1,721,004 research outputs found
Seismic velocity-depth relation in a siliciclastic turbiditic foreland basin: A case study from the Central Adriatic Sea
No full textStarting from reprocessed seismic profiles and borehole data, we investigate the Central Adriatic foredeep basin by deriving velocity depth trend of the Pliocene-Quaternary (PQ) siliciclastic succession (mainly composed by shales and sands). Relying on independent approaches to map two-way time (TWT) thickness of the PQ deposits, we converge on testing linear and exponential functions to predict VP depth trend. Results suggest that for large (>1500 m) thicknesses of the PQ deposits best fit is achieved by the exponential function VP(z) = c z(1-n) while for shallower and thinner deposits, a linear function like VP(z) = V0 + k z provides the best fitting estimates. We also investigate anomalies in velocity trend with depth and suggest that velocity drops observed within the PQ succession at significant depth (2500–3500 m) may reflect overpressured deposits. This hypothesis is consistent with the Apennine compression and high sedimentation rates in Central Adriatic during the Pliocene-Quaternary. Finally, we stress the importance of considering vertical-component phenomena and their time evolution when modeling foreland basins
High resolution DEM from stereopairs: examples from Nili Fossae and Gale crater, Mars
Full text linkIn this work, we present two Digital Elevation Models (DEM) obtained from stereopairs produced by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter (MRO). Target regions are chosen among the most intriguing and studied of Mars and are the western trench of the Nili Fossae and the northern portion of the central peak of the Gale crater. The terrains found in the first have proven to have a significant compositional variability whose spatial distribution is related to their morphology. The canyon found in the Gale crater is important to extend the comprehension of those geologic processes observed by the Curiosity rover, up to a distance and a morphologic context (the wall of the canyon) unreachable by the rover. The high resolution of the HiRISE images (0.25 m/pixel) from which we started allowed us to
produce the DEM with higher resolution and increased detail respect to the topographic model derived from the Mars Orbiter Laser Altimeter (MOLA) data
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
Gravity modeling reveals a Messinian foredeep depocenter beneath the intermontane Fucino Basin (Central Apennines)
No full textResidual gravity anomalies over Central Italy clearly indicate a prominent regional minimum over the Fucino Basin. Here, we forward model this anomaly along seven cross-sections. The modeling results validate the geometries and petrophysical properties of the Plio-Quaternary units previously proposed by reflection seismic data interpretation. Moreover, we suggest that a thick wedge-shaped sequence is present beneath the Plio-Quaternary post-orogenic units. Based on the inferred density and velocity properties, as well as outcrop evidence from around the Fucino Basin, this sequence would likely represent thick (~1700 m) siliciclastic syn-orogenic Messinian foredeep deposits. The proposed model implies a long-lasting tectonic inheritance history for the Fucino area, which originally hosted primary paleogeographic Mesozoic-Miocene boundaries. In the Messinian-Recent time, the Fucino has continuously represented a first-order tectonic depocenter for siliciclastic sediments, despite differences in tectonic regime (syn-orogenic Messinian, post-orogenic Plio-Quaternary) and palaeoenvironments (Messinian marine flysch, Plio-Quaternary alluvial-lacustrine facies). The compaction-corrected sedimentation rate (~0.89 mm yr−1), suggests a foredeep activity possibly spanning the entire pre-evaporitic, evaporitic and post-evaporitic Messinian time and is comparable to the sedimentation rate observed in the larger Pliocene Apennine foredeep, ~100 km northeast of the study area, suggesting a self-similarity of the belt-foreland system across time and space
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