1,721,187 research outputs found
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
Blue light induced differentiation in Phycomyces blakesleeanus : The Blue Light Syndrome
No full textWe have heard at this conference that blue light has several effects in many plants and microorganisms. Blue light has several physiological effects in the same organism: Phycomyces blakesleeanus. The oldest effects known are phototropism and a light-induced growth response (for a review see Bergman et al. 1969; Russo and Galland 1979). For thirty years it has been known that blue light also induces β-carotene (Garton et al. 1951). A few years ago Bergman (1972) showed that short pulses of blue light on a growing mycelium leads to an ordered spatial distribution of the production of sporan-giophores. We have further investigated the action of blue light on the differentiation of Phycomyces
Poly(epsilon-caprolactone)-poly(fluoroalkylene oxide)-poly(epsilon-caprolactone) block copolymers as surface modifiers of poly(vinyl chloride)
No full textBlends of poly(epsilon-caprolactone)-poly(fluoroalkylene oxide)-poly(epsilon-caprolactone) (PCL-PFPE-PCL) triblock copolymers (with different length of PFPE and PCL segments) and poly(vinyl chloride) (PVC) were prepared by casting from tetrahydrofuran solution. DSC analysis revealed a complex morphology deriving from miscibility between PCL and PVC segments. XPS analysis showed strong surface enrichment of PFPE segments for all films prepared. Treatment with a PFPE selective solvent showed that the fraction of PCL-PFPE-PCL removed from surface decreased with increasing length of PCL blocks, indicating an anchorage effect by PCL segments with respect to PVC matrix
Unsaturated polyester resins modified with poly(epsilon-caprolactone)-perfluoropolyethers block copolymers
No full textPoly(epsilon -caprolactone)-perfluoropolyether-poly(epsilon -caprolactone) block copolymers (TXCL) synthesised from Fomblin Z-DOL TX (TX) have been mixed with conventional unsaturated polyester resins (UPR) to prepare fluorine modified UPR (FUPR). A preliminary investigation on the compatibility of uncured FUPR systems has shown that the presence of PCL blocks leads to an enhancement of compatibility with respect to pure perfluoropolyether macromers. The compatibility tends to decrease by increasing the TXCL concentration in the mixture depending on both molecular weight and TX/PCL ratio. Also the morphology of FUPR after curing was strongly affected by the rate of curing and by a critical balancing of TX/PCL ratio and molecular weight of TXCL copolymers. Both transparent and opaque FUPR were obtained for the same composition at different curing rates; high curing rates (i.e. high concentration of initiator/activator) favoured the formation of transparent FUPR through a kinetic control of phase separation. Scanning electron microscopy (SEM) analysis was in good agreement with the macroscopic results obtained by visual inspection. XPS analysis showed a very strong surface enrichment in fluorinated segments, which increases by increasing the TX/PCL ratio. Mechanical tests showed a slight plasticization effect (compared to UPR control) together with a very strong improvement in the absorbed energy at break EB showing the best toughening effect for TXCL with intermediate TX/PCL ratio. Finally, a minimisation of the water diffusion coefficient value (five times lower than UPR control) was noted for UPR modified with TXCL having intermediate PCL segment length. (C) 2001 Elsevier Science Ltd. All rights reserved
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