1,720,968 research outputs found
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
A threshold in submarine channel curvature explains erosion rate and type
Get PDFSubmarine channels are conduits for sediment-laden flows called turbidity currents, which play a globally significant role in the offshore transport of sediment and organic carbon and pose a hazard to critical seafloor infrastructure. Time-lapse repeat surveys of active submarine channels have recently shown that upstream-migrating knickpoints can dominate channel evolution. This finding contrasts with many studies of ancient outcrops and subsurface geophysical data that inferred channel bends migrate laterally, as occurs in meandering rivers. Here, we aim to test these two contrasting views by analysing two high-resolution repeat seafloor surveys acquired 13 years apart across the entirety of an active submarine channel in Knight Inlet, British Columbia. We find that two main mechanisms control channel evolution, with the normalised channel radius of curvature (specifically, R* - channel radius of curvature normalised to channel width) explaining which of these mechanisms dominate. Pronounced outer bend migration only occurs at tight bends (R*1.5), erosion is focused within the channel axis, where upstream-migrating knickpoints dominate. High centrifugal accelerations at tight bends promote super-elevation of flows on the outer channel flank, thus, enhancing outer bend erosion. At R*>1.5, flow is focused within the channel axis, promoting knickpoints that migrate upstream at an order of magnitude faster than the rate of outer bend erosion at tight bends. Despite the dominance of knickpoints in eroding the channel axis, their stratigraphic preservation is very low. In contrast, the lateral migration of channel bends results in much higher preservation via lateral accretion of deposits on the inner bend. We conclude that multiple mechanisms can control evolution at different channel reaches and that the role of knickpoints has been underestimated from past studies that focused on deposits due to their low preservation potential
Quantifying the three‐dimensional stratigraphic expression of cyclic steps by integrating seafloor and deep‐water outcrop observations
No full textDeep-water deposits are important archives of Earth’s history including the occurrence of powerful flow events and the transfer of large volumes of terrestrial detritus into the world’s oceans. However the interpretation of depositional processes and palaeoflow conditions from the deep-water sedimentary record has been limited due to a lack of direct observations from modern depositional systems. Recent seafloor studies have resulted in novel findings, including the presence of upslope-migrating bedforms such as cyclic steps formed by supercritical turbidity currents that produce distinct depositional signatures. This study builds on process to product relationships for cyclic steps using modern and ancient datasets by providing sedimentological and quantitative, three-dimensional architectural analyses of their deposits, which are required for recognition and palaeoflow interpretations of sedimentary structures in the rock record. Repeat-bathymetric surveys from two modern environments (Squamish prodelta, Canada, and Monterey Canyon, USA) were used to examine the stratigraphic evolution connected with relatively small-scale (average 40 to 55 m wavelengths and 1.5 to 3.0 m wave heights) upslope-migrating bedforms interpreted to be cyclic steps within submarine channels and lobes. These results are integrated to interpret a succession of Late Cretaceous Nanaimo Group deep-water slope deposits exposed on Gabriola Island, Canada. Similar deposit dimensions, facies and architecture are observed in all datasets, which span different turbidite-dominated settings (prodelta, upper submarine canyon and deep-water slope) and timescales (days, years or thousands of years). Bedform deposits are typically tens of metres long/wide, <1 m thick and make up successions of low-angle, backstepping trough-shaped lenses composed of massive sands/sandstones. These results support process-based relationships for these deposits, associated with similar cyclic step bedforms formed by turbidity currents with dense basal layers under low-aggradation conditions. Modern to ancient comparisons reveal the stratigraphic expression of globally prevalent, small-scale, sandy upslope-migrating bedforms on the seafloor, which can be applied to enhance palaeoenvironmental interpretations and understand long-term preservation from ancient deep-water deposits.</p
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
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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