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See detailA mutliwavelength observational study of the non-thermal emission from O-type stars.
De Becker, Michaël ULg

Doctoral thesis (2005)

The present work is devoted to an observational multiwavelength study of the non-thermal emission of O-type stars. The non-thermal radio emission is believed to be synchrotron radiation, therefore ... [more ▼]

The present work is devoted to an observational multiwavelength study of the non-thermal emission of O-type stars. The non-thermal radio emission is believed to be synchrotron radiation, therefore requiring the existence of a magnetic field as well as of a population of relativistic electrons. The physical circumstances responsible for the acceleration of electrons up to relativistic velocities are not yet completely elucidated, but such an acceleration most probably occurs through the first order Fermi mechanism in the presence of hydrodynamic shocks, also called the Diffusive Shock Acceleration (DSA) mechanism. In the context of massive stars, the shocks responsible for this acceleration process may be intrinsic to their stellar winds, or arise from the collision between stellar winds in binary systems. In addition, the existence of non-thermal emission processes such as inverse Compton scattering suggests the possibility to detect a high-energy counterpart to the non-thermal emission observed in the radio domain. The objectives of this work are to (1) study the impact of the multiplicity on the non-thermal emission, (2) investigate the issue of the non-thermal emission of massive stars in the high-energy domain, and (3) discuss the possibility to constrain physical quantities such as the magnetic field strength through the study of these non-thermal emission processes. We investigate in detail several non-thermal emitting O-type stars, namely HD168112, HD167971, Cyg OB2 #8A, Cyg OB2 #9, and HD15558. For most of these targets, high quality XMM-Newton data are used in order to study their X-ray properties. In most case, the question of the multiplicity is also addressed through optical studies performed on the basis of data obtained with ground-based telescopes. The most intensive study is carried out on the Cyg OB2 region, for which we also obtained and analysed INTEGRAL data, in order to investigate the possible relation between the massive stars in Cyg OB2 and the unidentified EGRET source 3EG J2033+4118. In addition, high quality XMM-Newton data of the close massive binary HD159176 are also studied. Even though this latter target does not belong to the category of non-thermal radio emitters, its study unexpectedly turns out to be crucial in the context of this campaign as it might be the first O + O system likely to be classified as an n! on-thermal X-ray emitter. Considering our observational results, along with results from radio observations mainly coordinated by colleagues from the Royal Observatory of Belgium, we propose a general qualitative schematic view of the non-thermal emission from massive stars. First, it seems that the multiplicity plays a crucial role in the non-thermal emission processes. Second, we have found that the simultaneous detection of non-thermal radiation in the radio and X-ray (below 10.0 keV) domains is unlikely. Non-thermal radio emitters are indeed most probably binaries with periods longer than a few weeks, whilst only close binaries with periods of at most a few days may be non-thermal emitters in the soft X-ray domain. However, such a simultaneous detection is possible if the very hard X-rays or soft gamma-rays are considered, i.e. in a domain where the thermal emission from the colliding winds does not overwhelm the non-thermal emission. Moreover, it appears that the existence of non-thermal X-ray emitters without a non-thermal radio counterpart should be envisaged. Finally, the simultaneous detection of radio and high-energy non-thermal emissions is likely to lead to an indirect method to estimate the local magnetic field strength in the colliding-wind region of massive binaries. [less ▲]

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See detailVibration Testing and System Identification
Dimitriadis, Grigorios ULg

Scientific conference (2005, December 16)

This presentation is a summary of the recent activity of the Dynamics and Aeroelasticity Research Group of the University of Manchester on the subjects of Vibration Testing and System Identification.

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See detailStability domains, substrate-induced conformational changes, and hinge-bending motions in a psychrophilic phosphoglycerate kinase: A microcalorimetric study
Zecchinon, Laurent ULg; Oriol, A.; Netzel, U. et al

in Journal of Biological Chemistry (2005), 280(50), 41307-41314

The cold-active phosphoglycerate kinase from the Antarctic bacterium Pseudomonas sp. TACII18 exhibits two distinct stability domains in the free, open conformation. It is shown that these stability ... [more ▼]

