1,720,972 research outputs found
Individual plant genetics reveal the control of local adaptation in European maize landraces
No full textAbstract Background European maize landraces encompass a large amount of genetic diversity, allowing them to be well-adapted to their local environments. This diversity can be exploited to improve the fitness of elite material in the face of a changing climate. Results We characterized the genetic diversity of 333 individual plants from 40 European maize landrace populations (EMLPs). We identified five genetic groups that mirrored the proximities of their geographical origins. Fixation indices showed moderate differentiation among genetic groups (0.034 to 0.093). More than half of the genetic variance was observed to be partitioned among individuals. Nucleotide diversity of EMLPs decreased significantly as latitude increased (from 0.16 to 0.04), suggesting serial founder events during maize expansion in Europe. GWAS with latitude, longitude, and elevation as response variables identified 28, 347, and 68 significant SNP positions, respectively. We pinpointed significant SNPs near dwarf8, tb1, ZCN7, ZCN8, and ZmMADS69 and identified 126 candidate genes with ontology terms indicative of local adaptation in maize, regulating adaptation to diverse abiotic and biotic environmental stresses. Conclusions This study suggests a quick and cost-efficient approach to identifying genes involved in local adaptation without requiring field data. The EMLPs used in this study have been assembled to serve as a continuing resource of genetic diversity for further research aimed at improving agronomically relevant adaptation traits.Open-Access-Publikationsfonds 202
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
Schätzung von Kreuzungsparametern unter besonderer Berücksichtigung von epistatischen Effekten und einer Optimierung des Kreuzungszuchtverfahrens beim Meerschweinchen in Bolivien
Full text linkSchätzung von Kreuzungsparametern unter besonderer Berücksichtigung von epistatischen Effekten und Optimierung des Kreuzungszuchtverfahren beim Meerschweinchen in Bolivien Die vorliegende Arbeit befasst sich mit dem Meerschweinchen als einheimischem Fleischlieferant in den Andenstaaten Lateinamerikas, das im Rahmen der ländlichen Entwicklung durch Züchtung und entsprechende Haltung zu einer besseren Fleischversorgung und evt. zu einer Einkommensquelle insbesondere für Kleinbauern beitragen soll. Ziel der Arbeit ist es, die Kreuzungsparameter, insbesondere epistatische Effekte, zwischen einer synthetischen kleinrahmigen nativen Linie, bestehend aus 29 Herkünften Boliviens, und einer importierten großrahmigen Linie aus Peru unter semi-intensiven/semi-extensiven "modernen" Haltungsbedingungen zu schätzen und daraus Schlussfolgerungen für die Optimierung von Zuchtsystemen zu ziehen. In der Einleitung werden zunächst die biologische Besonderheiten des Meerschweinchens sowie die kulturelle und gesellschaftliche Bedeutung des Meerschweinchens und Haltungssysteme kurz beschrieben. Der Literaturteil befasst sich mit den Genwirkungen bei Kreuzungen, insbesondere den nicht-additiven Geneffekten und der Planung und Optimierung von Kreuzungssystemen. Außerdem wird die Reproduktions- und Produktionsleistung beim Meerschweinchen in Rein- und Kreuzungszucht dargestellt. Der eigenen Untersuchung liegen die Daten von 2857 ersten und zweiten Würfen bzw. von 7745 lebend geborenen Jungtieren vor, die aus der Verpaarung von ca. 391 Böcken mit 1688 Weibchen hervorgingen. Es handelt sich um die am Zuchtprojekt "Mejocuy" der Universidad Mayor de San Simón in Cochabamba, Bolivien, entwickelten nativen synthetischen bolivianischen und der importierten peruanischen Linie sowie 12 daraus abgeleiteten Kreuzungsgruppen verschiedener Generationen (reziproke F1s, reziproke Rückkreuzungen, F2, Vorstufen einer Wechselkreuzung sowie eine synthetische Linie mit je 50% Genanteil der beiden Ausgangspopulationen). Der Schätzung der Kreuzungsparameter liegen das Jakubec-Modell mit drei verschiedenen epistatischen Effekten (Additiv x Additiv-Interaktionen, Additiv x Dominanz-Interaktionen, Dominanz x Dominanz-Interaktionen) sowie das Dickerson-Modell mit dem Rekombinationsverlust als epistatischem Effekt auf individueller (Nachkommen-), maternaler (individueller), paternaler (Paarungspartner-) und großmütterlicher (maternaler) Ebene zu Grunde. Auf Grund der Interkorrelation von Parametern (Multikollinearität) sowie für eine gezielte Herausstellung von Parametern für praktische Züchtungsmethoden und -strategien wurde die Anzahl der Parameter je genetisches Modell auf fünf mit