1,720,954 research outputs found
Ecotoxicity Studies On Marine Sediments
Full text linkLe normative sull'ambiente in vigore in una Nazione vengono costantemente aggiornate, sia per l'arrivo sul mercato di nuovi composti (la cui tossicità deve essere prontamente testata) sia per le nuove conoscenze che si acquisiscono quotidianamente nel campo della salute. In Italia, un importante traguardo nella gestione ambientale è stato rappresentato dal Decreto Ministeriale n. 173/2016, che ha finalmente riconosciuto l'importanza dei test Ecotossicologici. Questi sono indispensabili e devono essere integrati con le analisi chimiche, al fine di definire la qualità dei sedimenti marini dragati.
Questo studio mirava a sviluppare un nuovo approccio per classificare i sedimenti qualora vi fosse stata, in un sedimento, una "non-corrispondenza" tra il rischio chimico e il rischio ecotossicologico. Spiegare questo disallineamento potrebbe trovare terreno fertile nell'evidenza che alcune molecole inquinanti non sono state prese in considerazione dal D.M. 173, come ad esempio gli ftalati. Dal punto di vista ecotossicologico, invece si deve ricordare che l'uso di test biologici era inizialmente finalizzato alla definizione di una perturbazione che si era già verificata nell'ambiente; invece oggi i test ecotossicologici vengono utilizzati insieme ai parametri chimici per avere un approccio predittivo: ovvero utilizzando le analisi come strumento di previsione per la valutazione del rischio ambientale e la classificazione delle diverse matrici. Sebbene l'uso di organismi viventi nei test di tossicità sia ben riconosciuto e ampiamente considerato da metodologie e protocolli sviluppati da numerose organizzazioni internazionali nel campo ambientale (es. EPA, ISO, ...), dovrebbe essere presa in considerazione la presenza di alcuni limiti di una certa rilevanza. La valutazione della tossicità è uno degli argomenti di discussione più attuali non solo nel mondo della ricerca, ma anche in quello politico-amministrativo: infatti, il problema di definire la tossicità di un campione è cruciale per stabilire criteri qualitativi e applicare programmi di risanamento e sanzioni amministrative. Per tutti questi motivi, i dati chimici ed ecotossicologici dovrebbero essere supportati da dati molecolari. In questo studio, i risultati ottenuti hanno chiaramente dimostrato l'idoneità dell'embrione di Crassostrea gigas quale eccellente modello sperimentale per ottenere prove chiare sulla tossicità degli elutriati di sedimento marino. Infatti, nonostante la mancanza di corrispondenza tra i dati chimici ed ecotossicologici per i tre sedimenti selezionati, che consentono di ipotizzare una differente tossicità, i risultati molecolari ottenuti suggeriscono fortemente la capacità di tutti i sedimenti di causare stress ossidativo nello sviluppo embrionale dell'ostrica. L'identificazione di biomarcatori molecolari nelle larve di C. gigas esposte a elutriati di sedimenti, potrebbe aiutare nella classificazione della qualità dei sedimenti e i risultati potrebbero essere l'integrazione con il comune approccio chimico ed ecotossicologico, migliorando significativamente il sistema di valutazione di qualità dei sedimenti. Inoltre, nonostante non richiesto dal decreto, è stata posta un'attenzione particolare alla rilevazione degli ftalati, esplorandone gli effetti - dovuti alla loro presenza ambientale - nell'orata, analizzando in modo particolare cosa causano sul metabolismo dei pesci: maschi adulti di Sparus aurata sono stati esposti, attraverso la dieta, a due dosi di DiNP, mostrando la capacità di questo composto di influenzare sia il metabolismo dei pesci che il sistema antiossidante. Le prove ottenute in questo studio suggeriscono fortemente alle agenzie ambientali che dovrebbe essere implementato l'elenco dei composti da monitorare e considerare, al fine di avere una migliore gestione ambientale.
