1,720,958 research outputs found
Unveiling the plant-associated microbiome responses and nitrification inhibition aspects of perennial intermediate wheatgrass (Thinopyrum intermedium)
Full text linkPerennialization of agriculture has recently garnered attention as a nature-based solution (NBS) to complement predominantly annual cropping systems, offering a pathway toward sustainable agriculture and enhanced protection of agroecosystems. In this regard, the perennial intermediate wheatgrass, Thinopyrum intermedium, trade name Kernza®, has been proposed as a model plant for achieving perennialization of cereal cropping systems. Kernza® provides a broad range of ecosystem services, including enhanced carbon sequestration, enhanced biodiversity, and regulation of the nitrogen (N) cycle. Some studies reported regulated nitrification in Kernza® fields through reduced N2O emissions, low N leaching, and high legacy N. These traits indicate a plant-exerted control of nitrification through the secretion of bioactive metabolites, a concept known as biological nitrification inhibition (BNI). However, no study had investigated the mechanism behind these BNI traits of Kernza®. Relatedly, existing BNI studies have largely been confined to the identification and testing of single and novel metabolites. Moreover, while some studies have reported the ability of Kernza® to stimulate microbial activity and enhance microbial diversity, there is currently no study in a European context on the potential influence of Kernza® on the rhizosphere microbiome. Thus, this doctoral study aimed to fill these knowledge gaps.
The first study used a metabolome fingerprinting approach to profile the metabolome of the Kernza® biomass collected from the field and root exudates collected under N sources (ammonium (NH4+) versus nitrate (NO3-)) in a hydroponic system. Multiple nitrification inhibitors, including several phenolic metabolites, were identified in higher quantities in the biomass of Kernza® than in annual wheat. These metabolites were also concurrently exuded in higher quantities by the roots of Kernza® under NH4+-N source than NO3--N source. Bioassays involving multiple ammonia-oxidising bacteria and archaea (AOB and AOA) confirmed the antimicrobial properties of crude root exudates of Kernza®, as well as individual metabolites such as caffeic acid, vanillic acid, vanillin, and phenylalanine. Soil incubation experiments further demonstrated the nitrification inhibition potential of all tested metabolites, except phenylalanine. This study presents the initial evidence elucidating the mechanisms by which Kernza® regulates nitrification and clarifies the function of Kernza’s® metabolome in mediating nitrification inhibition.
In the second study, a pairwise combinatorial approach was employed to assess the interactions among biochemically distinct metabolites co-exuded by Kernza® – caffeic acid, vanillic acid, vanillin, and phenylalanine – against multiple ammonia-oxidisers and soil nitrification. It was found that the metabolites interacted both synergistically and antagonistically against the test strains and soil nitrification, with antagonism being the most predominant interaction among the metabolites. Caffeic acid exhibited single agent dominance (SAD), dominating all other metabolites in all combinations. Furthermore, nitrifiers responded differentially to the metabolites – affirming that nitrifiers are differentially sensitive to inhibitors. Both individual and paired metabolites inhibited the growth of multiple AOB and AOA, as well as soil nitrification – suggesting that both synergism and antagonism did not impair the inhibitory potentials of the metabolites. This evidence suggests that biochemically distinct metabolites exuded by Kernza® and other BNI-positive plants may be interacting in diverse ways in the rhizosphere to suppress nitrification.
