1,720,973 research outputs found
ODP Leg 160, Site 936/A tephra layers: new geochemical and chronological data of Quaternary explosive volcanic events.
No full textMajor and trace element characterization of tephra layers offshore Pantelleria Island: insights into the last 200 ka of volcanic activity and contribution to the Mediterranean tephrochronology
No full textA detailed tephrochronological study was carried out on the deep-sea core collected from Site 963A in the Sicily Channel during ODP Leg 160. The chronology of the succession is provided by an age-depth model based on isotope stratigraphy and quantitative eco-biostratigraphy. Major, trace and rare earth element content was obtained on single glass grains through electron probe micro-analysis and laser ablation-inductively coupled plasma mass spectrometry techniques from six well-preserved tephra layers, characterized by a discrete thickness found along the succession. These deposits were correlated with the volcanic activity of Pantelleria and dated at 42.5, 127.5, 128.1, 129.1, 188.7 and 197.7 ka. This detailed chemical characterization of the studied deposits aims to provide a valuable reference database for scientists working on both proximal and distal products erupted at Pantelleria island during the Late Pleistocene. This study, moreover, offers the opportunity to better identify Pantelleria-related marker tephras within the tephrochronological framework of the central and eastern Mediterranean area
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
Architecture of the NYT caldera and inner resurgent dome (Pozzuoli Bay, Campi Flegrei): new insights from seismic reflection and DInSAR data
No full textThe Campi Flegrei and its offshore prolongation (Pozzuoli Bay) are a volcanic area dominated by a collapse caldera
associated with the Neapolitan Yellow Tuff (NYT) eruption, occurred at ~15 ka BP, and by an intra-caldera resurgent
dome. We present new insights into: a) the geometry and kinematics of faults formed inside and at the edge of the caldera,
b) the architecture of the caldera and the resurgent dome, and c) the relationship between the structural elements of the
caldera and ground deformation. This work is based on the integration of single- and multi- channel seismic, swath
bathymetry data and ground deformation maps. The main results highlight that the NYT caldera, offshore, is characterized
by an ellipsoidal shape, elongated towards the ESE direction, with axes of ~8 km and ~7 km. It is bounded by a ~ 6 km
long and 1–2 km wide ring fault zone (RFZ) mainly consisting of an inward-dipping normal fault system and antithetic,
outward-dipping, faults. The sedimentary fill of the caldera is up to 60 m thick, and can be divided into six units,
characterized by different seismic facies, composition and depositional process. The inner-caldera resurgent dome, ~ 5
km in diameter, is limited by inner boundary of RFZ and consists in a broad antiformal structure with brittle deformation
localized in an apical graben. The base of the resurgence corresponds to the thalweg of the Epitaffio valley in the western
sector of the Pozzuoli Bay and the Bagnoli valley to the east. The maximum cumulative uplift of the resurgent dome is
~180 m while its average uplift rate is ~ 9–12 mm/year, between 15.0–6.6 ka BP. A subsidence of ~10 m is suggested by
the drowning of the infralittoral prograding wedge below the present-day storm wave base for the last 2 ka. The
deformation velocity pattern of the Campi Flegrei displays a radial symmetry centered around the Pozzuoli harbor. It is
possible to distinguish three almost-concentric sectors namely S1, S2, S3 with decreasing velocity from S1 (13-32
mm/year) to S3 (0.3-7.7 mm/year). The highest value (26-32 mm/year) is recorded at the Pozzuoli harbor. Sector S1 is
bounded by a NE–SW-trending fault to the west and NW–SE faults to the east. The data suggest that this sector coincides
with the resurgent dome of NYT caldera. The base of the latter corresponds to the faults bordering sector S1, and it can
be correlated with the base of the resurgence recognized offshore. Sector S2 represents a narrow strip located between
the base of the resurgence and the onland prolongation of the inner boundary of the RFZ. The results of our research
allow to define the stratigraphic architecture and the shallow structure of the NYT collapse-caldera in the Pozzuoli Bay.
Furthermore, they provide a base for the reconstruction of the resurgence geometry developed in the Campi Flegrei and
its offshore prolongation and additional constraints on the dynamics of magma chamber
Studio multidisciplinare di dati di carotaggi su alti strutturali della dorsale di Amendolara (Golfo di Taranto): risultati preliminari
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
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