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See detailExopolysaccharides production by selected bacteria
Valepyn, Emmanuel ULg; Paquot, Michel ULg; Nys, Joël

Poster (2011, August)

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See detailExosites Mediate The Anti-Inflammatory Effects Of A Multifunctional Serpin From The Saliva Of The Tick Ixodes Ricinus
Prevot, Pp.; Beschin, A.; Lins, Laurence ULg et al

in Febs Journal (2009), 276(12),

Serine protease inhibitors (serpins) are a structurally related but functionally diverse family of ubiquitous proteins. We previously described Ixodes ricinus immunosuppressor (Iris) as a serpin from the ... [more ▼]

Serine protease inhibitors (serpins) are a structurally related but functionally diverse family of ubiquitous proteins. We previously described Ixodes ricinus immunosuppressor (Iris) as a serpin from the saliva of the tick I. ricinus displaying high affinity for human leukocyte elastase. Iris also displays pleotropic effects because it interferes with both the immune response and hemostasis of the host. It thus inhibits lymphocyte proliferation and the secretion of interferon-gamma or tumor necrosis factor-alpha by peripheral blood mononuclear cells, and also platelet adhesion, coagulation and fibrinolysis. Its ability to interfere with coagulation and fibrinolysis, but not platelet adhesion, depends on the integrity of its antiproteolytic reactive center loop domain. Here, we dissect the mechanisms underlying the interaction of recombinant Iris with peripheral blood mononuclear cells. We show that Iris binds to monocytes/macrophages and inhibits their ability to secrete tumor necrosis factor-alpha. Recombinant Iris also has a protective role in endotoxemic shock. The anti-inflammatory ability of Iris does not depend on its antiprotease activity. Moreover, we pinpoint the exosites involved in this activity. [less ▲]

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See detailExotic animal dermatology
Mignon, Bernard ULg; Losson, Bertrand ULg

Conference (2004)

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See detailEXOTIME: searching for planets around pulsating subdwarf B stars
Schuh, Sonja; Silvotti, Roberto; Lutz, Ronny et al

in Astrophysics & Space Science (2010, October), 329

In 2007, a companion with planetary mass was found around the pulsating subdwarf B star V391 Pegasi with the timing method, indicating that a previously undis- covered population of substellar companions ... [more ▼]

In 2007, a companion with planetary mass was found around the pulsating subdwarf B star V391 Pegasi with the timing method, indicating that a previously undis- covered population of substellar companions to apparently single subdwarf B stars might exist. Following this serendip- itous discovery, the EXOTIME (http://www.na.astro.it/ ~silvotti/exotime/) monitoring program has been set up to follow the pulsations of a number of selected rapidly pul- sating subdwarf B stars on time scales of several years with two immediate observational goals: (1) determine P ̇ of the pulsational periods P (2) search for signatures of substellar companions in O– C residuals due to periodic light travel time variations, which would be tracking the central star’s companion- induced wobble around the centre of mass These sets of data should therefore, at the same time, on the one hand be useful to provide extra constraints for classical asteroseismological exercises from the P ̇ (comparison with “local” evolutionary models), and on the other hand allow one to investigate the preceding evolution of a target in terms of possible “binary” evolution by extending the otherwise unsuccessful search for companions to potentially very low masses. While timing pulsations may be an observationally ex- pensive method to search for companions, it samples a dif- ferent range of orbital parameters, inaccessible through or- bital photometric effects or the radial velocity method: the latter favours massive close-in companions, whereas the timing method becomes increasingly more sensitive toward wider separations. In this paper we report on the status of the on-going ob- servations and coherence analysis for two of the currently five targets, revealing very well-behaved pulsational charac- teristics in HS 0444+0458, while showing HS 0702+6043 to be more complex than previously thought. [less ▲]

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See detailL'exotisme intérieur. Lévi-Strauss et la question de l'art
Steinmetz, Rudy ULg

in Art&Fact (1990)

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See detailExotisme zonder romantiek. Roel Janssen en Dorine Platenga: 'Brazilië'
Vanden Berghe, Kristine ULg

Article for general public (1992)

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See detailExozodiacal discs with ALADDIN: how deep can we go?
Absil, Olivier ULg

Scientific conference (2009, May 12)

Studying the warm inner part of debris discs—-the extrasolar counterparts of the zodiacal dust cloud-—is of prime importance to characterise the global architecture of planetary systems. Furthermore, the ... [more ▼]

