2,557 research outputs found

    Economic Analysis of an Integrated Wind-Hydrogen Energy System for a Small Alaska Community

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    Wind-hydrogen systems provide one way to store intermittent wind energy as hydrogen. We explored the hypothesis that an integrated wind-hydrogen system supplying electricity, heat, and transportation fuel could serve the needs of an isolated (off-grid) Alaska community at a lower cost than a collection of separate systems. Analysis indicates that: 1) Combustible Hydrogen could be produced with current technologies for direct use as a transportation fuel for about $15/gallon-equivalent; 2) The capital cost of the wind energy rather than the capital cost of electrolyzers dominates this high cost; and 3) There do not appear to be diseconomies of small scale for current electrolyzers serving a a village of 400 people.United States Department of Energy. DOE Award Number: DE-FC26-01NT41248Introduction / Executive Summary / Experimental Methods / Results and Discussion / Conclusion / Bibliography / Appendix: Associated Excel Workbook

    A model for large-scale volcanic plumes on Io: Implications for eruption rates and interactions between magmas and near-surface volatiles.

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    Volcanic plumes deposit magmatic pyroclasts and SO2 frost on the surface of Io. We model the plume activity detected by Galileo at the Pillan and Pele sites from 1996 to 1997 assuming that magmatic eruptions incorporate liquid SO2 from near-surface aquifers intersecting the conduit system and that the SO2 eventually forms a solid condensate on the ground. The temperature and pressure at which deposition of solid SO2 commences in the Ionian environment and the radial distance from the volcanic vent at which this process appears to occur on the surface are used together with observed vertical heights of plumes to constrain eruption conditions. The temperature, pressure, and density of the gas–magma mixtures are related to distance from the vent using continuity and conservation of energy. Similar eruption mass fluxes of order 5x10^7 kg s^1 are found for both the Pillan and the Pele plumes. The Pele plume requires a larger amount of incorporated SO2 (29–34 mass %) than the Pillan plume (up to 6 mass%). Implied vent diameters range from c. 90m at Pillan to c. 500 m at Pele. The radial extents of the optically dense, isothermal, incandescent parts of the eruption plumes immediately above the vents are 100 m at Pillan and 1300 m at Pele. Gas pressures in the vents are 20 kPa at Pillan and 2 kPa at Pele and the eruption conditions appear to be supersonic in both cases, though only just so at Pele

    The Impact of Drought on Coastal Ecosystems in the Carolinas

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    2012 S.C. Water Resources Conference - Exploring Opportunities for Collaborative Water Research, Policy and Managemen

    Village Wind Diesel Hydrogen Report

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    The cost of energy in hub and satellite villages has long been a major contributor to the cost of living in rural Alaska. Wind energy currently displaces a portion of the diesel fuel used for power generation in 5 Alaskan villages; Kotzebue, Selawick, Tooksook Bay, Wales and Saint Paul Island. Numerous other villages are being considered as potential sites for integration of wind generation into the diesel electric system. Wind diesel electric systems are showing promise as sources of long term flat priced electricity for village power needs. Since the price of wind doesn’t change the cost of the wind generated component of electricity is not subject to fuel price volatility. As with any renewable energy the upfront capital cost is higher than diesel engines. Wind diesel alone however, does not address the broader energy needs of rural communities. Fuels such as gasoline, diesel and heating oil have to be transported to the village. This report explores the potential of using wind to produce hydrogen for transportation and heating fuels at a small, 400 person and large, 4000 person village.NETL, Arctic Energy Office (U.S. Department of Energy); Alaska Conservation Foundatio

    Detecting changes, causes and future prospects of Kenyan wetlands and their conservation

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    Wetlands around the globe have been altered, degraded or lost through a wide range of human activities. A variety of conservation action is presently undertaken in response to these changes, and much of this work aims to: promote the wise and sustainable use of wetland resources, maintain ecological character at wetland sites, and also to prevent degradation and loss of wetlands at local, national and international scales. Kenyan wetlands play a number of roles in the socio-economic development of the country despite being under intense pressure. The driving forces continue to increase in intensity with time and there is a need for immediate action in order to restore their ecological character and integrity. The findings of this review provides an introduction, changes, causes, challenges and way forward as the conservation of Kenyan wetlands is concerned

    Non-steroidal anti-inflammatory drugs (NSAIDs): Physiotherapists' use, knowledge and attitudes

