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See detailModes de rétroaction d’un bruit de fente en présence d’un résonateur
Billon, Alexis ULg; Valeau, Vincent; Sakout, Anas

Conference (2003, April)

La turbulence d’un jet produit, à bas nombre de Mach, un bruit de faible intensité de type large bande. Le niveau sonore est largement renforcé si on introduit un obstacle dans l’écoulement. Certaines ... [more ▼]

La turbulence d’un jet produit, à bas nombre de Mach, un bruit de faible intensité de type large bande. Le niveau sonore est largement renforcé si on introduit un obstacle dans l’écoulement. Certaines configurations géométriques, où une couche de cisaillement impacte sur un obstacle solide, produisent des sons harmoniques dits auto-entretenus, de forte intensité. Cet article concerne le bruit de fente (slot-tone), produit par l’impact d’un jet libre sur une plaque fendue. [less ▲]

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See detailNew methods for handling the range dependence of the clutter spectrum in non-sidelooking monostatic STAP radars
Lapierre, Fabian; Van Droogenbroeck, Marc ULg; Verly, Jacques ULg

in International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2003), Proceedings, Volume 5 (2003, April)

We address the problem of detecting slow-moving targets using a non-sideloking monostatic space-time adaptive processing (STAP) radar. The construction of optimum weights at each range implies the ... [more ▼]

We address the problem of detecting slow-moving targets using a non-sideloking monostatic space-time adaptive processing (STAP) radar. The construction of optimum weights at each range implies the estimation of the clutter covariance matrix. This is typically done by straight averaging of neighboring data snapshots. The range-dependence of these snapshots generally results in poor performance. We present two new methods that handle the rangedependence by exploiting the geometry of the direction-Doppler curves. [less ▲]

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See detailHormonosubstitution postmenopausique et risque de cancer mammaire: une mise a jour
van den Brule, F.; Lifrange, Eric ULg; Pintiaux, Axelle ULg et al

in Revue Médicale de Liège (2003), 58(4), 254-60

Numerous studies have examined the risk of breast cancer in patients with postmenopausal hormone substitution. Most of these studies are retrospective, and a few recent studies are prospective. The ... [more ▼]

Numerous studies have examined the risk of breast cancer in patients with postmenopausal hormone substitution. Most of these studies are retrospective, and a few recent studies are prospective. The observed results present with weak variations from baseline and major heterogeneity. Some studies highlight a slightly increased relative risk of breast cancer. A reanalysis of 51 studies demonstrates a relative risk of 1.35 for developing breast cancer during hormone substitution, with a 2.3% increased risk per year of use. Recently, the results of the WHI study have shown a slight increase of some risks of disease, including breast cancer (relative risk, 1.26). These results have induced the interruption of one of the 3 arms of the study (that of the patients treated with an estrogen-progestin combination), and have provoked a new discussion about the benefits and risks associated with hormone substitution. These facts have been largely related and commented in the general press. In this article, we review the important studies concerning this topic. [less ▲]

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See detailInfluence of the Aral Sea negative water balance on its seasonal circulation and ventilation patterns : use of a 3D hydrodynamic model
Sirjacobs, Damien ULg; Grégoire, Marilaure ULg; Delhez, Eric ULg et al

in Geophysical Research Abstracts (2003, April), 5(09052), 2003509052

Within the context of the EU INCO-COPERNICUS program "Desertification in the Aral Sea Region: A study of the Natural and Anthropogenic Impacts" (Contract IAC2-CT-2000-10023), a large-scale 3D hydrodynamic ... [more ▼]