Studying the warm inner part of debris discs—-the extrasolar counterparts of the zodiacal dust cloud-—is of prime importance to characterise the global architecture of planetary systems. Furthermore, the possible presence of large quantities of warm dust around nearby main sequence stars is unanimously recognised as a major threat for future space missions dedicated to the direct detection and characterisation of Earth-like planets (either with visible/near-IR coronagraphy or mid-infrared interferometry). As of today, exozodiacal discs have been directly resolved around very few main sequence stars, at a sensitivity level of about 1000 times our zodiacal dust cloud. In this context, the ALADDIN project aims at detecting warm dust populations around nearby main sequence stars with significantly improved sensitivity. In this paper, we present a thorough study of ALADDIN's estimated performance. End-to-end simulations taking into account the specific characteristics of the Antarctic environment have been carried out, showing that a nulling interferometer coupled to a pair of 1-m class telescopes in Antarctica would perform significantly better than a similar instrument working on 8-m class telescopes in a temperate site. Exozodiacal dust density levels as low as 50 times the Solar zodiacal cloud are within reach around most Solar-type stars within 25 pc. Such performance would bring the study of exozodiacal light to a new level, and enable a fine study of terrestrial planet environments. Suitable candidate targets for direct Earth-like planet detection could then be identified among nearby main sequence stars in the Southern hemisphere, and the design of future space missions tuned to cope with the statistical occurrence of bright exozodiacal discs. [less ▲]

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See detailExozodiacal discs with ALADDIN: how faint can we detect them?
Absil, Olivier ULg; Coudé Du Foresto; Barillot, M. et al

in Spinoglio, L.; Epchtein, N. (Eds.) 3rd ARENA Conference: An Astronomical Observatory at CONCORDIA (Dome C, Antarctica) (2010)

In this paper, we describe the expected performance of ALADDIN, a nulling interferometer project optimised for operation at Dome C. After reviewing the main atmospheric parameters pertaining to infrared ... [more ▼]

In this paper, we describe the expected performance of ALADDIN, a nulling interferometer project optimised for operation at Dome C. After reviewing the main atmospheric parameters pertaining to infrared interferometry on the high Antarctic plateau, we shortly describe the ALADDIN instrument and compute its estimated performance in terms of the smallest exozodiacal dust disc density that can be detected. Our estimations are based on a thorough end-to-end software simulator previously developed for the GENIE nulling interferometer project at VLTI. We then propose a possible mission scenario, where the southern target stars of future exo-Earth characterisation missions can be surveyed for the presence of bright exozodiacal discs (>50 zodi) within one winter-over at Concordia. [less ▲]

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See detailExozodiacal discs with infrared interferometry
Absil, Olivier ULg

Scientific conference (2007, March 05)

The detection of the warm inner part of debris discs---the extrasolar counterparts of the zodiacal cloud---is of prime importance to characterise the global architecture of planetary systems. Because of ... [more ▼]

The detection of the warm inner part of debris discs---the extrasolar counterparts of the zodiacal cloud---is of prime importance to characterise the global architecture of planetary systems. Because of the high contrast and small angular separation between the star and the exozodiacal light, high-precision infrared interferometry is the best-suited tool to carry out such observations. In this paper, we review the first detection of an exozodiacal disc by this method recently reported around Vega by Absil et al. (2006), and discuss the currently on-going observing efforts in this domain. We show how interferometric data can give access to the composition and the dynamics (including LHB-like events) of extrasolar planetary systems, and thereby put useful constraints on the presence of small bodies and/or giant planets. This statement is illustrated with new data obtained on various bright Vega-type stars, including Vega itself. Finally, we show how the new generation of interferometric instruments will change our view of debris discs: with their increased sensitivity and imaging capabilities, they will constrain the morphology of bright exozodiacal discs and push the detection limit towards meaningful density levels in the context of future life-finding missions such as Darwin/TPF. [less ▲]

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See detailExozodiacal Disks
Hinz, Phillip; Millan-Gabet, Rafael; Absil, Olivier ULg et al

in Lawson, P. R.; Traub, W. A.; Unwin, S. C. (Eds.) Exoplanet Community Report (2009)

From the viewpoint of direct imaging of exoplanets in the visible or infrared, exozodi dust disks can be both good and bad. An exozodi disk is good if it has structures (cleared regions or resonant clumps ... [more ▼]

From the viewpoint of direct imaging of exoplanets in the visible or infrared, exozodi dust disks can be both good and bad. An exozodi disk is good if it has structures (cleared regions or resonant clumps) that suggest the gravitational presence of planets, however it is bad if the dust fills the instrumental field of view with brightness that swamps the signal from a planet. Unfortunately, it takes very little dust to compete with or overwhelm the light from a planet: an Earth‐twin signal is roughly equal to a 0.1‐AU patch of Solar‐System‐twin zodi, in the visible or infrared. Thus, exozodi measurements are extremely important, but they are also difficult to make. Current limits of detection, in units of the Solar‐System brightness, are a few hundred using the Spitzer Space Telescope, about one hundred with the Keck Interferometer (KI), and about 10 expected from the Large Binocular Telescope Interferometer (LBTI). A small coronagraph or small interferometer in space is needed in order to reach the sensitivity required to detect the glow at the level of our own Solar System. [less ▲]

