Bayesian analysis of single-molecule experimental data

Summary.  Recent advances in experimental technologies allow scientists to follow biochemical processes on a single-molecule basis, which provides much richer information about chemical dynamics than traditional ensemble-averaged experiments but also raises many new statistical challenges. The paper provides the first likelihood-based statistical analysis of the single-molecule fluorescence lifetime experiment designed to probe the conformational dynamics of a single deoxyribonucleic acid (DNA) hairpin molecule. The conformational change is initially treated as a continuous time two-state Markov chain, which is not observable and must be inferred from changes in photon emissions. This model is further complicated by unobserved molecular Brownian diffusions. Beyond the simple two-state model, a competing model that models the energy barrier between the two states of the DNA hairpin as an Ornstein–Uhlenbeck process has been suggested in the literature. We first derive the likelihood function of the simple two-state model and then generalize the method to handle complications such as unobserved molecular diffusions and the fluctuating energy barrier. The data augmentation technique and Markov chain Monte Carlo methods are developed to sample from the posterior distribution desired. The Bayes factor calculation and posterior estimates of relevant parameters indicate that the fluctuating barrier model fits the data better than the simple two-state model.     

A longitudinal study of perinatal depression among Chinese high-risk pregnant women

Background

Information is needed on the prevalence of depression in Chinese women with medically defined complications across the perinatal period, as well as key risk factors to develop appropriate perinatal mental health services and ensure the services target those most in need.

Crisis communication within a community: Bonding,coping, and making sense together

Crisis communication has been researched extensively from managerial and functionalist approaches, and little empirical research exists exploring the role of a community in helping community members cope with crises. Situated in this major gap, the current investigation adopts a community-centered approach that combines insights from chaos theory, uncertainty reduction theory, and sensemaking theory. This study used a mixed method design to examine the role of a campus community in dealing with a variety of campus crises. The qualitative study gave an in-depth understanding of how a crisis is perceived and the underlying process of how a community helps to make sense of a crisis. The quantitative study tested and further illustrated this process through path analysis. The major contributions of this study to the current crisis communication literature are twofold: (1) a crisis-induced community building model that demonstrates a community’s role in helping community members self-organize, collectively make sense of a crisis, and reproduce community experiences; and (2) instruments to measure a crisis and community functionalities. Theoretical implications of this study on chaos theory, uncertainty reduction theory, and sensemaking theory are discussed.     

The use of concept mapping in measurement development and evaluation: Application and future directions

The past decade has seen an increase of measurement development research in social and health sciences that featured the use of concept mapping as a core technique. The purpose, application, and utility of concept mapping have varied across this emerging literature. Despite the variety of uses and range of outputs, little has been done to critically review how researchers have approached the application of concept mapping in the measurement development and evaluation process. This article focuses on a review of the current state of practice regarding the use of concept mapping as methodological tool in this process. We systematically reviewed 23 scale or measure development and evaluation studies, and detail the application of concept mapping in the context of traditional measurement development and psychometric testing processes. Although several limitations surfaced, we found several strengths in the contemporary application of the method. We determined concept mapping provides (a) a solid method for establishing content validity, (b) facilitates researcher decision-making, (c) insight into target population perspectives that are integrated a priori, and (d) a foundation for analytical and interpretative choices. Based on these results, we outline how concept mapping can be situated in the measurement development and evaluation processes for new instrumentation.     

Development and Validation of TQM Implementation Constructs

The contemporary quality management (QM) literature prescribes various quality improvement strategies. However, it lacks scientifically developed and tested constructs that represent an integrative QM philosophy. Moreover, an impact of the prescribed QM strategies on a firm's product quality has not been analyzed. Through a detailed analysis of the literature, this research identifies 12 constructs of integrated QM strategies. Using a survey of 371 manufacturing firms, the constructs are then empirically tested and validated. LISREL 7 is used for this purpose. Finally, a framework to examine the effects of integrated QM strategies on a firm's product quality is suggested. Comparisons between this and two other comprehensive scales of TQM are made.     

