1,721,040 research outputs found
Population dynamics and palaeoenvironmental inferences of Turonian planktonic foraminiferal assemblages from SE Tanzania and ODP Site 762 (Exmouth Plateau, eastern Indian Ocean)
No full textThe Tanzania Drilling Program (TDP) recovered hemipelagic sediments from land-based boreholes
that yielded extraordinarily well-preserved, diverse Turonian foraminifera. Reliable oxygen and carbon isotopic
analyses through most of the Turonian Stage and biostratigraphic data were documented. This study compares
Turonian foraminiferal population dynamics and associated geochemical proxy records among the TDP bore-
holes with correlative records from Ocean Drilling Program Site 762 (Exmouth Plateau, eastern Indian Ocean).
The two regions were separated by ∼12° latitude and ∼5000 km of ocean, with the Indian continental plate
located between. Taxonomic turnover is similar and is nearly simultaneous in both regions across the transition
from the Helvetoglobotruncana helvetica Zone to the Falsotruncana maslakovae Zone (∼93.0 Ma). Changes
include overlapping extinctions of all helvetoglobotruncanids, most dicarinellids and one species of Praeglo-
botruncana and subsequent first appearances of marginotruncanid and falsotruncanid species. Increased abun-
dance of biserial planktonic foraminifera is recorded at multiple TDP sites and at Site 762 across the contact of
the Fa. maslakovae and Huberella huberi zones c. 0.5 Myr after the Hv. helvetica/Fa. maslakovae transition.
Geochemical records at the two sites do not indicate associated palaeoenvironmental changes in surface water
conditions that would explain coordinated changes in species composition on opposites sides of the Indian
Ocean
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
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
The resilience of Tethyan planktonic and benthic calcifiers to Early Cretaceous perturbations: comparison between the Valanginian Weissert Event and the early Aptian Oceanic Anoxic Event 1a
No full textDuring the Cretaceous, the Berriasian–Aptian interval witnessed a transition from a relatively cool climate with intermittent polar ice to a greenhouse state that persisted throughout the Late Cretaceous. These palaeoclimatic changes were associated with the construction of large igneous provinces (LIPs), which significantly perturbed the ocean–atmosphere system by introducing large amounts of CO2, trace metals and micronutrients, thereby impacting the biosphere. Our study focused on the Tethyan Ocean during the Early Cretaceous, examining the resilience of planktonic and shallow-water benthic calcifying algae to environmental changes. We observed their adaptation, recovery dynamics and the influence of palaeoCO2 levels on their resilience. Calcification patterns of calcareous nannoplankton served as a proxy for ecological and engineering resilience. While calcareous nannoplankton as a whole showed high resistance, individual taxa exhibited varying levels of resilience. Nannoconids, particularly narrow-canal ones, were highly sensitive and had low resistance. In contrast, Watznaueria barnesiae showed the least sensitivity and highest resistance, likely due to its adaptive strategies and long lifespan. Nannoplankton calcification recovery (engineering resilience) from the Weissert Event took c. 3 million years. After the Early Aptian Oceanic Anoxic Event 1a (OAE1a), instead, nannoplankton did not return to pre-perturbation conditions. In shallow-water platforms, Dasycladales, aragonitic benthic calcifiers, exhibited lower resilience compared to nannofossils. They experienced a decline in species diversity across both the Weissert Event and the OAE 1a, which could indicate higher sensitivity to reduced carbonate saturation under high atmospheric pCO2 conditions. After the Valanginian Weissert Event, Dasycladales were able to recover, albeit they show a much lower engineering resilience compared to nannoconids, as it took nearly 10 million years to revert to pre-disturbance diversity. The OAE 1a represented a more intense perturbation: the decrease of species diversity was much more drastic and permanent, and Dasycladales were unable to recover, losing their dominant role as carbonate platform biocalcifiers for the remainder of the Cretaceous. Our study provides an assessment of the resilience of Tethyan phytoplanktonic and shallow-water benthic calcifying algae to disturbances during the Early Cretaceous, with implications for tipping points associated with palaeoCO2 levels. The differential responses in terms of timing and magnitude and the recovery dynamics contribute to the understanding of the potential impacts of current and future global changes on the resilience of marine ecosystems and the thresholds that may lead to ecological crises
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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