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See detailLe chez soi des animaux
Despret, Vinciane ULg

Book published by actes sud (2017)

Le livre raconte aux enfants des histoires sur le rapport des animaux à leur habitat et à leur identité. Pour comprendre qu’au-delà des ressemblances et des différences, “ainsi va la vie sur cette terre ... [more ▼]

Le livre raconte aux enfants des histoires sur le rapport des animaux à leur habitat et à leur identité. Pour comprendre qu’au-delà des ressemblances et des différences, “ainsi va la vie sur cette terre qui est, pour chacun et pour nous tous, notre chez-nous”. [less ▲]

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See detailThe W. M. Keck Observatory infrared vortex coronagraph and a first image of HIP79124 B
Serabyn, Eugene; Huby, Elsa ULg; Matthews, Keith et al

in Astronomical Journal (The) (2017), 153(1), 43

An optical vortex coronagraph has been implemented within the NIRC2 camera on the Keck II telescope and used to carry out on-sky tests and observations. The development of this new L'-band observational ... [more ▼]

An optical vortex coronagraph has been implemented within the NIRC2 camera on the Keck II telescope and used to carry out on-sky tests and observations. The development of this new L'-band observational mode is described, and an initial demonstration of the new capability is presented: a resolved image of the low-mass companion to HIP79124, which had previously been detected by means of interferometry. With HIP79124 B at a projected separation of 186.5 mas, both the small inner working angle of the vortex coronagraph and the related imaging improvements were crucial in imaging this close companion directly. Due to higher Strehl ratios and more relaxed contrasts in L' band versus H band, this new coronagraphic capability will enable high-contrast small-angle observations of nearby young exoplanets and disks on a par with those of shorter-wavelength extreme adaptive optics coronagraphs. [less ▲]

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See detailCharacterization of the inner disk around HD 141569 A from Keck/NIRC2 L-band vortex coronagraphy
Mawet, Dimitri; Choquet, Élodie; Absil, Olivier ULg et al

in Astronomical Journal (The) (2017), 153(1), 44

HD 141569 A is a pre-main sequence B9.5 Ve star surrounded by a prominent and complex circumstellar disk, likely still in a transition stage from protoplanetary to debris disk phase. Here, we present a ... [more ▼]

HD 141569 A is a pre-main sequence B9.5 Ve star surrounded by a prominent and complex circumstellar disk, likely still in a transition stage from protoplanetary to debris disk phase. Here, we present a new image of the third inner disk component of HD 141569 A made in the L' band (3.8 micron) during the commissioning of the vector vortex coronagraph recently installed in the near-infrared imager and spectrograph NIRC2 behind the W.M. Keck Observatory Keck II adaptive optics system. We used reference point spread function subtraction, which reveals the innermost disk component from the inner working distance of $\simeq 23$ AU and up to $\simeq 70$ AU. The spatial scale of our detection roughly corresponds to the optical and near-infrared scattered light, thermal Q, N and 8.6 micron PAH emission reported earlier. We also see an outward progression in dust location from the L'-band to the H-band (VLT/SPHERE image) to the visible (HST/STIS image), likely indicative of dust blowout. The warm disk component is nested deep inside the two outer belts imaged by HST NICMOS in 1999 (respectively at 406 and 245 AU). We fit our new L'-band image and spectral energy distribution of HD 141569 A with the radiative transfer code MCFOST. Our best-fit models favor pure olivine grains, and are consistent with the composition of the outer belts. While our image shows a putative very-faint point-like clump or source embedded in the inner disk, we did not detect any true companion within the gap between the inner disk and the first outer ring, at a sensitivity of a few Jupiter masses. [less ▲]

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See detailOmbres de réalité
Choffray, Jean-Marie ULg

Book published by Amazon, Kindle Edition - Seconde édition (2017)

« Ombres de réalité » a pour objectif de partager avec vous nombre d’erreurs personnelles – factuelles et d’appréciation –, à la lumière de ce que d’autres ont eu l’élégance de nous transmettre. Le socle ... [more ▼]

« Ombres de réalité » a pour objectif de partager avec vous nombre d’erreurs personnelles – factuelles et d’appréciation –, à la lumière de ce que d’autres ont eu l’élégance de nous transmettre. Le socle de la réalité, lieu de convergence de ses ombres, et que décrit à merveille la comédie humaine, ne peut jamais être approché qu’au travers d’une recherche sincère et permanente. Apprendre à désapprendre résolument, apprendre à reconstruire patiemment, et apprendre à transmettre modestement, constituent le but ultime de la vie. Personnellement, je n’en vois pas d’autre aujourd’hui. Après une brève introduction, ou « Sortie de l’ombre », de courts chapitres couvrent un thème particulier, généralement à la lumière d’observations, d’expériences personnelles, ou de lectures qui m’ont touché. La sélection et l’ordre des sujets ne traduit aucun souci particulier, même si je ne crois plus beaucoup au hasard. Tous deux pourraient évoluer au fil des révisions que connaîtra ce texte dans les années à venir. Le choix actuel va de « Chacun pour soi » au « Secret du silence », en passant par « L’aventure à deux », « La foire aux illusions », « La tyrannie des marchés », « L’intérêt général », « Non ! merci », et « Une chance d’être ». Chaque thème peut être exploré isolément. A vous, donc, de constituer votre menu en fonction de votre curiosité et de votre appétit. [less ▲]

