1,720,958 research outputs found
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
Propriétés de diffusion des nanotubes de carbone dans des environnements tortueux et biologiques
No full textThe brain’s extracellular space (ECS) is a network of narrow clefts between neurons, glia, and blood vessels, accounting for about one-fifth of brain volume in healthy tissue. This fluid-filled compartment is essential for molecular transport, signalling, and homeostasis. It contains interstitial fluid (ISF) and a structural scaffold provided by the extracellular matrix (ECM). Despite decades of study, a full quantitative description remains elusive. Ensemble measurements of small-ion diffusion have shown that transport in the ECS is slowed two- to threefold compared to free solution. Yet such bulk approaches cannot pinpoint whether this hindrance arises from cellular geometry, ECM organisation, or transient molecular interactions.Single-particle tracking (SPT) offers a way to bridge this gap. By following fluorescent nanoparticles with nanometric precision and video-rate resolution, SPT exposes local heterogeneities invisible to ensemble averaging. A landmark study by Godin et al. introduced single-walled carbon nanotubes (SWCNTs) as near-infrared, photostable probes for SPT in brain tissue, showing that nanoscale trajectories could be recorded deep within scattering tissue. Later studies extended SPT to other tracers and experimental conditions, often contrasting control and pathology. While these provided valuable insights, they remained self-contained, leaving a patchwork of results—sometimes at odds with ensemble measurements and difficult to reconcile across probes.This thesis is motivated by filling this gap. By using novel ultra-short carbon nanotubes (uCCNTs) as tracers better matched to ECS dimensions, and combining them with three-dimensional tracking, it develops an experimental platform tailored to the nanoscale geometry of the ECS. Analytically, it adopts statistical tools from anomalous diffusion studies in membranes and cytoplasm, offering a more rigorous characterisation than conventional MSD fits. These methods allow the contributions of confinement, ECM organisation, and transient interactions to be disentangled.The results show that ECS diffusion is heterogeneous and often anomalous. At short timescales tracer motion is Brownian, but over longer intervals cellular boundaries drive a crossover to non-linear dynamics. Within this landscape, hyaluronan emerges as a key regulator: its depletion tightens local widths and hinders transport, underscoring its role as a buffer that preserves typical ECS dimensions. By integrating these insights, the thesis advances a unified view of extracellular transport that links single-trajectory statistics with structural determinants of the ECS.Beyond local transport, a key question is whether clearance from the ECS relies solely on diffusion or also involves active pathways. This distinction is central to understanding how the brain eliminates metabolites, aggregates, and therapeutic agents, with direct implications for the glymphatic system. To address this, we implemented gradient-index (GRIN) lens–based imaging for in-vivo single-particle tracking, extending nanoscale diffusion measurements from slices into the intact brain. This approach enables visualisation of tracer motion under conditions closer to physiology and provides a first step toward disentangling which mechanisms can drive clearance in the brain ECS.L’espace extracellulaire (ECS) du cerveau est un réseau de fins canaux interstitiels situé entre neurones, cellules gliales et vaisseaux, représentant environ un cinquième du volume cérébral. Rempli de fluide interstitiel et structuré par la matrice extracellulaire (ECM), il assure le transport moléculaire, la signalisation et l’homéostasie. Malgré des décennies d’étude, sa description quantitative reste incomplète. Les mesures d’ensemble de la diffusion d’ions ont montré un ralentissement de l’ordre de deux à trois fois par rapport à la diffusion dans de l’eau. Mais ces approches globales ne permettent pas d’identifier si ce freinage provient de la géométrie cellulaire, de l’organisation de la matrice ou d’interactions transitoires.Le suivi de particules uniques (SPT) apporte une réponse en révélant, avec une précision nanométrique, des hétérogénéités locales invisibles aux méthodes classiques. L’étude fondatrice de Godin et al. a introduit les nanotubes de carbone (SWCNTs) comme sondes photostables dans le proche infrarouge, montrant que des trajectoires nanoscopiques pouvaient être suivies au cœur du tissu cérébral. Depuis, le SPT a été appliqué à divers traceurs et modèles biologiques, souvent en comparant tissus sains et pathologiques. Ces travaux ont fourni des résultats précieux mais fragmentés, parfois contradictoires avec les mesures globales.Cette thèse s’inscrit dans ce contexte en développant une plateforme combinant nanotubes de carbone ultra-courts (uCCNTs), mieux adaptés aux dimensions de l’ECS, suivi tridimensionnel et outils analytiques issus de l’étude de la diffusion anormale. Cette approche permet de dépasser les simples comparaisons descriptives pour relier la structure de la matrice, le confinement géométrique et les interactions transitoires aux propriétés de diffusion mesurées.Les résultats montrent que la diffusion dans l’ECS est hétérogène et souvent anormale. Le mouvement est brownien à court terme mais devient non linéaire à plus longue échelle, sous l’effet des obstacles cellulaires. L’hyaluronane émerge comme un régulateur clé : sa déplétion resserre les canaux et freine le transport, soulignant son rôle de « tampon » qui maintient les dimensions typiques de l’ECS. Ces observations conduisent à une vision unifiée de l’ECS, non pas comme un milieu homogène, mais comme un réseau structuré où géométrie et matrice organisent ensemble le transport.Enfin, la question d’éventuelles voies actives dans le drainage cérébral reste ouverte. Pour l’aborder, nous avons développé une approche d’imagerie in vivo basée sur des lentilles à gradient d’indice (GRIN), permettant de suivre des particules uniques dans le cerveau intact, dans des conditions plus proches de la physiologie. Cette méthode constitue une première étape vers l’identification des mécanismes qui gouvernent le drainage des métabolites, agrégats pathologiques et agents thérapeutiques, au cœur du débat sur l’existence d’un système glymphatique dans le cerveau
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
- …
