118,257 research outputs found
Dynamic Control of Auxin Distribution Imposes a Bilateral-to-Radial Symmetry Switch during Gynoecium Development
No full textEvidence of synergistic/additive effects of sildenafil and erythropoietin in enhancing survival and migration of hypoxic endothelial cells
No full textEndothelial cell dysfunction is a common event to several pathologies including pulmonary hypertension (PH), which is often associated with hypoxia. As the endothelium plays an essential role in regulating the dynamic interaction between pulmonary vasodilatation and vasoconstriction, this cell type is fundamental in the development of vascular remodelling and increased vascular resistance.
We investigated the protective effects of sildenafil, a phosphodiesterase type 5 inhibitor, given in combination with erythropoietin (Epo) as it has been demonstrated that both drugs have anti-apoptotic effects on several cell types. Specifically, we examined the viability and angiogenetic properties of rat pulmonary artery endothelial cells upon exposure to either 21% or 1% oxygen, in presence of sildenafil (1 and 100 nM) and Epo (5 and 20 U/ml) alone or in combination (1 nM and 20 U/ml). Cell proliferation and viability were analysed by trypan blue staining, MTT assay and annexin V/PI stainings. In all assays the ability of the combination treatment in improving cell viability was superior to that of either drug alone. The angiogenetic properties were studied using a migration and a 3D collagen assay and the results revealed increases in the migration potential of endothelial cells as well as the ability to form tube-like structures in response to sildenafil and the combination treatment. We therefore conclude that both drugs exert protective effects on endothelial cells upon hypoxia, and that sildenafil enhances the migratory and angiogenetic properties, especially in hypoxic conditions. Furthermore, we present evidence of possible additive or synergistic effects of both drugs
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
The Role of Colour in Categorial Judgements
No full text Two experiments are reported that extend the findings of Ostergaard and Davidoff (1985) on the role of colour in object processing. Two types of categorial judgements were investigated from pictorial stimuli: size judgement and living/non-living classifications. The effect of real size on size judgements (Paivio, 1975) was replicated. It was found that colour did not affect either of the categorial judgements, but the facilitation occurring in object naming tasks was confirmed. It is argued that semantic judgements can precede name retrieval, that physical colour input does not enter the semantic system, and that the representation of object colour information in the semantic system may be largely verbal. </jats:p
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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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