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See detailHow should proxies of Cognitive Reserve be evaluated in a population of healthy older adults?
Grotz, Catherine ULg; Seron, Xavier; Van Wissen, Marie et al

in International Psychogeriatrics (2017), 29(1), 123-136

Background: While some tools have been developed to estimate an individual’s cognitive reserve (CR), no study has assessed the adequacy of the method used for assessing these CR proxy indicators ... [more ▼]

Background: While some tools have been developed to estimate an individual’s cognitive reserve (CR), no study has assessed the adequacy of the method used for assessing these CR proxy indicators. Therefore, we aimed to determine the most appropriate method to estimate CR by comparing two approaches: 1) the common assessment of CR proxies in the literature (e.g., years of education) and 2) the calculation of a comprehensive index based on most significant parameters used in the estimation of CR. Methods: Data on CR proxies: (i.e., education, occupation and leisure activities) were obtained in a sample of 204 older adults. Regression analyses were used to develop the two indices of CR (i.e., ICR-standard and ICR-detailed) and to determine which index best represented the level of one’s CR. Results: The ICR-standard was calculated using a combination of the three most common measures of reserve in the literature: number of schooling years, complexity of the primary occupation and amount of current participation in stimulating activities. The ICR-detailed was calculated using the most significant parameters (established in initial analyses) of CR: highest level of education combined with the number of training courses, last occupation and amount of current participation in social and intellectual activities. The comparison of both indices showed that higher levels of ICR-standard and ICR-detailed were associated with a greater minimization of the effects of age on cognition. However, the ICR-detailed was more strongly associated to this minimization than the ICR-standard, suggesting that the ICR-detailed best reflect one’s CR. Conclusion: This study is the first to show that it is of great importance to question methods measuring CR proxies in order to develop a clinical tool allowing a comprehensive and accurate estimation of CR. [less ▲]

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See detailPaleogenetic study of ancient DNA suggestive of X-Linked acrogigantism
Beckers, Albert ULg; Fernandes, Daniel; Fina, Frederic et al

in Endocrine-Related Cancer (2017)

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See detailAux armes, professeurs de sciences !
du Jardin, Patrick ULg

Article for general public (2017)

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See detailHot-Melt Extrusion as a Continuous Manufacturing Process to Form Ternary Cyclodextrin Inclusion Complexes
Thiry, Justine ULg; Krier, Fabrice; Ratwatte, Shenelka et al

in European Journal of Pharmaceutical Sciences (2017), 96

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See detailDiscovery of a low-mass companion inside the debris ring surrounding the F5V star HD 206893
Milli, J.; Hibon, P.; Christiaens, Valentin ULg et al

in Astronomy and Astrophysics (2017), 597

<BR /> Aims: Uncovering the ingredients and the architecture of planetary systems is a very active field of research that has fuelled many new theories on giant planet formation, migration, composition ... [more ▼]

<BR /> Aims: Uncovering the ingredients and the architecture of planetary systems is a very active field of research that has fuelled many new theories on giant planet formation, migration, composition, and interaction with the circumstellar environment. We aim at discovering and studying new such systems, to further expand our knowledge of how low-mass companions form and evolve. <BR /> Methods: We obtained high-contrast H-band images of the circumstellar environment of the F5V star HD 206893, known to host a debris disc never detected in scattered light. These observations are part of the SPHERE High Angular Resolution Debris Disc Survey (SHARDDS) using the InfraRed Dual-band Imager and Spectrograph (IRDIS) installed on VLT/SPHERE. <BR /> Results: We report the detection of a source with a contrast of 3.6 × 10[SUP]-5[/SUP] in the H-band, orbiting at a projected separation of 270 milliarcsec or 10 au, corresponding to a mass in the range 24 to 73 M[SUB]Jup[/SUB] for an age of the system in the range 0.2 to 2 Gyr. The detection was confirmed ten months later with VLT/NaCo, ruling out a background object with no proper motion. A faint extended emission compatible with the disc scattered light signal is also observed. <BR /> Conclusions: The detection of a low-mass companion inside a massive debris disc makes this system an analog of other young planetary systems such as β Pictoris, HR 8799 or HD 95086 and requires now further characterisation of both components to understand their interactions. [less ▲]

