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See detailEvaluation of Non-negative matrix Factorization of grey matter in age prediction
Varikuti, Deepthi; Genon, Sarah ULiege; Sotiras, Aristeidis et al

Poster (2017, June)

Introduction: It has been shown that machine-learning methods applied to voxel-based morphometry (VBM) data allows the prediction of brain age [1]. Dimensionality reduction is a critical aspect of such ... [more ▼]

Introduction: It has been shown that machine-learning methods applied to voxel-based morphometry (VBM) data allows the prediction of brain age [1]. Dimensionality reduction is a critical aspect of such brain-based prediction of phenotypical characteristics to counter the curse of dimensionality associated with voxel-wise analysis. While previous age-predictions have employed PCA based compression, non-negative matrix factorization (NNMF) has recently been suggested as a plausible factorization of high-dimensional VBM data [4]. Non-negativity and sparsity of the components obtained from NNMF facilitate relatively more optimal solution than the PCA based compression [4]. Here, we evaluate, i) whether NNMF compression allows predictions of biological age that reproduce those from previously reported analyses [2], ii) the impact of the NNMF’s granularity on the prediction accuracy, iii) the possible effect of the factorizations derived from different datasets on the prediction, and iv) whether explicit adjustment can address the model bias inherent to many brain-based predictions. Methods: VBM8 preprocessing (using only non-linear modulation and 8 mm FWHM smoothing [3]) was used to compute voxel-wise GM volumes for two datasets, 1) 693 healthy older adults (age: 55-75 years) scanned at a single site (“1000BRAINS) [1], 2) 1084 healthy adults (age: 18-81 years), scanned at multiple sites (“Mixed”) (Fig 1A). NNMF solutions for both groups were derived at different levels of granularity. Age prediction was performed by fitting LASSO regression models either on the coefficient matrix from the respective NNMF or by those that were derived from projecting a group’s data on the respective other groups components. Model generalization was evaluated by 10-fold cross-validation replicated 25 times. To address the known bias towards the mean, i.e., overestimation of young and underestimation of older subjects, we additionally tested models that explicitly fitted the regression-slope between the real and predicted training set and used this to adjust the expected slope of the test set to 45 degrees. Results: In both datasets, NNMF components resembled neurobiologically reasonable patterning of the brain (Fig 1B). Prediction accuracy based on the projection of data on the components from either group was virtually identical (Fig 2A). For both datasets, mean absolute errors (MAE) declined with higher granularity of the components and reached values well comparable to previous approaches even when using components derived from an independent sample (MAE: 3.6 years for 1000BRAINS; 6.4 years for Mixed). Plotting the prediction error relative to the biological age of the subjects revealed the bias towards the mean across both datasets (Fig 2B). Adjusting for the slope estimated in the training set allows removing this bias, though it needs to be noted that this comes at the cost of reduced precision, i.e., unbiased estimates yield a slightly higher MAE. Conclusion: NNMF allows the definition of co-variation patterns in VBM data. Due to the non- negativity and sparseness, NNMF enable substantially easier and higher biological interpretation than other methods for data compression such as PCA [4]. We showed that NNMF compression of VBM data over the lifespan allows predicting previously unseen subjects’ age with a precision that is comparable to earlier reports using PCA for data compression [2], while offering the potential for neurobiological interpretation. Importantly, accuracy seems to be independent of whether the components were derived from the same dataset or from a dataset that is not only independent but also different in age distribution. We note that accuracies tend to continuously decrease with higher granularity, although performance tends to plateau at about 300 components. Finally, adjusting the inherent bias of sparse regression models yields unbiased out-of-sample predictions but comes at the expense of slightly higher mean errors. [less ▲]

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See detailEVALUATION OF NOVEL SYNTHETIC POLYCATION ACTION ON VISCOELASTIC PROPERTIES OF ERYTHROCYTE MEMBRANE
Riquelme, B; Foresto, P; Relancio, F et al

in Annales AFA (2006)

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See detailEvaluation of observer effect in botanical surveys of grasslands
Couvreur, Jean-Marc; Fievet, Vincent; Smits, Quentin et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2015)

