1,720,986 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
Modulating the activity of flavocytochrome b₅₅₈ : functional study
No full textLe complexe NADPH oxydase est un élément essentiel de l’immunité inné. Présent dans les cellules phagocytaires (neutrophile), sa fonction est de produire massivement, dans le phagosome, des anions superoxyde et générer ainsi des espèces encore plus réactives de l’oxygène qui vont détruire acides nucléiques, lipides et protéines des bactéries phagocytées. Le cœur membranaire catalytique du complexe NADPH oxydase est constitué d’un hétérodimère membranaire, le cytochrome b₅₅₈ (Cyt b₅₅₈). Après activation de celui-ci par les partenaires protéiques cytosoliques p47phox, p67phox, p40phox et Rac, une succession de réactions de transferts d’électron de part et d’autre de la membrane a lieu au sein du Cyt b₅₅₈ pour aboutir à la réduction du dioxygène de manière très contrôlée. Afin de mieux comprendre cette régulation, nous nous sommes d’abord intéressés aux stéreoisomères trans de l’acide arachidonique, activateur naturel de cet enzyme (cis), sur le fonctionnement de la NADPH oxydase et avons abordé cette étude parallèlement sur du Cytb₅₅₈ d’origine bovine présent dans des membranes de neutrophiles et dans des membranes de levures exprimant le Cytb₅₅₈ de manière hétérologue. Nous avons montré que la géométrie joue un rôle important sur l’activation du complexe enzymatique. Dans un deuxième temps, afin d’étudier le rôle de l’environnement membranaire sur le fonctionnement de la NADPH oxydase, nous avons déterminé les propriétés cinétiques et thermodynamiques de l’activité NADPH oxydase du Cytb₅₅₈ recombinant exprimé en levures, purifié, puis reconstitué en liposomes de composition lipidique variée. Après comparaison avec ces mêmes propriétés obtenues pour le Cytb₅₅₈ dans les membranes plasmiques et du réticulum endoplasmique de levures, nous avons montré que l’activité NADPH oxydase très sensible à la température peut être modulée par la composition et l’état physique de la membrane.NADPH oxidase complex is a major actor of both antimicrobial host defense and inflammation by generating highly regulated superoxide anion, rapidly converted into reactive oxygen species (ROS). The NADPH oxidase complex consists of a heterodimeric integral membrane flavocytochrome b₅₅₈ and three cytosolic components p67phox, p47phox and p40phox, and the small GTP binding protein Rac. In response to a cellular stimulus, cytosolic proteins are recruited to the phagosomal membrane where they are assembled with the Cytb₅₅₈ to form the active NADPH oxidase. The aim of the work was to better understand the modulation of superoxide anion production by this enzyme. For this purpose, we performed experiments with both bovine neutrophil membranes and yeast membranes expressing the bovine recombinant Cytb₅₅₈. We first investigated the effect of the trans-isomerization of the cis-arachidonic acid, the activator of NADPH oxidase in vitro and showed that specific geometry of the activator plays an important role in the activation of the complex. We also studied the role of the membrane environment on the functioning of NADPH oxidase and determined the kinetics and thermodynamics of NADPH oxidase activity depending on the lipid composition of Cytb₅₅₈ proteoliposomes. Comparison with these properties obtained with recombinant Cytb₅₅₈ embedded into endoplasmic reticulum and plasma membranes, we showed that the NADPH oxidase activity is highly temperature dependent and can be modulated by the lipid environment and the physic state of the membrane
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
Exploration of the p22phox/p47phox Interaction : A Key to Understand the Assembly of the NADPH Oxidase Complex
No full textLe complexe NADPH oxydase phagocytaire (NOX2), occupe une place cruciale dans la génération d'espèces réactives de l'oxygène, jouant un rôle essentiel dans l'immunité innée, ainsi que dans divers processus physiologiques, quant à sa dérégulation participe aux processus de stress oxydatif, du vieillissement ou de l'inflammation. Ce complexe enzymatique complexe est constitué de six sous-unités, dont deux sous unités membranaires, NOX2 et p22phox, tandis que les quatre autres sont des protéines cytosoliques (p47phox, p67phox, p40phox et Rac). NOX2 et p22phox, codés respectivement par les gènes CYBB et CYBA, forment le cœur catalytique du complexe NADPH oxydase des phagocytes. Ce cœur, également appelé flavocytochrome b558 (Cytb558), contient tous les intermédiaires rédox permettant les transferts