387 research outputs found
Julien Devriendt (dir.), Jouer en bibliothèque
No full textQuestions de communication, N°30, p. 386-387.Recension de l'ouvrage : "Julien Devriendt, dir., Jouer en bibliothèque, Villeurbanne, Presses de l’Enssib, coll. La Boîte à outils, 2015, 176 pages.
Quelles leçons tirer des professionnels qui utilisent déjà les serious games ? – Table ronde (1)
No full textIntervention de Julien Devriendt, coordinateur des EPN et responsable multimédia de la médiathèque des Ulis lors de la journée thématique "Faites vos jeux ! Rien ne va plus ! Les serious games en bibliothèque" organisée à l\u27enssib, le 24 octobre 2012
2. « Comme si l’important dans l’écriture était le crayon utilisé »
No full textLongtemps engagé dans le développement des Fablabs en bibliothèque, Julien Devriendt poursuit son travail de transmission d’une culture numérique. Il prend ici la parole pour faire entendre sa voix de professionnel revenant sur un parcours au cours duquel il cherche à intégrer, toujours plus, le numérique au sein de pratiques existantes. Titulaire d’un brevet professionnel de la jeunesse, de l’éducation populaire et sportive TIC depuis dix ans, j’ai commencé en tant qu’animateur multimédia, o..
Valoriser et diffuser les arts numériques en bibliothèque : pratiques et enjeux. Villeurbanne : Presses de l’Enssib
No full texteditorial 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
Galaxy Modelling - II. Multi-Wavelength Faint Counts from a Semi-Analytic Model of Galaxy Formation
No full text(Abridged) This paper predicts self-consistent faint galaxy counts from the UV to the submm wavelength range. The STARDUST spectral energy distributions described in Devriendt et al. (1999) are embedded within the explicit cosmological framework of a simple semi-analytic model of galaxy formation and evolution. We build a class of models which capture the luminosity budget of the universe through faint galaxy counts and redshift distributions in the whole wavelength range spanned by our spectra. In contrast with a rather stable behaviour in the optical and even in the far-IR, the submm counts are dramatically sensitive to variations in the cosmological parameters and changes in the star formation history. Faint submm counts are more easily accommodated within an open universe with a low value of , or a flat universe with a non-zero cosmological constant. This study illustrates the implementation of multi-wavelength spectra into a semi-analytic model. In spite of its simplicity, it already provides fair fits of the current data of faint counts, and a physically motivated way of interpolating and extrapolating these data to other wavelengths and fainter flux levels
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
No full textLe 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)
Julien Devriendt, dir., Jouer en bibliothèque
No full textLa présence du jeu dans les bibliothèques est ancienne. Le développement des secteurs jeunesse dans les équipements de lecture publique dès les années 70 a contribué à donner une visibilité aux collections de jouets, de jeux de sociétés et jeux de plateaux… De plus, l’avènement du jeu vidéo comme pratique culturelle a conduit à accentuer cette diffusion. Aujourd’hui, les activités ludiques en bibliothèque donnent lieu à des démarches de médiation originales pour attirer de nouveaux publics se..
From seed to supermassive: simulating the origin, evolution and impact of massive black holes
No full textFirst 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
No full textMagnetic 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
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