Background. The present investigation was designed to obtain an absolute measurement of myocardial blood flow and of its transmural distribution in ischemic heart disease and idiopathic dilated cardiomyopathy and to provide a reference standard for cardiac imaging in nuclear cardiology.Methods and Results. Regional myocardial blood flow and its transmural distribution were estimated by the reference microsphere method in eight patients with idiopathic dilated cardiomyopathy (n=4) or

Under the current family planning policy in China, the criterion for evaluating all parties involved in the birth planning system provides an incentive for everyone to see that the policy is met, either in reality through strict enforcement of family planning regulations, or statistically through manipulation of statistical records. We investigate underreporting of births in four rural counties of northern China, using data from a 1992 sample survey featuring a reproductive history. To clarify the mechanisms of underreporting, we focus on the ways in which reporting errors may affect the distribution of first births by time since marriage. The results of our investigation suggest that in three of the four counties, first-birth intervals are lengthened by underreporting of girl babies and by replacing them with second births reported as first births.

Respondent-driven sampling (RDS) is a method for recruiting “hidden” populations through a network-based, chain and peer referral process. RDS recruits hidden populations more effectively than other sampling methods and promises to generate unbiased estimates of their characteristics. RDS’s faithful representation of hidden populations relies on the validity of core assumptions regarding the unobserved referral process. With empirical recruitment data from an RDS study of female sex workers (FSWs) in Shanghai, we assess the RDS assumption that participants recruit nonpreferentially from among their network alters. We also present a bootstrap method for constructing the confidence intervals around RDS estimates. This approach uniquely incorporates real-world features of the population under study (e.g., the sample’s observed branching structure). We then extend this approach to approximate the distribution of RDS estimates under various peer recruitment scenarios consistent with the data as a means to quantify the impact of recruitment bias and of rejection bias on the RDS estimates. We find that the hierarchical social organization of FSWs leads to recruitment biases by constraining RDS recruitment across social classes and introducing bias in the RDS estimates.

We used a new conceptual framework that integrates tenets from health economics, social epidemiology, and health behavior to analyze the impact of socioeconomic forces on the temporal changes in the socioeconomic status (SES) gap in childhood overweight and obesity in China. In data from the China Health and Nutrition Survey for 1991 to 2006, we found increased prevalence of childhood overweight and obesity across all SES groups, but a greater increase among higher-SES children, especially after 1997, when income inequality dramatically increased. Our findings suggest that for China, the increasing SES gap in purchasing power for obesogenic goods, associated with rising income inequality, played a prominent role in the country's increasing SES gap in childhood obesity and overweight.