References of "2001"
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See detailTime-resolved laser spectroscopy of multiply ionized atoms: Natural radiative lifetimes in CeIV
Zhang, Z. G.; Svanberg, S.; Quinet, Pascal ULg et al

in Physical Review Letters (2001), 87(27),

Radiative lifetimes have been measured for two excited levels of Ce IV using the time-resolved laser-induced fluorescence technique. Ce3+ ions were produced in a laser-induced plasma. In the measurements ... [more ▼]

Radiative lifetimes have been measured for two excited levels of Ce IV using the time-resolved laser-induced fluorescence technique. Ce3+ ions were produced in a laser-induced plasma. In the measurements, a suitable magnetic field was applied to reduce the recombination between electrons and the ions and thus the background light from the recombination, and special care was exercised to avoid flight-out-of-view effects on the lifetime measurements for the high-velocity ions. The experimental lifetime results, tau = 30(2) ns for the level 49 737 cm(-1) and tau = 30(3) ns for the level 52 226 cm(-1), were compared with relativistic Hartree-Fock calculations (tau = 30.5 and 30.0 ns) indicating a particularly excellent agreement. [less ▲]

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See detailMeasurement of radiative lifetimes and determination of transition probabilities of astrophysical interest in HoIII
Biémont, Emile ULg; Palmeri, P.; Quinet, Pascal ULg et al

in Monthly Notices of the Royal Astronomical Society (2001), 328(4), 1085-1090

Lifetimes of six levels belonging to the 4f(10)6p configuration of Ho III have been measured for the first time using the time-resolved laser-induced fluorescence method. They are compared with ... [more ▼]

Lifetimes of six levels belonging to the 4f(10)6p configuration of Ho III have been measured for the first time using the time-resolved laser-induced fluorescence method. They are compared with multiconfigurational pseudo-relativistic Hartree-Fock calculations. A very good agreement is found. Using the experimental lifetimes and theoretical branching fractions, a first set of transition probabilities of astrophysical interest has been obtained for this ion. [less ▲]

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See detailEtude et modélisation du transport et du piégeage des solutés en milieu souterrain variablement saturé. Evaluation des paramètres hydrodispersifs par la réalisation et l'interprétation d'essais de traçage in situ
Brouyère, Serge ULg

Doctoral thesis (2001)

The long term protection of groundwater resources implies to study the behaviour of water and contaminants as soon as they penetrate in the underground (recharge) until they leave it at natural outlets ... [more ▼]

