Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailLa nuit et le jour. L'être, l'art, l'autre selon Lévinas
Steinmetz, Rudy ULg

in Voir (2002)

Detailed reference viewed: 5 (2 ULg)
Full Text
See detailLa "nuit étoilée" et le "triangle hyperéchogène péri-veineux hilaire", signes de torsion splénique à l'échographie?
Terradas Crespo, Emilia; Barthelemy, Nicolas ULg; Gommeren, Kris ULg et al

in Monde Vétérinaire (Le) : European Veterinary Magazine (2014), 147

Une splénomégalie avec des plages hypoéchogènes diffuses et de multiples lignes hyperéchogènes parallèles dans le parenchyme, appelé lacy pattern ou stary sky = nuit étoilée, est un signe ayant une haute ... [more ▼]

Une splénomégalie avec des plages hypoéchogènes diffuses et de multiples lignes hyperéchogènes parallèles dans le parenchyme, appelé lacy pattern ou stary sky = nuit étoilée, est un signe ayant une haute probabilité de torsion splénique à l’échographie. Un autre signe échographique a été décrit comme étant un signe encore plus fiable de torsion splénique aigue. Il s’agit du triangle hyperéchogène péri-veineux hilaire. Cependant, ces signes ne sont pas des signes pathognomoniques de torsion splénique à l’échographie. [less ▲]

Detailed reference viewed: 14 (2 ULg)
See detailNul n'est censé être ignoré par le(s) droit(s). Politiques d'accès au droit et à la justice en Belgique et en France
Lejeune, Aude ULg

Doctoral thesis (2010)

My PhD dissertation seeks to describe and explain legal aid policies and practices in Belgium and France. The main focus lies on the relation between the mobilization of law and the institutional contexts ... [more ▼]

My PhD dissertation seeks to describe and explain legal aid policies and practices in Belgium and France. The main focus lies on the relation between the mobilization of law and the institutional contexts in which lawyers provide legal aid. This approach allows me to highlight the formation of innovative social and political mobilizations of law. This process is linked with recent social policies’ and, more broadly, public policies’ transformations. In my dissertation I suggest to break the deadlock between two types of opposite explanations of lawyering for the poor. On the one hand, macro-sociological explanations of legal aid transformations in occidental societies identified several waves of legal programs with little differences between the studied countries. On the other hand, micro-sociological approaches focused on the commitment conditions and choices of lawyering for the poor and disadvantaged. I rather lay emphasize on legal aid actors’ constraints, opportunities and resources in order to highlight both structures and agencies in legal practice. The first part of my dissertation is dedicated to a comparative and socio-historical outline of the transformation process the legal aid programs underwent in the past. During the second half of the 20th century the change of legal mobilizations and legal practices which target disadvantaged people correlated closely with the evolution of social policies. Particular attention is given to the progressive formation of non-professional groups, specialized in legal information and legal advice. I also analyze how these non-lawyers mobilize and refer to law. However, while innovative legal mobilization makes its appearance, old types of legal mobilization do not just vanish; this phenomenon makes legal mobilizations more diversified and complex. It also offers new opportunities for lawyers and non-lawyers to mobilize law in order to serve the disadvantaged. The examination of the lawyers and non lawyers’ strategies to be recognized as participants in legal aid policies constitutes the second part. I thereby analyze innovative social and political mobilizations of law how lawyers and local Bars attempt to preserve their professional jurisdiction as well as how non-legally-trained actors try to be recognized. The objective is to demonstrate empirically that the cooperation and the actors’ strategies can be fully understood by studying how lawyers and non-lawyers define legal mobilizations. Indeed, the actors’ main incertitude lies in defining which legal mobilizations are legitimate and which are not. The comparative approach of the thesis highlights peculiar national characteristics, particularly concerning the relationship among the State and “intermediate actors”, i.e. lawyers, Non-Governmental Organizations (NGOs) and, in France, local authorities (collectivités territoriales). In the legal aid sector, there are two models of governance. The French one relies on the delegation of social exclusion handling from the national state to NGOs and local authority. This process comes with a permanent control from the national state which seeks to preserve its authority to determinate policies in the legal sector. The Belgian one is based on the recognition of the lawyers’ activities by the State through a process I qualify as “mutual instrumentalization” between public authorities and intermediate actors. In the third part I analyze legal mobilizations in legal aid policies. Considering the translation of social problems into legal vocabulary as a political process, I contributed to the understanding of the relationship between lawyering and social change by underlying different ways of translations. Legal practices, professional belonging, and lawyers’ commitments are very heterogeneous. Nevertheless, I constructed a typology of legal mobilizations and legal practices. In a context where the transformation of social policies seeks to empower laypeople, lawyers are encouraged to intervene before litigations in order to pass “legal consciousness” on laypeople. Through this process, citizens could be able to defend and promote their rights in everyday life. In summary, my thesis underlines the tensions between the different kinds of legal mobilizations which refer to a specific definition of relationship between law and politics. [less ▲]

