1,721,007 research outputs found
Rice bacterial diseases due to Xanthomonas oryzae in Burkina Faso : diversity and identification of locally-adapted resistance sources
No full textLa bactériose vasculaire du riz (BLB) et à stries foliaires (BLS) causées respectivement par Xanthomonas oryzae pv. oryzae (Xoo) et X. oryzae pv. oryzicola (Xoc) sont deux maladies émergentes en Afrique de l'Ouest, suite à l'expansion de la culture du riz et à l'introduction de variétés à haut rendement au cours de ces dernières décennies. Trois nouvelles races de Xoo ont été caractérisées en Afrique dont on a montré, sur la base d'une analyse génétique, leur spécificité africaine. En revanche, une étude réalisée sur une dizaine de souches de Xoc isolées au Mali en 2003, démontre qu'elles sont apparentées à des souches de Xoc asiatiques. En Asie, plusieurs gènes de résistance à Xoo ont été identifiés et déployés dans les programmes de lutte contre BLB. Cependant aucun gène de résistance à Xoc n'a été encore identifié chez le riz. Les objectifs de notre étude étaient (i): d'implémenter les collections de souches de Xoo et Xoc Africaines disponibles mais incomplètes, à l'aide de nouvelles campagnes d'échantillonage réalisées de 2009 à 2012 dans différentes zones agroécologiques du Burkina Faso et du Mali, (ii) de déterminer la diversité génétique de ces souches, (iii) d'identifier et caractériser de nouvelles sources de résistance contre BLB et BLS au sein d'accessions de riz cultivées au Burkina Faso. Nos résultats ont montré que les souches africaines de Xoc sont hautement variables tant d'un point de vue génétique que du pouvoir pathogène. L'analyse par PCR de deux effecteurs de types III conservés (xopAJ et xopW) permet de différencier les souches de Xoc en deux groupes, xopAJ étant absent dans la majorité des souches et une insertion de 1050 bp étant détectée dans la séquence codante de xopW de certaines souches. Néanmoins, il apparait que la forte diversité génétique des Xoc n'est pas corrélée à leur origine géographique, ni à la période de collecte, ou à la nature de l'hôte. Les souches de Xoo caractérisées appartiennent toutes à la race A1 qui n'avait pas encore été signalée au Mali. Au regard de la diversité des souches et de leur évolution, il est important d'envisager un plan de surveillance épidémiologique à plus large échelle des populations de Xo dans les régions concernées en Afrique de l'Ouest. Enfin, nous avons montré que certaines variétés de riz cultivées au Burkina Faso présentent un phénotype de résistance spécifique des souches africaines de Xoo et ce, à tous les stades de développement de la plante. Ces données originales contrastent par rapport au phénotype des lignées de riz résistantes de référence (Xa4, xa5 et Xa7 efficaces uniquement au stade de tallage maximum). Eu égard à l'absence de gènes de résistance dans le riz efficaces contre Xoc, ces variétés qui constituent également une source de résistance efficaces contre la diversité des souches de Xoc africaines, offrent potentiellement un nouveau moyen pour assurer le contrôle du BLS au Burkina Faso et éventuellement dans d'autres pays Africains.Bacterial Leaf Blight (BLB) and Bacterial Leaf Streak (BLS) diseases respectively caused by Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae. pv oryzicola (Xoc) are two emerging diseases of rice in West Africa, due to the recent expansion of rice cultivation and introduction of improved rice varieties over the last decade. Three news Xoo races were characterized based on genetic analysis, demonstrating their african specificity. In contrast, a study achevied on about ten Xoc strains isolated in Mali in 2003, show that they are related to asian Xoc strains. In Asia, several R genes against Xoo have been identified and deployed in breeding program to control BLB. In contrast, no R gene against Xoc has been identified in rice. The objectives of this PhD thesis are to (i) complete the Xo collections of African isolates upon annual sampling operated from 2009 to 2012 in various agroecological areas of Burkina Faso and Mali, (ii) determine the genetic diversity of these strains , (iii) identify and characterize news sources of resistance genes to BLB and BLS within rice accessions cultivated in Burkina Faso.Our results showed that african Xoc are highly diverse genetically and phenotypically. PCR-based analyse of two conserved type III effector gene (xopAJ and xopW) differentiated two groups of Xoc strains, with xopAJ not detected in a majority of African Xoc strains and 1050 bp insertion detected in xopW gene for few strains. However, the high genetic diversity observed among the Xoc strains is not correlated to geographical origin, sampling data or host plant species. Xoo strains characterized belong all to race A1 previously reported by Gonzalez et al. (2007) in Burkina Faso. Given the diversity of X. oryzae strains and their evolution, it is essential to establish a large scale epidemiological monitoring of Xo populations in concerned regions in west Africa.At last, some accessions cultivated in Burkina Faso showed specific resistance to african Xoo strains at all plant development stages. These original data contrast with rice lines carring Xa4, xa5 and Xa7 resistance genes against BLB, which are only effective at maximun tillering stage.Given no sources of effective resistance genes against BLS is available in rice, these accessions which were also efficient against a set of Xoc strains representative of the diversity in Africa, represent a huge potential source for the control of BLS in Burkina Faso, and eventually in others african countries
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
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
- …
