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101.
The standard approach to non-parametric bivariate density estimation is to use a kernel density estimator. Practical performance of this estimator is hindered by the fact that the estimator is not adaptive (in the sense that the level of smoothing is not sensitive to local properties of the density). In this paper a simple, automatic and adaptive bivariate density estimator is proposed based on the estimation of marginal and conditional densities. Asymptotic properties of the estimator are examined, and guidance to practical application of the method is given. Application to two examples illustrates the usefulness of the estimator as an exploratory tool, particularly in situations where the local behaviour of the density varies widely. The proposed estimator is also appropriate for use as a pilot estimate for an adaptive kernel estimate, since it is relatively inexpensive to calculate.  相似文献   
102.
Abstract Many race-specific differences in health outcomes that have been observed in previous research have been attributed to class and racebased group differences which either facilitate or constrain health opportunities and behaviors. These include such variables as different rates of poverty, health insurance coverage, and access to medical care. However, these relationships have been inadequately examined in rural communities where minority status may be even more detrimental to health than in urban areas, due to various constraints on access to health care. We present an analysis that assesses the effects of community, family structure, sociodemographic, and medical care variables on self-reported health status among Hispanics, Mrican Americans, and non-Hispanic whites in six rural communities in Florida. Community structural characteristics had a significant effect on self-reported health, as did some of the measures of how respondents “experience” community. These relationships held even when other sets of variables were added to the models. Family/household characteristics and sociodemographic and medical care variables were less important in explaining self-reported health status. These findings suggest that community continues to be important in explaining differences in health status in rural areas.  相似文献   
103.
Abstract Environmental social scientists have recently begun to use the term 'forest transition' to describe how forest cover changes as economic development occurs in nations. The hypothesized transition occurs as follows. An initial surge in economic activity in impoverished societies spurs deforestation, but as economic activity continues to intensify and cities grow larger, a 'turnaround' occurs, and deforestation gives way to reforestation. This paper uses cross-national data from five successive surveys of world forest resources to assess this empirical claim. A turnaround in forest cover trends does occur in a significant number of nations. The paper also evaluates two explanations for the turnaround, a wood scarcity hypothesis derived from microeconomic theory and an industrialization hypothesis linked to central place theory. It finds period specific support for the industrialization hypothesis. The paper concludes with a brief discussion of the implications of these findings for proposals to alleviate the biodiversity crisis through programs of reforestation.  相似文献   
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Beyond the theoretical basis for integration, three core considerations stand out as the primary reasons for pursuing integration from a physician's perspective. In the authors' experience, the ability to make a case for physician integration stands or falls based on the ability of the integrated delivery system to address these considerations: Gain greater access to capital; develop human resources with talents in managed care and the full spectrum of care services; and sustain an information infrastructure. This article explores the lessons learned in pursuing physician integration.  相似文献   
106.
"While several studies (in both Turkish and English) have been made on migration to the Ottoman Empire from the Caucasus and the Balkans during the nineteenth century...very little systematic and comprehensive research on migration has been undertaken on the period since the establishment of the Turkish Republic. This article, which aims to partially fill the gap, is divided into three parts: the issue of national refugees (refugees of Turkish origin) in relation to Turkey's overall refugee policy; Turkey's policy towards national refugees; and the volume and causes of refugee migration to Turkey since 1945." (SUMMARY IN FRE AND SPA)  相似文献   
107.
The need for long-term care is driven both by the growth of the elderly population and changes in the age relations of morbidity, disability, and mortality. Data show these relations changed in the U.S. elderly population from 1982 to 1989. Chronic disability prevalence declined between the 1982 and 1989 U.S. National Long Term Care Surveys. Among those impaired, many persons using personal assistance to meet their needs shifted to the use of assisted housing and special equipment. The relation of these trends to other changes--such as the increasing educational level of the elderly population--is examined to estimate how future changes in disability and morbidity may affect the demand for long-term care. Disabilities at specific times as well as their transition rates were examined to determine how long individuals need long-term care. The analyses suggest that, while the amount of long-term care services needed will increase rapidly, the types and amounts of services used by the U.S. elderly population will undergo significant change.  相似文献   
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"The purpose of this article is to place Chinese labor migration from agriculture within the context of the literature on labor mobility in developing countries by comparing it to undocumented Mexican migration to the United States. The similarities fall within three general areas: the migration process, the economic and social position of migrants at their destination, and the agrarian structure and process of agricultural development that has perpetuated circular migration. The last section of the article draws upon these similarities, as well as differences between the two countries, to generate predictions concerning the development of labor migration in China."  相似文献   
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