1,720,966 research outputs found
The impact of propranolol, 17α-ethinylestradiol, and gemfibrozil on early life stages of marine organisms: effects and risk assessment
No full textPharmaceuticals are ubiquitously detected in the marine environment at the ng–μg/L range. Given their biological activity, these compounds are known to induce detrimental effects on biota at relatively low exposure levels; however, whether they affect early life stages of marine species is still unclear. In this study, a set of bioassays was performed to assess the effects of propranolol (PROP), 17-α ethinylestradiol (EE2), and gemfibrozil (GEM) on gamete fertilization and embryonic development of mussels (Mytilus galloprovincialis) and sea urchins (Paracentrotus lividus), and on the survival of seabream (Sparus aurata) larvae. Treatments of PROP (500, 5000, 50,000 ng/L), EE2 (5, 50, 500 ng/L), and GEM (50, 500, 5000 ng/L) were selected to encompass levels comparable or superior to environmental concentrations. Obtained data were tested for dose-response curve fitting and the lowest EC10/LC10 used to calculate risk quotients (RQs) based on the MEC/PNEC. No alteration was induced by PROP on the mussel gamete fertilization, while inhibitory effects were observed at environmental levels of EE2 (500 ng/L) and GEM (5000 ng/L). Fertilization was significantly reduced in sea urchin at all PROP and EE2 dosages. The 48-h exposure to all pharmaceuticals induced the onset of morphological abnormalities in either mussel or sea urchin embryos. Alterations were generally observed at environmentally relevant dosages, except for PROP in mussels, in which alterations occurred only at 50,000 ng/L. A decreased survival of seabream larvae was recorded after 96-h exposure to PROP (all treatments), EE2 (50–500 ng/L), and GEM (500 ng/L). A median RQ > 1 was obtained for all pharmaceuticals, assigning a high risk to their occurrence in marine environments. Overall, results showed that current levels of contamination by pharmaceuticals can impact early stages of marine species, which represent critical junctures in the resilience of coastal ecosystems
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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 Multixenobiotic resistance system as a possible protective response triggered by microplastic ingestion in Mediterranean mussels (Mytilus galloprovincialis): Larvae and adult stages
No full textThe emerging paradigm on plastic pollution in marine environments is that microsize particles (MPs) have far more subtle effects than bigger fragments, given their size range overlapping with that of particles ingested by filter-feeders. The impacts include gut blockage, altered feeding and energy allocation, with knock-on effects on widespread physiological processes. This study investigated whether ingestion of polystyrene MPs (PS-MPs) triggers protective processes in marine mussels. The Multixenobiotic resistance (MXR) system is a cytoprotective mechanism acting as an active barrier against harmful xenobiotics and a route of metabolite detoxification. Both larvae and adults were employed in laboratory experiments with different concentrations of 3-μm PS-MPs (larvae), and 3-μm and 45-μm PS-MPs (adults) matching size range of planktonic food through the mussel lifecycle. Embryos grown in the presence of 3-μm PS-MPs showed significant reduction of MXR activity and down-regulation of ABCB and ABCC transcripts encoding the two main MXR-related transporters P-glycoprotein and the Multidrug resistance-related protein, respectively. In adults, effects of PS-MPs were assessed in haemocytes and gills, which showed different modulation of MXR activity and ABCB/ABCC expression according to MP size (haemocyte and gills) or particle concentration (haemocyte). These data showed that modulation of MXR activity is part of a generalized response triggered by particle ingestion
Use of an integrated biomarker-based strategy to evaluate physiological stress responses induced by environmental concentrations of caffeine in the Mediterranean mussel Mytilus galloprovincialis
No full textThe occurrence of caffeine (CF), a biologically active drug, has widely been documented in coastal waters, and whether its environmental concentrations do represent a threat for marine organisms is unclear. The present study aimed at assessing sub-lethal effects induced by a 7-day exposure to environmentally relevant concentrations of CF (5, 50 and 500 ng/L) in the Mediterranean mussel, Mytilus galloprovincialis. CF in water and mussel tissues, and a battery of biomarkers, including lysosomal parameters of general stress, oxidative stress responses and endpoints of neurological and genetic damages, were evaluated and tested for significance vs controls (p < 0.05). CF exposure triggered a significant decrease of lysosomal membrane stability in both haemocytes and digestive gland (at 50 and 500 ng/L CF) and a significant increase of lysosomal content of neutral lipids (at 500 ng/L CF), indicating the onset of a stress syndrome. No effects were noted on lipid peroxidation parameters, such as malondialdehyde and lipofuscin content. The activity of the antioxidant enzymes glutathione S-transferase (GST) and catalase was unmodified in gills, while a significant increase of GST activity was observed in digestive gland (at 5 and 500 ng/L CF), suggesting the occurrence of GST-mediated phase II detoxifying processes. CF did not induce geno/neurotoxicity, as shown by the lack of effects on primary DNA damages and acetylcholinesterase activity. In line with its high hydrophilicity, CF did not bioaccumulate in mussel tissues. Data were integrated using the Mussel Expert System, which assigned a low stress level to mussels exposed to 500 ng/L CF, whereas no alterations of animal health status were highlighted at lower dosages. This study revealed a low profile of toxicity for environmental concentrations of CF, and confirmed the suitability of an integrated biomarker-based approach to provide a comprehensive picture of the degree of stress induced by emerging contaminants in marine invertebrates
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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
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