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201.
In contingent valuation, despite the fact that many externalities manifest themselves as costs to some and benefits to others, most studies restrict willingness to pay to being non‐negative. In this paper, we investigate the impact of allowing for negative, zero and positive preferences for prospective changes in woodland cover in two UK national parks, the Lake District and the Trossachs. An extended spike model is used to accomplish this. The policy implications of not allowing for negative values in terms of aggregate benefits are also investigated, by comparing the extended spike model with a simple spike making use of only zero and positive bids, and a model which considers positive bids only. We find that ignoring negative values over‐states the aggregate benefits of a woodland planting project by up to 44%.  相似文献   
202.
This paper proposes a nonparametric procedure to estimate market power for first‐price auction data and applies the procedure to cattle procurement markets. Most previous studies have used parametric methods, which require specific functional forms for retail demand, input supply and processors’ cost equations. However, researchers often find that market power estimates from parametric methods are sensitive to the choice of functional forms and specifications. An application to data from cattle procurement experiments shows that our nonparametric approach greatly outperforms commonly used parametric methods in estimating the degree of market power. While parametric estimates are sensitive to functional form specification and are at least 90% smaller than ‘true’ market power indices, estimates from our nonparametric procedure deviate from the actual value by no more than 25%.  相似文献   
203.
The paper outlines EU policy on bioenergy, including biofuels, in the context of its policy initiatives to promote renewable energy to combat greenhouse gas emissions and climate change. The EU’s Member States are responsible for implementing EU policy: thus, the UK’s Renewables Obligation on electricity suppliers and its Renewable Transport Fuel Obligation and road‐fuel tax rebates are examined. It is unlikely that EU policy is in conflict with the WTO Agreement on Agriculture or that on Subsidies and Countervailing Measures, but its provisions on environmental sustainability criteria could be problematic.  相似文献   
204.
This paper examines market integration between fish species in Europe, taking international market integration into account. Based on Juselius (2006) , market integration is found both on the fresh and frozen markets. The Law of One Price is in force on the fresh market within the segments of flatfish and pelagic fish. Assuming transitivity, a loose form of market integration is identified between 13 fresh and seven frozen fish species, and the relative prices are found fairly stable. The policy implication is that catch limitation measures implemented through the Common Fisheries Policy have limited and conditional effects on prices, because of the large size of the market and varying market integration. Therefore, many fishermen are not ‘compensated’ by price increases as a result of catch limitation measures.  相似文献   
205.
This article assembles the results of three multicountry surveys on variety performance and adoption patterns to measure the impacts of maize research in West and Central Africa from 1981 to 2005, and uses cost data since 1971 to compute social rates of return on public investments in maize research in the region. Adoption of modern varieties increased from less than 5% of the maize area in the 1970s to about 60% in 2005, yielding an aggregate rate of return on research and development (R&D) investment of 43%. The estimated number of people moved out of poverty through adoption of new maize varieties rose gradually in the 1980s to more than one million people per year since the mid 1990s. Over half of these impacts can be attributed to international maize research at IITA and CIMMYT. The article concludes with a discussion of strategic options to enhance the impacts of maize research in the region.  相似文献   
206.
Plant-based precision nitrogen fertilizer application technologies have been developed as a way to predict and precisely meet nitrogen needs. Equipment necessary for precision application of nitrogen, based on sensing of growing wheat plants in late winter, is available commercially, but adoption has been slow. This article determines the expected profit from using a plant-sensing system to determine winter wheat nitrogen requirements. We find that plant-sensing systems have the potential to be more profitable than traditional nonprecise systems, but the existing system simulated was roughly breakeven with a traditional system.  相似文献   
207.
朱宏霞 《现代经济》2009,(10):98-99
根据功率超声工艺制备A356铝合金半固态浆料实验结果,探讨在功率超声场作用下,A356铝合金半固态凝固过程中初生α-AL相细化和球化的机理。从合金的微观结晶过程描述了浆料中的形核和晶体的长大在超声场作用下的改变,提出了超声效应对合金凝固过程的综合影响。  相似文献   
208.
人们大都认为杨宪益所译《红楼梦》中“Manproposes,Heavendisposes”一句谚语忠实传达了源语文化内涵。通过综合分析关键词Heaven在英语中的文化内涵以及英语本族者的语感证实,杨完益和戴乃迭用Heaven一词并没有像众多论者所认为的那样忠实地传达了源语中的文化内涵。  相似文献   
209.
在温度采样系统中,经常遇到单片机A/D引脚不够的情况,现以CD4052为基础,把软件操作系统分时复用的思想应用到单片机编程中,结合CD4052选通不同的通道,实现较少A/D引脚采样多处温度点的功能。  相似文献   
210.
The stabilization of global climate presents one of the most complex problems in public good provision the world has faced. Continuation of “business as usual” policies, leading to warming of more than 2 degrees over the next year, will produce significant damage to agricultural systems and catastrophic damage to the natural ecosystems that ultimately support agriculture. The best solution to the public goods problem is a “contract and converge” agreement in which the ultimate outcome is a common global entitlement to CO2 emissions per person.  相似文献   
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