1,720,989 research outputs found
Last millennial environmental reconstruction based on a multi-proxy record from Laguna Nassau, Western Pampas, Argentina
Get PDFWe present a multi-proxy record from Laguna Nassau (LN), a shallow lake which developed in a blowout depression in the semi-arid sandy lowlands of the Western Pampas of Argentina. This multi-proxy stacked record reveals the evolution of an incipient water body subjected to warm and dry conditions from ~900 to 770 cal yr BP, an interval that is coeval with the Medieval Climatic Anomaly (MCA) period. Vegetation was dominated locally by Typha, and regionally by the Espinal, represented by Celtis, along with psammophytic-halophytic communities in sand dunes and lowlands. After that, variable water-depths and unstable conditions occurred in the water body in relation to dry and humid climatic phases until ~200 cal yr BP, likely related to a transition from warm and dry conditions, corresponding to the MCA, to a colder and wet climatic setting during a period concurrent with the Little Ice Age (LIA). This water body evolved into a shallow lake since then, with a more stable and higher water level, and regional vegetation characterized by the Espinal and psammophytic-halophytic communities mantling and stabilizing the nearby sand dunes. This evolution suggests complex hydrological responses of LN likely associated with its sensitivity to climatic variability. Our results highlight important contrasts in hydrologic balance during the MCA and LIA along the western and northeastern Pampas, suggesting important shifts mainly in the South-American Summer Monsoon at centennial timescales over the last millennium.Fil: Vilanova, Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Schittek, Karsten. Universitat zu Köln; AlemaniaFil: Geilenkirchen, Mathias. Universitat zu Köln; AlemaniaFil: Schäbitz, Frank. Universitat zu Köln; AlemaniaFil: Schulz, Wilfried. Universitat zu Köln; Alemani
Contributions to the pollen flora of high-andean cushion peatlands, jujuy province, northwestern Argentina
Get PDFSe presenta la caracterización polínica de 15 especies, nuevas para la palinoflora andina, distribuidas en 12 familias, con una clave para su identificación. Las mismas pertenecen a la flora actual de comunidades vegetales de turberas altoandinas. Estos estudios tienen como objetivo aportar al conocimiento polínico de los ambientes de turberas altoandinas, con el fin de optimizar la identificación de tipos polínicos presentes en los registros fósiles del cuaternario de la región del noroeste argentino (NOA). Las descripciones pertenecen a las siguientes especies: Apiaceae: Lilaeopsis macloviana, Asteraceae: Cuatrecasasiella argentina, Perezia pygmaea, Brassicaceae: Eudema friesii, Cyperaceae: Carex gayana, Zameioscirpus muticus, Fabaceae: Astragalus micranthellus, Gentianaceae: Gentianella meyeniana, Juncaceae: Distichia muscoides, Orobanchaceae: Bartsia crenoloba, Castilleja pumila, Plantaginaceae: Plantago tubulosa, Poaceae:xPuccinellia frigida, Portulacaceae: Calandrinia compacta, Ranunculaceae: Halerpestes exilis.The descriptions of15 pollen types, new for the high-Andean pollen flora, distributed in 12 families, are presented, with a key for their identification. They belong to the current flora of cushion peatlands' plants communities. The aim of these studies is to contribute to the knowledge of pollen of high Andean peatland ecosystems, in order to optimize the identification of pollen types conserved in quaternary fossil records in Northwestern Argentina (NOA). The following species are described: Apiaceae: Lilaeopsis macloviana, Asteraceae: Cuatrecasasiella argentina, Pereziapygmaea, Brassicaceae: Eudema friesii, Cyperaceae: Carex gayana, Zameioscirpus muticus, Fabaceae: Astragalus micranthellus, Gentianaceae: Gentianella meyeniana, Juncaceae: Distichia muscoides, Orobanchaceae: Bartsia crenoloba, Castilleja pumila, Plantaginaceae: Plantago tubulosa, Poaceae: Puccinellia frigida, Portulacaceae: Calandrinia compacta, Ranunculaceae: Halerpestes exilis.Fil: Torres, Gonzalo Román. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Lupo, Liliana Concepcion. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Sánchez, Ana Carina. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Cátedra de Botánica Sistemática y Fitogeografía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Schittek, Karsten. Universität Heidelberg; Alemani
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
Radiocarbon ages, calibrated radiocarbon ages and modelled ages of the composite profile from core Tuz-694
No full textkoamabayili/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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