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See detailLes interférences analytiques : les anticorps hétérophiles
Cavalier, Etienne ULg

Conference given outside the academic context (2006)

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See detailLes interférences analytiques dans les dosages immunologiques
Cavalier, Etienne ULg

Conference given outside the academic context (2006)

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See detailLes interférences entre le divorce et les pensions de retraite et de survie: le point de la question
Michiels, Olivier ULg

in Divorce : Actualité Juridique, Sociale et Fiscale (2002), 7

L'article examine les conséquences du divorce sur le droit à la pension de retraite et à la pension de survie.

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See detailInterférences entre phonologie et syntaxe en pathologie développementale du langage
Parisse, Christophe; Maillart, Christelle ULg

in Langage et l'Homme (Le) : Recherches Pluridisciplinaires sur le Langage (2006), 41

We compare three theories (pure phonological theory, surface theory, and mapping theory) about language developmental disorders considering that phonological difficulties are the main reason for the ... [more ▼]

We compare three theories (pure phonological theory, surface theory, and mapping theory) about language developmental disorders considering that phonological difficulties are the main reason for the children’s disorders. First, we identified the linguistic parameters (salience, phonological complexity, syntactic complexity, lexical/functional, semantic/syntactic) that are fundamental to these theories. Then we tested the validity of these parameters by testing them against results obtained by SLI children and control children. Nine syntactic categories were tested (determiner, noun, verb, etc.) No theory could fully explain the results obtained. Some linguistic parameters (eg. phonological complexity) are very interesting but fail to explain all results. Some other parameters (eg. salience) turned out to be inadequate to explain the results of French-speaking children. [less ▲]

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See detailInterferogram Stitching applied to the surface metrology of millimeter–wave and micrometer-wave reflectors
Roose, Stéphane ULg

in Slangen, Pierre; Cerruti, Christine (Eds.) Proc. SPIE 6341, Speckle06: Speckles, From Grains to Flowers (2006, September)

This paper addresses the interferometric measurements performed on PLANCK Secondary reflector-Flight Model (SRFM) during the cryo-optical test at the Centre Spatial de Liege in Belgium. It was requested ... [more ▼]

This paper addresses the interferometric measurements performed on PLANCK Secondary reflector-Flight Model (SRFM) during the cryo-optical test at the Centre Spatial de Liege in Belgium. It was requested to measure the changes of the surface figure error (SFE) with respect to the best ellipsoid, between 293 K and 50 K, with a 1 μm RMS accuracy. To achieve this, Infra Red interferometry has been selected and a dedicated thermo mechanical set-up has been constructed. One emphasizes on the solutions adopted to cope with high surface slopes appearing at cryogenic temperature. Indeed, detector resolution has been exploited to resolve high density fringes at the expense of the aperture. A stitching procedure has been implemented to reconstruct the full aperture measurement with success. Test results are presented. [less ▲]

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See detailAn interferometric camera : ESPI and Photorefractivity
Deveuster, Christophe; Georges, Marc ULg

Conference (1998, May 12)

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See detailInterferometric Constraints on Gravity Darkening with Application to the Modeling of Spica A & B
Aufdenberg, J. P.; Ireland, M. J.; Mérand, A. et al

in Hartkopf, W. I.; Guinan, E. F.; Harmanec, P. (Eds.) Binary Stars as Critical Tools & Tests in Contemporary Astrophysics (2007, August 01)

In 2005 we obtained very precise interferometric measurements of the pole-on rapid rotator Vega (A0 V) with the longest baselines of the Center for High Angular Angular Resolution (CHARA) Array and the ... [more ▼]

In 2005 we obtained very precise interferometric measurements of the pole-on rapid rotator Vega (A0 V) with the longest baselines of the Center for High Angular Angular Resolution (CHARA) Array and the Fiber Linked Unit for Optical Recombination (FLUOR). For the analysis of these data, we developed a code for mapping sophisticated PHOENIX model atmospheres on to the surface of rotationally distorted stars described by a Roche-von Zeipel formalism. Given a setof input parameters for a star or binary pair, this code predicts the interferometric visibility, spectral energy distribution and high-resolution line spectrum expected for the system. For the gravity-darkened Vega, our model provides a very good match to the K-band interferometric data, a good match to the spectral energy distribution -- except below 160 nm -- and a rather poor match to weak lines in the high dispersion spectrum where the model appears overly gravity darkened. In 2006, we used the CHARA Array and FLUOR to obtain high precision measurements of the massive, non-eclipsing, double-line spectroscopic binary Spica, a 4-day period system where both components are gravity darkened rapid rotators. These data supplement recent data obtained with the Sydney University Stellar Interferometer. Our study follows the classic 1971 study by Herbison-Evans et al. who resolved Spica as a binary with the Narrabri Intensity Interferometer. We will report on our progress modelling the new interferometric and archival spectroscopic data, with the goal towards better constraining the apsidal constant. [less ▲]

