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See detailDark matter, édité -- J. Audouze et J. Tran Thanh Van
Manfroid, Jean ULg

in Ciel et Terre (1989), 105

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See detailThe Dark Side of Customer Participation: The Antecedents of Customer Participation Stress
Treger, Stephanie; Büttgen, Marion; Schumann, Jan Hendrik et al

Conference (2016, May)

Detailed reference viewed: 76 (1 ULg)
See detailThe dark side of the black caiman: spatial and temporal trophic niche variations
Caut, Stéphane; Bacques, Mathieu; François, Vincent et al

Poster (2016, April 05)

A floating scientific platform was built in the Kaw marshes (French Guiana) to study this unique and still unknown ecosystem. Preliminary research has shown this pond is seasonally colonized by a large ... [more ▼]

A floating scientific platform was built in the Kaw marshes (French Guiana) to study this unique and still unknown ecosystem. Preliminary research has shown this pond is seasonally colonized by a large population of black caimans and represents the most important breeding site for many rare bird species. At the top of the food web, the black caiman is the largest neotropical predator and a particularly threatened crocodilian species, which implies that they have a major structuring role within the swamp ecosystem. Our preliminary study during the dry and wet season revealed important seasonal variations in the structure of the Agami pond population and the temporal presence of large caimans during the wet season (rarely observed in the Kaw marshes). Thus, coupling isotopic analysis (controlled diet and field studies) and different monitoring approaches (behavioral, microchip marking and satellite Argos tracking), we aim to conduct a detailed study of the Agami pond black caiman population: (i) to study the structure of the population and its variation over time, (ii) to estimate the intra- and inter-annual movements of individual caimans and identify potential feeding, reproductive and nesting areas in the Kaw marsh and (iii) to estimate this top predator’s role on the marsh’s ecological functioning and survival throughout the year. For this purpose, we will compare different field periods during the wet and dry seasons characterized by different hydrological and ecological patterns. This new information will help predict species response to disturbance, which is a prerequisite to effective conservation plan management involving local people and wildlife administrations. Finally, by coupling Argos tracking and stable isotopes, we will collect significant and valuable data for future applications at a global scale. [less ▲]

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See detailDark Vador
Dozo, Björn-Olav ULg

Conference given outside the academic context (2015)

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See detailThe darkening of the Greenland ice sheet: trends, drivers, and projections (1981–2100)
Tedesco, M.; Doherty, S.; Fettweis, Xavier ULg et al

in Cryosphere (The) (2016), 10

The surface energy balance and meltwater production of the Greenland ice sheet (GrIS) are modulated by snow and ice albedo through the amount of absorbed solar radiation. Here we show, using space-borne ... [more ▼]

The surface energy balance and meltwater production of the Greenland ice sheet (GrIS) are modulated by snow and ice albedo through the amount of absorbed solar radiation. Here we show, using space-borne multispectral data collected during the 3 decades from 1981 to 2012, that summertime surface albedo over the GrIS decreased at a statistically significant (99 %) rate of 0.02 decade−1 between 1996 and 2012. Over the same period, albedo modelled by the Modèle Atmosphérique Régionale (MAR) also shows a decrease, though at a lower rate ( ∼ −0.01 decade−1) than that obtained from space-borne data. We suggest that the discrepancy between modelled and measured albedo trends can be explained by the absence in the model of processes associated with the presence of light-absorbing impurities. The negative trend in observed albedo is confined to the regions of the GrIS that undergo melting in summer, with the dry-snow zone showing no trend. The period 1981–1996 also showed no statistically significant trend over the whole GrIS. Analysis of MAR outputs indicates that the observed albedo decrease is attributable to the combined effects of increased near-surface air temperatures, which enhanced melt and promoted growth in snow grain size and the expansion of bare ice areas, and to trends in light-absorbing impurities (LAI) on the snow and ice surfaces. Neither aerosol models nor in situ and remote sensing observations indicate increasing trends in LAI in the atmosphere over Greenland. Similarly, an analysis of the number of fires and BC emissions from fires points to the absence of trends for such quantities. This suggests that the apparent increase of LAI in snow and ice might be related to the exposure of a "dark band" of dirty ice and to increased consolidation of LAI at the surface with melt, not to increased aerosol deposition. Albedo projections through to the end of the century under different warming scenarios consistently point to continued darkening, with albedo anomalies averaged over the whole ice sheet lower by 0.08 in 2100 than in 2000, driven solely by a warming climate. Future darkening is likely underestimated because of known underestimates in modelled melting (as seen in hindcasts) and because the model albedo scheme does not currently include the effects of LAI, which have a positive feedback on albedo decline through increased melting, grain growth, and darkening. [less ▲]

