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See detailFine structure of the larvae of the Myzostoma cirriferum (Myzostomida)
Eeckaut, I.; Fievez, Laurence ULg; Jangoux, M.

Poster (1998)

Adults of Myzostoma cirriferum are obligate ectocommensals that live on the surface of comatulids of the genus Antedon from the North East Atlantic and Mediterranean. M. cirriferum is a simultaneous ... [more ▼]

Adults of Myzostoma cirriferum are obligate ectocommensals that live on the surface of comatulids of the genus Antedon from the North East Atlantic and Mediterranean. M. cirriferum is a simultaneous hermaphrodite which reproduces by transferring spermatophores that penetrate the integument of the receiver myzostomes. Fertilized eggs are shed into the water column where they divide. After the embryonic stage that lasts 24h, the motile individuals enter into the larval stage. Three types of larvae are recognized in M. cirriferum: the spherical protrochophora (occuring between 24 and 48h after the laying), the pyriform trochophora (48-72h), and the pyriform, setigerous metatrochophora (72h until metamorphosis). The body of the protrochophora and trochophora is made of undifferenciated cells and ciliated cells. Two types of undifferentiated cells are present: the first contact the thin cuticle, have microvilli and include a lot of yolk droplets; the second are internal and have no or only a few yolk droplets. No basal lamina has been observed in the body of these larvae. Huge tissular modifications occur in the young metatrochophora (i.e. 96-144h after laying). The epidermis is now well underlined by a basal lamina. Two pairs of 4 chaetae lie on the sides of the larval body and a sensory caudal appendage is differentiating at its end. The digestive system is forming. It is composed of a pharynx included in an extensible introvert and a closed, internal digestive cavity. The nervous system appears and is composed of an epispheral nervous mass, a peripharyngeal collar, nervous processes and sensory cells. The anatomy of the late metatrochophora stays unchanged until metamorphosis, which generally occurs 7 days after laying. The body of the larva is made of twelve cell types. Seven are ectodermal: covering cells and ciliated cells make up most of the epidermis; primary chaetoblasts and lateral cells form the chaetal follicles; secondary chaetoblasts will build the chaetae of juveniles after metamorphosis; pharyngeal cells and myoepithelial cells make up the pharyngeal epithelium. The other cell types are neurodermal (neurons and sensory cells), endodermal (the digestive cells that border the digestive cavity) and mesodermal (parenchyma cells and muscle cells) [less ▲]

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See detailFine-mapping and construction of a bovine contig spanning the ovine callipyge locus.
Shay, T. L.; Berghmans, S.; SEGERS, Karin ULg et al

in Mammalian Genome : Official Journal of the International Mammalian Genome Society (2001), 12(2), 141-9

The callipyge (CLPG) gene was fine-mapped by linkage analysis to a 4.6-cM chromosome interval on distal ovine OAR18q, flanked by microsatellite markers IDVGA30 and OY3. The OAR18q linkage map and human ... [more ▼]

The callipyge (CLPG) gene was fine-mapped by linkage analysis to a 4.6-cM chromosome interval on distal ovine OAR18q, flanked by microsatellite markers IDVGA30 and OY3. The OAR18q linkage map and human HSA14q transcript map were aligned by genotyping two bovine-hamster whole-genome radiation hybrid panels with the microsatellite markers, as well as with sequences corresponding to HSA 14q genes. Using Type I loci mapping to the IDVGA30-OY3 interval as anchor points, we have constructed a 1.4-Mb bovine BAC contig containing the IDVGA30-OY3 interval. We demonstrate that the IDVGA30-OY3 interval spans approximately 770 kb and contains at least four genes: YY1, WARS, DLK1, and GTL2. [less ▲]

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See detailFine-Mapping of Quantitative Trait Loci by Identity by Descent in Outbred Populations: Application to Milk Production in Dairy Cattle
Riquet, J.; Coppieters, Wouter ULg; Cambisano, Nadine ULg et al

in Proceedings of the National Academy of Sciences of the United States of America (1999), 96(16), 9252-9257

