1,721,014 research outputs found
Delayed differential equation based study of sub-terahertz emission in multi-section quantum dot ring lasers
Full text linkWe present a study of the generation of subterahertz pulses in multi-section quantum dot (QD) ring lasers based on an improved version of the well-established delayed differential equation model, and taking into account an arbitrary number of gain and absorber sections. Results of the analysis of an 8-section ring laser emitting at 1.3 μm are presented. The proposed approach provides a significant insight for the understanding of the onset of the harmonic mode-locking in this family of devices and shows to be an effective tool for the optimization of the real devices in terms of pulses quality and generated RF intensity
A review of the classification systems for marine benthic habitats and the new updated Barcelona Convention classification for the Mediterranean
No full textThe Mediterranean Sea supports high levels of biodiversity and complexity but is facing increasing human pressures, so that strategies to protect and recover its ecosystems must be a priority in environmental policies. Benthic cartography represents the first step of marine spatial planning for the proper management and protection of our sea. Univocal habitat classification systems are thus needed to map, monitor, and inventory marine habitats, and to guarantee common and shared frames for a harmonized interpretation of the Mediterranean habitat types. In this paper we reviewed the existing classification systems of marine benthic habitats, to discuss the process of revision and updating of one of the first system developed under the Barcelona Convention (BC) in 1998 and adopted by all the Mediterranean countries. The BC classification was revised including the new habitats discovered in the last 30 years, and consistently with the criteria used to revise the EUropean Nature Information System (EUNIS), which is a comprehensive pan-European system for habitat identification. The updated BC classification is hierarchical with 5 levels, which allows representing the most suitable habitat level with respect to the restitution scale of the map. Each habitat is univocally identified by an alpha-numeric code, name and general description following the bionomic approach traditionally adopted in the Mediterranean benthic cartography since the late nineteen century. The new BC classification lists 128 main habitats up to the level 4, which may also contain sub-habitats at the level 5, i.e. associations and facies, totalising 394 habitat types (54% of new habitats with respect to the first BC classification). The updated BC classification system has been used for the selection of reference marine habitats that support two fundamental processes of environmental management: i) identification of Specially Marine Protected Areas according to the SPA/BD Protocol of Barcelona Convention; ii) selection of habitats to be monitored, as requested by the Integrated Monitoring and Assessment Programme and the European Directives (e.g., Water Framework and Marine Strategy). The new list of reference habitats, selected because of their high ecological and conservation value, contains 267 habitats, corresponding to 68% of the total habitats listed in the updated BC classification
Depth and substrate type driven patterns in the infralittoral fish assemblage of the NW Mediterranean Sea
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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