1,720,956 research outputs found
Smart agricultural land-use changes and their effects on soil microbial communities enhance the maintenance of soil fertility and sustainable crop production in humid savannas of Ivory Coast
No full textEn Afrique de l'Ouest, les sols de savanes humides se caractérisent par des concentrations extrêmement basses de matières organiques, d'azote minéral, de phosphore et de cations basiques, ce qui limite la production primaire. Ce travail a analysé comment des changements particuliers dans les utilisations des terres peuvent influencer le fonctionnement et la fertilité des sols, pour in fine soutenir la production des agroécosystèmes dans cette zone de savane. Six différents types d'utilisation des terres sur 9 parcelles expérimentales répartis à l’échelle du paysage du centre-sud de la Côte d’Ivoire ont été comparé : (i) le brûlis comme pratique traditionnelle ; (ii) la fertilisation chimique comme pratique conventionnelle ; et le mulching comme pratique innovante, testé (iii) sans insertion de légumineuses ou (iv et v) avec insertion de haricot ou soja dans des cycles de rotations culturales ; (vi) le sol nu était considéré comme une situation de référence (le témoin). Le sol a été prélevé dans 54 sous-parcelles, avant et 3 fois après la mise en place des traitements. Sept activités enzymatiques (activités dénitrifiante, nitrifiante, β glucosidase, N-acétyl-β-D-glucosaminidase, phosphatase acide et alcaline, déshydrogénase) du sol, les principales variables du sol (humidité, carbone organique, azote total, pH et Phosphore assimilable), l'abondance et la diversité des communautés microbiennes impliquées dans le cycle de l’azote (bactéries et archées oxydatrices de l’ammonium ; les genres Nitrobacter et Nitrospira qui jouent un rôle clé dans la production de nitrate ; les bactéries réductrices du nitrite porteuses des gènes nirS ou nirK ; et les bactéries réductrices du N2O porteuses de gènes nosZI ou nosZII). Les résultats ont montré que (i) le C. org, le K, le Mg et les activités enzymatiques du sol ont diminué avec la profondeur du sol, indiquant un faible taux d’accumulation des nutriments dans les profondeurs les plus importantes du sol. Par ailleurs, les durées de jachère (0 à 10 ans) n’ont pas significativement affecté la majorité des propriétés du sol, à l'exception de l’Ntot et du K du sol qui étaient élevés dans les vieilles jachères. De plus, le C. org a diminué en fonction de la durée de la jachère tandis que le Mg a suivi une tendance inverse ; (ii) le type d'utilisation des terres a affecté fortement la plupart des activités enzymatiques du sol et les communautés microbiennes impliquées dans le cycle de l’azote; (iii) les pratiques de mulching pourraient avoir un impact positif sur les caractéristiques du sol et les communautés microbiennes, avec pour conséquence le renforcement du maintien de la fertilité des sols et la durabilité de la production agricole à long terme. D’après les résultats obtenus, la pratique de paillage, possiblement avec insertion de légumineuses, pourrait être moins onéreuse et plus adaptée pour augmenter progressivement et de façon durable la disponibilité en azote dans ces agroécosystèmesIn West Africa, humid savanna soils are characterized by extremely low concentrations of organic matter, mineral nitrogen, phosphorus and basic cations, which limit primary production. We analyzed how particular changes in land-uses can influence the functioning and fertility of soils, to support the production of agroecosystems in this savanna zone. We compared six land-use types at 9 experimental plots across a landscape: traditional slash-and-burn; conventional chemical fertilization; and innovative use of mulching (tested with or without inserting legumes in the crop rotation). Bare soil was also considered as a reference situation. Soil was sampled on the 54 sub-plots, before and 3 times after treatment inception. We surveyed seven soil enzyme activities (denitrification, nitrification, β glucosidase, N-acetyl-β-D-glucosaminidase, acid and alkaline phosphatase, dehydrogenase), key soil variables (moisture, organic C, mineral and total N, pH, and available P) and the abundances and diversity of microbial communities involved in the N cycle (bacterial and archaeal ammonia oxidizers; Nitrobacter; Nitrospira; and nirS-, nirK- and nosZ-like denitrifiers). Our results showed that (i) C. org, K, Mg and soil enzymes activities decreased with soil depth, reflecting a low rate of nutrient accumulation in soil depth. In contrast, fallow periods (0 to 10 years) did not significantly affect the majority of soil properties, excepted soil Ntot and K, which were high in old fallows. In addition, C. org decreased as a function of the fallow period, but Mg follow-up an inverse trend; (ii) the land use type strongly affects most soil enzymatic activities and the microbial communities involved in nutrient cycling; (iii) innovative mulching practices have a positive impact on soil characteristics and microbial communities, thereby maintaining the maintenance of soil fertility and the sustainability of agricultural production in the long term. According to our results, the practice of mulching, possibly with the insertion of legumes, could be less expensive and more appropriate to progressively and sustainably increase nitrogen availability in these agro-ecosystem
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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