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排序方式: 共有253条查询结果,搜索用时 31 毫秒
141.
A method for setting air quality standards for long-term cumulative exposures of a population based on epidemiological studies has been developed. It uses exposure estimates interpolated from monitoring stations to zip code centroids, each month applied to zip code by month residence histories of the population. Two alternative cumulative exposure indices are used—hours in excess of a threshold, and the sum of concentrations above a threshold. The indices are then used with multiple logistic regression models for the health outcome data to form dose response curves for relative risk, adjusting for covariates. These curves are useful for determination of at what exposure amounts and threshold levels, effects which have both statistical and public health significance begin to occur. The method is applied to a ten year follow-up of a sub cohort of 7,343 members of the National Cancer Institute-funded Adventist Health Study. Up to 20 years of residence history was available. Analysis for prevalence of symptoms was conducted for four air pollutants— total oxidants, sulfur dioxide, nitrogen dioxide, and total suspended particulates. For each pollutant, cumulated exposures were calculated above each of five different thresholds. Statistically significant effects were noted for total suspended particulates, total oxidants, sulfur dioxide, past and passive smoking.  相似文献   
142.
Conflicts between the conservation of biodiversity and other human activities have been and continue to be of increasing concern in the European Union, often having important political, economic, and environmental repercussions. These conflicts have been addressed in the European Union by using a wide array of top down and bottom up tools, with varying degrees of success. A new challenge is now facing Europe with the integration of 10 new countries in the European Union (EU) and an additional range of biodiversity-rich habitats placed under EU legislation. The rich biodiversity of the central and eastern European countries (CEEC) is likely to be threatened by some aspects of the integration process, and conflicts between the conservation of biodiversity and other human activities are expected. In this paper, we review certain existing conflicts between biodiversity conservation and human activities in the CEEC, expected conflicts associated with integration to the EU, particularly in terms of new policy and legislation implementation, and, finally, explore possible conflict management options.  相似文献   
143.
This study sought to extend validation of a cyclodextrin based extraction method for the assessment of PAH-biodegradation potential to complex multi-contaminant matrices. To this end, four reference materials (RMs) were produced by blending, in different proportions, soils impacted with diesel, lubricating oil and spent oxide. These reference materials had modest ∑PAH (16 US EPA) concentrations that ranged from 5.6 ± 0.5 to 44.4 ± 4.5 mg kg−1. However, extractable petroleum hydrocarbon (EPH) concentrations were comparatively high (up to 2520 ± 204 mg kg−1). To complement these RMs, two further soils from a municipal gas plant (MGP) with highly elevated concentration of PAHs ranging from 877 ± 52 to 2620 ± 344 mg kg−1 were also tested. Results showed, regardless of matrix complexity, that PAH biodegradation within the four RM substrates, and two MGP soils correlated well with biodegradation predicted by hydroxypropyl-β-cyclodextrin (HPCD) extraction.  相似文献   
144.
Cultural heritage sites form an unrenewable asset that is threatened by natural disasters. Given the high bushfire risk, mandatory Bush Fire Risk Management Plans have been drawn up throughout New South Wales, Australia. We compared their mandatory provisions for the protection of heritage assets with an 'Ideal Heritage Disaster Plan', containing a series of non-negotiable elements. The examined plans fell well short of the ideal. Preparedness Plans generally lacked a discussion of suppression techniques (for historic heritage), prevention, prescribed drills and communication procedures. None of the Response Plans or Recovery Plans contained any of the required core elements, such as rapid suppression techniques and stabilisation procedures. Where aspects were covered, they were addressed in an inadequate level of detail. The overall quality of the cultural heritage components of the plans is judged to be poor. Suggestions are made on how to improve the situation if heritage assets are to have a future following bushfire events.  相似文献   
145.
BACKGROUND: Call centres (CCs) are among the most rapidly growing forms of workplaces in Sweden. The purpose of the study was to describe and compare working conditions between operators at internal and external CC companies and work tasks of different complexity. METHOD: A questionnaire was answered by 1183 operators, 848 women and 335 men, from 28 different CCs. The questionnaire covered background factors, employment, working hours and remuneration, call logging and monitoring, duties, computer work and workplace design during the previous month. RESULTS: Operators at external companies and operators with low-complexity work tasks were younger, more often employed by the hour and worked on a varying roster. They spent longer time on customer calls and had less varied tasks. Additional remuneration, call logging and monitoring were more common at external companies and among operators with low-complexity work tasks. CONCLUSION: The working conditions varied between internal and external CCs. There was also a variation in working conditions between work tasks of different complexity. There were aspects of supervision style and organization of work at CCs, especially at external ones and those with low-complexity tasks that could introduce stress and lack of well being among the staff.  相似文献   
146.
147.
