1,721,257 research outputs found
The in-vitro response of pollen germination and tube length to different types of acidity
No full textPollen germination and tube growth are among the most sensitive responses to atmospheric pollution. Both these are inhibited by the acidity of the growth medium. Pollen grains from two species (Pinus cembra L. and Sambucus nigra L.) were germinated in media over a range of pHs (5·0, 4·5, 4·0, 3·5, 3·0 and 2·5) and six types of acidity (H2SO4, HNO3, H2SO4: HNO3 in 1:1, 2:1, 3:1 and 5:1 ratio). Pollen of the Gymnosperm is shown to be more resistant to acidity in the medium. Sulphuric acid alone and the ratio 2:1 with nitric acid are demonstrated to be the more harmful for P. cembra and S. nigra, respectively. The latter species was sensitive to all mixtures, particularly in respect to germination percentage
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
Pre-exposure to ozone predisposes oak leaves to attacks by Diplodia corticola and Biscogniauxia mediterranea
No full textSelvicoltura e protezione delle foreste: risultati e prospettive del III Congresso Nazionale di Selvicoltura
No full textEarly responses to acute ozone exposure in two Fagus sylvatica clones differing in xeromorphic adaptations: photosynthetic and stomatal processes, membrane and epicuticular characteristics
No full textTwo Fagus sylvatica L. clones were used
to investigate the early responses to acute O3
exposure (150 nL L−1, i.e., 1.35× ambient hourly
peak in rural Italy) and whether xeromorphic adaptations
affect gas exchange, membrane, and epicuticular
responses. One clone originated in a wet and
temperate climate in Central Italy (Tuscany); the
other clone originated in a warmer and drier climate
in the southern-most part of the F. sylvatica distribution
(Sicily). Because of higher base gas exchange
rates, the most negative effects of O3 exposure (gas
exchange impairment, uncoupling between net photosynthesis
and stomatal conductance, increased
membrane lipid peroxidation) were found in the
southern clone. Xeromorphic adaptations (higher
epicuticular waxes and stomatal density, lower leaf
wettability and size) were found in this clone. Our
results suggest that xeromorphism may increase O3
sensitivity in species not adapted to face water stress,
like the mesophilic F. sylvatica, when experiments are
carried out with full irrigation. We present evidence
describing the relationship between gas exchange and
number and status of stomata. Stomatal density and
the structural damage to stomata resulting from O3
exposure did not affect gas exchange: In fact, nonstomatal
limitations to photosynthesis prevailed over
stomatal limitations
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