The third study assessed the impact of Kernza®-induced perennialization on rhizomicrobiome and root endophytes in comparison to annual wheat under an agroclimatic gradient (Sweden, France, and Belgium). The results suggest pronounced similarities in the rhizobacterial composition of Kernza® and annual wheat, with no significant difference in the alpha diversity of their rhizomicrobiome. Beta diversity analysis revealed that factors such as country (agroclimatic conditions), sampling depth (spatial), and year (temporal) rather exerted greater influence than crop type. Notwithstanding, Kernza® promoted the stability of the rhizomicrobiome than annual wheat based on year-on-year comparison – suggesting that perennialization has the ability to protect rhizomicrobiome from ecological perturbation. Moreover, Kernza® recruited and internalised a higher proportion of the rhizosphere microbiome into its root tissues compared to annual wheat, indicating a potential role of crop-associated microbiomes in the lifecycle of Kernza®. Furthermore, an environment-wide comparison with agroecologically relevant database revealed that Kernza®, compared to annual wheat, harboured a significant proportion of rhizobacterial taxa associated with the rhizosphere and grassland ecosystems – supporting the notion that Kernza® shares ecological characteristics with natural grasslands. This study adds to the growing body of knowledge on the rhizosphere ecology of Kernza® and provides further evidence for the ecosystem service potential of Kernza®.Der mehrjährige Anbau in der Landwirtschaft hat in letzter Zeit als naturbasierte Lösung (nature-based solution, NBS) zur Ergänzung der überwiegend einjährigen Anbausysteme Aufmerksamkeit gewonnen und bietet einen Weg zu einer nachhaltigen Landwirtschaft und einem verbesserten Schutz der Agrarökosysteme. In diesem Zusammenhang wurde das Mehrjährige Weizengras (Thinopyrum intermedium), Handelsname Kernza®, als Modell-pflanze für die mehrjährige Bewirtschaftung von Getreideanbausystemen vorgeschlagen. Kernza® erbringt umfangreiche Ökosystemdienstleistungen, darunter Kohlenstoffbindung, Förderung der biologischen Vielfalt und Regulierung des Stickstoffkreislaufs (N). Einige Studien zeigten Eigenschaften einer regulierten Nitrifikation in Kernza®-Feldern, wie z. B. reduzierte N2O-Emissionen, geringe N-Auswaschung und hohen N-Rückhalt. Diese Eigenschaften stellen eine von der Pflanze ausgeübte Kontrolle der Nitrifikation durch die Sekretion bioaktiver Metaboliten dar, ein Konzept, das als biologische Nitrifikations-hemmung (biological nitrification inhibition, BNI) bekannt ist. In keiner Studie wurde jedoch der Mechanismus hinter diesen BNI-Eigenschaften bei Kernza® untersucht. In diesem Zusammenhang beschränkten sich die bisherigen BNI-Studien weitgehend auf die Identifizierung und Prüfung einzelner und neuartiger Metaboliten. Darüber hinaus haben zwar einige Studien die Fähigkeit von Kernza® berichtet, die mikrobielle Aktivität zu stimulieren und die mikrobiale Diversität zu erhöhen, doch gibt es derzeit keine Studie in einem europäischen Kontext über den potenziellen Einfluss von Kernza® auf das Mikrobiom der Rhizosphäre. Ziel dieser Doktorarbeit war es daher, diese Wissenslücke zu schließen.
In der ersten Studie wurde ein Metabolom-Fingerprinting-Ansatz verwendet, um das Metabolom der Kernza®-Biomasse, die auf dem Feld gesammelt wurde, und das der Wurzelexsudate, die unter N-Quellen (Ammonium (NH4+) versus Nitrat (NO3-)) in einem hydroponischen System gesammelt wurden, zu analysieren. Mehrere Nitrifikations-inhibitoren, darunter verschiedene phenolische Metaboliten, wurden in der Biomasse von Kernza® in größeren Mengen nachgewiesen als in einjährigem Weizen. Diese Metaboliten wurden auch gleichzeitig von den Wurzeln von Kernza® unter NH4+-N-Quelle signifikant mehr ausgeschieden als unter der NO3--N-Quelle. Bioassays mit mehreren ammonium-oxidierenden Bakterien und Archaeen (AOB und AOA) bestätigten die antimikrobiellen Eigenschaften der gewonnenen Wurzelexsudate von Kernza® sowie einzelner Metaboliten wie Kaffeesäure, Vanillinsäure, Vanillin und Phenylalanin. In Bodeninkubationsexperimenten wurde außerdem das nitrifikationshemmende Potenzial aller getesteten Metaboliten außer Phenylalanin nachgewiesen. Diese Studie lieferte den ersten Nachweis für die Rolle des Kernza®-Metaboloms bei der Nitrifikationshemmung.
