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See detailEvaluation of long-term bedload virtual velocity in gravel-bed rivers (Ardenne, Belgium)
Houbrechts, Geoffrey ULg; Levecq, Yannick; Peeters, Alexandre ULg et al

in Geomorphology (2015), 251

In many gravel-bed rivers, bed material transfer has been interrupted or perturbed by anthropogenic activities. Currently, restoration projects are being conducted in many countries in order to re ... [more ▼]

In many gravel-bed rivers, bed material transfer has been interrupted or perturbed by anthropogenic activities. Currently, restoration projects are being conducted in many countries in order to re-establish bedload continuity. However, until now, few studies have provided indications of the velocity of bed material over the long-term (at least decade to century time-scale). In the context of river restoration projects (e.g. weir removal, addition of spawning gravel), these data are nevertheless crucial to predict the downstream propagation of the geomorphological and biological benefits (e.g. supply-transport equilibrium, morphological and substratum diversity). In our study, PIT-tag tracers were used in eight medium-sized gravel-bed rivers (Ardenne Region, Belgium) to propose a flow competence relationship based on specific stream power, on the one hand, and to determine the long-term virtual velocity of the bed material corresponding to the median diameter (D50) of the surface layer of riffles, on the other hand. After each flow event that exceeded the threshold for sediment entrainment, tagged particles were sought and located, even when they were buried in the subsurface layer. Afterwards, all of the data were used to estimate the virtual velocity of the bed material over the long-term using three approaches. Finally, the results were compared with long-term transport estimations based on iron slag dispersed by the rivers since the end of the middle ages. [less ▲]

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See detailEvaluation of long-term functional deficits following transient cerebral ischemia in two mouse strains
Fassotte, Ludivine ULg; Linden, Jérôme ULg; Ferrara, André ULg et al

Poster (2011, November 03)

Nowadays, no suitable animal model exists to assess long-term disabilities after cerebral ischemia. The aim of this study was to compare long-term behavioral and histological differences between two ... [more ▼]

Nowadays, no suitable animal model exists to assess long-term disabilities after cerebral ischemia. The aim of this study was to compare long-term behavioral and histological differences between two common mouse strains (129S2/SvPasCrl and C57BL6H) after 30 minutes of middle cerebral artery occlusion (MCAo). Sensorimotor assessments were conducted at one and at three weeks post-surgery using accelerated Rotarod and open-field locomotion. Long-term behavioral testing began four weeks after MCAo using operant conditioning in a progressive fixed-ratio (FR) schedule. Experiments ended with volumetric determination of the infarcted area using NeuN immunostaining. Although no effect of ischemia was detected in 129S2 mice using these tests, in C57 mice, results showed obvious short-term motor and locomotor deficits. Furthermore, subtle but persistent disturbances of endurance and executive functioning were recorded by the progressive schedule tests but not highlighted by sensorimotor tests. Ischemic lesion extended to the dorsolateral part of the striatum in both strains and recurrent cortical damages were also observed in C57 mice. All those results are in accordance with inherent morphological and behavioral features of each strain. Since the motor cortex is spared by 30 minutes MCAo, functional disabilities could be related to striatal damages. In conclusion, C57BL/6H mouse strain, by offering an acceptable survival rate and enough sensitivity to MCAo, seems to be a mouse strain suitable to evaluate long-term deficits and possible functional recovery after cerebral ischemia. [less ▲]

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See detailEvaluation of low-molecular-weight heparin for the prevention of equine laminitis after colic surgery
de la Rebière de Pouyade, Geoffroy ULg; Grulke, Sigrid ULg; Detilleux, Johann ULg et al

in Journal of Veterinary Emergency and Critical Care (2009), 19(1), 113-119

Objectives – The aim of this study is to describe the prevalence of postoperative laminitis in colic cases and to determine if low-molecular-weight heparin (LMWH) is effective in preventing this ... [more ▼]

Objectives – The aim of this study is to describe the prevalence of postoperative laminitis in colic cases and to determine if low-molecular-weight heparin (LMWH) is effective in preventing this complication. Design – Retrospective clinical study. Animals – Client-owned horses. Interventions – SC administration of enoxaparin during the postoperative period. Measurements and Main Results – Medical records of 360 horses undergoing surgery for colic and surviving at least 3 days were evaluated. Fifty-six horses admitted before 1995 did not receive LMWH (control group) and 304 admitted after 1995 received LMWH as a prophylaxis for laminitis (treatment group). Three grades of severity were defined for laminitis. Prevalence and severity of laminitis were compared between the 2 groups. Several parameters recorded on admission (sex, age, breed, site and nature of the disease, heart rate, PCV, gravity score, and shock score) and the administration of LMWH were tested as risk factors in the development of laminitis in a logistic regression procedure. Prevalence and grade of laminitis were significantly lower in the treatment group. Only the absence of LMWH was recognized as a significant risk factor in the logistic regression model. Conclusions – The administration of LMWH appears to be effective in the prophylaxis of laminitis following colic surgery and may be useful in the postoperative management of these horses. [less ▲]

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See detailEvaluation of Macrolophus pygmaeus as biocontrol agent aginst aphids
De Backer, Lara ULg

Master's dissertation (2012)

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See detailEvaluation of Matrix Metalloproteinases and Serine Proteases Activities in Three B16 Melanoma Cell Lines with Distinct Tumorigenic Potential
Baramova, E. N.; Coucke, P.; Leprince, Pierre ULg et al

in Anticancer Research (1994), 14(3A, May-Jun), 841-6

Mouse B16 melanoma cells (B16, parental line) and two derived clones either pigmented (B16P) or non pigmented (B16NP) were cultured as monolayers (2D) or on agar, as aggregates (3D). The productions of ... [more ▼]

