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See detailFlux des sédiments en suspension dans les rivières du bassin de la Meuse : proposition d'une typologie régionale basée sur la dénudation spécifique des bassins versants
Van Campenhout, Jean ULg; Hallot, Eric ULg; Houbrechts, Geoffrey ULg et al

Poster (2013, October 15)

L'érosion des sols peut être appréhendée à l'échelle du bassin versant en quantifiant le transport sédimentaire en suspension à son exutoire. Environ 2.000 mesures de concentration des matières en ... [more ▼]

L'érosion des sols peut être appréhendée à l'échelle du bassin versant en quantifiant le transport sédimentaire en suspension à son exutoire. Environ 2.000 mesures de concentration des matières en suspension ont permis d'estimer les débits solides annuels en fonction des débits liquides observés dans ces cours d'eau. Une méthodologie simple a été mise en place et appliquée à un réseau de 80 stations, à l’exutoire de bassins versants d’une superficie comprise entre 16 et 2.900 km² situées en région wallonne. Des différenciations régionales ont pu être mises en évidence en fonction du substrat et de l'occupation du sol des bassins versants. La granulométrie des particules transportées et la proportion de matière organique complètent l'analyse et confirment les différenciations observées selon les régions agro-géographiques. L’impact de la fréquence d’échantillonnage (et de sa synchronisation avec les débits de crue) sur l’estimation de la dénudation annuelle a été mis en évidence, ainsi que la grande variabilité interannuelle, qui est fonction de l’intensité et de la hauteur des précipitations. L’érosion des sols est ainsi très sensible aux événements extrêmes. Par ailleurs, l’intérêt de longues campagnes de mesures est souligné. Des données issues de travaux antérieurs ont également été intégrées à la base de données. Son interprétation a permis de définir les meilleurs sites susceptibles d’accueillir à long terme un réseau de mesure en continu de la concentration des matières en suspension en Wallonie. [less ▲]

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See detailCaractérisation de la couche active et du débit solide dans les rivières à charge caillouteuse du massif ardennais
Levecq, Yannick ULg; Houbrechts, Geoffrey ULg; Van Campenhout, Jean ULg et al

Poster (2013, October 15)

Plusieurs techniques existent pour calculer l’épaisseur de la couche active de charriage et le débit solide des rivières. Il peut s’agir de chaînes d’érosion, de pièges à sédiments, d’échantillonneurs de ... [more ▼]

Plusieurs techniques existent pour calculer l’épaisseur de la couche active de charriage et le débit solide des rivières. Il peut s’agir de chaînes d’érosion, de pièges à sédiments, d’échantillonneurs de charge de fond de type Helley-smith, de galets marqués, ou encore du dépouillement d’archives de curages (Houbrechts et al., 2012). Ces techniques permettent également de déterminer l’impact de travaux d’aménagements ou de restauration de cours d’eau. Dans le cadre de conventions de recherches financées par la DCENN, deux techniques complémentaires ont été utilisées afin d’analyser le transport de charge de fond de rivières de Wallonie. Tout d’abord des chaînes d’érosion ont été implantées en travers du fond du lit, elles permettent de calculer l’épaisseur et la section de la couche de sédiments mobilisés lors des crues. Les puissances spécifiques des crues analysées varient entre 15 et 195 W/m² et ont généré une épaisseur de couche active comprise entre 9 et 80 mm. Ensuite, la distance parcourue par la charge de fond durant des crues mobilisatrices a été estimée à l’aide de galets marqués par des transpondeurs passifs (PIT-tags). Selon l’importance des crues, les distances moyennes de transport observées sont comprises entre 4 et 297 m. En croisant les données obtenues à l’aide de ces deux techniques, le débit solide de charge de fond a également pu être estimé. A titre d’exemple, le débit solide des rivières varie entre 0,02 t.km-2/crue et 2 t.km-2/crue, lorsque la rupture de la couche d’armurage se produit. [less ▲]

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See detailUtilisation des drones comme outil de suivi de travaux de restauration : génération de séries temporelles d'orthomosaïques à très haute résolution et de modèles numériques de surface
Michez, Adrien ULg; Lisein, Jonathan ULg; Geerts, Cédric ULg et al

Poster (2013, October 15)

D'une invention initialement militaire, les drones - et les applications qui dérivent de leurs utilisation - tendent à se banaliser au sein du domaine civil. En terme d'applications géographiques, les ... [more ▼]

D'une invention initialement militaire, les drones - et les applications qui dérivent de leurs utilisation - tendent à se banaliser au sein du domaine civil. En terme d'applications géographiques, les micro-drones (< 2 kg) occupent un segment nouveau dans les techniques d’acquisition d'informations, à mi-chemin entre deux segments plus classiques, représentés par les techniques d'acquisitions « terrain » (LiDAR terrestre, lever topographique, cartographie GPS, ..) et l'imagerie aérienne (caméra métrique, LiDAR aérien, imagerie satellitale). A l'aide d'un micro-drone X100 (Gatewing-Trimble), l'Unité GRFMN a effectué différents survols du projet de restauration du ruisseau du Morby, entrepris dans le cadre du projet Life+ Walphy. Les survols ont permis la réalisation d'orthomosaïques et de MNS (à l'aide d'Agisoft Photoscan) aux différentes étapes du chantier. Une évaluation de la qualité des MNS photogrammétriques générés est réalisée sur base de données LiDAR aérien disponible sur la zone. Une comparaison des coûts sera également réalisée entre les différentes techniques d'acquisition de données topographiques déployées sur le site lors du projet : MNS photogrammétriques UAV et caméra large format, LiDAR aérien. [less ▲]

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See detailMOLECULAR CHARACTERIZATION OF CLOSTRIDIUM DIFFICILE STRAINS FROM ELDERLY CARE HOME RESIDENTS
Rodriguez Diaz, Cristina ULg

