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See detailAssessment of a bone biopsy technique for measuring tiludronate in horses: A preliminary study
Delguste, Catherine ULg; Doucet, Michèle; Gabriel, Annick ULg et al

in Canadian Journal of Veterinary Research = Revue Canadienne de Recherche Vétérinaire (2011), 75(2), 128-133

Detailed reference viewed: 31 (13 ULg)
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See detailAssessment of a bone biopsy technique for tiludronic acid dosage in horses: a preliminary study
Delguste, Catherine ULg; Doucet, Michèle; Gabriel, Annick ULg et al

Poster (2006, September)

Introduction Tiludronic acid as a bisphosphonate has a strong affinity for bone, making difficult the assessment of its PK profile in this deep compartment on living animals. The invasive nature of sample ... [more ▼]

Introduction Tiludronic acid as a bisphosphonate has a strong affinity for bone, making difficult the assessment of its PK profile in this deep compartment on living animals. The invasive nature of sample collection remains a limiting factor. This study was carried out in order to assess a bone biopsy technique allowing the repetition of sampling over a long period of time to dose tiludronic acid in equine bone. Material and Methods Six healthy 4- to 8-year-old Standardbred geldings were treated with tiludronic acid 1 mg/kg in a saline infusion over 30 minutes. The horses were subjected to euthanasia on days 1, 43, 57, 92, 182 and 222 post-treatment, respectively. Bone samples (test samples and larger reference samples) were taken at 4 sites per side and per horse: the lateral aspect of the metacarpal bone III (MCIII) of the forelimb, the 13th rib, the tuber coxae and the cuboïd bone. Test samples were taken with a 5-mm diameter dental drill (Implanteo™, Anthogyr), while larger reference samples were taken around the drill sample sites with an osteotome. All samples were taken immediately after euthanasia. Tiludronic acid concentrations were measured by HPLC with UV detection. Results The tuber coxae was the easiest site to sample. The sample site of the MCIII was easily accessible but due to the extreme hardness of the bone, the drill sampling was technically difficult to perform. Drill samples obtained from the 13th rib were very small, and the access more limited. Finally, the access to the cuboïd bone required considerable dissection, not performable in vivo. Extraction and dosage of tiludronic acid from the MCIII was difficult for technical reasons in most cases, in drill samples as well as in reference samples, and most (96%) of the values obtained were considered unreliable. This was also true for some samples from the 13th rib and from the cuboïd bone, to a lesser extent (42% of unreliable values for both sites). Moreover, for these two sample sites, less technical problems were encountered for the extraction and dosage of tiludronic acid in drill samples than in reference samples. No extraction or dosage problem was encountered with the tuber coxae samples. The ratio of tiludronic acid concentrations in drill versus reference samples ranged from 73% to 185% (mean: 124%), 65% to 208% (mean: 118%), and 26% to 110% (mean: 62%) respectively in the tuber coxae, 13th rib and cuboïd bone. In all but one horse, the highest concentrations in tiludronic acid were found in the tuber coxae, while the lowest values tended to be in the cuboïd bone at any time post-treatment. Tiludronic acid was still found in all bone samples 7 months after treatment. Discussion As previously reported with other tools, the drill tested in this study should permit to conveniently perform bone biopsies in the equine tuber coxae. This biopsy site would be the most appropriate for repeated sampling to dose tiludronic acid over time. This would help to design appropriate PK/PD studies with tiludronic acid in horses. This study also further confirms the long persistence of tiludronic acid in equine bone. [less ▲]

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See detailAssessment of a multiscale fatigue damage model associated with stress gradient effects
Duchene, Laurent ULg; Marmi, Abdeljalil ULg; Habraken, Anne ULg

Poster (2014, September)

The aim of this research work is to develop a finite element numerical tool able to predict accurately the fatigue life of mechanical components. These components can have complex geometries, they can be ... [more ▼]