Within the context of the EU INCO-COPERNICUS program "Desertification in the Aral Sea Region: A study of the Natural and Anthropogenic Impacts" (Contract IAC2-CT-2000-10023), a large-scale 3D hydrodynamic model was adapted to address specifically the macroscale processes affecting the Aral Sea water circulation and ventilation. The particular goal of this research is to simulate the effect of lasting negative water balance on the 3D seasonal circulation, temperature, salinity and water-mixing fields of the Aral Sea. The original Aral Sea seasonal hydrodynamism is simulated with the average seasonal forcings corresponding to the period from 1956 to 1960. This first investigation concerns a period of relative stability of the water balance, before the beginning of the drying process. The consequences of the drying process on the hydrodynamic of the Sea will be studied by comparing this first results with the simulation representing the average situation for the years 1981 to 1985, a very low river flow period. For both simulation periods, the forcing considered are the seasonal fluctuations of wind fields, precipitation, evaporation, river discharge and salinity, cloud cover, air temperature and humidity. The meteorological forcings were adapted to the common optimum one-month temporal resolution of the available data sets. Monthly mean kinetic energy flux and surface tensions were calculated from daily ECMWF wind data. Monthly in situ precipitation, surface air temperature and humidity fields were interpolated from data obtained from the Russian Hydrological and Meteorological Institute. Monthly water discharge and average salinity of the river water were considered for both Amu Darya and Syr Darya river over each simulation periods. The water mass conservation routines allowed the simulation of a changing coastline by taking into account local drying and flooding events of particular grid points. Preliminary barotropic runs were realised (for the 1951-1960 situation, before drying up began) in order to get a first experience of the behaviour of the hydrodynamic model. These first runs provide results about the evolution of the following state variables: elevation of the sea surface, 3D fields of vertical and horizontal flows, 2D fields of average horizontal flows and finally the 3D fields of turbulent kinetic energy. The mean seasonal salinity and temperature fields (in-situ data gathered by the Russian Hydrological and Meteorological Institute) are available for the two simulated periods and will allow a first validation of the hydrodynamic model. Various satellites products were identified, collected and processed in the frame of this research project and will be used for the validation of the model outputs. Seasonal level changes measurements derived from water table change will serve for water balance validation and sea surface temperature for hydrodynamics validation. [less ▲]

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See detailDossier en souffrance
Frankignoulle, Pierre ULg; Stevens, Barbara

in A+ (2003)

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See detailInheritance of sex in two ZZ pseudofemale lines of tilapia Oreochromis aureus
Desprez, D.; Mélard, Charles ULg; Hoareau, M. C. et al

in Aquaculture (2003), 218(1-4), 131-140

This paper reports a study on the sex determination system of the blue tilapia, Oreochromis aureus. Investigations were carried out using a pseudofemale line in two populations of O. aureus, known as ... [more ▼]

This paper reports a study on the sex determination system of the blue tilapia, Oreochromis aureus. Investigations were carried out using a pseudofemale line in two populations of O. aureus, known as Egyptian Population (EP) and Israel Population (IP). In O. aureus, males are the homogametic sex (ZZ/ZW), and sex reversal of fry with estradiol results in the production of some functional sex-reversed fish with a female phenotype and ZZ male genotype, known as pseudofemales or A-females. Crosses between ZZ pseudofemales and ZZ males theoretically should provide monosex ZZ male progeny only. We have studied the sex ratios of progeny from 43 IP (F-2 to F-3 generations) and 51 EP (F-1 to F-5 generations), pair-matings between normal males and pseudofemales. In IP, the male percentage in progenies ranged between 83% to 100% in F-2 and 66% to 100% in F-3. In EP, male percentage was more constant, varying from 88% to 100% in F-1, from 96% to 100% in F-3 and from 97% to 100% in F-5. In EP, F-2 and F-4 pseudofemales produced only monosex male progeny. This apparent difference in sex ratio frequency distributions between the two O. aureus pseudofemale lines could be due to the selection of males. EP pseudofemales were mated with their siblings for F-2 and F-3 pseudofemales or with closely related males for F-4 and F-5 pseudofemales. Conversely, IP pseudofemales were crossed with nonrelated males originating from research center broodstock, resulting in a higher proportion of females in sex ratio of progenies from successive generations of pseudofemales. The role of inbreeding is discussed in the context of predominantly monofactorial sex chromosome determination system operating in this species, influenced by other factors (genetic and environmental). The present study also shows that it is possible to fix the male sex determining factors (Z sex chromosome and genetic factors) in a line of pseudofemales, producing a high percentage of male progeny in five successive generations. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailModélisation de la répartition dynamique des produits phytopharmaceutiques sous une rampe de pulvérisation
Lebeau, Frédéric ULg

