1,721,056 research outputs found
Localisation of nickel and mineral nutrients Ca, K, Fe, Mg with scanning electron microscopy microanalysis in tissues of the nickel-hyperaccumulator Alyssum bertolonii Desv. and the non-accumulator Alyssum montanum L
No full textPlants of the nickel-hyperaccumulator Alyssum bertolonii Desv. and of the non-accumulator A. montanum L. growing on a
serpentine site in Tuscany, Italy, and plants of A. montanum from a nearby non-serpentine site were analysed for metal
concentration and localisation. The leaves of A. bertolonii contained 160 times more nickel than those of A. montanum from
the same site, thus demonstrating its hyperaccumulation capacity towards this metal. On the other hand, both species
showed an inversion of the Ca/Mg ratio in their organs relative to the soil. Nickel localisation in plant tissues was examined
by Scanning Electron Microanalysis (SEM/EDX). In A. bertolonii, a specific pattern of nickel distribution was detected, with
the highest concentrations present in parenchyma and sclerenchyma cells for the roots; in the shoots, the highest amounts of
nickel were found in the stem epidermis, the leaf epidermal surface, and the leaf trichome base. This particular nickel tissue
distribution pattern was not found in the non-accumulator A. montanum growing on serpentine soil. Other mineral nutrients,
namely Mg, Ca, K, Fe, instead, had a similar distribution in the two species. The A. montanum plants from the nonserpentine
site had very low nickel levels in their tissues, and these were of the same magnitude as those found in A. bertolonii
plants grown in a greenhouse on commercial horticultural soil with low nickel concentration. In A. bertolonii plants, the
tissue-specific allocation patterns appeared to depend on the degree of nickel hyperaccumulation, which is, in turn, directly
linked to the soil characteristics
Dealing with Ni: comparison between a hyperaccumulator and a non-hyperaccumulator species of Alyssum on serpentine soils
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Metal localisation by SEM/EDX in a hyperaccumulator and a non-hyperaccumulator species of Alyssum living on a serpentine soil in Tuscany
No full textDispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
- …