Dosskey, Michael G., Philippe Vidon, Noel P. Gurwick, Craig J. Allan, Tim P. Duval, and Richard Lowrance, 2010. The Role of Riparian Vegetation in Protecting and Improving Chemical Water Quality in Streams. Journal of the American Water Resources Association (JAWRA) 46(2):261-277. DOI: 10.1111/j.1752-1688.2010.00419.x Abstract: We review the research literature and summarize the major processes by which riparian vegetation influences chemical water quality in streams, as well as how these processes vary among vegetation types, and discuss how these processes respond to removal and restoration of riparian vegetation and thereby determine the timing and level of response in stream water quality. Our emphasis is on the role that riparian vegetation plays in protecting streams from nonpoint source pollutants and in improving the quality of degraded stream water. Riparian vegetation influences stream water chemistry through diverse processes including direct chemical uptake and indirect influences such as by supply of organic matter to soils and channels, modification of water movement, and stabilization of soil. Some processes are more strongly expressed under certain site conditions, such as denitrification where groundwater is shallow, and by certain kinds of vegetation, such as channel stabilization by large wood and nutrient uptake by faster-growing species. Whether stream chemistry can be managed effectively through deliberate selection and management of vegetation type, however, remains uncertain because few studies have been conducted on broad suites of processes that may include compensating or reinforcing interactions. Scant research has focused directly on the response of stream water chemistry to the loss of riparian vegetation or its restoration. Our analysis suggests that the level and time frame of a response to restoration depends strongly on the degree and time frame of vegetation loss. Legacy effects of past vegetation can continue to influence water quality for many years or decades and control the potential level and timing of water quality improvement after vegetation is restored. Through the collective action of many processes, vegetation exerts substantial influence over the well-documented effect that riparian zones have on stream water quality. However, the degree to which stream water quality can be managed through the management of riparian vegetation remains to be clarified. An understanding of the underlying processes is important for effectively using vegetation condition as an indicator of water quality protection and for accurately gauging prospects for water quality improvement through restoration of permanent vegetation.  相似文献   
148.
Recent increases in ivory poaching have depressed African elephant populations. Successful enforcement has led to ivory stockpiling. Stockpile destruction is becoming increasingly popular, and most destruction has occurred in the last 5 years. Ivory destruction is intended to send a strong message against ivory consumption, both in promoting a taboo on ivory use and catalyzing policy change. However, there has been no effort to establish the distribution and extent of media reporting on ivory destruction events globally. We analyzed media coverage of the largest ivory destruction event in history (Kenya, 30 April 2016) across 11 nation states connected to ivory trade. We used an online‐media crawling tool to search online media outlets and subjected 5 of the largest print newspapers (by circulation) in 5 nations of interest to content analysis. Most online news on the ivory burn came from the United States (81% of 1944 articles), whereas most of the print news articles came from Kenya (61% of 157 articles). Eighty‐six to 97% of all online articles reported the burn as a positive conservation action, whereas 4–50% discussed ivory burning as having a negative impact on elephant conservation. Most articles discussed law enforcement and trade bans as effective for elephant conservation. There was more relative search interest globally in the 2016 Kenyan ivory burn than any other burn in 5 years. Ours is the first attempt to track the reach of media coverage relative to an ivory burn and provides a case study in tracking the effects of a conservation‐marketing event.  相似文献   
149.
McCauley DJ  Keesing F  Young TP  Allan BF  Pringle RM 《Ecology》2006,87(10):2657-2663
Many large mammal species are declining in African savannas, yet we understand relatively little about how these declines influence other species. Previous studies have shown that the removal of large herbivorous mammals from large-scale, replicated experimental plots results in a dramatic increase in the density of small mammals, an increase that has been attributed to the relaxation of competition between rodents and large herbivores for food resources. To assess whether the removal of large herbivores also influenced a predator of small mammals, we measured the abundance of the locally common olive hissing snake, Psammophis mossambicus, over a 19-mo period in plots with and without large herbivores. Psammophis mossambicus was significantly more abundant in plots where large herbivores were removed and rodent numbers were high. Based on results from raptor surveys and measurements of vegetative cover, differences in snake density do not appear to be driven by differences in rates of predation on snakes. Instead, snakes appear to be responding numerically to greater abundances of small-mammal prey in areas from which large herbivores have been excluded. This is the first empirical demonstration of the indirect effects of large herbivores on snake abundance and presents an interesting example of how the influence of dominant and keystone species can move through a food web.  相似文献   
150.
This is the latest in a series of reviews of research on graduated driver licensing (GDL) published in the Journal of Safety Research, covering the period January 1, 2010-June 1, 2012 and works in progress. The intent is to keep researchers and policy makers current regarding the existing state of knowledge about GDL, and to identify information gaps and areas where clarification of research findings are needed. The recent research indicates that we continue to learn about ways to extend GDL benefits, but there remain important questions in need of further inquiry. In terms of impact on industry, the review provides guidance for the future GDL research agenda.  相似文献   
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