Families and family study in international perspective

Many changes are occurring in the world's families. Some observers feel that the changes are destructive, whereas others see them as leading to new opportunities and understanding. Issues in international family studies include regional limitations and the various aspects of doing research cross‐culturally. Knowledge regarding certain categories of families, inheritance, and the social psychology of families is incomplete. There are, however, some universals and universal or worldwide changes, including movement toward individual partner choice, more divorces, lower fertility, and greater opportunities for women.     

A Mathematical Model for Pathogen Cross‐Contamination Dynamics during the Postharvest Processing of Leafy Greens

We developed a probabilistic mathematical model for the postharvest processing of leafy greens focusing on Escherichia coli O157:H7 contamination of fresh‐cut romaine lettuce as the case study. Our model can (i) support the investigation of cross‐contamination scenarios, and (ii) evaluate and compare different risk mitigation options. We used an agent‐based modeling framework to predict the pathogen prevalence and levels in bags of fresh‐cut lettuce and quantify spread of E. coli O157:H7 from contaminated lettuce to surface areas of processing equipment. Using an unbalanced factorial design, we were able to propagate combinations of random values assigned to model inputs through different processing steps and ranked statistically significant inputs with respect to their impacts on selected model outputs. Results indicated that whether contamination originated on incoming lettuce heads or on the surface areas of processing equipment, pathogen prevalence among bags of fresh‐cut lettuce and batches was most significantly impacted by the level of free chlorine in the flume tank and frequency of replacing the wash water inside the tank. Pathogen levels in bags of fresh‐cut lettuce were most significantly influenced by the initial levels of contamination on incoming lettuce heads or surface areas of processing equipment. The influence of surface contamination on pathogen prevalence or levels in fresh‐cut bags depended on the location of that surface relative to the flume tank. This study demonstrates that developing a flexible yet mathematically rigorous modeling tool, a “virtual laboratory,” can provide valuable insights into the effectiveness of individual and combined risk mitigation options.     

相互投资与人力资本投资对研发外包决策影响研究

本文运用产权理论模型,通过分析最优和次优两种状态下企业和研发机构的均衡投资水平,重点讨论企业和研发单位自我投资和相互投资对研发外包决策的影响,并通过进一步揭示物质资产与人力资产在研发外包中的作用,提出根据专用性投资的特点调整研发外包策略,继而实现最优的研发效果。研究结果表明:相互投资弹性更高的一方更应该拥有外包的所有权;企业应根据双方相互投资的投资弹性高低调整研发外包策略;外包项目中人力资本投资比物质资本投资更重要。研究结果对企业有效利用研发外包进行创新提供了有力的理论指导。     

Cross‐Training with Imperfect Training Schemes

Cross‐training workers is one of the most efficient ways of achieving flexibility in manufacturing and service systems for increasing responsiveness to demand variability. However, it is generally the case that cross‐trained employees are not as productive on a specific task as employees who were originally trained for that task. Also, the productivity of the cross‐trained workers depends on when they are cross‐trained. In this work, we consider a two‐stage model to analyze the effects of variations in productivity levels on cross‐training policies. We define a new metric called achievable capacity and show that it plays a key role in determining the structure of the problem. If cross‐training can be done in a consistent manner, the achievable capacity is not affected when the training is done, which implies that the cross‐training decisions are independent of the opportunity cost of lost demand and are based on a trade‐off between cross‐training costs at different times. When the productivities of workers trained at different times differ, there is a three‐way trade‐off between cross‐training costs at different times and the opportunity cost of lost demand due to lost achievable capacity. We analyze the effects of variability and show that if the productivity levels of workers trained at different times are consistent, the decision maker is inclined to defer the cross‐training decisions as the variability of demand or productivity levels increases. However, when the productivities of workers trained at different times differ, an increase in the variability may make investing more in cross‐training earlier more preferable.     

Is Marriage More Than Cohabitation? Well‐Being Differences in 30 European Countries

The study aims to assess, first, whether there is a gap in well‐being between unmarried cohabitants and the married, second, if selection factors can explain this so‐called cohabitation gap, and third, if the size of the cohabitation gap differs across countries and how this can be explained. We use pooled data from young adults (18–44) in 3 rounds of the European Social Survey (N ? 31, 500). Multilevel regression analyses show that there is a moderate cohabitation gap that can be partly explained with the selection factors material resources and religiosity. Country differences were clear and could partly be explained with the level of institutionalization: In countries where cohabitation is more accepted and more prevalent, the cohabitation gap is smaller.     