Poster (2013, October 11)

Clostridium difficile is the primary cause of nosocomial diarrhoea and pseudomembranous colitis after use of antibiotics. Production of toxins A and B are the main virulence factors responsible for its ... [more ▼]

Clostridium difficile is the primary cause of nosocomial diarrhoea and pseudomembranous colitis after use of antibiotics. Production of toxins A and B are the main virulence factors responsible for its pathogenicity. Increasing age, several co-morbidities, environmental contamination, antibiotic exposure and other intestinal perturbations appear to be the greatest risk factors for C. difficile infection (CDI). Therefore, elderly care home residents are considered particularly vulnerable to CDI. The aim of this study was to evaluate and follow the prevalence of C. difficile in a Belgian nursing home and to characterize the C. difficile strains isolated from faeces of elderly care home residents. [less ▲]

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See detailGrowth performance and meat quality of stress negative Piétrain pigs in the tropics: the case of Vietnam
Ha Xuan, Bo; Do Duc, Luc ULg; Moula, Nassim ULg et al

Poster (2013, October 11)

This study was carried out at the animal farm of Hanoi University of Agriculture, Vietnam to evaluate the growth performance and meat quality of stress negative Piétrain pigs. The study concerns the body ... [more ▼]

This study was carried out at the animal farm of Hanoi University of Agriculture, Vietnam to evaluate the growth performance and meat quality of stress negative Piétrain pigs. The study concerns the body weight (BW) of 116 pigs at 7.5 months of age and the ultrasound measurements on 83 live animals in order to determine backfat thickness, longissimus muscle depth and lean meat percentage (LM). Meat color (C.I.E L*, a* and b*), peak shear force (SF), pH at 24h (pH24) and at 45 minutes (pH45) post mortem were measured on 31 meat samples. Meat chemical composition (dry matter, protein, lipids and ash) was determined on 23 meat samples. All the data were analyzed according to a linear fixed model including gender effect (female and intact males) and Halothane genotype (CC and CT). The interaction between gender and genotype was not observed and therefore it was ignored from the final model. The results show that BW and LM were not significantly different between genotypes (P>0.21) while females were heavier than males (101.11 vs. 93.85 kg, P=0.0011). LM of female and male were respectively 63.27 and 63.56%. Gender and genotype didn’t affect meat quality and chemical composition (P>0.05) except pH24 (P=0.0011), a* (P<0.0001) and lipids (P=0.0012) for gender effect. The pH45 (6.50 and 6.45 for females and males) and pH24 (5.34 and 5.49 for females and males) were in the range corresponding to a normal meat. The obtained results show that stress negative Piétrain pigs have high lean meat percentage and satisfactory meat quality under tropical climatic conditions in Vietnam. [less ▲]

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See detailEvaluation morphométrique des chevaux pur-sang Arabe en Algérie: mensurations corporelles et proposition d’équations barymétriques
Tennah, Safia ULg; Kafidi, Nacereddine; Antoine-Moussiaux, Nicolas ULg et al

Poster (2013, October 11)

Cette étude vise à la caractérisation morphobiométrique des chevaux de course pur-sang arabe et à l’estimation d’équations barymétriques adaptées à cette race. La caractérisation a concerné 98 chevaux ... [more ▼]

Cette étude vise à la caractérisation morphobiométrique des chevaux de course pur-sang arabe et à l’estimation d’équations barymétriques adaptées à cette race. La caractérisation a concerné 98 chevaux, dont 44 femelles et 54 mâles, tous âgés de trois ans et plus, auprès de 77 propriétaires-éleveurs dans 3 hippodromes d’Algérie (Zemmouri, Tiaret et Caroubier). Dix-neuf mensurations étaient relevées ainsi que le poids vif (PV). Le poids moyen est de 456,2 +/- 43,0 kg, variant de 335 kg à 545 kg. La sélection des variables à inclure dans les équations barymétriques a été réalisée à l’aide de la procédure stepwise du SAS. Quatre mensurations parmi les 19 réalisées ont été retenues pour la proposition d’équations d’estimation du poids vif des chevaux : le périmètre thoracique (PT), la hauteur à la croupe (HC), la longueur de l’encolure (LE) et le tour de l’encolure (TE). Ainsi, les équations proposées pour les mâles et pour les femelles sont respectivement de : PV= 7,024*PT - 787,119 (R²=0,99); PV=6,207*PT + 0,633*HC + 0,668*TE - 0,878*LE - 746,370 (R²=0,96). Les résultats de cette étude devraient permettre aux propriétaires-éleveurs et entraineurs de suivre aisément le poids de leurs chevaux. Ce suivi est nécessaire pour adapter l’activité et l’alimentation des chevaux et favoriser leur performance en course. [less ▲]

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See detailEnvironment factors affecting racing performances of Thoroughbred horses in Algeria
Tennah, Safia ULg; Kafidi, Nacereddine; Antoine-Moussiaux, Nicolas ULg et al

Poster (2013, October 11)

The results of the flat races organized in Algeria from 1995 to 2007 by the Algerian Horse Racing Society were used to estimate non-genetic parameters of racing performances of Thoroughbred horses ... [more ▼]

