1,720,990 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
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
Distribution of baryonic and dark matter in spiral and irregular nearby galaxies
No full textMy PhD research is focused on the dark matter (DM) and luminous matter distribution in spiral and irregular galaxies. Studying this matter could clearly improve our knowledge on the formation and evolution of galaxies. While the overall description of the baryon content of galaxies is now well known, we will now use the kinematics to understand the distribution of DM, especially in the inner parts of galaxies. To do this, I study the distribution of the luminous and DM in nearby galaxies. The study consists of using the GHASP (Gassendi HAlpha survey of SPirals) sample which allows me to investigate the distribution of the DM halos in the inner regions of galaxies, by connecting the kinematical data from the optical observations to the photometry data available in the literature. After summarizing the global properties of the luminous and DM of galaxies, I present the instruments based on the FabryPerot interferomter used to observe the GHASP survey. I also present the different photometry (infrared and optical bands) data, and models used to determine the distribution of luminous and DM inside galaxies. In chapter 2, we present the kinematical data and the infrared photometry data available in the literature used to construct galaxy mass models. For the kinematical data, we use rotation curves from the GHASP survey. For the photometry data, we use the luminosity profile of the mid-infrared W1 and W2 (3.4 and 4.6 µm) of WISE (Wide-field Infrared Survey Explorer), which probes the emission from the old stellar population. The radial profile is decomposed if necessary to multiple components (bulge, disc, bar, spiral arm, ect.). Combining the optical kinematical data with the infrared photometry data allows us to determine the mass distribution of the sample of 121 galaxies covering morphological types from S0 to Irr, and therefore to understand how the DM halo is distributed in early type spiral compared to late type spiral and irregular galaxies. We use two main models to describe the shape of the DM halos in galaxies: the pseudo-isothermal core density profile and the Navarro-Frenk-White cuspy density profile. We allow the mass-to-light ratios of the disc and if necessary the bulge to vary and we keep them fixed by the colour (W1- W2). We also explore the maximum disc for the pseudo-isothermal model. We find that the two profiles describe well the rotations curves while the pseudo-isothermal model gives better results. In order, to understand how the DM is distributed, we study relations between the parameters of the DM and the luminosity of galaxies. We find that the relations between the DM halo parameters and the luminosity of galaxies depend on the morphological types (presence of bulge or not in galaxies). In chapter 3, we present the mass distribution of 100 early and late type spiral and irregular galaxies by combining the kinematical data (Hα rotation curves) with the optical Rc band photometry data available in the literature. We use the same methods and descriptions given in Chapter 2. The mass-to light ratios are now fixed using the (B - V) colour. We compare the results obtained using the optical Rc band photometry to the W1 band photometry. We find similar results on the DM halo parameters but the values are higher for the mass-to-light ratios in the Rc band than in the W1. However the dispersion in the model parameters is smaller and because stellar masses are better defined, the infrared photometry should be preferred, when possible, to the optical band. The Hi rotation curves are crucial in studying the distribution of the DM in the inner and outer regions of galaxies. In chapter 4, we first construct the mass distribution of 31 galaxies using the Hα rotation curves and mid-IR photometry data used in chapter 2 with the addition of the contribution from the Hi gas component. Secondly, the mass distribution is determined with the same photometry and gas component but using hybrid (Hα and Hi) extended rotation curves. Lastly, the mass distribution is constructed using Hi kinematical data. The main goal is to understand how the luminous and DM parameters may vary when using the different kinematical data. We use the same models to construct the mass models and the fitting procedures as described in chapter 2. We find that the relation between the parameters varies from one dataset to the other
Des Galaxies Proches Aux Galaxies Lointaines: Etudes Cinématique et Dynamique
