1,721,270 research outputs found
Thymol and Thymus vulgaris extract protects human keratinocyte cell line (HaCaT) from UVA and UVB damage
Full text linkObjective: The aims of our study were to characterize ultraviolet (UV)A- and UVB-induced damages in a keratinocytes cell line (HaCaT), and to evaluate the protective capacities two plant-derivative compounds, namely Thymus vulgaris L leaf extract and thymol, its major component. A polyphenol rich diet has gained wide attention and it is now considered to be a protective agent for human skin, which can be over-exposed to environmental factors and in particular UV light.
Methods: Cells were pretreated for 1 h, in serum-free medium, with thymol (1 μg/ml) or Thymus vulgaris L (1.82 μg/ml) then exposed to different UVA (8-24 J/cm2) or UVB doses (0.016-0.72 J/cm2). Immediately after the UV exposure the intracellular redox status was evaluated by reactive oxygen species quantification and apoptotic events. Genotoxic aspects were evaluated 24 h after the end of irradiations using the alkaline comet assay and the immunostaining of phosphorylated H2AX histone protein (detected 1 h after the end of UV exposure).
Results: The pre-treatment of our experimental model with the two substances confirmed an antioxidant action and anti-apoptotic effect by reducing the cells percentage (sub-G1 phase). Furthermore, thymol and extract of Thymus vulgaris L were able to reduce genotoxic damage. The alkaline comet assay showed that the two substances were capable to decrease DNA damage. Also in this case, Thymus vulgaris L extract is more effective than thymol in decreasing genotoxicity markers.
Conclusions: Our results confirmed the more oxidant UVA and more genotoxic UVB effects. Regarding the protective effect of thymol and Thymus vulgaris L extract, data obtained proved their antioxidant and free-radical scavenging ability as known for phenolic (which our compounds belong to) and polyphenolic compounds. Thymol and mainly Thymus vulgaris L extract were also able to reduce the direct genotoxic damage
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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