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See detailA Grassmann-Rayleigh quotient iteration for computing invariant subspaces
Absil, P.-A.; Mahony, R.; Sepulchre, Rodolphe ULg et al

in SIAM Review (2002), 44(1), 57-73

The classical Rayleigh quotient iteration (RQI) allows one to compute a one-dimensional invariant subspace of a symmetric matrix A. Here we propose a generalization of the RQl which computes a p ... [more ▼]

The classical Rayleigh quotient iteration (RQI) allows one to compute a one-dimensional invariant subspace of a symmetric matrix A. Here we propose a generalization of the RQl which computes a p-dimensional invariant subspace of A. Cubic convergence is preserved and the cost per iteration is low compared to other methods proposed in the literature. [less ▲]

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See detailEtude de l'effet de bordure dans les essais forestiers en milieu tropical
Fonton, H. N.; Claustriaux, Jean-Jacques ULg; Odjo, Th. et al

in Bulletin de la Recherche Agronomique du Bénin (2002), 35

The aim of this study is to examine the efficiency of border effect on the results analysis with the comparison of provenance and species of forest trees, it is recommended to take into account the border ... [more ▼]

The aim of this study is to examine the efficiency of border effect on the results analysis with the comparison of provenance and species of forest trees, it is recommended to take into account the border effect. Each plot has 49 trees (7 x 7); the border trees represent 49 % of the whole planted trees, and therefore 49 % of experimental unit. Twenty five essays were concerned with some repeated measurements. The experimental designs were randomized complete blocks and Latin square. The observed variables were total height and diameter at breast height. The analysis of variance showed that the differencies between plot sizes were not significant. We conclulde the use of small units under 49 trees to increase the number of repetitions and decrease the amount of the field work. [less ▲]

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See detailResistance testing in children changing human immunodeficiency virus type 1 protease inhibitor
Servais, Jean-Michel ULg; Hainaut, M.; Schmitz, V. et al

in Pediatric Infectious Disease Journal (2002), 21(3), 214-220

Objective. To assess genotypic and phenotypic resistance testing in HIV-1-infected children failing a first protease inhibitor (PI) therapy. Methods. In a multicenter observational study 21 children, ages ... [more ▼]

Objective. To assess genotypic and phenotypic resistance testing in HIV-1-infected children failing a first protease inhibitor (PI) therapy. Methods. In a multicenter observational study 21 children, ages 3 to 16 years, were given two reverse transcriptase inhibitors and one PI (mainly ritonavir, n = 18). They were subsequently treated with single or dual PI-based therapy (predominantly nelfinavir, n = 10, or ritonavir-saquinavir, n = 7). Resistance testing was performed at the time of therapy switch via direct sequencing and a recombinant virus susceptibility assay. Results. A total of 21 genotypic and 15 phenotypic resistance profiles were obtained. Most viruses displayed several reverse transcriptase mutations; however, 7 isolates maintained a wild-type protease. Ritonavir targeted the well-known pathway containing 82, 54, 46 and other secondary (nonactive site) mutations including T74A. No in vitro cross-resistance, i.e. greater than or equal to8-fold resistance to saquinavir or amprenavir, was encountered. Secondary mutations enhanced the prediction of ritonavir resistance (i.e. L10I) and in vitro nelfinavir cross-resistance (i.e. K20R/I conferred by primary (active site) resistance mutations. Either the 82, 54, 46 mutational genotype or the phenotype showing greater than or equal to8-fold nelfinavir cross-resistance predicted a poorer virologic response to nelfinavir salvage therapy. Conclusion. In a small cohort of heavily pretreated pediatric patients, resistance testing appears to predict the response to nelfinavir as salvage for a ritonavir-based therapy. This is further supported by the correlation between ritonavir-selected mutations and in vitro nelfinavir cross-resistance. Prospective studies should assess clinical outcome in children undergoing regimen changes based on resistance testing. [less ▲]

