1,720,973 research outputs found
Efectividad de distintos pretratamientos en el análisis granulométrico de tres suelos contrastantes de la Región Pampeana = Effectiveness of different pretreatments on granulometry analysis for three contrasting soils of the Pampean Region
No full textLa granulometría es una de las características fundamentales del suelo, y su evaluación brinda información clave en la determinación
de sus propiedades físicas. Sin embargo, existen divergencias metodológicas en los procedimientos de dispersión del suelo y de eliminación de la materia orgánica (EMO). En este trabajo se evaluó la variación de la granulometría en tres suelos pampeanos diferenciados en su textura, mineralogía y contenido de MO. Se pusieron a prueba dos procedimientos de EMO (calcinación a 430 ºC y oxidación por H2O2) y dos velocidades de agitación (90 y 150 rpm) en agitador recíproco. Cuando la materia orgánica fue eliminada con agua oxigenada se obtuvo una mayor extracción de arcilla, independientemente de la velocidad de agitación. Sin embargo, en promedio, se encontraron contenidos más altos de arcillas con una mayor velocidad de agitación. En el suelo arenoso (Haplustol), la combinación calcinación y agitación 150 rpm presentó un desempeño estadísticamente similar al H2O2 y agitación 150 o 90 rpm. Por el contrario, para los suelos de textura fina evaluados en este trabajo (Argiudol y Hapludert) la utilización de la calcinación no sería conveniente ya que subestima el contenido de arcilla debido a una posible reorganización de las partículas de arcilla producida por el calor. Este trabajo destaca la importancia de las condiciones metodológicas en los resultados de la distribución granulométrica de los suelos, mientras que la evaluación de un mayor número de suelos y la evaluación de otros Ordenes es necesaria para lograr procedimientos adecuados para dicha determinación.Granulometry is one of the main soil characteristics and its evaluation gives key information in the determination of its physical
properties. However, there are still methodological discrepancies related to soil dispersion and organic matter elimination (OME)
procedures. In this work changes in granulometry were assessed for in three soils with contrasting textures, mineralogy, and
organic matter levels. Two OME procedures (calcination at 430 ºC and oxidation by H2O2) and two shaking velocities (90 and
150 rpm) in reciprocal agitator were evaluated. When organic matter was eliminated with H2O2, higher clay extraction was
obtained regardless of the agitation velocities. In the sandy soil (Haplustoll), the combination of calcination and 150 rpm shaking
velocity showed a similar statistical performance than H2O2 and 150 or 90 rpm shaking treatment. On the contrary, for the
fine texture soils assessed for in this work (Argiudoll and Hapludert), calcination techniques would not be appropriate as they
underestimated clay content due to a probable clay particle reorganization produced by heat. This work highlights the importance
of methodological conditions on the outcome of soil granulometric distribution. The evaluation of a larger number of soils
and of other soil Orders is necessary to achieve sound determination methodologies.Instituto de SuelosFil: Kraemer, Filipe Behrends. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Manejo y Conservación de Suelos; ArgentinaFil: Fernández, Patricia Lilia. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Manejo y Conservación de Suelos; ArgentinaFil: Ceddia, Marcos Bacis. Universidade Federal Rural de Rio de Janeiro. Departamento de Solos; BrasilFil: Chagas, Celio Ignácio. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Manejo y Conservación de Suelos; ArgentinaFil: Morras, Hector. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; Argentin
Effectiveness of different pretreatments on granulometry analysis for three contrasting soils of the Pampean Region
Get PDFLa granulometría es una de las características fundamentales del suelo, y su evaluación brinda información clave en la determinación de sus propiedades físicas. Sin embargo, existen divergencias metodológicas en los procedimientos de dispersión del suelo y de eliminación de la materia orgánica (EMO). En este trabajo se evaluó la variación de la granulometría en tres suelos pampeanos diferenciados en su textura, mineralogía y contenido de MO. Se pusieron a prueba dos procedimientos de EMO (calcinación a 430 ºC y oxidación por H2O2) y dos velocidades de agitación (90 y 150 rpm) en agitador recíproco. Cuando la materia orgánica fue eliminada con agua oxigenada se obtuvo una mayor extracción de arcilla, independientemente de la velocidad de agitación. Sin embargo, en promedio, se encontraron contenidos más altos de arcillas con una mayor velocidad de ag tación. En el suelo arenoso (Haplustol), la combinación calcinación y agitación 150 rpm presentó un desempeño estadísticamente similar al H2O2 y agitación 150 o 90 rpm. Por el contrario, para los suelos de textura fina evaluados en este trabajo (Argiudol y Hapludert) la utilización de la calcinación no sería conveniente ya que subestima el contenido de arcilla debido a una posible reorganización de las partículas de arcilla producida por el calor. Este trabajo destaca la importancia de las condiciones metodológicas en los resultados de la distribución granulométrica de los suelos, mientras que la evaluación de un mayor número de suelos y la evaluación de otros Ordenes es necesaria para lograr procedimientos adecuados para dicha determinación.Granulometry is one of the main soil characteristics and its evaluation gives key information in the determination of its physical properties. However, there are still methodological discrepancies related to soil dispersion and organic matter elimination (OME) procedures. In this work changes in granulometry were assessed for in three soils with contrasting textures, mineralogy, and organic matter levels. Two OME procedures (calcination at 430 ºC and oxidation by H2O2) and two shaking velocities (90 and 150 rpm) in reciprocal agitator were evaluated. When organic matter was eliminated with H2O2, higher clay extraction was obtained regardless of the agitation velocities. In the sandy soil (Haplustoll), the combination of calcination and 150 rpm shaking velocity showed a similar statistical performance than H2O2 and 150 or 90 rpm shaking treatment. On the contrary, for the fine texture soils assessed for in this work (Argiudoll and Hapludert), calcination techniques would not be appropriate as they underestimated clay content due to a probable clay particle reorganization produced by heat. This work highlights the importance of methodological conditions on the outcome of soil granulometric distribution. The evaluation of a larger number of soils and of other soil Orders is necessary to achieve sound determination methodologies.Fil: Behrends Kraemer, Filipe. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernández, Patricia Lilia. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ceddia, Marcos Bacis. Universidade Federal Rural de Rio de Janeir; BrasilFil: Chagas, Celio Ignacio. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Morrás, Héctor José María. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; Argentin
Acurácia e incerteza em abordagens de mapeamento digital de solos para extrair e transferir informações pedológicas a partir de área de referencia
No full textContradicting the need for detailed maps, we currently experience scarcity of investments on soil surveys in Brazil. In this sense, it is necessary to resort to techniques that allow the expansion of the mapped areas, at relatively lower costs. From this perspective, this work focused on the investigation of procedures and tools for the retrieving and extrapolation of soil type information from a reference area to its surroundings. The objectives included: (i) retrieving information from a detailed soil map of a reference area; (ii) to evaluate the transferability of information to a larger area, which preserves similar environmental characteristics similar to those of the pilot area; (iii) evaluate the accuracy and uncertainty of the inference models. From a Digital Elevation Model, a series of topographic indexes were calculated, which were correlated with the soil classes, represented by mapping units of the legacy map. The objective was to infer from the soil-landscape relationship of the pilot area, the distribution of soil types in the extrapolation area. For that duty, three inference procedures were applied, one data-driven (Random Forest (RF)) and two others, based on knowledge (Rule-based reasoning and Case-based reasoning - ArcSIE). Regarding RF, 52 models were graded from a routine of tuning and different combinations of training data. Although considered a robust predictor, RF demonstrated sensitivity to training strategies. Most of the models presented low accuracy. However, at least one model with more than 80% of global accuracy was obtained. Regarding RBR and CBR procedures, only the former resulted in a map with good precision. The advantage of using knowledge-based systems like RBR is to make explicit the soil-landscape relationship through a systematic set of rules. By accessing the uncertainty of the predictions, in addition to evaluating the behavior of the models, it was possible to observe the complexity of the soil-landscape relationship of Oxisols and Inceptisols, characteristic of tropical environments. This is particularly important for model review and sampling planning in the search for more accurate maps.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Contrapondo a necessidade de mapas mais detalhados, atualmente enfrentamos a escassez de recursos destinados ao levantamento de solos. Neste sentido, é preciso recorrer a técnicas que viabilizem a expansão das áreas mapeadas, a custos relativamente mais baixos. Sob essa perspectiva, este trabalho focou na investigação de procedimentos e ferramentas para a extrapolação de informações sobre classes de solo de uma área de referência para seu entorno. Os objetivos incluíram: (i) recuperar informações de um mapa de solos detalhado de uma área de referência; (ii) avaliar a transferibilidade da informação para uma área 15 vezes maior, que preserva características de paisagem semelhantes às da área piloto; (iii) avaliar a acurácia e a incerteza dos modelos de inferência. A partir de um Modelo Digital de Elevação, calculou-se uma série de índice topográficos, os quais foram correlacionados com as classes de solo, representadas por unidades de mapeamento do mapa legado. O objetivo, portanto, foi inferir, a partir da relação solo-paisagem da área piloto, a distribuição dos tipos de solo na área de extrapolação. Para tanto, foram aplicados três procedimentos de inferência, um baseado em dados (Random Forest (RF)) e outros dois baseados no conhecimento (Rule-based reasoning-RBR e Case-based reasoning-CBR - ArcSIE). Com relação a RF, foram grados 52 modelos a partir de uma rotina de ajustes e diferentes combinações de dados de treinamento. Embora considerado um preditor robusto, a RF demonstrou sensibilidade as estratégias de treinamento. Grande parte dos modelos apresentou baixa precisão, contudo, obteve-se ao menos um modelo com mais de 80% de acurácia global. Em relação aos procedimentos RBR e CBR, apenas o primeiro resultou em um mapa com boa precisão. A vantagem da utilização de sistemas baseados no conhecimento com o RBR é o de tornar explicita a relação solo-paisagem através de um conjunto sistematizado de regras. Ao acessar a incerteza das predições, além de avaliar o comportamento dos modelos, foi possível observar a complexidade da relação solo paisagem, característica de ambientes tropicais. Este aspecto é particularmente importante para revisão de modelos e planejamento de coletas de solo na busca por mapas com maior acurácia
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
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
- …
