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See detailAnalysis of PCDD/Fs in human blood plasma using CALUX bioassay and GC-HRMS: a comparison
Van Wouwe, Nathalie; Eppe, Gauthier ULiege; Xhrouet, Céline ULiege et al

in Organohalogen Compounds (2003)

Detailed reference viewed: 28 (1 ULiège)
See detailAnalysis of peer interaction among children in a tutoring situation pertaining to mathematical problems of the multiplying type
Crahay, Marcel ULiege; Hindryckx, Geneviève ULiege; Lebe, Martine

in De Corte, E. (Ed.) Powerful learning environments : unravelling basic components and dimensions (2003)

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See detailAnalysis of PEG 400 and 4000 in urine for gut permeability assessment using solid phase extraction and gel permeation chromatography with refractometric detection
Loret, S.; Nollevaux, G.; Remacle, R. et al

in Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences (2004), 805(2), 195-202

We developed a treatment of urine samples allowing the analysis of two intestinal permeability markers: polyethylene glycol (PEG) 400 (highly diffusible; basal permeability indicator) and PEG 4000 (poorly ... [more ▼]

We developed a treatment of urine samples allowing the analysis of two intestinal permeability markers: polyethylene glycol (PEG) 400 (highly diffusible; basal permeability indicator) and PEG 4000 (poorly diffusible; indicator of an abnormal increase of permeability) by a unique gel permeation chromatography (GPC) with refractometric detection. Urinary PEG were extracted using a mixed-bed resin composed of C2 and C 18 layers. Permeability mean values determined in 11 human healthy subjects were 24.20 +/- 9.30% and 0.12 +/- 0.08% for, respectively, PEG 400 and 4000. The percentage of the PEG 4000 permeability value to the one of PEG 400 corresponded to an intestinal permeability index (IPI) of 0.52 +/- 0.35 expressing a low diffusion of this poorly permeability marker. (C) 2004 Published by Elsevier B.V. [less ▲]

Detailed reference viewed: 42 (3 ULiège)
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See detailAnalysis of perforated magnetic shields for electric power applications
Sergeant, Peter; V Sabariego, Ruth ULiege; Crevecoeur, Guillaume et al

in Proceedings of the 13th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2008) (2008)

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See detailAnalysis of perforated magnetic shields for electric power applications
Sergeant, Peter; V Sabariego, Ruth ULiege; Crevecoeur, Guillaume et al

in IET Electric Power Applications (2009), 3(2), 123-132

The shielding performance of perforated magnetic shields for electric power applications is described. The shielding of an axisymmetric induction heating device is studied as a function of frequency ... [more ▼]

The shielding performance of perforated magnetic shields for electric power applications is described. The shielding of an axisymmetric induction heating device is studied as a function of frequency, number of perforations and dimensions of the perforations. From the numerical point of view, the perforations cause the numerical model to be 3D. A numerical optimisation is carried out to find the optimal geometry with respect to the shielding factor and the volume of the shield. For the optimisation, two approaches are presented. The first approach is fast and easy-to-implement, but has limited accuracy. It uses a classical 2D axisymmetric model where the perforations are approximated by ‘axisymmetric air gaps’ resulting in a segmented shield. It is shown how to modify the 2D model to obtain results that are similar to the ones of a 3D model. The second approach is more accurate although quite fast, but more difficult to implement. It combines a 3D thin- shell finite element model with the unmodified 2D model in a space mapping optimisation algorithm. The validation of both models is based on experimental work for an unperforated shield and for the optimised perforated shield. [less ▲]

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See detailAnalysis of performance and robustness of biological switches: local tools for non-local dynamical phenomena.
Trotta, Laura ULiege

Doctoral thesis (2013)

Biological switches are frequently encountered in mathematical modeling of biological systems because binary decisions are at the core of many cellular processes. A bistable switch presents two stable ... [more ▼]

