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ABSTRACT: The traditional strong role of interest groups in water resources policy making has been modified recently by the introduction of many environmental groups. The new groups differ from traditional groups in their relatively modest resources and their relative lack of access to traditional decision points. This paper examines the extent to which the new groups differ in their perceptions of the effectiveness of tactics and in their use of tactics, taking into account group resources and group access to decision makers.  相似文献   
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This study examines the establishment patterns of exotic and ruderal species along trail corridors in grassland areas of the Colorado Front Range. The effects of trail presence, trail age, and trail traffic levels on exotic and ruderal species establishment are explored to ascertain the potential impacts of trails on surrounding vegetation. Established trails exhibited a greater presence of exotic and ruderal species along the immediate trailside, showing that disturbed trailsides tend to encourage the growth of these species over time. Furthermore, the established trails exhibited significantly less native, nonruderal, and overall species richness at the trailside. These trailside patterns did not show a significant spread away from the trail edge, even after prolonged time periods. Finally, higher trail use tended to hasten the establishment of exotic species along the trailside. The trails did not introduce new species to the recreation areas; rather they acted as reorganizational tools for species that were already present in the study sites.  相似文献   
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Whales repetitively dive deep to feed and should be susceptible to decompression syndrome, though they are not known to suffer the associated pathologies. Avascular osteonecrosis has been recognized as an indicator of diving habits of extinct marine amniotes. Vertebrae of 331 individual modern and 996 fossil whales were subjected to macroscopic and radiographic examination. Avascular osteonecrosis was found in the Oligocene basal odontocetes (Xenorophoidea) and in geologically younger mysticetes, such as Aglaocetus [a sister taxon to Balaenopteridae + (Balaenidae + Eschrichtiidae) clade]. These are considered as early "experiments" in repetitive deep diving, indicating that they independently converged on their similar specialized diving physiologies.  相似文献   
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This paper uses a large database of multiple birth cohorts to study relationships between air pollution exposure and non-infant children's respiratory health outcomes. We observe several years of early-life health treatments for hundreds of thousands of English children. Three distinct research designs account for potential socioeconomic, behavioral, seasonal, and economic confounders. We find that marginal increases in carbon monoxide and ground-level ozone are associated with statistically significant increases in children's contemporaneous respiratory treatments. We also find that carbon monoxide exposure over the previous year has an effect on children's health that goes above and beyond contemporaneous exposure alone.  相似文献   
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Several extinct sperm whales (stem Physeteroidea) were recently proposed to differ markedly in their feeding ecology from the suction-feeding modern sperm whales Kogia and Physeter. Based on cranial, mandibular, and dental morphology, these Miocene forms were tentatively identified as macroraptorial feeders, able to consume proportionally large prey using their massive teeth and robust jaws. However, until now, no corroborating evidence for the use of teeth during predation was available. We report on a new specimen of the stem physeteroid Acrophyseter, from the late middle to early late Miocene of Peru, displaying unusual bony outgrowths along some of the upper alveoli. Considering their position and outer shape, these are identified as buccal maxillary exostoses. More developed along posterior teeth and in tight contact with the high portion of the dental root outside the bony alveoli, the exostoses are hypothesized to have developed during powerful bites; they may have worked as buttresses, strengthening the teeth when facing intense occlusal forces. These buccal exostoses further support a raptorial feeding technique for Acrophyseter and, indirectly, for other extinct sperm whales with a similar oral apparatus (Brygmophyseter, Livyatan, Zygophyseter). With a wide size range, these Miocene stem physeteroids were major marine macropredators, occupying ecological niches nowadays mostly taken by killer whales.  相似文献   
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‘Live as domestic a life as possible. Have your child with you all the time. Lie down an hour after each meal. Have but two hours intellectual life a day. And never touch pen, brush or pencil as long as you live’. Dr S. Weir Mitchell, 1855 When Dr Mitchell, purportedly the greatest North American nerve specialist of his time, gave the above advice to his patient Charlotte Perkins Gilman, he almost certainly believed he was helping her get over a severe nervous condition. Fortunately, she did not take his advice. Instead she devoted herself to the study of economics and regained her health. The perspectives offered to working women by many a modern day Dr Mitchell appear to have changed somewhat in subtlety, but little in kind. For example, the August 18, 1986 cover of Fortune magazine featured a beaming mother and cherubic child illustrating the lead article, entitled ‘Why women are bailing out’. The article goes on to tell why four of the ‘best’ women MBAs had quit the workforce. One stated ‘I had to hire and fire people … I just don't want the hassle’ (of corporate life). Another having passed up a promotion at a Houston bank, ‘quit to have her first child’ and after her second had no plans to go back to work. A third complained: ‘I just couldn't do it. I watched other women sliding as they tried to juggle both career and family, making themselves crazy in the process’. And the fourth left a big accounting firm because the ‘hours were bad, and is now happier as a “part time teacher”’. While the Fortune article mentioned several reasons for women's leaving the corporate world ranging from competing family demands to discrimination, the underlying messages were clearly that mothers have to choose between children and career and that the business world is too cold, uncaring and tough for women, in a word no place for a lady. A chorus of such articles have appeared in the popular media warning against the dangers of career commitment for women, which are said to include everything from burnout, infertility, alcoholism, heart attacks to terminal spinsterhood (Faludi, 1991). More serious treatments emanating from academia have often reached similar conclusions. These dire pronouncements are especially influential to young women contemplating a professional or managerial career, but indeed those already in such careers may also wonder if they have made a bad choice. To answer such questions, this paper will explore some aspects of the relationship between career and emotional health and well-being for a group of highly successful career women.  相似文献   
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