Spatial Diffusion of the HIV/AIDS Epidemic: Modeling Implications and Case Study of AIDS Incidence in Ohio

This paper extends a compartmental epidemiological model for HIV transmission and AIDS incidence to include hierarchical and expansion spatial diffusion. An implication of the resultant model is that hierarchical diffusion causes the large infection growth rates of densely populated areas at the top of the central places hierarchy to “chain” down and dominate small local growth rates during the exponential-growth phase of the epidemic. Also, hierarchical diffusion causes a high transient growth rate in the first few years of a local epidemic. The spatial compartmental model fits observed AIDS incidence spatial diffusion patterns in Ohio reasonably well.     

Planning in the 1990s: An international agenda

This paper, originally presented to the AESOP‐ACSP joint conference in Oxford in 1991, stresses that both in Europe and in the US, there is a major difference for planning in the switch from boom to recession. During the 1990s a major challenge will be to find new ways of public‐private partnership in financing new urban infrastructure at a time when developer contributions — a major innovation of the 1980s — have dried up. This particularly applies to the European high‐speed train system — one critical element of which will run through the East Thames Corridor, one of Britain's major urban developments in the coming years. In the US, planners are likely to remain more locally focused, less internationally concerned, than in a Europe in which national barriers are rapidly eroding.     

试论人类身高的地域差异规律及其成因

人类身高高纬高于低纬,牧区高于农区、沿海高于内地、低海拔高于高海拔、城市高于农村、发达国家高于发展中国家。其主要原因是气温的高低、光照的多少和营养的差异。     

图们江“金三角”国际性城市体系发展构想

本文论述了图们江地区国际性城市体系建设的必要性,提出了城市体系等级结构、职能结构和空间结构的构建设想及管理原则,并初步估算了城市体系发展各项基础设施建设及投资规模。