Description of the subject. A field study has been conducted on 24 grasslands with five different botanical experts in order to assess inter-observer bias when making botanical surveys as well as the ... [more ▼]

Description of the subject. A field study has been conducted on 24 grasslands with five different botanical experts in order to assess inter-observer bias when making botanical surveys as well as the possible consequences in terms of descripting a semi-natural habitat. Objectives. Fieldwork has been conducted to understand the most important factors of variability affecting botanical surveys conducted by several observers. These results were used to suggest practical solutions to enhance the quality of such surveys. Method. Five observers performed a complete botanical survey of 24 grassland plots in the Famenne (Wallonia, Belgium) in June 2009. All surveys were statistically analyzed in order to detect and quantify the sources of variability between observers. The main parameters compared are the habitat diagnosis made on the field by the experts, the rate of detection of the characteristic species as well as their coverage in each plot. Results. Regarding habitat identification, the biggest differences between observers are seen in plots where the composition is intermediate between a habitat in good and in bad status. Overall, there was a slight tendency to undervalue the quality of the habitat. The analysis revealed that the primary cause of variability between observers is the fact that the experts did not always strictly follow the criteria for habitat identification. As regards the comparison between observers, several sources of variability were identified. The main ones are the variability of the estimated coverage of some plants, the variability of the detection rate of characteristic species, as well as the variability of the prospecting effort that can be sub-optimal in each plot. Conclusions. Some of the sources of variability that have been pointed out can be resolved easily, other have to be taken in consideration when comparing the results of surveys in the future. The solutions proposed to reduce the variability between observers are to encourage better self-control of the parameters to be taken into account at each step of the work, the organization of targeted training courses and more standardized prospecting efforts. Keywords. Grassland, detection rate, cover rate, observer effect, bias, prospection, monitoring, habitat, identification. [less ▲]

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See detailEvaluation of ocean carbon cycle models with data-based metrics
Matsumoto, K.; Sarmiento, J. L.; Key, R. M. et al

in Geophysical Research Letters (2004), 31(7),

New radiocarbon and chlorofluorocarbon-11 data from the World Ocean Circulation Experiment are used to assess a suite of 19 ocean carbon cycle models. We use the distributions and inventories of these ... [more ▼]

New radiocarbon and chlorofluorocarbon-11 data from the World Ocean Circulation Experiment are used to assess a suite of 19 ocean carbon cycle models. We use the distributions and inventories of these tracers as quantitative metrics of model skill and find that only about a quarter of the suite is consistent with the new data-based metrics. This should serve as a warning bell to the larger community that not all is well with current generation of ocean carbon cycle models. At the same time, this highlights the danger in simply using the available models to represent the state-of-the-art modeling without considering the credibility of each model. [less ▲]

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See detailEvaluation of ocean model ventilation with CFC-11: comparison of 13 global ocean models
Dutay, J.-C.; Bullister, J. L.; Doney, S. C. et al

in Ocean Modelling (2002), 4(2), 89-120

We compared the 13 models participating in the Ocean Carbon Model Intercomparison Project (OCMIP) with regards to their skill in matching observed distributions of CFC-11. This analysis characterizes the ... [more ▼]

We compared the 13 models participating in the Ocean Carbon Model Intercomparison Project (OCMIP) with regards to their skill in matching observed distributions of CFC-11. This analysis characterizes the abilities of these models to ventilate the ocean on timescales relevant for anthropogenic CO2 uptake. We found a large range in the modeled global inventory (+/- 30\%), mainly due to differences in ventilation from the high latitudes. In the Southern Ocean, models differ particularly in the longitudinal distribution of the CFC uptake in the intermediate water, whereas the latitudinal distribution is mainly controlled by the subgrid-scale parameterization. Models with isopycnal diffusion and eddy-induced velocity parameterization produce more realistic intermediate water ventilation. Deep and bottom water ventilation also varies substantially between the models. Models coupled to a sea-ice model systematically provide more realistic AABW formation source region; however these same models also largely overestimate AABW ventilation if no specific parameterization of brine rejection during sea-ice formation is included. In the North Pacific Ocean, all models exhibit a systematic large underestimation of the CFC uptake in the thermocline of the subtropical gyre, while no systematic difference toward the observations is found in the subpolar gyre. In the North Atlantic Ocean, the CFC uptake is globally underestimated in subsurface. In the deep ocean, all but the adjoint model, failed to produce the two recently ventilated branches observed in the North Atlantic Deep Water (NADW). Furthermore, simulated transport in the Deep Western Boundary Current (DWBC) is too sluggish in all but the isopycnal model, where it is too rapid. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailEvaluation of OCMIP-2 ocean models' deep circulation with mantle helium-3
Dutay, J. C.; Jean-Baptiste, P.; Campin, J. M. et al