We previously mapped a quantitative trait locus (QTL) affecting milk production to bovine chromosome 14. To refine the map position of this QTL, we have increased the density of the genetic map of ... [more ▼]

We previously mapped a quantitative trait locus (QTL) affecting milk production to bovine chromosome 14. To refine the map position of this QTL, we have increased the density of the genetic map of BTA14q11-16 by addition of nine microsatellites and three single nucleotide polymorphisms. Fine-mapping of the QTL was accomplished by a two-tiered approach. In the first phase, we identified seven sires heterozygous "Qq" for the QTL by marker-assisted segregation analysis in a Holstein-Friesian pedigree comprising 1,158 individuals. In a second phase, we genotyped the seven selected sires for the newly developed high-density marker map and searched for a shared haplotype flanking an hypothetical, identical-by-descent QTL allele with large substitution effect. The seven chromosomes increasing milk fat percentage were indeed shown to carry a common chromosome segment with an estimated size of 5 cM predicted to contain the studied QTL. The same haplotype was shown to be associated with increased fat percentage in the general population as well, providing additional support in favor of the location of the QTL within the corresponding interval. [less ▲]

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See detailFine-scale analysis of ungulate-vehicle collisions in Southern Belgium
maron, Julie; Lehaire, François ULg; Morelle, Kevin ULg et al

Poster (2013, August)

Ungulate-vehicle collisions (UVC) are an increasing phenomenon in many European countries. These road accidents are a threat to wildlife populations but also to human safety and generate high economic ... [more ▼]

Ungulate-vehicle collisions (UVC) are an increasing phenomenon in many European countries. These road accidents are a threat to wildlife populations but also to human safety and generate high economic costs. Wallonia, the Southern part of Belgium, is also affected by the UVC problem and offers an interesting study area because of its very dense road network and increasing big game populations. The aim of our study was to determine where and when UVC hotspots occurred along highways in Wallonia, in order to provide recommendations regarding the location and design of mitigation measures. The study site is located in Wallonia (Southern Belgium) in the provinces of Liege and Namur (5,875 km²). Ungulates species present in this area are wild boar, roe deer and red deer. The UVC data were collected by the police and covered the period between 2008 and 2011 (n= 2,704). We analyzed the landscape and road-related variables of sections with high UVC risk in contrast with section of low risk. The landscape and road-related variables related to the location of UVC were highlighted using a generalized linear model (GLM) with simulated pseudo-absences. Concerning traffic accidents, the most involved game species are wild boar (37% of all casualties). That’s why the amount of data on wild boar was higher than for the other species. The results of the spatial and temporal analysis of wild boar-vehicle collisions (WVC) are therefore more accurate than for the other species. Consequently we decided to focused on the wild boar in the present poster. Temporal analysis showed strong variations in the WVC frequency over time, on the daily and seasonal scale. These critical periods correspond to the activity periods of the species (more UVC at night and during autumn and winter). The study also points out a negative correlation between the occurrence of UVC and the traffic volume (R² = 9.79%). This result doesn’t match with the literature but can be explained if we assume that when traffic increase, the road represents a more impassable barrier for animal species. As expected we also noticed a positive correlation between game density and UVC risk. These results indicate clear spatial and temporal clustering of WVC. Identification of hotspots enables us to identify the priority areas where mitigation measures must be considered. For further research, the accuracy of the police data should be improved in order to predict more exactly the risk of UVC. This would also make the mitigation measures more cost-effective. [less ▲]

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See detailFINE-SCALE HABITAT SELECTION BY TWO SPECIALIST WOODPECKERS OCCURRING IN BEECH AND OAK-DOMINATED FORESTS IN SOUTHERN BELGIUM
Delahaye, Laurence; Monticelli, David; Lehaire, François ULg et al

in Ardeola (2010), 57(2), 339-362

We studied the identification of key habitat parameters for two specialist woodpecker species (middle spotted woodpecker Dendrocopos medius and lesser spotted woodpecker D. minor) associated with mature ... [more ▼]

