1,720,959 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
Analysis of gating of Acid-Sensing Ion Channels (ASICs)
No full textLes cellules neuronales, qui sont les unités composant le système nerveux, peuvent « sentir » tous les changements du milieu qui se passe soit à l'interne ou aussi à l'externe de la cellule. Un neurone se sert d'un riche répertoire de « senseurs », ou récepteurs, pour percevoir tous ces changements. De plus ce qui est incroyable, c'est que chaqu'un de ces récepteurs est spécialisé à détecter un type de changement seulement. Par exemple, un neurone aura des récepteurs spécifiques pour détecter des changements du taux de CO2 dans le sang, d'autres pour détecter le niveau de sucre ou la quantité de neurotransmetteurs et d'autres, appelé ASICs, pour sentir des acidifications extracellulaires. Pourquoi les neurones ont ces ASICs pour sentir ces acidifications ? Pendant un accident vasculaire cérébral (AVC) ischémique, notre cerveau devient comme un citron. Des acidifications lentes s'établent et ces ASICs sont donc très sollicités sous ces conditions et peuvent causer la mort des neurones. Mais si bien contrôlé, une acidité peut aussi être bénéfique et agir comme un neurotransmetteur et donc promouvoir la communication neuronale via les ASICs. La majorité des scientifiques a étudié ces ASICs suite à des acidifications rapides. C'est donc indispensable de connaitre comment ces ASICs se comportent suite à des acidifications de nature plus lentes associés aux genres d'acidifications qu'on a dans nos cerveaux. J'ai donc d'abord établit un modèle informatique pour simuler le comportement de ces ASICs suite aux acidifications lentes. Par les expériences, j'ai confirmé les prédictions des simulations en observant que les neurones sont beaucoup plus sollicités lors des acidifications lentes plutôt que des acidifications rapides. De plus, lorsque les changements de pH étaient accompagnées de changements de milieu qui simulaient les conditions de milieu lors de fortes communications neuronales, ces acidifications lentes stimulaient encore plus les neurones. Le comportement des ASICs s'avéré être prédit par le modèle informatique, qui pourra donc constituer un outil pour prédire la réponse d'ASICs en conditions plus physiologiques. Dans un autre projet, plutôt pharmacologique, j'ai améliorée certains modulateurs d'ASICs en découvrant des composés plus puissants. J'ai découvert des composés qui bloquent la réponse d'ASICs. Ils pourront donc être bénéfiques pour réduire les conséquences d'un AVC. J'ai découvert aussi des composés particuliers qui potentialisent l'activité d'ASICs. Ils pourront alors promouvoir la communication neuronale et améliorer nos performances cognitives.
--
L'acidité est généralement associée à la douleur, spécialement dans le système nerveux périphérique (SNP). Dans le système nerveux central (SNC), au contraire, elle peut promouvoir la communication neuronale. Les neurones ont plusieurs types de senseurs d'acidité, entre autres les « acid-sensing ion channels » (ASICs). Ils sont des canaux ioniques qui s'ouvrent de façon transitoire en réponse à une acidification extracellulaire pour permettre au sodium d'entrer dans le neurone et induire des potentiels d'actions. Le comportement des ASICs en réponse au pH peut être décrit avec trois états de conformation différents : l'état fermé, ouvert et désensibilisé. Les transitions cinétiques reliant ces trois états composent le modèle cinétique des ASICs, qui au début de ma thèse n'avait pas été établit. En utilisant des techniques d'électrophysiologie, j'ai décrit le modèle cinétique d'ASICla et -3, qui sont respectivement des sous-unités exprimé dans le SNC et SNP. Avec les données récoltées j'ai construit un modèle computationnel pour prédire la réponse d'ASIC au changement de pH et aux vitesses de ces changements. J'ai modelé et confirmé expérimentalement avec succès le comportement des ASICs suite à un changement rapide ou lent de pH, qui sont des événements pouvant se dérouler dans notre cerveau en condition normale ou lors d'une ischémie cérébrale, et au niveau du SNP pendant une inflammation. Il est attendu qu'une acidification rapide ouvre les ASICs, tandis qu'une acidification lente les désensibilise. Cependant, j'ai observé que, une acidification lente peut