The results of the flat races organized in Algeria from 1995 to 2007 by the Algerian Horse Racing Society were used to estimate non-genetic parameters of racing performances of Thoroughbred horses. Performances were assessed through two earnings traits (the logarithm of annual virtual earnings: LAEV and the logarithm of average annual virtual earnings per start: LAEV/S) and a normalized ranking (PERF). The phenotypic correlations between these traits were calculated, in order to deduce what is common and what is specific to each measure. The environment factors that were investigated are age (3 to 8 years and older), sex (male or female), year of race (1995 to 2007) and the interactions between these factors. The General Linear Model (GLM) procedure from SAS software was used to identify and quantify the non-genetic factors affecting racing performances. The results showed significantly high positive correlations (p<0.001) between the three traits, hence considered as accounting for similar aptitudes. The effects of age (with a plateau between 4 and 5 years) and year (with an increasing trend for more recent years) turned out to be significant (p<0.001) for the three traits, the sex effect was only significant for the PERF trait (with better performances for males than females) and an interaction between the age and year of the performance was the only significant interaction (p<0.05) for the LAEV trait. The significant effects of these non-genetic factors indicate the need to adjust the earnings and ranks in the context of a program for genetic improvement of Thoroughbred horses in Algeria. [less ▲]

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See detailLongitudinal quality of life assessment in cancer trials: should data be treated as continuous or ordinal?
Donneau, Anne-Françoise ULg; Mauer, Murielle; Coens, Corneel et al

Poster (2013, October 11)

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See detailGenetic parameters of racing performance traits of Arabian horses in Algeria
Tennah, Safia ULg; Kafidi, Nacereddine; Antoine-Moussiaux, Nicolas ULg et al

Poster (2013, October 11)

The data used in the present study were recorded at the Algerian Horse Racing Society for 36492 racing performance of 913 Arabian horses from 1995 to 2007. The aim of the study was to identify the genetic ... [more ▼]

The data used in the present study were recorded at the Algerian Horse Racing Society for 36492 racing performance of 913 Arabian horses from 1995 to 2007. The aim of the study was to identify the genetic parameters underlying three traits: two earnings traits, namely the logarithm of average annual virtual earnings (LAEV) and the logarithm of average annual virtual earnings per start (LAEV/S), and a ranking trait, the normalized ranking (PERF). To identify the fixed effects to be included in the genetic mixed model, a preliminary analysis was conducted using the General Linear Models (GLM) procedure from SAS software. The effects of age, sex, year and the interaction between year of the race and age and between sex and age were included in the model for the three traits. Afterwards, two random effects, a direct genetic effect of the animal and a permanent environmental effect were included in the mixed model. The variance components and genetic parameters were estimated using the restricted maximum likelihood (REML) procedure with the MTDFREML program. The analyses with this repeatable animal model led to the following estimation of the genetic parameters: for LAEV, heritability was 0.225 (±0.041), while estimate of repeatability was 0.330 (±0.040). For LAEV/S, heritability was 0.164 (±0.027), while estimate of repeatability was 0.215 (±0.022). The heritability for the normalized ranking was higher, 0.369 (±0.054), indicating that this trait might provide faster progress for breeding programs of Arabian horses in Algeria. The repeatability estimate for the normalized ranking was 0.587 (±0.045). The genetic correlation between LAEV and LAEV/S was 0.99, revealing a almost complete genetic dependence between these two traits, 0.69 between PERF and LAEV and 0.79 between PERF and LAEV/S. [less ▲]

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See detailCaractérisation de la race ovine Tazegzawth en Algerie: description morpho-biométrique et détermination d’une formule barymétrique
Moula, Nassim ULg; Philippe, François-Xavier ULg; Do Duc, Luc ULg et al

Poster (2013, October 11)

Le mouton Azegzaw est de robe blanche avec des taches noires à reflets bleuâtres sur le chanfrein, le pourtour des yeux et le lobe des oreilles. Non répertoriée par le standard des races ovines ... [more ▼]

Le mouton Azegzaw est de robe blanche avec des taches noires à reflets bleuâtres sur le chanfrein, le pourtour des yeux et le lobe des oreilles. Non répertoriée par le standard des races ovines algériennes, cette race présente pourtant des qualités intéressantes d'adaptation aux régions montagneuses de Kabylie, ce qui justifie la mise en œuvre d’un programme de conservation de ce patrimoine génétique original. L’objectif de cette étude, est (1) de caractériser la morpho-biométrie de moutons de race Tazegzawth et (2) de déterminer des équations barymétriques destinées à l’estimation du poids vif (PV) au départ des mensurations corporelles (périmètre thoracique: PT ; longueur du corps: LDC ; hauteur au garrot : HG ; hauteur à la croupe : HC). Au total, 89 sujets adultes (12 mâles, 77 femelles) sont concernés par cette étude. Les mensurations corporelles moyennes observées sont : - PV: 41,53±0,53 kg (mâle: 46,71kg et femelle: 40,72kg) ; - PT: 73,52±0,45 cm (mâle: 78,37cm et femelle: 72,77cm) ; - LDC: 89,10±0,44 cm (mâle: 93,82cm et femelle: 88,37cm) ; - HG: 71,40±0,43 cm (mâle: 76,06cm et femelle: 70,68cm); - HC: 70,14±0,42 (mâle: 74,80cm cm et femelle: 69,42). Les formules retenues pour l’estimation du PV sont: - Tous sexes confondus : PV=-0,025 HG2 + 4,78HG-169,88 (R2=0,87) - Femelles : PV = -0,038HG2 +6,58HG-232,39 (R2=0,84) - Mâles : PV = -0,16LDC2+0,21 HC2+284,92 (R2=0,99) En dépit de l’échantillon réduit dans l’étude, celui-ci a révélé des caractéristiques relativement homogènes. La détermination d’une formule barymétrique pourra venir en soutien d’une sélection incluant un objectif de croissance. [less ▲]

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See detailPedigree analysis in the Arabian horse in Algeria: estimation of inbreeding coefficient
Tennah, Safia ULg; Kafidi, Nacereddine; Antoine-Moussiaux, Nicolas ULg et al

Poster (2013, October 11)

The studbook of the Arabian horse used in this study is recognized by international authorities such as the WAHO (World Arabian Horse Organization). The pedigree file of the horses includes 1812 animals ... [more ▼]