Detailed reference viewed: 136 (14 ULg)
Full Text
Peer Reviewed
See detailNull subspace-based damage detection of structures using vibration measurements
Yan, Ai-Min; Golinval, Jean-Claude ULg

in Mechanical Systems & Signal Processing (2006), 20(3), 611-626

A damage detection method of mechanical system based on subspace identification concepts and statistical process techniques is presented. The aim is to propose a method that is sensitive to small-sized ... [more ▼]

A damage detection method of mechanical system based on subspace identification concepts and statistical process techniques is presented. The aim is to propose a method that is sensitive to small-sized structural damages and suitable for on-line monitoring. Measured time-responses of structures subjected to artificial or environmental vibrations are assembled to form the Hankel matrix, which is further factorised by performing singular-value decomposition to obtain characteristic subspaces. It may be demonstrated that the structural responses are mainly located in the active subspace defined by the first principal components, which is orthonormal to the null subspace defined by the remaining principal components. If no structural damage occurs, the orthonormality relation between the subspaces remains valid with small residues when consecutive data sets are compared, and these residues may be evaluated by the proposed damage indicators. The method is validated using an experimental mock-up of an airplane subjected to different levels of damages simulated. It is also applied in environmental vibration testing of a street lighting device to monitor structural fatigue evolution. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 50 (5 ULg)
Full Text
See detailNull-Subspace Analysis for Structural Damage Monitoring in Fatigue Testing of Luminaires
Yan, Ai-Min; Marin, Frédéric; Golinval, Jean-Claude ULg

Conference given outside the academic context (2004)

A damage detection method of mechanical system based on output measurements only and on the subspace identification concept is presented. The method uses the definition of null subspace analysis of the ... [more ▼]

A damage detection method of mechanical system based on output measurements only and on the subspace identification concept is presented. The method uses the definition of null subspace analysis of the Hankel matrix. It is demonstrated to be sensitive to small-size structural damages and suitable for continuous on-line monitoring. The measured response records of structures under environmental or artificial vibrations are assembled in the Hankel matrix that is further factorized into special subspaces. The active subspace defined by the first principal components is shown to be orthonormal to the null subspace defined by the remaining principal components. Therefore, any evident increase of the residues signifies possible structural damages. The method is illustrated by an application to fatigue tests of a street lighting device (luminaires). Experimental methods and numerical calculations on luminaires are simply described and discussed. The test results show that the developed methods may be easily used to effectively monitor the damage evolution during the fatigue tests. [less ▲]

Detailed reference viewed: 39 (1 ULg)
See detailNulling Interferometry with IRSI-Darwin: Detection and Characterization of Earth-like Exoplanets
Absil, Olivier ULg

Scientific conference (2001, July 03)

The search for exoplanets has gained much interest since the first discovery of a planet orbiting the star 51 Peg by Mayor and Queloz in 1995. Current techniques for exoplanet detection, such as radial ... [more ▼]