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See detailThe EACVI Echo Handbook.
Nchimi Longang, Alain ULg

in European Heart Journal (2017)

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See detailFirst limits on the occurrence rate of short-period planets orbiting brown dwarfs
He, Matthias Y.; Triaud, Amaury H. M. J.; Gillon, Michaël ULg

in Monthly Notices of the Royal Astronomical Society (2017), 464

Planet formation theories predict a large but still undetected population of short-period terrestrial planets orbiting brown dwarfs. Should specimens of this population be discovered transiting relatively ... [more ▼]

Planet formation theories predict a large but still undetected population of short-period terrestrial planets orbiting brown dwarfs. Should specimens of this population be discovered transiting relatively bright and nearby brown dwarfs, the Jupiter-size and the low luminosity of their hosts would make them exquisite targets for detailed atmospheric characterisation with JWST and future ground-based facilities. The eventual discovery and detailed study of a significant sample of transiting terrestrial planets orbiting nearby brown dwarfs could prove to be useful not only for comparative exoplanetology but also for astrobiology, by bringing us key information on the physical requirements and timescale for the emergence of life. In this context, we present a search for transit-signals in archival time-series photometry acquired by the Spitzer Space Telescope for a sample of 44 nearby brown dwarfs. While these 44 targets were not particularly selected for their brightness, the high precision of their Spitzer light curves allows us to reach sensitivities below Earth-sized planets for 75% of the sample and down to Europa-sized planets on the brighter targets. We could not identify any unambiguous planetary signal. Instead, we could compute the first limits on the presence of planets on close-in orbits. We find that within a 1.28 day orbit, the occurrence rate of planets with a radius between 0.75 and 3.25 R$_\oplus$ is {\eta} < 67 $\pm$ 1%. For planets with radii between 0.75 and 1.25 R$_\oplus$, we place a 95% confident upper limit of {\eta} < 87 $\pm$ 3%. If we assume an occurrence rate of {\eta} = 27% for these planets with radii between 0.75 and 1.25 R$_\oplus$, as the discoveries of the Kepler-42b and TRAPPIST-1b systems would suggest, we estimate that 175 brown dwarfs need to be monitored in order to guarantee (95%) at least one detection. [less ▲]

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See detailWater loss from terrestrial planets orbiting ultracool dwarfs: implications for the planets of TRAPPIST-1
Bolmont, E.; Selsis, F.; Owen, J. E. et al

in Monthly Notices of the Royal Astronomical Society (2017), 464

Ultracool dwarfs (UCD; $T_{\rm eff}<\sim3000~$K) cool to settle on the main sequence after $\sim$1 Gyr. For brown dwarfs, this cooling never stops. Their habitable zone (HZ) thus sweeps inward at least ... [more ▼]

Ultracool dwarfs (UCD; $T_{\rm eff}<\sim3000~$K) cool to settle on the main sequence after $\sim$1 Gyr. For brown dwarfs, this cooling never stops. Their habitable zone (HZ) thus sweeps inward at least during the first Gyr of their lives. Assuming they possess water, planets found in the HZ of UCDs have experienced a runaway greenhouse phase too hot for liquid water prior to entering the HZ. It has been proposed that such planets are desiccated by this hot early phase and enter the HZ as dry worlds. Here we model the water loss during this pre-HZ hot phase taking into account recent upper limits on the XUV emission of UCDs and using 1D radiation-hydrodynamic simulations. We address the whole range of UCDs but also focus on the planets recently found around the $0.08~M_\odot$ dwarf TRAPPIST-1. Despite assumptions maximizing the FUV-photolysis of water and the XUV-driven escape of hydrogen, we find that planets can retain significant amounts of water in the HZ of UCDs, with a sweet spot in the $0.04$-$0.06~M_\odot$ range. We also studied the TRAPPIST-1 system using observed constraints on the XUV-flux. We find that TRAPPIST-1b and c may have lost as much as 15 Earth Oceans and planet d -- which might be inside the HZ -- may have lost less than 1 Earth Ocean. Depending on their initial water contents, they could have enough water to remain habitable. TRAPPIST-1 planets are key targets for atmospheric characterization and could provide strong constraints on the water erosion around UCDs. [less ▲]

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See detailRossiter-McLaughlin models and their effect on estimates of stellar rotation, illustrated using six WASP systems
Brown, D. J. A.; Triaud, A. H. M. J.; Doyle, A. P. et al

in Monthly Notices of the Royal Astronomical Society (2017), 464

We present new measurements of the projected spin--orbit angle $\lambda$ for six WASP hot Jupiters, four of which are new to the literature (WASP-61, -62, -76, and -78), and two of which are new analyses ... [more ▼]