We studied the identification of key habitat parameters for two specialist woodpecker species (middle spotted woodpecker Dendrocopos medius and lesser spotted woodpecker D. minor) associated with mature broadleaved forests ecosystems in Europe, and the modelling of their specific requirements with a view to assist forest managers. The study was conducted in four beech and oak-dominated forests (Haut-Fays, Halma, Gembes and Croix-Scaille) located in the Ardennes Region of Southern Belgium. The study sites covered a total area of ca. 20 km². A census of woodpecker occurrence (presenceabsence) was implemented from 2000 to 2003 within 255 1-ha plots. Habitat variables describing stand age, tree density, snag density, stand composition and vertical vegetation structure were also sampled at the same plots to develop both logistic and autologistic regression models describing habitat use.Middle spotted woodpecker (MSW) uses the oak-rich locations (mean basal area of 15.6 m²/ha), with selection of areas with the largest, oldest oak trees (mean circumference > 150 cm), and with a high diversity of tree species in the overstory. Similarly, the lesser spotted woodpecker (LSW) was detected in areas presenting the highest percentage cover of oak trees but with a selection of younger stands, with a high density of snags and dead wood (mean of 9 m³/ha). The integration of an autocorrelation term improved model performance for the LSW but not for MSW. Our results highlight the importance of a high disponibility of oak trees for these two sympatric species. The climax forest in northwest Europe is beech so that public and private owners must develop appropriate forest management plans to prevent the conversion of oak to beech forests. In particular, forest managers can promote an active oakregeneration management to obtain a balanced representation of age classes. They must also aim to maintain/increase the volume of dead wood resources by reserving all trees produced by storms or any other cause of natural mortality. [less ▲]

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See detailFine-scale spatial pattern of Cleistogenes squarrosa population under different grazing intensities.
Liu, Z.; Li, Z.; Nijs, I. et al

in Acta Prataculturae Sinica = Caoye xuebao (2005), 14(1), 11-17

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See detailFinger Tapping feature extraction in Parkinson's disease using low-cost accelerometers
Stamatakis, Julien; Cremers, Julien ULg; Macq, Benoït et al

in Proceedings 10th IEEE International Conference on Information Technology and Applications in Biomedicine (ITAB 2010) (2010)

The clinical hallmarks of Parkinson's disease (PD) are movement poverty and slowness (i.e. bradykinesia), muscle rigidity and limb tremor. The physicians usually quantify these motor disturbances by ... [more ▼]

The clinical hallmarks of Parkinson's disease (PD) are movement poverty and slowness (i.e. bradykinesia), muscle rigidity and limb tremor. The physicians usually quantify these motor disturbances by assigning a severity score according to validated but time-consuming clinical scales such as the Unified Parkinson's Disease Rating Scale (UPDRS) - part III. These clinical ratings are however prone to subjectivity and inter-rater variability. The PD medical community is therefore looking for a faster and more objective rating method. As a first step towards this goal, a tri-axial accelerometer-based system is proposed as patients are engaged in a repetitive finger tapping task, which is classically used to assess bradykinesia in the UPDRS-III. After developing the hardware, an algorithm has been developed, that automatically epoched the signal on a trial-by-trial basis and quantified, among others, movement speed, amplitude, hesitations or halts as validated by visual inspection of video recordings during the task. The results obtained in a PD patient and an healthy volunteer are presented. Preliminary results show that PD patients and healthy volunteers have different features profiles, so that a classifier could be set up to predict objective UPDRS-III scores. [less ▲]

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See detailFinishing of the Belgian Blue double-muscled cull female: influence of age and dietary energy level
Cabaraux, Jean-François ULg

in Annales de Médecine Vétérinaire (2005), 149(Sp. Iss. SI), 1-4

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See detailFinit element modelling of an asynchronous motor with one broken rotor bar, comparison with the data recorded on a prototype and material aspects
Guérard, Suzanne ULg; Gyselinck, Johan; Lecomte-Beckers, Jacqueline ULg

in Bulletin Scientifique de l'AIM (Association des Ingénieurs Electriciens sortis de l'Institut Electrotechnique Montefiore) (2005), 1

This work studies the problem of broken rotor bars in cage induction motors. To this aim, an induction machine from WEG Motors was modelled by means of the finite element method. The motor modelled is a ... [more ▼]