in Journal of Marine Systems (2004), 48(1-4), 15-36

We compare simulations of the injection of mantle helium-3 into the deep ocean from six global coarse resolution models which participated in the Ocean Carbon Model Intercomparison Project (OCMIP). We ... [more ▼]

We compare simulations of the injection of mantle helium-3 into the deep ocean from six global coarse resolution models which participated in the Ocean Carbon Model Intercomparison Project (OCMIP). We also discuss the results of a study carried out with one of the models, which examines the effect of the subgrid-scale mixing parameterization. These sensitivity tests provide useful information to interpret the differences among the OCMIP models and between model simulations and the data. We find that the OCMIP models, which parameterize subgrid-scale mixing using an eddy-induced velocity, tend to underestimate the ventilation of the deep ocean, based on diagnostics with delta(3)He. In these models, this parameterization is implemented with a constant thickness diffusivity coefficient. In future simulations, we recommend using such a parameterization with spatially and temporally varying coefficients in order to moderate its effect on stratification. The performance of the models with regard to the formation of AABW confirms the conclusion from a previous evaluation with CFC-11. Models coupled with a sea-ice model produce a substantial bottom water formation in the Southern Ocean that tends to overestimate AABW ventilation, while models that are not coupled with a sea-ice model systematically underestimate the formation of AABW We also analyze specific features of the deep He-3 distribution (He-3 plumes) that are particularly well depicted in the data and which put severe constraints on the deep circulation. We show that all the models fail to reproduce a correct propagation of these plumes in the deep ocean. The resolution of the models may be too coarse to reproduce the strong and narrow currents in the deep ocean., and the models do not incorporate the geothermal heating that may also contribute to the generation of these currents. We also use the context of OCMIP-2 to explore the potential of mantle helium-3 as a tool to compare and evaluate modeled deep-ocean circulations. Although the source function of mantle helium is known with a rather large uncertainty, we find that the parameterization used for the injection of mantle helium-3 is sufficient to generate realistic results, even in the Atlantic Ocean where a previous pioneering study [J. Geophys. Res. 100 (1995) 3829] claimed this parameterization generates inadequate results. These results are supported by a multi-tracer evaluation performed by considering the simulated distributions of both helium-3 and natural C-14, and comparing the simulated tracer fields with available data. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailEvaluation of odour impact from a landfill area and a waste treatment facility through the application of two atmospheric dispersion models.
Ubeda, Yolanda; Ferrer, M.; Sanchis, E. et al

Conference (2010, July)

Odour emission from landfill areas has a high potential to cause significant annoyance to people living in their surroundings. In order to avoid odour nuisance, it is crucial to select the best location ... [more ▼]

Odour emission from landfill areas has a high potential to cause significant annoyance to people living in their surroundings. In order to avoid odour nuisance, it is crucial to select the best location in the project phase of these facilities. In the present work, two different atmospheric dispersion models were employed to predict odour impact from a projected landfill area and a waste treatment facility. The first model used was a simplified Gaussian Atmospheric Dispersion model developed by the authors. Calculated odour concentrations were represented using GIS tools (Esri ®ArcMapTM software). Regarding to the second model, it was a commercial bi-Gaussian Atmospheric Dispersion one. The odour impact of the waste treatment facility is expected to be low, because of the high efficiency of air biofiltration treatments and the dispersion effect of the stack. The shape and the reach of odour percentile contours were quite similar, providing coherent results between two models. Concerning the landfill installation, odour concentrations were modelled for the prevailing winds. The results obtained with both models differ in the reach of odour. The maximum distance obtained by the simple dispersion model was 1.5 km, compared with the almost 5 km modelled by the commercial bi-Gaussian one. The reasons of this disparity could be caused by the difference in the dispersion coefficients employed in the two models and also an error related to ground level emission. In addition, the meteorological conditions in the Mediterranean typically present a high proportion of calm winds, which provided worse dispersion results and did not reflect the real odour dispersion. Odour emission rate seems to be overestimated, and this could explain the high distance reached by odour. Field measurements are required when landfill installation becomes operational, in order to determine the real impact of odour. Bi-Gaussian Dispersion Models may not be appropriate to quantify the odour impact from agricultural sources. [less ▲]