The aim of this research work is to develop a finite element numerical tool able to predict accurately the fatigue life of mechanical components. These components can have complex geometries, they can be submitted to a complex loading, leading to a specific stress field with possible stress concentration. Additionally, the successive cycles of loading are not necessarily identical. It is expected that the numerical tool can handle these demanding constraints. In this respect, a multiaxial fatigue damage model was implemented in our home-made finite element code Lagamine. The finite element method permits to account for the actual geometry of the mechanical part and the loading for the stress computation in the whole structure. The formulation of the multiaxial fatigue model is able to capture: - The non linear damage accumulation for multiblock and variable cyclic loading, - The effect of the mean (hydrostatic) stress, - The effect of the cycles below the fatigue limit if the damage was previously initiated. Finally, the occurrence of stress concentration will significantly reduce the life time of the studied piece. However, it is well-known that the subsequent local degradation of the material will be partly compensated by an enhanced load carrying contribution of the surrounding material, favourably leading to a reduction of the crack propagation. The stress gradients computed with different techniques are incorporated in the model so as to account for such beneficial influence. The physical roots of this model depart from the mesoscopic length scale, where the damage evolution is related to the mesoscopic accumulated plastic strain. Therefore, the variables of the model are defined at both macroscopic and mesoscopic scales and a specific scale transition method was implemented, based on the well-known simplified Zarka method but used at the multiscale level. The predictive capabilities of this multiscale multiaxial model are assessed by means of comparison with the classical Lemaitre-Chaboche model (implemented in the same FE code with stress gradient effects). For both models, the material parameters were identified from SN tests on smooth specimens of Ti-6Al-4V alloy, while the predictions of the models are validated thanks to comparison with experimental tests on notched samples, with stress gradient effects. [less ▲]

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See detailassessment of acid base imbalances in horses suffering from atypical myopathy
Van Galen, Gaby ULg; Cerri, Simona ULg; Porter, Sarah et al

in proceedings AAEP 2011 (2011, November 11)

Detailed reference viewed: 59 (14 ULg)
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See detailAssessment of an anomaly detector for jet engine health monitoring
Borguet, Sébastien ULg; Léonard, Olivier ULg

in International Journal of Rotating Machinery (2011), 2011

The goal of module performance analysis is to reliably assess the health of the main components of an aircraft engine. A predictive maintenance strategy can leverage this information to increase ... [more ▼]

The goal of module performance analysis is to reliably assess the health of the main components of an aircraft engine. A predictive maintenance strategy can leverage this information to increase operability and safety as well as to reduce costs. Degradation undergone by an engine can be divided into gradual deterioration and accidental events. Kalman filters have proven very efficient at tracking progressive deterioration but are poor performers in the face of abrupt events. Adaptive estimation is considered as an appropriate solution to this deficiency. This paper reports the evaluation of the detection capability of an adaptive diagnosis tool on the basis of simulated scenarios that may be encountered during the operation of a commercial turbofan engine. The diagnosis tool combines a Kalman filter and a secondary system that monitors the residuals. This auxiliary component implements a generalised likelihood ratio test in order to detect abrupt events. [less ▲]

Detailed reference viewed: 19 (2 ULg)
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See detailAssessment of asphalt concrete acoustic performance in urban streets
Paje, S.E.; Bueno, M.; Terán, F. et al

in Journal of acoustical society of america (2008), 123(3), 1439-1445

Geo-referenced close proximity rolling noise and sound absorption measurements are used for acoustical characterization of asphalt concrete surfaces in an urban environment. A close proximity noise map of ... [more ▼]