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See detailHeartburn in Belgium: prevalence, impact on daily life, and utilization of medical resources
Louis, Edouard ULg; DeLooze, D.; Deprez, P. et al

in European Journal of Gastroenterology & Hepatology (2002), 14(3), 279-284

Background Gastro-oesophageal reflux disease (GORD) is a frequently occurring disease that may be considered a public health issue, particularly in developed countries. The specificity of heartburn for ... [more ▼]

Background Gastro-oesophageal reflux disease (GORD) is a frequently occurring disease that may be considered a public health issue, particularly in developed countries. The specificity of heartburn for the diagnosis of GORD is good. Our aim was to define the prevalence of heartburn in Belgium, characterizing both its impact on everyday life and the ensuing use of medical resources. Methods Two thousand people living in Belgium, selected randomly after stratification, were interviewed face to face. The main question in the questionnaire used in this interview concerned the presence over the previous 12 months of a burning sensation in the epigastric and/or retrosternal region. This was followed by 21 secondary questions on the characteristics of the population studied, the impact of heartburn on everyday life, and the medical resources used. Results Twenty-eight per cent of the population interviewed reported heartburn. This symptom was present at least once a week in 42% of sufferers. Heartburn was more frequent in women than men (P < 0.05) and was not distributed uniformly throughout the various regions of the country (P < 0.05). Seventy-seven per cent of the people with heartburn found that it had a significantly negative impact on their daily lives (in 27%, this effect was strong). Heartburn associated with a substantial negative impact on daily life was characterized by a higher frequency of symptoms (P < 0.0001), a longer duration of the problem (P= 0.006), and the presence of pain (P < 0.0001) and anxiety (P < 0.0001). Fifty-six per cent of individuals with heartburn had already sought medical advice, 45% had undergone an upper-gastrointestinal tract endoscopy, and 59% were taking medications. Among patients complaining that heartburn had a substantial negative effect on their everyday lives, 21.6% had not sought medical advice and 22.2% did not take any medication. Conclusion Heartburn is very frequent in Belgium and is associated with a considerable negative impact on everyday life. It also generates a significant use of medical resources. However, among the patients complaining of a substantial negative effect on their daily lives, one-fifth (which would represent 1.5% of the Belgian population) seemed to lack appropriate care. [less ▲]

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See detailAn entropy based technique for information embedding in images
Van Droogenbroeck, Marc ULg; Delvaux, Jérôme

in IEEE Signal Processing Symposium, Proceedings (2002, March)

Many information hiding techniques have recently been analyzed as they could help manage part of the digital rights. Among the general framework of information hiding, the focus has been put on ... [more ▼]

Many information hiding techniques have recently been analyzed as they could help manage part of the digital rights. Among the general framework of information hiding, the focus has been put on steganography and on watermarking techniques. This paper proposes an entropy based technique for data embedding in images with a specific target, sometimes referred to as feature location: inclusion of a maximum amount of information instead of robustness against attacks. After an introduction, we analyze the error that results from a modification of the least significant bits. Then we describe our embedding technique. Finally we examine the upper bound of information that can be embedded in the least significant bits by means of our technique and we conclude. [less ▲]

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See detailFongicides en froment
Moreau, Jean-Marc; Bodson, Bernard ULg; Vancutsem, Françoise ULg

in Livre Blanc: Céréales - Gembloux (2002, February 27)

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See detailL'azote minéral du sol en 2001-2002 sous froment d'hiver
Bodson, Bernard ULg; Destain, Jean-Pierre ULg; Vancutsem, Françoise ULg et al

in Livre Blanc: Céréales - Gembloux (2002, February 27)

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See detailLes conseils de fumure azotée
Bodson, Bernard ULg; Destain, Jean-Pierre ULg; Vancutsem, Françoise ULg et al

in Livre Blanc: Céréales - Gembloux (2002, February 27)

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See detailEvolution du fractionnement de la fumure azotée
Bodson, Bernard ULg; Vancutsem, Françoise ULg; Falisse, André

in Livre Blanc: Céréales - Gembloux (2002, February 27)

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See detailCyclic esterketone compounds, processes for the synthesis thereof and process for the preparation of poly (esterketone) polymers
Wautier, Henri; Latere, Jean-Pierre; Lecomte, Philippe ULg et al