The studbook of the Arabian horse used in this study is recognized by international authorities such as the WAHO (World Arabian Horse Organization). The pedigree file of the horses includes 1812 animals from 166 stallions (with an average of 10.11 ± 17.33 offspring) and 392 mares (with an average of 4.30 ± 3.76 offspring). The maximal pedigree depth was 18 generations. Inbreeding coefficients of horses present in our data were estimated using the software "Pedigree Viewer" and MTDFREML software on the basis of the provided pedigree. The estimation of the inbreeding coefficient for the 1812 horses showed that 1177 animals from all those present in the pedigree were consanguineous, with an inbreeding coefficients varying from 0,00002 to 0,265, with an overall mean of 0,0275 ± 0,001. The average value of the inbreeding coefficient in the population of Arabian horses in Algeria is thus relatively high. It is to be noticed that this average coefficient of inbreeding is less than the threshold established as problematic in the inbreeding literature (6%); however, 13.5% of the total population shows inbreeding coefficients above this threshold. It is therefore important to educate owners-breeders to the problems that consanguinity can generate, and to avoid as much as possible practices that increase inbreeding, such as a too intensive use of a major ancestor, the use of a too small number of breeding animals and the use of crosses between related individuals. All these measures are necessary to prevent rapid inbreeding increase, which would result in a significant loss of genetic diversity, with a medium-term potentially negative effect on racing performances and reproduction. [less ▲]

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See detailEvaluation of some production parameters in Kabyle local rabbit population
Moula, Nassim ULg; Michaux, Charles ULg; Do Duc, Luc ULg et al

Poster (2013, October 11)

In Algeria, the rabbit production is mainly based on local population to ensure a cheap supply of urban markets proteins. This sector may represent an important source of protein which is in large deficit ... [more ▼]

In Algeria, the rabbit production is mainly based on local population to ensure a cheap supply of urban markets proteins. This sector may represent an important source of protein which is in large deficit in the country. The rabbit production can be justified by its advantages such as short life cycle and high prolificacy. The objective of the present study is to evaluate production performances of Kabyle local rabbit population. Litter size, growth rate, body slaughter weight, feed conversion ratio and mortality rate are considered. The experiment was carried out on 30 animals (6 males and 24 females) for reproduction in the Ath Waghlis region (north-east Algeria). Rabbits have been raised in pens with 1 male and 4 females per pen. The commercial feed was supplied ad libitum to animals. Results reported shown that total number of rabbits born, number born alive, number to weaned, slaughter weight at 84 days of age, feed conversion ratio (from weaning to slaughter) and survival rate (from birth to slaughter) were 7.1, 6.1, 5.3 rabbits, 1.90kg, 3.16 and 73% respectively. The performances of the Kabyle breed could be improved by purebred selection as well as by crossing with exotic breeds. [less ▲]

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See detailVitrification of immature equine oocytes
Gatez, Carine ULg; Ectors, Fabien ULg; Farnir, Frédéric ULg et al

Poster (2013, October 11)

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See detailBacterial diversity and its evolution during storage of fresh beef from different origins under different atmosphere and temperature conditions
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Taminiau, Bernard ULg et al

Poster (2013, October 11)

The purpose of this study was to evaluate the bacterial diversity and its evolution during storage of fresh beef, depending on its origin, packaging and storage temperature. Two batches of three vacuum ... [more ▼]

The purpose of this study was to evaluate the bacterial diversity and its evolution during storage of fresh beef, depending on its origin, packaging and storage temperature. Two batches of three vacuum packed striploins from United Kingdom and Belgium were obtained from a food wholesaler located in the Walloon Region. Fifteen days after slaughter, the striploins were sliced and individually kept under vacuum for 30 days: i) at −1 °C; ii) at +4 °C and iii) at −1 °C for 15 days and then at +4 °C for 15 days. The bacterial diversity was evaluated by metagenomic approach 15, 30 and 45 days after slaughter. Furthermore, each 15 days part of the vacuum packed striploin slices were repacked under modified atmosphere (70 % O2/30 % CO2), stored at +4 °C for 2 days and at +8 °C for 5 days, and then analyzed. Metagenomic analysis revealed a selection of the initial flora depending on atmosphere and temperature conditions. The development of Lactobacillus algidus was favored in samples preserved under vacuum at −1 °C, while a predominance of Lactococcus piscium was observed for samples stored at +4 °C. Moreover, storage under modified atmosphere favored the development of Leuconostoc gasicomitatum. These microorganisms have already been isolated from beef, but no study has evaluated their role in food conservation. The next step of this study will be to isolate and characterize strains of Lactobacillus algidus from meat and to assess their bioprotective potential. [less ▲]

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See detailEncapsulation de micro-algues dans un matériaux hybride alginate-silice et production de molécules à hautes valeur ajoutée
Duprez, Marie-Eve; Mirisola, A.; Rooke, Joanna et al

Poster (2013, October 10)

Les micro-algues sont des micro-organismes photosynthétiques. Leur croissance en milieu aqueux nécessite un apport lumineux (l = 400 à 700 nm) ainsi qu’un apport en carbone et en nutriments (N, P, S, etc ... [more ▼]

Les micro-algues sont des micro-organismes photosynthétiques. Leur croissance en milieu aqueux nécessite un apport lumineux (l = 400 à 700 nm) ainsi qu’un apport en carbone et en nutriments (N, P, S, etc.). Certaines souches, Dunaliella sp. par exemple, sont couramment utilisées dans le cadre de la biosynthèse de caroténoïdes[1] (b-carotène, lutéine entre autres). Quelques recherches ont montré qu’il était possible de réaliser l’extraction in situ des métabolites produits dans un réacteur biphasique (le b-carotène hydrophobe est extrait dans une phase organique biocompatible telle que le décane ou le dodécane) [2,3,4,5]. Le projet FOTOBIOMAT (subsidié par le programme Greenomat de la Région Wallonne – Belgique) a pour but de développer un nouveau type de photobioréacteur dans lequel sont mises en oeuvre les micro-algues encapsulées dans des billes constituées d’un matériau hybride. Le processus de photosynthèse est ainsi utilisé afin de convertir du CO2 en composés à haute valeur ajoutée (b-carotène p. ex.). La viabilité des micro-algues encapsulées doit être très importante (min. 6 mois). Idéalement, le b-carotène produit devrait être récupéré par une voie “propre” et ce, quasi en continu. [less ▲]

