Bayesian analysis of bilinear time series models : a gibbs sampling approach

Nonlinear time series analysis plays an important role in recent econometric literature, especially the bilinear model. In this paper, we cast the bilinear time series model in a Bayesian framework and make inference by using the Gibbs sampler, a Monte Carlo method. The methodology proposed is illustrated by using generated examples, two real data sets, as well as a simulation study. The results show that the Gibbs sampler provides a very encouraging option in analyzing bilinear time series.     

Positivity conditions for stochastic state space modelling of time series

This short paper clarifies some aspects of the balancing method for state space modelling of observed time series. This method may fail to satisfy the so-called positive real condition for stochastic processes. We illustrate this by theoretical spectral analysis and also by simulating univariate ARMA (1,1) models.     

A New Approach to the Group Ranking Problem: Finding Consensus Ordered Segments from Users’ Preference Data

The group ranking problem involves constructing coherent aggregated results from users’ preference data. The goal of most group ranking problems is to generate an ordered list of all items that represents the user consensus. There are, however, two weaknesses to this approach. First, a complete list of ranked items is always output even when there is no consensus or only a slight consensus. Second, due to similarity of performance, in many practical situations, it is very difficult to differentiate whether one item is really better than another within a set. These weaknesses have motivated us to apply the clustering concept to the group ranking problem, to output an ordered list of segments containing a set of similarly preferred items, called consensus ordered segments. The advantages of our approach are that (i) the list of segments is based on the users’ consensuses, (ii) the items with similar preferences are grouped together in the same segment, and (iii) the relationships between items can be easily seen. An algorithm is developed to construct the consensus of the ordered segments from the users’ total ranking data. Finally, the experimental results indicate that the proposed method is computationally efficient, and can effectively identify consensus ordered segments.     

Aids and population growth in sub-Saharan Africa: Assessing the sensitivity of projections

Despite different models to project the course of the AIDS pandemic and a scarcity of data to provide standard input parameters for those models, a limited consensus emerges from distinct sets of population projections. In sub-Saharan Africa, population growth rates are projected to remain positive in spite of the pandemic over the next few decades. To investigate this conclusion, alternative projections of an HIV/AIDS epidemic and its related mortality are first produced from different sets of input parameters and assumptions. Their incorporation into the population projections of a fast-growing country illustrates the robustness of projected population growth rates under very different scenarios of the future epidemic but with the common assumption that it will not affect the mortality of the uninfected population, fertility nor migration. This paper then shows that the projected growth rates are much less robust when interactions between the epidemic and the demographic regime are allowed and identifies several potential mechanisms for such interactions. In particular, it suggests that improving our confidence in the medium-term projections of the demographic impact of AIDS in the region requires less a refinement of the projections of the epidemic than a better understanding of its impact on the timing of the postulated fertility decline.     

《周易》象思维在现代哲学范式中的解读及意义

对《周易》卦象哲学意义的解读通常是以近代哲学思维范式来进行的,即把卦象理解为“古代朴素辩证法”。如以现代哲学思维范式来解读,卦象是“存在(是)”的思维,是表现“势”的。它以“势”来规定“存在者”,又以“存在者”来参与“势”,现代哲学范式在批判方面是成功的,在建设方面是不成功的。因其并未能找到再现“生存状态”的语言。卦象以非语言的“领会”的方式“去蔽”,再现了处于时间中的“生存状态”,满足了现代哲学范式对统一性与多样性的要求,也为道德重建提供了生存论的根据。     

How do health professionals support pregnant and young mothers in the community? A selective review of the research literature

BackgroundThe cultural phenomenon of “teenage pregnancy and motherhood” has been socially constructed and (mis)represented in social and health care discourses for several decades. Despite a growing body of qualitative research that presents an alternative and positive view of young motherhood, there remains a significant gap between pregnant and young women's experience of young motherhood and current global health and social policy that directs service delivery and practice.AimThis paper aims to heighten awareness of how a negative social construction of young motherhood influences global health and social policy that directs current community health models of practice and care for young mothers in the community.DiscussionThere is clear evidence on the vital role social support plays in young women's experience of pregnancy and motherhood, particularly in forming a positive motherhood identity. This discussion paper calls us to start open and honest dialogue on how we may begin to re-vision the ‘deficit view’ of young motherhood in order to address this contradiction between research evidence, policy discourse and current practice and service provision. Qualitative research that privileges young women's voices by considering the multidimensional experiences of young motherhood is an important step towards moving away from universally prescribed interventions to a non-standard approach that fosters relational and responsive relationships with young mothers that includes addressing the immediate needs of young mothers at the particular time.     

Generalization of multi-item,multi-retailer distribution system

The procedure developed by Muckstadt and Roundy is generalized. In a multi-echelon inventory system with a single warehouse and multi-retailers, some di erent items with constant demand rates are distributed. Considering set-up and holding costs as well as the cost of joint shipment of items from the warehouse to any retailer, the objective is to minimize the total costs of the system. In the proposed algorithm the assumption of nested policies is relaxed. The procedure introduced works for both nested and non-nested policies.     

Understanding the self-organization of occupational sex segregation with mobility networks

Decades after the beginning of the gender revolution, most women and men still work in sex-typed occupations. This is a primary driver of the gender wage gap. Most research describing the patterns of occupational sex segregation focuses on supposedly innate job characteristics that match gender stereotypical abilities and preferences, such as the use of mathematical skills or social skills, on income and status differences between occupations, and on organizational job characteristics, for example, the need to work long hours. However, beyond such occupational attributes, sex segregation is hypothesized to exhibit emergent patterns that are linked to the interdependent job mobility of women and men, in particular, men selectively leaving feminizing occupations. Developing new tools inspired by statistical network research, and using representative, longitudinal data that contain detailed occupational mobility from the UK between 2000 and 2008, this replacement mechanism is analyzed. It is shown that 19–28% of observed sex segregation is linked to this emergent phenomenon in a statistical model that disentangles the various predictors of the allocation of women and men to different occupations. This makes it the most important predictor of segregation in contrast to concurrently modelled explanations based on occupational characteristics.Data and materials availabilityThe BHPS data and the LFS data are available from the UK Data Service (https://www.ukdataservice.ac.uk/). The O*NET data is available from the O*NET homepage (https://www.onetcenter.org/). Software implemented in the environment R and code for data analysis are available upon request from the authors.     

近十年来二语学习动因研究：批评和重建

20世纪90年代二语学习动因研究表现出两大特征对此领域代表人物Gardner理论的批评和新模式重建.本文从这两方面系统地评述近十年来二语学习动因研究的发展,讨论此领域亟待解决的问题.     

案例教学模式与教师专业发展初探

以案例教学促进教师专业发展 ,是一种行之有效的方法。在教师积累了一定经验的基础上 ,培训者可通过分析案例 ,促使教师反思提高。案例分析的过程可分四步 :自主学习、初步分析———小组讨论、完善分析———抽签定题、重点分析———全班交流、透彻分析。