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Physiography and tectonic setting of the subglacial lake district between Vostok and Belgica subglacial highlands (Antarctica)
No full textWe present the interpretation of 11 radio echo-sounding (RES) missions carried out over the
Vostok–Dome Concordia region during the Italian Antarctic expeditions in the period 1995–
2001. The extension and the density of the radar data in the surveyed area allowed to reconstruct
a reliable subglacial morphology and to identify four relevant morphological structures namely:
the Aurora trench, the Concordia trench, the Concordia ridge and the South Hills. These
structures show evidence compatible with the presence of tectonic features. Morphological
considerations indicate their development in Cenozoic time. Hybrid cellular automata (HCA)-
based numerical modelling allowed to justify a possible role played by the tectonics of the
Aurora and Concordia trench evolution. This was accomplished by matching the bed profiles
along opportunely projected sections with the modelled surfaces as derived by the activity of
normal faults with variable surfaces within the continental crust. The Vostok–Dome C region
is characterized by a large number of subglacial lakes. From the analysis of basal reflected
power echo, we identified 14 new lakes and obtained information about their physiography as
well as their possible relations with tectonics.We propose a grouping of subglacial lakes on the
base of their physiography and geological setting, namely relief lakes, basin lakes and trench
lakes. Relief lakes located in the Belgica subglacial highlands and are characterized by sharp
and steep symmetric edges, suggesting a maximum water depth of the order of 100 m. Their
origin may well relate to localized, positive geothermal flux anomalies. Basin lakes located
in the Vincennes subglacial basin and are characterized by wider dimension that allow the
development of well-defined, flat ice surface anomalies. Trench lakes characterize the Aurora
and Concordia trenches as the possible effect of normal fault activity
Geological setting of the Concordia Trench-Lake system in East Antarctica
No full textThis study presents the interpretation of radio echo-sounding (RES) data collected during the
2003 geophysical campaign of PNRA (Italian National Research Project in Antarctica), which
focused on the exploration of the Concordia Trench-Lake system in East Antarctica. The data
allow us to identify a new lake (ITL-28) at the southern edge of the Concordia Trench and
a series of N–S trending subglacial troughs cutting through the Belgica Highlands. We have
mapped the bedrock morphology at 3 km resolution, which led to an improved geographical
and geomorphological characterization of the Concordia Trench, Concordia Ridge, Concordia
Lake and South Hills. Improved knowledge of the Concordia Trench allowed us to model
the 3-D geometry of the Concordia fault, suggesting that it played a role in governing the
morpho-tectonic evolution of the bedrock in the Dome C region, and to propose a Cenozoic
age for its activity. We recognize the importance of catchment basin morphology in hosting
subglacial lakes, and discuss the role played by tectonics, glacial scouring and volcanism in
the origin of the trench lakes, basin lakes and relief lakes, respectively
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
Radio Echo Sounding (RES) investigations at Talos Dome (East Antarctica): Bedrock topography and ice thickness
No full textRadio echo sounding measurements were collected during two Antarctic expeditions to determine the ice thickness and the sub-glacial morphology of Talos Dome in the region around 72°48′S; 159°06′E (about 6400 km2) on the edge of the East Antarctic plateau adjacent to Victoria Land in the western Ross Sea sector. The increasing interest in this region is due to the fact that in this area the ice accumulation is higher than in other sites in East Antarctica. Because of this, Talos Dome could be a new site for a project of a deep ice core drilling to obtain information on climate changes near the coast of Antarctica. In this frame, the knowledge of the bedrock topography is of great importance to choose the best location for the drilling site. In this paper, airborne radio echo sounding results from two Antarctic expeditions (1997 and 1999) are presented. Bedrock topography in bi- and three-dimensions for the Talos Dome region are discussed
Geological setting of the Concordia Trench-Lake System in East Antarctica
No full textThis study presents the interpretation of radio echo-sounding (RES) data collected during the 2003 geophysical campaign of PNRA (Italian National Research Project in Antarctica), which focused on the exploration of the Concordia Trench-Lake system in East Antarctica. The data allow us to identify a new lake (ITL-28) at the southern edge of the Concordia Trench and a series of N-S trending subglacial troughs cutting through the Belgica Highlands. We have mapped the bedrock morphology at 3 km resolution, which led to an improved geographical and geomorphological characterization of the Concordia Trench, Concordia Ridge, Concordia Lake and South Hills. Improved knowledge of the Concordia Trench allowed us to model the 3-D geometry of the Concordia fault, suggesting that it played a role in governing the morpho-tectonic evolution of the bedrock in the Dome C region, and to propose a Cenozoic age for its activity. We recognize the importance of catchment basin morphology in hosting subglacial lakes, and discuss the role played by tectonics, glacial scouring and volcanism in the origin of the trench lakes, basin lakes and relief lakes, respectively
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
Physiography and tectonic setting of the subglacial lake district between Vostok and Belgica Subglacial Highlands (Antarctica)
No full textWe present the interpretation of 11 radio echo-sounding (RES) missions carried out over the Vostok–Dome Concordia region during the Italian Antarctic expeditions in the period 1995– 2001. The extension and the density of the radar data in the surveyed area allowed to reconstruct a reliable subglacial morphology and to identify four relevant morphological structures namely: the Aurora trench, the Concordia trench, the Concordia ridge and the South Hills. These structures show evidence compatible with the presence of tectonic features. Morphological considerations indicate their development in Cenozoic time. Hybrid cellular automata (HCA)- based numerical modelling allowed to justify a possible role played by the tectonics of the Aurora and Concordia trench evolution. This was accomplished by matching the bed profiles along opportunely projected sections with the modelled surfaces as derived by the activity of normal faults with variable surfaces within the continental crust. The Vostok–Dome C region is characterized by a large number of subglacial lakes. From the analysis of basal reflected power echo, we identified 14 new lakes and obtained information about their physiography as well as their possible relations with tectonics.We propose a grouping of subglacial lakes on the base of their physiography and geological setting, namely relief lakes, basin lakes and trench lakes. Relief lakes located in the Belgica subglacial highlands and are characterized by sharp and steep symmetric edges, suggesting a maximum water depth of the order of 100 m. Their origin may well relate to localized, positive geothermal flux anomalies. Basin lakes located in the Vincennes subglacial basin and are characterized by wider dimension that allow the development of well-defined, flat ice surface anomalies. Trench lakes characterize the Aurora and Concordia trenches as the possible effect of normal fault activity
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
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