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See detailOppositions et arguments paysagers dans le projet éolien en Wallonie
Vanderheyden, Vincent ULg; Schmitz, Serge ULg

Conference (2013, December 09)

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See detailOppositions locales et dynamiques d'environnementalisation
Mormont, Marc ULg; Bertrand, Anne

in Espaces et Sociétés (Paris, France) (2000), (101-102), 93-112

Local conflicts provoke collective action that through new coalitions induce reformulations of the problems and elarge scope and scaling of environmental problems. These processes are called ecologization ... [more ▼]

Local conflicts provoke collective action that through new coalitions induce reformulations of the problems and elarge scope and scaling of environmental problems. These processes are called ecologization dynamics and are going to transform environmental politics. [less ▲]

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See detailOPRs of Ammonia versus 14N/15N Ratios in CN in 15 Comets
Shinnaka, Yoshiharu; Kawakita, H.; Kobayashi, H. et al

in Bulletin of the American Astronomical Society (2010, October 01), 42

The solar system was formed from interstellar matter 4.6 Gyrs ago and comets are considered as remnants of icy planetesimals formed in the early solar system. One of interesting primordial characters of ... [more ▼]

The solar system was formed from interstellar matter 4.6 Gyrs ago and comets are considered as remnants of icy planetesimals formed in the early solar system. One of interesting primordial characters of cometary ice is an ortho-to-para abundance ratio (OPR) of molecules such as H2O, NH3, etc. The OPR probably indicates the molecular formation temperatures in the solar nebula or in the pre-solar molecular cloud. We determined the OPRs of ammonia by using the high dispersion optical spectra of NH2 in 15 comets: C/1995 O1 (Hale-Bopp), C/1999 S4 (LINEAR), C/2001 A2 (LINEAR), C/2000 WM1 (LINEAR), 153P/Ikeya-Zhang, C/2002 V1 (NEAT), C/2002 X5 (Kudo-Fujikawa), C/2002 Y1 (Juels-Holvorcem), C/2001 Q4 (NEAT), C/2002 T7 (LINEAR), C/2003 K4 (LINEAR), 8P/Tuttle, 88P/Howell, 9P/Tempel 1, and 73P-B and -C/Schwassmann-Wachmann 3. The observations were mainly carried out by the Ultraviolet and Visual Echelle Spectrograph (UVES) mounted on the Very Large Telescope (VLT) in Chile. Other telescopes/instruments were also used in some cases. The OPRs of ammonia are determined from OPRs of NH2 (0,9,0) ro-vibronic band around 600 nm. Although absorption lines (by the telluric atmosphere) and cometary C2 emission lines blended affected to NH2 emission lines in this region, we removed them in our analysis. The determined OPRs of ammonia clustered around 30K but not in the cases of 73P-B and -C. This situation is very similar to that of 14N/15N ratios in CN (i.e., 73P-B and -C are quite peculiar relative to other comets). We discuss about the relationship between the OPRs of ammonia and 14N/15N ratios in CN in these 15 comets. Our results indicate the formation of materials at relatively higher temperatures for 73P-B and -C than other comets. [less ▲]

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See detailOptic nerve sheath meningiomas
Litré, Claude Fabien ULg; Colin, P; Rousseaux, P et al

in Neuro-Chirurgie (2010), 56(2-3),

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See detailOptical analysis of particle size and chromite liberation from pulp samples of a UG2 ore regrinding circuit
Leroy, Sophie ULg; Dislaire, Godefroid; Bastin, David ULg et al

in Minerals Engineering (2011), 24

Since the early seventies high chromite and low base metal sulphide (BMS) contents of the UG2 reef imposes technological challenges to mineral processors and extractive metallurgists. Forty years later ... [more ▼]