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See detailInterferometric fringes projection system for 3D profilometry and relief investigation
Moreau, Vincent; Laboury, Dimitri ULg; Tilkens, Bernard et al

in Optical Methods for Arts and Archaeology, Proceedings of SPIE, Vol. 5857 (2005)

We present a new 3D full-frame profilometer based on structured laser light projection method. This device takes advantage of the polarization states splitting technique for producing and shifting ... [more ▼]

We present a new 3D full-frame profilometer based on structured laser light projection method. This device takes advantage of the polarization states splitting technique for producing and shifting multiple sinusoidal Young’s interference patterns that are projected on the inspected surface. The principle of the technique is presented and we discuss the advantages of monochromatic light projection method as a mean to overcome ambient lighting for in-situ measurement. Some results that we obtained on objects from the Egyptian Department of the British Museum are presented to demonstrate that 3D laser profilometry is a worthwhile technique for epigraphic investigations where naked-eye inspections fail. [less ▲]

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See detailInterferometric Gravity Darkening Observations of Vega with the CHARA Array
Aufdenberg, J. P.; Merand, A.; Coude Foresto, V. et al

in Coudé du Foresto, V; Rouan, D; Rousset, G (Eds.) Visions for Infrared Astronomy (2006, March)

We have obtained high-precision interferometric measurements of the A0 V standard star Vega with the Center for High Angular Resolution Astronomy (CHARA) Array and the Fiber Linked Unit for Optical ... [more ▼]

We have obtained high-precision interferometric measurements of the A0 V standard star Vega with the Center for High Angular Resolution Astronomy (CHARA) Array and the Fiber Linked Unit for Optical Recombination (FLUOR) beam combiner in the K' band at projected baselines between 103 m and 273 m. The measured squared visibility amplitudes beyond the first lobe are significantly weaker than expected for a slowly rotating star and provide strong evidence for the model of Vega as a rapidly rotating star viewed very nearly pole on. We have constructed a Roche-von Zeipel gravity-darkened model atmosphere which is in generally good agreement with both our interferometric data and archival spectrophotometry. Our model indicates Vega is rotating at Ë 92% of its angular break-up rate with an equatorial velocity of Ë 275 km s[SUP]-1[/SUP]. We find a polar effective temperature of Ë 10150 K and a pole-to-equator effective temperature difference of Ë 2500 K, much larger than the Ë 300 K derived by Gulliver, Hill, and Adelman. Our model suggests that Vega's cool equatorial atmosphere may have significant convective flux and predicts a significantly cooler spectral energy distribution for Vega as seen by its surrounding debris disk. This work was performed in part under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Michelson Fellowship Program. JPL is managed for NASA by the California Institute of Technology. The CHARA Array is operated by the Center for High Angular Resolution Astronomy with support from Georgia State University and the National Science Foundation, the Keck Foundation and the Packard Foundation. [less ▲]

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See detailAn interferometric study of the Fomalhaut inner debris disk II. Keck Nuller mid-infrared observations
Mennesson, B.; Absil, Olivier ULg; Lebreton, J. et al

in Astrophysical Journal (2013), 763

We report on high contrast mid-infrared observations of Fomalhaut obtained with the Keck Interferometer Nuller (KIN) showing a small resolved excess over the level expected from the stellar photosphere ... [more ▼]

We report on high contrast mid-infrared observations of Fomalhaut obtained with the Keck Interferometer Nuller (KIN) showing a small resolved excess over the level expected from the stellar photosphere. The measured null excess has a mean value of 0.35% +/- 0.10% between 8 and 11 microns and increases from 8 to 13 microns. Given the small field of view of the instrument, the source of this marginal excess must be contained within 2AU of Fomalhaut. This result is reminiscent of previous VLTI K-band observations, which implied the presence of a ~ 0.88% excess, and argued that thermal emission from hot dusty grains located within 6 AU from Fomalhaut was the most plausible explanation. Using a parametric 2D radiative transfer code and a Bayesian analysis, we examine different dust disk structures to reproduce both the near and mid-infrared data simultaneously. While not a definitive explanation of the hot excess of Fomalhaut, our model suggests that the most likely inner few AU disk geometry consists of a two-component structure, with two different and spatially distinct grain populations. The 2 to 11 microns data are consistent with an inner hot ring of very small (~ 10 to 300 nm) carbon-rich grains concentrating around 0.1AU. The second dust population consists of larger grains (size of a few microns to a few tens of microns) located further out in a colder region where regular astronomical silicates could survive, with an inner edge around 1AU. From a dynamical point of view, the presence of the inner concentration of sub-micron sized grains is surprising, as such grains should be expelled from the inner planetary system by radiation pressure within only a few years. This could either point to some inordinate replenishment rates (e.g. many grazing comets coming from an outer reservoir) or to the existence of some braking mechanism preventing the grains from moving out. [less ▲]