This work studies the problem of broken rotor bars in cage induction motors. To this aim, an induction machine from WEG Motors was modelled by means of the finite element method. The motor modelled is a 18.5 kW four-pole induction motor with a straight rotor cage. The field distribution and stator phase currents were computed for a motor without broken rotor bars and for a motor with one broken rotor bar. The computed stator phase currents were compared to the ones recorded on motors respectively no broken rotor bar and with one broken rotor bar. The FE model and an equivalent scheme of the motor permitted to show that the resistance of the rotor cage was higher than expected, considering only the temperature effect on the conductivity of the rotor bars. A metallurgic analysis of the aluminium alloy of two rotor bars revealed the presence of a very high density of silicon and silicon oxide inclusions, as well as the presence of shrinkages and cracks, which have a negative impact on both conductivity and mechanical strength. A corrected value of the rotor bar conductivity was used in the finite element model and led to a good agreement with the experimental results. The field perturbation associated with a broken rotor bar produces a concentration of flux near the bar ahead of the broken one, considering the counterclockwise direction of rotation of the rotor. This flux concentration results in higher current values and hence in higher stresses in the bar ahead of the broken one. [less ▲]

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See detailFinite difference and finite element modelling of an aquifer in Cretaceous chalk
Bolly, Pierre-Yves; Dassargues, Alain ULg; Monjoie, Albéric ULg

in Proceedings of the sixth International Conference on Numerical Methods in Geomechanics (1988, April)

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See detailFinite element analysis of continuous steel casting
Castagne, S.; Pascon, Frédéric ULg; Miesse, G. et al

in Proceedings of the First International Conference Finite element for process analysis (2003)

In order to analyse the behaviour of steel during continuous casting and to improve the process, two complementary models of steel continuous casting using the finite element code LAGAMINE have been ... [more ▼]

In order to analyse the behaviour of steel during continuous casting and to improve the process, two complementary models of steel continuous casting using the finite element code LAGAMINE have been developed. We propose here a description of both macroscopic and mesoscopic approaches. The first one describes the whole continuous casting process, from the free surface in the mould and through the entire machine, including thermal and mechanical behaviour of the steel. The second approach focuses on the prediction of cracks and is developed at the grain scale. Results concerning the optimisation of the mould taper and the analysis of transverse cracks initiation are presented as industrial applications. [less ▲]

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See detailA finite element analysis of spatial solitons in optical fibres
Nicolet, A.; Drouart, F.; Renversez, G. et al

in Proceedings of the XIX Symposium on Electromagnetic Phenomena in Nonlinear Circuits (EPNC 2006) (2006)

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See detailA finite element analysis of spatial solitons in optical fibres
Drouart, F.; Nicolet, A.; Renversez, G. et al

in Proceedings of the 7th conference on Electrical, Transport and Optical Properties of Inhomogeneous Media (ETOPIM 7) (2006, July)

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See detailA finite element analysis of spatial solitons in optical fibres
Nicolet, A.; Drouart, F.; Renversez, G. et al

in COMPEL (2007), 26(4), 1105--1113

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See detailFinite element analysis of strongly nonlinear phenomena in deployable flexible systems
Bruls, Olivier ULg; Hoffait, Sébastien ULg; Cugnon, Frederic et al

in 1st ESA Multibody Dynamics Workshop on Multibody Dynamics for Space Applications, Noordwijk, 2010 (2010)

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See detailA finite element analysis of the bending and the bendability of metallic sheets
Ben Bettaieb, Mohamed ULg; Lemoine, Xavier; Bouaziz, O. et al

in International Journal of Material Forming (2011), 4(3), 283-297

The main objective of this paper is to study the bendability of metallic sheets by using the finite element method. In this aim, two variants of an advanced Gurson-Tvergaard-Needleman model [1, 2] are ... [more ▼]