Patent (2002)

Unsubstituted oxepane-diones useful as monomers for the production of polymers, process for the synthesis thereof by oxidation of unsubstituted cyclohexanediones, process for the preparation of ... [more ▼]

Unsubstituted oxepane-diones useful as monomers for the production of polymers, process for the synthesis thereof by oxidation of unsubstituted cyclohexanediones, process for the preparation of polyesterketone polymers by polymerization of cyclic esterketones and polyesterketone polymers so obtained. [less ▲]

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See detailSodium nitrite and ascorbic acid: a metal-free combination that controls the free-radical polymerization of tert-butyl methacrylate in water
Detrembleur, Christophe ULg; Mouithys-Mickalad, Ange ULg; Teyssié, Philippe et al

in e-Polymers (2002), (4), 1-16

A mixture of sodium nitrite and ascorbic acid is able to control the radical polymerization of tert-butyl methacrylate (tBMA) in water at 80°C. Indeed, sodium nitrite is reduced by the ascorbic acid, and ... [more ▼]

A mixture of sodium nitrite and ascorbic acid is able to control the radical polymerization of tert-butyl methacrylate (tBMA) in water at 80°C. Indeed, sodium nitrite is reduced by the ascorbic acid, and the nitric oxide (NO) which is formed in situ is nothing but a promoter of nitroxyl radicals. The radical polymerization of tBMA is thus basically controlled by a nitroxide-mediated process. [less ▲]

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See detailLithiation of toluene by organolithium compounds activated by lithium polyether alkoxides
Nugay, Nihan; Nugay, Turgut; Jérôme, Robert ULg et al

in Journal of Molecular Catalysis A: Chemical (2002), 179(1-2), 59-64

The catalytic effect of polyether alkoxides (PEAs) on the activity of organolithium. compounds as metallating agent has been investigated. Toluene has been lithiated by using different organolithiums ... [more ▼]

The catalytic effect of polyether alkoxides (PEAs) on the activity of organolithium. compounds as metallating agent has been investigated. Toluene has been lithiated by using different organolithiums activated by various PEAs. It has been found that n-BuLi, yields higher conversion with 100% benzylic position metallation, whereas sec-BuLi gives some metallation at ring positions with the most reactive ligand, lithium 2-methoxy ethoxide (LiOEM). Optimum PEA to organolithium molar ratio for both sec- and n-BuLi activated by LiOEM where the amount of toluene being kept constant, was found to be as 3:1 with highest yield and regioselectivity. Substantial increment in yield was observed when the amount of substrate increased whereas regioselectivity stayed almost constant. It was also found that, for a constant reactant molar ratio (3:1:15) for which the optimum results were achieved, reaction began early and then yield values increased with time whereas upon increase in reaction temperature from -78 to 20degreesC, the benzylic metallation yield increased drastically while keeping the same regioselectivity high. [less ▲]

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See detailA study of noncovalent interactions by electrospray mass spectrometry
Gabelica, Valérie ULg

Doctoral thesis (2002)

This work describes a study of noncovalent interactions by electrospray mass spectrometry (ES-MS). In particular, we studied DNA duplexes, DNA complexes with drugs and cyclodextrin complexes with ... [more ▼]

This work describes a study of noncovalent interactions by electrospray mass spectrometry (ES-MS). In particular, we studied DNA duplexes, DNA complexes with drugs and cyclodextrin complexes with aliphatic acids. ES-MS experiments were performed on a hybrid quadrupole-TOF instrument and on an ion trap instrument. Basically two kinds of information can be obtained on the complexes. First, the full scan mass spectra give information on the composition of the solution that is injected, and therefore on the solution-phase stability of the complexes. We compare the ESMS data with the solution-phase data, and discuss the specificity of the observed complexes. The problem of nonspecific aggregation was encountered for the hydrophobic cyclodextrin complexes. We developed a new method for determining simultaneously the equilibrium association constant of [1:1] complexes and the ratio between the electrospray response factors of the complex and the free substrate. A change in the substrate conformation upon ligand binding can be detected by measuring the response factors of the complex and the free host. Second, the collision-induced dissociation of the complexes in the gas phase and the measurement of the amounts of fragments resulting from this dissociation give information on the gas phase kinetic stability of the complexes. It is shown that different collision regimes allow the system to fragment via different pathways, and that fast activation conditions favor the noncovalent dissociation of the complex because this process is entropy favored. The gas-phase kinetic stability measurements on series of homologous complexes suggest that intermolecular interactions like hydrogen bonding, electrostatic interactions, and stacking are conserved in the gas phase. Finally, on the basis of the results obtained on DNA duplexes, we propose a general multistep mechanism for the dissociation of noncovalent complexes. [less ▲]