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See detailAn Interferometric Study of the Fomalhaut Inner Debris Disk. I. Near-Infrared Detection of Hot Dust with VLTI/VINCI
Absil, Olivier ULg; Mennesson, Bertrand; Le Bouquin, Jean-Baptiste et al

in Astrophysical Journal (2009), 704

The innermost parts of dusty debris disks around main-sequence stars are currently poorly known due to the high contrast and small angular separation with their parent stars. Using near-infrared ... [more ▼]

The innermost parts of dusty debris disks around main-sequence stars are currently poorly known due to the high contrast and small angular separation with their parent stars. Using near-infrared interferometry, we aim to detect the signature of hot dust around the nearby A4 V star Fomalhaut, which has already been suggested to harbor a warm dust population in addition to a cold dust ring located at about 140 AU. Archival data obtained with the VINCI instrument at the VLTI are used to study the fringe visibility of the Fomalhaut system at projected baseline lengths ranging from 4 m to 140 m in the K band. A significant visibility deficit is observed at short baselines with respect to the expected visibility of the sole stellar photosphere. This is interpreted as the signature of resolved circumstellar emission, producing a relative flux of 0.88% ± 0.12% with respect to the stellar photosphere. While our interferometric data cannot directly constrain the morphology of the excess emission source, complementary data from the literature allow us to discard an off-axis point-like object as the source of circumstellar emission. We argue that the thermal emission from hot dusty grains located within 6 AU from Fomalhaut is the most plausible explanation for the detected excess. Our study also provides a revised limb-darkened diameter for Fomalhaut (theta_LD = 2.223 ± 0.022 mas), taking into account the effect of the resolved circumstellar emission. Based on observations made with ESO Telescopes at the Paranal Observatory (public VINCI commissioning data). [less ▲]

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See detailAn interferometric study of the Fomalhaut inner debris disk. III. Detailed models of the exozodiacal disk and its origin
Lebreton, J; van Lieshout, R; Augereau, J-C et al

in Astronomy and Astrophysics (2013), 555

Context. Debris disks are thought to be extrasolar analogues to the Solar System planetesimal belts. The star Fomalhaut harbors a cold debris belt at 140AU comparable to the Edgeworth-Kuiper belt, as well ... [more ▼]

Context. Debris disks are thought to be extrasolar analogues to the Solar System planetesimal belts. The star Fomalhaut harbors a cold debris belt at 140AU comparable to the Edgeworth-Kuiper belt, as well as evidence for a warm dust component, unresolved by single-dish telescopes, that is suspected to be a bright analogue to the Solar System's zodiacal dust. Aims. Interferometric observations obtained with the VLTI/VINCI instrument and the Keck Interferometer Nuller have identi fied near- and mid-infrared excesses attributed respectively to hot and warm exozodiacal dust residing in the inner few AU of the Fomalhaut environment. We aim to characterize the properties of this double inner dust belt and to unveil its origin. Methods.We perform parametric modelling of the exozodiacal disk ("exozodi") using the GRaTer radiative transfer code in order to reproduce the interferometric data, complemented by mid- to far-infrared photometric measurements from Spitzer and Herschel. A detailed treatment of sublimation temperatures is introduced to explore the hot population at the size-dependent sublimation rim. We then use an analytical approach to test successively several source mechanisms for the dust and suspected parent bodies. Results. A good fi t to the multi-wavelength data is found by two distinct dust populations: (1) a population of very small (0.01 to 0.5 µ m) and therefore unbound, hot dust grains con ned in a narrow region ( ~0.1 - 0.3 AU) at the sublimation rim of carbonaceous material; (2) a population of bound grains at 2AU that is protected from sublimation and has a larger mass despite its fainter flux level. We propose that the hot dust is produced by the release of small carbon grains following the disruption of dust aggregates that originate from the warm component. A mechanism such as gas braking is required to further con ne the small grains for long enough. In situ dust production could hardly be ensured for the age of the star and we conclude that the observed amount of dust is triggered by intense dynamical activity. Conclusions. Fomalhaut may be representative of exozodis that are currently being surveyed at near and mid-infrared wavelengths worldwide. We propose a framework for reconciling the "hot exozodi phenomenon" with theoretical constraints: the hot component of Fomalhaut is likely the "tip of the iceberg" as it could derive from the more massive, but fainter, warm dust component residing near the ice line. This inner disk exhibits interesting morphology and can be considered a prime target for future exoplanet research. [less ▲]

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See detailInterférométrie de speckle en infrarouge thermique
Vandenrijt, Jean-François ULg; Georges, Marc ULg

in Résumés du Huitième colloque francophone Méthodes et Techniques Optiques pour l'Industrie (2007, November)

