1,720,973 research outputs found
Vitis ×novae-angliae (Vitaceae): systematics, distribution and history of an “illegal” alien grape in Europe
No full textSystematics and distribution in Europe of Vitis xnovae-angliae (= V. labrusca x V. riparia, Vitaceae), a naturalized North American neophyte introduced for wine production in the 19th century, are investigated. Original identification tools are provided and diagnostic characters are discussed in detail, with special reference to leaf, fruit and seed morphology and the flavour of ripe berries. The complex of events that led to its introduction and eventually to its prohibition in Europe are also taken into account. Original morphological data regarding infructescences and seeds of related taxa are also reported
Translocation and monitoring of wetland plants.
No full textWet habitats are among the most threatened ecosystems all over the World and the importance of wetland protection is well recognized in several international treaties. Threats for wetlands are numerous; drainage in agriculture, use of water for the industry and agriculture, climate change-mediated drought or intrusion of salt water into freshwater wetlands, water pollution and eutrophication. Consequently, wetland destruction, fragmentation and degradation have led to negative direct and indirect impacts on wetland-dependent plants. Habitat protection, restoration or reconstructions are widely used ways to recover aquatic ecosystems. Habitat restoration and reconstruction require wetland plants to be translocated into restored sites or new sites. However, translocation of wetland plants can be very challenging because it also includes the water quality management. In many times, this is the most difficult part in translocation programs. Water quality can be assessed through the analysis of several physical and chemical variables and long time series of sampling is needed to obtain reliable data on water quality. In fact, while soil accumulates pollutants and nutrients, the concentration of pollutants in running water may reach high values during acute and shortlasting episodes, which makes them difficult to be detected. In some cases, also toxicological analysis may be needed to understand the thresholds of specific factors affecting the survival of the target species. In general, translocations require sound knowledge on species and habitats, like population dynamics, mating system and ability of dispersal. The selection and restoration of the target sites are one of the most important phases in a translocation program. Although different techniques are available to avoid mistakes in choosing the target sites, it must be considered that their selection should be quick and cheap. Here we present different approaches for the selection of suitable translocation sites for wetland-dependent plants species. Although several guidelines to translocation have been recently developed, few specific best practices for wetland-dependent plants are available. Thus, here we provide some practical advices and examples useful to improve the translocation success of wetland plants, from the preliminary phases of translocation to the monitoring program
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
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