Generic tobacco use among four ethnic groups in a school age population

The prevalence of overall or "generic" tobacco use among Hispanic, white, Black and Asian youths in grades four, seven, ten and twelve was compared in San Diego, California (n = 4980). Significant differences in generic tobacco use between ethnic groups were found in the 4th, 10th and 12th grades, but were greatest in the 10th grade. Only white youths demonstrated a sharp increase in regular tobacco use (once a month or more) between 7th and 10th grade. Overall, the prevalence of regular use was highest among whites (25.8%), followed by Hispanics (19.7%), Blacks (17.6%) and Asians (12.6%). Marijuana, alcohol, and other drug use explained approximately 40 percent of the variance in tobacco use in each ethnic group. Other predictors varied by ethnicity and included socioeconomic status, happiness of student, strictness of parent, adult tobacco use at home, accessibility to marijuana, and gender.     

Geographically indirect immigration to Canada: description and analysis

"This article is concerned with geographically indirect immigration to Canada over the period 1968-1988. A geographically indirect immigrant is an individual legally admitted to Canada whose country of last permanent residence differs from country of birth. Records maintained by Employment and Immigration Canada on every immigrant legally admitted over the period were used in the study. Relative to geographically direct immigrants, geographically indirect immigrants tend to be older, more educated, and more highly skilled. Moreover, if they were not born in an English or French speaking country, indirect immigrants are more likely to speak English and/or French capably than direct migrants born in such countries. The study also contains bivariate logit estimates of a model of geographically indirect Canadian immigration. This model suggests that indirect migrants tend to be influenced by personal characteristics (age, sex, marital status, occupation, language ability), as well as by various characteristics of the country of birth (distance from Canada, income level, political conditions)."     

《相对论电子学》教学难点CAI

针对《相对论电子学》教学中所涉及到的主要难点问题,如：自由电子激光的物理机制;谱波自由电子激光的物理机制;虚阴极振荡器的物理机制;任意倾角斜旋转轴准光腔回旋管（ＡＱＣＯＲＡＡ）的物理机;电子回旋脉塞的饱和机理－相位捕获等;以非线性理论为基础,模拟电子与波互作用从线性调制到非线性饱和的演化过程,以图形方式实时动态显示了电子的群聚和换能,形成了教学软件ＲＥ—ＣＡＩ。     

Resource allocations to the aged according to greatest social need

The purposes of the study reported on in this article were: (a) to explore the measurement of social need among the elderly, and (b) to develop an appropriate method for including social need in funding allocation procedures. Interview responses from over 4,000 randomly selected elderly persons were used to identify the demographic correlates of those having the most restrictions in their every-day lives. Procedures for intrastate allocations were developed using variables suggested by the Older Americans Act and by research to explain variance in activities of daily living. Variables tested for the model were: age, income, living arrangement, gender, ethnicity, area of residence, occupation, hospitalization, years in the neighborhood, language at home, and utilization of senior services. Prediction formula weights were adjusted (magnitude of beta i/sigma magnitude of beta i) to allocate resources to the proportions of 10 "high-need" groups residing in each planning area: the population aged 75 and older, the proportion of hospital discharges of elderly patients, elderly females, elderly non-Caucasians, the elderly not completing high school, elderly farm workers, elderly urban residents, a proportion for participation in senior services, for low-income elderly persons, and for the elderly not living with their spouses. Compared to current systems, the proposed procedure provides a closer fit to the actual needs of the elderly.     

Branch plants and poverty in the American South

An alternative to the widely accepted hypothesis that big business has a negative impact on community welfare is tested with data from 445 nonmetropolitan counties in the American South. We argue that the appropriate counterhypothesis is not that branch plants have a positive impact on community welfare, because that and similar formulations simply perpetuate the nonsociological approach of the early hypotheses. An interaction formulation that sees community structure as mediating the impact of branch plants better explains differentials in our three criteria of welfare—per capita income, percent below the poverty line, and infant mortality. This explanation predicts positive welfare when pluralism and urbanization are high and branch plants are frequent, and lower welfare when one or both of these is low. Tests using discriminant analysis support the interaction hypothesis while providing little evidence for either the direct positive or negative impact hypotheses.     

