1,721,029 research outputs found
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
Development of plant breeding innovations based on natural diversity - Mission impossible?
Full text linkThe discovery of Mendel’s laws of heredity in the 19th century transformed the ancient activity of selective methods from early plant-breeding procedures, dating to the very beginnings of agriculture, to a science. One of the major basic essentials that emerged during the history of scientific plant breeding is the knowledge about the tremendous wealth of genetic variability existing in plants. With an increased understanding of plant biology and plant genes, plant breeders have continuously improved their breeding tools for tapping the potential of genetic diversity to adapt plants to the ever-changing demands of farmers, consumers, and the environment. New Genomic Techniques (NGTs) are tools in plant breeding that make use of genetic diversity by induced mutagenesis directed to a defined genomic location, thus enabling editing of the genome with a precision not feasible before. NGTs render it possible to create genome alterations directly in elite germplasm and promise to shorten the development time for improved cultivars with desired phenotypes. Knowledge about causal sequence motifs for phenotypic variation is the indispensable prerequisite for changing the genetic material of a plant in the desired direction. The availability of high-quality reference genome sequences offers a state-of-the-art framework for identifying functional sequence motifs even in neglected crops like rye (Rabanus-Wallace et al. 2021). Indeed, a genome-wide association study (GWAS) has mapped 676 cross-validated SNPs associated with complex agronomic and quality traits to the Lo7 pseudomolecules with 206 SNPs residing in coding sequences (Siekmann et al. 2021). Followup studies are necessary to advance these GWAS results and to infer the exact causal variants. However, going from genetics to function is a challenging task in rye. For reverse-genetic tools to be functional, its active components have to be delivered to a cell for creating genetic modifications and observing the resulting phenotype. In rye, efficient procedures to investigate the impact of induced variation within a specific gene and to infer gene function by gene silencing, homologous recombination or nontargeted random disruptions (e.g. chemical mutagenesis or transposon mediated mutagenesis) followed by screening a library of individuals for mutations at a specific location are lacking. In a case study unlocking a major QTL controlling fertility restoration of Pampa-CMS in rye, methods to identify the candidate gene such as fine mapping of the mendelian factor underlying the QTL (Hackauf et al. 2012) as well as high-resolution genetic and physical mapping, and allele sequencing (Wilde et al. 2021) have been successfully applied. However, conclusive evidence for malefertility restoration of genetic variants in the identified candidate gene by specific functional assays is owing, as delivery mechanisms for gene-editing that bypass current challenges in tissue culture and regeneration procedures of rye need to be established. As plant-breeding innovations like NGTs seem to be not applicable at least in the short term, improved breeding efforts are crucial for enhancing the competitiveness of rye in agricultural production systems. The natural genetic diversity in rye was the fundamental basis to achieve a series of technological advances that ultimately facilitated the establishment of hybrid breeding, a cutting-edge technology to increase and secure cereal production on finite arable land without increasing water and fertilizer use (Hackauf et al. 2022). The recent implementation of the Gibberellin-sensitive dominant dwarfing gene Ddw1 in a commercial hybrid rye breeding program is paradigmatic for specific genes, and adaptive alleles that govern important agronomic traits in rye. The promising performance observed in extreme environments in 2021 and 2022 triggers an enhanced development of semidwarf hybrids and may initiate a new era of physiological rye breeding that aims to raise the yield potential of rye closer to its biological limit (Hackauf et al. 2022). To conclude, the successful integration of a Mendelian inheritance factor in hybrid rye breeding improves yield potential, lodging resistance, and drought tolerance and is an up-to-date example of reconciling food security and sustainability through plant breeding innovations based on natural diversity
Halbzwerge überzeugen auch beim Roggen
No full textDer Anbau von Roggen leistet nach wie vor einen bedeutenden Beitrag zur Kulturartenvielfalt in unserer Agrarlandschaft. Im Gegensatz zu anderen Getreidearten muss der Roggen seine Anbauwürdigkeit jedoch stets aufs Neue legitimieren. So haben die deutschen Landwirte die Anbaufläche von Roggen für die Ernte 2017 mit 546.000 ha um weitere 4,9 % bzw. 28.400 ha im Vergleich zum Vorjahr eingeschränkt.1 Dies hat vielfältige, insbesondere ökonomische Gründe und zeigt: damit der Roggen auch auf den etwas besseren Standorten als risikoarm zu führende Getreideart wettbewerbsfähig bleibt, ist er ebenso wie alle anderen Kulturpflanzen auf eine kontinuierliche züchterische Verbesserung angewiesen. Die Züchtungsforschung am Julius Kühn-Institut (JKI) leistet hierfür wissenschaftliche Vorarbeiten
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Schlussbericht zum Projekt
No full textDas Verbundvorhaben TERTIUS erschloss genetische Vielfalt aus Roggen (Secale cereale L.), um die Trockenstresstoleranz und Wassernutzungseffizienz von deutschem Winterweizen (Triticum aestivum L.) zu verbessern. In vier Prüfjahren (2021–2024) wurde nur 2022 eine ausgeprägte Dürre beobachtet, eine wissenschaftlich entscheidende Gelegenheit, die Verletzlichkeit der Weizenproduktion unter Praxisbedingungen zu quantifizieren. Dabei zeigte sich eine Ertragsdepression von rund 14 %. Die Analyse von 1RS-Translokationen aus Roggen offenbarte eine häufige Integration in Eliteweizen und belegte, dass durch natürliche Rekombination innerhalb dieser Segmente neue genetische Diversität und höhere Ertragsstabilität unter Dürre erreicht werden können. TERTIUS demonstriert die strategische Bedeutung von Roggentranslokationen für die Züchtung klimaresilienter Qualitätsweizen in Deutschland und Europa
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