政府研发投入规模的国际比较

文章以部分发达国家和新兴工业化国家为代表,对政府研发投入规模进行了国际比较。政府研发投入是带动整个国家研发投入,增强科技实力与经济增长的重要手段。国际经验表明,政府研发投入的规模决定了一国的科研投入水平,新兴工业化国家在科技追赶阶段,更需要政府投入的研发经费的超速增长。而我国目前政府研发投入的强度很低,与我国的经济实力乃至我国目前的经济社会发展战略很不相称。要实现产业结构的转型,提高政府研发投入强度已是迫在眉睫的任务。     

Product Positioning and Pricing Under Production Cost Considerations*

A framework in a competitive environment is proposed that incorporates production cost and economies of scale in the problem of positioning a product for a market segment. The model facilitates the existence of a Nash equilibrium in prices and product positions. As such, firms can simultaneously choose prices and product positions for the segment. This result improves the traditional theory on equilibria points in prices and product positions where firms choose their product positions first and then set their prices. A sensitivity analysis demonstrates the effects of changes in the unit savings derived from economies of scale or the cost of furnishing a product with its attributes by one firm on the product positions, prices, and profits of all competing firms. More important, the paper examines the effect on prices and profits of competing firms when one of the firms repositions its product closer to the segment's ideal point. It is shown that under certain conditions, the profit of a firm may actually decrease as it redesigns its product closer to the segment's ideal point. These conditions assist management to identify the product design beyond which enhancements of the product would lead to lower profits because of increasing production costs. It is also shown that the price of this firm increases. Past research supports the idea that positioning a brand closer to the ideal point, given fixed product positions of competing firms, would lead to greater buyer preferences and eventually higher profits. The price and profits of the competing firm may increase or decrease. Conditions are derived under which a movement towards the segment's ideal point by one firm would lead to higher profits by the competing firm.     

Psychometric Evaluation of the Tagalog and German Subjective Happiness Scales and a Cross-Cultural Comparison

The Subjective Happiness Scale (SHS) has recently been developed as a more complete measure for the assessment of molar subjective happiness. In the present study, we report on the translation and validation of German and Tagalog versions of the SHS and conduct an initial cross-cultural examination of subjective happiness. In Study 1, 960 participants in Austria completed a German version of the SHS, which showed a unidimensional structure, good internal consistency, and good convergent validity with other measures of subjective well-being. In Study 2, 182 participants in the Philippines completed a Tagalog version of the scale, which likewise had a unidimensional structure, high internal consistency, and good convergent validity. Finally, the results of Study 3 indicate that there were significant cross-cultural differences in subjective happiness. Specifically, participants in individualist Austria and Britain had higher SHS scores than their counterparts in collectivist Malaysia and the Philippines. Limitations of these studies are discussed.     

新疆哈萨克族人口规模变迁及分布

研究民族产生发展过程中的人口规模变迁及分布情况,将为了解民族历史演变提供新的背景。文章阐述了哈萨克族人口规模变迁和分布的基本内容与历史过程。     

农地经营权配置对农户收入影响的实证分析

农地流转是促进农地集中和规模化经营的重要手段,而明确农地经营权配置的集中程度对农户收入的影响,对于完善农地流转政策具有重要意义.运用2006年中国社会综合调查数据,利用基尼系数测算了农地经营权配置的集中程度,实证分析了农地经营权的集中程度对农户收入的影响,OLS回归分析发现,农地经营权的集中有利于农户收入水平的提高;分位数回归结果显示,农地经营权的集中更加有利于高收入农户,明显地提高了高收入农户的收入水平,而不利于低收入农户.因此,应当保证农地自由流转,促进农地经营权集中,提高大部分农户的收入水平;同时,对于不具有比较优势的低收入农户,应当制定相应的扶持政策和社会保障措施,保障其生活水平.