Query-oriented text summarization based on hypergraph transversals

The rise in the amount of textual resources available on the Internet has created the need for tools of automatic document summarization. The main challenges of query-oriented extractive summarization are (1) to identify the topics of the documents and (2) to recover query-relevant sentences of the documents that together cover these topics. Existing graph- or hypergraph-based summarizers use graph-based ranking algorithms to produce individual scores of relevance for the sentences. Hence, these systems fail to measure the topics jointly covered by the sentences forming the summary, which tends to produce redundant summaries. To address the issue of selecting non-redundant sentences jointly covering the main query-relevant topics of a corpus, we propose a new method using the powerful theory of hypergraph transversals. First, we introduce a new topic model based on the semantic clustering of terms in order to discover the topics present in a corpus. Second, these topics are modeled as the hyperedges of a hypergraph in which the nodes are the sentences. A summary is then produced by generating a transversal of nodes in the hypergraph. Algorithms based on the theory of submodular functions are proposed to generate the transversals and to build the summaries. The proposed summarizer outperforms existing graph- or hypergraph-based summarizers by at least 6% of ROUGE-SU4 F-measure on DUC 2007 dataset. It is moreover cheaper than existing hypergraph-based summarizers in terms of computational time complexity.     

The Use of Social Media by Chinese Climate Journalists: A Case Study of COP21

ABSTRACT

The aim of this paper is to probe into the social media use by Chinese climate journalists through the examination of their professional practices on social media. Taking COP21 as a case, the study conducted a survey from Chinese COP21 journalists and analyzed WeChat and Weibo posts from Chinese journalists and tweets from their UK and US colleagues. The results show the prevalent use of WeChat among Chinese journalists and the personalization of the social media content accordingly. Compared to their Western counterparts, the use of social media for professional purposes by Chinese COP21 journalists was relatively limited. Nevertheless, several patterns of using social media were identified. Specifically, Chinese journalists tended to more frequently express personal opinions, discuss work experience and favor conventional news sources of authority than UK and US journalists. The results also suggest that climate change in Chinese media discourse will remain more a policy-related issue instead of an environmental or scientific issue, with Chinese government playing a central role.     

Attitudes of Secondary School STEM Teachers towards Supervising Research and Design Activities

Research and design activities are important focus points in international policies for secondary Science, Technology, Engineering and Mathematics (STEM) education. It is up to school teachers to implement and supervise these activities in the STEM classroom. However, not much is known about the attitudes teachers hold towards supervising research projects or design projects. In this study, a questionnaire to measure teacher attitudes towards supervising research activities and design activities in secondary school was completed by 130 Dutch teachers who taught the relatively new Dutch STEM subjects O&O (research and design) and NLT (nature, life, and technology). These integrated STEM subjects are project and context based and are taught in a limited number of schools. Important differences between these integrated STEM subjects are their student and teacher populations: NLT is taught in grades 10–12 by teachers with a qualification in a science subject, while O&O is taught in grades 7–12 and can be given by any teacher in secondary school. The results showed that on average, both O&O and NLT teachers had high self-efficacy scores on supervising research and design projects even when they had received no special education in doing so. Furthermore, the teachers in general viewed supervising research projects as a more relevant activity than supervising design. Since research and design activities are becoming more important in (inter)national curriculum standards, STEM teacher education and subsequent professional development should not only familiarize teachers with supervising research projects, but with design projects as well.

     

First Possession,History, and Young Children's Ownership Judgments

It is impossible to perceive who owns an object; this must be inferred. One way that children make such inferences is through a first possession bias—when two agents each use an object, children judge the object belongs to the one who used it first. Two experiments show that this bias does not result from children directly inferring ownership from first possession; the experiments instead support an alternative account according to which the first possession bias reflects children's historical reasoning. In Experiment 1, eighty‐five 3‐ to 5‐year‐olds only based inferences on first possession when it was informative about the past. In Experiment 2, thirty‐two 5‐year‐olds based ownership judgments on testimony about past contact, while disregarding testimony about future contact.