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See detailHubble Space Telescope search for the transit of the Earth-mass exoplanet α Centauri B b
Demory, Brice-Olivier; Ehrenreich, David; Queloz, Didier et al

in Monthly Notices of the Royal Astronomical Society (2015), 450

Results from exoplanet surveys indicate that small planets (super-Earth size and below) are abundant in our Galaxy. However, little is known about their interiors and atmospheres. There is therefore a ... [more ▼]

Results from exoplanet surveys indicate that small planets (super-Earth size and below) are abundant in our Galaxy. However, little is known about their interiors and atmospheres. There is therefore a need to find small planets transiting bright stars, which would enable a detailed characterization of this population of objects. We present the results of a search for the transit of the Earth-mass exoplanet α Centauri B b with the Hubble Space Telescope (HST). We observed α Centauri B twice in 2013 and 2014 for a total of 40 h. We achieve a precision of 115 ppm per 6-s exposure time in a highly saturated regime, which is found to be consistent across HST orbits. We rule out the transiting nature of α Centauri B b with the orbital parameters published in the literature at 96.6 per cent confidence. We find in our data a single transit-like event that could be associated with another Earth-sized planet in the system, on a longer period orbit. Our programme demonstrates the ability of HST to obtain consistent, high-precision photometry of saturated stars over 26 h of continuous observations. [less ▲]

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See detailMulti-period vehicle assignment problem with stochastic transportation order availability
Pironet, Thierry ULg; Crama, Yves ULg

Conference (2015, June 01)

This work investigates optimization techniques for a vehicle-load assignment problem. A company owning a limited fleet of vehicles wants to maximize its operational profit over an infinite horizon divided ... [more ▼]

This work investigates optimization techniques for a vehicle-load assignment problem. A company owning a limited fleet of vehicles wants to maximize its operational profit over an infinite horizon divided into periods. The profit stems from revenues for transporting full truckloads and costs derived from waiting idle and moving unladen. The stochastic component of the problem arises from projections on the realization of each transportation order, i.e. load. The methodology is based on optimizing decisions for deterministic scenarios. Several policies are generated in this way, from simple heuristics to more complex approaches, such as consensus and restricted expectation algorithms, up to policies derived from network flow models formulated over subtrees of scenarios. Myopic and a-posteriori deterministic optimizations models are used to compute bounds allowing for performance evaluation. Tests are performed on various instances featuring different number of loads, graph sizes, sparsity, and probability distributions. Performances are compared statistically over paired samples. The robustness of various policies with respect to erroneous évaluations of the probability distributions is also analyzed. [less ▲]

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See detailBIOREFINE Project – Recovery of useful nutrients from organic wastes produced in five European countries (3AV.3.55)
Tarayre, Cédric ULg; De Clercq, Lies; Michels, Evi et al

Poster (2015, June 01)

At this time, many wastes are used or eliminated through processes that do not really consider their potential applications. Such wastes contain useful nutrients (nitrogen, phosphorus and potassium), the ... [more ▼]

At this time, many wastes are used or eliminated through processes that do not really consider their potential applications. Such wastes contain useful nutrients (nitrogen, phosphorus and potassium), the importance of which has been demonstrated in agriculture for many years. The composition of wastes is highly heterogeneous, which makes treatment techniques more difficult to apply on a large scale. Sewage sludge is usually used as a fertilizer in agriculture, in energy production or in the field of construction. The main use of manure is agriculture, although considerable amounts of nutrients are lost and cause pollution. Digestate is also used in agriculture, but other alternatives have been proposed. Ashes should also be highlighted, although they do not contain nitrogen, which is lost into the atmosphere during the combustion process. Finally, household and industrial wastes are resources that should be considered as well. Those different types of wastes could be recycled to produce environment-friendly fertilizers. Here, we propose to investigate these opportunities inside five European countries (Belgium, France, Germany, United Kingdom and The Netherlands) through five work packages with the BioRefine Project. [less ▲]

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See detailDe la périménopause à la ménopause, quel intérêt d'un examen biologique
BELIARD, Aude ULg

in Revue de la Médecine Générale (2015), 324

Do hormonal blood tests provide support to the management of perimenopause? Should there be a systematic biological assessment before initiating hormonal therapy and to help monitoring it?