The search for exoplanets has gained much interest since the first discovery of a planet orbiting the star 51 Peg by Mayor and Queloz in 1995. Current techniques for exoplanet detection, such as radial velocity measurements, are well suited to detect Jupiter-sized planets, but do not have enough sensitivity to discover planets similar to our Earth. The IRSI-Darwin space mission is aimed at filling this gap, by means of nulling interferometry. This special kind of interferometry is intended to suppress all the light coming from a blinding star by means of destructive interference, in order to reveal the star’s potential planetary companions. Once the starlight has been properly cancelled, the thermal emission from zodiacal and exo-zodiacal dust clouds becomes the main obstacle to planet detection. Internal modulation is a recent technique devised to suppress such spurious signals. It relies on rapid modulation between the outputs of two nulling interferometers sharing the same telescopes. In the present work, a comprehensive investigation of possible configurations of a telescope array with internal modulation has been undertaken, leading to a number of new configurations. As compared to the current Darwin configuration, the sensitivity of the interferometer to the planetary signal has been improved by a factor of two, resulting in a fourfold speedup in the detection and characterization of exoplanets. The possibility of designing a nulling interferometer on ESO’s Very Large Telescope Interferometer as a technological prerequisite to Darwin is also considered. Signal-to noise calculations show that this instrument could be used to characterize exo-zodiacal clouds down to the 10-zodi level. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
See detailNulling Interferometry with IRSI-Darwin: Detection and Characterization of Earth-like Exoplanets
Absil, Olivier ULg

Master's dissertation (2001)

The search for exoplanets has gained much interest since the first discovery of a planet orbiting the star 51 Peg by Mayor and Queloz in 1995. Current techniques for exoplanet detection, such as radial ... [more ▼]

The search for exoplanets has gained much interest since the first discovery of a planet orbiting the star 51 Peg by Mayor and Queloz in 1995. Current techniques for exoplanet detection, such as radial velocity measurements, are well suited to detect Jupiter-sized planets, but do not have enough sensitivity to discover planets similar to our Earth. The IRSI-Darwin space mission is aimed at filling this gap, by means of nulling interferometry. This special kind of interferometry is intended to suppress all the light coming from a blinding star by means of destructive interference, in order to reveal the star's potential planetary companions. Once the starlight has been properly cancelled, the thermal emission from zodiacal and exo-zodiacal dust clouds becomes the main obstacle to planet detection. Internal modulation is a recent technique devised to suppress such spurious signals. It relies on rapid modulation between the outputs of two nulling interferometers sharing the same telescopes. In the present thesis, a comprehensive investigation of possible configurations of a telescope array with internal modulation has been undertaken, leading to a number of new configurations. As compared to the current {\sc Darwin} configuration, the sensitivity of the interferometer to the planetary signal has been improved by a factor of two, resulting in a fourfold speedup in the detection and characterization of exoplanets. The possibility of designing a nulling interferometer on ESO's Very Large Telescope Interferometer as a technological prerequisite to {\sc Darwin} has also been considered. Signal-to-noise calculations have shown that this instrument could be used to characterize exo-zodiacal clouds down to the 10-zodi level. [less ▲]

Detailed reference viewed: 74 (10 ULg)
Full Text
See detailNulling interferometry with IRSI-Darwin: further study of the aperture configurations
Absil, Olivier ULg

in Surdej, Jean; Swings, Jean-Pierre; Caro, Denise (Eds.) et al 36th Liège International Astrophysics Colloquium (2001)

After a brief introduction to nulling interferometry, we emphasize the limitations of this technique for the detection of exoplanets, and the need for internal modulation, a recent technique for fast ... [more ▼]

After a brief introduction to nulling interferometry, we emphasize the limitations of this technique for the detection of exoplanets, and the need for internal modulation, a recent technique for fast signal chopping. The principles of internal modulation are then discussed and illustrated with an example. Our contribution to the Darwin mission deals with the study of new aperture configurations using internal modulation. the best two configurations identified among an infinity of new possibilities are presented. As compared to the current Darwin configuration, the sensitivity to the planetary signal is improved by a factor of two, resulting in a fourfold speedup in the detection and characterization of exoplanets. [less ▲]