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    This paper reports on a survey regarding physiotherapists’ knowledge, use and attitudes to non–steroidal anti–inflammatory drugs (NSAIDs), some of which have recently been re–scheduled to non–prescription dispensing. A written survey instrument was developed and administered to 750 physiotherapists in South Australia, Tasmania and the Australian Capital Territory (50% of the registered physiotherapists). Responses were received from 285 physiotherapists. The survey identified opportunities for patient misuse and misadventures with NSAIDs in conjunction with physiotherapy management. Differences in physiotherapists’ understanding of the dosage and actions of oral and topic administrations of NSAIDs were highlighted, as were the moral and ethical responsibilities of physiotherapists to patients considering taking NSAIDs. The study identified the need for regular professional updates on quality use of NSAIDs

    Analysis of EEC Regulation 2092/91 in relation to other national and international organic standards

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    This Deliverable 3.2 report presents an analysis of differences between EEC Regulation 2092/91 and other organic standards and their implementation, using a specially developed database (www.organicrules.org). It further reports on database development. The work was carried out as part of the “EEC 2092/91 (Organic) Revision” STREP project (No. SSPE-CT- 2004-502397) within the EU 6th Framework Programme. The main objective was to identify differences in organic standards in relation to Regulation (EEC) 2092/91 and to analyse selected national governmental and private organic standards with the aim of identifying specific areas in the (EEC) 2092/91 where revision in terms of harmonisation, regionalisation or simplification may be possible

    Cost-effectiveness and Benefit-to-Harm Ratio of Risk-Stratified Screening for Breast Cancer: A Life-Table Model.

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    IMPORTANCE: The age-based or "one-size-fits-all" breast screening approach does not take into account the individual variation in risk. Mammography screening reduces death from breast cancer at the cost of overdiagnosis. Identifying risk-stratified screening strategies with a more favorable ratio of overdiagnoses to breast cancer deaths prevented would improve the quality of life of women and save resources. OBJECTIVE: To assess the benefit-to-harm ratio and the cost-effectiveness of risk-stratified breast screening programs compared with a standard age-based screening program and no screening. DESIGN, SETTING, AND POPULATION: A life-table model was created of a hypothetical cohort of 364 500 women in the United Kingdom, aged 50 years, with follow-up to age 85 years, using (1) findings of the Independent UK Panel on Breast Cancer Screening and (2) risk distribution based on polygenic risk profile. The analysis was undertaken from the National Health Service perspective. INTERVENTIONS: The modeled interventions were (1) no screening, (2) age-based screening (mammography screening every 3 years from age 50 to 69 years), and (3) risk-stratified screening (a proportion of women aged 50 years with a risk score greater than a threshold risk were offered screening every 3 years until age 69 years) considering each percentile of the risk distribution. All analyses took place between July 2016 and September 2017. MAIN OUTCOMES AND MEASURES: Overdiagnoses, breast cancer deaths averted, quality-adjusted life-years (QALYs) gained, costs in British pounds, and net monetary benefit (NMB). Probabilistic sensitivity analyses were used to assess uncertainty around parameter estimates. Future costs and benefits were discounted at 3.5% per year. RESULTS: The risk-stratified analysis of this life-table model included a hypothetical cohort of 364 500 women followed up from age 50 to 85 years. As the risk threshold was lowered, the incremental cost of the program increased linearly, compared with no screening, with no additional QALYs gained below 35th percentile risk threshold. Of the 3 screening scenarios, the risk-stratified scenario with risk threshold at the 70th percentile had the highest NMB, at a willingness to pay of £20 000 (US 26800)perQALYgained,witha7226 800) per QALY gained, with a 72% probability of being cost-effective. Compared with age-based screening, risk-stratified screening at the 32nd percentile vs 70th percentile risk threshold would cost £20 066 (US 26 888) vs £537 985 (US $720 900) less, would have 26.7% vs 71.4% fewer overdiagnoses, and would avert 2.9% vs 9.6% fewer breast cancer deaths, respectively. CONCLUSIONS AND RELEVANCE: Not offering breast cancer screening to women at lower risk could improve the cost-effectiveness of the screening program, reduce overdiagnosis, and maintain the benefits of screening

    Mapping the e-Learning Assessment Domain: Concept Maps for Orientation and Navigation

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    Concept or Topic Maps have long been used as a method of categorizing and organizing information about a domain. Building them can help people conceptualize an area and spot trends or gaps, and as a presentation method they quickly provide an overview and general impression of a space. We are currently constructing a Reference Model of the Assessment Domain that takes the form of a highly interlinked dynamic website. This represents the assessment domain via the software, projects, standards and use cases of which it is composed. In this paper we present our efforts to create complimentary concept maps of the assessment domain, not as an overview, but for navigation and orientation within the domain. These concept maps, which model resources and activities independently, have been corroborated with practitioners in the e-learning community