Doctoral thesis (2003)

A mathematical model aimed at estimating the distribution of spray deposits of phytopharmaceutical <br />products under a spray boom is proposed. It focuses on the need to take account of the dynamic ... [more ▼]

A mathematical model aimed at estimating the distribution of spray deposits of phytopharmaceutical <br />products under a spray boom is proposed. It focuses on the need to take account of the dynamic effects of <br />the forward movement of the boom. These are related both to the horizontal and vertical boom <br />movement and to the influence of aerodynamical factors on the nozzle spray distribution. <br />The model allows one to compute the spray deposits distribution by multiplying the nozzle spray <br />distribution by the time needed to move from one position to the next. Mathematically, this is expressed <br />by a convolution of the trajectory with the nozzle spray distribution. <br />The model is validated through a dynamic test bench aimed at reproducing the boom movements <br />observed in the field. The chosen method to measure spray deposits distribution is a chemical dosage of <br />the sprayed KCL solution collected in Petri dishes. This method is accurate if the spacing between <br />collectors is small enough. With constant speed and height, the longitudinal variability approaches 5 % <br />and the transversal spray deposits distribution is a function of the nozzle characteristics (as measured on <br />the static spray patternator) and of the nozzle speed. <br />A Pulse Width Modulation (PWM) nozzle boss fitted on the test bench is used to generate a dynamic <br />spray deposits distribution from which the dynamic bidimensional nozzle spray pattern is reconstructed. <br />This dynamic nozzle spray pattern introduced in the model allows a far better estimation of the spray <br />deposits distribution to be made than the one obtained using the static nozzle spray pattern computed <br />using filtered back-projection. <br />The use of the model for estimating the spray deposits distribution under a crop sprayer allows one <br />to identify the influential parameters and to calculate the dosages according to specific local <br />circumstances. Statistical parameters aimed at characterising the treatment quality are proposed. [less ▲]

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See detailDesign of the cryo-optical test of the PLANCK reflectors
Roose, Stéphane ULg; Cucchiaro, Antonio ULg; De Chambure, Daniel

Conference (2003, March 18)

PLANCK is the third Medium size mission of the ESA long-term scientific plan Horizon 2000. This paper present the current design status of the design of the cryo-optical test for the Planck primary ... [more ▼]

PLANCK is the third Medium size mission of the ESA long-term scientific plan Horizon 2000. This paper present the current design status of the design of the cryo-optical test for the Planck primary reflector and Planck secondary reflector [less ▲]

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See detailActivity-stability relationships in extremophilic enzymes
D'Amico, Salvino ULg; Marx, J. C.; Gerday, Charles ULg et al

in Journal of Biological Chemistry (2003), 278(10), 7891-7896

Psychrophilic, mesophilic, and thermophilic alpha-amylases have been studied as regards their conformational stability, heat inactivation, irreversible unfolding, activation parameters of the reaction ... [more ▼]

Psychrophilic, mesophilic, and thermophilic alpha-amylases have been studied as regards their conformational stability, heat inactivation, irreversible unfolding, activation parameters of the reaction, properties of the enzyme in complex with a transition state analog, and structural permeability. These data allowed us to propose an energy landscape for a family of extremophilic enzymes based on the folding funnel model, integrating the main differences in conformational energy, cooperativity of protein unfolding, and temperature dependence of the activity. In particular, the shape of the funnel bottom, which depicts the stability of the native state ensemble, also accounts for the thermodynamic parameters of activation that characterize these extremophilic enzymes, therefore providing a rational basis for stability-activity relationships in protein adaptation to extreme temperatures. [less ▲]

