1,720,980 research outputs found
Población y economía en los Andes: las crisis de subsistencia en Talina entre los siglos XVII y XX
Full text linkEl análisis de lo ocurrido en Talina en la larga duración nos permitió avanzar en la construcción de un "mapa" regional que destaca algunas heterogeneidades ya sugeridas en los trabajos mencionados. Nos permitió, también, ubicar al siglo XIX en un contexto cronológico de larga duración con indicadores semejantes como para poder comparar. En particular en el análisis nos detuvimos en las variaciones del clima y en el impacto que tienen las crisis locales en la población.Fil: Gil Montero, Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Estudios Sociales. Universidad Nacional de Tucumán. Instituto Superior de Estudios Sociales; ArgentinaFil: Morales, Mariano Santos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Villalba, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin
Lake fluctuations, plant productivity, and long term variability in high elevation tropical andean ecosystems
Full text linkDespite the large scientific and conservation value of tropical very high elevation Andean ecosystems (above 4500 masl) little is known about environmental trends and ranges of variability. We combined satellite image analyses and dendrochronological methods to quantify changes in water balance and plant productivity of these ecosystems in northern Argentina and southern Bolivia through assessments of lake level fluctuation combined with instrumental climatic records at lower elevation; and to assess the relationships between water balance and two indices of plant productivity: tree ring width of the treelet Polylepis tarapacana and seasonal patterns of vegetation "greenness" (EVI) derived from satellite images. Between 1986 and 2007, inter-annual lake fluctuations were positively correlated with regional precipitation and de Martonne?s aridity index between, showing a decreasing trend during the period. Changes in lake size were correlated with radial growth of P. tarapacana, and with MODIS-derived annual EVI between 2001-2010; thus indicating that water balance has a significant effect on ecosystem functioning. A long term tree ring chronology indicated that recent trends of decreasing plant productivity and lakes size are still within the range of variability of the past 400 years, but such ranges may be exceeded in the coming decades if the trend persists.Fil: Carilla, Julieta. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Grau, Hector Ricardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Paolini, Leonardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Morales, Mariano Santos. Consejo Nacional de Investigaciones Científicas y Técnicas. Científico Tecnológico Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin
First dendroarchaeological dates of prehistoric contexts in South America: chullpas in the Central Andes
Full text linkDespite the existence of long-lived tree species with excellent tree-ring characteristics, the use of dendrochronological techniques for dating archaeological contexts has been very limited in South America. Recent research in the Bolivian Altiplano of the Central Andes has yielded a network of Polylepis tarapacana chronologies that goes back to the 13th century. This species was regularly used by local populations since pre-Columbian times as raw material for beams, lintels, hooks and other architectural features in houses, storage chambers, and sepulchers. The aim of this study is to argue in favor of the potential of P. tarapacana for providing high resolution dates of significant archaeological events during the pre-Columbian era. The chronology of chullpas (burial towers and storage chambers) in the southern Andean Altiplano is used as a case study. Growth rings from P. tarapacana have provided several centennial-length dendrochronological records including a reference regional chronology covering the last 786 years in the Central Andean highlands. Based on this long reference chronology calendar years were assigned to woody pieces from pre-Hispanic chullpas. Dendroarchaeological results are consistent with contextual evidence and most radiocarbon dates from woody samples and related archaeological items. Our results indicate that P. tarapacana has a high potential for providing annually-resolved tree-ring rates for archaeological contexts in the Altiplano since the early 13th century.Fil: Morales, Mariano Santos. Consejo Nacional de Investigaciones Científicas y Técnicas. Científico Tecnológico Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Nielsen, Axel Emil. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; ArgentinaFil: Villalba, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Científico Tecnológico Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; 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
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
Rainfall-controlled tree growth in high-elevation subtropical treelines
Full text linkIt is generally assumed that tree growth in the upper limit of a forest is mainly controlled by summer temperature. This general statement is mostly based on studies from extra-tropical mountains and has been rarely evaluated in subtropical latitudes frequently characterized by drier climates. In the subtropical mountains from Northwestern Argentina (;238 S), annual precipitation decreases with elevation from .1500 mm at 1200? 1500 m, to ,200 mm above 4000 m. In consequence, tree growth at high elevations in the region may be seriously limited by water supply. In order to assess the influence of precipitation on tree growth, we evaluated the relationships between climatic variations and radial growth in four species growing at different altitudinal zones: Juglans australis from the montane cloud forest at 1800 m; Alnus acuminata from the montane savanna-like woodland at 2700 m; Prosopis ferox from the subalpine dryland at 3500 m; and Polylepis tarapacana from the high-elevation alpine dryland at 4750 m. Dendrochronological techniques were used to relate variations in annual ring width with instrumental climatic records. Growth rings were correctly dated to the year of formation, and the cross-dated series standardized using autoregressive models to reduce non-climatic signals present in the records. Tree-ring chronologies, ranging from 117 to 341 years, were compared, during thecommon period, with instrumental climatic records using correlation-function analysis. In spite of the remarkable differences in elevation and environmental conditions among the sampling sites, correlation functions with climate indicated that the radial growth of the four species is largely controlled by precipitation. In most cases, increased precipitation during the previous and current growing seasons favors tree growth, while temperatures are negatively correlated with radial growth, likely due to the negative effect on water availability. These results indicate that the generalized idea of upper-treeline growth limited by summer temperatures should be carefully evaluated in low-latitude environments and does not apply to subtropical areas with severe water deficits or strong moisture seasonalities.Fil: Morales, Mariano Santos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Villalba, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Grau, Hector Ricardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Investigaciones Ecológicas de las Yungas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Paolini, Leonardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Investigaciones Ecológicas de las Yungas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin
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