Infine, i risultati ottenuti in questo studio usando un approccio integrativo hanno permesso di acquisire una conoscenza più approfondita della tossicità dei sedimenti, sia dal punto di vista chimico che biologico.Environmental laws in force in a country, constantly updated, both for the new materials presented in the market - of which non-toxicity must be proved - and for the new knowledge acquired in the field of health. In Italy, an important milestone in environmental management has been represented by the Ministerial Decree n. 173/2016, which finally recognized the importance of ecotoxicology in addition to chemical analysis. The necessity of integrating ecotoxicological data with chemical ones, in order to define the quality of marine dredged sediments deeply emerged. In fact, this study aimed at developing a novel approach to classify sediments when non correspondence between the chemical and ecotoxicological risk, identified by Decree n. 173, was found. From the chemical point of view, it could be done the fact that some polluting molecules have not been taken into consideration by D.M. 173, such as phthalates. On the ecotoxicological side, it must be remembered that the use of biological assay was initially aimed at defining a perturbation that had already occurred; instead today, in the D.M. 173, they are used together with the chemical parameters to have a predictive approach, using the analyses as a forecasting tool for the evaluation of the environmental risk and the classification of the different matrices. Although the use of living organisms in toxicity tests is well recognized and widely considered by methodologies and protocols developed by international environmental organization (ex. EPA, ISO, ...), the occurrence of some limitation, also of ecological relevance, should be considered. The evaluation of toxicity is one of the most current topics of discussion not only in the world of research, but also in the political-administrative one: in fact, the problem of defining the toxicity of a sample is crucial to establish qualitative criteria and apply remediation programs and administrative sanctions. For all these reasons, chemical and ecotoxicological data should be supported by molecular data. In this study, the results obtained clearly demonstrated the suitability of C. gigas embryo as an excellent experimental model to obtain clear evidence about elutriated toxicity. In fact, despite the lack of correspondence between chemical and ecotoxicological data for the three selected sediment, which let hypothesize their different toxicity level, the molecular results obtained strongly suggest the ability of all sediments to cause oxidative stress in developing oyster. The identification of molecular biomarkers in oyster larvae exposed to sediment elutriates, could help in the classification of sediment quality and the results could be to integrate with the common chemical and ecotoxicological approach, significantly improving the evaluation system. In addition, despite not requested by the decree, an additional focus on phthalate detection was laid, and the effects of their environmental presence was explored in seabream analysing the effects of their dietary administration on the fish metabolism: adult males of S. aurata were exposed, through the diet, to two doses of DiNP, showing the ability of this compound to affect both the fish metabolism and antioxidant system. The evidence obtained in this study, strongly suggest to environmental agencies that the list of compounds to be monitored and considered for a better environmental management should be implemented.
At the end, the results obtained in this study using an integrative approach allowed to gain a deeper knowledge on sediment toxicity, both from a chemical and a biological point of view
Dietary diisononylphthalate contamination induces hepatic stress: a multidisciplinary investigation in gilthead seabream (Sparus aurata) liver
No full textIn this study, adult gilthead seabream (Sparus aurata) were exposed for 21 days to Di-iso-nonylphthalte (DiNP at 15 and 1500 μg kg−1 bw day−1) via the diet. This plastic additive has been recently introduced to replace the di-(2-ethylhexyl)phthalate, the toxicity of which has been demonstrated conclusively both in vivo and in vitro trials. An analysis of a set of biomarkers involved in stress and immune response provides evidence of hepatic toxicity by DiNP in the present study. Both hsp70 and gr mRNA levels were upregulated significantly by DiNP, while plasma cortisol increased only in fish fed with the lowest DiNP dose. The oxidative stress markers g6pdh, glut red, gpx1 and CAT were upregulated by DiNP; gst mRNA was induced by the high dose and gck mRNA was downregulated significantly by the low dose. The mRNA levels of genes involved in the immune response, such as pla2, 5-lox, tnfa and cox2, were upregulated significantly only by the high dose of DiNP, while il1 mRNA increases in both doses. These molecular evidences were complemented with features obtained by Fourier Transform Infrared Imaging (FTIRI) analysis regarding the hepatic distribution of the main biological macromolecules. The FTIRI analysis showed an alteration of biochemical composition in DiNP samples. In particular, the low dose of DiNP induced an increase of saturated and unsaturated lipids and phosphorylated proteins, and a decrease of glycogen levels. The levels of caspase did not change significantly in the study, suggesting that DiNP does not activate apoptosis. Finally, the results also suggested the onset of hepatic oxidative stress and the activation of immune response, adding new knowledge to the already described hepatic DiNP toxicity
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
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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