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See detailDarkness improves growth and delays necrosis in a nonchlorophyllous habituated sugarbeet callus: Biochemical changes
Kevers, Claire ULg; Bisbis, B.; Le Dily, F. et al

in In Vitro Cellular & Developmental Biology - Plant (1995), 31(2), 122-126

The transfer of light-cultured green normal (N) and white habituated (HNO) sugarbeet callus to darkness reduced the growth of N callus and improved growth and delayed necrosis in the HNO callus. The ... [more ▼]

The transfer of light-cultured green normal (N) and white habituated (HNO) sugarbeet callus to darkness reduced the growth of N callus and improved growth and delayed necrosis in the HNO callus. The decrease of dry matter of N callus under darkness was accompanied by a reduced content of carotenoids and by decreased CO2 fixation, which was compensated by an increased dependency on externally supplied sucrose. The levels of some organic nitrogen compounds such as glutamate, proline, and free polyamines were not affected by transfer to darkness of N or HNO callus. Darkness decreased ethylene emissions in both callus types. In the HNO callus, the sucrose growth dependency and the CO2 fixation were unaffected by darkness. Chlorophylls were absent both in light and darkness, whereas some carotenoids were accumulated in the HNO callus only in dark conditions. In another connection, a significant increase of peroxidase activity, which did not occur in the N callus, was induced by darkness in the HNO callus. A decreased content of thio-barbituric acid (TBA)-reactive substances was measured in the HNO callus transferred to darkness, whereas an increase was noticed in the N callus placed in the same conditions. These metabolic changes and the reduction of cellular damage in darkness revealed light-induced stress reactions leading to necrosis and to reduced growth of HNO callus. It appeared that darkness allowed the HNO callus to avoid the photooxidation stress. Therefore, the favorable effect of darkness on HNO growth might be explained by the suppression of photooxidative damage due to the absence of carotenoids. The higher peroxidase activity in the HNO callus maintained in darkness raised the problem of heme synthesis in this heterotrophic callus. © 1995 Society for In Vitro Biology. [less ▲]

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See detailDarkness promotes flowering in the absolute long-day requiring plant, Lolium temulentum L. Ceres
Périlleux, Claire ULg; Bernier, Georges ULg; Kinet, Jean-Marie

in Journal of Experimental Botany (1997), 48(307), 349--351

Vegetative plants of the long-day grass Lolium temulentum L. Ceres were exposed to threshold long days or light breaks. Protracted darkness given just afterwards clearly promoted flowering and was weakly ... [more ▼]

Vegetative plants of the long-day grass Lolium temulentum L. Ceres were exposed to threshold long days or light breaks. Protracted darkness given just afterwards clearly promoted flowering and was weakly inductive on its own. The promotive effect of darkness was restricted to floral induction since further apical development was weak. [less ▲]

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See detailDarwin en Antarctique: diversité et phylogénie
Wilmotte, Annick ULg

in Bulletin de la Société Royale des Sciences de Liège (2009), 78

In the first part, I imagine that Charles Darwin has visited Livingston Island in the Antarctic Peninsula. In the first part, our research on the cyanobacterial diversity in the region of the Belgian ... [more ▼]

