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151.
Pathogen-driven declines in animal populations are increasingly regarded as a major conservation issue. The Tasmanian devil (Sarcophilus harrisii) is threatened with extinction by devil facial tumor disease, a unique transmissible cancer. The disease is transmitted through direct transfer of tumor cells, which is possible because the genetic diversity of Tasmanian devils is low, particularly in the major histocompatibility complex genes of the immune system. The far northwest of Tasmania now holds the last remaining disease-free wild devil populations. The recent discovery of unique major histocompatibility complex genotypes in the northwestern region of Tasmania has raised the possibility that some animals may be resilient to the disease. We examined the differences in the epidemiology and population effects of devil facial tumor disease at 3 well-studied affected sites in eastern Tasmania and 1 in western Tasmania (West Pencil Pine). In contrast to the 3 eastern sites, there has been no rapid increase in disease prevalence or evidence of population decline at West Pencil Pine. Moreover, this is the only onsite at which the population age structure has remained unaltered 4 years after the first detection of disease. The most plausible explanations for the substantial differences in population effects and epidemiology of the disease between eastern and western sites are geographic differences in genotypes or phenotypes of devils and functional differences between tumor strains in the 2 regions. We suggest that conservation efforts focus on identifying whether either or both these explanations are correct and then, if resistance alleles exist, to attempt to spread the resistant alleles into affected populations. Such assisted selection has rarely been attempted for the management of wildlife diseases, but it may be widely applicable.  相似文献   
152.
我国水生生物水质基准推导的物种选择   总被引:3,自引:2,他引:1  
水生生物水质基准旨在保护水生生物不受水体中化学物质的有害影响,是水质基准体系的重要组成部分.不同区域水生态系统的生物区系不同,导致基准值也会存在差异.在综合研究美国、欧盟、加拿大、荷兰、澳大利亚和新西兰等国家和地区在推导水生生物水质基准的物种选择及其考虑因素的基础上,初步研究我国水生生物水质基准推导的物种选择原则.结果表明:推导我国水生生物水质基准需要选择来自8科的水生生物,分别为鲤科鱼类、硬骨鱼纲中的另一科、两栖动物纲的一科、浮游动物中节肢动物门和轮虫动物门各一科、底栖动物中节肢动物门和环节动物门各一科及一种最敏感的大型水生植物(或浮游植物),可全面代表我国水生态系统不同的营养级和生命形式.   相似文献   
153.
王梓璇  王圃  王颖  彭翰  华佩  张晋 《环境科学学报》2021,41(7):2942-2950
随着工业的快速发展,水体中污染物超标事件时有发生,造成了较严重的水环境污染问题.水环境监测与预报是环境科学研究的重要内容.为了实现地表水砷(As)污染的准确预报,本研究提出小波分解、遗传算法与BP人工神经网络的耦合建模方法,并结合某河流监测站1998—2016年共19年的地表水质监测数据,通过皮尔逊相关系数和信息指标评价法对模型输入变量进行筛选,最后对比分析了在不同水质参数输入情况下BP人工神经网络(BPNN)、遗传算法改进的BPNN(GABP)、小波-遗传BPNN耦合模型(W-GABP)对后6年(2011—2016年) As浓度预测结果的均方根误差(RMSE)、决定系数(R2)、平均绝对百分比误差(MAPE),以确立最优模型.结果表明:①多水质参数BPNN、GABP与W-GABP耦合模型预测结果的MAPE分别为17.51%、15.98%、14.46%,单水质参数BPNN、GABP与W-GABP耦合模型预测结果的MAPE分别为18.78%、16.74%、7.83%;②小波分解数据前处理及遗传算法均能较大程度地提高预测模型的精度;③对于地表水水质预报,需对比不同模型在不同输入变量下的预测结果,以获得最佳的预测精度.单水质参数输入的W-GABP耦合模型能较准确地预报地表水As浓度的变化情况,对数据缺乏地区水质监控和地表水As污染防治具有重要意义.  相似文献   
154.
为了研究应急物资的实物储备与协议企业生产能力储备相结合的储备模式协调性,降低企业自身应对突发生产安全事故的物资储备成本,建立多情景生产安全事故下的企业应急物资实物储备场所和协议储备企业选址的协调优化模型,利用Lingo软件进行求解,并以石油储罐火灾的应急物资储备为背景设计算例,验证相关模型及方法的有效性。结果表明:提出的企业应急物资储备体系,能够在降低应急物资储备成本的同时,保持日常应急救灾能力。  相似文献   
155.
天津市东疆港区绿化树种适应性评价   总被引:2,自引:0,他引:2  
筛选适生树种是盐碱地绿化工作的技术关键。天津市东疆港区的土壤是淤泥质盐渍土,在该区域绿化树种现场调查的基础上,依据树种的适生能力、生态效益和实际生长效果建立了综合评价多级指标体系。通过确定各指标因子的权重和评判标准,计算出各树种的综合指数,并依次划分为骨干树种、重要树种、辅助和补充树种以及不适宜树种4个级别,该综合评价多级指标体系为类似盐碱地绿化建设工程提供了实践和理论依据。  相似文献   
156.
