Comparing relative importance of the same component in a series system in two environments

The relative performance of a component of a series system in two different environments is considered. The conditional probability of the failure of the system due to the failure of the specified component given that the system failed before time t is regarded as a measure of relative importance of the component to the system. A U-statistic test for checking the equality of the relative importance of the component to the system in two different environments against the alternative that the relative importance is smaller in one of the environments, is proposed. Some simulation results for estimating the power of the test are reported. The proposed test is applied to one real data set and it is seen that a different aspect of the data is brought out by this comparison than that by the comparisons of the absolute importance functions such as the subsurvival functions, considered in earlier studies.     

Risk Factors for Clinically Significant Intimate Partner Violence Among Active‐Duty Members

Hypothesized risk factors for men's and women's clinically significant intimate partner violence (CS‐IPV) from four ecological levels (i.e., individual, family, workplace, community) were tested in a representative sample of active‐duty U.S. Air Force members (N = 42,744). When considered together, we expected only individual and family factors to account for unique variance in CS‐IPV perpetration. Hypothesized factors from all four ecological levels were related to men's CS‐IPV perpetration bivariately, but, as expected, only individual and family factors accounted for unique variance across ecological levels. For women, only risk factors from the individual and family levels were significantly related to CS‐IPV perpetration even bivariately. Results imply somewhat different risk profiles across gender and identify ecological risk factors of men's CS‐IPV not previously studied.     

A Big Brother: New Findings on How Low-Income Fathers Define Responsible Fatherhood

I interviewed 57 low-income fathers about how they define responsible fatherhood. Unlike findings from previous research, their definition did not include financial provision or daily caregiving. Instead, their definition included six dimensions, some of which resemble a “Big Brother”: spending time in non-caregiving activities; avoiding harm by voluntarily distancing from the child when it is in the child’s best interest; acknowledging paternity in non-legal forums; spending money on gifts, joint activities, and special needs; monitoring the child’s home for trouble; and minimizing absences in the child’s life. Because these fathers do not emphasize traditional breadwinning or primary caregiving, their responsible fathering beliefs and behavior may be unappreciated by academics, practitioners, and policy makers.     

Innovations to Make Markets More Inclusive for the Poor

Market failures, government failures and some of the characteristics of both the poor and business actors as well as their environment can act as barriers preventing the poor from participating more actively in markets, both as consumers and as producers. Private actors ‐ including for‐profit and not‐for‐profit entities, often in partnership with the public sector ‐ have been able to mitigate some of these constraints through innovations that have helped to make markets more inclusive for the poor, enabling them not just to gain access, but also to participate in ways that enhance their economic empowerment and human development. This article identifies the strategies and innovations used and devises a possible typology for them.     

基于NURBS方法的转子表面造型技术

采用双三次NURBS方法对某型号转子进行几何造型,对造型过程中出现的曲面延伸、求交和裁剪等问题进行了研究.根据叶片的形状特征,以曲线的几何形式为基础,提出了一种简单实用的曲线曲面延伸方法,实现了切矢量连续的叶片型面的延伸.对于两相交面分别为自由曲面和解析曲面的求交问题,提出了一种简化的跟踪算法,实现了转子叶片型面和圆台面的准确求交和裁剪,从而实现转子精确的几何造型.     

完全检查下预防维修模型建立及案例分析

为了解决维修间隔期确定的难题,建立了维修间隔期和总停机时间之间关系的目标函数,以及时间延迟维修模型.根据故障记录数据和预防维修活动的检查数据,采用最大似然法估计有关缺陷发生率和时间延迟分布等参数.在所建立目标函数和估计参数的基础上,计算出最优的维修间隔期.     

Adolescent Immigrants in Search of Identity: Clingers, Eradicators, Vacillators and Integrators

This conceptual article explores mechanisms used by adolescent immigrants from the former Soviet Union to cope with issues of identity. Based on her experience in the Russian Adolescents Project of the Jewish Board of Services for Families and Children in Brighton Beach, Brooklyn New York, the writer identifies four patterns of coping with identity issues among immigrant adolescents and discusses individual and social factors that impact on the choice of a coping pattern.     

The Jackknife estimate of covariance of two Kaplan–Meier integrals with covariables

In this paper the Jackknife estimate of covariance of two Kaplan–Meier integrals with covariates is introduced. Its strong consistency is established under mild conditions. Several applications of the estimator are discussed.     

Expanded renal transplantation: a competing risk model approach

Multi-state models (MSMs) are useful to analyze survival data when, besides the event of main interest, one or more intermediate states of the individual are identified. These models take the several existing states and the possible transitions among them into account. At the same time, covariate effects on each transition intensity may be investigated separately and, therefore, MSMs are more flexible than the standard Cox proportional hazards model. In this work, we use MSMs to investigate the impact of the quality of a transplanted kidney for a group of patients at the Hospital Universitario Central de Asturias. Specifically, we use an illness-death model to study the evolution of patients with kidney disease who received a renal transplant after a dialysis period. The intermediate state is defined as the failure of the received organ, while the terminating state is the death of the patient. In order to increase the potential number of organs available for transplant, the standards of quality for the transplanted kidneys were relaxed (the new criteria are labeled expanded criteria), and these ‘expanded kidneys’ were transplanted in appropriate candidates (older patients, with higher prevalence of diabetes mellitus). Results suggest that the expanded kidneys have a minor effect on survival, while both the kidney mortality and the risk of death increase with the patient's age and the serum creatinine and serum hemoglobin levels.