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81.
Most studies of social polygyny in birds have examined male provisioning on the basis of the number of feeding visits. This may be misleading if males compensate for infrequent visits by bringing larger prey at each visit. We investigated nestling provisioning in the socially polygynous great reed warbler, Acrocephalus arundinaceus, in south Central Sweden in 1996–1997. We collected data on rate of feeding visits, prey size and the amount of biomass delivered by males and females. Males had lower rates of feeding visits and provided smaller prey to nestlings in secondary than in monogamous and primary nests. Secondary females had higher rates of feeding visits and brought larger prey than monogamous and primary females. These results confirm that secondary females face a potential cost of polygyny through a lower rate of male feeding, and that this cost was reinforced by the significantly lower male provisioning rate (biomass h–1) at secondary nests. Secondary females compensated for the lack of male assistance by increasing their rate of feeding and bringing larger prey. As a result, offspring in nests of secondary females received as much food as did those in nests of primary females. Prey load size increased with the parent’s proportion of feeding visits, suggesting that parents use different feeding strategies depending on their amount of responsibility for nestling provisioning. We suggest that parents which take the main responsibility for nestling feeding have to forage further away from the nest, and based on optimal-foraging theory, they should then on average bring larger prey to their nest. Received: 4 April 1999 / Received in revised form: 12 October 1999 / Accepted: 23 October 1999  相似文献   
82.
Previous assessments of the effectiveness of protected areas (PAs) focused primarily on changes in human pressure over time and did not consider the different human-pressure baselines of PAs, thereby potentially over- or underestimating PA effectiveness. We developed a framework that considers both human-pressure baseline and change in human pressure over time and assessed the effectiveness of 338 PAs in China from 2010 to 2020. The initial state of human pressure on PAs was taken as the baseline, and changes in human pressure index (HPI) were further analyzed under different baselines. We used the random forest models to identify the management measures that most improved effectiveness in resisting human pressure for the PAs with different baselines. Finally, the relationships between the changes in the HPI and the changes in natural ecosystems in PAs were analyzed with different baselines. Of PAs with low HPI baselines, medium HPI baselines, and high HPI baselines, 76.92% (n=150), 11.11% (n=12), and 22.86% (n=8) , respectively, showed positive effects in resisting human pressure. Overall, ignoring human-pressure baselines somewhat underestimated the positive effects of PAs, especially for those with low initial human pressure. For PAs with different initial human pressures, different management measures should be taken to improve effectiveness and reduce threats to natural ecosystems. We believe our framework is useful for assessing the effectiveness of PAs globally, and we recommend it be included in the Convention on Biological Diversity Post-2020 Strategy.  相似文献   
83.
利用火灾模拟软件FDS,以四川消防研究所高层实验塔二层为原型建立模型,对防烟空气幕的防烟有效性进行研究。本次实验在前室内设置测点,测定前室内的温度及CO浓度。实验结果表明:在未设置防烟空气幕时,前室内1.25m高度以上的测点温度稳定后均在35~45℃之间,CO浓度最大达到180ppm;在设置风幕后,前室内1.25m高度以上的测点温度稳定后在20~30℃之间,CO浓度最大为75.7ppm。因此,防烟空气幕能有效的减少烟气的进入量,降低进入前室的烟气的温度及有害气体浓度,为人员的安全疏散赢得时间。  相似文献   
84.
A tool (called CESMA) was developed to carry out cost–benefit analyses and cost-effectiveness analyses of prevention investments for avoiding major accidents. A wide variety of parameters necessary to calculate both the costs of the considered preventive measures and the benefits related with the avoidance of accidents were identified in the research. The benefits are determined by estimating the difference in (hypothetical) major accident costs without and with the implementation of a preventive measure. As many relevant costs and benefits as possible were included into the tool, based on literature and expert opinion, in order to be able to deliver an all-embracing cost–benefit analysis and cost-effectiveness analysis to assist in the investment decision process. Because major accidents are related to extremely low frequencies, the tool takes the uncertainty of the unwanted occurrence of a major accident into account through the usage of a so-called ‘disproportion factor’. Compared with existing software, the CESMA tool is innovative by striving for an as-accurate-as-possible picture of costs and benefits of major accident prevention, and taking the uncertainties accompanying disastrous events into consideration. Furthermore, an illustrative example of CESMA is presented in the paper.  相似文献   
85.
Objective: India has been slow in implementing a central emergency medical services (EMS) system across the country. “108 services” is one of the most popular services that is functional under the public–private partnership model. Limited available literature shows that despite access to services, many traffic crash victims are transported using private vehicles. The objective of this study is to understand the effectiveness of 108 services from a traffic safety perspective.

Method: A questionnaire survey is conducted to understand the awareness of EMS and their function. Using traffic-related fatalities as the dependent variable, a fixed effect panel data model is developed to analyze the effectiveness of the 108 services in improving the traffic safety.

