1,721,046 research outputs found
Cenozoic structural and stratigraphic history of McMurdo Sound, Antarctica
No full textDuring the austral summer of 2004 the RVIB Nathanial B Palmer (NBP0401) collected 2000 km of multi-channel and 500 km of single-channel seismic data over the Terror Rift and western Victoria Land Basin (VLB), McMurdo, Antarctica. Data were collected to expand marine and ice-shelf seismic coverage of McMurdo Sound to enable the recognition of basin-wide climatic and tectonic events through analysis of sub-surface horizons.
Collected data were integrated with existing reflection data from McMurdo Sound and with age data from Cape Roberts (CRP) and CIROS holes. The stratigraphic framework developed is based on distinct, regionally traceable horizons that correspond to significant and recognizable changes in glacio-marine sequence geometry and can be interpreted as recording basin-wide climatic and tectonic events for the period 0-17 Ma. Older sequences cored at CRP and CIROS could not be mapped since they are below the seafloor multiple.
The lowermost stratigraphic unconformity event interpreted (H10, 17 Ma from CRP) can be traced for many kilometres in both coast-parallel and coast-normal directions. Above this boundary the seismic data reveal a sedimentary succession in the Erebus Moat that reaches up to at least 3 km in thickness. Seismic horizons and units were correlated with tectonic rifting and loading episodes of the VLB, Terror Rift and Ross Island, as well as the Antarctic's fluctuating glacial history to resolve a depositional history over time. Formation ages were estimated for six horizons based on correlation with tectonic and climatic events. Deposition geometries and seismic facies observed reveal; (1) changing influences on accommodation space production, including extension of the VLB and Terror Rift, and loading of Ross Island, (2) a progressively cooling glacial/interglacial depositional environment since 17 Ma, and (3) changing glacial erosion patterns possibly due to the influence of Ross Island. Inferred sedimentation rates and facies patterns in McMurdo Sound support the existence of a stable East Antarctic ice-sheet since the Mid-Miocene
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
3-D Velocity Structure of the Northern Hikurangi Margin: Implications for Crustal Growth
No full textOnshore-offshore wide-angle seismic reflection and refraction data are combined with multi-channel seismic reflection profiles to model crustal structure within a 32,000 km2 block of the northern Hikurangi subduction margin, New Zealand. A 3-D onshore-offshore dataset comprising ~250,000 seismic traces is analysed as a suite of 81 receiver-gathers. These receiver-gathers contain reflected and refracted arrivals
and constrain a 3-D P-wave velocity forward model. Southwest along the strike of the subduction zone, velocity forward models resolve a
> 10 km increase in Moho depth and a > 20 km increase in basement thickness between Raukumara Basin and the Raukumara Peninsula. Beneath the topographic crest of the East Cape Ridge and Raukumara Peninsula, low velocities (3.0-5.0 km/sec) are resolved within a triangular prism (> 200 km3 /km-1 ie per km of strike)
positioned on top of the subducting slab. The arcward/inboard edge of this prism coincides with the intersection of the subducting slab with the Moho and southward along East Cape Ridge, both the prism and topographic crest are observed migrating arcward, concomitant with the increase in Moho depth beneath the continental shelf.
Second-order seismic-stratigraphic sequences within Raukumara Basin record a southeast-northwest migration of the Neogene depocenter. Internal deformation increases east and south of the central basin at East Cape Ridge and within the continental shelf where strata tilt up toward the topographic crest. Refracted arrivals place the first controlled-source seismic constraints on the
thickness of the about-to-be subducted northern Hikurangi Plateau. The Hikurangi Plateau crust is modelled as two layers with velocities of 4.9-6.3 km/sec and 7.1-7.3 km/sec with a combined thickness of 17-18 km. The upper 10 km of the subducting mantle lithosphere is modelled with velocities of 8.1-8.4 km/sec. The geometry of
the plate interface is also constrained by wide-angle reflections. Low velocities (3.0-5.0 km/sec) beneath the topographic crest of the East Cape Ridge and the Raukumara Peninsula are interpreted as underplated sedimentary and crustal
material and a rate of accretion of 10-25 km3 Myr-1 km-1 is calculated. The migration of the Neogene Raukumara Basin depocenter and what is considered postdepositional internal deformation are associated with uplift and protuberant growth at East Cape Ridge and Raukumara Peninsula in response to lower crustal underplating. The underplating process appears modulated by Moho depth and a cyclical crustal dynamic is proposed to provide a viable means of maintaining or increasing the netvolume of the forearc in the presence of trench slope collapse and subduction
erosion. At present, a discrepancy exists between published estimates of continental creation at volcanic arcs and continental destruction at subduction margins. Nd isotopic evidence and continental freeboard arguments require a constant volume of continental crust throughout the Phanerozoic. The crustal dynamic developed in this thesis highlights the importance of lower crustal underplating as a means of retaining
subducted sediment within the forearc, thus reducing the flux of continental material to the mantle. The calculated rates at which subducted sediment is underplated and accreted to the upper plate (10-25 km3 Myr-1 km-1) are considered sufficient to solve the discrepancy between the inputs and outputs at subduction margins within
analytical uncertainty
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