1,720,957 research outputs found
Morphophysiological markers apt to individuate different susceptibility of pear rootstocks cultivated in 'in vitro' iron-deficient conditions
No full textIn many deciduous fruit trees species lime-induced chlorosis represents a serious economical damage. It may be overcome by agronomic strategies, as the use of tolerant rootstocks, valid alternative to reduce expensive iron-chelate fertilisation and chemical environmental impact. Since few years in vitro culture technique is applied to test rootstocks for iron chlorosis susceptibility. Micropropagated shoots were used for screening of quince rootstocks MA and BA 29, and pear cv. Conference under stress conditions on MS medium supplemented with different concentrations of FeNaEDTA, 100%=0.1 mM Fe (FeN) and 15%=0.015 mM (Fe15), and/or potassium bicarbonate, 0 mM (FeN) and 1 mM KHCO3 (FeNC and Fe15C). After 24 days, substrate pH, shoot growth markers, total leaf iron and photosynthetic pigment contents were determined. The medium pH reduction resulted similar among genotypes but different among treatments. Iron deficiency and high bicarbonate concentration induced different growth performances among the genotypes, reflecting a different sensibility and plastic adapation to the induced iron chlorosis. Total leaf iron content decreased in all genotypes, when iron deficiency and bicarbonate concentration increasing onto the medium, although pear cultivar showed more slight reduction. Photosynthetic pigments, analysed by HPLC, decreased in all type of stress, and the lowest levels were detected in Fe15C treatment, except for cv. Conference. A similar trend was exhibited by carotenoids, in particular by Violaxanthin.
Our preliminary data confirm the potential of in vitro culture as a rapid screening method. The choice of markers and the result interpretation will be deeply discussed in the paper
Iron acquisition and chlorosis susceptibility in different Fe-deprived quince and pear rootstocks
No full text
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
Pear plantlets cultured “in vitro” under lime-induced chlorosis display a better adaptive strategy than quince plantlets
No full textIn many fruit trees species lime-induced chlorosis causes serious economic damage. In the last few years, the in vitro culture technique has been applied to test rootstocks for susceptibility to iron chlorosis and to study biochemical and molecular aspects of the syndrome. In this study in vitro shoot cultivation of quince rootstocks MA, BA29 and pear cv. ‘Conference’ was used to unravel the relationship between iron deficiency, presence of bicarbonate, and
growth development and chloroplast pigment behaviour.
Stresses were obtained by using MS medium
supplemented with various concentrations of FeNa-
EDTA and/or KHCO3. Substrate pH, shoot growth and development parameters, total leaf iron and photosynthetic pigment contents of plantlets were independently determined after 24 days of culture. The medium was acidified by the species under all
stress conditions. Iron deficiency and bicarbonate
condition led to different growth patterns and modular
development among the genotypes. This reflects
a different sensitivity and plastic adaptation to the
elements of this stress. Iron concentration in leaves
and the shoot apex of plantlets decreased in all
genotypes. However, chloroplast pigments only
decreased in quince plantlets under iron deficiency
and bicarbonate condition while they did not change
in pear plantlets. Our results demonstrate firstly that a plantlet without a root system, which is cultivated in vitro, is able to sense iron deficiency and bicarbonate enriched conditions and, consequently, activates biochemical and physiological responses. Secondly, acidification appears to be related to iron concentration in tissues of quince rootstocks and pear cultivar.
Finally, chloroplast biochemical elements are
strongly and differently regulated under both stress
conditions and between genotypes
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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