BACKGROUND Hypertension (HTN) is a major cause of death in Chinese farmers. Remoteness from population centers may independently affect HTN prevalence and severity. METHODS We used random cluster sampling to select 27 villages in Yunnan province, China. Within each village, we randomly selected 50-80 men and women between the ages of 50 and 70 years. A total of 1,177 participants underwent in...

Megacities and other major population centers represent large, concentrated sources of anthropogenic pollutants to the atmosphere, with consequences for both local air quality and for regional and global atmospheric chemistry. The tradeoffs between the regional buildup of pollutants near their sources versus long-range export depend on meteorological characteristics which vary as a function of ...

The main interest in epidemic models stems from their use in uncovering certain qualitative features of epidemic processes. A deterministic model of a general epidemic in a population with an arbitrary number of separate population centers is presented. The mixing within each center is assumed to be homogeneous, and the usual threshold theorem holds for each population. The mixing between cente...

Arizona is a large state that has undergone profound population changes since the end of World War II. It has two major population centers (Phoenix and Tucson) that together account for approximately 75% of the state’s population. Much of the remaining population is found in small communities scattered throughout the state. There is a high Native American population, largely rural but with some...

CONTEXT Trauma centers benefit thousands of injured individuals every day and play a critical role in responding to disasters. The last full accounting of the number and distribution of trauma centers identified 471 trauma centers in the United States in 1991. OBJECTIVE To determine the number and configuration of trauma centers and identify gaps in coverage. DESIGN, SETTING, AND SUBJECTS I...

BACKGROUND The access to and growth of percutaneous coronary intervention (PCI) has not been fully explored with regard to geographic equity and need. Economic factors and timely access to primary PCI provide the impetus for growth in PCI centers, and this is balanced by volume standards and the benefits of regionalized care. METHODS AND RESULTS Geospatial and statistical analyses were used t...