1,721,011 research outputs found
Multi-Proxy Investigations into Mediterranean Outflow Water Variability and Sedimentary Processes on the West Iberian Margin Through the Late Pleistocene
No full textMediterranean Outflow Water (MOW) adds salt and density to open ocean intermediate waters and is therefore an important motor of Atlantic meridional overturning circulation (AMOC) and climate variability. However, the variability in strength and depth of MOW on geological timescales is poorly documented. West Iberian Margin sediments provide important reference records in palaeoceanographic studies, climate events in the marine realm recorded here can be correlated to both the Antarctic and Greenland ice cores as well as to European terrestrial records. These sediments, therefore, provide an opportunity to document MOW variability in high-resolution, underpinned by strong age control.Here, I present new detailed records, with excellent age control, of MOW variability from ~416 ka to present from rapidly accumulated marine sediments recovered from the West Iberian Margin during Integrated Ocean Drilling Program (IODP) Expedition 339. The records of X‐ray fluorescence (XRF), physical grain size, and paleocurrent information from the anisotropy of magnetic susceptibility (AMS) indicate (i) a close relationship between the orientation of principle AMS axes and glacial‐interglacial cycles and (ii) two distinct regimes of MOW behaviour over the last ~416 kyr in grain‐size and AMS variability at orbital (mainly precession) and suborbital timescales. It is inferred that late Pleistocene variability in MOW strength and depth were strongly climate influenced and that changes in circum‐Mediterranean rainfall climate were likely a primary control.A suite of environmental and rock magnetic records from IODP Site U1391 sediments are presented. Different forms of magnetite with varying grain size are inferred as being the dominant magnetic phase in the sediments. From ~130 ka to present, the grain size and concentration of magnetite were strongly controlled by northern high latitude variability. During some stadials in this interval an additional high coercivity component is present, possibly representing haematite derived from North African dust. In sediments older than ~130 ka, evidence of reductive diagenesis is seen across environmental and rock magnetic proxies, and is particularly strong in sediments deposited during marine isotope stages (MIS) 9 and 11. These conditions likely result from a combination of increased productivity and changes in sedimentation rates, associated with vertical migration of the Mediterranean outflow water.XRF (i.e., ln(Zr/Rb)) and magnetic grain size (i.e., ARM/) proxy records from IODP Site U1391 sediments are identified as best representing different physical size fractions of sediment, 33 – 43 m and 8 – 19 m (and likely sizes below 5 m), respectively. Utilising the high-resolution grain size records as proxy of MOW strength in combination with strong chronology; frequency and phasing analysis uncover the relative importance of different climate forcings on MOW. Evidence suggests that spring insolation forcing of MOW strength variability at Site U1391 between ~370 and 60 ka, likely linked with intensification of late-winter North Atlantic storm track activity at precession minima. There is also evidence that this mechanism is impacted upon by the interference of meltwater pulses with North Atlantic circulation
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
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
Making an Argument in the Arts: Using Genre Analysis to Inform Embedded Academic Writing Support in a UK Arts University
Get PDFStudents entering art and design courses in UK higher education come from a range of educational and cultural backgrounds. These students frequently report finding academic writing challenging. Expectations as to the nature of description, analysis and criticality can also differ across subject areas. As a result, students need support in developing their ability to communicate appropriately within their disciplines – their academic literacies. This study applies genre analysis to identify ways in which students express critical thinking in undergraduate Visual Effects Design and Production essays. The findings highlight common ways of linking ideas through exemplification, drawing conclusions from grounds, and challenging the validity of assumptions. Ways of expressing the strength of claims and indicating the writer’s attitude are also frequently used in the sample. The findings are then integrated into a practical model for impromptu teaching of writing by subject lecturers. The article confirms understandings of the way students express criticality in essays, and aligns insights from genre analysis and academic literacies in a novel way. The outcome is a proposal for a practical, low-preparation approach to teaching academic writing within the disciplines
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
Climate-induced variability in Mediterranean outflow to the North Atlantic Ocean during the late Pleistocene
No full textMediterranean Outflow Water (MOW) adds salt and density to open ocean intermediate waters and is therefore an important motor of Atlantic meridional overturning circulation (AMOC) and climate variability. However, the variability in strength and depth of MOW on geological timescales is poorly documented. Here we present new detailed records, with excellent age control, of MOW variability from 416 ka to present from rapidly accumulated marine sediments recovered from the West Iberian Margin during Integrated Ocean Drilling Program (IODP) Expedition 339. Our records of x-ray fluorescence (XRF), physical grain size and palaeocurrent information from the anisotropy of magnetic susceptibility (AMS) indicate (i) a close relationship between the orientation of principle AMS axes and glacial-interglacial cycles and (ii) two distinct regimes of MOW behaviour over the last ~416 kyrs in grain size and AMS variability at orbital (mainly precessional) and suborbital timescales. Between marine isotope stages (MIS) 10 and MIS 4, MOW was focused at a generally shallow depth on the West Iberian Margin, and changes in MOW strength were strongly paced by precession. A transition interval occurred during MIS 5 and 4, when MOW deepened and millennial-scale variability in strength flow strength was superimposed on orbitally paced change. During MIS 11 and from MIS 3 to present, MOW was deeply focused and millennial-scale variability dominated. We infer that late Pleistocene variability in MOW strength and depth were strongly climate- influenced and that changes in circum-Mediterranean rainfall climate were likely a primary control
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