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See detailThe Exozodiacal Dust Problem for Direct Observations of Exo-Earths
Roberge, Aki; Chen, Christine H; Millan-Gabet, Rafael et al

in Publications of the Astronomical Society of the Pacific [=PASP] (2012), 124

Debris dust in the habitable zones of stars - otherwise known as exozodiacal dust - comes from extrasolar asteroids and comets and is thus an expected part of a planetary system. Background flux from the ... [more ▼]

Debris dust in the habitable zones of stars - otherwise known as exozodiacal dust - comes from extrasolar asteroids and comets and is thus an expected part of a planetary system. Background flux from the Solar System's zodiacal dust and the exozodiacal dust in the target system is likely to be the largest source of astrophysical noise in direct observations of terrestrial planets in the habitable zones of nearby stars. Furthermore, dust structures like clumps, thought to be produced by dynamical interactions with exoplanets, are a possible source of confusion. In this paper, we qualitatively assess the primary impact of exozodical dust on high-contrast direct imaging at optical wavelengths, such as would be performed with a coronagraph. Then we present the sensitivity of previous, current, and near-term facilities to thermal emission from debris dust at all distances from nearby solar-type stars, as well as our current knowledge of dust levels from recent surveys. Finally, we address the other method of detecting debris dust, through high-contrast imaging in scattered light. This method is currently far less sensitive than thermal emission observations, but provides high spatial resolution for studying dust structures. This paper represents the first report of NASA's Exoplanet Exploration Program Analysis Group (ExoPAG). [less ▲]

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See detailExpanding on olfactory communication in a butterfly: cuticular chemicals indicate sex and age in Bicyclus anynana
Heuskin, Stéphanie ULg; Kaltenpoth, M.; Engl, T. et al

in International Society of Chemical Ecology, 28th Annual Meeting. Abstracts (2012, July)

Chemical (olfactory or gustatory) communication is fundamental to most living organisms but widely understudied compared to other channels of communication such as vision and audition, principally in ... [more ▼]

Chemical (olfactory or gustatory) communication is fundamental to most living organisms but widely understudied compared to other channels of communication such as vision and audition, principally in sexual selection . Here we present the first extensive analysis of cuticular chemical diversity in a butterfly, and investigate whether molecules inform potential mating partners about sex and age. Bicyclus anynana was chosen for its well-known potentialities as a lab model in eco-evo-devo studies , . Chemical interactions have been investigated so far in this species with focus on volatile olfactory components: male sexual pheromones composition and their roles in sexual selection , , their change in ratio with male age, inbreeding coefficient, and other factors . Here we aim completing the picture fully and focus on gustatory non-volatile cuticular chemical diversity in this model species. Indeed, as for Drosophila, the courtship of this butterfly is composed of a series of steps that include short-range interactions during which various chemicals may be involved in mate-choice, through olfactory but also gustatory channels of communication (Nieberding et al., data not published). More than hundred cuticular chemicals were identified and quantified by GC-MS analyses on different parts (abdomen, antennae, head, legs and wings) of B. anynana individuals (n=42, 210 GC-MS analyses) of each sex and at different ages (from 1 to 21 days old). The analysis of the chemical distribution was realised by multivariate statistical analyses (perMANOVA). The results led to the conclusion that some cuticular chemicals are indicative for the body parts and can inform about sex and age. [less ▲]

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See detailExpanding the CHARA/FLUOR hot disk survey
Mennesson, B.; Scott, N.; Ten Brummelaar, T. et al

in Journal of Astronomical Instrumentation (2013), 2(2), 1340010

Little is presently known about the hot (>300 K) dust component of debris disks surrounding main sequence stars, similar to the zodiacal dust cloud found in the inner solar system.While extensive surveys ... [more ▼]

