1,720,967 research outputs found
Photoregulation of growth and branching of plum shoots: physiological action of two photosystems
No full textPlum shoot proliferation was investigated in terms of two distinct processes: axillary bud differentiation and axillary shoot development. Results showed that light quality influenced bud differentiation and interacted with apical dominance in determining shoot outgrowth, resulting in a differentiated structure of shoot clusters and type of branching. Results suggested that blue light, acting through its photoreceptor, increased the number of axillary buds differentiated from apical meristem, but did not remove the apical dominance. Red light removed apical dominance, while reducing the formation of axillary buds; both events appeared to be dependent on the putative amount of phytochrome active form, and independent of light photon fluence rate. On the contrary, blue light action appeared to be dependent on photon fluence rate. In addition, apparent blue-red interactions related to photomorphogenic events fit an antagonistic model for branching regulated by light via cryptochrome and phytochrome photoreceptors. Our results show that the dynamics of shoot cluster development is the product of two events: the formation of new axillary buds and their release from apical dominance
The effect of leaf age on CO2 assimilation and stomatal conductance of field-grown olive trees
No full textThe effect of leaf age on CO2 assimilation was measured in field-grown olive trees of cv. Frantoio over two growing seasons. Two to four age classes (from approx. 3-week old to 1-year-old) of fully-expanded leaves were measured in different periods of the year by infrared gas analysis. Maximum photosynthetic rates and stomatal conductance were measured in leaves between one and four months of age. CO2 assimilation tended to be lower in leaves of about 12 months or older. Differences depended on both and the environmental conditions prevailing when leaves had developed
Seasonal changes in the water relations of Mediterranean co-occuring woody species
No full textSeasonal and diurnal measurements of leaf water potential, stomatal conductance, and stem sap flow were made in adult plants of Arbutus unedo, Cistus monspeliensis, Erica arborea, Myrtus communis, Phillyrea latifolia and Quercus ilex growing under field conditions in coastal Tuscany for two years. Values of pre‐dawn leaf water potentials were higher than‐1.5 MPa for all species during most of the year. Minima of less than‐8 MPa were reached for E. arborea and C. monspeliensis in the summer, when those of P. latifolia and Q. ilex were‐5.0 and‐5.2 MPa, respectively. A high diurnal difference in leaf water potential was maintained in P. latifolia throughout the study period, including summer. During summer months, diurnal differences in leaf water potential were smaller in Q. ilex, M. communis and A, unedo than in P. latifolia, and virtually zero in E. arborea and C. monspeliensis. Stomata were closed in all species at the peak of stress. C. monspeliensis showed the highest stomatal conductance in the months prior to the onset of the drought period. Sap flow per unit leaf area of C. monspeliensis was two to three fold higher than those of M. communis and P. latifolia during periods of adequate soil moisture availability
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
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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