In the first part, I imagine that Charles Darwin has visited Livingston Island in the Antarctic Peninsula. In the first part, our research on the cyanobacterial diversity in the region of the Belgian research station Princess Elisabeth is presented. [less ▲]

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See detailDarwin ground-based European nulling interferometer experiment (GENIE)
Gondoin, Philippe; Absil, Olivier ULg; Fridlund, C V Malcolm et al

in Traub, Wesley (Ed.) Interferometry for Optical Astronomy II (2003, February 01)

Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars and to characterize ... [more ▼]

Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars and to characterize their atmospheres. Darwin is conceived as a space "nulling interferometer" which makes use of on-axis destructive interferences to extinguish the stellar light while keeping the off-axis signal of the orbiting planet. Within the frame of the Darwin program, the European Space Agency (ESA) and the European Southern Observatory (ESO) intend to build a ground-based technology demonstrator called GENIE (Ground based European Nulling Interferometry Experiment). Such a ground-based demonstrator built around the Very Large Telescope Interferometer (VLTI) in Paranal will test some of the key technologies required for the Darwin Infrared Space Interferometer. It will demonstrate that nulling interferometry can be achieved in a broad mid-IR band as a precursor to the next phase of the Darwin program. The present paper will describe the objectives and the status of the project. [less ▲]

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See detailThe Darwin Ground-based European Nulling Interferometry Experiment
Gondoin, P.; Absil, Olivier ULg; Fridlund, M. et al

in Lacoste, H. (Ed.) GENIE - DARWIN Workshop - Hunting for Planets (2003, March 01)

Darwin is one of the most challenging space pro jects ever considered by the European Space Agency (ESA). Its principal ob jectives are to detect Earth-like planets around nearby stars and to characterise ... [more ▼]

Darwin is one of the most challenging space pro jects ever considered by the European Space Agency (ESA). Its principal ob jectives are to detect Earth-like planets around nearby stars and to characterise their atmospheres. Darwin is conceived as a space nulling interferometer" which makes use of on-axis destructive interferences to extinguish the stellar light while keeping the o -axis signal of the orbiting planet. Within the frame of the Darwin program, the European Space Agency (ESA) and the European Southern Observatory (ESO) intend to build a ground-based technology demonstrator called GENIE (Ground based European Nulling Interferometry Experiment). Such a ground-based demonstrator built around the Very Large Telescope Interferometer (VLTI) in Paranal will test some of the key technologies required for the Darwin Infrared Space Interferometer. It will demonstrate that nulling interferometry can be achieved in a broad mid-IR band as a precursor to the next phase of the Darwin program. The present paper will describe the ob jectives and the status of the project. [less ▲]

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See detailThe Darwin mission within ESA’s Cosmic Vision
Absil, Olivier ULg

Scientific conference (2007, July 03)

Durant cet exposé, je présenterai la mission Darwin telle que proposée à l'ESA par un groupe de scientifiques européens et internationaux. Darwin s'inscrit parfaitement dans le Thème 1 du programme Cosmic ... [more ▼]

Durant cet exposé, je présenterai la mission Darwin telle que proposée à l'ESA par un groupe de scientifiques européens et internationaux. Darwin s'inscrit parfaitement dans le Thème 1 du programme Cosmic Vision: "What are the Conditions for Planet Formation and the Emergence of Life?". Je présenterai le cas scientifique de Darwin, qui a pour but principal de détecter et caractériser des planètes habitables semblables à la Terre autour d'étoiles du voisinage solaire. En complément à ce volet axé sur la planétologie comparée et l'astrobiologie, le cas scientifique de Darwin comprend aussi un volet consacré à l'imagerie à haute résolution angulaire d'objets astrophysiques et extragalactiques de types variés. Je m'attarderai finalement sur les avancées obtenues récemment tant sur le design de la mission que sur les technologies associées, qui devraient permettre d'atteindre ces objectifs dans le cadre de la première mission "Large" du programme Cosmic Vision et dans une enveloppe budgétaire raisonnable. [less ▲]

