1,720,982 research outputs found
A new soil-landscape approach to the genesis and distribution of typic and vertic Argiudolls in the Rolling Pampa of Argentina
No full textThe Rolling Pampa is one of the several subregions of the large Pampa plains in central Argentina. The most extensive and representative soils in the area are Typic Argiudolls, together with a smaller proportion of Vertic Argiudolls occurring mainly on relief tops and upper slope facets in a strip close to the Paraná – Río de la Plata fluvial axis. According to the traditional interpretation, the vertic soil properties are due to a combination of finer parent materials resulting from granulometric selection during eolian transport from the south-western Andean sources and intense smectite formation in a more humid eastern sector of the Pampa. A new sedimentological and geopedologic approach explains more accurately the development and spatial distribution of the main soils in the subregion. According to this, smectitic sediments coming from northern sources in the Paraná basin were deposited in the Rolling Pampa and later covered by illitic loess sediments from south-western Andean sources. In a subsequent humid period in the Holocene, the illitic sediments were eroded and the smectitic sediments were exposed on the upper parts of the undulating relief. As a consequence, Typic Argiudolls developed on the illitic and volcanoclastic Andean sediments, while vertic soils evolved in higher positions of the landscape on the smectitic sediments of older age and different origin.Inst.de SuelosFil: Morras, Hector. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; ArgentinaFil: Moretti, Lucas Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; Argentin
Genesis of subtropical soils with stony horizons in NE Argentina: Autochthony and polygenesis
No full textDeep red soils, combining characteristics of highly weathered materials together with a significant degree of clay illuviation and with stony horizons close to the saprolite, are found in the Province of Misiones, northeastern Argentina. Two basic types of stony horizons have been found, which with the fine-grained material above are together considered autochthonous. The first one is a “ferruginous nodular horizon”, composed mainly of in situ goethitic nodules of gravel size resulting from weathering and glaebulization processes of basalt. The second are “siliceous horizons” which are also in situ, derived from pre-existing quartz veins within the basalt. In contrast, different analytical evidences, particularly the vertical and geographical variations in the SOM-stable carbon isotope ratios and the mineralogical composition of fine and coarse fractions, suggest that these red subtropical soils are polygenetic, being the result of a two-fold process linked to paleoecological fluctuations. In the framework of these results, different interpretations about the origin of these soils and their parent materials, and particularly the “tropical loess” theory, are discussed.Instituto de SuelosFil: Morras, Hector. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; ArgentinaFil: Moretti, Lucas Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; ArgentinaFil: Piccolo, Gabriel Agustin. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cerro Azul; ArgentinaFil: Zech, Wolfgang H. University of Bayreuth. Institute of Soil Science and Soil Geography; Alemani
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
Mineralogía de la fracción arena de los suelos y sedimentos superficiales de la Región Pampeana. Una revisión.
Full text linkSe efectuó una revisión de la literatura existente sobre la composición mineralógica de la fracción arena de suelos y sedimentos superficiales de la región pampeana. Se seleccionaron diversos componentes de las fracciones livianas (vidrio volcánico, cuarzo, feldespatos potásicos, plagioclasas y litoclastos) y pesada (piroxenos, anfíboles y micas). Esta información fue comparada con estudios recientes sobre la composición mineralógica de la fracción arena de suelos de la Pampa Ondulada y sectores vecinos, en los que se evidenció una importante heterogeneidad mineralógica y una variación composicional de sur a norte de esta sub-región. En función de los datos de la literatura pudo establecerse un claro contraste entre la composición de la fracción arena de distintos sectores de la región pampeana, permitiendo establecer una delimitación entre la Región Mineralógica (R.M.) sur, la R.M. central. la R.M. norte y la R.M. oriental. Los datos evaluados evidencian que los sedimentos loéssicos pampeanos son claramente heterogéneos y sus diferencias composicionales estarían relacionadas con contribuciones variadas en tiempo y en espacio de muy diversas fuentes proximales y distales de rocas ígneas, metamórficas y sedimentarias que rodean la llanura. Además de los aportes eólicos, los resultados sugieren una influencia considerable del transporte fluvial en la conformación de los sedimentos superficiales de esta región.Fil: Morras, Héctor J.M. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; Argentin
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
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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