1,720,962 research outputs found
Seep-carbonates from the Oltrepo Pavese area (Northern Apennines, middle-late Miocene)
No full textAccurate isotopic and facies analyses have been carried out on a marly-calcareous lens cropping out in the Voghera Apennine which contains a particular macrofauna. The data collected show that these carbonates can be interpreted as sedimentary products related to the expulsion of methane-rich fluids and cold-vent processes, analogous to modern sea-floor seep-carbonates. The facies distribution and cyclicity are indicative of different stages in seep-carbonate growth and, presumably, of variations in fluid flow intensity. Field observations have demonstrated the primary position of the carbonate lens, which is located on top of a lenticular level of resedimented sandstones and arenaceous siltstones (Serravalle Sandstones), partially corresponding in facies and age to the Termina Formation deposits of the Emilia Apennines. Stratigraphic data confirm that in the epi-Ligurian Sequence of the Northern Apennines sedimentary and/or tectonic conditions prone to the precipitation of seep-carbonates occurred only during the sedimentation of the basal part of the Termina Fm. (late Serravallian-early Tortonian). The close links between tectonic, sedimentary instability and deposition of seep-carbonates suggest that chaotic deposits of the Termina Fm., such as sedimentary melanges or debris flow deposits, could be reinterpreted in the light of mud diapirism
I carbonati autigeni di Cappella Monta (Miocene Medio -Sup., Appennino vogherese)
No full textFin dalla seconda metà dell’800 (Taramelli, 1877; 1882; Sacco, 1891) e successivamente in Sacco (1929) erano state segnalate nella zona dell’Oltrepo pavese alcune località fossilifere con faune a grandi bivalvi (calcari a Lucina). Nell’Appennino settentrionale depositi carbonatici di questo tipo sono presenti in successioni di età Miocene medio-sup. affioranti in differenti contesti geotettonici (Ricci Lucchi & Vai, 1994; Conti & Fontana, 1998; 1999), dai bacini satelliti (Successione epiligure) all’avanfossa (peliti di scarpata e depositi torbiditici). Tali depositi sono stati recentemente interpretati, grazie ad analisi geochimiche, paleoecologiche e sedimentologiche, come carbonati autigeni (chemioerme), la cui precipitazione è legata all’espulsione di fluidi freddi ricchi in metano (cold seeps). Vengono qui presentati i risultati delle analisi sedimentologiche, composizionali e geochimiche dell’ammasso carbonatico di Cappella Montà, tra gli abitati di S. Antonino e Mondondone (Appennino vogherese) che mettono in luce la natura metanogenica di tali carbonati autigeni a grandi bivalvi. Il rilevamento di dettaglio ha permesso inoltre di evidenziare che tale ammasso carbonatico è in posizione primaria ed è situato al tetto di un orizzonte di areniti risedimentate e di siltiti arenacee probabilmente correlabile per facies ed età a depositi che nell’Apennino emiliano sono stati inclusi entro la Formazione del Termina. Tale caratteristica lo rende estremamente interessante per lo studio di peculiari litofacies, in quanto sono solo pochi, limitati all’avanfossa appenninica e quasi sempre in posizione secondaria (risedimentati), gli esempi di carbonati autigeni impostati su un substrato composto da litologie grossolane (arenaceo-conglomeratiche)
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
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
A multidisciplinary study of middle Miocene seep-carbonates from the northern Apennine foredeep (Italy)
No full textSeveral pelitic intervals are intercalated at various levels within the marly-arenaceous turbiditic successions of the middle Miocene northern Apennine foredeep. They range in thickness from 30 to 200 m, and represent sedimentation on top of ephemeral structural highs related to blind faults. Sediments are made up of hemipelagites and fine-grained turbidites, and include C-13-depleted carbonates, related to the rising of methane-rich fluids (hydrocarbon seep-carbonates). Large portions of pelitic intervals are involved in chaotic masses by soft sediment deformation (slumps, slides, intraformational breccias), revealing an intense sediment instability during middle Miocene. A stratigraphic, mineralogic and geochemical study was conducted on two of these pelitic intervals (Castagno d ́Andrea, Mt Citerna) in order to reconstruct carbonate development, the composition of fluids, and to document the connections between fluid seepage and syndepositional tectonics. This multidisciplinary approach has allowed us to discriminate between the two examined pelitic intervals in terms of age, depositional rates and conditions, organic carbon and post-depositional processes. Seep-carbonates are characterized by chemosymbiotic fossil communities, autoclastic fractures and brecciation; carbonate bodies show complex facies relationships, as indicative of different stages in chemoherm growth. The compositional study evidences the peculiar chemistry of chemoherm carbonates (calcite low in Mg and Sr) compared with carbonates in associated enclosing pelites and with modern chemoherms, in general. The non-carbonate components within the chemoherms are enriched in detrital minerals and depleted in phyllosilicates with respect to the enclosing pelites. The mineralogical changes in the clay component within the brecciated unit of the Castagno d ́Andrea chemoherms suggest authigenic precipitation of the Mg-rich phases. Isotopic analyses show the distinct carbon signature in the chemoherms from the two examined intervals (Castagno d ́Andrea chemoherms more depleted, from - 15.8parts per thousand up to - 41.3parts per thousand PDB, than Mt Citema, from - 5.2parts per thousand up to - 16.7parts per thousand), and the transitional C-13-depletion trend observed moving from chemoherms to the enclosing pelites (moderately depleted) and Te (Bouma sequence) turbidites (in the range of marine carbonates). A slight but significant enrichment in delta(18)O (up to +1.4% PDB);is observed for all chemoherms when compared to values of carbonate phases present in enclosing pelites. Geochemical data indicate that the brecciated facies of seep-carbonates are related to an explosive release of gaseous fluids probably associated with the rise of deep hypersaline fluids
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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