1,721,002 research outputs found

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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

    Coarse-grained deltas approaching shallow-water canyon heads: A case study from the Lower Pleistocene Messina Strait, Southern Italy

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    The tide-dominated Messina Strait (southern Italy) is a 3 km wide marine passageway, whose block-faulted borders form steep subaqueous zones incised by canyons and gullies. These erosional features retreat towards the shorelines and are often in direct connection with subaerial valley-bounded river deltas. High-energy density-flows generated by river floods periodically enter the canyon heads, attaining supercritical-flow regime and accreting large, upslope-migrating bedforms. Although these bedforms have been documented in recent studies, little attention has been paid to the definition of the type of delta entering canyon heads, the internal features of river-influenced deposits accumulated in the nearshore zone, and their interplay with tidal currents flowing axially to the strait. This study focuses on a Lower Pleistocene coarse-grained succession exposed along the north-eastern margin of the modern Messina Strait, investigated using conventional facies analysis and sedimentological logging, integrated with photogrammetric techniques and interpretation of drone-acquired imagery. Facies confinement between basement blocks suggests a subaqueous delta complex shed from the tectonically controlled margin of the ancient strait and entering shallowly submerged canyon heads. Basal breccias, conglomerates and pebbly sandstones exhibiting channel-form discontinuities and upslope dipping backsets are interpreted as cyclic-step and antidune deposits. Units composed of these facies are comprised between master erosional surfaces and tidal ravinement surfaces. The tidal ravinements suggest that canyon infill occurred during a major phase of sea-level rise, punctuated by minor falls and stillstands. These surfaces are overlain by mixed bioclastic–siliciclastic, arenitic, trough and planar cross-strata, representing dunes migrating roughly parallel to the palaeo-coastline and originated by tidal currents amplified by the narrowing of the ancient Messina Strait. Tidal-influenced sedimentation dominated over the fluvial-influenced processes during the late transgression, overfilling the canyon relief. The exceptionally good exposure of depositional architectures and facies characteristics is key to outline the general features of a specific type of delta system, fed by valley-bounded rivers and entering canyon heads in the nearshore of tectonically-controlled, tide-influenced steep strait margins. The pre-existing subaqueous incised topography forced the delta front to be split into lobe branches during the canyon infilling, hampering clinoform architectures and preserving large supercritical-flow sedimentary structures. This study suggests these as possible criteria for the recognition of similar systems in outcrop or subsurface

    Variations on the Author

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    “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
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