1,720,974 research outputs found
A multidisciplinary approach in recognizing seep-carbonates: A case study from the Loiano Formation (late Eocene) in the northern Apennines (Italy)
No full textThe Oligocene-Miocene volcanism in the Apennine: discovery and characterization of baryte and phillipsite-Ba rich bed in the lower part of the Ranzano Formation (Reggio Emilia, Italy)
No full textThis work reports the biostratigraphic assessment and the
chemical and mineralogical characterization of a zeolitized and
barium-rich volcanic pyroclastic bed outcropping in the lower Secchia
Valley (Northern Apennines, Italy), very close to the boundary between
the Ranzano and the Monte Piano Formations. To our knowledge, it
is the older so far documented in the Emilian Epiligurian Succession
as, through nannofossil biostratigraphy, we have documented an early
Oligocene age (Rupelian CNO1 nannofossil zone) for the enclosing
sediments. The chemical and mineralogical composition, the latter
obtained through a multi-analytical approach combining X-ray powder
diffraction (Rietveld-RIR method) with thermal analyses coupled
with evolved gas mass spectrometry, revealed large amounts of Barich phillipsite, baryte, volcanic glass and subordinate quantities of
sanidine and plagioclase; on the other hand, phlogopite, idiomorphic
plagioclase and femic minerals, frequently found in younger volcanic
layers of the Ranzano Formation, here are absent. The quantitative
mineralogical assessment together with mineral associations suggest
that diagenesis did not play a relevant role in the crystallization of
phillipsite, but its role cannot be neglected for the crystallization of
baryte. Hypothesis on the genesis and transformation of the original
material and on the possible correlation with the coeval calc-alkaline
magmatic sources in the circum-Mediterranean area were considered,
but no definitive conclusion has been reached
Composition of sands in cores along the high-speed rail (TAV): Preliminary indications on the sedimentary evolution of the Modena plain
Full text linkThe Modena alluvial plain has been geologically investigated in great detail and is characterized by a spectacular abundance of archaeological sites of various age. For this reasons the area may be considered a natural laboratory for the reconstruction of the recent sedimentary evolution of the Po Plain. The alluvial plain area examined for this study has an approximate extent of 150 km2 and is located at the northern side of the Northern Apennines thrust- and fold-belt, where streams draining the chain flow toward the northeast into the Po river. Detailed modal analyses by point-counting of thin sections show that modern stream sands in the Modena plain show similar overall compositional fields, but can be discriminated on the base of key-components, such as quartz, feldspar, carbonate and lithic fragments. The study of sand sediments indicates that the compositional fields have not varied significantly since the Neolithic. The only major diagenetic process is the formation of carbonate concretions (caliche), which can be easily recognized as secondary particles during point counting of thin sections. These results indicate that the reconstruction of the recent evolution of the local drainage system is possible by comparing ancient with modern fluvial sand compositions. The drilling of numerous wells along the new high speed train tract (TAV) provided us with new insight on the sedimentary evolution of the plain through time. The samples recovered from 6 wells reaching depths up to -50 m show that the sand sediments older than 10-12 kyr, have a significant shift in composition from the modern ones. This compositional change consists in a marked overall increase of quartz and feldspar components. The compositional variations can be explained by the combination of various factors: a) significant change in the bedrock lithology through time induced by tectonics and/or change in the local drainage pattern, and b) recycling of older fluvial sediments enriched in feldspar. Because the sands older than 10-12 kyr compared to the overlaying olocenic and modern sediments are enriched in feldspar, which is considered a particularly alterable component, the compositional differentiation can be related to effects induced to glacial-interglacial climate changes but not to post-depositional diagenetic processes. The considerable change in sand composition and the stratigraphy of the deposits suggest dramatic geographical, environmental and depositional variations supporting the observation that a regional unconformity separates the Late Pleistocene from the Olocene sediments
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
Note Illustrative della Carta geologica d'Italia alla scala 1:50.000 F. 237 Sasso Marconi, Servizio Geologico d'Italia - ISPRA
No full text<p>Note illustrative redatte per il Foglio geologico n. 237 Sasso Marconi della Carta Geologica d'Italia alla scala 1:50.000. 168 pp.</p>
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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