The long term protection of groundwater resources implies to study the behaviour of water and contaminants as soon as they penetrate in the underground (recharge) until they leave it at natural outlets (discharge in surface water bodies, springs, …) or at artificial extraction points (pumping wells, …). During this residence in the underground, many physical and chemical processes are likely to play a role on contaminant mobility. The attenuation, retardation and auto-purification capacities of the underground medium have thus to be quantified and considered. Consequences of their effect on contaminant behaviour can be positive (contaminant dispersion, dilution, degradation, …) or negative (difficulties to recover the contaminant, long-term impact of the contamination, …). This research aims at providing a conceptual and mathematical framework for studying on the field and for modelling the migration and retardation of solutes in variably saturated underground media. A classification of physico-chemical processes is proposed, based on three main criteria : (1) a differentiation between “microscopic” processes, playing a role at pore-scale and “macroscopic” processes, playing a role at field scale, (2) a distinction between physical processes (affecting any kind of contaminant, independently from its chemical nature) and chemical processes (affecting some contaminants, according to their specific chemical properties), (3) a distinction between equilibrium processes (independent of time) and kinetic processes (explicitly dependent of time). On that basis, the conceptual model includes three main compounds : advection, hydrodynamic dispersion and a mass exchange process between the mobile water and an immobile phase of aqueous (dual porosity effect) or solid (kinetic sorption) nature. Within this conceptual framework, developments and adaptations made in the SUFT3D code in order to model the behaviour of a contaminant in the variably saturated underground are presented. The evaluation of hydrodispersive parameters governing the migration and the capturing of contaminants relies on the interpretation of field tracer tests, conducted under variably saturated flow conditions. An important part of the research has thus been devoted to an improvement of tracer test techniques and interpretation, more particularly in terms of concentration and mass recovery evolutions, the latter being more appropriate for evaluation and quantification of retardation processes. In order to model more physically and accurately the tracer injection, a new conceptual, mathematical and numerical approach has been developed, considering explicitly well-aquifer interactions. Using this model, numerical tests show the impact of tracer injection conditions on tracer test results, possibly leading to wrong interpretation in terms of both processes identification and parameters quantification. In order to make a correct interpretation of tracer test results, the control of tracer injection conditions is thus essential. Two experimental studies illustrate the developments of this work. A multi-tracer test experiment was conducted under saturated conditions in the sediments of the alluvial plain of the river Meuse at Hermalle-sous-Argenteau. The results of these tests allow to validate and to illustrate the approach developed in order to model accurately tracer injection and well-aquifer interactions, to highlight other practical and conceptual problems encountered when conducting the experiments, to examine the chemical behaviour of several artificial tracers and to quantify the hydrodispersive properties of alluvial deposits. The objective of the second field experiment was to identify and to quantify solute migration mechanisms in the unsaturated zone overlying the chalk aquifer in the Hesbaye Region. These results allow to suggest a unifying conceptual and mathematical approach in order to represent the hydrodynamic and hydrodispersive properties of fissured chalk under variably saturated conditions. They also show the impact of physical properties of aeolian loess materials on their hydrodynamic properties. [less ▲]

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See detailDie Troianer in Metapont.
Morard, Thomas ULg

Scientific conference (2001, December 17)

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See detailFacies architecture and diagenesis of Belgian Late Frasnian carbonate mounds
Boulvain, Frédéric ULg

in Sedimentary Geology (2001), 145(3-4), 269-294

Late Frasnian Petit-Mont Member carbonate mounds occur in the southern pail of the Dinant Synclinorium and in the Philippeville Anticline (SW Belgium). These mounds are 30 to 80 m thick and 100 to 250 m ... [more ▼]

Late Frasnian Petit-Mont Member carbonate mounds occur in the southern pail of the Dinant Synclinorium and in the Philippeville Anticline (SW Belgium). These mounds are 30 to 80 m thick and 100 to 250 m in diameter. They are embedded in shale, nodular shale and argillaceous limestone. Based on facies mapping of 14 buildups and related off-mound sediments, these mounds typically started from below the photic and storm wave base zones and builtup into shallow water environments. Above an argillaceous limestone substrate, the first carbonate mound facies consists of spiculitic wackestone with stromatactis (PM1), which becomes progressively enriched in crinoids and corals (PM2), then in peloids, stromatoporoids and cyanobacteria (PM3). PM4 consists of algal-coral-peloid wackestone and packstone with green algae and thick algal coatings, A core of algal and microbial bindstone (PM5) sporadically occurs within large mounds. The uppermost part of these mounds may show a recurrence of facies PM2 and PM1. PM1 to PM3 are coloured red by hematite derived from microaerophilic iron bacteria; PM4 and PM5 are grey. The transition from the aphotic to the cyanobacterial photic zone is recorded in the succession PM2-PM3; the transition from the cyanobacterial to the green algal photic zone is recorded by PM3-PM5. Storm wave base was reached within PM3 and fair-weather wave base within PM5. This paleobathymetric interpretation suggests a depth of 100-150 in during initial establishment of PM1. Three types of mounds can be distinguished on the basis of geometry and facies architecture: (1) "Les Bulants"-type mounds display a continuous vertical facies succession (PM2-3-4-5) and low relief, (2) although exhibiting the same facies succession as "Les Bulants", "Les Wayons"-type mounds show a distinct relief with steep flanks and bioclastic talus; (3) "St.-Remy" mounds consist exclusively of PM1 and PM2, bioclastic flank deposits are not observed. From (1) to (3), these mound types represent successive deepening down a ramp. Biostratigraphic correlation on a regional scale provides good evidence that relative sea-level changes largely controlled lateral and vertical transitions of facies. Beyond that, hypoxic conditions are indicated by the sponge and iron-bacteria consortium in lower parts of the mounds. This is in agreement with the general assumption of stratified water masses during Late Frasnian, preceding the prominent Lower Kellwasser crisis. Cementation began with a radiaxial synsedimentary cement. A fringe of meteoric phreatic cement, initially nonluminescent, then with a bright orange luminescence, occurs in all mounds. It is contemporaneous with a nonluminescent pervasive cement of grainstones deposited in littoral areas. Differentiation between the (reducing) mounds and the (oxidizing) littoral area resulted from better aquifer circulation in sedimentary bodies close to the recharge area. Late burial cements occlude all the remaining porosity and are contemporaneous with the opening of the Variscan fracture system. (C) 2001 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailConcurrence et croissance: le point de vue d'un économiste
Gathon, Henry-Jean ULg