The cold-active phosphoglycerate kinase from the Antarctic bacterium Pseudomonas sp. TACII18 exhibits two distinct stability domains in the free, open conformation. It is shown that these stability domains do not match the structural N- and C-domains as the heat-stable domain corresponds to about 80 residues of the C-domain, including the nucleotide binding site, whereas the remaining of the protein contributes to the main heat-labile domain. This was demonstrated by spectroscopic and microcalorimetric analyses of the native enzyme, of its mutants, and of the isolated recombinant structural domains. It is proposed that the heat-stable domain provides a compact structure improving the binding affinity of the nucleotide, therefore increasing the catalytic efficiency at low temperatures. Upon substrate binding, the enzyme adopts a uniformly more stable closed conformation. Substrate-induced stability changes suggest that the free energy of ligand binding is converted into an increased conformational stability used to drive the hinge-bending motions and domain closure. [less ▲]

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See detailExcited [70,l(+)] baryons in large N-c QCD
Matagne, Nicolas; Stancu, Floarea ULg

in Physics Letters B (2005), 631(1-2), 7-15

The masses of the positive parity [70, 0(+)] and [70, 2(+)] non-strange baryons are calculated in large N-c QCD by considering the most dominant operators in an 1/N-c expansion. The approach is based on ... [more ▼]

The masses of the positive parity [70, 0(+)] and [70, 2(+)] non-strange baryons are calculated in large N-c QCD by considering the most dominant operators in an 1/N-c expansion. The approach is based on the introduction of an excited core, obtained after the last particle (an excited quark) has been removed. Configuration mixing is neglected, for simplicity. Although being a sub-leading 1/Nc order, we find that the spin-spin interaction plays a dominant role in describing the data. The role of No operators is also pointed out. We show how the contribution of the linear term in Nc, of the spin-spin and of the spin-orbit terms vary with the excitation energy. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailLes Wallons à Versailles : Henri-Joseph Rutxhiel. Sculpteur du pouvoir entre Empire et Restauration
Etienne, Mary ULg

in Carpeaux, Carole (Ed.) Les Wallons à Versailles (2005)

Édité dans le cadre de la journée d'études "Les Wallons à Versailles" organisée par la Commission royale des Monuments, Sites et Fouilles, le 5 décembre 2007, au château de Versailles, cet ouvrage ... [more ▼]

Édité dans le cadre de la journée d'études "Les Wallons à Versailles" organisée par la Commission royale des Monuments, Sites et Fouilles, le 5 décembre 2007, au château de Versailles, cet ouvrage regroupe les communications scientifiques du colloque ainsi que l’histoire de grands acteurs wallons à travers deux siècles d'Histoire commune entre la France et la Wallonie. [less ▲]

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See detailContribution to an adapted physiotherapy in the hyperlaxity syndromes
Kaux, Jean-François ULg; Foidart-Dessalle, Marguerite ULg; Toussaint, Geoffrey ULg et al

in First Annual Congress (of the new style) of the Royal Belgian Society of Physical and Rehabilitation Medicine (RBSPRM) (2005, December 02)

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See detailPolarimetric Standard Stars Observed with FORS1 at ESO-VLT
Mason, E.; Bagnulo, S.; Szeifert, T. et al

in ASP Conference Series (2005, December 01), 343

A Paranal Observatory project aims to analyze all the polarimetric standard stars in use at FORS1 to both check they have a constant polarization signal and measure the instrumental polarization ... [more ▼]

A Paranal Observatory project aims to analyze all the polarimetric standard stars in use at FORS1 to both check they have a constant polarization signal and measure the instrumental polarization. Preliminary results for 3 standards in the FORS1 calibration plans are presented. [less ▲]

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See detailRS Cha, a spectroscopic binary system as a test of stellar physics modeling during the pre-main sequence phase
Alecian, E.; Catala, C.; Goupil, Marie-José et al

in SF2A-2005: Semaine de l'Astrophysique Francaise (2005, December 01)

New spectra of the PMS eclipsing binary RS Cha obtained with the GIRAFFE spectrograph at the SAAO, allowed us to measure the metallicity and new masses of both components of RS Cha. The system is ... [more ▼]

New spectra of the PMS eclipsing binary RS Cha obtained with the GIRAFFE spectrograph at the SAAO, allowed us to measure the metallicity and new masses of both components of RS Cha. The system is therefore observationally well constrained, and modelling both stars (both with masses around 1.8 M[SUB]o[/SUB]) at the same (young) age is a severe challenge for stellar evolutionary codes. We find no evidence that our models are deficient. However accurate detection of modes and measurements of periods of the recently discovered pulsations in both components are required to constrain more severely the physical description of PMS stellar models. [less ▲]

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See detailL'astronomie dans le monde
Manfroid, Jean ULg

Article for general public (2005)

Venus Express, Deux lunes de plus, Mira et les anneaux, Astéroïde 1998 SF36 Itokawa, Les montagnes de la création, NGC 1333

