1,720,963 research outputs found
PDGF-B: The missing piece in the mosaic of PDGF family role in craniofacial development
Full text linkBackground: The platelet-derived growth factor (PDGF) family consists of four ligands (PDGF-A, PDGF-B, PDGF-C, PDGF-D) and two tyrosine kinase receptors (PDGFR-α and PDGFR-β). In vertebrates, PDGF signaling influences cell proliferation, migration, and matrix deposition, and its up-regulation is implicated in cancer progression. Despite this evidence, the role of each family member during embryogenesis is still incomplete and partially controversial. In particular, study of the role of pdgf signaling during craniofacial development has been focused on pdgf-a, while the role of pdgf-b is almost unknown due to the lethal phenotypes of pdgf-b-null mice. Results: By using a pdgf-b splice-blocking morpholino approach, we highlighted impairment of neural crest cell (NCC) migration in Xenopus laevis morphants, leading to alteration of NCC derivatives formation, such as cranial nerves and cartilages. We also uncovered a possible link between pdgf-b and the expression of cadherin superfamily members cdh6 and cdh11, which mediate cell-cell adhesion promoting NCC migration. Conclusions: Our results suggested that pdgf-b signaling is involved in cranial NCC migration and it is required for proper formation of craniofacial NCC derivatives. Taken together, these data unveiled a new role for pdgf-b during vertebrate development, contributing to complete the picture of pdgf signaling role in craniofacial development
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
The oxygen-assisted transformation of propane to COx/H2 through combined oxidation and WGS reactions catalyzed by vanadium oxide-based catalysts
No full textThis paper reports about the gas-phase oxidation of propane catalyzed by bulk vanadium oxide and by alumina- and silica-supported vanadium oxide. The reaction was studied with the aim of finding conditions at which the formation of H2 and CO2 is preferred over that of CO, H2O and of products of alkane partial oxidation. It was found that with bulk V2O5 considerable amounts of H2 are produced above 400 8C, the temperature at which the limiting reactant, oxygen, is totally consumed. The formation of H2 derived from the combination of: (i) oxidation reactions, with generation of CO, CO2, oxygenates (mainly acetic acid), propylene and H2O, all occurring in the fraction of catalytic bed that operated in the presence of gas-phase oxygen, and (ii) WGS reaction, propane dehydrogenation and coke formation, that instead occurred in the fraction of bed operating under anaerobic conditions. This combination of different reactions in a single catalytic bed was possible because of the reduction of V2O5 to V2O3 at high temperature, in the absence of gas-phase oxygen. In fact, vanadium sesquioxide was found to be an effective catalyst for the WGS, while V2O5 was inactive in this reaction. The same combination of reactions was not possible when vanadium oxide was supported over high-surface area silica or alumina; this was attributed to the fact that in these catalysts vanadium was not reduced below the oxidation state V4+, even under reaction conditions leading to total oxygen conversion. In consequence, these catalysts produced less H2 than bulk vanadium oxide
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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