Geo-referenced close proximity rolling noise and sound absorption measurements are used for acoustical characterization of asphalt concrete surfaces in an urban environment. A close proximity noise map of streets with low speed limits is presented for a reference speed of 50 km/h. Different pavements and pavement conditions, common in urban streets, are analyzed: dense and semidense asphalt concrete, with Spanish denomination D-8 and S-12, respectively, and on the other hand, dense pavement at the end of its service life 􏰁D-8*􏰀. From the acoustics point of view, the most favorable surface, by more than 4 dB􏰁A􏰀 compared with the S-12 mix, is the smoothest surface, i.e., the D-8 mix, even though it presents a minor absorption coefficient in normal incidence. Noise levels from dense surfaces 􏰁D-8􏰀 increase significantly over time, principally due to the appearance of surface defects such as cracks and ruts. Longitudinal variability of the close proximity tire/ pavement noise emission and surface homogeneity are also analyzed. [less ▲]

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See detailAssessment of bacterial persistence in mosquitoes according to microinjection assays in Belgium
Raharimalala, Fara Nantenaina ULg; Bawin, Thomas ULg; Boukraa, Slimane ULg et al

Poster (2013, October 02)

The problems caused by the massive used of pesticides have resulted in the establishment of resistant vectors besides the destruction of the environment. Furthermore, climate change has consequently ... [more ▼]

The problems caused by the massive used of pesticides have resulted in the establishment of resistant vectors besides the destruction of the environment. Furthermore, climate change has consequently modified the comportment of disease vectors. Current research tends to look for alternative means to overcome the problem. The goal of that study was to undertaken the way there this objective. By their presence or absence, endosymbiotic microorganisms can influence vector competence and vectorial capacity. Our research aims to study the effect of the introduction of endosymbiotic bacteria in the mosquito species that could be potential vectors of disease in Belgium. Method used was the microinjection of endosymbiotic bacteria within the detected exempt mosquito species. Three genus of suspected vectors belonging to Aedes, Anopheles and Culex were microinjected at different stages of their life cycle (eggs, larvae, pupae, and adults), and survivability of mosquitoes and persistence of microorganism were determined. Results show that survival in the different stages was variable. Furthermore, persistence of endobacteria was different depending genus and stages studied [less ▲]

Detailed reference viewed: 57 (24 ULg)
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See detailAssessment of benefits of joint use of multiple medical imaging modalities: case of 3D neuroimaging
Vigneron, Lara M.; Verly, Jacques ULg

Conference (2002, June)

Detailed reference viewed: 5 (0 ULg)
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See detailAssessment of bioinformatic pipelines for the analysis of 454 pyrosequencing data using artificial cyanobacterial communities
Stelmach Pessi, Igor ULg; De Carvalho Maalouf, Pedro; Laughinghouse IV, Haywood ULg et al

Poster (2013, November 27)

The field of microbial ecology has undergone a revolution with the advent of next-generation sequencing (NGS) technologies, which revealed a higher microbial diversity than what was previously observed ... [more ▼]