Detailed reference viewed: 14 (2 ULg)
Full Text
Peer Reviewed
See detailNulling interferometry: impact of exozodiacal clouds on the performance of future life-finding space missions
Defrere, Denis ULg; Absil, Olivier ULg; den Hartog, Roland et al

in Astronomy and Astrophysics (2010), 509

Earth-sized planets around nearby stars are being detected for the first time by ground-based radial velocity and space-based transit surveys. This milestone is opening the path towards the definition of ... [more ▼]

Earth-sized planets around nearby stars are being detected for the first time by ground-based radial velocity and space-based transit surveys. This milestone is opening the path towards the definition of missions able to directly detect the light from these planets, with the identification of bio-signatures as one of the main objectives. In that respect, both ESA and NASA have identified nulling interferometry as one of the most promising techniques. The ability to study distant planets will however depend on exozodiacal dust clouds surrounding the target stars. In this paper, we assess the impact of exozodiacal dust clouds on the performance of an infrared nulling interferometer in the Emma X-array configuration. For the nominal mission architecture with 2-m aperture telescopes, we found that point-symmetric exozodiacal dust discs about 100 times denser than the solar zodiacal cloud can be tolerated in order to survey at least 150 targets during the mission lifetime. Considering modeled resonant structures created by an Earth-like planet orbiting at 1 AU around a Sun-like star, we show that the tolerable dust density for planet detection goes down to about 15 times the solar zodiacal density for face-on systems and decreases with the disc inclination. The upper limits on the tolerable exozodiacal dust density derived in this study must be considered as rather pessimistic, but still give a realistic estimation of the typical sensitivity that we will need to reach on exozodiacal discs in order to prepare the scientific programme of future Earth-like planet characterisation missions. [less ▲]

Detailed reference viewed: 20 (3 ULg)
Full Text
Peer Reviewed
See detailNulling interferometry: performance comparison between Antarctica and other ground-based sites
Absil, Olivier ULg; Coudé Du Foresto, V.; Barillot, M. et al

in Astronomy and Astrophysics (2007), 475

Context: Detecting the presence of circumstellar dust around nearby solar-type main sequence stars is an important pre-requisite for the design of future life-finding space missions such as ESA's Darwin ... [more ▼]

Context: Detecting the presence of circumstellar dust around nearby solar-type main sequence stars is an important pre-requisite for the design of future life-finding space missions such as ESA's Darwin or NASA's Terrestrial Planet Finder (TPF). The high Antarctic plateau may provide appropriate conditions to perform such a survey from the ground. Aims: We investigate the performance of a nulling interferometer optimised for the detection of exozodiacal discs at Dome C, on the high Antarctic plateau, and compare it to the expected performance of similar instruments at temperate sites. Methods: Based on the currently available measurements of the atmospheric turbulence characteristics at Dome C, we adapt the GENIEsim software (Absil et al. 2006, A&A, 448, 787) to simulate the performance of a nulling interferometer on the high Antarctic plateau. To feed a realistic instrumental configuration into the simulator, we propose a conceptual design for ALADDIN, the Antarctic L-band Astrophysics Discovery Demonstrator for Interferometric Nulling. We assume that this instrument can be placed above the 30-m thick boundary layer, where most of the atmospheric turbulence originates. Results: We show that an optimised nulling interferometer operating on a pair of 1-m class telescopes located 30 m above the ground could achieve a better sensitivity than a similar instrument working with two 8-m class telescopes at a temperate site such as Cerro Paranal. The detection of circumstellar discs about 20 times as dense as our local zodiacal cloud seems within reach for typical Darwin/TPF targets in an integration time of a few hours. Moreover, the exceptional turbulence conditions significantly relax the requirements on real-time control loops, which has favourable consequences on the feasibility of the nulling instrument. Conclusions: The perspectives for high dynamic range, high angular resolution infrared astronomy on the high Antarctic plateau look very promising. [less ▲]

