1,720,969 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
Laser micro-patterning of dental zirconia: effects on microstructure and reliability
Get PDFVersió amb diverses seccions retallades, per drets de l'editorTetragonal polycrystalline zirconia stabilized with 3% mol of yttria (3Y-TZP) is a popular bioceramic, increasingly used for dental applications thanks to its good mechanical properties, biocompatibility and aesthetic outcome. The addition of stabilizers oxides retains the metastable tetragonal structure, which can transform to the stable monoclinic form upon mechanical or chemical solicitation with its associated volume increment. If the phase transformation is induced by high stresses at the tip of an advancing crack, transformation toughening mechanisms are activated hindering further propagation of the crack and making this material more tough and damage tolerant. On the other hand, when 3Y-TZP is exposed to humid environment at moderate temperatures water species diffuse inside the tetragonal lattice triggering progressive phase transformation and the consequent degradation of the surface. This is known as low temperature degradation (LTD), hydrothermal degradation or aging and is one of the main drawbacks of this family of materials, especially for biomedical applications.
There has been a growing interest in modifying the surface topography in order to influence the biological response to these biomaterials. Among the available methods, laser patterning is one of the most promising because it is a non-contact and therefore not-contaminating technique and it allows great precision. In particular, Direct Laser Interference Patterning (DLIP) allows patterning at the micrometric- and nanometric-scale in a single-step process. Laser beams interference creates a periodical distribution of intensity that produces the desired pattern on the surface. It has been successfully applied on metals, polymers and ceramics for different applications spanning from antimicrobial coatings to tribological applications. Its application to 3Y-TZP seems therefore promising but needs a thorough characterization in order to ensure the short and long term stability.
This work contributes to understand how nanosecond laser interference patterning modifies the topography and microstructure of 3Y-TZP and how these changes influence the integrity and reliability of the material after the laser treatment. DLIP in the nanosecond regime is a suitable technique to introduce periodical topography at the micrometric scale on the surface of 3Y-TZP. Laser-material interaction mainly results in thermal effects, producing the desired topography alteration thanks to material melting and liquid flow. Pattern geometry and overall surface roughness can be modified independently varying laser fluence and number of pulses. The surface treatment is not free of collateral damage due to thermal shock. Microcracking, recrystallization, residual stresses, phase transformation and texturization are produced on the treated surface. These microstructural modifications are concentrated in a thin layer of material (1 µm thick) and are not a concern for mechanical integrity of the treated material. However, pre-existing defects on the surface can interact with the laser beam, becoming larger critical defects that lower the overall mechanical resistance. Therefore, a good surface finish, ideally free of defects, would ensure an optimal outcome of the surface treatment. Finally, the LTD resistance is reduced by the laser treatment because of the monoclinic phase and residual stresses induced by thermal shock. An annealing treatment is capable of restoring the LTD resistance, even more than before the laser treatment thanks to the texture induced in the tetragonal phase.
Therefore, to ensure the good outcome of such laser patterning on 3Y-TZP a thermal treatment (at 1200°C for 1 hour) is recommended to ensure the long term reliability and a defect-free surface is recommendrecommended to ensure the long term reliability and a defect-free surface is advisable to reduce the detrimental effect of laser on mechanical properties.La circona poli-cristalina estabilizada con el 3% mol de yttria (3YTZP) es un material cerámico comúnmente utilizado en aplicaciones biomédicas y prótesis dentales gracias a sus buenas propiedades mecánicas, su biocompatibilidad y estética. La incorporación de óxidos estabilizantes permite retener la fase tetragonal de manera meta estable, tal que se pueda
trasformar en fase monoclínica por acción mecánica o química y aumentar consecuentemente de volumen. Si la transformación de fase es inducida por las tensiones en la punta de una grieta que avanza, se activa el mecanismo de tenacizacion por trasformación impidiendo una mayor propagación de la grieta y haciendo que este material sea más tenaz y tolerante al daño. Por otro lado, cuando se expone la 3Y-TZP a ambientes húmedos a temperaturas
moderadas, las moléculas de agua difunden dentro de la red tetragonal, lo que desencadena una transformación de fase progresiva y la consecuente degradación de la superficie. Esto se conoce como degradación a baja temperatura (Low Temperature Degradation, LTD), degradación hidrotermal o envejecimiento y es uno de los principales inconvenientes de esta familia de materiales, especialmente para aplicaciones biomédicas.
Hay un interés creciente en modificar la topografía de la superficie con el fin de influir en la respuesta biológica de estos biomateriales. Entre los métodos disponibles, el patrón de láser es uno de los más prometedores, ya que es una técnica sin contacto y, por lo tanto, no contaminante y permite una gran precisión. En particular, el Patrón Láser Directo por Interferencia (Direct Laser Interference Patterning, DLIP) permite el modelado a escala
micrométrica y nanométrica en un solo paso. La interferencia de rayos láser crea una distribución periódica de intensidad que produce el patrón deseado en la superficie. Esa técnica se ha aplicado con éxito en metales, polímeros y cerámicas con diferentes aplicaciones que abarcan desde revestimientos antimicrobianos hasta aplicaciones tribológicas. Su aplicación a la 3Y-TZP parece prometedora, pero necesita una caracterización exhaustiva para
garantizar la estabilidad a corto y largo plazo del material tratado.
Este trabajo contribuye a comprender cómo el DLIP de nanosegundos modifica la topografía y la microestructura de 3Y-TZP y cómo estos cambios influyen en la integridad y fiabilidad del material después del tratamiento con láser. Se ha prestado especial atención a la resistencia a la degradación hidrotermal de esta familia de materiales después del patrón del láser, debido a su susceptibilidad a los cambios microestructurales causados por los tratamientos de superficie. El DLIP de nanosegundos es una técnica adecuada para introducir una topografía periódica a escala micrométrica en la superficie de 3Y-TZP.
La interacción del láser con el material produce principalmente efectos térmicos, creando la alteración de topografía deseada gracias a la fusión del material y al flujo de material líquido. La geometría del patrón y la rugosidad de la superficie se pueden modificar de forma independiente variando la fluencia del láser y el número de pulsos. El tratamiento de superficie no está libre de daños colaterales debido al choque térmico. Se producen microagrietamento, recristalización, tensiones residuales, transformación de fase y texturización en la superficie tratada. Estas modificaciones microestructurales se concentran en una capa superficial de
material (1 μm de espesor) y no afectan la integridad mecánica del material tratado. Sin embargo, los defectos preexistentes en la superficie pueden interactuar con el rayo láser, convirtiéndose en defectos críticos más grandes que disminuyen la resistencia mecánica general. Por lo tanto, un buen acabado superficial, idealmente libre de defectos, garantizaría un resultado óptimo del tratamiento superficial. Finalmente, la resistencia a la degradación hidrotermal se reduce mediante el tratamiento con láser debido a la fase monoclínica y las tensiones residuales inducidas por el choque térmico. Un tratamiento de recocido es capaz de restablecer la resistencia a la degradación hidrotermal, incluso mayor que la de antes del tratamiento con láser, gracias a la textura inducida en la fase tetragonal.
Por lo tanto, para garantizar el buen resultado de dicho patrón láser en 3Y-TZP, se recomienda un tratamiento térmico (a 1200 ° C durante 1 hora) para garantizar la fiabilidad a largo plazo y un acabado superficial libre de defectos superficiales es aconsejable para reducir el efecto
perjudicial del láser en propiedades mecánicasPostprint (published version
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
- …
