing High- Reliability Organization

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    Recent studies of large, formal organizations that perform complex, inherently hazardous, and highly technical task under conditions of tight coupling and severe time pressure have generally concluded that most will fail spectaculatory at some point, with attendant human and social const of great severity. The notion that accidents in these systems are normal, that is, to be expected given the coditions and risks of operations and risk of operation, appears to be as well grounded in experience as in theory

    Project ROI Report: Defining the Competitive and Financial Advantages of Corporate Responsibility and Sustainability

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    Corporate Responsibility (CR) practices have great potential to deliver financial returns on investment (ROI) as well as related business and competitive benefits. But it's not enough to engage in CR activities, one must manage them well. Companies should view their combined CR practices as value-creating assets. With proper design and sufficient investment, a company's "CR Assets" can support returns related to: * Share price and market value* Sales and revenue* Reputation and brand* Human resources* Risk and license to operateIt is time to move away from the debate over whether CR in the abstract creates or destroys value. Companies and their managers are able to exert some measure of both choice and control over the business-related benefits that their CR management will deliver. Like other investments, some CR initiatives will pan out and others won't. The implication for companies is to develop business-aligned and integrated CR strategies. This includes applying to CR some of the same management disciplines as any other business function

    The Self-Designing High-Reliability Organization: Aircraft Carrier Flight Operations at Sea

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    Of all activities studied by our research group, flight operations at sea is the closest to the edge of the envelope -operating under the most extreme conditions in the least stable environment, and with the greatest tension between preserving safety and reliability and attaining maximum operational efficiency

    Does e-learning policy drive change in Higher Education?: A case study relating models of organisational change to e-learning implementation

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    Due to the heightened competition introduced by the potential global market and the need for structural changes within organisations delivering e-content, e-learning policy is beginning to take on a more significant role within the context of educational policy per se. For this reason, it is becoming increasingly important to establish what effect such policies have and how they are achieved. This paper addresses this question, illustrating five ways in which change is understood (Fordist, evolutionary, ecological, community of practice and discourse-oriented) and then using this range of perspectives to explore how e-learning policy drives change (both organisational and pedagogic) within a selected higher education institution. The implications of this case are then discussed, and both methodological and pragmatic conclusions are drawn, considering the relative insights offered by the models and ways in which change around e-learning might be supported or promoted
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