Little is presently known about the hot (>300 K) dust component of debris disks surrounding main sequence stars, similar to the zodiacal dust cloud found in the inner solar system.While extensive surveys have been carried out from space, the majority of detections have surprisingly come from the ground, where near infrared interferometric observations have recently revealed small (∼1%) resolved excesses around a dozen nearby main sequence stars. Most of these results have come from the CHARA array “FLUOR” instrument (Mt. Wilson, CA), which has demonstrated the best sensitivity worldwide so far for this type of studies, and has carried out an initial survey of ∼40 stars. In order to further understand the origin of this “hot dust phenomenon”, we will extend this initial survey to a larger number of stars and lower excess detection limits, i.e. higher visibility accuracy providing higher contrast measurements. To this end, two major instrumental developments are underway at CHARA. The first one aims at improving FLUOR’s sensitivity to a median K-band magnitude limit of 5 (making 200 targets available). The second development is based on a method that we recently developed for accurate (better than 0.1%) null depth measurements of stars, and that can be extended to regular interferometric visibility measurements. [less ▲]

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See detailExpanding the scope of controlled radical polymerization via cobalt–tellurium radical exchange reaction
Kermagoret, Anthony ULg; Nakamura, Yasuyuki; Bourguignon, Maxime et al

in ACS Macro Letters (2014), 3(1), 114-118

Cobalt-mediated radical polymerization (CMRP) and tellurium-mediated radical polymerization (TERP) were combined for the first time, offering new perspectives in the precision design of macromolecular ... [more ▼]

Cobalt-mediated radical polymerization (CMRP) and tellurium-mediated radical polymerization (TERP) were combined for the first time, offering new perspectives in the precision design of macromolecular structures. In particular, the present work highlights the benefits of this strategy for the synthesis of novel poly(vinyl acetate)-based block copolymers. A range of well-defined poly(vinyl acetate)s (PVAc) were first produced via CMRP using the bis(acetylacetonato)cobalt(II) complex (Co(acac)2) as a regulating agent. Substitution of a methyltellanyl moiety for Co(acac)2 at the ω-chain end of the precursor was then achieved upon treatment with dimethylditelluride. In contrast to the PVAc prepared by TERP, the ones produced by sequential CMRP and Co/Te exchange reaction almost exclusively consist of regular head-to-tail-TeMe chain-end species that can be activated by TERP. Ultimately, a series of monomers problematic in Co(acac)2-mediated radical polymerization including N-isopropylacrylamide (NIPAM), 2-(dimethylamino)ethyl acrylate (ADAME), n-butyl acrylate (BA), isoprene (IP), and vinylimidazole (NVIm) were polymerized by TERP from the PVAc–TeMe macroinitiators leading to novel diblock copolymers that cannot be made by each technique used separately. [less ▲]

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See detailExpanding the value of your practice with dental implants.
Van Heusden, Alain ULg

Conference (2006)

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See detailAn expanding Universe without dark matter and dark energy
Magain, Pierre ULg

E-print/Working paper (2012)

Assuming that observers located inside the Universe measure a time flow which is different from the time appearing in the Friedmann-Lemaıtre equation, and determining this time flow such that the Universe ... [more ▼]

Assuming that observers located inside the Universe measure a time flow which is different from the time appearing in the Friedmann-Lemaıtre equation, and determining this time flow such that the Universe always appears flat to these observers, we derive a simple cosmological model which allows to explain the velocity dispersions of galaxies in galaxy clusters without introducing dark matter. It also solves the horizon problem without recourse to inflation. Moreover, it explains the present acceleration of the expansion without any resort to dark energy and provides a good fit to the observations of distant supernovæ. Depending on the present value of the matter-energy density, we calculate an age of the Universe between 15.4 and 16.5 billion years, ignificantly larger than the 13.7 billion years of the standard CDM model. Our model has a slower expansion rate in the early epochs, thus leaving more time for the formation of structures such as stars and galaxies. [less ▲]

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See detailExpansion et régression: deux mots clés de la dynamique des populations du martin pêcheur (Alcedo atthis)
Libois, Roland ULg; Hallet, Catherine

in Aves (1989), 26(n° spécial "Actes...."), 93-101

Annual censuses of nest kingfishers are performed since 1973 in the valley of the river Lesse, a tributary of the river Meuse (Belgium). The authors document sharp population fluctuations. It appears that ... [more ▼]

Annual censuses of nest kingfishers are performed since 1973 in the valley of the river Lesse, a tributary of the river Meuse (Belgium). The authors document sharp population fluctuations. It appears that these are mainly due to the weather conditions prevailing at key-periods. Hard winters reduce the numbers, sometimes to a low level, whereas heavy late-spring or early- summer rains involve a bad reproduiction rate (namely through clutch losses following flooding). Hence, the recovery of the nesting population is weakened. In comparison, other factors such as predation, seem to have only a limitid effect. In other respects, the noxious consequences of permanent disturbances are illistrated in the that part of river Lesse where kayak is practised on a large commercial scale. [less ▲]

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