We present new measurements of the projected spin--orbit angle $\lambda$ for six WASP hot Jupiters, four of which are new to the literature (WASP-61, -62, -76, and -78), and two of which are new analyses of previously measured systems using new data (WASP-71, and -79). We use three different models based on two different techniques: radial velocity measurements of the Rossiter--McLaughlin effect, and Doppler tomography. Our comparison of the different models reveals that they produce projected stellar rotation velocities ($v \sin I_{\rm s}$) measurements often in disagreement with each other and with estimates obtained from spectral line broadening. The Bou\'e model for the Rossiter--McLaughlin effect consistently underestimates the value of $v\sin I_{\rm s}$ compared to the Hirano model. Although $v \sin I_s$ differed, the effect on $\lambda$ was small for our sample, with all three methods producing values in agreement with each other. Using Doppler tomography, we find that WASP-61\,b ($\lambda=4^\circ.0^{+17.1}_{-18.4}$), WASP-71\,b ($\lambda=-1^\circ.9^{+7.1}_{-7.5}$), and WASP-78\,b ($\lambda=-6^\circ.4\pm5.9$) are aligned. WASP-62\,b ($\lambda=19^\circ.4^{+5.1}_{-4.9}$) is found to be slightly misaligned, while WASP-79\,b ($\lambda=-95^\circ.2^{+0.9}_{-1.0}$) is confirmed to be strongly misaligned and has a retrograde orbit. We explore a range of possibilities for the orbit of WASP-76\,b, finding that the orbit is likely to be strongly misaligned in the positive $\lambda$ direction. [less ▲]

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See detailIdentification of complex nonlinearities using cubic splines with automatic discretization
Dossogne, Tilàn ULg; Noël, Jean-Philippe ULg; Kerschen, Gaëtan ULg

in Proceedings of the International Modal Analysis Conference (IMAC) XXXV (2017, January)

One of the major challenges in nonlinear system identification is the selection of appropriate mathematical functions to model the observed nonlinearities. In this context, piecewise polynomials, or ... [more ▼]

One of the major challenges in nonlinear system identification is the selection of appropriate mathematical functions to model the observed nonlinearities. In this context, piecewise polynomials, or splines, offer a simple and flexible representation basis requiring limited prior knowledge. The generally-adopted discretization for splines consists in an even distribution of their control points, termed knots. While this may prove successful for simple nonlinearities, a more advanced strategy is needed for nonlinear restoring forces with strong local variations. The present paper specifically introduces a two-step methodology to select automatically the location of the knots. It proposes to derive an initial model, using nonlinear subspace identification, and incorporating cubic spline basis functions with fixed and equally-spaced abscissas. In a second step, the location of the knots is optimized iteratively by minimizing a least-squares cost function. A single-degree-of-freedom system with a discontinuous stiffness characteristic is considered as a case study. [less ▲]

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See detailAttack-Prevention and Damage-Control Investments in Cybersecurity
Lam, Wing Man Wynne ULg

Scientific conference (2017, January)

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See detailExperimental Assessment of the Influence of Interface Geometries on Structural Dynamic Response
Dossogne, Tilàn ULg; Jerome, Trevor; Lancereau, Damien et al

in Proceedings of the International Modal Analysis Conference (IMAC) XXXV (2017, January)

Jointed interfaces are sources of the greatest amount of uncertainty in the dynamics of a structural assembly. In practice, jointed connections introduce nonlinearity into a system, which is often ... [more ▼]

Jointed interfaces are sources of the greatest amount of uncertainty in the dynamics of a structural assembly. In practice, jointed connections introduce nonlinearity into a system, which is often manifested as a softening response in frequency response, exhibiting amplitude dependent damping and stiffness. Additionally, standard joints are highly susceptible to unrepeatability and variability that make meaningful prediction of the performance of a system prohibitively difficult. This high degree of uncertainty in joint structure predictions is partly due to the physical design of the interface. This paper experimentally assesses the influence of the interface geometry on both the nonlinear and uncertain aspects of jointed connections. The considered structure is the Brake-Reuß beam, which possesses a lap joint with three bolted connections, and can exhibit several different interface configurations. Five configurations with different contact areas are tested, identified, and compared, namely joints with complete contact in the interface, contact only under the pressure cones, contact under an area twice that of the pressure cones, contact only away from the pressure cones and Hertzian contact. The contact only under the pressure cone and Hertzian contact are found to behave linearly in the range of excitation used in this work. The contact area twice that of the pressure cone behaves between the complete contact and contact only under the pressure cone cases. [less ▲]

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See detailTHE LACTOPEROXIDASE SYSTEM, A NATURAL BIOCHEMICAL BIOCONTROL AGENT FOR PRE- AND POST-HARVEST APPLICATIONS
Bafort, Françoise ULg; Parisi, Olivier ULg; Perraudin, Jean-Paul et al

in Journal of Phytopathology (2017), 165(1), 22-34

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