基督教美术中的十字架图式符号

随着基督教的诞生和发展,被称为"图画的圣经"的基督教美术也应运而生.基督教美术在创作范围内建立的特殊样式,主要是十字架这一图式符号的运用.画家们对十字架这一母题在基督教美术中的意义进行了拓展,对十字架的阐释经历了"原初性"、"神怪性"、"当代性"三层演进.     

Smoothing parameter selection methods for nonparametric regression with spatially correlated errors

When spatial data are correlated, currently available data‐driven smoothing parameter selection methods for nonparametric regression will often fail to provide useful results. The authors propose a method that adjusts the generalized cross‐validation criterion for the effect of spatial correlation in the case of bivariate local polynomial regression. Their approach uses a pilot fit to the data and the estimation of a parametric covariance model. The method is easy to implement and leads to improved smoothing parameter selection, even when the covariance model is misspecified. The methodology is illustrated using water chemistry data collected in a survey of lakes in the Northeastern United States.     

Evaluation of Atmospheric Transport Models for Use in Phase II of the Historical Public Exposures Studies at the Rocky Flats Plant

Five atmospheric transport models were evaluated for use in Phase II of the Historical Public Exposures Studies at the Rocky Flats Plant. Models included a simple straight-line Gaussian plume model (ISCST2), several integrated puff models (RATCHET, TRIAD, and INPUFF2), and a complex terrain model (TRAC). Evaluations were based on how well model predictions compared with sulfur hexafluoride tracer measurements taken in the vicinity of Rocky Flats in February 1991. Twelve separate tracer experiments were conducted, each lasting 9 hr and measured at 140 samplers in arcs 8 and 16 km from the release point at Rocky Flats. Four modeling objectives were defined based on the endpoints of the overall study: (1) the unpaired maximum hourly average concentration, (2) paired time-averaged concentration, (3) unpaired time-averaged concentration, and (4) arc-integrated concentration. Performance measures were used to evaluate models and focused on the geometric mean and standard deviation of the predicted-to-observed ratio and the correlation coefficient between predicted and observed concentrations. No one model consistently outperformed the others in all modeling objectives and performance measures. About 75% of the maximum hourly concentration predictions were within a factor of 5 of the observations. About 64% of the paired and 80% of the unpaired time-averaged model predictions were within a factor of 5 of the observations. The overall performance of the RATCHET model was somewhat better than the other models. All models appeared to experience difficulty defining plume trajectories, which was attributed to the influence of multilayered flow initiated by terrain complexities and the diurnal flow patterns characteristic of the Colorado Front Range.     

Measuring particularized trust: A name generator approach

In the social sciences, trust scholars largely divide their interests between two streams of research: one on generalized trust and one on particularized trust. While recent developments in the measurement of generalized trust have pushed the literature forward, similar improvements to the measurement of particularized trust have lagged behind. In this article, I advance trust research by (1) developing an egocentric particularized trust (EPT) instrument based on a multiple name generator approach, and (2) assessing EPT’s empirical performance across numerous psychometric tests. Results from a general population quota sample (N = 2041) indicate that EPT consists of two separate latent constructs, one for personally known others (EPT-K) and one for family members (EPT-F). Using traditional measures of particularized trust as benchmarks, I find that EPT-K and EPT-F provide the most valid and reliable measures of particularized trust. I conclude by discussing implications and directions for future research.     

学理境界与价值体认的双重突破——评刘起林《胜景与歧途——跨世纪文学的多维审视》

《胜景与歧途——跨世纪文学的多维审视》突破学术界既有框架和思路,从文学现实本身的特征与规律出发审视二十世纪最后十年到新世纪前十年的文学,用跨世纪文学的概念来命名这一具有内在统一性和生长性的文学历史进程。从民族精神文化多元而健全地发展的高度,选择和探索文学创作的主流,辨析其演变特征、文化逻辑、价值得失及应予提倡的发展方向。采用宏观态势考察与典型文本细读相结合的论述方式,持论有着强烈的问题意识和自觉的价值持衡立场,实现了创作与批评、文学批评与文学史的良性循环,显示出学理境界与价值体认的双重突破。