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1.
Five hundred million tweets are posted daily, making Twitter a major social media platform from which topical information on events can be extracted. These events are represented by three main dimensions: time, location and entity-related information. The focus of this paper is location, which is an essential dimension for geo-spatial applications, either when helping rescue operations during a disaster or when used for contextual recommendations. While the first type of application needs high recall, the second is more precision-oriented. This paper studies the recall/precision trade-off, combining different methods to extract locations. In the context of short posts, applying tools that have been developed for natural language is not sufficient given the nature of tweets which are generally too short to be linguistically correct. Also bearing in mind the high number of posts that need to be handled, we hypothesize that predicting whether a post contains a location or not could make the location extractors more focused and thus more effective. We introduce a model to predict whether a tweet contains a location or not and show that location prediction is a useful pre-processing step for location extraction. We define a number of new tweet features and we conduct an intensive evaluation. Our findings are that (1) combining existing location extraction tools is effective for precision-oriented or recall-oriented results, (2) enriching tweet representation is effective for predicting whether a tweet contains a location or not, (3) words appearing in a geography gazetteer and the occurrence of a preposition just before a proper noun are the two most important features for predicting the occurrence of a location in tweets, and (4) the accuracy of location extraction improves when it is possible to predict that there is a location in a tweet. 相似文献
2.
Anthony Bigot Claude Chrisment Taoufiq Dkaki Gilles Hubert Josiane Mothe 《Information Retrieval》2011,14(6):617-648
To evaluate Information Retrieval Systems on their effectiveness, evaluation programs such as TREC offer a rigorous methodology
as well as benchmark collections. Whatever the evaluation collection used, effectiveness is generally considered globally,
averaging the results over a set of information needs. As a result, the variability of system performance is hidden as the
similarities and differences from one system to another are averaged. Moreover, the topics on which a given system succeeds
or fails are left unknown. In this paper we propose an approach based on data analysis methods (correspondence analysis and
clustering) to discover correlations between systems and to find trends in topic/system correlations. We show that it is possible
to cluster topics and systems according to system performance on these topics, some system clusters being better on some topics.
Finally, we propose a new method to consider complementary systems as based on their performances which can be applied for
example in the case of repeated queries. We consider the system profile based on the similarity of the set of TREC topics
on which systems achieve similar levels of performance. We show that this method is effective when using the TREC ad hoc collection. 相似文献
3.
Despite the vast literature on knowledge management, little research has addressed the specificities of knowledge integration at the cluster level. Moreover, the literature on clusters has not focused on the role that governance may play in knowledge management. Anchored in a knowledge-based perspective, this paper aims at bridging the two fields, filling the gap by analysing the role of cluster governance in knowledge management. An empirical study of two small French firm clusters was carried out based on 29 interviews. The data analysis consisted essentially in content analysis. The clusters studied were characterized by distinct knowledge management processes. In both cases, governance was necessary in order to support knowledge integration by member firms. Our results suggest that establishing an initial common knowledge base seems to be a prerequisite in order for the external knowledge identification and acquisition processes to take place. The activist role played by governance also seems more efficient than that of a broker. We discuss these results and their implications for policy-makers and cluster members. 相似文献
4.
Pascale Marguerite Josiane Engel de Abreu Susan Elizabeth Gathercole Romain Martin 《Learning and individual differences》2011,21(5):569-574
This study investigates the relationship between working memory and language in young children growing up in a multilingual environment. The aim is to explore whether mechanisms of short-term storage and cognitive control hold similar relations to emerging language skills and to investigate if potential links are mediated by related cognitive abilities. A sample of 119 Luxembourgish 6-year-olds completed several assessments of working memory (complex and simple span), native and foreign vocabulary, syntax, reading, rhyme awareness, and fluid intelligence. Results showed that short-term storage and cognitive control manifested differential links with developing language abilities: Whereas verbal short-term storage was specifically linked to vocabulary; cognitive control manifested unique and robust links with syntax and early reading development. The study suggests that in young children the working memory system is composed of separate but interacting components corresponding to short-term storage and cognitive control that can be distinguished by the roles they play in supporting language acquisition. 相似文献
5.
