1,720,988 research outputs found
Fish as bioindicators of brackish ecosystem health: integrating biomarker responses and target pollutant concentrations
No full textBiological responses and contaminant levels in biological tissues were investigated in fish specimens of grass goby (Zosterisessor ophiocephalus) collected in spring 2000 in a moderately polluted brackish ecosystem, the Orbetello lagoon (southern coast of Tuscany, Italy). The complexity of harmful effects that contaminants may cause in fish over time was assessed. General condition indices (somatic liver index, and gonadal somatic index), cytochrome P450 enzymes, acetylcholinesterase activity and ovarian morphology were integrated with the content of organochlorines (OCs-hexachlorobenzene, DDTs and polychlorinated biphenyls) in liver and ovaries and p-nonylphenol (NP) and lower ethoxylate (NPE(1-2)) content in muscle and ovaries as well. Samples collected from the western basin of the lagoon near the Orbetello sewage treatment plant had somatic liver index values and two P450 activities significantly higher than those collected from the same basin at the Albegna river delta and in the Ansedonia canal in the eastern basin (P PCBs > HCB) were particularly lower in samples from STP compared to levels detected in sites AC and AR. Light microscopy of ovaries revealed that although the gonads were sexually mature, the diameter of the oocytes and eggs was smaller than that commonly reported. High levels of M and NPs were, in fact, observed in grass goby ovaries, and the differences observed between acetylcholinesterase activities among investigated sites suggest exposure to insecticides as well. The integration of biological responses and contaminant tissue content reveals that certain areas of the lagoon are selectively impacted by various human activities and helps in distinguishing relationships between biological responses and contaminant load in the lagoon environment.Les réponses biologiques et les niveaux de contamination des tissus ont été recherchés dans des spécimens de gobies d'herbiers (Zosterisessor ophiocephalus) récoltés au printemps 2000 dans un écosystème saumâtre modérément pollué, la lagune d'Orbetello (côte sud de la Toscane). La complexité des effets nuisibles des contaminants sur les poissons est suivie au cours du temps. Des indices globaux (indice somatique hépatique, indice somatique gonadique), les enzymes du cytochrome P450, l'activité acétylcholinestérase et la morphologie de l'ovaire sont utilisés ainsi que le contenu organochloré (hexachlorobenzène, DDTs et biphényles polychlorinatés) du foie et des ovaires, les teneurs en p-nonylphénol et en éthoxylates inférieurs du muscle et des ovaires. Des échantillons provenant du bassin ouest de la lagune près de la station d'épuration d'Orbetello présentent, pour l'indice somatique hépatique et pour les deux activités P450, des valeurs nettement supérieures à celles qui sont relevées dans le même bassin dans le delta de la rivière Albegna et dans le canal Ansedonia dans le bassin est (P PCBs > HCB) sont particulièrement faibles au site « station d'épuration d'Orbetello » comparé à ceux des sites « canal Ansedonia » et « rivière Albegna ». L'examen microscopique des ovaires révèle que, même si les gonades sont sexuellement mûres, le diamètre des oocytes et des œufs est plus petit qu'habituellement. De hautes concentrations d'hexachlorobenzènes et de p-nonylphenols sont en fait observées dans les ovaires des gobies des herbiers et les différences entre les activités acetylcholinestérase des différents sites suggèrent une exposition aux insecticides. L'intégration des réponses biologiques et du contenu tissulaire en contaminants indique que certaines aires de la lagune subissent un impact sélectif des activités humaines. Ceci met en évidence les relations entre les réponses biologiques et la charge en contaminants dans l'environnement lagunaire
Foscolo e gli scritti sulle Isole Ionie
No full textIl saggio si concentra sugli scritti foscoliani per le Isole Ionie e sull’interesse per le vicende politiche dell’Eptaneso che si evidenzia anche nei rapporti epistolari con il conte Giovanni Antonio Capodistria. Nello Stato politico delle Isole Ionie emerge in particolare il rifiuto della soluzione insurrezionale in favore di una politica di compromesso volta a ottenere il maggior grado possibile di libertà nell’ambito della protezione britannica. Sull’esigenza di ottenere una Costituzione che rispetti le leggi e non dipenda esclusivamente «dall’arbitrio dell’Alto Commissario» Thomas Maitland insiste in modo più specifico lo scritto su Come ottenere modifiche alla Costituzione delle Isole Ionie, mentre le Idee sulla pubblica educazione nelle Isole individuano nell’unione di intenti dei cittadini e nel miglioramento della loro istruzione i principali strumenti di difesa dalle ingerenze straniere
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
First observation of histopathological effects of 2,4,6-trinitrotoluene (TNT) in gills of European eel Anguilla anguilla (Linnaeus, 1758)
No full textThe aim of the present study was to investigate the effects on gill morphology of the explosive 2,4,6-trinitrotoluene (TNT) in a model fish, the European eel, Anguilla anguilla (Linnaeus, 1758) to assess potential detrimental effects in marine fish due to its presence in dumping areas. Juvenile specimens of A. anguilla were exposed in vivo for 6 and 24 h to 0.5, 1 and 2.5 mg/l nominal concentrations of TNT using dimethyl sulfoxide (0.1‰) as solvent carrier. Histological analysis of gills indicated that TNT induced several structural lesions. After 6h of exposure at 0.5 and 1 mg/l TNT, oedema of some secondary lamellae was evident: this change at the highest dose of 2.5 mg/l led to epithelial lifting and detachment from the endothelium and rupture of the branchial membrane and vascular congestion. After 24 h at 0.5 mg/l, increased oedema in secondary lamellae, extensive epithelial detachment and vascular congestion and dilation of lamellar capillaries and pooling of blood at 1 mg/l were observed. At 2.5 mg/l, epithelial hyperplasia, fusion of adjacent lamellae, obliteration of interlamellar spaces by means of tight junctions were also observed. Moreover, chloride cells proliferated along secondary lamellae, and mucus hypersecretion was evident. The overall results clearly indicate that gills are sensitive targets of TNT. © 2008 Springer Science+Business Media B.V
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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