Hybrid clustering for validation and improvement of subject-classification schemes

A hybrid text/citation-based method is used to cluster journals covered by the Web of Science database in the period 2002–2006. The objective is to use this clustering to validate and, if possible, to improve existing journal-based subject-classification schemes. Cross-citation links are determined on an item-by-paper procedure for individual papers assigned to the corresponding journal. Text mining for the textual component is based on the same principle; textual characteristics of individual papers are attributed to the journals in which they have been published. In a first step, the 22-field subject-classification scheme of the Essential Science Indicators (ESI) is evaluated and visualised. In a second step, the hybrid clustering method is applied to classify the about 8300 journals meeting the selection criteria concerning continuity, size and impact. The hybrid method proves superior to its two components when applied separately. The choice of 22 clusters also allows a direct field-to-cluster comparison, and we substantiate that the science areas resulting from cluster analysis form a more coherent structure than the “intellectual” reference scheme, the ESI subject scheme. Moreover, the textual component of the hybrid method allows labelling the clusters using cognitive characteristics, while the citation component allows visualising the cross-citation graph and determining representative journals suggested by the PageRank algorithm. Finally, the analysis of journal ‘migration’ allows the improvement of existing classification schemes on the basis of the concordance between fields and clusters.     

Activity profile of top-class association football referees in relation to performance in selected physical tests

The aims of the present study were (1) to analyse the physical demands of top-class referees and (2) to compare their official FIFA fitness test results with physical performance during a match. The work rate profiles of 11 international referees were assessed during 12 competitive matches at the 2003 FIFA Under-17 World Cup and then analysed using a bi-dimensional photogrammetric video analysis system based on direct lineal transformation (DLT) algorithms. In the first 15 min of matches, the referees were more active, performing more high-intensity exercise (P < 0.01) than in the first 15 min of the second half. During the second half of matches, the referees covered a shorter distance (P < 0.01), spent more time standing still (P < 0.05), and covered less ground cruising (P < 0.05), sprinting (P < 0.05), and moving backwards (P < 0.001) than in the first half. Also in the second 45 min, the distance of referees from infringements increased (P < 0.05) in the left attacking zone of the filed. There was also a decrease (P < 0.05) in performance in the period following the most high-intensity activity, compared with the mean for the 90 min. Time spent performing high-intensity activities during a match was not related to performance in the 12-min run (r(2) = 0.30; P < 0.05), the 200-m sprint (r(2) = 0.05; P < 0.05), or the 50-m sprint (r(2) = 0.001; P < 0.05). The results of this study show that: (1) top-class referees experienced fatigue at different stages of the match, and (2) the typical field tests used by FIFA (two 50-m and 200-m sprints, followed by a 12-min run) are not correlated with match activities.     

Risk factors for musculoskeletal injuries in elite junior tennis players: a systematic review

The objective was to systematically review the literature on risk factors and prevention programs for musculoskeletal injuries among tennis players. PubmedMedline, Embase, CINAHL, Cochrane, SportDiscus were searched up to February 2017. Experts in clinical and epidemiological medicine were contacted to obtain additional studies.

For risk factors, prospective cohort studies (n > 20) with a statistical analysis for injured and non-injured players were included and studies with a RCT design for prevention programs. Downs&Black checklist was assessed for risk of bias for risk factors. From a total of 4067 articles, five articles met our inclusion criteria for risk factors. No studies on effectiveness of prevention programs were identified. Quality of studies included varied from fair to excellent.

Best evidence synthesis revealed moderate evidence for previous injury regardless of body location in general and fewer years of tennis experience for the occurrence of upper extremity injuries. Moderate evidence was found for lower back injuries, a previous back injury, playing >6hours/week and low lateral flexion of the neck for risk factors. Limited evidence was found for male gender as a risk factor.

The risk factors identified can assist clinicians in developing prevention-strategies. Further studies should focus on risk factor evaluation in recreational adult tennis players.     

Dimensional Stability and Moisture Properties of Gap-Fillers Based on Wood Powder and Glass Microballoons

ABSTRACT

Conservation of wooden objects exposed outdoors is extremely difficult and complex due to their constant exposure to fluctuating weather conditions and biological degradation. Filling the gaps in such objects requires the use of specific materials that in particular can adapt to changes in wood dimensions in response to humidity variations. Various materials have been used so far for filling voids in wooden artefacts but none of them was entirely suitable. Therefore, the authors have attempted to provide the basic characteristics of the selected commonly used filling materials based on pine wood powder or glass microballoons as fillers and Paraloid® B-72, Klucel® G, or glutin glue as binders, as the first step in research aiming at developing new and more appropriate gap-fillers. Special attention was paid to the dimensional stability of filling materials upon drying and exposure to water vapour and liquid water. The overall results indicate that among the examined fills those consisting of Paraloid® B-72 and glass microballoons revealed best properties as they were relatively dimensionally stable upon drying and exposure to moisture – despite high absorption of water – and were quite easy to finish. Generally, better properties were observed for filling materials containing higher concentrations of adhesives and these materials will be modified in the next step of the research. Since the main drawbacks of the examined gap-fillers were low water resistance, poor dimensional stability upon drying or exposure to water vapour or liquid water, and fragility or friability, future research into their modification will head towards improvement of the above-mentioned properties.     