In der zweiten Studie wurde ein paarweiser kombinatorischer Ansatz angewandt, um die Wechselwirkungen zwischen den biochemisch unterschiedlichen Metaboliten, die Kernza® gemeinsam produziert – Kaffeesäure, Vanillinsäure, Vanillin und Phenylalanin – gegen mehrere Ammonium-Oxidationsmittel und die Nitrifikation im Boden zu bewerten. Es wurde festgestellt, dass die Metaboliten sowohl synergistisch als auch antagonistisch gegen die Teststämme und die Bodennitrifikation wirkten, wobei der Antagonismus die vorherrschende Wechselwirkung zwischen den Metaboliten war. Kaffeesäure zeigte eine Einzeldominanz (single agent dominance) und dominierte alle anderen Metaboliten in allen Kombinationen. Außerdem reagierten die Nitrifikanten unterschiedlich auf die Metaboliten, was bestätigt, dass die Nitrifikanten unterschiedlich empfindlich auf Hemmstoffe reagieren. Sowohl einzelne als auch gepaarte Metaboliten hemmten das Wachstum mehrerer AOB und AOA sowie die Nitrifikation im Boden – was darauf hindeutet, dass sowohl Synergismus als auch Antagonismus das Hemmungspotenzial der Metaboliten nicht beeinträchtigten. Dies deutet darauf hin, dass biochemisch unterschiedliche Metaboliten, die von Kernza® und anderen BNI-positiven Pflanzen ausgeschieden werden, in der Rhizosphäre auf unterschiedliche Weise zusammenwirken, um die Nitrifikation zu unterdrücken.
In der dritten Studie wurden die Auswirkungen der Kernza®-induzierten Mehrjährigkeit auf das Rhizomikrobiom und die Wurzelendophyten im Vergleich zu einjährigem Weizen unter einem agroklimatischen Gradienten (Schweden, Frankreich und Belgien) untersucht. Die Ergebnisse deuten auf eine ausgeprägte Ähnlichkeit in der rhizobakteriellen Zusammensetzung von Kernza® und einjährigem Weizen hin, wobei es keinen signifikanten Unterschied in der Alpha-Diversität ihres Rhizomikrobioms gibt. Die Analyse der Beta-Diversität ergab, dass Faktoren wie das Land (agroklimatische Bedingungen), die Beprobungstiefe (räumlich) und das Jahr (zeitlich) einen größeren Einfluss ausübten als die Kulturart. Dennoch förderte Kernza® im Jahresvergleich die Stabilität des Rhizomikrobioms gegenüber einjährigem Weizen – was darauf hindeutet, dass eine mehrjährige Kultur das Rhizomikrobiom vor ökologischen Störungen schützen kann. Außerdem rekrutierte und internalisierte Kernza® einen höheren Anteil des Rhizosphären-Mikrobioms in seine Wurzelgewebe im Vergleich zu annualem Weizen, was auf eine potenzielle Rolle der pflanzen-assoziierten Mikrobiome im Lebenszyklus von Kernza® hinweist. Darüber hinaus ergab ein Vergleich verschiedener Umwelten mit einer agrarökologischen Datenbank, dass Kernza® im Vergleich zu einjährigem Weizen einen signifikanten Anteil an rhizobakteriellen Taxa beherbergt, die mit der Rhizosphäre und Grasland-Ökosystemen assoziiert sind – was die Annahme unterstützt, dass Kernza® ökologische Merkmale mit natürlichem Grasland teilt. Diese Studie ergänzt das zunehmende Wissen über die Rhizosphärenökologie von Kernza® und liefert weitere Belege für das Potenzial von Kernza® hinsichtlich Ökosystemdienstleistungen
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
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