No full textKinematical studies of low and high redshift galaxies enables to probe galaxy formation and evolution scenarios. Integral field spectroscopy is a powerful tool to study with accuracy nearby galaxies kinematics. Recent observations also gives a new 2D vision of high redshift galaxies kinematics. This work mostly relies on the kinematical sample of galaxies GHASP. This control sample, composed of 203 local spiral and irregular galaxies in low density environments observed with Fabry-Perot techniques in the Hα line (6563 Å), is by now the largest sample of Fabry-Perot data. After a revue on Fabry-Perot interferometry and a presentation of new data reduction procedures, my implications on both 3D-NTT Fabry-Perot instrument and the wide field spectrograph project (WFSpec) for galaxy evolution study with the european ELT are developed. The second section is dedicated to GHASP data. This sample have been fully reduced and analysed using new methods. The kinematical analysis of 2D kinematical maps has been undertaken with the study of the dark matter distribution, the rotation curves shape, bar signatures and the ionized gas velocity dispersion. In a third section, this local reference sample is used as a zero point for high redshift galaxies kinematical studies. The GHASP sample is projected at high redshift (z = 1.7) in order to disentangle evolution effects from distance biases in high redshift galaxies kinematical data observed with SINFONI, OSIRIS and GIRAFFE. The kinematical analysis of new SINFONI high redshift observations is also presented and high redshift data found in the literature are compared with GHASP projected sample, suggesting some evolution of the galaxy dynamical support within the ages.L'étude cinématique des galaxies locales et lointaines permet de contraindre les scénarios de formation et d'évolution des galaxies. Pour cela, la spectroscopie à champ intégral permet une étude détaillée de la cinématique des galaxies proches et fournit depuis peu des indices sur la cinématique des galaxies lointaines. Cette thèse s'appuie principalement sur l'utilisation de l'échantillon cinématique de galaxies locales GHASP. Cet échantillon de référence composé de 203 galaxies spirales et irrégulières de l'Univers local dans des environnements peu denses observées par interférométrie de Fabry-Perot autour de la raie Hα (6563 Å) est le plus grand échantillon de données Fabry-Perot à ce jour. Après un passage en revue des principes de l'interférométrie Fabry-Perot et des nouveautés apportées à la réduction des données Fabry-Perot, mon implication dans le développement du 3D-NTT, nouvel instrument utilisant deux Fabry-Perot est exposée de même que ma participation au projet de spectrographe à grand champ pour les ELT, WFSpec, dont l'objectif est l'étude de l'évolution des galaxies. Je présente dans une deuxième partie les données GHASP. Cet échantillon a été entièrement réduit et analysé à l'aide de nouvelles méthodes. L'analyse cinématique de l'échantillon à partir des cartes cinématiques 2D a été initiée en particulier avec l'étude de la distribution des halos de matière sombre, de la forme des courbes de rotation, de l'influence des potentiels barrés et de la dispersion de vitesses du gaz ionisé. Dans une troisième partie, cet échantillon local sert de point de référence pour l'étude de la cinématique des galaxies lointaines. L'échantillon GHASP est projeté à grand décalage spectral (z = 1.7) afin de déterminer les biais observationnels liés au manque de résolution spatiale des données cinématiques de galaxies lointaines obtenues par SINFONI, OSIRIS et GIRAFFE. L'analyse cinématique de nouvelles observations SINFONI y est également présentée, et l'ensemble des données cinématiques 2D de la littérature est mis en regard avec les résultats obtenus sur l'échantillon GHASP, mettant en évidence une évolution du support dynamique des galaxies avec le temps
Galaxy evolution in groups at intermediate redshift from the MUSE galaxies Groups In Cosmos survey
No full textInternational audienceMAGIC (Muse gAlaxy Groups In Cosmos) is a 100h MUSE-GTO survey aiming at understanding the impact of environment on galaxy evolution. It targets 15 massive groups at 0.3-z-0.8, identified in the zCOSMOS and VVDS VIMOS surveys, probing spatially resolved properties of galaxies down to low mass (\raisebox-0.5ex~10\⁸ Msun) but also the intra- group medium. After introducing MAGIC, I will present a first analysis of the ionised gas kinematic of galaxies in these groups which shows that the Tully-Fisher relation evolves due to quenching and contraction (Abril-Melgarejo+21). I will explain how MUSE observations led to the first detection of very extended ionised gas nebulae within groups, associated to processes such as tidal interactions, AGN feedback, shocks (Epinat+18) and ram pressure stripping (Boselli+19) at z\raisebox-0.5ex~0.7. I will conclude by discussing the implications of these results on galaxy evolution, on the quenching of starformation in dense environments and on the build-up of the Hubble sequence
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
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