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See detailLinking political discourses on science with an evolving and densely populated context: Exploring the prospects of Cultural Political Economy
Charlier, Nathan ULg

Conference (2015, June)

As a PhD student, I investigate the multiple ways science is conceived and valued in a research and innovation (R&I) policy context under seismic shifts (Tyfield, 2012): I aim at analyzing and comparing ... [more ▼]

As a PhD student, I investigate the multiple ways science is conceived and valued in a research and innovation (R&I) policy context under seismic shifts (Tyfield, 2012): I aim at analyzing and comparing the various political discourses about R&I in Flanders and Wallonia (the two main regions of Federal Belgium). With regards to that goal, I am currently in the process of analyzing a corpus of 33 semi-structured interviews with principal investigators of two University biotech research centers, with members of two University research management boards, and with representatives of two regional science policy advisory boards. In order to analyze this particular set of discourses, I build on various sensitizing concepts (van den Hoonard 1997) such as policy narratives (Radaelli, 2000), while following the tenets of Grounded Theory (Glaser & Strauss, 1967). However, it is, I believe, necessary to connect the specific discourses I am studying to a broader context made of institutions, of actors engaged in power relationships, of policies and policy reforms, of a specific history, of other discourses, etc. The way one build ties between a particular set of data and broader contextual aspects is key to a fruitful sociological analysis. My proposal is to explore the potentialities offered by Cultural Political Economy (Sum & Jessop, 2013), an approach concerned with “the relation between semiosis and structuration in political economy” (Sum & Jessop, 2013: X), when trying to link discourses on R&I to the context they are part of. Acknowledging the “interdependence and co-evolution of the semiotic and extra-semiotic” (ibid., 23), CPE offers heuristic tools to study the articulation of specific discourses “with technologies and agency” (ibid., 20). My communication will disclose the iterative process of discourse analysis relying on CPE, as well as its results. [less ▲]

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See detailSuccessions internationales sous l'empire du Règlement 650/2012: Principes & planification
Wautelet, Patrick ULg

Conference given outside the academic context (2015)

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See detailAdjusted Equivalent Static Wind Loads for non-Gaussian linear static analysis
Blaise, Nicolas ULg; Denoël, Vincent ULg

Conference (2015, June)

In this paper, we propose a parametric bi-cubic model for the joint probability distribution of wind aerodynamic pressures and structural responses. This non-Gaussian model is a bivariate extension of the ... [more ▼]

In this paper, we propose a parametric bi-cubic model for the joint probability distribution of wind aerodynamic pressures and structural responses. This non-Gaussian model is a bivariate extension of the well-known Hermite polynomial transformation. It offers a new way to determine Equivalent Static Wind Loads, with the embedded feature to –at least partly– capture the non-Gaussianity of the aerodynamic pressures and responses. In a second step, based on the observation that this model as well as the usual LRC method or the conditional sampling technique, fail in reproducing structural responses that do not overestimate the extreme values resulting from a complete structural analysis, we propose a two-step adjustment procedure that restores the non-overestimation condition and the recovery of the considered structural response. With the example of a boundary layer flow around a duo-pitched roof, it is demonstrated that the Equivalent Static Wind Loads, adjusted or not, obtained with the proposed model of non-Gaussian joint probability density function reconstruct the envelope of structural response more efficiently than with the other two techniques. [less ▲]

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See detailThe Mars discrete aurora: Mars Express observations and modeling.
Gérard, Jean-Claude ULg

Scientific conference (2015, June)

Summary of earlier work Detection of additional ultraviolet auroral events (nadir and limb) Concurrent SPICAM-­‐ASPERA 3 observations Model results Perspectives

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See detailTerrestrial OH nightglow measurements during the Rosetta flyby
Migliorini, A.; Gérard, Jean-Claude ULg; Soret, Lauriane ULg et al

in Geophysical Research Letters (2015), 42

We present a study of the terrestrial hydroxyl nightglow emissions observed with the Visible and Infrared Thermal Imaging Spectrometer on board the Rosetta mission. During these observations, the OH Δv  ... [more ▼]

We present a study of the terrestrial hydroxyl nightglow emissions observed with the Visible and Infrared Thermal Imaging Spectrometer on board the Rosetta mission. During these observations, the OH Δv = 1 and 2 sequences were measured simultaneously. This allowed investigating the relative population of the v = 1 to 9 vibrational levels by using both sequences. In particular, the relative population of the vibrational level v = 1 is determined for the first time from observations. The vibrational population decreases with increasing vibrational quantum number. A good agreement is found with a recent model calculation assuming multiquantum relaxation for OH(v) quenching by O2 and single-quantum relaxation for OH(v) by N2. [less ▲]

