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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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See detailInterférométrie RSO et analyses géomorphométriques à caractère tectonique en Jordanie.
Cornet, Yves ULg; De Rauw, Dominique ULg; Ozer, André ULg et al

in Dubois, J. M.; Bernier, M.; Fortin, J. P. (Eds.) et al Série Actualité scientifique - La réalité de terrain en télédétection: pratiques et méthodes (1998)

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See detailInterferon Response Factor 3 is essential for house dust mite-induced airway allergy
Marichal, Thomas ULg; Bedoret, Denis; Mesnil, Claire et al

Conference (2011, May)

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See detailInterferon Response Factor 3 is essential for house dust mite-induced airway allergy
Marichal, Thomas ULg; Bedoret, Denis; Mesnil, Claire ULg et al

in Journal of Allergy and Clinical Immunology (The) (2010), 126(4), 836-844

IRF3, mainly known as a central orchestrator of antiviral responses, is required for proallergic functions of dendritic cells in response to aeroallergens. Thus, this study demonstratively identifies a ... [more ▼]

IRF3, mainly known as a central orchestrator of antiviral responses, is required for proallergic functions of dendritic cells in response to aeroallergens. Thus, this study demonstratively identifies a new pathway potentially implicated in the etiology of airway allergy [less ▲]

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See detailInterferon Response Factor 3 is required for airway allergy to house dust mite in mice
Marichal, Thomas ULg; Bedoret Denis; Mesnil, Claire ULg et al

in Short Book of the Annual Congress of the Euopean Respiratory Society (ERS), Barcelone (2010, September)

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See detailInterferon Response Factor-3 is essential for house dust mite-induced airway allergy
Marichal, Thomas ULg; Bedoret Denis; Mesnil Claire et al

in Proceedings of the Belgian Thoracic Society Annual Meeting (2011, May 23)

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See detailInterferon-induced Sus scrofa Mx1 blocks endocytic traffic of incoming influenza A virus particles
Palm, Mélanie; Garigliany, Mutien-Marie ULg; Cornet, François ULg et al

in Veterinary Research (2010), 41(3), 29

The interferon-induced Mx proteins of vertebrates are dynamin-like GTPases, some isoforms of which can additionally inhibit the life cycle of certain RNA viruses. Here we show that the porcine Mx1 protein ... [more ▼]

The interferon-induced Mx proteins of vertebrates are dynamin-like GTPases, some isoforms of which can additionally inhibit the life cycle of certain RNA viruses. Here we show that the porcine Mx1 protein (poMx1) inhibits replication of influenza A virus and we attempt to identify the step at which the viral life cycle is blocked. In infected cells expressing poMx1, the level of transcripts encoding the viral nucleoprotein is significantly lower than normal, even when secondary transcription is prevented by exposure to cycloheximide. This reveals that a pretranscriptional block participates to the anti-influenza activity. Binding and internalization of incoming virus particles are normal in the presence of poMx1 but centripetal traffic to the late endosomes is interrupted. Surprisingly but decisively, poMx1 significantly alters binding of early endosome autoantigen 1 to early endosomes and/or early endosome size and spatial distribution. This is compatible with impairment of traffic of the endocytic vesicles to the late endosomes. [less ▲]

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See detailThe Interferon-Inducible Mouse Apolipoprotein L9 and Prohibitins Cooperate to Restrict Theiler's Virus Replication.
Kreit, Marguerite; Vertommen, Didier; Gillet, Laurent ULg et al

in PloS one (2015), 10(7), 0133190

Apolipoprotein L9b (Apol9b) is an interferon-stimulated gene (ISG) that has antiviral activity and is weakly expressed in primary mouse neurons as compared to other cell types. Here, we show that both ... [more ▼]

Apolipoprotein L9b (Apol9b) is an interferon-stimulated gene (ISG) that has antiviral activity and is weakly expressed in primary mouse neurons as compared to other cell types. Here, we show that both Apol9 isoforms (Apol9b and Apol9a) inhibit replication of Theiler's murine encephalomyelitis virus (TMEV) but not replication of vesicular stomatitis virus (VSV), Murid herpesvirus-4 (MuHV-4), or infection by a lentiviral vector. Apol9 genes are strongly expressed in mouse liver and, to a lesser extent, in pancreas, adipose tissue and intestine. Their expression is increased by type I interferon and viral infection. In contrast to genuine apolipoproteins that are involved in lipid transport, ApoL9 has an intracytoplasmic localization and does not seem to be secreted. The cytoplasmic localization of ApoL9 is in line with the observation that ApoL9 inhibits the replication step of TMEV infection. In contrast to human ApoL6, ApoL9 did not sensitize cells to apoptosis, in spite of the presence of a conserved putative BH3 domain, required for antiviral activity. ApoL9a and b isoforms interact with cellular prohibitin 1 (Phb1) and prohibitin 2 (Phb2) and this interaction might contribute to ApoL9 antiviral activity. Knocking down Phb2 slightly increased TMEV replication, irrespective of ApoL9 overexpression. The antiviral activity of prohibitins against TMEV contrasts with the pro-viral activity of prohibitins observed for VSV and reported previously for Dengue 2 (DENV-2), Chikungunya (CHIKV) and influenza H5N1 viruses. ApoL9 is thus an example of ISG displaying a narrow antiviral range, which likely acts in complex with prohibitins to restrict TMEV replication. [less ▲]