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See detailM1/E2 transition rates in Fe x through Fe XIII measured at a heavy-ion storage ring
Trabert, E.; Gwinner, G.; Wolf, A. et al

in Journal of Physics B-Atomic Molecular and Optical Physics (2002), 35(3), 671-689

The rates of several electric-dipole forbidden decays of 3p and 3d levels in Cl-, S-, P- and Si-like ions of Fe have been measured optically at a heavy-ion storage ring. In several cases, more than one ... [more ▼]

The rates of several electric-dipole forbidden decays of 3p and 3d levels in Cl-, S-, P- and Si-like ions of Fe have been measured optically at a heavy-ion storage ring. In several cases, more than one decay contributes to a given decay curve, which complicates the analysis. The lifetime results, with a precision range from 0.6 to 20%, compare well with some theoretical predictions, but are more precise. They are also more precise than some experimental data from an electrostatic ion trap. [less ▲]

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See detailPituitary disease in MEN type 1 (MEN1): Data from the France-Belgium MEN1 multicenter study
Vergès, B.; Boureille, F.; Goudet, P. et al

in Journal of Clinical Endocrinology and Metabolism (2002), 87(2), 457-465

To date, data on pituitary adenomas in MEN type 1 (MEN1) still have to be evaluated. We analyzed the data of a large series of 324 MEN1 patients from a French and Belgian multicenter study. Data on ... [more ▼]

To date, data on pituitary adenomas in MEN type 1 (MEN1) still have to be evaluated. We analyzed the data of a large series of 324 MEN1 patients from a French and Belgian multicenter study. Data on pituitary disease were compared with those from 110 non-MEN1 patients with pituitary adenomas, matched for age, year of diagnosis, and follow-up period. Genetic analysis of the MEN1 gene was performed in 197 of the MEN1 patients. In our MEN1 series, pituitary disease occurred in 136 of 324 (42%), less frequently than hyperparathyroidism (95%, P < 0.001) and endocrine enteropancreatic tumors (54%, P < 0.01). Mean age of onset of pituitary tumors was 38.0 +/- 15.3 yr (range, 12-83 yr). Pituitary disease was associated with hyperparathyroidism in 90%. of cases, with enteropancreatic tumors in 47%, with adrenal tumors in 16%, and with thoracic neuroendocrine tumors in 4%. Pituitary disease was the initial lesion of MEN1 in 17% of all MEN1 patients. MEN1 pituitary adenomas were significantly more frequent in women than in men (50% vs. 31%,P < 0.001). Among the 136 pituitary adenomas, there were 85 prolactinomas and 12 GH-secreting, 6 ACTH-secreting, 13 cosecreting, and 20 nonsecreting tumors. Eighty-five percent of MEN1-related pituitary lesions were macroadenomas (vs. 42% in non-MEN1 patients, P < 0.001), including 32% of invasive cases. Among secreting adenomas, hormonal hypersecretion was normalized, after treatment, in only 42% (vs. 90% in non-MEN1 patients, P < 0.001), with a median follow-up of 11.4 yr. No correlation was found between the type of MEN1 germ-line mutation and the presence or absence of pituitary adenoma. Our study, based on a large group of MEN1 patients, shows that pituitary adenomas occur in 42% of the cases and are characterized by a larger size and a more aggressive presentation than without MEN1. [less ▲]

