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Tectonic accretion versus erosion along the southern Chile trench: Oblique subduction and margin segmentation
No full textThe southernmost tip of South America is an active continental
margin where oblique convergence between plates, transcurrent
motion, and tectonic rotation on land make the geodynamic
setting more complex than that of the central Andes. A
multichannel seismic data set has been used in conjunction with
multibeam and altimetry data to clarify the regional architecture
of the continental margin from 50°S to 57°S. Despite the thick
sedimentary section in the trench and the slow plate convergence
rate peculiar of typical accretionary margins, seismic reflection
profiles image widely varying frontal wedge morphologies,
different rates of accretion, a high degree of structural diversity,
and different modes of continental building (offscraping,
underplating, tectonic erosion). Correlation between structural
parameters (depth of the décollement level, width of the wedge,
accretionary rates, Moho depth) suggests large scale structural
control on margin geometry and structural diversity. The
transition from tectonic accretion to erosion and general
structural variations do not show any gradual trend, but rather,
they occur along oblique structural trends that produce a tectonic
segmentation of the margin. This is mainly related to tectonic
processes on the overriding plate (block rotations along
strike slip faults), while local disturbances on the incoming plate
(seamounts, fracture zones, and oceanic fabric relative
orientation) add further structural complexity. Altimetry data, in
conjunction with structural analysis, suggest that large scale
tectonic variations and structural development are related to
trench parallel gravity anomaly variations and, ultimately, to
basal friction on the plate interface. Strong negative gravity
anomalies are associated with sedimentary basins, wide wedges,
and accretionary domains, while positive gravity anomalies
mainly refer to transverse structural highs and narrow wedges
Passive subduction of the Phoenix plate remnant at the South Shetland trench, Antarctic Peninsula.
No full textGround Shaking Scenarios: The 8 September 1905 Earthquake in the Gulf of Sant’Eufemia, Offshore Western Calabria (Southern Tyrrhenian Sua, Italy)
No full text
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
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