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See detailEncapsulation de micro-algues dans un matériaux hybride alginate-silice et production de molécules à hautes valeur ajoutée
Duprez, Marie-Eve; Mirisola, A; Desmet, Jonathan et al

Poster (2013, October 10)

Les micro-algues sont des micro-organismes photosynthétiques. Leur croissance en milieu aqueux nécessite un apport lumineux (l = 400 à 700 nm) ainsi qu’un apport en carbone et en nutriments (N, P, S, etc ... [more ▼]

Les micro-algues sont des micro-organismes photosynthétiques. Leur croissance en milieu aqueux nécessite un apport lumineux (l = 400 à 700 nm) ainsi qu’un apport en carbone et en nutriments (N, P, S, etc.). Certaines souches, Dunaliella sp. par exemple, sont couramment utilisées dans le cadre de la biosynthèse de caroténoïdes[1] (b-carotène, lutéine entre autres). Quelques recherches ont montré qu’il était possible de réaliser l’extraction in situ des métabolites produits dans un réacteur biphasique (le b-carotène hydrophobe est extrait dans une phase organique biocompatible telle que le décane ou le dodécane) [2,3,4,5]. Le projet FOTOBIOMAT (subsidié par le programme Greenomat de la Région Wallonne – Belgique) a pour but de développer un nouveau type de photobioréacteur dans lequel sont mises en oeuvre les micro-algues encapsulées dans des billes constituées d’un matériau hybride. Le processus de photosynthèse est ainsi utilisé afin de convertir du CO2 en composés à haute valeur ajoutée (b-carotène p. ex.). La viabilité des micro-algues encapsulées doit être très importante (min. 6 mois). Idéalement, le b-carotène produit devrait être récupéré par une voie “propre” et ce, quasi en continu. [less ▲]

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Peer Reviewed
See detailUse of on-line flow cytometry to detect segregation in the microbial population
Brognaux, Alison ULg; Zune, Quentin ULg; Han, Shanshan et al

Poster (2013, October 08)

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See detailInterpolation of SLA Using the Data-Interpolating Variational Analysis in the Coastal Area of the NW Mediterranean Sea
Troupin, Charles ULg; Barth, Alexander ULg; Beckers, Jean-Marie ULg et al

Poster (2013, October 07)

The spatial interpolation of along-track Sea-Level Anomalies (SLA) data to produce gridded map has numerous applications in oceanography (model validation, data assimilation, eddy tracking, ...). Optimal ... [more ▼]

The spatial interpolation of along-track Sea-Level Anomalies (SLA) data to produce gridded map has numerous applications in oceanography (model validation, data assimilation, eddy tracking, ...). Optimal Interpolation (OI) is often the preferred method for this task, as it leads to the lowest expected error and provides an error field associated to the analyzed field. However, the method suffers from limitations such as the numerical cost (due to the inversion of covariance matrices) as well as the isotropic covariance function, generally employed in altimetry. The Data-Interpolating Variational Analysis (DIVA) is a gridding method based on the minimization of a cost function using a finite-element technique. The cost function penalizes the departures from observations, the smoothness of the gridded field and physical constraints (advection, diffusion, ...). It has been shown that DIVA and OI are equivalent (provided some assumptions on the covariances are made), the main difference is that in DIVA, the covariance function is not explicitly formulated. The technique has been previously applied for the creation of regional hydrographic climatologies, which required the processing of a large number of data points. In this work we present the application and adaptation of Diva to the analysis of SLA in the Mediterranean Sea and the production of weekly maps of SLA in this region. The peculiarities of SLA along-track data are addressed: • number of observations: the finite-element technique coupled to improvements in the matrix inversion (parallel or iterative solvers) lead to a decrease of the computational time, meaning that sub-sampling of the initial data set is not required. • quality of the different missions: the weight attributed to each data point can be easily set according to the satellite that provided the observations, so that different measurement noise variances are considered. • spatial correlation scale: it varies spatially in the domain according to the value of the Rossby radius of deformation. • long-wavelength errors: each data point is associated a class, and a detrending technique allows the determination of the trend for each class, leading to a reduction of the inconsistencies between missions. • anisotropy of physical coastal features: a pseudo-velocity field derived from regional bathymetry enhances the correlations along the main currents. Particular attention will be paid to the influence of this constraint in the coastal area. The analysis and error fields obtained over the Mediterranean Sea are compared with the available gridded products from AVISO. Different ways to compute the error field are compared. The impact of the use of multiple missions to prepare the gridded fields is also examined. In situ measurements from an intensive multi-sensor experiment carried out north of the Balearic Islands in May 2009 serve to assess the quality of the gridded fields in the coastal area. [less ▲]

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See detailInsertion of domain III of Bacillus subtilis and Bacillus amyloliquefaciens PBP4a in the Bacillus licheniformis BlaP β-lactamase to study the binding to peptidoglycan and whole bacteria
Van Der Heiden, Edwige ULg; Hoebreck, Charline ULg; Freichels, Régine ULg et al

Poster (2013, October 03)

Domain III of Bacillus subtilis and B. amyloliquefaciens DD-endopeptidase PBP4a was introduced in the BlaP beta-lactamse of Bacillus licheniformis. Domain III of Bacillus licheniformis binds to ... [more ▼]