ouvrir les ASICs et générer des petits courants. J'ai modelé la réponse neuronale à ces petits courants et montré expérimentalement qu'elles peuvent engendrer plus de potentiels d'actions et accroitre l'excitabilité neuronale par rapport aux grands courants issus des acidifications rapides. Finalement j'ai montré que ASICla est nécessaire pour moduler l'excitation neuronale en réponse à des changements ioniques, outre que le pH, qui ont heu pendant une haute activité de transmission nerveuse. Le deuxième projet de ma thèse s'est basé sur la découverte d'une molécule appelé 2- guanidine-4-methylquinazoline (GMQ), qui pouvait moduler ASICla et -3. Malgré des propriétés intéressantes, GMQ ne montre qu'une faible spécificité et puissance. Nous avons alors instauré une collaboration avec un chimiste afin de faire un screening sur ASICla et -3 avec la technique d'électrophysiologie pour tester différents composés dérivant du GMQ. J'ai donc trouvé des toutes nouvelles molécules actives sur ASICla et -3, montrant une puissance plus élevée et une meilleure spécificité entre les deux sous-unités. J'ai finalement identifié la première molécule chimique qui a le pouvoir de potentialiser le courant d'ASICla. La potentialisation pharmacologique d'ASICla pourrait aboutir à des performances accrues de la communication neuronale et améliorer les fonctions cognitives.
--
Acidity is often associated with pain, especially when we consider the peripheral nervous system (PNS). On the other hand, protons participate in neuronal communication in the central nervous system (CNS). Neurons have différent types of acid sensors. Among these sensors are the acid-sensing ion channels (ASICs). These channels open transiently in response to extracellular acidifications and allow sodium entering the cell. This entry of sodium causes depolarizations in neurons and eventually induces action potentials. The ASIC behavior in response to pH can be described by the transitions between three main conformational states of these channels: the closed, the open and the desensitized state. The gating transitions describe how the ASICs switch from one state to another as a fonction of the pH and time. The gating transitions connect the three conformational states and compose the so-called ASIC kinetic scheme, which at the beginning of my thesis was still poorly defined. Using patch-clamp electrophysiology I measured the transition rates of the kinetic scheme of ASIC la and -3 isoforms that are highly expressed in the CNS and PNS respectively. With the collected data I built a computational model that I used to predict the behavior of ASICs in response to any extent of pH changes and also to any speed by how these pH changes occur. I modeled and successfully confirmed by mean of experiments the ASIC behavior in response to rapid and slow acidification. Slow acidifications can occur in vivo in our brain under normal condition, during an ischemic stroke and neuronal inflammation. Rapid acidifications promote the opening of ASICs, while slow acidifications are thought to rather promote desensitization. However, I showed that a slow pH change can resuit in ASIC opening and generate small currents. I modeled the neuronal response to these small currents and showed then experimentally that they can induce higher neuronal excitation than the higher currents of rapid acidifications. Finally, I showed that ASIC la is necessary to mediate neuronal excitation in response to ion changes, other than pH, normally occurring with high neurotransmission activity. The second project of my thesis was based on the discovery of a small molecule called 2-guanidine-4-methylquinazoline (GMQ) that has been identified to modulate ASIC la and ASIC3. Despite interesting properties on ASICs gating, GMQ présents low specificity and low potency. Therefore, in collaboration with a chemist, we started a screening of GMQ-derivatives by patch-clamp electrophysiology and identified new compounds active on ASIC la and -3 that show higher specificity among the two isoforms, and higher potency. I also identified the first known chemical that enhances ASIC la currents. The pharmacological ASIC la potentiation may enhance neuronal communication and improve cognitive function
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
- …