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See detailIntroduction: Palaeolithic stone tool hafting
Rots, Veerle ULg

Scientific conference (2015, June)

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See detailCharacteristics of Jupiter's auroral acceleration region
Ray, Licia; Gustin, Jacques ULg; Grodent, Denis ULg

Poster (2015, June)

Jupiter’s dynamic auroral region is the signature of magnetosphere-ionosphere coupling. The magnetospheric drivers of the emission are relatively well understood, yet the high-latitude characteristics of ... [more ▼]

Jupiter’s dynamic auroral region is the signature of magnetosphere-ionosphere coupling. The magnetospheric drivers of the emission are relatively well understood, yet the high-latitude characteristics of the interaction have not been measure in-situ. Ahead of Juno’s arrival next summer, we use HST STIS observations of Jupiter’s auroral emission to infer the location of Jupiter’s auroral acceleration region and the properties of the precipitating auroral electrons. We analyze two images of Jupiter’s northern emission, determining the precipitating electron energy and incident energy flux for the main aurora, Io spot, Ganymede footprint, and flare regions. The resulting relationships between energy flux and electron precipitation energy for the main auroral emission are compared to the theoretical relationship derived by Lundin & Sandahl [1978] for a range of auroral region locations, and temperatures and densities appropriate for the jovian system. [less ▲]

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See detailHubble Space Telescope observations of variation of the O I 135.6 nm/ O I 130.4 nm ratio in Ganymede’s atmosphere
Molyneux, P. M.; Nichols, J. D.; Bannister, N. P. et al

Poster (2015, June)

We present new high-sensitivity HST/COS measurements of the atmospheric O I 135.6 nm/ O I 130.4 nm ratio at Ganymede, which we show exhibits significant spatial and temporal variability. Specifically, the ... [more ▼]

We present new high-sensitivity HST/COS measurements of the atmospheric O I 135.6 nm/ O I 130.4 nm ratio at Ganymede, which we show exhibits significant spatial and temporal variability. Specifically, the ratios observed on Ganymede’s leading hemispheres vary between 2.14±0.03 and 2.67±0.02, while on the trailing hemisphere the ratios are observed to be between 0.98±0.02 and 1.53±0.03. These high-sensitivity observations increase the signal to noise of these measurements by an order of magnitude over previous HST/STIS observations of the same [1], thus confirming that the temporal variation suggested by these previous observations is real. The emissions are excited through electron-impact excitation of Ganymede’s oxygen atmosphere by electrons which are locally accelerated within its magnetosphere [2,3]. The variation in the ratio magnitude may be explained either by variations in the ratio of atomic to molecular oxygen in the atmosphere or by a change in the temperature of the electrons exciting the emissions. An increase in the proportion of molecular oxygen acts to increase the ratio, as does a cooler electron temperature.References [1] Feldman, P. D., McGrath, M. A., Strobel, D. F., Moos, H. W., Retherford, K. D. and Wolven, B. C., HST/STIS ultraviolet imaging of polar aurora on Ganymede, Astrophys. J., Vol. 535, pp. 1085-1090, 2000. [2] Hall, D. T., Feldman, P. D., McGrath, M. A. and Strobel, D. F., The far-ultraviolet oxygen airglow of Europa and Ganymede, Astrophys. J., Vol. 499, pp. 475-481, 1998. [3] Eviatar, A., Strobel, D. F., Wolven, B. C., Feldman, P. D., McGrath, M. A. and Williams, D. J., Excitation of the Ganymede ultraviolet aurora, Astrophys. J., Vol. 555, pp. 1013-1019, 2001. [less ▲]

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See detailSearch for Satellite Effects on Saturn's Auroras in Cassini UVIS Data
Pryor, Wayne; Espositio, Larry; Jouchoux, Alain et al

Poster (2015, June)

The Cassini Ultraviolet Imaging Spectrograph (UVIS) has been obtaining Saturn auroral images since 2004. We have previously reported instances when the main auroral oval brightened briefly in a quasi ... [more ▼]