Domain III of Bacillus subtilis and B. amyloliquefaciens DD-endopeptidase PBP4a was introduced in the BlaP beta-lactamse of Bacillus licheniformis. Domain III of Bacillus licheniformis binds to peptidoglycan of Bacillus subtilis 168 and to itself whole cells. [less ▲]

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See detailBacterial diversity of field-caught mosquitoes from different regions of Belgium and potential impact on virus transmission
Raharimalala, Fara Nantenaina ULg; Boukraa, Slimane ULg; Bawin, Thomas ULg et al

Poster (2013, October 02)

Several vectors disease presented a resistance to various pesticides currently used. Endosymbiotic bacteria was an alternative solution found because of their probably interactive effects with their host ... [more ▼]

Several vectors disease presented a resistance to various pesticides currently used. Endosymbiotic bacteria was an alternative solution found because of their probably interactive effects with their host. According to the introduction risks of these virus and disease dispersion, we propose to investigate the bacterial endosymbiont role in Culicidae in Belgium. Among the 30 species of mosquitoes identified in this country, about ten are considered as potential vectors of arboviruses. In this study, eleven species of Culicidae belonging to five genera (Culex pipiens s.l., Cx. torrentium, Cx. hortensis, Anopheles claviger, An. maculipennis s.l., An. plumbeus, Culiseta annulata, Ochlerotatus geniculatus, Oc. dorsalis, Aedes albopictus and Coquillettidia richiardii) mosquitoes fields from eight sites of Belgium were used for the screening of the presence of six genera endosymbiotic bacteria (Wolbachia sp, Commamonas sp, Delftia sp, Pseudomonas sp, Acinetobacter sp and Asaia sp) according their possible impact in mosquito biology. PCR was done for the screening of endosymbiotic bacteria mosquitoes studied. A total of 176 individuals (144 larvae and 32 adults) were used. Our results allowed us to confirm the absence of Wolbachia in An. clavigere, An. maculipennis s.l and Cx. torentium. Acinetobacter was found in every species. Current advances in understanding the mosquito–microbiota relationships may have a great impact in a better understanding of some traits of mosquito biology and in the development of innovative mosquito-borne disease-control strategies aimed to reduce mosquito vectorial capacity and/or inhibiting pathogen transmission. [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 ▲]

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See detailANAEROBIC DIGESTION OF ORGANIC WASTES FROM AGRO-FOOD ACTIVITIES IN TUNISIA
Mhiri, F; Hiligsmann, Serge ULg; Sayahi, L. et al

Poster (2013, October 01)

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See detailImpact of anti-androgenic substances on gametogenesis of the rotifer Brachionus calyciflorus
Cruciani, Valentina ULg; Thomé, Jean-Pierre ULg; Joaquim-Justo, Célia ULg

Poster (2013, October 01)

Several studies have shown that pollutants with anti-androgenic activity have an impact on the sexual reproduction of the rotifer Brachionus calyciflorus (Joaquim-Justo et al., submit; Preston et al ... [more ▼]

Several studies have shown that pollutants with anti-androgenic activity have an impact on the sexual reproduction of the rotifer Brachionus calyciflorus (Joaquim-Justo et al., submit; Preston et al., 2001). The effects observed are compatible with the phenomenon of endocrine disruption. Fenitrothion, a non-steroidal anti-androgen induces a decrease in fertilization rate following exposure below or equal to 0,5 mg L-1.. The steroidal anti-androgen, cyproterone acetate increases number of cysts in population exposed to concentrations below or equal to 0,5 mg L-1. Cross mating experiments showed that effects of fenitrothion are due to an impact on males exclusively, while effects of cyproterone acetate exposition are due to an impact on females exclusively. In this study, we investigated the impact of fenitrothion on spermatogenesis and observed a decrease in the spermatozoa production and mobility with concentrations down to 0,5 mg L-1. We report a detailed description of the morphology of the male reproductive apparatus in B. calyciflorus based on optic, transmission electron and scanning electron microscopy in controls and exposed individuals. [less ▲]

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See detailStudy of the virulence of serotypes 4 and 9 of African horse sickness virus in two mouse models
De la Grandière de Noronha Cotta, Maria Ana ULg; Zonta, William ULg; Mauroy, Axel ULg et al

Poster (2013, October)

African horse sickness (AHSV) is an infectious disease caused by a double stranded positive RNA virus which belongs to the family Reoviridae, genus Orbivirus. The virus has nine serotypes and is ... [more ▼]

African horse sickness (AHSV) is an infectious disease caused by a double stranded positive RNA virus which belongs to the family Reoviridae, genus Orbivirus. The virus has nine serotypes and is transmitted by a culicoides biting midge, principally Culicoides imicola. African horse sickness causes severe morbidity and mortality up to 95 % in horses with severe economic losses. The establishment of an experimental model is needed for the investigation of the pathogenesis of this infection. Two mouse models, interferon-α receptor knock-out mice (A129 KO or IFNAR -/-) and immunocompetent mice (A129 WT), were tested. The viruses used for mice inoculations belonged to the two serotypes which caused epidemics in Europe, serotypes 4 and 9. The virus was inoculated by subcutaneous (SC) route and/or by intra-nasal (IN) route. Whole blood samples were taken from each mouse at regular intervals. The organs (liver, spleen, kidney, lung and brain) were taken at the end of the experiment or when the most affected mice were euthanized. All these samples were tested by a qRT-PCR targeting AHSV genome segment 7. Both serotypes of AHSV were detected by qRT-PCR until three weeks post-infection in blood of IFNAR -/- mice and A129 WT mice infected by SC route. Serotype 4 shows a higher peak of viremia than serotype 9. The peak of viremia was measured between day 2 and day 4 post-infection. These results demonstrate the potential of the immunodeficient mouse model for both clinical and biological features. The setting up of this mouse model has developed a tool for efficient in vivo study to characterize the in vivo virulence of this virus, to monitor the evolution of viral populations during in vivo replication cycles and to test the competence or vectorial capacity of indigenous Culicoides. Research supported by the Belgium Federal Public Service, Health, Food Chain Safety and Environment. [less ▲]