Biological switches are frequently encountered in mathematical modeling of biological systems because binary decisions are at the core of many cellular processes. A bistable switch presents two stable steady-states, each of them corresponding to a distinct decision. These two decisions are assumed to result from the interactions between biochemical effectors at the molecular level. Because these molecular interactions are particularly complex, involving many effectors, mathematical models of biological switches are often high dimensional and nonlinear. Therefore, an analysis of these systems is challenging. In this dissertation, we try to identify principles and tools to study the performance and robustness of biological switches. Our first contribution is to highlight the dynamical nature of these switches. A biological switch encodes a decision-making process rather than a static binary code. It captures dynamical phenomena that are important for the decision-making process, such as decision latencies and reversibility. Our second contribution is methodological. While most of the classical analysis tools are based on a linearization of the system around a stable steady-state, a switch is a non local phenomenon involving a transition between two stable steady-sates. Rather than studying the system around stable equilibria, we identify the local rulers of the decision-making process in both the state and parameter spaces and propose a local analysis in the vicinity of these particular points. Our third contribution is to emphasize the added value of an abstract (that is, mathematical) framework for the analysis of biological switches. By studying different models, we point out that the same principles can be used to encode dynamical phenomena in very different cellular processes. Physiological processes as different as apoptosis, the cellular choice of death, and action potential, the cellular choice to emit an electrical spike, share common features when regarded as decision-making processes. [less ▲]

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See detailAnalysis of periods with strong and coherent CO2 advection over a forested hill
Zeri, Marcelo; Rebmann, Corinna; Feigenwinter, Christian et al

in Agricultural and Forest Meteorology (2010), 150(5), 674-683

Horizontal and vertical advective fluxes of CO2 measured during the CarboEurope-IP advection experiment (ADVEX) at the Wetzstein spruce forest site in Thuringia, Germany, were related to wind direction ... [more ▼]

Horizontal and vertical advective fluxes of CO2 measured during the CarboEurope-IP advection experiment (ADVEX) at the Wetzstein spruce forest site in Thuringia, Germany, were related to wind direction, stratification regime and friction velocity u*. Measurements of wind speed and direction carried out at one of the slopes of the ridge revealed the existence of reverse flow below the canopy on the downwind side. This uphill flowoccurred concurrently with the advective fluxes measured at the top of the hill. Such result is in agreement with recent modeling works that support the existence of advection at low hills covered with a canopy. Another experimental evidence that suggest a link between advection at this site with the flow over the hill came from the analysis of the horizontal gradient of CO2 inside the volume formed by the ADVEX towers. It was observed that CO2 accumulated near the downwind side of the crest for cross-ridge flows, what is consistent with another modeling work of the transport of scalars across a low hill covered with a canopy. [less ▲]

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See detailAnalysis of physical activity at work of university employees by accelerometry
Dubru, Gilles ULiege; Mottard, Julien; Cloes, Marc ULiege

Poster (2019, June)

Background and purpose It is commonly accepted that physical activity (PA) improves health and well-being. At work, the PA benefits go not only to the employees but also to the employers (Ecorys, 2017 ... [more ▼]

Background and purpose It is commonly accepted that physical activity (PA) improves health and well-being. At work, the PA benefits go not only to the employees but also to the employers (Ecorys, 2017). Although researchers are fond of physical activity data, the literature appears to be relatively poor in terms of PA rates for university staff, even if it is their own professional context. In the perspective of changing the habits of the employees of the University of Liège (ULiège), we analyzed the profile of their activity/physical inactivity by means of a questionnaire (Dubru et al., 2018). The purposes of the present study consisted to supplement the previous data using accelerometry and to prepare recommendations for the authorities of the institution. Methods Accelerometers Actigraph GT3X+ were distributed to 47 subjects working at the ULiège selected through a stratified sampling respecting the gender, age, and location of the workplace. Accelerometers were worn on the right hip for 7 days, day and night as recommended by the literature (Migueles et al., 2017). Troiano et al. (2007)’s epochs and cut-points were chosen. Results Subjects walked an average of 8,069 (± 6463) steps/day, with no difference by gender. According the age, a significant difference appeared between <39 and 59> categories. Based on the Tuder-Lock and Basset classification system (2004), only 11 participants can be considered physically active (23%).p <.05). Per week, employees spent 1918 min (±564) in low PA, 223 min (±165) in moderate PA, and 23 min (±56) in vigorous PA. The data confirm the poor PA level identified previously by questionnaires. Conclusion and implications Despite a large disparity in the individual results, it would be urgent to implement an institutional policy promoting physical activity at the ULiège. Such project would be an interesting challenge for the PE department. Practical recommendations are proposed. [less ▲]