jeweils einem epistatischen Effekt pro Modell beschränkt: Dickerson-Modell: gi, hi, ri, gm, hm bzw. gnk, hnk, rnk, gi, hi; Jakubec-Modell aa: gi, di, aai, gm, dm bzw. gnk, dnk, aank, gi, di; Jakubec-Modell dd: gi, di, ddi, gm, dm bzw. gnk, dnk, ddnk, gi, di. Die synthetische bolivianische Linie stellt die Bezugsbasis dar. GLS- bzw. LS-Zuchtgruppenmittelwerte und Kreuzungsparameter wurden für Merkmale der Gewichts- und Wachstumsleistung, der Schlachtleistung, der Reproduktionsleistung sowie für Kriterien der Gesamtproduktivität geschätzt. Die vorherrschenden Kreuzungseffekte sind Linienunterschiede, die bei den Produktionsmerkmalen positiv gerichtet sind, bei der Anzahl Nachkommen pro Muttertier bzw. pro metabolisches Muttergewicht und Halbjahr negativ. Die genetischen Modelle sowie die Ergebnisse sind im Gesamtzusammenhang diskutiert, und es werden Empfehlungen für Zuchtsysteme mit den untersuchten Linien für die am Untersuchungsstandort spezifischen saisonalen und wirtschaftlichen Verhältnisse sowie für die Selektion gegeben.Estimation of Crossbreeding Parameters with Special Consideration of Epistatic Effects and Optimisation of Crossbreeding Procedures For Guinea Pigs in Bolivia The present study investigates the guinea pig as a native animal for meat production in the Andean countries of Latin America. In the framework of rural development the guinea pig can contribute to a better meat supply and a source of income especially for small holders by improving breeding and management. The objective of this study is to estimate crossbreeding parameters, focusing on epistatic effects, from crossings between a small framed synthetic native line consisting of 29 Bolivian strains and an imported line from Peru selected for body weight, kept under semi-intensive/semi-extensive "modern" management conditions. Conclusions for the optimisation of breeding systems should also be derivated. In the introduction first the special biological charcteristics as well as the cultural and symbolic meaning of the guinea pig, and management systems, are briefly described. The literature part treats gene effects in crossbreeding, especially non-additive gene effects, as well as the planning and optimization of crossbreeding systems. Also a literature review of the guinea pig reproduction and production performance in pure- and crossbreeding is presented. In the present study, data from 2857 first and second litters and 7745 progenies, stemming from the matings of 391 bucks with 1688 dams were analysed. The animals belong to a native synthetic Bolivian line, developed at the Universidad Mayor de San Simón, Cochabamba, Bolivia, and an imported Peruvian line as well as to 12 crossbreeding groups derived from these stocks: reciprocal F1s, reciprocal backcrosses, F2, pre-rotational groups and a synthetic line with 50% gene proportion of each purebred line. The basic model for the estimation of crossbreeding parameters is the Jakubec model with three different kinds of epistatic effects (additive x additive interactions, additive x dominance interactions, dominance x dominance interactions) and the Dickerson model with the recombination loss as epistatic effect on the individual (progeny), maternal (individual), paternal (male mating partner) and grandmaternal (maternal) level. Because of the intercorrelation of parameters (multicolinearity) and with the objective to estimate the most relevant parameters for practical breeding methods and strategies the number of parameters per genetic model was restricted to five with one epistatic effect, respectively: Dickerson-Modell: gi, hi, ri, gm, hm and gpr, hpr, rpr, gi, hi; Jakubec-Modell aa: gi, di, aai, gm, dm and gpr, dpr, aapr, gi, di; Jakubec-Modell dd: gi, di, ddi, gm, dm and gpr, dpr, ddpr, gi, di (i: individual, m: maternal, pr: progeny). The synthetic native Bolivian line was considered as reference. GLS- and LS-breeding group means and crossbreeding parameters were estimated for body weight and growth traits, reproduction traits and productivity traits. The prevailing crossbreeding effects are line differences with positive signs for production traits and with negative signs for the number of progeny per dam and per metabolic dam weight in the first half year of production. The genetic models and the results are discussed in a global context and recommendations are derived for breeding systems and selection for the investigated lines under the specific seasonal and economical conditions prevailing at Cochabamba, Bolivia
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
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