1,721,059 research outputs found
Multichannel seismic reflection and wide-angle and refraction data acquisition along the Iberia Atlantic Margins
Full text linkThe data acquisition contract was awarded to GECO-PRAKLA and took place in August-September 1993 aboard M/V Geco Sigma. Seismic data was successfully collected along the Cantabrian Margin, Galicia Margin, Iberian Abyssal Plain, the continental platform of Western Iberia, Tagus Abyssal Plain, the Gorringe Bank and Gulf of Cadiz. Data for the 240 km long line IAM-12 was acquired in February 1993 by SEISQUEST vessel of GECO-PRAKLA. The total amount of seismic reflection data collected was 3808.175 km in 19 track lines offshore. Technical specifications of the profiles: Streamer length 4800 m, Number of channels 192, Group interval 25 m, Shotpoint interval 75 m (100 m and 150 m on line IAM-2W), Source 7424 in3 (Record length 25 seconds), Sample rate 4 ms. Contact person: Torne, M., [email protected] Iberian Atlantic Margins (IAM) project is a multinational research programme, coordinated by the Institute of Earth Sciences of Barcelona, CSIC (Spain). It involves different academic institutions of Britain (University of Oxford and University of Durham), France (IFREMER), Portugal (University of Lisbon and Institute of Meteorology of Lisbon) and Spain (Institute of Earth Sciences of Barcelona, CSIC) and more than 40 associated scientists of European institutions attached to the main contractors. The project, financed by the European Community within its JOULE-Programme (Contract# JOU2-CT92-0177), aims to explore the deep continental and oceanic Atlantic margins of Iberia for a better understanding of the formation and evolution of Atlantic type margins, outstanding structural features and potential location of hydrocarbons and other natural resources. The project was designed to acquire deep seismic multichannel data and onshore recording of wide angle and refraction data along the North Iberian margin; the West Iberia margin, including the Galicia margin, the Iberia and Tagus abyssal plain, and the continental shelf off Portugal; and the Gorringe Bank region and Gulf of Cadiz. The experimental part of the study consisted of the acquisition of over 3700 km of near vertical incidence deep seismic multichannel reflection data. This together with wide angle reflection and refraction data recorded by land stations and OBS (Ocean Bottom Seismometers) has resulted in a full coverage in terms of crustal structure and velocity information of the study region.Peer reviewe
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
NEW CONSTRAINTS ON CRUSTAL STRUCTURE AND UPLIFT OF THETRANSANTARCTIC MOUNTAINS FROM GRAVITY DATA
No full textTransantarctic Mountains Uplift revisited with Gravity data and Flexural modelling
No full textThe Transantarctic Mountains (TAM) are often regarded as the uplifted flank of the West Antarctic Rift System (WARS). The TAM are, however, higher, longer and wider compared to other rift flanks. Unravelling the processes responsible for these unique characteristics, requires an improved knowledge of the deeper crustal architecture and uplift mechanisms of the TAM. Limited wide-angle and passive seismic data have provided important insights into the boundary between East and West Antarctica, but TAM uplift mechanisms have remained both controversial and poorly constrained. We present new models for the crustal structure and uplift mechanisms over the Victoria Land part of the TAM, based on a new compilation of gravity data, including data from the adjacent Ross Sea Rift (RSR) and Wilkes Subglacial Basin (WSB). To reduce inherent ambiguities associated with gravity modelling, we also incorporated independent wide-angle and passive seismic constraints onshore, and existing seismic reflection interpretations within the RSR. Our preferred model indicates that the crust under the TAM is 40±2 km thick, while the crust under the WSB is 33±3 km thick. A ca 5-7 km-thick root is imaged under the TAM. We propose that the root may be inherited from Ross-age orogenic events that thickened the crust. The high apparent density of the root implies a reduced buoyancy, such as inferred over several old mountain belts, including the Urals, the Caledonides of eastern Greenland, and older Proterozoic orogens. Additional thickening of the dense root may reflect later underplating processes, either linked to Jurassic magmatism, or alternatively to Cretaceous-Cenozoic rifting. Our flexural models demonstrate, however, that root preservation and magmatic underplating alone cannot explain all the TAM elevation. We show that 2/3 of the elevation arise from the combined effect of mechanical unloading along the TAM rift flank, erosion, and thermal uplift due to warmer upper mantle underlying the WARS. Preliminary 3D flexural modelling suggest that although these mechanisms may broadly explain the TAM, significant differences in rift structure, inheritance, mantle flow and erosion histories need to be taken into account to explain the observed segmentation of the range
Using new airborne gravity data to evaluate uplift mechanisms for the Transantarctic Mountains
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