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See detailEvaluation of oral corticosteroids and phosphodiesterase-4 inhibitor on the acute inflammation induced by inhaled lipopolysaccharide in human.
Michel, Olivier; Dentener, Mieke; Cataldo, Didier ULiege et al

in Pulmonary Pharmacology & Therapeutics (2007), 20(6), 676-83

Background Endotoxins are pro-inflammatory substances present in the environment. In man, inhalation of its purified derivative lipopolysaccharide (LPS) induces inflammation related to macrophages and ... [more ▼]

Background Endotoxins are pro-inflammatory substances present in the environment. In man, inhalation of its purified derivative lipopolysaccharide (LPS) induces inflammation related to macrophages and neutrophils. Corticosteroids and phosphodiesterase (PDE)-4 inhibitors have inhibiting effects on macrophages and neutrophils, respectively. This study investigated the effect of prednisolone and of the PDE-4 inhibitor cilomilast on the LPS-induced acute inflammation. Methods The study was a placebo-controlled, double-blind crossover design. On three occasions, at 2 weeks interval, 16 healthy subjects inhaled 50 μg LPS after a 6-day treatment with cilomilast (15 mg bd), prednisolone (10 mg bd) or placebo. For the assessment of the inflammatory response, induced sputum was obtained before inclusion and 6 h post-LPS while blood samples were collected before, 6 and 24 h post-LPS. Results Inhaled LPS induced an increase in sputum neutrophils (p<0.0001), logMMP-9 (p<0.05), logMMP-9/TIMP-1 (p<0.01) and logTNF-α (p<0.02). At the blood level there were significant rise in neutrophilia (p<0.001), E-selectin (p<0.02), C-reactive protein (CRP) (p<0.001) and LPS-binding protein (p<0.001). There was both a slight, but not significant, increase in body temperature and decrease in forced expiratory volume in 1 s (FEV1). Neither prednisolone nor cilomilast had protective effect on the LPS-induced airways’ inflammation. The LPS-induced CRP acute-phase protein of inflammation (0.58±0.13 and 3.52±0.41 mg/dL, before and after LPS, respectively) was significantly inhibited by a pre-treatment with prednisolone (1.39±0.32 mg/dL, p<0.01) and attenuated (2.65±0.30 mg/dL, p=0.09) with cilomilast. Conclusion In healthy subjects, while the LPS-induced airways’ inflammation was not modified either by oral prednisolone or by PDE-4 inhibitor cilomilast (at actual dosage), the LPS-induced acute phase of blood inflammation was reduced by prednisolone. [less ▲]

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See detailEvaluation of organic dust components cytotoxicity on thp1 monocytes-derived-macrophages using high content analysis
Ramery, Eve ULiege; O'Brien, Peter James

in Veterinary Clinical Pathology (2011, December), 40(4), 583

Background: Organic dust contains pathogen associated molecular patterns (PAMPs) which can induce, following chronic exposure, significant airway diseases. Mononuclear phagocytes are key protecting cells ... [more ▼]