The Cassini Ultraviolet Imaging Spectrograph (UVIS) has been obtaining Saturn auroral images since 2004. We have previously reported instances when the main auroral oval brightened briefly in a quasi-periodic fashion near the sub-Mimas longitude. Here we examine the large set of UVIS auroral images obtained from close range and high sub-spacecraft latitudes. We will plot the brightness of the individual auroral measurements (and binned auroral measurements) as a function of local time, and as a function of the location of Mimas and other moons to test for any correlations. Mimas, while a relatively small moon, exerts a strong influence on Saturn's ring system. Mimas creates the Cassini Division between the A and B rings and forces a non-circular shape to the outer edge of Saturn's B ring that is partially locked to Mimas phase. [less ▲]

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See detailIntroduction: vegetal, animal and mineral residues
Rots, Veerle ULg

Scientific conference (2015, June)

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See detailLes prix de traduction fabriquent-ils une image régulatrice du traducteur ?
Mogollon Zapata, Juan Manuel ULg; Valéry, Plouhinec

in Convergences francophones (2015), 2

Les prix de traduction participent à la fois aux luttes pour la détention d’un capital de consécration et à la construction de l’image publique du traducteur. Ils sont une excellente entrée pour mesurer ... [more ▼]

Les prix de traduction participent à la fois aux luttes pour la détention d’un capital de consécration et à la construction de l’image publique du traducteur. Ils sont une excellente entrée pour mesurer les discours qui circulent dans l’espace du livre sur le traducteur et sa pratique. Comment ces prix construisent-ils une image légitimante du traducteur ? Quels critères guident le choix des jurys et quels dispositifs discursifs les justifient ? Quelles retombées pour les traducteurs et l’image de la traduction en général ? À travers l’analyse de nombreux exemples, cet article cherche à établir la manière dont les prix de traduction produisent un discours légitimant sur la figure du traducteur qui contribue à la fabrication de son image. [less ▲]

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See detailThe mysteries of droplet birth in microfluidic cross junctions
Van Loo, Stéphanie ULg

Poster (2015, June)

In microfluidics flow focusing is widely used to produce water-in-oil droplets in microchannels at high frequency. Nevertheless, the scaling laws associated to droplet length, speed and frequency could ... [more ▼]

In microfluidics flow focusing is widely used to produce water-in-oil droplets in microchannels at high frequency. Nevertheless, the scaling laws associated to droplet length, speed and frequency could not be identified yet, owing to the large number of parameters involved (incl. complex geometry). We here present an experimental study of droplet formation in a microfluidic cross-junction with a minimum number of geometrical parameters. We mostly focus on the dripping regime. The formation sequence is decomposed in two steps, inflation and squeezing, that vary differently according to both water and oil flow rates. These variations reveal several insights about the fluid flows in both phases. From there we infer the scaling law that relates droplet volume and frequency to the Capillary number associated to each inlet flow rate. This law involves a minimum of fitting parameters. We finally discuss the influence of inlet control (flow rate vs. pressure) and surfactants on the formation dynamics. [less ▲]

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See detailTiers Secteur et transition énergétique : le cas des parcs éoliens coopératifs au Danemark et en Belgique
Bauwens, Thomas ULg

Scientific conference (2015, June)

Le degré de développement du secteur des coopératives d’énergie renouvelable varie énormément à travers l’Europe. Alors que le modèle coopératif est solidement établi dans certains pays, il demeure ... [more ▼]

Le degré de développement du secteur des coopératives d’énergie renouvelable varie énormément à travers l’Europe. Alors que le modèle coopératif est solidement établi dans certains pays, il demeure marginal dans d’autres. Le présent exposé compare deux pays qui se distinguent clairement à cet égard : le Danemark et la Belgique. Le Danemark est un pionnier de l’énergie éolienne. En outre, son système énergétique est caractérisé par une décentralisation avancée et une présence importante de coopératives. La Belgique, quant à elle, présente un secteur coopératif beaucoup moins développé, mais au potentiel de croissance prometteur. Ces différences résultent de plusieurs facteurs économiques, institutionnels et socioculturels. La présentation se concentre sur quatre aspects essentiels: les mécanismes de soutien à l’énergie renouvelable, les politiques de planification, l’attitude sociétale face au modèle coopératif et l’activisme énergétique local. La dernière partie de l’exposé tentera de savoir dans quelle mesure les enseignements tirés de ces deux cas peuvent être transposés au contexte français. [less ▲]

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