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See detailLes interférons de type 1 et leur fonction antivirale
Leroy, Michael; Desmecht, Daniel ULg

in Annales de Médecine Vétérinaire (2006), 150(2), 73-107

Type I interferons are part of the innate immune system involved in the first line defense against invasion, replication and spreading of pathogens such as viruses. Through specific membrane or ... [more ▼]

Type I interferons are part of the innate immune system involved in the first line defense against invasion, replication and spreading of pathogens such as viruses. Through specific membrane or intracellular receptors, virus entry induces the expression of type I interferons which stimulates the cells through an autocrine and paracrine manner. Interferons are polypeptides that stimulate cells through membrane receptors. They induce a cascade of events leading to the synthesis of many proteins some of which having specific antiviral properties. The most characterized are the MX proteins, the 2’5’ oligoadenylate synthetase/ ribonuclease L pathway and the double-stranded RNA-dependent protein kinase R system. Recently, the protein ISG20 has been involved in the specific antiviral function of type I interferons. The interferons act on multiple steps of the viral cycle including penetration, decapsidation, mRNA transcription, protein synthesis, genome replication, assembling and excretion of viral particles. Nowadays, due to their major efficiency, type I interferons are used in therapeutics against some viral infections and cancers. [less ▲]

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See detailInterfollicular fibrosis and organohalogens in the thyroid of the harbour porpoise (phocoena phocoena) of the British and Belgian coasts
Schnitzler, Joseph ULg; Das, Krishna ULg; Beineke, Andreas et al

Conference (2005, October 27)

Previous studies have described high levels of polychlorobiphenyls (PCB), p,p`-dichlordiphenyl-dichlorethen (DDT), p,p`-dichlordiphenyl-trichlorethan (DDE) and polybrominated diphenylether (PBDE) in the ... [more ▼]

Previous studies have described high levels of polychlorobiphenyls (PCB), p,p`-dichlordiphenyl-dichlorethen (DDT), p,p`-dichlordiphenyl-trichlorethan (DDE) and polybrominated diphenylether (PBDE) in the blubber of the harbour porpoise (Phocoena phocoena) from the North Sea raising the question of a potential endocrine disruption in this species. In the present study, the thyroids of 36 harbour porpoises from the British and the Belgian coast have been collected for histological and immunohistological investigations. The number and mean diameter of follicles and the relative distribution of follicular, connective and vascular tissues (%) were quantified in the thyroid of each individual. Then, the relationship between the thyroid morphometry data and previously described organic compounds (namely PCB, DDT, DDE and PBDE) was investigated using factor analysis and multiple regressions. The results of this work were compared to the previous study of harbour porpoises from the German (North and Baltic Seas), Norwegian and Icelandic coasts. Thyroid morphology was similar between the harbour porpoises from the British and Belgian coast. Compared to the previous study, the thyroids differed strongly between sampling sites. Porpoises from the German (North and Baltic Seas) and Norwegian coasts displayed a high percentage of connective tissues between 30 and 38% revealing severe inter-follicular fibrosis. The thyroids of Icelandic coasts displayed only a light inter-follicular fibrosis (percentage of connective tissue of 3%). The thyroids of the porpoises from the British and Belgian coasts occupied an intermediary place with a moderate fibrosis (percentage of connective tissue of 10%). A relation between mean diameter of follicles and the body size and mass suggesting a downward trend of activity of the thyroid with increasing body size and mass and thus, the age of the porpoises. A correlation-based principal component analysis (PCA) revealed one principal components explaining 69% of the total variance. The variables PCB, PBDE, DDT, and DDE compounds loaded highest on PC1. Our results pointed out a relationship between PCBs, PBDE, DDE and DDT (PC1) compounds and interfollicular fibrosis in the thyroids of harbour porpoises from the German coast of the Baltic Sea. The present report supports the hypothesis of a contaminant-induced thyroid fibrosis in harbour porpoises raising the question of the long term-viability in highly polluted areas [less ▲]

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