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991.
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993.
Past, current and projected future population growth is outlined. Barring a calamitous pandemic, a further increase in the world’s population from 7 to between 8.8 and 10 billion by mid-century is unavoidable. This increase is driven by high fertility in sub-Saharan Africa whose population is forecast to more than double in the next 40 years and by a modest rise of 23 % in Asia’s huge population. Beyond mid-century, the range of plausible demographic destinations widens; much depends on fertility rates in the next few decades because they will determine the number of potential reproducers in the second half of the century. Vigorous promotion of family planning, particularly in Africa, is crucial to achievement of population stabilisation. Unchanged fertility implies a global population of 25 billion by the end of the century. In the next few decades the contribution of human population growth to global environmental change is moderate, because nearly all growth will occur in poor countries where consumption and emission of greenhouse gases is low. The implications for food production, and thereby water consumption, are greater. Much of the future need for food will be driven by increased numbers rather than changing diets. Loss of bio-diversity and natural habitats, degradation of fragile eco-systems due to over-exploitation and aquifer deletion are likely consequences.  相似文献   
994.
995.
Behavioral norms consist of two components: a cognitive component of obligation that is the memory repository of social standards, and an emotional component of sanctions that are the feelings and physiological states that result when actual behavior is consistent or not consistent with the obligation. This article analyzes the cognitive and emotional components of norms identified in three studies of behaviors (littering, controlling dogs while cross country skiing, and bikers and skaters warning when passing) in outdoor recreation settings. All three studies provide data on obligations to behave a particular way and internal and informal sanctions for correct or incorrect behavior. Obligations for all the behaviors were highly crystallized and were not statistically different. Internal sanctions were shame and guilt, and informal sanction was embarrassment. The intensity of the norms was determined by summing individuals' responses for shame, guilt, and embarrassment. The power and prevalence of the norms were determined by cross tabulating obligations by intensities. Intensity, power, and prevalence were very high for littering and failing to control your dog while cross country skiing, but were very low for skaters and bikers failing to warn when passing slower users on a multiple use trail. Measuring sanctions is shown to be critical to determining the intensity, power, and prevalence of behavioral norms. Suggestions are given for ways to include sanctions in studies of social and environmental condition norms.  相似文献   
996.
In this article two high school economics teachers describe several teaching techniques that have proven successful in their school. The use of a team approach is briefly explained, and the importance of student motivation is stressed. Among the methods included are skits, plays, the use of video tapes, simulations and games, and the analysis of important economic problems. The means by which the instructors are evaluating their course are set forth, with evidence that the experience helps to destroy commonly held myths about economics and greatly improves student understanding of basic principles.  相似文献   
997.
To study the house price dynamics in China, this paper extends the traditional life-cycle model by incorporating land supply, regime shifts and government regulation factors. The models are estimated with an error correction framework using quarterly data from 2000 to 2007 in Beijing. The conclusions are as follows. (1) There exits a stable co-integration relationship between house price and fundamentals; land supply and financial regimes are also important determinants of long-run equilibrium house prices. (2) Short-run dynamics depend on changes of fundamentals and the adjustment process of housing market. Land supply has a significant impact on house price fluctuations while demand factors such as user costs, income and residential mortgage loan have greater influences. The adjustment speed of real house prices to the long-run equilibrium has been reduced significantly since 2005 which means exogenous shocks can cause prolonged deviation of real house prices from the equilibrium level.  相似文献   
998.
The gravity equation is usually employed by researchers in the field of international trade to explain the growth of a country’s imports and exports volume, especially the manufactured goods. But in China, variables in the model, such as exchange rate, tariff, transportation cost, and spatial distance etc., are not sufficient to explain the riddle of China’s growth in trade volume. In fact, this growth in China’s trade volume is owing to the disintegration of production in the process of economic globalization, to the multinational corporations’ (MNC) vertical outsourcing of their manufacturing processes and procedures, and to the timely readjustment of Chinese enterprises on their strategies of participating in the international intra-product specialization. In this paper we establish an equilibrium model of intra-product specialization dominated by MNCs, and do some empirical tests on the growth in trade volume in China by using the variables including technological conditions of trade, similarity of economies, policy conditions of trade, disintegration of production and level of per capita capital equipment. The empirical results support our basic judgments.  相似文献   
999.
卫生技术评估(Health technology assessment,HTA)是对卫生保健技术应用所产生的短期与长期结果进行检验的一种政策研究形式。评估的内容包括安全性、有效性、患者自报结果、现实效果、成本和成本一效果以及社会、法律、伦理和政治影响等。  相似文献   
1000.
Choices of television programs is viewed as a process of deciding among a set of alternative goods with zero prices. A choice model can thus be based purely on individuals' preferences for various characteristics of a set of shows available, incorporating the option of not watching if all shows are too dissimilar to these desires. The shows are first grouped according to salient characteristics and a preferred value for each characteristic is estimated for each potential viewer. A perceived position of each show is similarly estimated and watching is shown to decline as similarity between preferred show and available alternatives declines. The choice model predicts show choice better than simpler models based on aggregate audience measures or on network loyalty, but the explanatory power is weak; some suggestions for improvement are made.  相似文献   
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