Conference given outside the academic context (2001)

Detailed reference viewed: 9 (4 ULg)
See detailComparative effect of hormone replacement therapy on bone mass density and skin tensile properties
Pierard, Gérald ULg; Vanderplaetsen, S.; Pierard-Franchimont, Claudine ULg

in Maturitas (2001), 40(3), 221-227

Objectives: connective tissues constitutive of skin and bones are affected during the climacteric. Hormone replacement therapy (HRT) can help mitigate their atrophy. The aim of this study was to compare ... [more ▼]

Objectives: connective tissues constitutive of skin and bones are affected during the climacteric. Hormone replacement therapy (HRT) can help mitigate their atrophy. The aim of this study was to compare the HRT effect on the skin tensile properties and bone mass density. Methods: a total of 120 postmenopausal women (60 untreated, 60 receiving HRT) were enrolled in the study. Skin tensile properties were assessed on the volar forearm using a computerized suction device. A 500 mbar suction was applied through a 4-mm diameter hollow probe. Two operating modes were applied using a steep and a progressive Suction, respectively. BMD was measured on the hip, femoral neck and lumbar spine using dual X-ray absorptiometry. Results: in both groups of women skin elasticity was correlated with BMD. HRT significantly reduced the climacteric-associated decline in skin elasticity. A trend in better preserved BMD was also found in these women without, however, reaching significance. Conclusions: it is concluded that measures of the skin tensile properties can be sensitive enough to disclose HRT efficacy upon connective tissue atrophy. Any decrease in skin elasticity during the climacteric should prompt to perform a BMD assessment. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved. [less ▲]

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See detailL'évolution du chlore inorganique au-dessus du Jungfraujoch et le Protocole de Montréal
Mahieu, Emmanuel ULg

Doctoral thesis (2001)

The main objective of this work was to determine the inorganic chlorine budget (Cly) at northern midlatitudes, to establish its variability and to study its temporal evolution over the last fifteen years ... [more ▼]

