1,720,953 research outputs found
Polyvinyl Alcohol - Polyvinyl Pyrrolidone and Polycaprolactone Based Matrices for Cardiac Tissue Engineering Applications
No full textCardiovascular diseases (CVDs) are leading cause of death in the developed and industrialised world and are responsible for approximately ~30% of all global death. In recent years, stem cell-based cardiac tissue engineering (CTE) has emerged as promising technology for the treatment of CVDs in severely damaged heart. The present study deals with the development of polymeric construct for CTE applications. In the first set of experiments, polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) blended film and nanofiber were fabricated and effects of cross-linker and plasticizers on their physico-chemical and biological properties were analyzed. In the second set of experiments, random and aligned polycaprolactone (PCL) nanofibers were spun by electrospinning and were characterized for their application in CTE. Results showed that, PVA-PVP blends could be successfully developed as biodegradable, haemocompatible and cytocompatible cardiac patches with desirable mechanical properties. Optimized molar ratio of PVA, PVP and plasticizers resulted in films, which were dry at room temperature and had desirable folding endurance value (FEV) of at least 300, tensile strength of 5-30 MPa and, percentage elongation at break of more than 250%. Upon contact with PBS, these PVA-PVP films formed hydrogel patches having the tensile strength of 1.3 to 3.0 MPa and supported the attachment, viability and proliferation of H9C2 cardiac cells and primary neonatal cardiomyocytes (CMs). In vivo transplantation of the PVA-PVP patches into subcutaneous pouch and on the heart revealed them to be biodegradable, biocompatible and safe for use. The PVA-PVP blends could also be electrospun to develop nanofibrous matrices (av. dia. 100-200 nm). The study further showed that both random and aligned nanofibrous matrices (av. dia: 350-850 nm) could also be successfully spun from PCL by electrospinning on copper and stainless steel collectors, respectively. Collagen-coated aligned PCL nanofibers showed significantly higher cell adhesion, proliferation and, enhanced cell growth of H9C2 cardiac cells when compared to random PCL nanofibers. Moreover, aligned PCL nanofibers showed an ability to control the orientation of the cells in parallel direction of fibers, thus providing an effective way to control anisotropic nature under in vitro condition. The umbilical cord matrix (UCM)-derived mesenchymal stem cell (MSCs) and adult foreskin-derived induced pluripotent stem cells (iPSCs) were also differentiated into CMs for subsequent construction of cardiac tissue construct. UCM-derived MSCs were isolated successfully by routine enzymatic digestion and a non-enzymatic explant culture method and characterized based on their microscopic observation, differentiation into different lineages such as chondrocytes, osteocytes and adipocytes and surface marker expression of CD34, CD45, CD73, CD14, CD19, HLA-DR, CD90, CD105 by flow cytometry analysis. Treatment of UCM-derived MSCs, with 5-Azacytidine (5 μM) induced their differentiation into putative cardiac cells, as revealed by the expression of Cardiac-specific Troponin T (cTnT), smooth muscles actin (SMA), Myogenin (MYOG), Smoothelin (SMTN), and Cardiac α-actin (ACTC) genes and cTnT and α-actinin proteins by RT-PCR and immunocytochemistry, respectively. However, no beating cells were observed in differentiated MSCs. On the other hand, adult human foreskin-derived iPSCs could be successfully expanded and proliferated on MatrigelTM - coated aligned PCL nanofibrous matrices and was superior to SynthemaxTM - coated PCL nanofiber or tissue culture coated polystyrene (TCP) surfaces. The iPSCs cultured on MatrigelTM - coated aligned PCL nanofibrous matrices showed anisotropic behaviour along the PCL nanofibers and, upon differentiation, expressed cardiac-specific cTnT proteins and showed spontaneous beating. The beating CMs differentiated on MatrigelTM - coated PCL nanofibrous matrices showed significantly higher percentage of cTnT-positive CMs (23.34 vs. 32.55%) and showed more synchronized beating than those differentiated on MatrigelTM - coated TCP. Thus, electrospun aligned PCL nanofibers may be more suitable for proliferation and differentiation of stem cells into beating CMs than random PCL nanofibers or TCP. Results also suggest that the topology of PCL nanofibers, 5-Azacytidine treatment and collagen coating together contributes to the generation of cTnT and α-actinin positive aligned CMs from UCM-MSCs on aligned PCL nanofibers, which was not possible on TCPs. On the other hand, MatrigelTM supported for proliferation of iPSCs whereas PCL topology together with temporal modulation of Wnt signalling has contributed to their differentiation into beating CMs. Furthermore, the aligned PCL fibers not only increased the differentiation of iPSCs into CMs but also resulted in the alignment of the cells to resemble the anisotropic nature of CMs in native heart. In conclusion, the results of the present study suggest that plasticized PVA-PVP may be suitable for developing cardiac patches for CTE. On the other hand, electrospun, aligned PCL nanofibrous matrices, coated with MatrigelTM, may be useful for the development of cardiac tissue construct for culture and differentiation of stem cells into CMs for CT
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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