基于遗传技术辅助设计的神经网络期货市场预测

本文在对期货市场的历史数据进行预分析的基础上,建立了神经网络期货市场预测模型．文中不仅对神经网络进行了改进研究,还利用遗传技术优化网络的结构和参数．运运实例对模型进行学习与测试的实验结果表明,利用遗传技术辅助设计的神经网络预测模型能较准确地预报期货价格的波动趋势.     

福建城镇居民恩格尔系数变化趋势及其响应

在复杂的经济系统中,恩格尔系数的变化由于受到诸多因素的影响往往呈现非线性变化趋势的特征。该文以恩格尔系数为研究对象,利用人工神经网络模型在非线性定量分析方面的优势,建立恩格尔系数变化趋势的BP神经网络预测模型,并对福建城镇居民恩格尔系数的变化趋势进行研究,提出未来几年恩格尔系数变化趋势几个方面的响应。     

Movement without mobility: Adolescent status hierarchies and the contextual limits of cumulative advantage

This paper develops a theory of interpersonal status hierarchies that builds on and challenges traditional models of cumulative advantage. Cumulative advantage models predict stability in interpersonal status hierarchies, where status is defined by asymmetries in social relationships. According to strict cumulative advantage, initial status differences are exaggerated over time, making upward or downward mobility unlikely. We argue that interpersonal status hierarchies are instead quite fluid, with individuals regularly moving up or down the hierarchy. Individual status gains do not, however, disrupt the status order as the upwardly mobile are often pulled back to their original positions. This drag of the past generates the same long run status outcomes as cumulative advantage models, but through very different means: sustained upward mobility is rare because the upwardly mobile fail to maintain their status gains, and not because initial gains are impossible. More generally, the effect of the past limits sustained mobility in most, but not all, status hierarchies, and we expect sustained mobility where ties are stable and the expectations for reciprocity are low. We test our model using longitudinal data on adolescents, finding strong support for the theory. We end the paper with a reflexive discussion about measurement error, hypothesis testing, and “messy” longitudinal network data.     

The structure of online social networks mirrors those in the offline world

We use data on frequencies of bi-directional posts to define edges (or relationships) in two Facebook datasets and a Twitter dataset and use these to create ego-centric social networks. We explore the internal structure of these networks to determine whether they have the same kind of layered structure as has been found in offline face-to-face networks (which have a distinctively scaled structure with successively inclusive layers at 5, 15, 50 and 150 alters). The two Facebook datasets are best described by a four-layer structure and the Twitter dataset by a five-layer structure. The absolute sizes of these layers and the mean frequencies of contact with alters within each layer match very closely the observed values from offline networks. In addition, all three datasets reveal the existence of an innermost network layer at ∼1.5 alters. Our analyses thus confirm the existence of the layered structure of ego-centric social networks with a very much larger sample (in total, >185,000 egos) than those previously used to describe them, as well as identifying the existence of an additional network layer whose existence was only hypothesised in offline social networks. In addition, our analyses indicate that online communities have very similar structural characteristics to offline face-to-face networks.     

Migrant Children,Social Capital and Access to Services Post‐Migration: Transitions,Negotiations and Complex Agencies

For migrant children, moving to a new country is marked by excitement, anxiety and practical challenges in managing this significant transition. This paper draws upon the concepts of social capital and social networks to examine migrant children's access to services post‐migration. Using data from a qualitative study with Eastern European families in Scotland, we identify a range of cumulative barriers that limit children's access to services and illustrate how their experiences are shaped by ethnicity, social class and place. The study shows that migrant children are often disadvantaged post‐migration and develop their own mechanisms to mitigate the impact of migration on their lives. We argue that migrant children's own social networks are relevant and they need to be analysed through a more individualised approach.     

自组织、创新网络和路径创造

基于自组织理论,本文认为复杂的自组织创新网络是对以前简单的、等级的组织结构和过程,面对复杂技术的创新无能为力的一种反映。技术创新是一个自组织进化的过程,网络和复杂性技术共同进化,复杂性技术导致技术创新的自组织进化,从而导致自组织创新网络的产生、发展和演化,自组织创新网络的不断演化,形成了路径创造的各种方法和工具。最终使得技术创新产生根本性创新或者技术创新范式的变化。     

集群内合作网络构建中的政府作用：欧洲经验

产业集群是区域竞争力的主要载体,而集群内企业合作网络建设是产业集群持续发展的关键要素,政府在其中扮演着重要的推动力量.文章梳理了欧洲各国政府在支持集群合作网络建设方面的主要政策措施,并以奥地利上奥州为例,详细考察了政府在集群内企业合作网络构建中的角色定位、政策重点和采取的具体工具,最后通过总结欧洲国家的经验,为中国地方政府更好地发展产业集群提供有益的借鉴.     

宗族网络与传统手工技艺保护——闽南永春漆篮技艺调查

传统手工技艺保护作为一项正式制度已得到了国家的推行,而宗族网络能够发挥非正式制度的有效功能,执行规范约束能力,降低正式制度的执行成本,提高管理效率,促进传统手工技艺的保护。通过对闽南永春漆篮技艺的调查,分析传统手工技艺保护与宗族网络的关系,揭示村庄精英如何利用宗族网络的力量动员相关人士参与传统手工技艺保护,体现正式制度与非正式制度的融合。     

‘The confidence to know I can survive’: resilience and recovery in post-quake Christchurch

This paper explores the relevance of terms such as resilience and recovery when analysing earthquake stories recorded for the Women's Voices/Ngā Reo o Ngā Wahine Project after the sequence of earthquakes and aftershocks in Christchurch, New Zealand's second-largest city, in 2010–2011. While the media focused on stories of victims, the heroic work of rescue teams, policy, army and firefighters, or the deliberations of national and local politicians, the National Council of Women of New Zealand wanted to ensure that women's everyday quake experiences were recorded for posterity. The outcome was an oral history project that documented the stories of women all over the city, both beneficiaries of earthquake support and those active in assisting others. Their narratives illustrate how resilience in the face of natural hazard events, such as this earthquake sequence, requires effort, ingenuity and imagination, but also the activation of multiple actor networks and relevant technologies. These ‘insider stories’ also highlight the ways in which expectations of ‘resilience’ can obscure vulnerability after natural hazard events and the complex and uneven processes associated with ‘recovery’. The relevance of critical reflections on discourses of resilience is explored through attention to the stories of specific women.     

Of employers,uncles and interpreters: the diverse trajectories of guest workers to the Belgian city of Ghent, 1960–1975

This article addresses a lesser-known part of post-war migration to Europe: the actual trajectories through which guest workers arrived in the countries of destination. Currently, these trajectories are explained through two models: that of large-scale employer recruitment and that of chain migration through personal networks. This article argues, however, that these two explanatory models oversimplify a complex historical reality. First, both models tend to be interpreted rather narrowly. Through an extensive discussion of the many different trajectories of guest workers to the Belgian city of Ghent, this article provides a more diffuse interpretation, focusing on the high degree of complexity within and overlap between them. Second, the existing models do not leave much space for a third category of agents: the so-called migration middlemen. This article places these middlemen in the spotlight, looking at their role as well as at their perception by contemporary actors. By providing a more encompassing picture of the actual migration trajectories of guest workers, of the many actors involved in them, and of the different migration regimes framing them, the article hopes to contribute to a better understanding of the ways in which people move not only in the past but also in the present.