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See detailSolar Concentrator
Collette, Jean-Paul ULg; Defise, Jean-Marc ULg; Habraken, Serge ULg

Patent (2003)

A space solar concentrator based on light weight reflectors

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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 detailIMAGE FUV and in situ FAST particle observations of substorm aurorae
Mende, S. B.; Carlson, C. W.; Frey, H. U. et al

in Journal of Geophysical Research. Space Physics (2003), 108

Images from the IMAGE Wide-band Imaging Camera (WIC) and Spectrographic Imager (SI) channels SI-12 and SI-13 were compared to in situ data taken by FAST during several substorms. FAST spacecraft ... [more ▼]

Images from the IMAGE Wide-band Imaging Camera (WIC) and Spectrographic Imager (SI) channels SI-12 and SI-13 were compared to in situ data taken by FAST during several substorms. FAST spacecraft observations have shown that the high latitude auroral ionosphere has several distinct regions. Intense auroras are seen in regions of upward directed quasi static electric fields and of Alfven wave accelerated superthermal electrons. In two of the cases presented, the satellite passed through an active poleward propagating substorm surge on its duskward flank. Both show that the superthermal wave accelerated component to be on the polar cap boundary of the surge, and that it could be distinguished from quasi static field ``inverted V'' precipitation which occurred at the more equatorward parts of the auroral oval. In one of these cases, the surge was accompanied by intense ion outflow. Three cases showed the FAST satellite passing through the substorm aurora at midnight or the dawn side outside of the surge and the wave accelerated electrons were less clearly separated from the inverted V type precipitation. The wave accelerated electrons were seen to be part of very short-lived transient events, i.e., bursts. The region of auroral forms, associated with Alfven waves exhibit relatively soft auroral precipitation with very intense electron fluxes. By comparing the intensity of the WIC and SI-13 channels of IMAGE FUV, it is possible sometimes to distinguish optically between the two types of regions. Global imaging of the two regions would allow the separation of quasi-static plasma convection regions containing inverted V-s from regions of Alfven wave driven electrons signifying substorm related magnetic field dynamics. [less ▲]

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See detailGeographical traceabilitiy of food products.
Tychon, Bernard ULg; Oger, Robert ULg

Conference (2003, March)

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See detailIndividualisme, autonomie et dépendance dans la société contemporaine
Jacquemain, Marc ULg

Scientific conference (2003, March)

Du point de vue de la logique sociologique des conséquences inattendues, le papier tente de montrer que la véritable autonomie, comme le dit bien Richard Sennett, n'est de ne pas dépendre de personne (ce ... [more ▼]

Du point de vue de la logique sociologique des conséquences inattendues, le papier tente de montrer que la véritable autonomie, comme le dit bien Richard Sennett, n'est de ne pas dépendre de personne (ce qui définit la solitude ou l'exclusion), mais qu'elle se construit dans l'interdépendance mutuelle. L'article reprend et développe un des arguments esquissés dans "La Raison névrotique" [less ▲]

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See detailAnomalies du metabolisme osseux chez les patients infectes par le HIV et traites par tritherapie
GIOT, Jean-Baptiste ULg; Franchimont, N.; Moutschen, Michel ULg

in Revue Médicale de Liège (2003), 58(3), 155-63

For several years already, a growing number of studies reports modifications in the bone metabolism among HIV-infected patients. Some of these studies, published even before the use of HAART, involved the ... [more ▼]

