韩天衡篆刻艺术解析

韩天衡是新时期中国篆刻界的领军人物,他对中国篆刻的继往开来起到了很大的作用。他的篆刻以胆心、腕力、心力相参,大刀阔斧、雄浑厚重,在刀法、布局、线条及边款诸方面都形成了自己鲜明的特色。     

离心泵叶轮半圆形切割方法

针对现有的传统叶轮切割方法的不足,提出了一种叶轮特殊切割方法——半圆形叶轮切割方法,利用CFD数值 模拟的方法,对多工况不同尺寸半圆形切割方案下的泵模型开展相关研究。结果表明,这种半圆形的叶轮特殊切割方法 可以改善泵外特性曲线,消除驼峰,还可以显著地提升泵的扬程性能指标;半圆形切割方案的最佳切割直径d为叶轮出 口宽度h,的0.4倍;此外,通过对流场流动特性的分析得出,半圆形叶轮切割方法之所以有显著效果,是因为切割后叶轮 出口及蜗壳处的压力梯度和速度梯度较低,速度和压力分布要比模型泵内的分布更均匀,使得泵内混合冲击损失变小。     

Parental Work Schedules and Child Overweight or Obesity: Does Family Structure Matter?

The authors used longitudinal data from the Fragile Families and Child Wellbeing Study (N = 5,482) to investigate whether maternal and paternal work schedules affect child overweight or obesity. They took the novel step of examining whether this effect is consistent for children living in different family structures. Findings from child fixed effects models suggest that the probability of child overweight or obesity was higher for children living with mothers who worked standard shifts at a primary job and nonstandard shifts at a secondary job compared to children living with mothers who worked a standard shift at a primary job only. Fathers' work schedules were not associated with child overweight or obesity. Unexpectedly, maternal standard shift work at a primary job and nonstandard shift work at a secondary job was associated with overweight or obesity only among children living with married biological parents.     

A longitudinal investigation of the role of violence prevention climate in exposure to workplace physical violence and verbal abuse

The temporal direction of the relationships between violence prevention climate and both physical violence and verbal abuse was investigated in a longitudinal study of newly graduated registered nurses. A sample of 126 nurses, recruited into the study while students, completed similar surveys at approximately 6 and 12 months after graduation that assessed violence prevention climate, physical violence, verbal abuse exposure, and strains of anger, anxiety, depression, and physical symptoms. Results showed that high values of Time 1 climate were associated with less likelihood of violence and abuse at Time 2 when prior exposure to violence and abuse was controlled. Furthermore, repeated measures multivariate analyses of variance (MANOVA) results suggested that being exposed to violence or abuse did not affect perceptions of climate. Both climate and violence exposure were correlated with some strains both cross-sectionally and longitudinally, but repeated measures MANOVAs failed to find evidence that exposure to violence or abuse would result in an increase in strain over time. It is concluded that the direction of effects is from climate to violence/abuse but not the reverse, and that climate should be a target for interventions designed to keep employees safe from both forms of mistreatment.     

Semiparametric models of longitudinal and time-to-event data with applications to HIV viral dynamics and CD4 counts

We propose a semiparametric approach based on proportional hazards and copula method to jointly model longitudinal outcomes and the time-to-event. The dependence between the longitudinal outcomes on the covariates is modeled by a copula-based times series, which allows non-Gaussian random effects and overcomes the limitation of the parametric assumptions in existing linear and nonlinear random effects models. A modified partial likelihood method using estimated covariates at failure times is employed to draw statistical inference. The proposed model and method are applied to analyze a set of progression to AIDS data in a study of the association between the human immunodeficiency virus viral dynamics and the time trend in the CD4/CD8 ratio with measurement errors. Simulations are also reported to evaluate the proposed model and method.     