L’utilisation de l'interférométrie de speckle (ESPI) sur des objets opaques diffusants à une longueur d’onde de 10 µm en utilisant une caméra thermographique commerciale est présentée pour la première ... [more ▼]

L’utilisation de l'interférométrie de speckle (ESPI) sur des objets opaques diffusants à une longueur d’onde de 10 µm en utilisant une caméra thermographique commerciale est présentée pour la première fois à notre connaissance. L’idée d’utiliser une longueur d’onde plus grande que les longueurs d’onde visibles habituelles est de rendre les mesures de déplacements par des techniques holographiques moins sensibles aux perturbations extérieures. Dans cet article, nous discutons certains aspect particuliers dûs à l’accroissement de la longueur d’onde dans le domaine thermique de 10 µm. Nous montrons ensuite les résultats de mesures de rotations dans le plan d’une plaque métallique. Nous avons utilisé la technique du décalage de phase pour obtenir des mesures quantitatives qui sont corrélées par des mesures menées en parallèle avec un théodolite. [less ▲]

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See detailInterférométrie destructive: du sol à l’espace
Absil, Olivier ULg

Scientific conference (2005, March 22)

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See detailInterférométrie holographique avec cristaux photoréfractifs en régime impulsionnel. Développements et résultats préliminaires
Georges, Marc ULg; Pauliat, Gilles; Lemaire, Philippe et al

in Actes du 10e séminaire SFO/HOLO3 : Nouveaux moyens optiques pour l'industrie (1998, November)

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See detailInterférométrie holographique et de speckle en infrarouge thermique : développements actuels, applications et perspectives
Georges, Marc ULg

in Smigielski, P. (Ed.) Actes du Onzième colloque francophone Méthodes et Techniques Optiques pour l'Industrie (2010, November)

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See detailInterférométrie holographique photoréfractive : nouveaux développements et applications récentes
Thizy, Cédric ULg; Georges, Marc ULg; Hustinx, Guy-Michel et al

Conference (2008, November)

Les cristaux photoréfractifs permettent l'enregistrement holographique dynamique in-situ et une réutilisabilité infinie. Aussi ils possèdent des propriétés spécifiques que d'autres matériaux ... [more ▼]

Les cristaux photoréfractifs permettent l'enregistrement holographique dynamique in-situ et une réutilisabilité infinie. Aussi ils possèdent des propriétés spécifiques que d'autres matériaux holographiques n'ont pas et qui peuvent être utilisées de manière avantageuse en interférométrie holographique. Depuis 15 ans, le CSL développe des techniques d'interférométrie holographique et des instruments basés sur des cristaux de Bi12SiO20 (BSO). Le comportement dynamique de ces derniers permet une grande souplesse d'utilisation de l'interférométrie holographique, à l'instar des techniques basées sur l'enregistrement numérique, tout en fournissant des interférogrammes de meilleure résolution que celles-ci (pas de bruit de speckle, pas de filtrage nécessaire). Par le passé, nous avons déjà présenté une large gamme d'applications en métrologie, contrôle non destructif et mesures vibratoires. Ici nous présentons des applications industrielles récentes obtenue avec une caméra holographique photoréfractive commercialisée. Cette dernière a été utilisée avec succès dans des applications très demandeuses, notamment en terme de résolution. [less ▲]

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See detailInterférométrie holographique sur base de cristaux photoréfractifs dynamiques et lasers à double impulsion : le projet européen PHIFE
Georges, Marc ULg; Thizy, Cédric ULg; Lemaire, Philippe et al

in Smigielski, P. (Ed.) Actes du Cinquième colloque francophone Méthodes et Techniques Optiques pour l'Industrie (2004, November)

Les cristaux photoréfractifs sont des supports holographiques dynamiques (auto-enregistrables, effaçables et indéfiniment réutilisables) qui permettent l'acquisition rapide d'hologrammes utilisables en ... [more ▼]

Les cristaux photoréfractifs sont des supports holographiques dynamiques (auto-enregistrables, effaçables et indéfiniment réutilisables) qui permettent l'acquisition rapide d'hologrammes utilisables en interférométrie holographique. De plus, certaines de leurs propriétés cristallines permettent l'obtention d'interférogrammes de qualité incomparable. Nous avons déjà présenté à maintes reprises les développements et applications d'instruments de métrologie basés sur ces cristaux avec des lasers continus. Des expériences préliminaires sur base de lasers à simple impulsion avaient aussi été montrées. Nous présentons ici la suite de ces expériences et qui ont lieu dans le cadre du projet européen PHIFE "Pulsed Holographic Interferometer for the analysis of Fast Events". PHIFE a pour objectif le développement d'un instrument à champ complet fonctionnant avec un laser YAG Q-switch à double impulsion. [less ▲]

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