For several years already, a growing number of studies reports modifications in the bone metabolism among HIV-infected patients. Some of these studies, published even before the use of HAART, involved the infection itself. With the experience already available as concerns HAART, antiretroviral treatments (ART) seem however to be called into question. Data are divergent yet. Some studies tend to invalidate the collected data about the harmful role of HAART and prove the absence of effect or even the beneficial action of ART on bone. Moreover, the three important classes of ART are implied, even if the proteases inhibitors are most commonly charged. Pathogenic mechanism remain hypothetical. While the impact on morbidity seems to be weak for the time being, long-term repercussions are still unknown, in particular when children are concerned. In such conditions, it appears difficult to set up coherent politics of screening, prevention and treatment. Nevertheless beyond the divergences, the multifactorial character of alteration of HIV-infected patient's bone metabolism seems to be undeniable. The identification of the different parameters should in the future clarify the situation and enable the publishing of exact criteria of screening, prevention and treatment. [less ▲]

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See detailGeneralized (m, k)-Zipf law for fractional Brownian motion-like time series with or without effect of an additional linear trend
Bronlet, Philippe ULg; Ausloos, Marcel ULg

in International Journal of Modern Physics C (2003), 14(3), 351-365

We have translated fractional Brownian motion (FBM) signals into a text based on two "letters", as if the signal fluctuations correspond to a constant stepsize random walk. We have applied the Zipf method ... [more ▼]

We have translated fractional Brownian motion (FBM) signals into a text based on two "letters", as if the signal fluctuations correspond to a constant stepsize random walk. We have applied the Zipf method to extract the zeta' exponent relating the word frequency and its rank on a log-log plot. We have studied the variation of the Zipf exponent(s) giving the relationship between the frequency of occurrence of words of length m < 8 made of such two letters: zeta' is varying as a power law in terms of m. We have also searched how the zeta' exponent of the Zipf law is influenced by a linear trend and the resulting effect of its slope. We can distinguish finite size effects, and results depending whether the starting FBM is persistent or not, i.e., depending on the FBM Hurst exponent H. It seems then numerically proven that the Zipf exponent of a persistent signal is more influenced by the trend than that of an antipersistent signal. It appears that the conjectured law zeta' = \2H - 1\ only holds near H = 0.5. We have also introduced considerations based on the notion of a time dependent Zipf law along the signal. [less ▲]

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See detailL'image du mois. Artere coronaire unique ou tronc commun occlus collateralise?
Gach, Olivier ULg; Troisfontaines, Paul ULg; Legrand, Victor ULg

in Revue Médicale de Liège (2003), 58(3), 117-8

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See detailConfigurations and Modulation Schemes Trade-off
Absil, Olivier ULg

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

During the preliminary phase A of the Ground-based European Nulling Interferometer Experiment (GENIE), a number of interferometric configurations have been studied, in the cases of exozodiacal cloud and ... [more ▼]

During the preliminary phase A of the Ground-based European Nulling Interferometer Experiment (GENIE), a number of interferometric configurations have been studied, in the cases of exozodiacal cloud and hot Jupiter detection. Their expected performances have been computed in light of the measured or expected performances of the VLTI subsystems. A simple Bracewell nulling interferometer, formed of two Unit Telescopes and working in the L’ or N bands, has been identified as a good candidate configuration for exozodiacal cloud detection. External or internal chopping, fringe tracking and intensity matching will be critical issues for this configuration. In the case of hot Jupiter detection, a double Bracewell with internal modulation in the L’ band seems well appropriate, and should allow to carry out low resolution spectroscopy on a few bright exoplanets. The basic assumptions and computations which have lead to these candidate configurations are described in this paper. [less ▲]

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See detailAnalysis of selected halogenated contaminants using SBSE-TD-PTV-GCxGC-IDTOFMS
Focant, Jean-François ULg; Sjodin; Needham et al

Poster (2003, March)

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See detailIsokinetic assessment of knee flexors and extensors in professional soccer players
Croisier, Jean-Louis ULg; Réveillon, Vincent; Ferret, J. M. et al

in Isokinetics & Exercise Science (2003, March), 11(1), 61-62

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