Detailed reference viewed: 52 (8 ULg)
Full Text
Peer Reviewed
See detailNulling interferometry: performance comparison between space and ground-based sites for exozodiacal disc detection
Defrere, Denis ULg; Absil, Olivier ULg; Coudé Du Foresto, V. et al

in Astronomy and Astrophysics (2008), 490

Context: Characterising the circumstellar dust around nearby main sequence stars is a necessary step in understanding the planetary formation process and is crucial for future life-finding space missions ... [more ▼]

Context: Characterising the circumstellar dust around nearby main sequence stars is a necessary step in understanding the planetary formation process and is crucial for future life-finding space missions such as ESA's Darwin or NASA's terrestrial planet finder (TPF). Besides paving the technological way to Darwin/TPF, the space-based infrared interferometers Pegase and FKSI (Fourier-Kelvin Stellar Interferometer) will be valuable scientific precursors. Aims: We investigate the performance of Pegase and FKSI for exozodiacal disc detection and compare the results with ground-based nulling interferometers. Methods: We used the GENIEsim software (Absil et al. 2006, A&A, 448, 787) which was designed and validated to study the performance of ground-based nulling interferometers. The software has been adapted to simulate the performance of space-based nulling interferometers by disabling all atmospheric effects and by thoroughly implementing the perturbations induced by payload vibrations in the ambient space environment. Results: Despite using relatively small telescopes (<=0.5 m), Pegase and FKSI are very efficient for exozodiacal disc detection. They are capable of detecting exozodiacal discs 5 and 1 time respectively, as dense as the solar zodiacal cloud, and they outperform any ground-based instrument. Unlike Pegase, FKSI can achieve this sensitivity for most targets of the Darwin/TPF catalogue thanks to an appropriate combination of baseline length and observing wavelength. The sensitivity of Pegase could, however, be significantly boosted by considering a shorter interferometric baseline length. Conclusions: Besides their main scientific goal (characterising hot giant extrasolar planets), the space-based nulling interferometers Pegase and FKSI will be very efficient in assessing within a few minutes the level of circumstellar dust in the habitable zone around nearby main sequence stars down to the density of the solar zodiacal cloud. These space-based interferometers would be complementary to Antarctica-based instruments in terms of sky coverage and would be ideal instruments for preparing future life-finding space missions. [less ▲]

Detailed reference viewed: 24 (3 ULg)
Full Text
Peer Reviewed
See detailNullité et réduction, note sous Rb. Gent, 4 février 2002
Biquet, Christine ULg

in Journal des Juges de Paix = Tijdschrift van de Vrederecters (2003)

Detailed reference viewed: 16 (10 ULg)
Full Text
Peer Reviewed
See detailNumber and relative size of thenar motor units estimated by an adapted multiple point stimulation method.
Wang, François-Charles ULg; Delwaide, Paul ULg

in Muscle & nerve (1995), 18(9), 969-79

An adapted multiple point stimulation (AMPS) method is described for estimating the number and relative size of thenar motor units. With this method, the median nerve was stimulated at various sites from ... [more ▼]

An adapted multiple point stimulation (AMPS) method is described for estimating the number and relative size of thenar motor units. With this method, the median nerve was stimulated at various sites from the wrist to the elbow. To avoid alternation, only two or three clearly identifiable surface-recorded motor unit action potentials (S-MUAPs) were recruited at each point by incremental stimulation. A total of 10 S-MUAPs, elicited from four to five distinct stimulation points, was used to calculate the average S-MUAP size. By dividing the maximum M-potential size by that value, a motor unit number estimate (MUNE) was derived. In 59 healthy volunteers, from 19 to 87 years old, the mean average S-MUAP size was 87 +/- 27.6 microV.ms and the mean MUNE was 278 +/- 113 motor units. When performed repeatedly, the results were reproducible. The number of motor units declined exponentially with age while average S-MUAP sizes increased only moderately. To assess the validity of the AMPS method, its results were correlated with those obtained using the F-response technique. The correlation coefficient was 0.83 (P < 0.001). [less ▲]

