1,721,245 research outputs found
Valoriser et diffuser les arts numériques en bibliothèque : pratiques et enjeux. Villeurbanne : Presses de l’Enssib
Full text linkeditorial reviewedCompte rendu de l'ouvrage "Valoriser et diffuser les arts numériques en bibliothèque. Pratiques et enjeux", coordiné par Devriendt Julien aux presses de l'ENSSIB
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
Valoriser et diffuser les arts numériques en bibliothèque
No full textAccueillir et diffuser les œuvres de la création contemporaine numérique, sous toutes ses formes, permet de repenser la bibliothèque. Fablabs artistiques, jeux vidéo, festivals, hackathons et « malles à pixels »… les expériences exposées au fil du livre concernent tous les publics et toutes les bibliothèques. Comment faire du soutien à la création numérique un axe fort de son projet d’établissement ? Qui sont les artistes numériques ? Comment se former, découvrir les nouvelles formes de narration à l’œuvre ? L’ouvrage apporte des réponses concrètes, et propose un panorama des acteurs, des lieux et des événements dédiés à l’art numérique
Jouer en bibliothèque
Full text linkLe développement du jeu vidéo mais également l’engouement des jeunes adultes pour les jeux de plateau, l’utilisation de dispositifs ludiques comme outils de médiation ou associés aux apprentissages sont venus prolonger les services des ludothèques et conduisent les bibliothèques à se réinventer pour devenir les lieux naturels où permettre la pratique de l’expérience du jeu dans toutes ses dimensions. Le plan s’organise autour de quatre parties : connaître le contexte (les espaces, les équipes, le droit), acquérir/valoriser (les fonds, jouets et serious games), animer/créer (projet de service, partenariats, médiation), et participer (une approche orientée communauté)
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
From seed to supermassive: simulating the origin, evolution and impact of massive black holes
Full text linkFirst observed as early as redshift z = 7 and now thought to be found at the centre of every massive galaxy in the local Universe, the evolution history of supermassive black holes (SMBHs) spans over 13 billion years. In this thesis, the coevolution between SMBHs and their host galaxies is studied using a set of hydrodynamical simulations to isolate different components of the interaction between black holes and cosmic gas. The simulations range from black hole accretion in an idealised context to the impact of feedback in the cosmological simulations of the HORIZON suite.
The origin of SMBHs during the first billion years of the Universe is a highly non-linear problem, where small-scale behaviour influences large- scale behaviour and vice versa. Gas fuelling a black hole flows from the cosmic web, through its host galaxy and into the black holeâs gravitational potential, before eventually reaching its event horizon. Even discounting the complex physical processes at play, resolving the 19 orders of magni- tude in spatial scale involved is beyond the capabilities of current simula- tions. Some of the length scales therefore have to be covered by sub-grid algorithms which need to be able to handle a wide range of environments.
Idealised accretion simulations presented in this thesis show that the Bondi-Hoyle-Lyttleton (BHL) accretion algorithm is sufficiently versatile. It automatically determines the accretion rate onto the black hole by the mass flux into its accretion region when the black holeâs gravitational po- tential becomes resolved. The accretion rate onto the black hole therefore naturally converges to the correct solution once the size of the accretion region approaches the physical size of the black hole. A drag force algo- rithm that compensates for unresolved dynamical friction, on the other hand, produces a force on the black hole that can unphysically accelerate it relative to the bulk flow of the gas. It needs to be switched off when gas properties are measured within the black holeâs gravitational potential.
A study of black hole accretion within an isolated cooling halo confirms that the accretion algorithm is able to handle the flow configurations en- countered within an evolving galaxy. To ensure gas is always accreted within the black hole's gravitational potential, a refinement algorithm called "zoom-within-zoom" is introduced in this thesis. It allows the black hole environment to be resolved by orders of magnitude above that of its host galaxy. A low mass seed black hole with a strong drag force early on takes advantage of this extra information during the black holeâs early evolution. In the longer term, resolving gas clouds in the black hole vicin- ity to sub-pc scales has a lasting impact on both the mass evolution and duty cycle of massive black holes.
Sub-pc size clumps also play a deciding role in the first 200 Myr of evo- lution of a SMBH progenitor in a full cosmological context: 90% of its mass is gained through interactions with dense clumps, which fuel super- Eddington accretion bursts. Once the gas within the host galaxy settles into a rotationally supported disc, star formation and black hole accre- tion slow down. As both primarily occur within the central 30 pc of the compact host galaxy, star formation in proto-galaxies has a major impact on black hole accretion even in the absence of feedback.
At low redshift, on the other hand, feedback becomes the crucial link between a SMBH and its host galaxy. A comparison of two simulations from the HORIZON suite, run with and without active galactic nuclei (AGN) feedback respectively, shows that AGN feedback is able to prevent as much as 90% of the stellar mass from forming in the most massive galaxies. Quenching proceeds via a combination of AGN driven outflows and reduced inflows and evolves with redshift as the MSMBH â M* relation flattens from z = 5 to z = 0.
In conclusion, neither the evolution of galaxies nor that of black holes can be understood without the context of the other. At high redshift, the competition between star formation and black hole accretion inside the compact host galaxy intrinsically links the origin of SMBHs to the early evolution of galaxies. At low redshift, AGN feedback modulates the gas supply of the host galaxy, which has a lasting impact on star formation. The coevolution of black holes and galaxies therefore spans their entire history.</p
Magnetic fields in and around galaxies
Full text linkMagnetic fields are an ubiquitous component of our Universe. They are expected to play an important role in the evolution of many astrophysical systems, from molecular clouds to galaxy clusters. In the case of galaxies, magnetic energy is measured to be in equipartition with thermal and turbulent energies of the interstellar medium. Despite this omnipresence, the origin of cosmic magnetic fields remains an open question, and the precise influence that magnetic fields have in shaping the formation and evolution of galaxies is uncertain.
Using magnetohydrodynamical numerical simulations of both cosmological volumes and high-resolution cosmic zoom-ins on individual galaxies, I explore in this thesis the main mechanisms likely to generate galactic magnetic fields similar to those observed and the role these latter play in shaping galaxies. I present various extensions to existing numerical techniques to account for magnetism in state-of-the-art software employed to simulate galaxies. These culminate in the introduction of a new algorithm that traces magnetic fields generated by different sources separately. In particular, I simulate the formation of a Milky Way-like galaxy, magnetised either through dynamo amplification, a strong primordial magnetic field, or magnetised stellar feedback, demonstrating that each mechanism is capable of producing realistic levels of magnetisation on its own. Jointly tracing primordial and stellar generated fields, I study how they compete to produce the total magnetic field. I find a large degree of interaction, both inside galaxies, where the two components contribute significantly to the magnetic energy budget, and around galaxies, where the magnetic fields pushed out by stellar feedback pollute the primordial magnetic field. In a final set of simulations, I explore how magnetic fields modify the global properties of a galaxy, finding evidence of morphological compression and braking of the rotation of the galaxy by strong magnetisation.</p
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
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