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See detailHerschel observations of nebulae ejected by massive evolved stars
Vamvatira-Nakou, Chloi ULg; Hutsemekers, Damien ULg; Royer, P. et al

Poster (2013, October)

We have obtained far-infrared Herschel PACS imaging and spectroscopic observations of nebulae associated to massive evolved stars. The study of these nebulae is crucial to understand the evolution of ... [more ▼]

We have obtained far-infrared Herschel PACS imaging and spectroscopic observations of nebulae associated to massive evolved stars. The study of these nebulae is crucial to understand the evolution of these stars as it can reveal the mass-loss history. The infrared images along with available data at other wavelengths give a complete view of their morphology. The dust modeling provides the dust parameters, such as the temperature, the mass and the composition of dust. The spectroscopic analysis provides the gas C,N,O abundances and mass. Based on these observations, the evolutionary status of the star at the time of the nebula ejection can be constrained. We present here selected results of an ongoing exhaustive study of nebulae around low- and high-luminosity LBVs (AG Car, HR Car, WRAY 15-751, G79.29+0.46, HD168625), WN stars (NGC6888, M1-67, He3-519) and Of stars (NGC6164/5). [less ▲]

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See detailFirst Evidence of a Volatile Sex Pheromone in Harmonia axyridis (Pallas)
Fassotte, Bérénice ULg; Fischer, Christophe ULg; Durieux, Delphine ULg et al

Poster (2013, October)

Until now, no volatile sex pheromone has been highlighted in Coccinellidae but various studies have suggested the existence of such molecules. In the present work, we have sampled volatile organic ... [more ▼]

Until now, no volatile sex pheromone has been highlighted in Coccinellidae but various studies have suggested the existence of such molecules. In the present work, we have sampled volatile organic compounds released in the headspace of virgin females in the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), that were either allowed or not to feed on pea aphids (Acyrthosiphon pisum Harris). When fed on aphids, virgin females showed a stereotypical “calling behavior”, commonly associated with the emission of a sex pheromone in several Coleoptera species. Behavioral assays conducted with calling females in a four-arm olfactometer demonstrated that the blend of released volatile compounds was attractive at a distance for males, but not for other females. The headspace of virgin females that were not previously fed with aphids was not attractive for either sex. GC-MS analyses revealed the presence of five compounds in the volatile blend: (–)-β-caryophyllene, β-elemene, methyl-eugenol, α-humulene and α-bulnesene. Subsequently, we have collected and quantified the constituents from the blend over a period of 9 days after exposure to aphids. All five compounds were produced exclusively after feeding virgin females with aphids, and their quantity significantly increased during the whole period of collection. (–)-β-caryophyllene was found to be the major constituent, representing between 80 and 86 % of the total blend. All these results could promote the development of more specific and efficient management methods to manipulate the movements of this invasive ladybeetle and to reduce its negative impacts on biodiversity. [less ▲]

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See detailImpact of sludge storage duration on its dewatering and drying ability
Pambou, Yvon-Bert; Salmon, Thierry ULg; Fraikin, Laurent ULg et al

Poster (2013, October)

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See detailImaging mass spectrometry and proteomics of 3D cell cultures
Longuespée, Rémi ULg; Piron, Céline; Fléron, Maximilien et al

Poster (2013, October)

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See detailMartian thermospheric temperatures retrieved from SPICAM dayglow measurements
Stiepen, Arnaud ULg; Gérard, Jean-Claude ULg; Montmessin, Franck et al

Poster (2013, October)

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See detailECONOMIC IMPACT OF USING AN ANTIVIRAL IN THE CONTROL OF A FOOT-AND-MOUTH DISEASE EPIZOOTIC IN SOUTHERN BELGIUM
Dal Pozzo, Fabiana ULg; Humblet, Marie-France ULg; Vandeputte, Sébastien ULg et al

Poster (2013, October)

Foot-and-mouth disease virus (FMDV) is a highly contagious pathogen of cloven-hoofed mammals and one of the biggest concerns for veterinary authorities. The control measures to be applied in case of an ... [more ▼]

Foot-and-mouth disease virus (FMDV) is a highly contagious pathogen of cloven-hoofed mammals and one of the biggest concerns for veterinary authorities. The control measures to be applied in case of an outbreak vary in function of the disease-free or disease-enzootic status. Vaccination depends on the prior identification of the involved viral serotype and subtype, it confers an immunity limited to 6 months and it requires between 4 to 7 days to trigger the immune response (i.e. immunity-gap). The use of anti-FMD drugs has been discussed as an alternative or supplementary method to be used in previously FMD-free countries/zones. Such an antiviral treatment could protect against the viral dissemination to fill the gap between vaccination and the rise of a protective immunity. Apart from broad spectrum antiviral agents, such as ribavirin, specific anti-FMDV molecules have been identified in vitro, but none of them has been used in clinical studies involving ruminants or pigs. Next to the anti-FMDV activity, the absence of toxicity and the withdrawal period influencing the food safety, the cost of the treatment would be another important parameter influencing the potential use of an antiviral agent in the control of a FMD outbreak. The aim of this study was to assess the economic impact of using an antiviral in the control of a FMD epizootic in southern Belgium (Walloon Region). This work was based on the results of previous investigations concerning the epidemiological and economic data of a FMD outbreak in Southern Belgium. In the considered scenario, the epizootic was caused by the introduction of an infected cow (during the incubation time) in a beef cattle farm during winter. During the two weeks between the brood cow introduction and the official declaration of the outbreak, animal movements occurred between other beef cattle farms. The economic effects of the epidemic were evaluated taking into account the air-borne transmission of FMDV, the occurrence of animal movements (two scenarios were considered, with a minimum of 2 and a maximum of 17 movements), the presence of bovine and small ruminant farms, as well as pig farms in the protection and surveillance zones around the initial and secondary outbreaks. The wild fauna was not involved in the epidemic. In order to integrate in the above scenario the application of an antiviral agent in the control of the disease, it was assumed that the efficacy of the anti-FMDV drug was proven by reducing viral excretion in infected animals as well as by preventing the infection in animals at risk. Two hypothetical prices were used to introduce in the model the costs related to the administration of the antiviral drug (5€ and 10€ per dose). Furthermore, different strategies of control could be envisaged, such as the administration of the drug to both domestic ruminants and pigs, or depending on the epidemiological role of these species in the FMD transmission and their density in the territory, the administration of the drug to only one of them. Other scenarios could be characterized by the use of the antiviral in the control of the epizootic within the protection and surveillance zones or in only one of them. The costs associated with the use of antivirals in the different proposed scenarios are compared to the costs and socio-economic losses associated with the FMD outbreak and the implementation of control measures. [less ▲]

