1,720,959 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
Late Miocene expansion of grasslands in northwest Argentina linked to shifting hydroclimate: A complex interaction among tectonics, climate, and ecology
No full textFactors driving the late Miocene expansion of C4 grasses remain widely debated. Here, we explored the role of climate and fire in controlling the abundance of C4 vegetation in the Angastaco Basin (Palo Pintado area) and La Viña Basin, NW Argentina, during the late Miocene (ca. 14−5.33 Ma). From paleosol horizons, we reconstructed paleoclimate and paleovegetation conditions using phytolith assemblages, geochemical and isotopic proxies, and polycyclic aromatic hydrocarbons (PAHs) to determine fire input. Our paleoclimate reconstructions suggest a stable mean annual temperature (MAT) of ∼10 °C and a gradual decline in mean annual precipitation (MAP) from 1100 mm yr−1 to 850 mm yr−1. Paleovegetation reconstructions from carbon isotopic composition and phytolith assemblages show a maximum of ∼15% C4 vegetation by 6 Ma. No significant increases in fire occurrence or establishment of fire feedbacks were identified from the PAH data. Though low in abundance (∼3% on average), our data identified the presence of C4 grass by the late Miocene. The lack of significant C4 expansion in this region was likely controlled by the changing hydroclimatic conditions associated with the Andes mountain range—increasing aridity and elevation constraints along with the lack of a fire feedback might have limited the distribution of C4 vegetation.Fil: Azmi, Iffat. North Carolina State University; Estados UnidosFil: Hyland, Ethan. North Carolina State University; Estados UnidosFil: Cotton, Jennifer. California State University Northridge;Fil: Ghosh, Adit. University of Southern California; Estados UnidosFil: Raigemborn, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Tineo, David. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Hauswirth, Scott. California State University Northridge;Fil: Insel, Nadja. Northeastern Illinois University (northeastern Illinois)
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
Neogene Expansion of C4 Grasslands in South America: Interactions Between Climate, Ecology, And Tectonics.
No full textFacies and provenance analysis of the Midcontinent Rift System (MRS) in Kansas
Get PDFMaster of ScienceDepartment of GeologyKarin GoldbergThe Midcontinent Rift System (MRS) formed a half-graben that extends into NE Kansas. The Precambrian rift succession, penetrated by Texaco Noel Poersch#1 (NP#1) well in Washington Co. at depths between 2846 and 11300 ft, comprises two successions. The lower one (11300-7429 ft) is dominated by clastic sediments and the upper one (7429-2846 ft) mainly by volcanic rocks, which suggests a radical change during rift evolution. This study is aimed at describing the sedimentary succession within the rift in Kansas, relating variations in sedimentary facies to the different stages of rift development. Detailed facies and provenance analyses were carried out in discontinuous cores retrieved from the lower and upper successions (5395-11300 ft deep). Sixteen lithofacies were identified, grouped into six different facies associations (fluvial, eolian, mudflat/lake margin, lacustrine, alluvial fan, and fan delta). Overall, the studied succession comprises continental deposits laid down dominantly in alluvial and eolian settings, with the intermittent development of lacustrine systems. Three rift sequences, bound by flooding surfaces and controlled by tectonic pulses in rift basin, were identified. Superimposed on the tectonic phases, changing climate conditions resulted in recurrent dry and wet cycles. Provenance analysis showed a higher contribution of infracrustal rocks in the source areas. Minor shifts in provenance could be due to re-arrangements of faulted block and variable proportion of axial vs. transversal input into the rift basin. Despite the tectono-stratigraphic framework typical of a syn-rift succession, based on the available geochronological and compositional data, the rift succession in KS seems to be more compatible with post-rift successions elsewhere
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