Background: Organic dust contains pathogen associated molecular patterns (PAMPs) which can induce, following chronic exposure, significant airway diseases. Mononuclear phagocytes are key protecting cells of the respiratory tract. Several studies have investigated the effects of PAMPs, and mainly endotoxins, on cytokine production. However the sub-lethal cytotoxicity of organic dust components on macrophages has not been tested yet. The novel technology of high content analysis (HCA) is already used to assess subclinical drug-induced toxicity. It combines the capabilities of flow cytometry, intracellular fluorescence probes, and image analysis and enables to perform rapid multiple analysis in large numbers of samples. Objectives: The purpose of the present study was, by using HCA, to investigate the cytotoxicity of the 3 major PAMPs contained in organic dust, ie. endotoxin (LPS), peptidoglycan (PGN) and β-glucans (zymosan) on THP-1 monocyte-derived macrophages. Methods: LPS was used at concentrations of 0.005, 0.01, 0.02, 0.05, 0.1 and 1 μg/ml; PGN and zymosan were used at concentrations of 1, 5, 10, 50, 100 and 500 μg/ml. Cells were exposed to PAMPs for 24 hours. In addition, the oxidative burst and the phagocytic capabilities of the cells were tested. Results: An overlap between PGN intrinsic fluorescence and red/far-red fluorescent dyes occurred, rendering the evaluation of some parameters impossible for PGN. LPS induced sub-lethal cytotoxicity at the lowest dose (from 10 ng/ml). However, the most spectacular changes occurred with zymosan. In addition, zymosan, but not LPS, induced phagosome maturation and oxidative burst. Conclusions: Given the fact that β-glucans can be up to 100 fold more concentrated in organic dust than LPS, these results suggest that β-glucans could play a major role in macrophages impairment following heavy dust exposure and will deserve further investigation in the near future. [less ▲]

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See detailEvaluation of original dual thromboxane A2 modulators as anti-angiogenic agents
Dassesse, Thibaut; de Leval, Xavier; Dogné, Jean-Michel et al

Scientific conference (2006)

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See detailEvaluation of original dual thromboxane A2 modulators as antiangiogenic agents
de Leval, Xavier; Dassesse, Thibaut; Dogné, Jean-Michel ULiege et al

in Journal of Pharmacology and Experimental Therapeutics (The) (2006), 318(3), 1057-1067

Angiogenesis is a promising target for the therapy of several diseases including cancer. This study was undertaken to characterize the antiangiogenic properties of a series of original dual thromboxane A ... [more ▼]

Angiogenesis is a promising target for the therapy of several diseases including cancer. This study was undertaken to characterize the antiangiogenic properties of a series of original dual thromboxane A(2) (TXA(2)) inhibitors derived from torasemide, a marketed loop diuretic with TXA(2) antagonistic properties, by evaluating their effects on human endothelial cell migration, adhesion, and viability in vitro, as well as in the ex vivo rat aortic ring assay. All drugs tested exhibited a marked affinity toward human platelet TXA(2) receptor, significantly prevented platelet aggregation induced by U-46,619, a stable TXA(2) receptor agonist, and inhibited platelet TXA(2) synthase without affecting cyclooxygenase (COX)-1 or COX-2 enzymatic activities. These dual TXA(2) inhibitors dose dependently inhibited endothelial cell migration in chemotaxis assays using vascular endothelial growth factor ( VEGF) as a chemoattractant but failed to affect cell adhesion and viability. The highest rates of cell migration inhibition were obtained with original compounds BM-567 and BM-573 (50.3 and 59.4% inhibition, respectively) when used at the final concentration of 10 mu M. In addition, pretreatment of endothelial cells with these two drugs significantly prevented U-46,619-induced intracellular Ca2+ pool mobilization, thus suggesting a mechanistic link between inhibition of the TXA(2) pathway and reduced endothelial cell migration. Treatment of rat aortic explants with U-46,619 (9,11- dideoxy- 9,11- methanoepoxyprostaglandin F 2) significantly enhanced vessel sprouting whereas aortic rings treated with some of the compounds, including BM-567 (N-n-pentyl-N'-[2-(cyclohexylamino)-5-nitrobenzenesulfonyl] urea) and BM-573 (N-tert-butyl-N'-[5-nitro-2p- toluylaminobenzenesulfonyl]urea), showed a significant decrease in vessel sprouting, which was not reversed by the addition of VEGF. These data suggest that our original dual TXA(2) inhibitors bear antiangiogenic properties, mainly by inhibiting endothelial cell migration. [less ▲]