An Introduction to Distributions Using Weighted Dice

This article describes a lively classroom demonstration that may be used to help develop students' understanding of the concept of a distribution, and to provide a foundation for the intuitive link between distributions and hypothesis testing.     

Rebels With a Cause? Adolescent Defiance From the Perspective of Reactance Theory and Self‐Determination Theory

The present investigation focused on adolescents' defiance against parents by drawing upon psychological reactance theory (Brehm, 1966) and self‐determination theory (Ryan & Deci, 2000). Psychological reactance would be elicited when freedom is taken away, thereby motivating individuals to engage in oppositional behavior. Throughout four studies (total N = 1,472, age ranging between 12 and 21 years), it was examined whether a controlling parenting style related to adolescents' experiences of autonomy need frustration (i.e., pressure) and reactance. Reactance, in turn, would relate to more externalizing and internalizing problems. Support was obtained for these associations in community and clinical samples, making use of different informants, and controlling for responsiveness and rule setting. A vignette‐based study provided further support. The discussion highlights theoretical and clinical implications.     

What's the Use of Use? : Return on Investment Strategies for Consortial DDA Programs

Column Editor's Note. This column focuses on formal collaboration and networking among libraries through consortia. It offers in-depth examinations of issues facing modern library consortia including (but not limited to) e-resource licensing, ebooks, next generation integrated library systems, shared print archiving, shared digital repositories, governance and other relevant topics. Contributions are accepted for this column and must be submitted to George Machovec (george@coalliance.org). Contact the column editor for suggested topics, deadlines and formatting.

ConnectNY has been involved in consortial e-book projects since 2010. Based upon the experience of these group e-book projects, we will explore different methods for assuming the shared cost of group e-book programs and then describe ways in which DDA programs may promote a positive Return on Investment (ROI) for groups as compared to individual institutions. We will argue that while use is a factor that can be taken into account when distributing cost amongst members, a budget-based percentage approach will allow consortia to effectively initiate and manage such projects over time.     

Inside the source selection process: Selection criteria for human information sources

Co-workers are an important source of information in organizations. Consequently, information managers seek to facilitate the use of such human information sources. Although various studies about what influences the use of human information sources in organizations exist, it is difficult for information managers to utilize insights from this research body. The studies have provided contradictory results regarding the role of accessibility and quality and suffer from various weaknesses. To address these weaknesses, several studies are employing other research methods. This study aims to contribute to the methodological development of this emerging new line of research by exploring the value of a think aloud approach to such studies. In addition, it aims to provide more insight into the role of accessibility and quality in the selection of human information sources in organizations. Fifty-six employees from four governmental organizations were asked to think aloud while selecting human information sources. The findings of this study corroborate those of studies taking a similar approach: source quality is the most dominant factor in the selection of human information sources. The think aloud approach seems a valuable contribution to available research methods to assess the role of accessibility and quality in human source selection in organizations.     

Keith Pavitt and the Invisible College of the Economics of Technology and Innovation

This paper uses a database on scientific interaction in the field of the economics of technological change and innovation. The database is used to address two issues. First, the network is shown to be (approximately) scale-free. This suggests that growth of the number of scholars active in the field and so-called preferential attachment (i.e., scholars entering the field prefer to attach themselves to highly reputable existing members of the network) are characteristic of the nature of the underlying field. Thus, increasing returns seem to govern mechanisms of reputation formation. Second, the potential existence of cohesive subgroups of relatively strongly connected scholars is explored, and the implications of this for the paradigmatic structure of the field are discussed.     

Topic Map as a Method for the Development of Subject Headings Vocabulary: An Introduction to the Project of the National Library of Poland

Subject searches in the National Library of Poland catalog are still comprised of a significant number of all searches, but understanding and exploration of the National Library of Poland Subject Headings causes many problems, not only for the end-users, but also for many librarians. Another problem in the National Library of Poland is the insufficient use of relationships between the terms. The solution could be a properly designed Web application based on a topic map using appropriate visualization that supports indexing and information retrieval in the National Library of Poland. The article presents the main stages of a planned project.