1,720,956 research outputs found
Transgénese de genes específicos de células estaminais via CRISPR/Cas9 para o estudo da regeneração no platelminta Macrostomum lignano
No full textDissertação de Mestrado em Biologia Celular e Molecular apresentada à Faculdade de Ciências e TecnologiaA regeneração de tecidos é um processo que está dependente da capacidade de proliferação e diferenciação de células estaminais. No entanto, os mecanismos moleculares envolvidos neste processo são ainda uma incógnita, tornando ainda mais fascinante este atributo tão raro em alguns animais. Macrostomum lignano é um platelminta marinho que apresenta um conjunto qualidades únicas que fazem com que se adeqúe perfeitamente ao estudo de regeneração e células estaminais. É de fácil manutenção, transparente, tem um curto tempo de vida, produz ovos individuais fertilizados o que possibilita a criação de organismos transgénicos via micro-injecção. Além de todas as características descritas tem capacidade de regeneração ao longo do corpo, apenas possível devido à população pluripotente de células estaminais denominada neoblastos. O estudo dos neoblastos possibilita a compreensão dos mecanismos envolvidos no processo de regeneração.Neste estudo foi possível desenvolver linhas transgénicas de M. lignano que marcam os neoblastos pela integração de uma proteína fluorescente pelo sistema CRISPR/Cas9 no locus de um gene específico dos neoblastos, H2AX. Esta linha foi um ponto de partida para a criação de linhas transgénicas duplas que marcam neoblastos assim como variados tipos celulares com proteínas fluorescentes distintas. A expressão fluorescente de uma linha dupla que marca neoblastos e células musculares após amputação permitiu identificar células progenitoras, neoblastos destinados a se diferenciarem em determinado tipo celular. A criação destas linhas transgénicas possibilitou o acompanhamento in vivo do comportamento dos neoblastos no processo de regeneração assim como a separação de diferentes populações de neoblastos nunca identificadas.Além de nos dar uma perspectiva mais ampla da função dos neoblastos, este projecto permitiu a melhor compreensão do processo de diferenciação destas células após amputação. O desenvolvimento da tecnologia CRISPR/Cas9 posiciona Macrostomum lignano como o platelminta de eleição para o estudo de comportamento celular in vivo e para o estudo da genómica funcional dos neoblastos tanto em homeostasia como em regeneração. Também alarga o seu estudo em diferentes áreas como cancro, manutenção genómica e envelhecimento.Regeneration of lost or damaged tissues is dependent on proliferation and differentiation of stem cells. The understanding of this molecular process is one of the longstanding scientific problems that require a suitable model organism. The recently developed model Macrostomum lignano is a marine free‐living flatworm with a unique set of biological properties perfectly positioned for the study of stem cells and regeneration. It is easy to culture, transparent, has a short generation time and produces single-cell fertilized eggs, enabling transgenesis via microinjection. Whole-body regeneration in flatworms is fueled by a pluripotent population of stem cells called neoblasts. Studying the biology of neoblasts improves our understanding of the mechanisms involved in regeneration. In the current project we were able to develop by microinjection a M. lignano transgenic line labeling neoblasts by CRISPR/Cas9‐mediated knock‐in of a fluorescent protein into a neoblast‐specific gene, H2AX. Such line was a starting point for generating multiple double transgenic lines labeling both neoblasts and differentiated cell types tagged with distinct fluorescent proteins. Fluorescent protein expression in a double transgenic line with a muscle-specific marker allowed identification of progenitor cells upon regeneration, a neoblast population committed to differentiate into specific cell-types. These transgenic lines allow for in vivo tracking of neoblast behavior during regeneration and isolation of several never identified stem cell populations for further characterization.This project improves our understanding of the molecular mechanisms of neoblast differentiation and provides a broader multidimensional image of the function of stem cells in the process of regeneration. The enlargement of its experimental potential places M. lignano as the invertebrate model organism of choice for studying in vivo cell behavior and stem cell-specific gene function in tissue regeneration and homeostasis. As well as expand its value in other research fields as cancer, genome maintenance and ageing
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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