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Dormancy and germination in wheat embryos: ribonucleases and hormonal control
No full textAcidic and neutral ribonucleases (RNases) were studied in embryos of Triticum durum cv. Cappelli and the effects of
abscisic acid (ABA) and gibberellic acid (GA3) were analysed. RNases activities increased during germination and were
comparable in dormant and non-dormant embryos imbibed for 24 h. ABA generally inhibited ribonucleolytic activities,
while GA3 only affected dormant embryos. To assess whether changes in RNase activities during germination or
following hormonal treatment required new transcriptional or translational action, cycloheximide or cordycepin were
used. The action of inhibitors of acidic RNase activity was found only in non-dormant-embryos. Findings obtained in
the present work concur with a change of the ribonucleolytic pattern in the shift from dormant to non dormant
metabolism
Going 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
Esposizioni extraprofessionali ad amianto e tumori maligni della pleura nell'area di Livorno.
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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
Nucleolytic enzymes and DNA degradation in aleurone layers of imbibed aged wheat seeds
No full textDuring prolonged storage seeds progressively lose viability and as the rate of ageing is tightly linked to
conditions of storage in this work wheat seeds stored for different periods at different temperatures were used.
Seeds were categorised as viable, non-viable or of intermediate viability. The object was to determine whether
ageing is associated with changes in the activity of RNases and nucleases in the aleurone of wheat seeds. The
aleurone dies during post germination and this death appears to be programmed. As some plant nucleases are
involved in PCD, these enzymes were studied to follow aleurone cell fate during the imbibition of seeds with
different viability and stored at different temperatures. Worth noting was the appearance of a particular Zn2+-
dependent nuclease (p40) and of a DNA ladder pattern on the second day of imbibition for all materials used,
except for viable cold stored seeds, where Zn2+-dependent nuclease and DNA laddering appeared on the fourth
day of imbibition. Results obtained support the correlation between induction of nuclease activities (p40) and
DNA laddering. Ageing was characterised by the same pattern of changes with a more precocious degeneration
in less viable seeds. Cold storage seems to delay the DNA ladder in viable material
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