Hybrid clustering of multi-view data via Tucker-2 model and its application

With the modern technology fast developing, most of entities can be observed by different perspectives. These multiple view information allows us to find a better pattern as long as we integrate them in an appropriate way. So clustering by integrating multi-view representations that describe the same class of entities has become a crucial issue for knowledge discovering. We integrate multi-view data by a tensor model and present a hybrid clustering method based on Tucker-2 model, which can be regarded as an extension of spectral clustering. We apply our hybrid clustering method to scientific publication analysis by integrating citation-link and lexical content. Clustering experiments are conducted on a large-scale journal set retrieved from the Web of Science (WoS) database. Several relevant hybrid clustering methods are cross compared with our method. The analysis of clustering results demonstrate the effectiveness of the proposed algorithm. Furthermore, we provide a cognitive analysis of the clustering results as well as the visualization as a mapping of the journal set.     

Various aspects of interdisciplinarity in research and how to quantify and measure those

Scientometrics - Interdisciplinary research figures high on today’s policy agendas. This short introduction and overview sketches the complexity of defining and mapping the nature of...     

Is there a ��gender gap�� in authorship of the main Brazilian psychiatric journals at the beginning of the 21st century?

The aim of this study was to investigate the existence of a ??gender gap?? in the authorship of the four most important peer-reviewed psychiatric journals in Brazil and to quantify its magnitude. In addition, we examined the patterns of change in this gap during the period extending from 2001 to 2008 and variations according to the total number of authors, the type of article (original vs. non-original studies), and the journals themselves. A total of 1,036 articles were analyzed. We found that the proportion of female overall participation has increased from 2001 to 2008. Nevertheless, the incremental rate was accounted mostly by the growth of the participation in non-original articles. While the average annual increment for original articles was virtually null (.01%), for the non-original articles the corresponding figure was 3.7%. We also found that the chance of a woman being first author was about three times greater in original papers as compared to non-original ones at the beginning of the study period; this differential declined by 11% per year during this period. A different pattern emerged from the analysis of female last authorship. Year of publication and type of study were still associated with the chance of a woman being the last author but without interaction. Further, the journals themselves were found to be related with female last authorship: the chance of a woman being the last author in an article published in the Revista Brasileira de Psiquiatria was significantly smaller than in the other three journals. Our findings indicate clearly that some progress in being achieved in eliminating the gender gap also in field of Psychiatry and highlight the need for further research in this area.     

Opinion paper: thoughts and facts on bibliometric indicators

This paper aims at contributing to the on-going discussion about building and applying bibliometric indicators. It sheds light on their properties and requirements concerning six different aspects: deterministic versus probabilistic approach, application-related properties, the time dependence, normalization issues, size dependence and network indicators.     

Reduction of discrete element models by Karhunen–Loève transform: a hybrid model approach

The term “discrete element method” (DEM) in engineering science comprises various approaches to model physical systems by agglomerates of free particles. While shapes, sizes and properties of particles may vary, in most DEM models, particles are not confined by constraints, but subject to applied forces derived from potential fields and/or contact laws. This general approach allows for widespread use of DEM models for physical phenomena including gas dynamics, granular flow, fracture and impact analysis. However, its characteristic feature, combining particle restraints and forces into applied forces, does not only provide for flexible adaption of DEM to different physics, but also creates the most limiting restriction: Evaluation of the applied forces for each particle is computational expensive restraining the time sequence and sample size for numerical analyses. As an ansatz to circumvent this obstacle for a class of DEM models, we propose a model order reduction method based on coherency in the dynamics of particles. While initial flexibility of DEM is conserved, computational effort can be reduced significantly.     

National characteristics in international scientific co-authorship relations

The main objective of this study is the elaboration of national characteristics in internationalscientific co-authorship relations. An attempt is made to find statistical evidence of symmetry andasymmetry in co-publication links, of the relation between international co-authorship and bothnational research profiles and citation impact. Four basic types can be distinguished in the relativespecialisation of domestic and internationally co-authored publications of 50 most activecountries in 1995/96 concerning the significance of the difference between the two profiles.Co-publication maps reveal structural changes in international co-authorship links in the lastdecade. Besides stable links and coherent clusters, new nodes and links have also been found. Notall links between individual countries are symmetric. Specific (unidirectional) co-authorshipaffinity could also be detected in several countries.As expected, international co-authorship, on an average, results in publications with highercitation rates than purely domestic papers. However, the influence of international collaborationon the national citation impact varies considerably between the countries (and within oneindividual country between fields). In some cases there is, however, no citation advantage for oneor even for both partners.     

Sources and transport of selected organic micropollutants in urban groundwater underlying the city of Halle (Saale), Germany

In this study, we used isotopic (delta18O, delta2H, delta34S-SO4) and chemical tracers (boron) to assess the sources and transport processes of the micropollutants carbamazepine, galaxolide, and bisphenol A in groundwater underlying the city of Halle (Saale), Germany. Their ubiquitous presence in urban groundwater results from a combination of local river water infiltration, sewer exfiltration, and urban stormwater recharge. Attenuation during transport with infiltrating river water increased from carbamazepine (0-60%) to galaxolide (60-80%) in accordance with their increasing sorption affinity and decreasing recalcitrance against biodegradation. Distinctly higher attenuation during transport was found for carbamazepine (85-100%) and galaxolide (95-100%) if micropollutants originated from sewer exfiltration. Most likely, this is related to higher contents of organic matter and higher transit times of the respective flow paths. Although attenuation undoubtedly also affects the transport of bisphenol A, quantification is limited due to additional contributions from the urban stormwater recharge. As a consequence, micropollutant loads in groundwater indicate that groundwater discharge may dominate the export of bisphenol A from urban areas.