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Biofortification of maize with provitamin A carotenoids is a new approach to the alleviation of vitamin A deficiencies in Africa. Unfortunately these varieties are yellow or orange, while consumers generally prefer white. Consumer willingness to pay for yellow and fortified maize was compared in experimental auctions in three regions in Kenya. The premium that consumers are willing pay for fortified maize (24%) was higher than the discount they require to buy yellow maize (11%), and in one zone consumers prefer yellow. Yellow color is, therefore, not an impossible obstacle for biofortified maize, although it would clearly be easier to introduce this maize first in regions where yellow maize is currently grown.  相似文献   
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This paper develops a new test for speculative bubbles, which is applied to data for the Japanese yen, the German mark and the Canadian dollar exchange rates from 1977 to 1991. The test assumes that bubbles display a particular kind of regime-switching behaviour, which is shown to imply coefficient restrictions on a simple switching-regression model of exchange rate innovations. Test results are sensitive to the specification of exchange rate fundamentals and other factors. Evidence most consistent with the bubble hypothesis is found using an overshooting model of the Canadian dollar and a PPP model of the Japanese yen.  相似文献   
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Bob Quinn spent 20 years propagating an ancient Egyptian wheat variety that is generally known as Khorasan wheat. Bob trademarked his wheat variety using the brand name "Kamut®." Kamut® brand wheat contains some nutritional, health, and taste advantages over modern wheat varieties, but lacks some of modern wheat's agronomic advantages. Kamut® brand wheat is organically produced, and is used to make cereals, breads, cookies, snacks, pancakes, bread mixes, bulgur, pasta, and baked goods. Whole wheat products produced from Kamut® brand wheat are less bitter than those produced from modern wheat varieties. Europe represents approximately two-thirds of the market for this product.  相似文献   
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Distance functions are increasingly being augmented, with environmental goods treated as conventional outputs. A common approach to evaluate the opportunity cost of providing an environmental good is the exploitation of the distance function's dual relationship to the value function. This implies that the opportunity cost is assumed to be non‐negative. This approach also requires a convex technology set. Focusing on crop diversification for a balanced sample of 44 cereal farms in the East of England for the years 2007–2013, this paper develops a novel opportunity cost measure that does not depend on these strong assumptions. We find that the opportunity cost of crop diversification is negative for most farms.  相似文献   
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There have been repeated calls for a ‘new professionalism’ for carrying out agricultural research for development since the 1990s. At the centre of these calls is a recognition that for agricultural research to support the capacities required to face global patterns of change and their implications on rural livelihoods, requires a more systemic, learning focused and reflexive practice that bridges epistemologies and methodologies. In this paper, we share learning from efforts to mainstream such an approach through a large, multi-partner CGIAR research program working in aquatic agricultural systems. We reflect on four years of implementing research in development (RinD), the program’s approach to the new professionalism. We highlight successes and challenges and describe the key characteristics that define the approach. We conclude it is possible to build a program on a broader approach that embraces multidisciplinarity and engages with stakeholders in social-ecological systems. Our experience also suggests caution is required to ensure there is the time, space and appropriate evaluation methodologies in place to appreciate outcomes different to those to which conventional agricultural research aspires.  相似文献   
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Genetically modified (GM) crops are popular in many regions of the world, but their deployment in Africa is hindered by safety concerns and regulatory issues, although the continent is in dire need of boosting its food production. Although consumers' acceptance of GM food has been analyzed in many continents, no such studies have been conducted in Africa. Therefore, a survey of 604 consumers was conducted in Nairobi, Kenya, in 2003, to gauge consumers' awareness of GM crops, their willingness to pay (WTP) for GM food, and the factors that influence their WTP. Consumers' knowledge of GM crops was limited and only 38% of the 604 respondents were aware of GM crops. People in higher education and income groups were more aware than others. Regardless, people were generally appreciative of the technology, and a large majority (68%) would be willing to buy GM maize meal at the same price as their favorite brand. Consumers were, however, concerned about possible side effects, especially on the environment and biodiversity. WTP was estimated using a double‐bounded dichotomous choice model, and the mean WTP was found to be 13.8% higher than the average price of non‐GM maize meal. Perceptions of health risk, and ethical and equity concerns had a negative influence on the likelihood of purchasing GM maize meal, whereas trust in government to ensure food quality had a positive influence on WTP. People with at least some secondary education and those in the high‐income category were more likely to purchase GM maize meal at the same price. The study concludes that, because awareness is still low, appropriate communications are needed to involve the consumer in the debate. Consumers' acceptance in this study was high, but the research needs to be expanded to rural areas, where most consumers live, and other survey methods need to be explored.  相似文献   
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