The main objective of this paper is to study the bendability of metallic sheets by using the finite element method. In this aim, two variants of an advanced Gurson-Tvergaard-Needleman model [1, 2] are implemented in the home made FE code LAGAMINE [3, 4] and coupled with the Thomason model to predict the coalescence of voids. This advanced model is an extension of the original one to take into account of the plastic anisotropy and the mixed (isotropic + kinematic) hardening of the matrix. The difference between the two variants is related to the modeling of the damage evolution. As the advanced model is used to study the bending process, its yield function is slightly modified in order to take into account the loadings with negative triaxiality ratios. These present implementations are used to simulate the pure bending process and to predict the bendability of dual phase (DP) steel. The combined effect of an initial geometrical imperfection and damage evolution on the bendability is also studied. [less ▲]

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See detailFinite Element Analysis of the Electro-Mechanical Coupling in MEMS
Rochus, Véronique ULg; Duysinx, Pierre ULg; Golinval, Jean-Claude ULg

Conference given outside the academic context (2002)

This paper concerns the modelling of the strong electro-mechanical coupling appearing in micro-electro-mechanical systems (MEMS). These systems are very small devices (typical size of a few microns), in ... [more ▼]

This paper concerns the modelling of the strong electro-mechanical coupling appearing in micro-electro-mechanical systems (MEMS). These systems are very small devices (typical size of a few microns), in which electric phenomena as well as mechanical and dynamical phenomena exist. The coupling between the electric and mechanical fields induce non-linear terms in the dynamic equilibrium equations of these microscopic structures so that instability may occur. In this paper, the finite element method (FEM) is used to perform modal analysis around non-linear equilibrium positions, taking into account large displacements. [less ▲]

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See detailFinite element analysis of the free surface effects on the mechanical behavior of thin nickel polycrystals
Keller, Clément ULg; Hug, eric; Habraken, Anne ULg et al

in International Journal of Plasticity (2012), 29

The miniaturization of metallic samples has been proved to deeply affect their mechanical properties leading to a softening or a hardening effect depending on the order of the dimension reduction. The ... [more ▼]

The miniaturization of metallic samples has been proved to deeply affect their mechanical properties leading to a softening or a hardening effect depending on the order of the dimension reduction. The objective of this work is to provide new numerical results which explain the softening mechanisms on the mechanical behavior for nickel polycrystals which have been experimentally characterized by the authors in a previous published paper (Keller et al., 2011). Based on a strain gradient crystalline plasticity model identified for nickel, simulations of tensile tests were performed for samples with different thicknesses and grain sizes. The simulations correctly reproduce the softening effect linked to a decrease in the thickness and in the number of grains across the thickness. The analysis of the plasticity mechanisms shows that the softening is due to surface effects which are discussed in terms of grain orientations, dislocation mean free path and long-range back-stress. The model also predicts a hardening mechanism for further dimension reduction if the samples have only grain boundaries perpendicular to the tensile direction. In this case, the modification of the mechanical behavior is due to strain gradients formation. [less ▲]

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See detailFinite element analysis on implicitly defined domains: An accurate representation based on arbitrary parametric surfaces
Moumnassi, Mohammed; Belouettar, Salim; Béchet, Eric ULg et al

in Computer Methods in Applied Mechanics & Engineering (2011), 200(5-8), 774-796

In this paper, we present some novel results and ideas for robust and accurate implicit representation of geometric surfaces in finite element analysis. The novel contributions of this paper are threefold ... [more ▼]

In this paper, we present some novel results and ideas for robust and accurate implicit representation of geometric surfaces in finite element analysis. The novel contributions of this paper are threefold: (1) describe and validate a method to represent arbitrary parametric surfaces implicitly; (2) represent arbitrary solids implicitly, including sharp features using level sets and boolean operations; (3) impose arbitrary Dirichlet and Neumann boundary conditions on the resulting implicitly defined boundaries. The methods proposed do not require local refinement of the finite element mesh in regions of high curvature, ensure the independence of the domain’s volume on the mesh, do not rely on boundary regularization, and are well suited to methods based on fixed grids such as the extended finite element method (XFEM). Numerical examples are presented to demonstrate the robustness and effectiveness of the proposed approach and show that it is possible to achieve optimal convergence rates using a fully implicit representation of object boundaries. This approach is one step in the desired direction of tying numerical simulations to computer aided design (CAD), similarly to the isogeometric analysis paradigm. [less ▲]

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