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See detailRessources humaines et marketing: un mariage stratégique
Robert, Jocelyne ULg

Article for general public (2005)

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See detailTour du monde de l'édition belge
Habrand, Tanguy ULg

Article for general public (2005)

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See detailEffects of BM-573, a thromboxane A(2) modulator on systemic hemodynamics perturbations induced by U-46619 in the pig
Tchana-Sato, Vincent ULg; Dogné, Jean-Michel ULg; Lambermont, Bernard ULg et al

in Prostaglandins & Other Lipid Mediators (2005), 78(1-4), 82-95

The aim of our study was to evaluate the effects of thromboxane A(2) (TXA(2)) agonist, U-46619, on systemic circulatory parameters in the pigs before and after administration of a novel TXA(2) receptor ... [more ▼]

The aim of our study was to evaluate the effects of thromboxane A(2) (TXA(2)) agonist, U-46619, on systemic circulatory parameters in the pigs before and after administration of a novel TXA(2) receptor antagonist and synthase inhibitor (BM-573). Twelve anesthetized pigs were randomly assigned in two groups: in Ago group (n=6), the animals received six consecutive injections of U-46619 at 30 min interval, while in Anta group (n = 6) they received an increasing dosage regimen of BM-573 10 min before each U-46619 injection. The effects of each dose of BM-573 on ex vivo platelet aggregation induced by arachidonic acid, collagen or ADP were also evaluated. Vascular properties such as characteristic impedance, peripheral resistance, compliance, arterial elastance were estimated using a windkessel model. Intravenous injections of 0.500 mg/ml of BM-573 and higher doses resulted in a complete inhibition of platelet aggregation induced by arachidonic acid. In the same conditions, BM-573 completely blocked the increase of arterial elastance, and stabilized both mean aortic blood pressure and mean systemic blood flow. In conclusion, BM-573 could therefore be a promising therapeutic approach in pathophysiological states where TXA(2) plays it main role in the increase of vascular resistance like in pathologies such as systemic hypertension. (c) 2005 Published by Elsevier Inc. [less ▲]

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See detailValLait - Perspective d’évolution du contrôle laitier en Wallonie (Belgique)
Abras, Sven; Gillon, Alain ULg; Bertozzi, Carlo et al

in 12ièmes Recontres Recherches Ruminants, Paris, les 7 et 8 Décembre 2005 (2005, December)

ValLait est un projet qui vise à optimaliser les valorisations des données récoltées via le contrôle laitier. Ces valorisations reposent sur une régression multiple (“BP”, pour “Best Prediction”) qui ... [more ▼]

ValLait est un projet qui vise à optimaliser les valorisations des données récoltées via le contrôle laitier. Ces valorisations reposent sur une régression multiple (“BP”, pour “Best Prediction”) qui permet d’estimer les productions journalières de lait, de matières grasses et de protéines d’un animal en se basant sur différents effets comme le stade de lactation, la date de vêlage, les historiques de production du troupeau et de la population... En outre, le modèle BP permet également, dès le début de la lactation d’un animal, de prédire ses productions journalières futures. [less ▲]

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See detailComparison of the Sensititre YeastOne and Fungitest methods with the NCCLS M27-A2 reference method for antifungal susceptibility testing of yeasts
Hayette, Marie-Pierre ULg; Kondarowski, E.; Melin, Pierrette ULg et al

Poster (2005, December)

Background: The recent introduction of Sensititre YeastOne, a colorimetric microdilution method that includes new antifungal agents has opened the field to MIC’s determination by an easy-to-perform method ... [more ▼]