The field of microbial ecology has undergone a revolution with the advent of next-generation sequencing (NGS) technologies, which revealed a higher microbial diversity than what was previously observed. The possibility of analyzing tens to hundreds of thousands sequences in a single sequencing run has provided information on rare taxa that could constitute an important fraction of microbial communities. However, this comes with the cost of relatively high error rates for individual reads, which can lead to overestimation of diversity due to the generation of spurious Operational Taxonomic Units (OTUs) consisting of erroneous sequences. Therefore, a correct assessment of microbial diversity using NGS relies on robust bioinformatic tools in order to correct for PCR and sequencing biases. Here we report on community structures recovered for two artificial cyanobacterial communities applying three commonly used and two recently published bioinformatic pipelines. This pilot study was made in the frame of the BELSPO project CCAMBIO. Artificial communities were constructed using DNA isolated from 22 cyanobacterial strains from the BCCM/ULC Polar Cyanobacteria Collection (http://bccm.belspo.be/about/ulc.php). DNA was extracted from individual cultures and pooled at equal (community Art1) or tiered (community Art2) concentrations. The V3-V4 hypervariable region of the 16S rRNA gene was amplified by PCR using primers 359F and 781Ra/781Rb [Nübel et al (1997) Appl Environ Microbiol 63: 3327-3332], and amplicons were sequenced on a 454 GS FLX Titanium platform. Data was demultiplexed and submitted to five bioinformatic pipelines for quality control of reads, removal of chimeric sequences and Operational Taxonomic Units (OTUs) clustering: (I) “shhh.flows (450 flows)”, (II) “shhh.flows (360-720 flows)” and (III) “Sliding Window (Q35, 50 bp)”, using MOTHUR according to Schloss et al (2011) [Schloss et al (2011) PLOS One 6: e27310]; (IV) “fastq_maxee” and (V) “fastq_truncqual”, using UPARSE according to Edgar (2013) [Edgar (2013) Nat Methods 10: 996-998]. Average sequence length varied considerably among pipelines, with pipeline I generating shorter reads (220 bp in average) and pipelines IV and V longer reads (370 bp). The number of OTUs obtained in each pipeline also varied significantly. While 22 and 21 OTUs were obtained for pipelines IV and V, respectively, pipelines I-III generated a surprisingly high number of OTUs (199, 317 and 289, respectively). Despite differences in the number of OTUs, the relative abundance of each reference strain did not differ significantly between pipelines. Overall, community structures observed using the UPARSE protocol (pipelines IV and V) were the most consistent with the expected results. These findings show the importance of assessing the performance of different bioinformatic pipelines using artificial communities, in order to reduce the effects of PCR and sequencing errors, which can lead to distorted community structures estimates. [less ▲]

Detailed reference viewed: 111 (10 ULg)
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See detailAssessment of bovine tuberculosis risk factors based on nationwide molecular epidemiology
Humblet, Marie-France ULg; Gilbert, M.; Govaerts, M. et al

in Journal of Clinical Microbiology (2010)

Detailed reference viewed: 18 (9 ULg)
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See detailAssessment of changes in soil organic matter after invasion by exotic plant species
Koutika, Lydie*-Stella; Vanderhoeven, SONIA ULg; Chapuis-Lardy, Lydie et al

in Biology & Fertility of Soils (2007), 44(2), 331-341

Invasive exotic plants can modify soil organic matter (SOM) dynamics and other soil properties. We evaluated changes in particulate organic matter (POM) and carbon (C) mineralisation in adjacent plots ... [more ▼]

Invasive exotic plants can modify soil organic matter (SOM) dynamics and other soil properties. We evaluated changes in particulate organic matter (POM) and carbon (C) mineralisation in adjacent plots invaded by Solidago gigantea, Prunus serotina, Heracleum mantegazzianum and Fallopia japonica, and non-invaded control plots on different soils in Belgium. Litter decomposition of S. gigantea and P. serotina was compared to that of the native species Epilobium hirsutum, Betula pendula and Fagus sylvatica. Disregarding the differences in site characteristics (soil texture, parental material and plant species), we argued that the invasion by S. gigantea and P. serotina enhance SOM dynamics by increasing C mineralisation in 2 out of 3 sites invaded by S. gigantea and in 1 out of 3 sites invaded by P. serotina; C in coarse POM (cPOM, 4,000-250 mu m) and fine POM (fPOM, 250-50 mu m) in 1 site invaded by S. gigantea and C content in total POM (tPOM, 4,000-50 mu m) and the organo-mineral fraction (OMF, 0-50 mu m) in 1 site invaded by P. serotina. H. mantegazzianum and F. japonica slowed down SOM dynamics by reducing C mineralisation in three out of four sites; C and nitrogen (N) of fPOM in the invaded compared with the non-invaded plots at one site invaded by H. mantegazzianum. However, N content of cPOM (4,000-250 mu m) was higher in the invaded sites by F. japonica compared with the non-invaded plots. Our results indicated that the effects of invasion by exotic plant species were not species-specific but site-specific. [less ▲]