Factors associated with the timing and duration of the leaving-home stage of the family life cycle

Summary Based on empirical age distributions of sons and daughters leaving home, an examination is made of the theoretical effect of three factors - the sex composition of the family, the interval between births, and their reasons for leaving home - on the dynamics of the leaving-home stage in the life cycle of two-child families. Consideration is given to four measures, the timing of the beginning and end of the leaving-home stage, its duration, and the ratio of the length of the leaving-home stage to the length of the childbearing stage. The outstanding feature of the leaving-home stage is that a second child may leave home before its older sibling, described as the 'crossing-over effect'. For Australian data, factors contributing to the variation in experience between families include the fact that sons generally leave home at an older age than daughters, and that children leaving home for different reasons leave at different ages. Brief reference is made to the relationship between the leaving-home stage and the starting-work stage, and to the limitations of a theoretical analysis.     

Bayesian adaptive two-stage design for determining person-time in Phase II clinical trials with Poisson data

Adaptive clinical trial designs can often improve drug-study efficiency by utilizing data obtained during the course of the trial. We present a novel Bayesian two-stage adaptive design for Phase II clinical trials with Poisson-distributed outcomes that allows for person-observation-time adjustments for early termination due to either futility or efficacy. Our design is motivated by the adaptive trial from [9 V. Sambucini, A Bayesian predictive two-stage design for Phase II clinical trials, Stat. Med. 27 (2008), pp. 1199–1224. doi: 10.1002/sim.3021[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]], which uses binomial data. Although many frequentist and Bayesian two-stage adaptive designs for count data have been proposed in the literature, many designs do not allow for person-time adjustments after the first stage. This restriction limits flexibility in the study design. However, our proposed design allows for such flexibility by basing the second-stage person-time on the first-stage observed-count data. We demonstrate the implementation of our Bayesian predictive adaptive two-stage design using a hypothetical Phase II trial of Immune Globulin (Intravenous).     

Modified stages of acquisition of gateway drug use: a primary prevention application of the stages of change model

The purpose of the study was to identify the stages of acquisition of gateway drugs in fourth, fifth, and sixth graders. The Stages of Acquisition model is a primary prevention application of the Stages of Change model. The subjects in the study were 811 students from seventeen elementary schools in Arkansas and Missouri. The instrument elicited information regarding the stages of acquisition and individual self-reported drug use. The data were analyzed using frequency, distribution, discriminant analysis, and correlation analyses. Stage placement was confirmed using a series of drug use measures. Results confirmed the existence of discrete stages of acquisition. Results supported the concept of gateway drugs in that subjects indicated they had progressed further through the stages of acquisition of alcohol use than through the stages of acquisition of cigarettes use, smokeless tobacco use, or marijuana use.     

Toward a pragmatic program for critical urban ecology

Our essay responds to the critique of Dooling et al. (Urban Ecosystems in press, 2007) of our previously published article “Goal attainment in urban ecology research: a bibliometric review 1975-2004 (Young and Wolf, Urban Ecosystems, 9:179–193, 2006). We identify our critics’ concerns as rooted in a project of deconstruction of scientific inquiry and a redefinition of the boundaries separating academic disciplines from each other and science from society. While we identify important differences with our critics, we largely support this critical project, as evidenced by our previously published empirical research. In exploring the relationship between critical and positivist approaches to urban ecology research and how we might work toward an integration of nature and society in thought and action, we defend pragmatic approaches to empirical research as well as disciplinary projects as legitimate and essential elements of urban ecology research. We argue in favor of theoretical and methodological pluralism. Rather than define urban ecology through exclusionary projects that would limit the scope and significance of urban ecology research, we reaffirm our call for diverse sets of actors inside and outside university settings to engage and support each other in order to develop and strengthen analysis and pursuit of sustainability.