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291.
Environmental and Ecological Statistics - 相似文献
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Effects of management and climate on elk brucellosis in the Greater Yellowstone Ecosystem. 总被引:1,自引:0,他引:1
Paul C Cross William H Edwards Brandon M Scurlock Eric J Maichak Jared D Rogerson 《Ecological applications》2007,17(4):957-964
Every winter, government agencies feed approximately 6000 metric tons (6 x 10(6) kg) of hay to elk in the southern Greater Yellowstone Ecosystem (GYE) to limit transmission of Brucella abortus, the causative agent of brucellosis, from elk to cattle. Supplemental feeding, however, is likely to increase the transmission of brucellosis in elk, and may be affected by climatic factors, such as snowpack. We assessed these possibilities using snowpack and feeding data from 1952 to 2006 and disease testing data from 1993 to 2006. Brucellosis seroprevalence was strongly correlated with the timing of the feeding season. Longer feeding seasons were associated with higher seroprevalence, but elk population size and density had only minor effects. In other words, the duration of host aggregation and whether it coincided with peak transmission periods was more important than just the host population size. Accurate modeling of disease transmission depends upon incorporating information on how host contact rates fluctuate over time relative to peak transmission periods. We also found that supplemental feeding seasons lasted longer during years with deeper snowpack. Therefore, milder winters and/or management strategies that reduce the length of the feeding season may reduce the seroprevalence of brucellosis in the elk populations of the southern GYE. 相似文献
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The reduction of SO2, HCl, and NO(x) concentrations using calcium magnesium acetate (CMA) as a novel sorbent in a simulated municipal waste incinerator flue gas was investigated. The reduction of individual SO2, HCl, and NO(x) concentrations was tested at 850 degrees C and it was found that CMA could reduce the SO2 concentration by 74%, HCl concentration by 64%, or NO(x) concentration by 94%. It was observed that individual SO2 or HCl capture increased with increasing initial oxygen concentration in the reacting gas or increasing sorbent input. NO(x) reduction decreased with increasing initial oxygen concentration in the reacting gas. The simultaneous reduction of SO2, HCl, and NO(x) concentrations by CMA was also investigated. It was found that CMA could simultaneously capture 60% SO2 and 61% HCl and reduce NO(x) concentrations by 26%, when the initial oxygen concentration in the reacting gas was 4%. During the simultaneous reduction of SO2, HCl, and NO(x), it was noted that as the initial oxygen concentration in the reacting gas increased, the efficiency of SO2 capture increased too, but the efficiency of HCl capture and the efficiency of NO(x) destruction decreased. 相似文献
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Paul Perkins 《The Environmentalist》1996,16(4):263-268
Summary Environmentally Sensitive Areas were introduced in Britain by the Ministry of Agriculture, Fisheries and Food during 1987. By 1994, the fourth round of designations had brought the total of such areas to 22. The environmental implications for the North Peak, which was designated as such an area in 1988, are discussed in the context of sheep farming and heather management, for these have shaped the patchwork of moorland ecosystems that give the North Peak its unique character.Paul Perkins is a research worker at the University of Huddersfield. He is currently undertaking research into how derelict mining land in West and South Yorkshire can be reclaimed for productive use. 相似文献
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