Background: The recent introduction of Sensititre YeastOne, a colorimetric microdilution method that includes new antifungal agents has opened the field to MIC’s determination by an easy-to-perform method. The aim of this study was to compare this test with the NCCLS M27-A protocol and with Fungitest, a current routine method for yeasts susceptibility testing. Methods: Sensititre YeastOne method (Trek diagnostic), and the NCCLS M27-A2 were performed on 300 yeasts clinical isolates distributed as follow: 125 C. albicans, 273 non-albicans species. Four antifungal agents were tested by the reference method: amphotericine B (AmB), fluconazole (FZ), itraconazole (ITZ), and voriconazole (VOR). The reading of the Sensititre and NCCLS results was visually performed after 24 and 48 h respectively. The Fungitest (Biorad) method was applied on 121 among the 300 isolates and the reading was made after 24 to 48 h incubation time according to the positive control growth. Results: By the NCCLS method, the MICs50/MICs90 (µg/ml) were as follows: 1/2 (AmB); 16/64 (FZ); 0.25/4 (ITZ) and 0.125/2 (VOR). Sensititre vs. NCCLS: The overall agreement within 2 dilutions for AmB, FZ, ITZ and VOR was respectively 54, 82, 80 and 78%. The MICs50/MICs90 were in absolute concordance for VOR by both techniques. Very major errors (%) were recorded as follows: 0.01/0 (AmB with a MIC ≥ 4/8µg/ml for resistant strains respectively), 1.6 (FZ), 3.6 (ITZ) and 2.3 (VOR with a MIC ≥ 8µg/ml for resistant strains). Fungitest vs. NCCLS: The agreement between both methods including minor discrepancies was 98% (AmB), 88% (FZ) and 98% (ITZ). Following the breakpoints given by the manufacturer, very major errors were 6.3% for FZ, 0.03% for ITZ and none for AmB. Conclusions: Sensititre is a convenient alternative to the NCCLS method for yeast susceptibility testing. Fungitest in spite of good correlations must change the breakpoints and include new antifungal agents to be competitive. [less ▲]

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See detailEULAR report on the use of ultrasonography in painful knee osteoarthritis. Part 1: Prevalence of inflammation in osteoarthritis
D'Agostino, M. A.; Conaghan, P.; Le Bars, M. et al

in Annals of the Rheumatic Diseases (2005), 64(12), 1703-1709

Objectives: To assess the prevalence of inflammation in subjects with chronic painful knee osteoarthritis (OA), as determined by the presence of synovitis or joint effusion at ultrasonography (US); and to ... [more ▼]

Objectives: To assess the prevalence of inflammation in subjects with chronic painful knee osteoarthritis (OA), as determined by the presence of synovitis or joint effusion at ultrasonography (US); and to evaluate the correlation between synovitis, effusion, and clinical parameters. Methods: A cross sectional, multicentre, European study was conducted under the umbrella of EULAR-ESCISIT. Subjects had primary chronic knee OA (ACR criteria) with pain during physical activity >= 30 mm for at least 48 hours. Clinical parameters were collected by a rheumatologist and an US examination of the painful knee was performed by a radiologist or rheumatologist within 72 hours of the clinical examination. Ultrasonographic synovitis was defined as synovial thickness >= 4 mm and diffuse or nodular appearance, and a joint effusion was defined as effusion depth >= 4 mm. Results: 600 patients with painful knee OA were analysed. At US 16 (2.7%) had synovitis alone, 85 (14.2%) had both synovitis and effusion, 177 (29.5%) had joint effusion alone, and 322 (53.7%) had no inflammation according to the definitions employed. Multivariate analysis showed that inflammation seen by US correlated statistically with advanced radiographic disease (Kellgren-Lawrence grade >= 3; odds ratio (OR) = 2.20 and 1.91 for synovitis and joint effusion, respectively), and with clinical signs and symptoms suggestive of an inflammatory "flare'', such as joint effusion on clinical examination (OR = 1.97 and 2.70 for synovitis and joint effusion, respectively) or sudden aggravation of knee pain (OR = 1.77 for joint effusion). Conclusion: US can detect synovial inflammation and effusion in painful knee OA, which correlate significantly with knee synovitis, effusion, and clinical parameters suggestive of an inflammatory "flare''. [less ▲]

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See detailControl of puberty by excitatory amino acid neurotransmitters and its clinical implications
Parent, Anne-Simone ULg; Matagne, V.; Bourguignon, Jean-Pierre ULg

in Endocrine (2005), 28(3), 281-285

Excitatory amino acids, glutamate in particular, have a marked stimulatory effect on the reproductive axis, particulary at puberty. Glutamate, N-methyl-D-aspartate (NMDA), and kainate stimulate ... [more ▼]

Excitatory amino acids, glutamate in particular, have a marked stimulatory effect on the reproductive axis, particulary at puberty. Glutamate, N-methyl-D-aspartate (NMDA), and kainate stimulate gonadotropin-releasing hormone (GnRH) secretion in immature mammals and NMDA receptor stimulation results in precocious puberty in rats and monkeys. Puberty is characterized by an increased sensitivity of GnRH to glutamate as well as an increase in glutaminase activity in the hypothalamus. Glutamatergic and GABAergic regulation of GnRH secretion seem strongly interdependent around puberty. in addition to the transsynaptic glutamatergic regulation of GnRH secretion, a coordinated activity of glutamatergic neurons and astroglial cells has been shown to play an active role in puberty. The participation of kainate receptors in the estradiol-induced advancement of puberty suggest that these receptors may be involved in the estradiol-mediated activation of GnRH secretion at puberty. A case of precocious puberty associated with hyperglycinemia illustrates the NMDA involvement in puberty in humans. in this patient, the occurrence of precocious puberty was thought to result from excessive stimulation by glycine of the NMDA receptors linked to the GnRH neurons. Glutamate plays several roles in the hypothalamic mechanism of puberty as it has been shown in animal models, but there are still few clinical data supporting the role of glutamate in human puberty. [less ▲]