Since the early seventies high chromite and low base metal sulphide (BMS) contents of the UG2 reef imposes technological challenges to mineral processors and extractive metallurgists. Forty years later, particle size distribution and size by size mineralogy are considered as key factors to the continuous improvement of the UG-2 ore metallurgy. With the successful development of ultra fine grinding technologies, a compromise has to be found between fine grinding to achieve platinum group minerals liberation and to avoid the overgrinding of gangue minerals, especially chromite gangue which is detrimental in smelting process. Indeed, fine chromite grains, despite of being naturally hydrophobic mineral, can be recovered in flotation concentrate by entrainment. In addition, overgrinding also increase liberation of naturally floatable gangue (talc) which contaminate the concentrate and need to be controlled during flotation. In this paper, innovative techniques of single particle image analysis from both dry and wet samples have been tentatively used to assess the chromite particle size distribution and the chromite grade of samples taken from a secondary milling circuit. Preliminary results demonstrate excellent potential for online particle imaging making use of both the particle geometry (size, shape) and the optical properties (translucency). [less ▲]

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See detailOptical and magnetic properties of Fe2+ and Cr2+ in II-VI semiconductors: The Jahn-Teller effect
Colignon, David ULg; Kartheuser, Eduard ULg; Rodriguez, Sergio et al

in Journal of Crystal Growth (1996), 159(1-4), 875-878

The D-5 terms of Fe2+ and Cr2+ in the tetrahedral potential at cation sites in II-VI compounds split into orbital doublet and triplet states. While in Cr2+ the orbital tripler has lower energy than the ... [more ▼]

The D-5 terms of Fe2+ and Cr2+ in the tetrahedral potential at cation sites in II-VI compounds split into orbital doublet and triplet states. While in Cr2+ the orbital tripler has lower energy than the doublet the opposite is the case in Fe2+. Both ions have singlet ground states after the spin-orbit interaction is taken into account and, hence, both are Van Vleck paramagnets. The optical absorption spectra of Fe and Cr based materials differ and are explained on the basis of a dynamic Jahn-Teller effect in the former and a static one in the latter. These considerations permit us to explain the optical as well as the magnetic properties observed in these materials. [less ▲]

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See detailOptical and mechanical design of a straylight rejection baffle for CoRoT
Plesseria, Jean-Yves ULg; Mazy, Emmanuel ULg; Defise, Jean-Marc ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2003, November 01)

The COROT mission is part of the program "Petites Missions" of CNES (French space agency). It implies international cooperation between France, Belgium, Germany, Austria, Spain and the European Space ... [more ▼]

The COROT mission is part of the program "Petites Missions" of CNES (French space agency). It implies international cooperation between France, Belgium, Germany, Austria, Spain and the European Space Agency (ESA). COROT aims to perform astroseismology measurements and to detect exoplanets. Long duration observations of stars will be used to detect periodic variations with an afocal telescope followed by a dioptric objective and 4 CCDs. Due to the orbit of the spacecraft (low altitude polar orbit) and even if the observation are performed in a direction perpendicular to orbit plane, the measurements can be disturbed by the straylight reflected on the earth (albedo) that can generate periodic perturbation. CSL is in charge of the design and procurement, with the help of Belgian industries, of a baffle and its protective cover that will be mounted on top of the afocal entrance telescope. The requirements are very stringent from the optical point of view as well as from the mechanical point of view. The rejection of the baffle must be of the order of 10[SUP]13[/SUP] for field angles above 20 degrees while the allocated mass is 19 kilograms. [less ▲]

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See detailOptical and structural characterization of TiO2 films doped with silver nanoparticles obtained by sol-gel method
Ivanova, T.; Harizanova, A.; Koutzarova, T. et al

in Optical Materials (2013), 36

Nanostructured titanium oxide films with incorporated Ag nanoparticles were deposited by sol-gel spin coating method. The films were annealed at 300 °C, 400 °C, 500 °C and 600 °C in oxygen and nitrogen ... [more ▼]