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See detailCampagne de mesure des odeurs sur le CET de Mont-Saint-Guibert Mise au point d'une méthode d'estimation des nuisances
Nicolas, Jacques ULg

Report (2002)

The study is made in the frame of a follow-up monitoring of all landfill sites in Wallonia, initiated by the Ministry of Environment and managed by ISSeP. The research group applied a field inspection ... [more ▼]

The study is made in the frame of a follow-up monitoring of all landfill sites in Wallonia, initiated by the Ministry of Environment and managed by ISSeP. The research group applied a field inspection technique based on the perception of a panel of experts sniffing the air around the region of interest and trying to delineate the odour plume. In a second step, the recorded meteorological data are entered into an atmospheric dispersion model and the odour emission rate of the facility is adjusted until the predicted odour impact zone fits about exactly the one which is measured in the field. The present report is the first one of a long series of measurement campaigns. It presents in details the used methodology and the results of the study. [less ▲]

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See detailLaisse tomber le C8 ... je pars au Chili! (1)
Nazé, Yaël ULg

Article for general public (2002)

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See detailAn optical time-delay for the lensed BAL quasar HE 2149-2745
Burud, I.; Courbin, F.; Magain, Pierre ULg et al

in Astronomy and Astrophysics (2002), 383(1), 71-81

We present optical V and i-band light curves of the gravitationally lensed BAL quasar HE 2149-2745. The data, obtained with the 1.5 m Danish Telescope (ESO-La Silla) between October 1998 and December 2000 ... [more ▼]

We present optical V and i-band light curves of the gravitationally lensed BAL quasar HE 2149-2745. The data, obtained with the 1.5 m Danish Telescope (ESO-La Silla) between October 1998 and December 2000, are the first from a long-term project aimed at monitoring selected lensed quasars in the Southern Hemisphere. A time delay of 103+/-12 days is determined from the light curves. In addition, VLT/FORS1 spectra of HE 2149 2745 are deconvolved in order to obtain the spectrum of the faint lensing galaxy, free of any contamination by the bright nearby two quasar images. By cross-correlating the spectrum with galaxy-templates we obtain a tentative redshift estimate of z = 0.495+/-0:01. Adopting this redshift, a Omega = 0.3, Lambda = 0.7 cosmology, and a chosen analytical lens model, our time-delay measurement yields a Hubble constant of H-0 = 66+/-8 km s(-1) Mpc(-1) (1sigma error) with an estimated systematic error of +/-3 km s(-1) Mpc(-1). Using non-parametric models yields H-0 = 65+/-8 km s(-1) Mpc(-1) (1sigma error) and confirms that the lens exhibits a very dense/concentrated mass profile. Finally, we note, as in other cases, that the flux ratio between the two quasar components is wavelength dependent. While the flux ratio in the broad emission lines-equal to 3.7-remains constant with wavelength, the continuum of the brighter component is bluer. Although the data do not rule out extinction of one quasar image relative to the other as a possible explanation, the effect could also be produced by differential microlensing by stars in the lensing galaxy. [less ▲]

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See detailFrequency domain approaches for the identification of an experimental beam with a local nonlinearity
Kerschen, Gaëtan ULg; Golinval, Jean-Claude ULg

in 20th International Modal Analysis Conference, Los Angeles, 2002 (2002, February)

Two approaches for the identification of multi-degree-of-freedom non-linear systems in the frequency domain have recently been introduced, i.e., the conditioned reverse path (CRP) method and the non ... [more ▼]

Two approaches for the identification of multi-degree-of-freedom non-linear systems in the frequency domain have recently been introduced, i.e., the conditioned reverse path (CRP) method and the non-linear identification through feedback of the outputs (NIFO) method. The key idea of these methods is to eliminate the distortions caused by the presence of non-linearities in frequency response functions. In this paper, the theoretical background of the CRP and NIFO methods is briefly recalled. Then, the ability of these techniques to identify the behaviour of an experimental cantilever beam with a local geometrical non-linearity is tested. The results obtained with both methods are compared and discussed. [less ▲]

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