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See detailAnalysis of PIV measurements using modal decomposition techniques, POD and DMD, to study flow structures and their dynamics within a stirred-tank reactor
de Lamotte, Anne ULiege; Delafosse, Angélique ULiege; Calvo, Sébastien ULiege et al

in Chemical Engineering Science (2018)

The present work is a comparative analysis of Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) computed on experimental turbulent velocity fields measured in a 20L-tank stirred ... [more ▼]

The present work is a comparative analysis of Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) computed on experimental turbulent velocity fields measured in a 20L-tank stirred by two Rushton impellers at two rotating speeds, N = 150 and 300 rpm. POD identifies flow structures that optimally capture the total kinetic energy of the flow, while DMD identifies structures that significantly contribute to the dynamics of the flow. The experimental data, i.e. the instantaneous radial and axial velocity fields, come from 2-D Particle Image Velocimetry (PIV). The flow motion is turbulent, and it occurs over a wide range of length and time scales, from equipment-dependent large-scale coherent structures to the smallest-scale eddies where energy dissipation takes place. It thus provides an interesting benchmark case for the comparison between POD and DMD, which are based on energy and dynamic analysis, respectively. POD analysis reveals that the most energetic structures are related to the inherent periodic unsteadiness due to the relative motion between the rotating impeller blades and the non-moving baffles. Apart from the mean field, the first most energetic group of modes is related to trailing vortices induced by the Rushton turbines and is associated to a frequency equivalent to the blade passage frequency and its overtones. The second most energetic group of modes is related to vortical structures in the impeller stream and is associated to a frequency equivalent to the rotating speed. DMD analysis identifies flow structures that are found similar to these most energetic modes, although differences appear due to the fact that DMD isolates structures associated to a single frequency and their corresponding growth/decay rate. As in POD, the relative importance of each DMD mode can be estimated using an appropriately defined energy criterion. Comparison of the results from both modal decomposition methods points out their complementarity and their potential for describing the spatial and time characteristics of the flow within a stirred tank. [less ▲]

Detailed reference viewed: 123 (24 ULiège)
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See detailAnalysis of plasma IGF-I hormone levels in Holstein-Friesian Heifers
Horvai-Szabo, M.; Renaville, Robert ULiege; Dohy, J.

in Journal of Dairy Science (2000), 83(suppl 1), 48

Detailed reference viewed: 6 (0 ULiège)
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See detailAnalysis of plasma IGF-I hormone levels in Holstein-Friesian Heifers.
HorvaI-Szabo, M.; Renaville, Robert ULiege; Dohy, J.

Poster (2000)

Detailed reference viewed: 9 (0 ULiège)
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See detailAnalysis of polar lipids from milk fat globale membrane (MFGM) by SPE and HPLC-ELSD.
Bodson, Pascal; Danthine, Sabine ULiege; Blecker, Christophe ULiege

Poster (2006, October)

Detailed reference viewed: 41 (1 ULiège)
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See detailAnalysis of Pollen and Nectar of Arbutus unedo as a Food Source for Bombus terrestris (Hymenoptera : Apidae)
Rasmont, Pierre; Regali, Ariane; Ings, Thomas C. et al

in Journal of Economic Entomology (2005), 98(3), 656-663

Detailed reference viewed: 103 (1 ULiège)
See detailAnalysis of pollutants with GcxGc-HRTOFMS
Focant, Jean-François ULiege

Scientific conference (2011, February)

Detailed reference viewed: 44 (0 ULiège)
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See detailAnalysis of polychlorinated biphenyl residues in human plasma by gas chromatography-mass spectrometry
Charlier, Corinne ULiege; Dubois, Nathalie ULiege; CUCCHIARO, Séverine ULiege et al

in Journal of Analytical Toxicology (2003), 27(2), 74-77

A method for the determination of seven polychlorinated biphenyl residues in plasma by gas chromatography-mass spectrometry was developed. The analytes were isolated from human plasma by liquid-liquid ... [more ▼]

