Problematic Progress in Asia: Growing Older and Apart

The purpose of this article is to describe the demographic dynamics in 14 Asian countries. The foreseen impacts on economic growth, income disparity, social stability, pension programs, retirement, health care insurance, and labor market are presented. Public policy recommendations are delineated.     

Predicting continued use of marijuana among adolescents: the relative influence of drug-specific and social context factors.

Most research on the determinants of adolescent drug use has focused on predictors of either initiation or current use. Little attention has been given to the determinants of continued use of drugs after initiation, even though some researchers have found that the consequences of continued use are more serious than those associated with experimental or occasional use. In this study, a longitudinal sample of 456 secondary and high school students who had already tried marijuana was used to examine the determinants of continued use of marijuana. Nearly 38 percent of those who had tried marijuana continued using, according to the definition operationalized in this study. Potential predictor measures were grouped in a drug-specific domain and a social context domain, and their effects on continued use, controlling for background characteristics, were examined in logistic regression models. Results showed that only the drug-specific domain had a statistically significant effect on the likelihood of continued use. Students who felt that the adverse physical and psychological effects of marijuana were not very important reasons for discontinuing use and those who had gotten stoned during their experimental stage of use were the most likely to continue use after initiation. The results suggest that the perceived physical and psychological effects of the drug are more important determinants of continued use than are social factors or benefits related to use. Any relationships between social factors and continued use are mediated by the perceived effects and risks of the drug.     

Muscle-power quality: does sex or race affect movement velocity in older adults?

To determine sex and race differences in muscle power per unit of muscle contraction, knee-extensor muscle power normalized for knee-extensor muscle volume was measured in 79 middle-aged and older adults (30 men and 49 women, age range 50-85 years). Results revealed that women displayed a 38% faster peak movement velocity than men and African Americans had a 14% lower peak movement velocity than Whites of a similar age when expressed per unit of involved muscle (p < .001). As expected, men exhibited greater knee-extensor strength and peak power per unit of muscle than women, but women had a faster knee- extension movement velocity per unit of muscle than men at the same relative strength level. Moreover, African Americans had greater knee-extensor muscle volume than Whites but exhibited lower knee-extensor strength and lower movement velocity per unit of muscle when tested at the same relative strength levels.     

Time series analysis of stratospheric ozone

Time series analyses of monthly average total ozone measured at 37 stations throughout the world were used to estimate the extent to which the average ozone trend correlates with the depletion curve hypothesized as due to chlorofluorocarbons (CFCs). Statistical characteristics of stations in the ensemble were used to help define appropriate model and station selection criteria. The maximum likelihood procedure developed herein estimates the weighted average trend, its. variance, and the intra- and inter-station variance components of the trend. Correlations among trends at different stations are also taken into account. The models were subjected to much checking and criticism. Variations in statistical methodology are used to show that the results are insensitive to details of the model selection criteria. The method does not discriminate well between the hypothesized CFC trend and a linear trend. The trend estimates represent the sum of all long-term global effects. The variance includes all effects that differ from station-to-station. The estimated trend and 2α limits for 14 stations with 20-year records (1958-79) is an ozone increase through 1979 of (1.5+1.0) percent. At the 23 stations with shorter records, the trend is (1.0=1.7) percent. It is concluded that no significant depletion in stratospheric ozone has occurred from any cause through the end of 1979.     

First order autoregressive time series with negative binomial and geometric marginals

In this paper we present first order autoregressive (AR(1)) time series with negative binomial and geometric marginals. These processes are the discrete analogues of the gamma and exponential processes introduced by Sim (1990). Many properties of the processes discussed here, such as autocorrelation, regression and joint distributions, are studied.