Detailed reference viewed: 27 (2 ULg)
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See detailAssessment of Complex Perineal Fistulas
Bruyninx, Luc ULg; Meunier, Paul ULg

in Acta Chirurgica Belgica (2000), 100(3, May-Jun), 115-7

Detailed reference viewed: 9 (0 ULg)
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See detailAssessment of conceptual model uncertainty for the regional aquifer Pampa del Tamarugal – North Chile
Rojas, Rodrigo; Batelaan, Okke; Feyen, Luk et al

in Hydrology and Earth System Sciences (2010), 14

In this work we assess the uncertainty in modelling the groundwater flow for the Pampa del Tamarugal Aquifer (PTA) – North Chile using a novel and fully integrated multimodel approach aimed at explicitly ... [more ▼]

In this work we assess the uncertainty in modelling the groundwater flow for the Pampa del Tamarugal Aquifer (PTA) – North Chile using a novel and fully integrated multimodel approach aimed at explicitly accounting for uncertainties arising from the definition of alternative conceptual models. The approach integrates the Generalized Likelihood Uncertainty Estimation (GLUE) and Bayesian Model Averaging (BMA) methods. For each member of an ensemble M of potential conceptualizations, model weights used in BMA for multi-model aggregation are obtained from GLUE-based likelihood values. These model weights are based on model performance, thus, reflecting how well a conceptualization reproduces an observed dataset D. GLUE-based cumulative predictive distributions for each member of M are then aggregated obtaining predictive distributions accounting for conceptual model uncertainties. For the PTA we propose an ensemble of eight alternative conceptualizations covering all major features of groundwater flow models independently developed in past studies and including two recharge mechanisms which have been source of debate for several years. Results showed that accounting for heterogeneities in the hydraulic conductivity field (a) reduced the uncertainty in the estimations of parameters and state variables, and (b) increased the corresponding model weights used for multi-model aggregation. This was more noticeable when the hydraulic conductivity field was conditioned on available hydraulic conductivity measurements. Contribution of conceptual model uncertainty to the predictive uncertainty varied between 6% and 64% for ground water head estimations and between 16% and 79% for ground water flow estimations. These results clearly illustrate the relevance of conceptual model uncertainty. [less ▲]

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See detailAssessment of consciousness with electrophysiological and neurological imaging techniques.
Bruno, Marie-Aurélie ULg; Gosseries, Olivia ULg; Ledoux, Didier ULg et al

in Current Opinion in Critical Care (2011)

PURPOSE OF REVIEW: Brain MRI (diffusion tensor imaging and spectroscopy) and functional neuroimaging (PET, functional MRI, EEG and evoked potential studies) are changing our understanding of patients with ... [more ▼]

PURPOSE OF REVIEW: Brain MRI (diffusion tensor imaging and spectroscopy) and functional neuroimaging (PET, functional MRI, EEG and evoked potential studies) are changing our understanding of patients with disorders of consciousness encountered after coma such as the 'vegetative' or minimally conscious states. RECENT FINDINGS: Increasing evidence from functional neuroimaging and electrophysiology demonstrates some residual cognitive processing in a subgroup of patients who clinically fail to show any response to commands, leading to the recent proposal of 'unresponsive wakefulness syndrome' as an alternative name for patients previously coined 'vegetative' or 'apallic'. SUMMARY: Consciousness can be viewed as the emergent property of the collective behavior of widespread thalamocortical frontoparietal network connectivity. Data from physiological, pharmacological and pathological alterations of consciousness provide evidence in favor of this hypothesis. Increasing our understanding of the neural correlates of consciousness is helping clinicians to do a better job in terms of diagnosis, prognosis and finally treatment and drug development for these severely brain-damaged patients. The current challenge remains to continue translating this research from the bench to the bedside. Only well controlled large multicentric neuroimaging and electrophysiology studies will enable to identify which paraclinical diagnostic or prognostic test is necessary for our routine evidence-based assessment of individuals with disorders of consciousness. [less ▲]

Detailed reference viewed: 117 (10 ULg)