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See detailEvaluation of oscillometric devices for detection of hypotension in anaesthetized dogs.
Gommeren, Kris ULiege; Peyron, Clémence ULiege; Lacoste-Garanger, Nicolas ULiege et al

in Proceedings of the 9th EVECCS Annual meeting (2010)

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See detailEvaluation of oxygen consumption during field exercise tests in Standardbred trotters
Van Erck, Emmanuelle; Votion, Dominique ULiege; Serteyn, Didier ULiege et al

in Equine & Comparative Exercise Physiology (2007), 4(1), 43-49

Reasons for performing the study: In human exercise physiology, the current gold standard for evaluating aerobic capacity is the measurement of oxygen consumption (VO2max) and maximal oxygen uptake ... [more ▼]

Reasons for performing the study: In human exercise physiology, the current gold standard for evaluating aerobic capacity is the measurement of oxygen consumption (VO2max) and maximal oxygen uptake (VO2max). The evaluation of VO2, in horses is performed in some laboratories equipped with a treadmill but has only been exceptionally reported in field conditions because of the lack of adapted equipment. Objectives: The aim of this study was (1) to assess the feasibility of VO2 measurement on the track using a recently validated portable breath-by-breath gas analyser system adapted to horses (Cosmed K4b® and Equimask®), (2) to compare these results with those obtained during a treadmill exercise test and (3) to study correlations between VO2 and physiological parameters usually measured in field condition such as heart rate (HR), lactataemia (LA) and the speed at which HR equals 200 beats per minute (bpm) (V200) or LA 4 mmol-1 (VLA4). Methods: Five healthy Standardbred trotters in training were submitted to two stepwise incremental exercise tests, one driven on the racetrack and the other on a high-speed treadmill with a 4% incline. Speed (v), HR, ventilatory parameters and VO2 were continu¬ously recorded throughout the duration of the tests and LA was evaluated after each step. Results: All horses com¬pleted the test satisfactorily after an initial acclimatization to the mask. There were marked individual differences in ventilatory strategy, and breathing frequency (Rf) at the higher levels of exercise was noticeably low. The VCO2 measurements were incoherent. There were no significant differences between track and treadmill maximal data obtained during the last stop [VO2peak (track: 139.9 ± 8.9 ml kg-1min-1; treadmill: 139.9 ± 13.4 ml kg-1min-1), LAmax (track: 6.5 ± 1.6mmol-1; treadmill: 7.3 ± 3.Ommol-1-1), HRma (track: 229 ± 6.2 bpm; treadmill:222 ± 13 bpm)], although the maximal speed required to reach similar workloads was significantly higher on the track (11.9 ± 0.6 ms-1 vs. 9.7 ± 0.4 ms-1). The correlation between VO, and HR (r= 0.87; P < 0.001) and VO2 and LA (r = 0.75; P < 0,001) during both tests was good but no correlation was found between VO2peak and HRmax, LAmax, V200 or VLA4. Conclusions: This is the first report of a practical portable system to measure VO2 and ventilation continuously during high-speed field exercise tests. However, current mask design markedly influences ventilation and could have prohibited the attainment of VO2max Furthermore, consistent VCO2 measurements should be implemented by the manufacturers. Potential relevance: Continuous breath-by-breath ventilation and VO2 measurements can be recorded in horses in the field at submaximal levels. With necessary adaptations to the system entailed, this study opens new perspectives in the analysis of physiological and metabolic mechanisms of exercise in the equine species in genuine track conditions. [less ▲]

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See detailEvaluation of p-[F-18]MPPF, 5-HT1A antagonist, in rats: tissue distribution, autoradiography and metabolism.
Plenevaux, Alain ULiege; Aerts, Joël ULiege; Lemaire, Christian ULiege et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1997), 38

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See detailEvaluation of pairwise calibration techniques for range cameras and their ability to detect a misalignment
Lejeune, Antoine ULiege; Grogna, David ULiege; Van Droogenbroeck, Marc ULiege et al

in International Conference on 3D Imaging (IC3D) (2014, December)

Many applications require the use of multiple cameras to cover a larger volume. In this paper, we evaluate several pair-wise calibration techniques dedicated to range cameras. We compare the precision of ... [more ▼]

