1,720,957 research outputs found
Ostracoda and Mollusca biodiversity and hydrochemical features in Late Miocene brackish basins of Italy
Full text linkLate Miocene brackish ostracods and molluscs collected in three Italian basins show noticeable differences in their taxonomic composition, despite their capability of dispersing across wide geographic areas. In the Venetian-Friulian Basin (northern Italy), the upper Tortonian sediments contain oligotypic ostracod assemblages including Hemicyprideis dacica dacica, Hemicytheria pejinovicensis, and Loxoconcha cf. L. josephi and few gastropods referable to Planorbidae and Stenothyroides, which are typical of the central Paratethys. In central Italy, the brackish ostracods and molluscs recovered from upper Tortonian-lower Messinian deposits from four Tuscan basins (Volterra-Radicondoli, Velona, Baccinello-Cinigiano, and Valdelsa) display high affinity at a generic level but strong endemicity at a specific level. At Cessaniti (southern Italy), the upper Tortonian unit contains oligotypic brackish ostracods and molluscs: Mediocytherideis (Sylvestra) posterobursa, Cyprideis ruggierii, Loxoconcha cf. L. biformata, and Zonocypris membranae quadricella characterise the ostracod fauna, while Granulolabium bicinctum and Hydrobia frauenfeldi are the dominant molluscs. The recovered ostracods have a strong affinity with brackish species from central and eastern Palaeo-Mediterranean areas, whereas the molluscs present a Paratethyan origin. Despite the fact that the basins are all brackish and partly coeval, the systematics of these assemblages highlights the absence of common species among the three studied areas. Geochemical analyses (stable isotopes and trace elements) are performed on ostracods, and 87Sr/ 86Sr ratios are established in molluscs and echinoids. The results suggest brackish environments with different compositions and origins of solutes in the three different areas. The Tuscan basins are characterised by brackish waters, with NaCl-enriched waters coming from aquifers of Triassic evaporite bedrock. The brackish deposits of the Venetian-Friulian Basin and Cessaniti are true marginal marine environments, although the northern basin may have been influenced by both the Paratethyan Sava Basin and the northern portion of the Palaeo-Mediterranean water bodies. © 2012 Elsevier Masson SAS
Microborings in foraminiferi bentonici di un’area marina costiera altamente industrializzata: possibile correlazione tra infestazione microbica e inquinamento ambientale?
No full textNell’ambito di uno studio sulle comunità a foraminiferi bentonici provenienti da un’area marina costiera altamente industrializzata (Portovesme, Sardegna sud-occidentale) è stata osservata un’intensa attività microbioerosiva (immagini ESEM) sui gusci carbonatici, indotta da infestazione microbica (Cherchi et al., 2009).
La microbioerosione è particolarmente evidente nei campioni provenienti dai siti che presentano maggior tasso di inquinamento, più prossimi al Polo Industriale, mentre è più scarsa o assente nei siti meno inquinati o non inquinati situati in posizione più distale. L’impatto degli inquinanti (metalli pesanti fra cui Fe, Mn, Pb, Zn, Cd, polveri sottili ed emanazioni di CO2) è stato evidenziato attraverso analisi mineralogiche e geochimiche eseguite sui sedimenti di fondo e sui gusci dei foraminiferi mediante diffrazione a raggi X, analisi al SEM-EDS e via ICPMS, previa digestione del campione con le metodologie descritte da Cherchi et al. (2009). La risposta dei foraminiferi bentonici agli agenti inquinanti è stata valutata quantitativamente su base statistica (indici biotici e Q-mode Cluster Analysis). In particolare è stata evidenziata una forte correlazione positiva tra la concentrazione dei metalli pesanti e i valori di Equitability (J); mentre dalla Cluster Analysis è emersa una netta separazione tra siti altamente inquinati in prossimità del Polo Industriale e siti più distali meno inquinati.
La correlazione positiva tra dati biotici, mineralogici e geochimici ottenuti nell’area di Portovesme sembra suggerire l’ipotesi che lo stress ambientale, derivante dall’impatto degli agenti inquinanti, possa aver favorito l’instaurarsi di un microambiente estremo, atto allo sviluppo di comunità microbiche diversificate.
Risultati preliminari hanno evidenziato tracce bioerosive selettive su gusci porcellanacei e ialini prodotte presumibilmente da differenti microrganismi. Nei campioni analizzati i gusci ialini presentano una più intensa bioerosione sviluppata soprattutto intorno ai pori, che appaiono spesso deformati, stirati e tra loro fusi in plaghe irregolari, con tracce di dissoluzione. Effetti bioerosivi similari, attribuiti all’azione batterica, sono stati descritti da Freiwald (1995) in Cibicides lobatulus.
Il proseguo delle ricerche tenderà a definire: (i) la composizione delle comunità microbiche, (ii) la loro azione bioerosiva selettiva sulle diverse strutture dei gusci carbonatici e a fornire (iii) un contributo ai processi connessi alla loro biocorrosione
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
An Upper Miocene siliciclastic-carbonate ramp: depositional architecture, facies distribution, and diagenetic history (Capo Vaticano area, southern Italy)
No full textDispelling 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
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