To identify how a governance structure leads to ambidexterity at the cluster level, in terms of knowledge management, this study draws on the knowledge -based view of clusters and on ambidexterity literature, thereby exploring an ‘intermediated’ cluster model of ambidexterity. Our aim is to explore the governance structure’s role and priorities in terms of knowledge management, as well as the underlying operational actions and programmes implemented to achieve cluster ambidexterity. Qualitative research, based on interviews with members of two French clusters, reveals that their governance structure is a crucial intermediary organisation that supports cluster ambidexterity. The results emphasise the role of governance structures for two types of ambidexterity in small and medium-sized enterprise (SME) clusters: First, SMEs may specialise in exploitative or exploratory knowledge, and the governance structure provides the missing knowledge (intermediated specialised model). Second, cluster governance may help each firm become ambidextrous (intermediated dual model). This study outlines the specificities of the two models and their contingency factors, which offer interesting implications, especially for policymakers devoted to innovation and clusters. 相似文献
6.
Modeling context through domain ontologies 总被引：1，自引：0，他引：1
Nathalie Hernandez Josiane Mothe Claude Chrisment Daniel Egret 《Information Retrieval》2007,10(2):143-172
Traditional information retrieval systems aim at satisfying most users for most of their searches, leaving aside the context
in which the search takes place. We propose to model two main aspects of context: The themes of the user's information need
and the specific data the user is looking for to achieve the task that has motivated his search. Both aspects are modeled
by means of ontologies. Documents are semantically indexed according to the context representation and the user accesses information
by browsing the ontologies. The model has been applied to a case study that has shown the added value of such a semantic representation
of context.
相似文献
| Daniel EgretEmail: |
7.
Adrian-Gabriel Chifu Florentina Hristea Josiane Mothe Marius Popescu 《Information processing & management》2015
Word sense ambiguity has been identified as a cause of poor precision in information retrieval (IR) systems. Word sense disambiguation and discrimination methods have been defined to help systems choose which documents should be retrieved in relation to an ambiguous query. However, the only approaches that show a genuine benefit for word sense discrimination or disambiguation in IR are generally supervised ones. In this paper we propose a new unsupervised method that uses word sense discrimination in IR. The method we develop is based on spectral clustering and reorders an initially retrieved document list by boosting documents that are semantically similar to the target query. For several TREC ad hoc collections we show that our method is useful in the case of queries which contain ambiguous terms. We are interested in improving the level of precision after 5, 10 and 30 retrieved documents (P@5, P@10, P@30) respectively. We show that precision can be improved by 8% above current state-of-the-art baselines. We also focus on poor performing queries. 相似文献
8.
Beth Warren Cynthia Ballenger Mark Ogonowski Ann S. Rosebery Josiane Hudicourt‐Barnes 《科学教学研究杂志》2001,38(5):529-552
There are many ways to understand the gap in science learning and achievement separating low‐income, ethnic minority and linguistic minority children from more economically privileged students. In this article we offer our perspective. First, we discuss in broad strokes how the relationship between everyday and scientific knowledge and ways of knowing has been conceptualized in the field of science education research. We consider two dominant perspectives on this question, one which views the relationship as fundamentally discontinuous and the other which views it as fundamentally continuous. We locate our own work within the latter tradition and propose a framework for understanding the everyday sense‐making practices of students from diverse communities as an intellectual resource in science learning and teaching. Two case studies follow in which we elaborate this point of view through analysis of Haitian American and Latino students' talk and activity as they work to understand metamorphosis and experimentation, respectively. We conclude with a discussion of the implications of this new conceptualization for research on science learning and teaching. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 529–552, 2001 相似文献
9.
The importance of knowledge ingovernance presents increasing pressures on thescience-society contract. A re-thinking of thenature of `knowledge policy' is required. Byexamining the changing context and processes ofthe production of knowledge, this articleexamines whether and how policy organizationscan learn to adapt to complex knowledgeenvironments. 相似文献
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