d'électrons nécessaire à la réduction de l'oxygène en anions superoxyde. Malgré les défis persistants tel que la flexibilité du complexe, la compréhension de la structure et des fonctions de ces sous-unités est un domaine de recherche en croissance. La première étape de l'activation de l'enzyme nécessite l'interaction entre la protéine p47phox et la sous-unité membranaire p22phox. L’exploration de ces deux protéines, et qui plus est celle de leur interaction, sont rendues difficiles en raison des leurs propriétés intrinsèques (régions désordonnées, domaines membranaires, organisation en domaine d’une grande flexibilité). Bien que plusieurs études aient menées, Les mécanismes moléculaires mis en jeu restent à clarifier. Cette thèse se concentre sur plusieurs aspects de cette interaction en abordant cette problématique en combinant des techniques biochimies des protéines solubles et membranaires) avec des études par dichroïsme circulaire et par résonance magnétique nucléaire (RMN), des mesures de diffusion des rayons X aux petits angles (SAXS) et des prédictions de structure par intelligence artificielle (AlphaFold). Ces approches complémentaires ont permis de proposer un scénario montrant les changements conformationnels de p47phox de son état inactif vers des états actifs ont pu être démontrés. Ces changements de structure de p47phox ont par ailleurs été explorés dans le cadre de son interaction avec p22phox. Cela a révélé des aspects structuraux de cette interaction jusque-là méconnu. Parallèlement, l’intelligence artificielle au travers de l'outil AlphaFold a permis d’apporter pour la première fois des modèles structuraux du complexe enzymatique assemblé. Cela a permis d’explorer les interactions protéine-protéine et protéine-membrane lipidique qui devraient encourager des études futures plus approfondies. Enfin, la mise au point de la production et la purification de la protéine membranaire p22phox recombinante, notamment en nanodisques natifs, apporte à ce travail mixant approches expérimentales et théoriques des perspectives nouvelles.The phagocytic NADPH oxidase complex (NOX2) plays a pivotal role in generating reactive oxygen species, crucial for innate immunity and various physiological processes. Its dysregulation contributes to oxidative stress, aging, and inflammation. This complex enzyme comprises six subunits, including two membrane subunits, NOX2 and p22phox, and four cytosolic proteins (p47phox, p67phox, p40phox, and Rac). NOX2 and p22phox, encoded by the CYBB and CYBA genes, respectively, form the catalytic core of the phagocyte NADPH oxidase complex. This core, also known as flavocytochrome b558 (Cytb558), contains all redox intermediates for electron transfers needed to reduce oxygen to superoxide anions. Despite ongoing challenges like the complex's flexibility, understanding the structure and function of these subunits is an expanding research area. The enzyme's activation first requires the interaction between the p47phox protein and the p22phox membrane subunit. Investigating these proteins, particularly their interaction, is challenging due to their intrinsic properties, such as disordered regions, membrane domains, and highly flexible domain organization. Although several studies have been conducted, the molecular mechanisms involved remain to be clarified. This thesis focuses on several aspects of this interaction, addressing the issue by combining biochemical techniques (for both soluble and membrane proteins) with circular dichroism studies, nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), and structure predictions by artificial intelligence (AlphaFold). These complementary approaches have enabled the proposal of a scenario demonstrating the conformational changes of p47phox from its inactive state to active states. These structural changes of p47phox have also been explored in the context of its interaction with p22phox, revealing previously unknown structural aspects of this interaction. Concurrently, artificial intelligence through AlphaFold has provided the first structural models of the assembled enzyme complex, allowing exploration of protein-protein and protein-lipid membrane interactions, which should encourage more in-depth future studies. Finally, the development of production and purification methods for recombinant membrane protein p22phox, particularly in native nanodiscs, adds new perspectives to this work that blends experimental and theoretical approaches
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
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