Mouse B16 melanoma cells (B16, parental line) and two derived clones either pigmented (B16P) or non pigmented (B16NP) were cultured as monolayers (2D) or on agar, as aggregates (3D). The productions of gelatinases A and B (72 kDa and 92 kDa type IV collagenases) and their inhibitors (TIMP1 and TIMP2), plasminogen activators (PAs) and plasminogen activator inhibitors (PAI) were investigated. The B16 cell lines did not secrete any gelatinase, but they secreted TIMP2, tissue-type (t-PA), urokinase-type (u-PA) plasminogen activators and PAI-1 like activities. High levels of PAI activity were determined in conditioned media and cellular extracts of B16NP, which could account for the lower tumorigenic potential of these cells. In 3D cultures, the cellular extracts of the three cell lines contained essentially u-PA activity. This activity could contribute to the greater tumorigenic and invasive capacities of B16, B16P and B16NP when cultured in 3D. [less ▲]

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See detailEvaluation of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for second-generation lignin analysis
Richel, Aurore ULg; Vanderghem, Caroline ULg; Simon, Mathilde ULg et al

in Analytical Chemistry Insights (2012), 7

Matrix-Assisted Laser Desorption/Ionization time-of-flight (MALDI-TOF) mass spectrometry is evaluated as an elucidation tool for structural features and molecular weights estimation of some extracted ... [more ▼]

Matrix-Assisted Laser Desorption/Ionization time-of-flight (MALDI-TOF) mass spectrometry is evaluated as an elucidation tool for structural features and molecular weights estimation of some extracted herbaceous lignins. Optimization of analysis conditions, using a typical organic matrix, namely CHCA (alpha-cyano-4-hydroxycinnamic acid), in combination with alpha-cyclodextrine, allows efficient ionization of poorly soluble lignin materials and suppression of matrix-related ions background. Analysis of low-mass fragments ions (m/z 100-600) in the positive ion mode offers a “fingerprint” of starting lignins that could be a fine strategy to qualitatively identify principal interunit linkages between phenylpropanoid units. The molecular weights of lignins are estimated using size exclusion chromatography and compared to MALDI-TOF-MS profiles. Miscanthus (Miscanthus x giganteus) and Switchgrass (Panicum Virgatum L.) lignins, recovered after a formic acid/acetic acid/water process or aqueous ammonia soaking, are selected as benchmarks for this study. [less ▲]

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See detailEvaluation of medicinal plants from Reunion Island for antimalarial and cytotoxic activities
Jonville, Marie ULg; Kodja, H.; Humeau, L. et al

in Planta Medica (2008), 74(9), 1002-1002

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See detailEvaluation of morphological and functional characteristics of Carnobacterium maltaromaticum isolated from vacuum-packaged beef with long shelf life
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Ndedi Ekolo, François ULg et al

Poster (2014, October 17)

Carnobacterium maltaromaticum is a lactic acid bacterium, and many lactic acid bacteria associated with meat are known for their bactericidal or bacteriostatic activity against other strains, species or ... [more ▼]

Carnobacterium maltaromaticum is a lactic acid bacterium, and many lactic acid bacteria associated with meat are known for their bactericidal or bacteriostatic activity against other strains, species or genera of bacteria. The presence of certain lactic acid bacteria adapted to a low temperature in fresh meat could extend the shelf life and improve the microbial stability and safety of this product. The aim of this study was to perform a morphological and functional characterization of a C. maltaromaticum strain with a potential bioprotective effect isolated from vacuum packaged beef with very long shelf life. The morphological, biochemical and enzymatic profiles, the influence of different temperatures and atmospheres, and the microbial stability of fresh beef inoculated with the C. maltaromaticum strain were evaluated. The isolated C. maltaromaticum strain presented similar morphological, biochemical and enzymatic profiles as those of two reference strains (LMG 11393 and LMG 22902). Among the studied conditions, a temperature of +12 °C and an atmosphere poor in oxygen were optimal for the growth of C. maltaromaticum. Vacuum packing is therefore suitable for this bacterium. An antimicrobial effect against Enterobacteriaceae was highlighted on inoculated fresh meat stored under N2. The functional characterization of this isolate will be further pursued by a genotypic characterization. Special attention will be taken to study its bioprotective properties. [less ▲]

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See detailEvaluation of network equivalents for voltage optimization in multi-area power systems
Phulpin, Yannick; Miroslav, Begovic; Petit, Marc et al

in IEEE Transactions on Power Systems (2009), 24(2), 729-743

The paper addresses the problem of decentralized optimization for a power system partitioned into several areas controlled by different transmission system operators (TSOs). The optimization variables are ... [more ▼]

The paper addresses the problem of decentralized optimization for a power system partitioned into several areas controlled by different transmission system operators (TSOs). The optimization variables are the settings for taps, generators’ voltages and compensators’, and the objective function is either based on the minimization of reactive power support, the minimization of active power losses, or a combination of both criteria. We suppose that each TSO assumes an external network equivalent for its neighboring areas and optimizes without concern for the neighboring systems’ objectives its own optimization function. We study, in the context where every TSO adopts the same type of objective function, the performance of an iterative scheme, where every TSO refreshes at each iteration the parameters of its external network equivalents depending on its past internal observations, solves its local optimization problem, and then, applies its “optimal actions” to the power system. In the context of voltage optimization, we find out that this decentralized control scheme can converge to nearly optimal global performance for relatively simple equivalents and simple procedures for fitting their parameters. [less ▲]

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See detailEvaluation of Non-negative matrix Factorization of grey matter in age prediction
Varikuti, Deepthi; Genon, Sarah ULg; 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 ▲]

Detailed reference viewed: 31 (2 ULg)