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241.
Abstract . Six attempts to measure the deterrence effect of law enforcement on certain criminal activities, as well as one by the author, have produced no clear, unequivocal evidence to support the belief that increased public expenditures on law enforcement have a deterrent effect on such activity. Yet the effect may exist. Further research into the measurement of the variables crime and enforcement and upon the nature of the relationship between them must be carried on before definite conclusions can be reached about the existence of the deterrence effect.  相似文献   
242.
Beef cattle producers were surveyed in Texas and Nebraska to investigate perceptions of sources of risk, the effectiveness of risk management strategies, and interest in further risk management education, particularly production risk, using probit analysis. Important decision variables identified are age, prior use of risk management tools, previous attendances of risk management education, and risk aversion. Severe drought and cattle price variability are identified as primary risk factors with potential to affect farm income. Extremely cold weather and disease are of less importance. Understocking pasture and storing hay are perceived most effective as risk management options.  相似文献   
243.
This article revisits a conventional wisdom that inorganic fertiliser use across sub‐Saharan Africa is too low. This expectation that more farmers should be using inorganic fertiliser, and at higher rates, implies it is profitable to use rates higher than observed if farmers are rational expected profit maximisers. We obtain consistent estimates of the effects of applied nitrogen on rice production. We find the yield response to applied nitrogen to be low in the main rice growing farming system. Farmer behaviour is not inconsistent with expected profitability which is limited by a low yield response to applied fertiliser, high transportation costs, and low selling prices for rice in rural areas. In particular, we do not find any farmers for whom applied nitrogen is profitable that are not using fertiliser in the study sample for each of our survey years (2010 and 2012).  相似文献   
244.
The United States (US) exports more than US$6 billion in agricultural commodities to the European Union(EU) each year, but one issue carries the potential to diminish this trade: use of biotechnology in food production. The EU has adopted more stringent policies towards biotechnology than the US. Understanding differences in European and American policies towards genetically modified (GM) foods requires a greater understanding of consumers’ attitudes and preferences. This paper reports results from the first large‐scale, cross‐Atlantic study to analyse consumer demand for genetically modified food in a non‐hypothetical market environment. We strongly reject the frequent if convenient assumption in trade theory that consumer preferences are identical across countries: the median level of compensation demanded by English and French consumers to consume a GM food is found to be more than twice that in any of the US locations. Results have important implications for trade theory, which typically focuses on differences in specialization, comparative advantage and factor endowments across countries, and for on‐going trade disputes at the World Trade Organization.  相似文献   
245.
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   
246.
This paper is concerned with the relationship between the planning of settlements and health. It gives a brief introduction to the issues before summarising the evidence in relation to a range of topics, concluding with some more speculative thoughts on likely future findings.Modern planning was invented in response to inhumane living conditions in 19th century cities. But in the last century the connection was lost. Only now, with concerns over climate change and obesity, is there beginning to be the realisation that the physical environment is an important determinant of health.The paper uses a particular model of this relationship based on eco-system and health determinants theories to structure the review of evidence. The review covers: lifestyle choices in relation to physical activity and diet, mental well-being and community, the local economy and income, health inequalities and strategic land use transport planning, pollution and urban form, and finally impacts on global ecology.There is now a growing consensus that while personal factors are critical in determining health, the urban environment exacerbates or mitigates health and well-being outcomes.The level of active travel (walking and cycling) and outdoor recreational activity is strongly affected by accessibility to local facilities. Access to green, natural environments, and to local social networks, are factors in mental well-being. The wider sub-regional pattern of housing, economic development, land use and transport is a determinant of social exclusion and therefore health inequalities. It also affects health-damaging pollution, adaptability in the face of climate change and the level of carbon dioxide emissions.We have literally been building unhealthy conditions into many of our towns and cities. But comparisons with the best cities in Europe indicate that it is possible to reverse the less desirable trends. Success depends, however, on more radical policies of local authority control over land and finance than any political party has yet advocated. It also requires collaboration between the full range of powerful public and private organizations that influence the built environment.Future research is likely to further strengthen these conclusions. It will become much more obvious that planning for health and well-being is not only the NHS, but about creating a health-promoting physical, social and economic environment.  相似文献   
247.
248.
On Choosing Among House Price Index Methodologies   总被引:7,自引:0,他引:7  
This paper compares housing price indices estimated using three models with several sets of property transaction data. The commonly used hedonic price model suffers from potential specification bias and inefficiency, while the weighted repeat-sales model presents potentially more serious bias and inefficiency problems. A hybrid model combining hedonic and repeat-sales equations avoids most of these sources of bias and inefficiency. This paper evaluates the performance of each type of model using a particularly rich local housing market database. The results, though ambiguous, appear to confirm the problems with the repeat sales model but suggest that systematic differences between repeat-transacting and single-transacting properties lead to bias in the hedonic and hybrid models as well.  相似文献   
249.
250.
The contract cleaning industry has hitherto managed to avoid the establishment of collective bargaining machinery. Will this situation be remedied in the light of the N.B.P.I, report, pressure from the unions concerned and the T.U.C. ?  相似文献   
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