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See detailIntegration de la pharmacogenetique dans la pratique medicale
Dideberg, Vinciane ULg; Bours, Vincent ULg

in Revue Médicale de Liège (2005), 60(12), 918-22

Today, the initiation of any medical treatment still raises questions about its efficacy and safety. Indeed, therapeutic responses vary over time and between individuals and are influenced by age, sex ... [more ▼]

Today, the initiation of any medical treatment still raises questions about its efficacy and safety. Indeed, therapeutic responses vary over time and between individuals and are influenced by age, sex, other treatments and the pathology itself. Genetic factors are thought to be responsible for 20 to 95% of these individual variations. Recent advances in biotechnology, molecular genetics and genomics allow a better understanding of drug metabolism and action. Pharmacogenetics, compiling phenotypic and genotypic data, may lead to a more personalized treatment. To allow a better approach of pharmacogenetics and pharmacogenomics, we will define these two terms and describe their actual and future clinical application. [less ▲]

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See detailPotential benefits of laparoscopic aorto-bifemoral bypass surgery
Rouers, Anthony; MEURISSE, Nicolas; LAVIGNE, Jean-Paul ULg et al

in Acta Chirurgica Belgica (2005), 105(6), 610-615

Background: This series aims to prove the positive impact of laparoscopic approach in aortofemoral bypass grafting. Methods : It concerns a retrospective non randomized study comparing 58 consecutive ... [more ▼]

Background: This series aims to prove the positive impact of laparoscopic approach in aortofemoral bypass grafting. Methods : It concerns a retrospective non randomized study comparing 58 consecutive patients treated with laparoscopic procedure (n = 30) and with a standard open procedure (n = 28) in a single center. The different operating times, the complications and the follow-up of these two groups are compared Results : The demographics and angiographic data of the two groups were comparable. Operating time was longer in the laparoscopic group. However, we noticed a significant shorter hospitalisation stay (p < 0.0001) after the laparoscopic procedure with a mean 5.1 days. There was no significant difference of morbidity. Conclusion : We suggest that the trans-peritoneal approach is the best way in laparoscopic procedure in term of exposure and ergonomics. Laparoscopic aortofemoral bypass grafting is feasible, safe and effective. Shortening of operating time is observed as surgeon's experience grows. [less ▲]

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See detailPatterns of physical activity determined by heart rate monitoring among diabetic children
Massin, M. M.; Lebrethon, M. C.; Brumioul, Danielle ULg et al

in Archives of Disease in Childhood (2005), 90(12), 1223-1226

Background: Children with type 1 diabetes should be encouraged to participate in physical activity because exercise can benefit insulin sensitivity and improve known risk factors for atherosclerosis ... [more ▼]

Background: Children with type 1 diabetes should be encouraged to participate in physical activity because exercise can benefit insulin sensitivity and improve known risk factors for atherosclerosis. Methods: Physical activity patterns of 127 children and adolescents with stable type 1 diabetes were investigated by 24 hour continuous heart rate monitoring. The percentage of heart rate reserve was used to measure the amounts of physical activity at different intensities. The results were compared with normative data. Results: Diabetic preschoolchildren accumulated 192.7 (78.1), 39.1 (24.3), and 21.3 (9.4) minutes/day (mean (SD)) of light, moderate, and vigorous physical activity, respectively. At the same activity levels, diabetic schoolchildren accumulated 168.9 (76.7), 37.9 (15.9), and 19.0 (14.8) minutes/day, and diabetic teenagers accumulated 166.3 (67.5), 45.6 (26.9), and 25.2 (15.3) minutes/day. Diabetic schoolchildren were significantly more active than healthy peers when considering moderate activity; diabetic teenagers were significantly more active when considering moderate and vigorous activity. There was a negative correlation between the most recent glycated haemoglobin and the time spent in light activities in schoolchildren, and a negative correlation between mean glycated haemoglobin for one year and time spent in light and moderate activities in schoolchildren. Conclusion: The majority of our diabetic patients meet the classical paediatric guidelines for physical activity and compare favourably with their healthy peers. [less ▲]

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