The main objective of this work was to determine the inorganic chlorine budget (Cly) at northern midlatitudes, to establish its variability and to study its temporal evolution over the last fifteen years. To achieve this, we have analyzed the observational database made of IR solar spectra recorded mainly with high resolution Fourier transform spectrometers installed at the International Scientific Station of the Jungfraujoch, located in the Swiss Alps, at 3580m altitude. The analysis of ATMOS (Atmospheric Trace Molecule Spectroscopy) data allowed us to first establish that HCl and ClONO2 account for more than 93% of the total inorganic chlorine, and that the summation of their vertical column abundances is an excellent surrogate of the Cly evolution at midlatitudes. Thus, we have derived HCl and ClONO2 total column abundance time series above the Jungfraujoch to analyze their temporal evolutions. Their combination has allowed us to show that the Cly increase between 1986 and 1995 (+50%) resulted primarily from the photodissociation of long-lived chlorinated source gas, in particular the manmade chlorofluorocarbons (CFC), progressively transported to the stratosphere after their release at the Earth surface during the seventies and the eighties. The organic chlorine (CCly) decrease in the troposphere resulting from regulations adopted by the Montreal Protocol, its Amendments and Adjustments, led to a progressive stabilization of Cly in the stratosphere. However, statistical analysis and interannual variability characterizing our time series, which extend to the end of 2000, prevent any final determination of the occurrence of the Cly maximum observed here at the end of October 1996, and of its subsequent decrease. We also show that chlorine partitioning among the chlorinated reservoirs has been durably influenced by heterogeneous processes which took place on stratospheric aerosols significantly enhanced following strong volcanic eruption of Mt Pinatubo (Philippines) in June 1991. The above-mentioned topics, complementary findings resulting from the study of the evolution of inorganic fluorine in the stratosphere, as well as comparisons other observational data bases and 2D model predictions are essentially discussed in Chapter 4. Before, Chapter 1 briefly reviews physical and chemical properties of the Earth atmosphere, and processes that control the state and erosion of stratospheric ozone. Individual contributions of chlorinated source gases to the CCly budget and their temporal evolution to the latter, inventory of Cly species, phase out schedule of chemical compounds covered by the Montreal Protocol and its Amendments and Adjustments are given in Chapter 2. Chapter 3 deals with instrumentation and data processing descriptions used to produce the geophysical data sets exploited in the main chapter of this work. [less ▲]

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See detailLe kimbanguisme : une "société" en mutation ?
Melice, Anne ULg

Conference (2001, December 13)

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See detailOptimalisation des apports en acides aminés pour des taurillons BBB en complément à une ration fermière
Beckers, Yves ULg; Froidmont, Eric

Conference (2001, December 12)

Detailed reference viewed: 23 (0 ULg)
See detailLe rein ischémié
Krzesinski, Jean-Marie ULg

Conference (2001, December 11)

Detailed reference viewed: 11 (0 ULg)
Peer Reviewed
See detail2-Alkyl-3-alkylamino-2H-benzo- and pyridothiadiazine 1,1-dioxides: Ca++ channel blockers rather than K+ATP channel openers?
De Tullio, Pascal ULg; Becker, B.; Ouedraogo, R. et al

Poster (2001, December 08)

Detailed reference viewed: 6 (0 ULg)
See detailEntre démographie et science politique: la définition du minoritaire et de la minorité
Martiniello, Marco ULg

Scientific conference (2001, December 03)

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See detailImportance of inbterspecific variation for designing conservation strategies in Plants : Centaurea jacea as case study
Vanderhoeven, Sonia ULg; Lefebvre, C.; Hardy, Olivier et al

Poster (2001, December 02)

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Peer Reviewed
See detailObservation of the proton aurora with IMAGE FUV imager and simultaneous ion flux in situ measurements
Gérard, Jean-Claude ULg; Hubert, Benoît ULg; Meurant, M. et al

in Journal of Geophysical Research. Space Physics (2001), 106(A12), 28939-28948

The far ultraviolet cameras on board the IMAGE satellite images the aurora in three different spectral regions. One of the channels of the spectrographic imager SI12 observes the Doppler-shifted Lyman ... [more ▼]