A method for the determination of seven polychlorinated biphenyl residues in plasma by gas chromatography-mass spectrometry was developed. The analytes were isolated from human plasma by liquid-liquid extraction, followed by solid-phase extraction, and separation on an HP5 Trace column. Ionization mode was electronic impact, and selected ion storage was used for isolation and quantitation of the compounds. The method was evaluated for its analytical performances and therefore applied to monitor the prevalence of these seven polychlorinated biphenyl residues in a female population. Eighty samples were analyzed, and 82.5% presented detectable amounts of at least one residue. For the population study, results were reported on a lipid-adjusted basis. Because the proposed method is satisfying and seems to be suitable for the quantitation of PCB congeners in a general population, epidemiological studies to evaluate the widespread contamination with these environmental compounds can be proposed. [less ▲]

Detailed reference viewed: 54 (12 ULiège)
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See detailAnalysis of POPs in 20μL blood by MEPS-GC-MS/MS
L'Homme, Benjamin ULiege; Focant, Jean-François ULiege

in Hyphenated Techniques in Chromatography HTC-13 - Book of abstracts (2014, January)

Detailed reference viewed: 49 (2 ULiège)
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See detailAnalysis of positional candidate genes in the AAA1 susceptibility locus for abdominal aortic aneurysms on chromosome 19.
Lillvis, J. H.; Kyo, Y.; Tromp, G. et al

in BMC Medical Genetics (2011), 12(1), 14

ABSTRACT: BACKGROUND: Abdominal aortic aneurysm (AAA) is a complex disorder with multiple genetic risk factors. Using affected relative pair linkage analysis, we previously identified an AAA ... [more ▼]

ABSTRACT: BACKGROUND: Abdominal aortic aneurysm (AAA) is a complex disorder with multiple genetic risk factors. Using affected relative pair linkage analysis, we previously identified an AAA susceptibility locus on chromosome 19q13. This locus has been designated as the AAA1 susceptibility locus in the Online Mendelian Inheritance in Man (OMIM) database. METHODS: Nine candidate genes were selected from the AAA1 locus based on their function, as well as mRNA expression levels in the aorta. A sample of 394 cases and 419 controls was genotyped for 41 SNPs located in or around the selected nine candidate genes using the Illumina GoldenGate platform. Single marker and haplotype analyses were performed. Three genes (CEBPG, PEPD and CD22) were selected for DNA sequencing based on the association study results, and exonic regions were analyzed. Immunohistochemical staining of aortic tissue sections from AAA and control individuals was carried out for the CD22 and PEPD proteins with specific antibodies. RESULTS: Several SNPs were nominally associated with AAA (p < 0.05). The SNPs with most significant p-values were located near the CCAAT enhancer binding protein (CEBPG), peptidase D (PEPD), and CD22. Haplotype analysis found a nominally associated 5-SNP haplotype in the CEBPG/PEPD locus, as well as a nominally associated 2-SNP haplotype in the CD22 locus. DNA sequencing of the coding regions revealed no variation in CEBPG. Seven sequence variants were identified in PEPD, including three not present in the NCBI SNP (dbSNP) database. Sequencing of all 14 exons of CD22 identified 20 sequence variants, five of which were in the coding region and six were in the 3'-untranslated region. Five variants were not present in dbSNP. Immunohistochemical staining for CD22 revealed protein expression in lymphocytes present in the aneurysmal aortic wall only and no detectable expression in control aorta. PEPD protein was expressed in fibroblasts and myofibroblasts in the media-adventitia border in both aneurysmal and non-aneurysmal tissue samples. CONCLUSIONS: Association testing of the functional positional candidate genes on the AAA1 locus on chromosome 19q13 demonstrated nominal association in three genes. PEPD and CD22 were considered the most promising candidate genes for altering AAA risk, based on gene function, association evidence, gene expression, and protein expression. [less ▲]

Detailed reference viewed: 40 (3 ULiège)