Nanostructured titanium oxide films with incorporated Ag nanoparticles were deposited by sol-gel spin coating method. The films were annealed at 300 °C, 400 °C, 500 °C and 600 °C in oxygen and nitrogen ambient. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV-VIS spectroscopy had been applied for studying the influence of the thermal treatments and the gas ambient on the structural and optical properties of TiO2 and TiO2:Ag films. The XRD analysis revealed the presence of metallic Ag phase without traces of silver oxides and these results were confirmed by FTIR spectra. It has been revealed that the annealing temperatures and the ambient, where the annealing is carried out is crucial for TiO2 crystallization, when there is Ag incorporation and especially for appearance of anatase and rutile phase. The nitrogen and oxygen ambient influences quite different the crystallization of TiO2:Ag films. Transmission and absorption spectra have been analyzed. Optical band gap values were evaluated for pure titania and Ag incorporated TiO2 films. © 2013 Elsevier B.V. All rights reserved. [less ▲]

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See detailOptical calibration of the FUV spectrographic imager for the IMAGE mission
Habraken, Serge ULg; Houbrechts, Yvette ULg; Renotte, Etienne ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (1999, October 01)

The FUV Spectrographic Imager for IMAGE is simultaneously imaging auroras at 1218 and 1358 angstrom. It is designed to efficiently reject the Lyman-(alpha) emission line at 1215.7 angstrom. This paper ... [more ▼]

The FUV Spectrographic Imager for IMAGE is simultaneously imaging auroras at 1218 and 1358 angstrom. It is designed to efficiently reject the Lyman-(alpha) emission line at 1215.7 angstrom. This paper describes the optical calibration. The content is: 1) field of view calibration: detector pixels location with respect to the reference optical cube; distortion matrix used to computer the TDI. b) Radiometric calibration: detector response and linearity; instrument throughput according to its clear aperture and mirror reflection lost; response vs. wavelength and band-rejection certification. [less ▲]

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See detailOptical circular polarisation of quasars
Sluse, Dominique ULg; Hutsemekers, Damien ULg; Cabanac, Remi et al

Conference (2012, October 16)

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See detailOptical circular polarization in quasars
Hutsemekers, Damien ULg; Borguet, Benoît ULg; Sluse, Dominique ULg et al

in Astronomy and Astrophysics (2010), 520(Letters), 71-5

We present new optical circular polarization measurements with typical uncertainties <0.1% for a sample of 21 quasars. All but two objects have null circular polarization. We use this result to constrain ... [more ▼]

We present new optical circular polarization measurements with typical uncertainties <0.1% for a sample of 21 quasars. All but two objects have null circular polarization. We use this result to constrain the polarization due to photon-pseudoscalar mixing along the line of sight. We detect significant (> 3σ) circular polarization in two blazars with high linear polarization and discuss the implications of this result for quasar physics. In particular, the recorded polarization degrees may be indicative of magnetic fields as strong as 1 kG or a significant contribution of inverse Compton scattering to the optical continuum. Based on observations made with ESO Telescopes at the La Silla Observatory (Chile). ESO program ID: 79.A-0625(B).Appendices are only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailOptical design of the FUV spectrographic imager for the IMAGE mission
Habraken, Serge ULg; Jamar, Claude ULg; Rochus, Pierre ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (1997)

This paper describes the original concept and the optical design of the IMAGE mission FUV spectrographic imager (SI). The instrument goal is to spectrally separate and image the electron and proton ... [more ▼]

This paper describes the original concept and the optical design of the IMAGE mission FUV spectrographic imager (SI). The instrument goal is to spectrally separate and image the electron and proton auroras. A 30 angstrom (3 nm) spectral resolution is required to isolate the electron auroras (1356 angstrom). The proton aurora imaging requires to efficiently mask the geocoronal Lyman-alpha line (1216 angstrom), in order to image the Doppler shifted Lyman-alpha light (1217 - 1223 angstrom). A classical SI combines a telescope with a spectrometer. Our SI is consisting of a reverse combination: (1) a multi-slits Wadsworth monochromator designed to spectrally isolate the two bandwidths (electrons and protons auroras), (2) a two mirror imager with a crossed delay line detector producing the final imaging on each spectral channel. [less ▲]

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