Many applications require the use of multiple cameras to cover a larger volume. In this paper, we evaluate several pair-wise calibration techniques dedicated to range cameras. We compare the precision of a self-calibration technique based on the movement in front of the cameras to object based calibration. While the self-calibration method is less precise than its counterparts, it yields a first estimation of the transformation between the cameras and permits to detect when the cameras become mis-aligned. Therefore it is useful in a practical situations. [less ▲]

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See detailEvaluation of particle translocation across the alveolo-capillary barrier in isolated perfused rabbit lung model
Nemmar, A.; Hamoir, J.; Nemery, B. et al

in Toxicology (2005), 208(1), 105-113

Particulate air pollution is associated with respiratory and cardiovascular morbidity and mortality. It has been suggested that ultrafine particles are able to translocate from the airways into the ... [more ▼]

Particulate air pollution is associated with respiratory and cardiovascular morbidity and mortality. It has been suggested that ultrafine particles are able to translocate from the airways into the bloodstream in vivo. We have investigated this in an isolated perfused and ventilated rabbit lung preparation lacking pulmonary lymphatic flow. Fluorescent polystyrene particles of different diameters (24, 110 or 190 nm) and surface chemistry (carboxylate or amine modified) were injected either intratracheally (i.t.) or intravascularly (i.v.) and, after a period of 2 h, their presence in the perfusion liquid or in the bronchoalveolar lavage (BAL) fluid, was assessed by spectrofluorimetry. Vascular pressures and lung weights were monitored. Following the i.t. administration, no particle translocation was observed from the alveoli into the vascular compartment. Similarly, no particle translocation was found after i.v. administration of particles. However, when microvascular permeability was pharmacologically increased by administering histamine (10(-4) M) in the vascular compartment, inducing a positive driving force provided by fluid filtration, a fluorescent signal in BAL was recorded (2.5 +/- 1% of the dose of particles administered), suggesting a translocation of particles through the alveolo-capillary barrier. We conclude that ultrafine polystyrene particles cannot significantly diffuse from lung into the vascular compartment in our model, but they are able to translocate in the opposite direction when the microvascular permeability is increased by histamine. The relevance of these ex vivo findings for the in vivo translocation of inhaled ultrafine particles remains to be established [less ▲]

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See detailEVALUATION OF PERFORMANCES OF HYBRID ELECTRIC ENERGY STORAGE SYSTEM (LI-ION BATTERIES/ SUPERCAPACITORS) EV AND HEV APPLICATIONS
Lemaire, Julien ULiege; Nzisabira, Jonathan ULiege; Duysinx, Pierre ULiege

Conference (2013, June)

Electric and hybrid electric vehicles sound the best alternative to internal combustion engines. However, energy storage systems must have a sufficient power and energy density (to answer accelerations ... [more ▼]

Electric and hybrid electric vehicles sound the best alternative to internal combustion engines. However, energy storage systems must have a sufficient power and energy density (to answer accelerations, regenerate breaking power and have sufficient autonomy). The advantage of batteries is their relatively large energy capacity. But batteries life time and capacity are limited by the number and the magnitude of current peaks [1]. The efficiency also depends on the discharge current regime. More there is high peak current, more the efficiency decreases [2]. Electrical double layer capacitors (EDLC) have a huge specific power and long life cycle because of their internal working principles especially based on charges transfer [3]. The main disadvantage is low specific energy. A combination of the two systems is interesting to gain energy capacity and lengthens the life of the batteries by limiting current peaks inside. The aim of this study is to evaluate the performances of a hybrid energy storage system (Li-ion batteries and EDLC) using a simulation tool. Batteries and EDLC are assembled in parallel in a high power bus. Batteries are directly linked on the bus because their nearly constant voltage. Conversely EDLC have to be connected with a DC/DC converter. Efficiencies of the elements are dependent on the actual current within each component. Given a total energy capacity and a current profile, the difference in final energy capacity may vary from about 15% whether the storage system is composed of batteries and EDLC or not. With hybrid energy storage the batteries are less discharged because of presence of EDLC (particularly due to efficiency difference) and their life cycle is longer. [less ▲]

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