1,720,956 research outputs found
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
Mesenchymal progenitor cells in human dental pulp: purification and characterisation
Get PDFINTRODUCTION:
Characterising the dental pulp perivascular cells will allow understanding whether these blood vessel associated cells have tissue regenerative potential that can be used for craniofacial regeneration, including bone, nerve, and tooth repair. Perivascular cells (pericytes and adventitial cells) can be purified from multiple human organs including placenta, bone marrow, pancreas, fat and muscle, and exhibit in culture and in vivo multilineage mesodermal developmental potential, implying the perivascular origin of the elusive, culture-derived mesenchymal stem cells (MSCs). Perivascular cells are ubiquitous in the organism and their developmental potential is partially imprinted by their tissue of origin. Pericytes in the dental pulp, which are deriving from primary or permanent teeth, originate from migrating cranial neural crest cells, which, theoretically, could exhibit superior potential to regenerate neural tissue. To test this, my aim was to characterise dental pulp cells and to evaluate their regenerative capacity.
MATERIAL AND METHODS:
To achieve this goal, we identified and isolated perivascular cells present in the human dental pulp. Dental pulp tissue was isolated from healthy third molar teeth from adults younger than 30 years old. Firstly, immunohistochemistry was performed to determine the presence of cell surface markers on dental pulp pericytes and adventitial cells using markers such as αSMA, PDGFRβ, LepR, CD107a, CD146, NG2 and CD34. Blood vessels were next characterised using MSC markers such as CD44, CD90, and CD29 and endothelial cell markers CD54, CD34, UEA-1, and vWF on pulp sections by immunofluorescence microscopy. Secondly, purification of dental pulp perivascular cells was performed using flow cytometry, followed by culturing and differentiation assays towards osteogenic, adipogenic and neurogenic cell lineages.
RESULTS:
We found that the phenotype of pericytes in the dental pulp in vivo is similar to that of pericytes in other human organs previously documented. They express CD146, ALP and PDGFRβ and lack endothelial cell markers such as CD34, vWF, CD54 or UEA-1. Importantly, we also found that pericytes are heterogeneous and can be further discriminated based on NG2, αSMA and LepR that coincide with a particular blood vessel type or blood vessel diameter. For example, αSMA is mainly expressed in microvascular pericytes and occasionally in capillaries, similar to LepR. NG2 is not expressed in venules but it is expressed in capillaries and arterioles. In contrast, MSC markers CD90, CD44, and CD29 were expressed on all pericytes suggesting that MSCs reside in heterogeneous perivascular niches.
Dental pulp mesenchymal stromal cells were next derived from CD146+CD34-CD56-CD45- pericytes or NG2+ and NG2- pericyte subsets and from CD146-CD34+CD56-CD45- adventitial cells, another perivascular cell source of MSCs located around large vessels. Our data show that, similar to MSCs, all perivascular cell subsets we purified were able to adhere to plastic dish, to expand in culture, and to efficiently accumulate calcium deposits upon osteogenic induction, reminiscent of bone development. However, most of cell lines tested were not adipogenic with the exception of rare cells in the NG2+ pericytes subset. Indeed, lipid droplets were consistently found accumulating only in these purified pericytes from 14 days onwards, albeit at a low frequency.
Finally, we discovered that, in situ, neural cells, positive for CD56 and vimentin, share markers with pericytes such as NG2 and CD146. We also found that in vitro, our perivascular cell-derived mesenchymal stromal cell lines express tubulin β III upon neuronal induction although these results require further confirmation.
CONCLUSIONS:
We documented the molecular signature of pericytes in the human dental pulp. We demonstrated that perivascular cell subsets can be prospectively purified to homogeneity and that perivascular cell-derived stromal cell cultures can be established in vitro. Intriguingly, our in vitro MSC functional assays showed that these cells are not multipotent, and thus are not genuine MSCs. They are, in contrast, very potent bone progenitors with a low frequency of arterial pericytes being adipogenic. Importantly, we here showed a marker overlap between neural cells and pericytes. Whether these cell types are developmentally linked remains to be established
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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