Detailed reference viewed: 6 (2 ULg)
Full Text
Peer Reviewed
See detailNumber and relative size of thenar motor units in ALS patients: application of the adapted multiple point stimulation method.
Wang, François-Charles ULg; Delwaide, Paul ULg

in Electroencephalography and Clinical Neurophysiology (1998), 109(1), 36-43

In the present study, the adapted multiple point stimulation (AMPS) method was first applied to median innervated thenar muscles in 22 amyotrophic lateral sclerosis (ALS) patients who did not received any ... [more ▼]

In the present study, the adapted multiple point stimulation (AMPS) method was first applied to median innervated thenar muscles in 22 amyotrophic lateral sclerosis (ALS) patients who did not received any treatment. In all patients, a motor unit number estimate (MUNE) and an average surface-recorded motor unit action potential (S-MUAP) size have been derived even if the denervation was severe; and the results were reproducible. The thenar MUNE was less than the normal lower limit for age in 17 patients, and the mean MUNE (67.1 +/- 90.6) was significantly different from that estimated in control subjects (263.3 +/- 116.8). The mean S-MUAP size in the 22 ALS patients was 352.9 +/- 328.4 microV x ms versus 94.1 +/- 30.3 microV x ms in healthy volunteers. A control AMPS was achieved in 8 patients after 2 and 6 months of a glutamate-release antagonist (riluzole) treatment. The mean loss of motor units, based on control thenar MUNEs realized after 6 months of treatment, was 53%. In conclusion, we propose AMPS as a manageable, reproducible and non-invasive procedure which permits one to quantify peripheral denervation and to appreciate the effectiveness of collateral reinnervation in ALS patients. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailNumber of iterations when comparing MLEM/OSEM with FBP
Seret, Alain ULg

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (2004), 45(12), 2125-2125

Detailed reference viewed: 56 (5 ULg)
Full Text
See detailThe number of structures compatible with any correlation function
Gommes, Cédric ULg

Conference (2013, July)

A two-point correlation function provides a crucial yet an incomplete characterization of a microstructure because distinctly different microstructures may have the same correlation function. We address ... [more ▼]

A two-point correlation function provides a crucial yet an incomplete characterization of a microstructure because distinctly different microstructures may have the same correlation function. We address here the microstructural degeneracy question: What is the number of microstructures compatible with a specified correlation function? We compute this degeneracy in the framework of reconstruction methods, which enables us to map the problem to the determination of ground-state degeneracies. Since the configuration space of a reconstruction problem is a hypercube on which a Hamming distance is defined, we can calculate analytically the energy profile of any reconstruction problem, corresponding to the average energy of all microstructures at a given Hamming distance from a ground state. The steepness of the energy profile is a measure of the roughness of the energy landscape associated with the reconstruction problem, which can be used as a proxy for the ground-state degeneracy. The relationship between this roughness metric and the ground-state degeneracy is calibrated using a Monte Carlo algorithm for determining the ground-state degeneracy of a variety of microstructures (e.g., realizations of hard disks and Poisson point processes at various densities), as well as with microstructures with a known degeneracy (e.g., single disks of various sizes and a particular crystalline microstructure). We show that our results can be expressed in terms of the information content of the two-point correlation functions. From this perspective, the a priori condition for a reconstruction to be accurate is that the information content, expressed in bits, should be comparable to the number of pixels in the unknown microstructure. We provide a formula to calculate the information content of any two-point correlation function, which makes our results directly applicable by other researchers in the field. [less ▲]

Detailed reference viewed: 12 (2 ULg)
See detailThe number of structures compatible with any given correlation function
Gommes, Cédric ULg

Scientific conference (2012)

Detailed reference viewed: 2 (0 ULg)