1,721,004 research outputs found
Globalization, migration, and Latin American ecosystems
Get PDFIncreasing rural emigration in Latin America, promoted by globalization-related socioeconomic changes, is favoring the abandonment of areas which are marginal for agriculture. The process, most important in areas of steep slope and subhumid conditions, favors the recovery of natural ecosytems and thus of biodiversity and environmental services.Fil: Aide, T. Mitchell. Universidad de Puerto Rico; Puerto RicoFil: 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; Argentin
Migración rural-urbana y sus implicancias para los patrones de uso de la tierra y la biodiversidad de la provincia de Misiones.
Get PDFTesis (Grado Doctor en Ciencias Biológicas)- Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales.
Lugar de Trabajo: Laboratorio de Investigaciones de las Yungas. Universidad Nacional de Tucumán. 2010
121 h. + Anexo Digital con Sonogramas de las especies de aves de la Provincia de Misiones. Contiene Referencia Bibliográfica. Abstract en español e inglés.La migración rural-urbana es un creciente proceso demográfico que modifica los patrones de uso y cobertura de la tierra. En las últimas décadas de este siglo, la población rural ha tendido a disminuir en muchos países alrededor del mundo. Este patrón demográfico conlleva a una transformación de los patrones de uso de la tierra los cuales representan el principal factor causante de la pérdida de biodiversidad en el planeta. En este estudio, yo analizo los cambios socioeconómicos y de los patrones de uso del suelo durante los últimos 30 años, comparo riqueza y abundancia relativa de grupos de especies con diversas características ecológicas como indicadores de las implicancias de los cambios de uso del suelo asociados a la migración rural-urbana. Los resultados demuestran que Misiones esta en una fase temprana de la transición demográfica y los cambios principales en el uso del suelo entre 1973 y 2006 han sido una pérdida de 5503 km2 de bosques naturales y un aumento de 2865km2 de plantaciones monoespecíficas (principalmente Pinus y Eucaliptos). Sin embargo, entre 1970 y 2001, el cambio de la población rural fue el con ductor de la deforestación en la provincia (r2=0.82; p p<0.005).Estos cambios han tenido diferentes efectos para la biodiversidad. El habitat fue determinante de la comunidad de hormigas y de aves,mientras que la matriz fue el mejor predictor de comunidad de aves.Misiones posee el remanente continuo más grande del Bosque Atlántico,el cual se caracteriza por su de alto nivel de de la biodiversidad y de endemismos;pero este bosque esta siendo transformado principalmente a plantaciones monoespecíficas. Aunque los cambios demográficos en Misiones hayan sido similares a otras regiones (es decir migración rural-urbana) y el aumento en plantaciones forestales ayuda a mantener la cubierta del bosque, esta cubierta tiene valor ecológico más bajo que el bosque nativo. Para asegurar la conservación de la alta biodiversidad del Bosque Atlántico en Misiones se necesita un mejor esfuerzo en entender las interacciones entre los factores diversos que afectan a patrones de uso del suelo en Misiones
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
Land Change in the Greater Antilles between 2001 and 2010
Get PDFLand change in the Greater Antilles differs markedly among countries because of varying socioeconomic histories and global influences. We assessed land change between 2001 and 2010 in municipalities (second administrative units) of Cuba, Dominican Republic, Haiti, Jamaica, and Puerto Rico. Our analysis used annual land-use/land-cover maps derived from MODIS satellite imagery to model linear change in woody vegetation, mixed-woody/plantations and agriculture/herbaceous vegetation. Using this approach, we focused on municipalities with significant change (p ≤ 0.05). Between 2001 and 2010, the Greater Antilles gained 801 km2 of woody vegetation. This increase was mainly due to the return of woody vegetation in Cuba, and smaller increases in Puerto Rico and the Dominican Republic. Despite relatively similar environments, the factors associated with these changes varied greatly between countries. In Puerto Rico, Dominican Republic, and Jamaica, agriculture declined while mixed-woody vegetation increased, mostly in montane regions. In contrast, Cuba experienced an extensive decline in sugarcane plantations, which resulted in the spread of an invasive woody shrub species and the increase in woody vegetation in areas of high agricultural value. In Haiti, the growing population, fuelwood consumption, and increase in agriculture contributed to woody vegetation loss; however, woody vegetation loss was accompanied with a significant increase in the mixed woody and plantations class. Most regional analyses often treated the Greater Antilles as a homogeneous unit; our results suggest that historical and socio-economic differences among countries are crucial for understanding the variation in present day land change dynamics.Fil: Alvarez Berrios, Nora L.. Universidad de Puerto Rico; Puerto RicoFil: Redo, Daniel J.. Universidad de Puerto Rico; Puerto RicoFil: Aide, T. Mitchell. Universidad de Puerto Rico; Puerto RicoFil: Clark, Matthew L.. Sonoma State University; Estados UnidosFil: Grau, Hector Ricardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Asymmetric forest transition driven by the interaction of socioeconomic development and environmental heterogeneity in Central America
Get PDFForest transitions (FT) have been observed in many developed countries and more recently in the developing world. However, our knowledge of FT from tropical regions is mostly derived from case studies from within a particular country, making it difficult to generalize findings across larger regions. Here we overcome these difficulties by conducting a recent (2001-2010) satellite-based analysis of trends in forest cover across Central America, stratified by biomes, which we related to socioeconomic variables associated with human development. Results show a net decrease of woody vegetation resulting from 12,201 km2 of deforestation of moist forests and 6,825 km2 of regrowth of conifer and dry forests. The Human Development Index was the socioeconomic variable best associated with forest cover change. The least-developed countries, Nicaragua and Guatemala, experienced both rapid deforestation of moist forests and significant recovery of conifer and dry forests. In contrast, the most developed countries, Panama and Costa Rica, had net woody vegetation gain and amore stable forest cover configuration. These results imply a good agreement with FT predictions of forest change in relation to socioeconomic development, but strong asymmetry in rates and directions of change largely dependent upon the biomewhere change is occurring. The FT model should be refined by incorporating ecological and socioeconomic heterogeneity, particularly inmulticountry and regional studies. These asymmetric patterns of forest change should be evaluatedwhen developing strategies for conserving biodiversity and environmental services.Fil: Redo, Daniel J.. Universidad de Puerto Rico; Puerto RicoFil: Grau, Hector Ricardo. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aide, T. Mitchell. Universidad de Puerto Rico; Puerto RicoFil: Clark, Matthew L.. Sonoma State University; Estados Unido
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
Implications of rural-urban migration for conservation of the atlantic forest and Urban growth in Misiones, Argentina (1970-2030)
Get PDFAbstract Global trends of increasing rural-urban migration and population urbanization could provide opportunities for nature conservation, particularly in regions where deforestation is driven by subsistence agriculture. We analyzed the role of rural population as a driver of deforestation and its contribution to urban population growth from 1970 to the present in the Atlantic Forest of Argentina, a global conservation priority. We created future land-use-cover scenarios based on human demographic parameters and the relationship between rural population and land-cover change between 1970 and 2006. In 2006, native forest covered 50% of the province, but by 2030 all scenarios predicted a decrease that ranged from 18 to 39% forest cover. Between 1970 and 2001, rural migrants represented 20% of urban population growth and are expected to represent less than 10% by 2030. This modeling approach shows how rural-urban migration and land-use planning can favor nature conservation with little impact on urban areas.Fil: Izquierdo, Andrea Elisa. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina. Centro de Investigaciones del Bosque Atlántico; ArgentinaFil: Grau, Hector Ricardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Aide, T. Mitchell. Universidad de Puerto Rico; Puerto Ric
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
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