The present paper provides a conceptual and empirical examination regarding the relevance of the construct curiosity for work‐related outcomes. On the basis of a review and integration of the literature regarding the construct itself, the construct is conceptually linked with performance in the work context. In line with a confirmatory research strategy, the sample of the present study (N = 320) has requirements which reflect this conceptual link. Results from a concurrent validation study confirmed the hypothesis regarding the significance of curiosity for job performance (r = .34). Furthermore, incremental validity of curiosity above 12 cognitive and non‐cognitive predictors for job performance suggests that curiosity captures variance in the criterion that is not explained by predictors traditionally used in organizational psychology. It is concluded that curiosity is an important variable for the prediction and explanation of work‐related behavior. Furthermore, given the dramatic changes in the world of work, the importance is likely to rise, rather than to decline, which has important implications for organizational theories and applied purposes, such as personnel selection. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
157.
Safety reports are mandatory documents in member states of European Union whenever any threshold limits of amounts of either stored or processed hazardous substances are exceeded. After a short introduction to EU Seveso Directives on major-accident hazards involving dangerous substances and to the transposition and implementation by member states, with a brief comment on last 2012/18/EU Directive (also known as Seveso III directive), the paper focuses on drafting of safety reports for industrial activities involving solid explosives. Specifically, the quantitative assessment of consequences from detonation is tackled respect to the side-on overpressure and the debris production. Both direct and inverse problems are illustrated to determine respectively the overpressure value at a given distance, and the explosive amount that allows respecting the regulations. Their solution is based on either analytic or numerical techniques and being based on recent scientific publications on the matter either evaluates or zeroes nonlinear algebraic equations. The availability of these equations avoids grounding the consequences assessment on diagrams and nomograms that otherwise would lead to interpretation and usage errors besides avoiding the automatic solution of the inverse problem. The paper focuses also on details such as embankment, crater, munitions, rocket propellant, building structure, and wall material that, at different levels, play a role in the assessment of detonation consequences. A discussion on debris formation, the available literature, and the evaluation of the impact probability of fragments on both fixed and moving targets closes the paper.  相似文献   
158.
周鹏飞 《四川环境》2013,32(2):37-41
曝气器是污水处理厂的核心设备。目前广泛运用的鼓风机微孔曝气是一种高效节能的曝气方式。选择适当的微孔曝气器是非常重要的,不仅保障污水处理效果稳定,运行成本较低,还能节省设备投资和维护费用。结合微孔曝气器在污水处理厂的运用效果,分析了各种微孔曝气器的性能、特点和优劣,并对污水处理厂微孔曝气器的选型进行了探讨。  相似文献   
159.
Like many conservation organizations and federal and state agencies, The Nature Conservancy is in the process of large-scale planning and prioritization efforts. To improve the efficiency of these planning efforts, the Conservancy has developed a methodology for these efforts. The results of these planning efforts will be a conservation blueprint which identifies the conservation areas necessary for conserving biodiversity and a subset of those areas where the Conservancy will focus its immediate efforts over the next 10 years. The subset of all the conservation areas identified in the planning process help The Nature Conservancy determine where it will work. This subset of areas (referred to as action sites) is selected using a tool which ranks key criteria for each conservation area. These criteria include the current conservation status of each area, complementarity to other areas selected, the diversity and viability of targets at the area, the urgency and degree of threats to the targets, the feasibility or opportunity to abate the threats at the area and the leverage potential of working at a conservation area. Taken together, these criteria help planners to select the areas where they will focus their conservation efforts.  相似文献   
160.
Sexual ornaments might reliably indicate the ability to cope with parasites and diseases, and a better ability to mount a primary inflammatory response to a novel challenge. Carotenoid-based ornaments are amongst the commonest sexual signals of birds and often influence mate choice. Because carotenoids are immuno-stimulants, signallers may trade-off allocating these to ornamental colouration or using them for immune responses, so carotenoid-based ornaments might be particularly useful as honest indicators of immuno-compentence. Tetraonid birds, such as the red grouse Lagopus lagopus scoticus, exhibit supra-orbital yellow-red combs, a conspicuous ornament which functions in intra- and inter-sexual selection. The colour of combs is due to epidermal pigmentation by carotenoids, while their size is testosterone-dependent. In this study, I investigated whether comb characteristics, and in particular, comb colour, indicated immuno-competence in free-living male red grouse. I assessed T-cell-mediated immunity using a standardised challenge with phytohaemagglutinin. Red grouse combs reflect in the red and in the ultraviolet spectrum of light, which is not visible to humans but that grouse most likely see, so I measured comb colour across the whole bird visible spectrum (300-700 nm) using a reflectance spectrometer. I found that males with bigger and redder combs, but with less ultraviolet reflectance, had greater T-cell-mediated immune response. Comb colour predicted T-cell-mediated immune response better than comb size, indicating that the carotenoid-based colouration of this ornament might reliably signal this aspect of male quality.  相似文献   
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