Generalized Linear Mixed Models Based on Latent Markov Heterogeneity Structures

We describe a generalized linear mixed model in which all random effects may evolve over time. Random effects have a discrete support and follow a first‐order Markov chain. Constraints control the size of the parameter space and possibly yield blocks of time‐constant random effects. We illustrate with an application to the relationship between health education and depression in a panel of adolescents, where the random effects are highly dimensional and separately evolve over time.     

An exploratory study of multiple distinct gambling trajectories in emerging adults

This study uses data from a four-wave longitudinal survey of emerging adults (18–20 years of age in Wave 1) to examine whether there are multiple distinct trajectories of problem gambling risk severity and whether membership in these trajectory classes can be predicted by certain risk and protective factors. Four trajectory classes of gambling risk severity were identified – nonproblem-diminishing (73.9%), low-risk-stable (16.8%), marginal/nongambler-diminishing (7.1%), moderate-risk-increasing (2.2%) – with most youths' gambling involvement remaining stable or diminishing across the years and only the smallest most at-risk group showing a slight increase in severity across this transitional period. Three risk factors were significant predictors of class membership – being male, scoring higher on alcohol dependence, and escape-avoidance coping were all associated with increased probability of being in one of the more gambling involved trajectory classes, while lower alcohol dependence scores were associated with increased likelihood of being in the marginal/nongambling class.     

Large sample properties and confidence bands for component-wise varying-coefficient regression with longitudinal dependent variable

Longitudinal studies with repeatedly measured dependent variable (out-come) and time-invariant covariates are common in biomedical and epidemi-ological studies. A useful statistical tool to evaluate the effects of covariates on the outcome variable over time is the varying-coefficient regression, which considers a linear relationship between the covariates and the outcome at a specific time point but assumes the linear coefficients to be smooth curves over time. In order to provide adequate smoothing for each coefficient curve, Wu and Chiang ( 1999 ) proposed a class of component-wise kernel estimators and determined the large sample convergence rates and some of the constant terms of the mean squared errors of their estimators. In this paper we calcu¬late the explicit large sample mean squared errors, including the convergence rates and ail the constant terms, and the asymptotic distributions of the kernel estimators of Wu and Chiang ( 1999 ). These asymptotic distributions are used to construct point-wise confidence intervals and Bonferroni-type confidence bands for the coefficient curves. Through a Monte Carlo simulation, wre show that our confidence regions have adequate coverage probabilities. Applying our procedures to a NIH fetal growth study, we show that our procedures are useful to determine the effects of maternal height, cigarette smoking and al¬cohol consumption on the growth of fetal abdominal circumference over time during pregnancy.     

辽宁省非公有制林业发展研究

非公有制林业是现代林业发展的必然方向。辽宁省非公有制林业发展迅速，总量不断增加，规模不断扩大，领域不断拓宽，实力不断增强，已经成为林业建设的重要力量和决定因素。但在发展中受到规模不大、经营分散、资金筹集困难等内部因素和林木采伐限额、税费负担较重、林权证流转制度不健全、交易市场不完善等外部因素制约。因此，要引导农民建立专业合作组织，扩大生产经营规模；坚持政策的稳定性和连续性，适度放开采伐限度制度；完善林权流转机制，因地制宜制定林地流转方案；创新林业投融资本体制，开展林权抵押贷款业务；加大林业税费调整力度，为非公有林生产经营者创造合理赢利空间；完善林业社会化服务体系，构建森林资产评估平台。     

Living Arrangements During Childrearing Years and Later Health of African American Mothers

Using longitudinal data from the Woodlawn Project (N= 680), this study examined how patterns of living arrangements among a community cohort of African American mothers were associated with later physical and emotional health. We identified eight patterns of stability and transition in living arrangements during the childrearing years. Health outcomes include SF‐36 Physical Functioning, SF‐36 Bodily Pain, depressed mood, and anxious mood. Specific patterns of living arrangements were related to later health, controlling for age, earlier health, education, and poverty. Poverty explained many, but not all, of the relationships between living arrangements and health. Findings underscored the benefits of social support and social integration and highlighted the negative effects of marital dissolution on health.