1,720,958 research outputs found
Effects of selenate addition on selenium accumulation and plant growth of two Prunus rootstock genotypes
No full textA pot experiment was conducted with two Prunus genotypes (GF 677 and Mr.S.2/5, commercial rootstocks for peach), which are widely used in Italy and other European countries. Selenium (Se) was added as sodium selenate to 3-month-old micropropagated plants at a rate of 0 (control), 1.0, 2.5, and 5.0 mg Se (kg soil)–1. Plant growth, gas exchange, and Se accumulation were studied. Selenium added at a rate of 2.5 and 5.0 mg Se kg–1 appeared to be highly toxic for the two young peach rootstocks. Thirty-three days after the treatment, the plants showed a high mortality rate. The fast growing rootstock, GF 677, appeared to be more sensitive to Se toxicity, the mortality rate reaching 52%. The higher the Se concentration in the soil, the higher it also was in the plant. In general, both genotypes were able to take up Se and to translocate high amounts from root to leaf. After selenate addition to the soil, both GF 677 and Mr.S.2/5 plants showed reduced plant growth with the highest Se treatments. Furthermore, Se induced a partial stomatal closure, as evidenced by the values of stomatal conductance, resulting in a reduction in net assimilation, and thus a decrease in dry-matter production. Selenate applied at a low rate (1 mg Se kg–1) stimulated plant growth in GF 677. One year after the Se treatment, a remobilization of Se from the storage organs to the young shoots was detected. This study demonstrates genotypic variation in Se uptake and accumulation in peach rootstocks
Assorbimento e trasporto di selenato in piante di pomodoro in relazione al contenuto di solfato nel substrato di crescita
No full textUptake and distribution of selenium in tomato plants as affected by different concentration of sulphate
No full textSelenium uptake and partitioning in tomato plants in relation to sulphate concentration in soil
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
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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