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See detailDarwin---an experimental astronomy mission to search for extrasolar planets
Cockell, Charles S; Herbst, Tom; Léger, Alain et al

in Experimental Astronomy (2009), 23

As a response to ESA call for mission concepts for its Cosmic Vision 2015--2025 plan, we propose a mission called Darwin. Its primary goal is the study of terrestrial extrasolar planets and the search for ... [more ▼]

As a response to ESA call for mission concepts for its Cosmic Vision 2015--2025 plan, we propose a mission called Darwin. Its primary goal is the study of terrestrial extrasolar planets and the search for life on them. In this paper, we describe different characteristics of the instrument. [less ▲]

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See detailDarwin-A Mission to Detect and Search for Life on Extrasolar Planets
Cockell, C. S.; Léger, A.; Fridlund, M. et al

in Astrobiology (2009), 9(1)

The discovery of extrasolar planets is one of the greatest achievements of modern astronomy. The detection of planets that vary widely in mass demonstrates that extrasolar planets of low mass exist. In ... [more ▼]

The discovery of extrasolar planets is one of the greatest achievements of modern astronomy. The detection of planets that vary widely in mass demonstrates that extrasolar planets of low mass exist. In this paper, we describe a mission, called Darwin, whose primary goal is the search for, and characterization of, terrestrial extrasolar planets and the search for life. Accomplishing the mission objectives will require collaborative science across disciplines, including astrophysics, planetary sciences, chemistry, and microbiology. Darwin is designed to detect rocky planets similar to Earth and perform spectroscopic analysis at mid-infrared wavelengths (6-20 mum), where an advantageous contrast ratio between star and planet occurs. The baseline mission is projected to last 5 years and consists of approximately 200 individual target stars. Among these, 25-50 planetary systems can be studied spectroscopically, which will include the search for gases such as CO[SUB]2[/SUB], H[SUB]2[/SUB]O, CH[SUB]4[/SUB], and O[SUB]3[/SUB]. Many of the key technologies required for the construction of Darwin have already been demonstrated, and the remainder are estimated to be mature in the near future. Darwin is a mission that will ignite intense interest in both the research community and the wider public. [less ▲]

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See detailThe Darwin-GENIE Experiment: An ESA-ESO Partnership
Gondoin, Ph; Absil, Olivier ULg; Erd, C. et al

in Sembach, K. R.; Blades, J. C.; Illingworth, G. D. (Eds.) et al Hubble's Science Legacy: Future Optical/Ultraviolet Astronomy from Space (2003)

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See detailDarwin-GENIE: a nulling instrument at the VLTI
Gondoin, Philippe A; Absil, Olivier ULg; den Hartog, Roland H et al

in Traub, Wesley (Ed.) New Frontiers in Stellar Interferometry (2004, October 01)

Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars and to characterise ... [more ▼]

Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars and to characterise their atmospheres. Darwin is conceived as a space "nulling interferometer" which makes use of on-axis destructive interferences to extinguish the stellar light while keeping the off-axis signal of the orbiting planet. Within the frame of the Darwin program, the European Space Agency (ESA) and the European Southern Observatory (ESO) intend to build a ground-based technology demonstrator called GENIE (Ground based European Nulling Interferometry Experiment). Such a ground-based demonstrator built around the Very Large Telescope Interferometer (VLTI) in Paranal will test some of the key technologies required for the Darwin Infrared Space Interferometer. It will demonstrate that nulling interferometry can be achieved in a broad mid-IR band as a precursor to the next phase of the Darwin program. The instrument will operate in the L' band around 3.8 mum, where the thermal emission from the telescopes and the atmosphere is reduced. GENIE will be able to operate in two different configurations, i.e. either as a single Bracewell nulling interferometer or as a double-Bracewell nulling interferometer with an internal modulation scheme. [less ▲]

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See detailDarwin: required performance (invited)
Absil, Olivier ULg

Scientific conference (2007, December 06)

Detailed reference viewed: 10 (1 ULg)