1,721,195 research outputs found
Postglacial history of the Patagonian forest/steppe ecotone (41–43°S)
Full text linkPatagonian vegetation has dramatically changed in composition and distribution over the last 23,000 years. Although the vegetation history has been inferred from individual pollen records, the regional patterns and drivers of vegetation development are poorly understood. High resolution pollen and charcoal data from eleven sites located along the eastern flanks of the Patagonian Andes (41–43°S) were examined to reconstruct the Lateglacial and Holocene vegetation and fire history of steppe/forest ecotone and separate the relative influence of climatic versus non-climatic factors in shaping the patterns of ecological change. Pollen data indicate that, as the Lateglacial climate became progressively wetter, the initial steppe vegetation was replaced by open forest of Nothofagus in the Lateglacial and early Holocene periods, and by closed forest in the late Holocene. Fire activity was lowest during the Lateglacial/early-Holocene transition and gradually increased through the Holocene. Prior to ca 5000 cal yr BP, the conifer Austrocedrus chilensis possibly persisted in isolated populations along the eastern boundary of its modern distribution. Cooler/more humid conditions after ca 5000 cal yr BP allowed the development of the modern mixed Nothofagus–Austrocedrus forest. The paleoenvironmental record points to the sensitivity of the forest/steppe ecotone in the past, not only to climate but also to complex environmental feedbacks that amplified the effects of climate change.Fil: Iglesias, Virginia. State University of Montana; Estados UnidosFil: Whitlock, Cathy. State University of Montana; Estados UnidosFil: Markgraf, Vera. State University of Colorado Boulder; Estados Unidos. University of Arizona; Estados UnidosFil: Bianchi, Maria Martha. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin
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
A Holocene history of monkey puzzle tree (pehuén) in northernmost Patagonia
No full textAim: Although it is established that climate and fire have greatly influenced the long-term ecosystem dynamics of Patagonia south of 40°S, the environmental history from northernmost Patagonia (37–40°S), where endemic and endangered monkey puzzle tree (Araucaria araucana) occurs, is poorly known. Here we ask: (a) What is the Holocene vegetation and fire history at the north-eastern extent of A. araucana forest? (b) How have climate and humans influenced the past distribution of A. araucana?. Location: Northernmost Patagonia, Argentina and Chile (37–40°S). Taxa: Araucaria araucana, Nothofagus, Poaceae. Methods: Sedimentary pollen and charcoal from Laguna Portezuelo (37.9°S, 71.0°W; 1,730 m; 11,100 BP) were evaluated using statistical methods and compared with other palaeoecological, independent palaeoclimate, and historical records to assess how changes in climate and land use influenced local-to-regional environmental history. Results: An open forest-steppe landscape persisted at L. Portezuelo throughout the Holocene with generally low-to-moderate fire activity. Increased Nothofagus pollen after ~6,590 BP suggests increases in shrubland and moisture in association with cooler conditions and greater seasonality and ENSO activity. Araucaria pollen appeared at L. Portezuelo at ~6,380 BP, but was low in abundance until ~370 BP, when it rose with charcoal levels. This increase in Araucaria and fire coincided with a regional influx of Mapuche American Indians. Nothofagus deforestation and Pinus silviculture marked Euro-American settlement beginning in the 19–20th century. Main conclusions: (a) Rapid postglacial warming and drying limited the distribution of Araucaria in the central valley of Chile. In the middle and late Holocene, decreased temperatures and greater seasonality and ENSO activity increased precipitation variability allowing Araucaria expansion at its north-eastern limit. (b) Greater abundance of Araucaria and heightened fire activity at L. Portezuelo after 370 BP coincided with increased Mapuche-Pehuenche American Indian land use, suggesting that Araucaria may have been managed in a human-altered landscape.Fil: Nanavati, William. State University of Montana; Estados UnidosFil: Whitlock, Cathy. State University of Montana; Estados UnidosFil: Outes, Ana Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; ArgentinaFil: Villarosa, Gustavo. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; Argentin
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
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