Results: The results from the survey show that, in general, people are not aware of the 108 services. A majority of the population prefers taking victims to the hospital using their personal vehicles or any other vehicles available compared to calling an ambulance. Results from panel data analysis show that despite having an efficient system, these services failed to make significant improvement in the safety of road users in the states in which their services were subscribed.

Discussion: The lack of awareness of an important safety service is alarming. This could be a major reason for lower utilization of 108 services for transporting victims of traffic crashes. This article shows the importance of having efficient awareness campaigns to improve the efficiency of any similar programs that are aimed to enhance the safety of a region.  相似文献   

86.
Studies on selective demolition (also named deconstruction) in the past few years have produced some high quality economic, material and environmental information. Economic data, however, varies considerably between regions since local conditions strongly influence labour costs, tipping fees and/or market prices for recovered materials. Regional financial and regulatory constraints will bind the economic viability of conventional and selective demolition choices, which are essentially economic in a free market. Given this, the present study evaluates the economic implications of the two demolition types by analyzing a case study in Portugal. A few scenarios are considered, based on possible waste management options, some of which favour selective demolition over the conventional type.  相似文献   
87.
以JL污水处理厂设备管理优化过程为例,充分吸取LCC,TPM中的先进思想,以设备运行可靠性及设备维护经济性为追求目标,建立了设备管理优化体系。流程体系上,通过建立作业指导文件,建立标准化维修程序,对于操作过程及时进行记录,建立可视化、可追溯的管理方法;指标体系上,根据设备重要性及运行状况,确定设备风险指数,分级管理;建立控制指标,并动态调整;管控体系上,建立设备“户口”,对设备的维护、保养、使用等信息进行全面登记;考核设备维护的全面性、及时性、可靠性、合规性;重视设备维护的预计与预警;技术体系上,通过设备监测仪器的使用,对设备运行状况定量化。通过不断推进设备预防性维护工作,设备完好率不断提升,仪表完好率从2016年的97.34%,96.55%水平,分别提升至99.08%,98.72%;维护费用也保持在较低水平,检修费与资产比例在实施的前两年分别降至1.49%,0.85%,实现了污水处理厂节能降耗及运行可靠性的强化。  相似文献   
88.
This paper assesses the private and social profitability of current strategies for managing processionary moth (Thaumetopoea pityocampa) in Portuguese pine forests, looking at economic and environmental costs and benefits. Costs include the expenses for forest treatment and the social costs of threats to human health (dermatitis amongst others); benefits are assessed in terms of both revenue and social benefits such as carbon fixation and recreation. The evaluation was done using Cost Benefit Analysis (CBA) as an analytical framework. While this tool is currently applied to forest and environmental assessment and specific applications to pest management strategies are to be found in agricultural economics, rather few attempts have been made in the field of forest pest management. In order to assess and compare with--without options, a case-study was analysed for the Setúbal Peninsula, south of Lisbon, an area where extensive stands of maritime pine (Pinus pinaster) grow. The exercise has shown that CBA can be a valuable tool for assessing the economic and social profitability of pest management. The results demonstrate that the loss of revenues in the no-management option is not sufficient to make pest management profitable for private forest owners in the short-term. Conversely, a social profit is gained as pest management minimizes health risks for humans and avoids possible recreational losses.  相似文献   
89.
Circulating levels of testosterone in adults have mainly evolved as a consequence of selection on males for increased levels, while levels of circulating testosterone in females may be an indirect consequence of selection on males. A review of the literature revealed that intense directional selection for high levels of circulating testosterone in birds is likely to be mainly due to direct selection on males. A comparative study of testosterone levels in birds revealed a strong positive relationship between peak testosterone levels in adult females and peak levels in males. The slope of this relationship was significantly less than unity, implying that the testosterone levels in females have been reduced in species with high levels in males. An analysis of the order of evolutionary events suggested that peak concentration of testosterone in females changed after peak concentrations of testosterone in males. Females in colonial species of birds had significantly higher circulating peak testosterone levels compared to females of solitary species, and relative levels after controlling for the effects of peak levels in males were also larger, suggesting that any costs of high testosterone levels in females are particularly likely in colonial birds. Direct selection on male circulating testosterone levels may increase the costs that females incur from high testosterone titers. For example, high female levels may negatively affect ovulation and laying and may also affect the levels of testosterone that females deposit in their eggs and hence the exposure of pre- and post-hatching offspring to testosterone. This in turn may affect not only offspring behavior, but also offspring development and the trade-offs between growth, development of immune function, and behavior in offspring.  相似文献   
90.
从经济学和委托代理理论出发构建非国有企业和国有企业环境污染行为产生的成本-收益决策模型,分析了污染行为产生的根本动因,并据此提出控制企业环境污染行为有效可行的政策。  相似文献   
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