1,720,953 research outputs found
Molecular characterization and photomyxotrophic growth of a cyanobacterium of the genus Synechocystis that produces the poly-β-hydroxybutyrate biopolymer
No full textEl uso excesivo de materiales plásticos de origen petroquímico ha causado uno de los problemas ambientales más grandes de los últimos años. La biotecnología se ha enfocado en abordar esta problemática a través de microorganismos que sintetizan polímeros sustentables y totalmente biodegradables, como: el poli-β-hidroxibutirato (PHB). Este biopolímero es producido de forma natural por algunos microorganismos incluyendo a la cianobacteria modelo Synechocystis sp. PCC 6803, la cual tiene la capacidad de llevar a cabo crecimiento fotoautotrófico, mixotrófico o heterotrófico en medio de cultivo suplementado con glucosa. Esta cepa cuenta con su genoma secuenciado y los genes de la vía de síntesis de PHB ya han sido descritos. Sin embargo, debido a las restricciones de uso que presentan las cepas modelos es importante identificar nuevas cepas productoras naturales de este biopolímero, que brinden la posibilidad de encontrar características sobresalientes a las ya conocidas. La taxonomía de cianobacterias basadas en el DNA se centra en las similitudes entre secuencias conservadas como 16S ribosomal y diferencias entre la el 16S-23S espaciador ribosomal intergénico (ITS). El análisis de las cianobacterias de la colección del laboratorio, basada en la amplificación del gen phaC evidenció a la cepa B6B como una cianobacteria con potencial en la producción PHB de manera natural. En este sentido, el objetivo del presente estudio fue evaluar el crecimiento y producción de PHB por las cepas Synechocystis sp. PCC 6803 (control) y B6B diferentes medios de cultivo: fotoautótrofa (BG11) y fotomixotróficas que incluyen BG11 adicionada con glucosa (G+) o acetato (A+) y/o limitación de nitrógeno (N-). Así mismo, se llevó a cabo la caracterización molecular de B6B para su identificación a nivel de género. El análisis de la región ITS de la cepa B6B mostró un alto porcentaje de identidad con especies del género Synechocystis (94.48%) y un alto porcentaje de GC (42.9%), además de codificar para un tRNAIle característico del género. Así mismo, los árboles filogenéticos obtenidos con secuencias rRNA 16S e ITS se agrupó a la cepa B6B en el clado de Synechocystis. Las regiones ITS de B6B y PCC 6803 presentan 21 nucleótidos de diferencias entre sí, mismos que permitieron diferenciar a las dos cepas mediante el análisis de RFLP. Las curvas de crecimiento en medio BG11 obtenidas tanto por conteo celular como por mediciones de densidad óptica (730 nm) mostraron una mayor velocidad de ...The excessive use of petrochemical-based plastics has caused one of the biggest environmental problems in recent years. Biotechnology has focused on addressing this problem through microorganisms that synthesize sustainable and fully biodegradable polymers, such as poly-β-hydroxybutyrate (PHB). This biopolymer is produced naturally by some microorganisms, including the model cyanobacteria Synechocystis sp. PCC 6803 that can carry out photoautotrophic, mixotrophic, or heterotrophic growth in a culture medium supplemented with glucose. This strain has its genome sequenced, and the genes of the PHB synthesis pathway have been described. However, due to the restrictions of use presented by the model strains, it is important to identify new natural producing strains of this biopolymer, which offer the possibility of finding outstanding characteristics to those already known. The DNA-based taxonomy of cyanobacteria focuses on the similarities among conserved sequences such as 16S ribosomal and differences among the 16S-23S intergenic ribosomal spacer (ITS). The analysis of the cyanobacteria from the laboratory collection, based on the amplification of the phaC gene, showed the B6B strain as a cyanobacterium with the potential to produce PHB naturally. Therefore, the objective of the present study was to evaluate the growth and production of PHB by the Synechocystis sp. PCC 6803 (control) and B6B strain in different media: photoautotrophic (BG11) and photomyxotrophic (BG11 added with glucose (G+) or acetate (A+)) and/or nitrogen limitation (N-) culture media. Besides, the molecular characterization of B6B was carried out for its identification at the genus level. The ITS region of the B6B strain showed a high percentage of GC (42.9%) and a high percentage of identity with species of the genus Synechocystis (94.48%), in addition to coding for the characteristic tRNAIle of the genus. The phylogenetic trees obtained with 16S rRNA and ITS sequences grouped the B6B strain in the Synechocystis clade. The ITS regions of B6B and PCC 6803 showed 21 nucleotides of differences between them, which allowed the two strains to be differentiated by RFLP analysis. The growth curves in BG11 medium obtained by cell counting and optical density measurements (730 nm) showed a higher growth rate for the B6B strain (μmax = 1.36) compared to the model strain (μmax = 0.91). Under photomyxotrophic conditions, biomass production was inversely proportional to PHB production for both ..
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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