1,721,040 research outputs found
Mediation of Osteoblast Responses to Titanium Roughness by Adsorbed Proteins
No full textStable fixation of implants such as artificial teeth depends on the direct apposition of bone to the implanted material. While endosseous implants were traditionally allowed to "osseointegrate" over several months without carrying load, clinical and experimental data show that prostheses with roughened surfaces allow successful integration when subject to earlier loading and more challenging implant sites. However, to design implant surfaces for an optimal biological response requires an understanding of the mechanism by which roughened surfaces promote osseointegration. Research into this mechanism has, to date, focussed primarily on the response of osteoblastic cells to surface topography in vitro. While these have demonstrated some consistent trends in cell behaviour, the fundamental means by which cells sense and respond to roughness remain unclear. It has been suggested that cell responses to changes in topography may relate to differences in the proteins adsorbed from serum (in vitro). While experimental evidence indirectly suggests that physical features can affect protein adsorption, few studies have examined this with respect to surface roughness, particularly as a mediator of cell responses. To address this issue, cell culture and protein adsorption experiments were\ud
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conducted on a limited range of surface textures. Titanium samples were ground to\ud
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produce morphologically similar surfaces with three grades of roughness. A duplicate set of specimens were heated at 600°C for one hour, with the aim of masking potential variations in physicochemical properties with differing degrees of grinding. Osteoblast attachment and proliferation studies were conducted over a short time-frame of 48 hours or less, to highlight the effects of proteins adsorbed from serum rather than secreted by adherent cells. Gel electrophoresis provided a profile of the proteins adsorbed to each surface after 15 minutes, corresponding to the time by which the cells had settled onto the surface. Finally, confocal microscopy was used to examine cell morphology on each surface, and to visualize specific interactions between cellular structures and adsorbed adhesion-mediating proteins. Although the effects were inconsistent, attachment assays showed some indications that fewer cells attached in the first 90 minutes as roughness increased. This inverse cell number-roughness trend was significant at 48 hours; however, the variability in attachment assays prevented reliable separation of attachment and proliferation rate effects. While the reduction in cell number with increasing roughness is consistent with previous reports, it is typically observed at later time points, and thus may be increasingly confounded by contact inhibition and differentiation. Thermal oxidation of the titanium did not impact on osteoblast responses to roughness, although it significantly slowed cell proliferation. The latter result was unexpected on the basis of previous reports. One-dimensional gel electrophoresis revealed no significant differences in the composition of adsorbed layers with variations in roughness. However, as expected on account of wettability changes, the heat-treatment did correspond to significant changes in the adsorption profile. While this was not a highly sensitive analysis, it suggests that the cell responses to roughness changes were not governed by broadscale differences in the proteins initially available to adhering cells. In addition to the composition of the adsorbed layer, the distribution of proteins may also vary with topography. The immunofluorescence methods were not sufficiently sensitive to reveal the distribution of adsorbed adhesion proteins (vitronectin and fibronectin). However, the lack of clear labelling does suggest an absence of large accumulations due to specific topographic features. Further work is required to address this issue conclusively. Observations of cell morphology were consistent with widely-reported contact guidance phenomena on grooved surfaces, with elongation and alignment (with topography) increasing with groove depth. Cell elongation was also enhanced on the more hydrophilic, heat-treated titanium, but this effect diminished over time. Although increased elongation at 90 minutes corresponded to lower cell numbers at 48 hours, no causal relationship has yet been established
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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