The far ultraviolet cameras on board the IMAGE satellite images the aurora in three different spectral regions. One of the channels of the spectrographic imager SI12 observes the Doppler-shifted Lyman alpha emission of precipitating protons. It makes it possible to spectrally discriminate between the proton and electron FUV aurora and to globally map the energetic protons. Its response depends on the auroral Lyman alpha. line shape which reflects the characteristics of the proton pitch angle and energy distributions. We illustrate the dependence of the SI12 count rate on the characteristic energy of the proton precipitation and the viewing geometry. Simultaneous in situ observations of the precipitated protons have been collected during a FAST satellite pass when IMAGE was observing the global north polar region. The premidnight region located at the equatorward boundary of the oval is dominated by proton precipitation with a mean energy E = 7 keV which is separated from the electron component. The prenoon crossing exhibits a softer proton energy spectrum with E = 0.9 keV. The measured proton energy distribution is used as an input to a Monte Carlo model to calculate the expected SI12 signal along the magnetic footprint of the satellite orbit. If the different spatial resolution of the two types of measurements is accounted for, a good quantitative agreement is found with the IMAGE observations. Similarly, ion flux measurements collected on board the Defense Meteorological Satellite Program F15 satellite during an overflight in the postmidnight sector provide good agreement with the SI12 observations at the footprint aurora. The comparisons confirm the reliability of the FUV IMAGE cameras to remotely discriminate between the electron and the proton precipitations. The vertical emission rate profiles of the N-2 Lyman-Birge-Hopfield and O I (1356 Angstrom) emissions are calculated in the proton-dominated premidnight region. It is shown that the protons and the electrons produce FUV emissions with contributions peaking at different altitudes. Excitation by secondary electrons dominates the production of both emissions. [less ▲]

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See detailChandra/ACIS observation of NGC 346
Nazé, Yaël ULg; Stevens, I. R.; Hartwell, J. et al

in Bulletin of the American Astronomical Society (2001, December 01)

The cluster NGC346 is the largest star formation region in the SMC. It contains a large fraction of the early-type O stars of this galaxy. In the outskirts of this cluster lies HD 5980, a unique system of ... [more ▼]

The cluster NGC346 is the largest star formation region in the SMC. It contains a large fraction of the early-type O stars of this galaxy. In the outskirts of this cluster lies HD 5980, a unique system of massive stars of which one component underwent a LBV-type eruption in 1993. The XMEGA consortium has obtained one deep (100 ks) Chandra exposure of NGC 346. It shows ~70 point sources, of which only half possess an optical counterpart; strong emission from HD 5980; and diffuse emission associated with the cluster and SNR 0057-7226. [less ▲]

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See detailDesign of the Heliospheric Imager for the STEREO mission
Defise, Jean-Marc ULg; Halain, Jean-Philippe ULg; Mazy, Emmanuel ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2001, December 01)

The Heliospheric Imager (HI) is part of the SECCHI suite of instruments on-board the two STEREO spacecrafts to be launched in 2005. The two HI instruments will provide stereographic image pairs of solar ... [more ▼]

The Heliospheric Imager (HI) is part of the SECCHI suite of instruments on-board the two STEREO spacecrafts to be launched in 2005. The two HI instruments will provide stereographic image pairs of solar coronal plasma and address the observational problem of very faint coronal mass ejections (CME) over a wide field of view (~90 degree(s)) ranging from 13 to 330 R[SUB]0[/SUB]. The key element of the instrument design is to reject the solar disk light, with straylight attenuation of the order of 10[SUP]-13[/SUP] to 10[SUP]-15[/SUP] in the camera systems. This attenuation is accomplished by a specific design of straylight baffling system, and two separate observing cameras with complimentary FOV's cover the wide FOV. A multi-vane diffractive system has been theoretically optimized to achieve the lower requirement (10[SUP]-13[/SUP] for HI-1) and is combined with a secondary baffling system to reach the 10[SUP]-15[/SUP] rejection performance in the second camera system (HI-2). This paper presents the design concept of the HI optics and baffles, and the preparation of verification tests that will demonstrate the instrument straylight performances. The baffle design has been optimized according to accommodation constrains on the spacecraft, and the optics were studied to provide adequate light gathering power and image quality. Straylight has been studied in the complete configuration, including the lens barrels and the focal plane assemblies. A specific testing facility is currently being studied to characterize the effective straylight rejection of the HI baffling. An overview of the developments for those tests is presented. [less ▲]

Detailed reference viewed: 28 (2 ULg)