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See detailYellow Hypergiant /Luminous Blue Variable
Cox, N. L. J.; Hutsemekers, Damien ULg; Vamvatira-Nakou, Chloi ULg

Poster (2013, October)

Hen3-1379 is a yellow hypergiant (YHG) with evidence for episodic non-quiescent mass-loss over in last 400-1000 years in this post-red supergiant (RSG) phase of its evolution. The observational evidence ... [more ▼]

Hen3-1379 is a yellow hypergiant (YHG) with evidence for episodic non-quiescent mass-loss over in last 400-1000 years in this post-red supergiant (RSG) phase of its evolution. The observational evidence suggests that though similar to the low-luminosity LBV Wray15-751, it has not yet moved to the hotter phase and is thus pre-LBV. This confirms the scenario of significant mass-loss during the RSG phase. [less ▲]

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See detailLong term culture and characterization of chicken primordial germ cells
Tonus, Céline ULg; Cloquette, Karine; Ectors, Fabien ULg et al

Poster (2013, October)

Avian primordial germ cells (PGCs) can keep their germ cells properties and are foreseen as promising tools for developing avian transgenesis and preservation of genetic resources of endangered species ... [more ▼]

Avian primordial germ cells (PGCs) can keep their germ cells properties and are foreseen as promising tools for developing avian transgenesis and preservation of genetic resources of endangered species. We have developed original methods that allow long term (20 month) expansion of primary cultures of undifferentiated PGCs and their efficient cryopreservation. Blood samples were collected from stage 13-18 embryos, pooled, deposited in cell culture inserts and co-cultivated in the presence of irradiated BRL cells. This physically separated co-culture system along with selective culture medium promoted emergence, selection and proliferation of undifferentiated PGCs lines. Overall, 35% of blood samples gave rise to PGCs cell lines originating from three commercial layer breeds and two Belgian endangered breeds. Moreover, we recently isolate and cultivate a new PGC line from turkey. All PGCs lines were first characterised for the expression of the stem cells and PGCs characteristic marker SSEA-1 by FACS. RT-PCR confirmed expression of germ-line specific markers (CVH, CDH, DAZL), pluripotency markers (cPouV, cSox2, cNanog), telomerase and CXCR4 receptor. In addition, by means of a quantitative PCR amplification of a chromosome W specific sequence, we demonstrated a progressive drift of all our lines towards the male sex (WL), while they were initially isolated from pooled blood samples with statistically equivalent numbers of male and female embryos (35 females: 29 males). PGCs were subsequently efficiently cryopreserved by slow freezing or by a newly developed vitrification method. Labelled PGCs from 10 lines were injected in recipient embryos. At day 6, colonization of the genital ridges confirmed that PGCs retain their gonadal migratory ability, both after long-term culture (min 3, max 20 month) and after cryopreservation. In order to evaluate the germinal differentiation of cultured PGCs during the gonadal development as well as the germline transmission rate, we established a stably expressing GFP line that was successfully injected in emrbyos. Results are in progress. [less ▲]

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See detailA basal thunnosaurian from Iraq reveals disparate phylogenetic origins for Cretaceous ichthyosaurs
Naish, Darren; Fischer, Valentin ULg; Liston, Jeff et al

Poster (2013, October)

A new thunnosaurian from the Kurdistan region of Iraq represents the first post-Triassic ichthyosaur from the Middle East. The specimen is an articulated partial skeleton that includes a partial skull ... [more ▼]

A new thunnosaurian from the Kurdistan region of Iraq represents the first post-Triassic ichthyosaur from the Middle East. The specimen is an articulated partial skeleton that includes a partial skull, complete left forefin, partial ribcage and anterior section of the vertebral column. Associated palynomorphs uncontroversially date the specimen (preserved on a loose slab of matrix) to the late Hauterivian- Barremian interval of the Early Cretaceous. A posterior projection on the humerus, short and trapezoidal humerus, enlarged intermedium, and trapezoidal cervical and anterior dorsal neural spines represent autapomorphies. Forefin morphology is archaic: the carpals, metacarpals and phalanges form a mosaic similar to that of Triassic-Early Jurassic parvipelvians, accessory digits are absent, and notching is present on the leading edge of the first digit. These and other characters indicate exclusion of the Iraq ichthyosaur from Ophthalmosauridae, the only ichthyosaur clade currently known from the Cretaceous. A phylogenetic analysis of Parvipelvia – the largest yet produced – recovers the new taxon as the sister- taxon of Ichthyosaurus communis, thereby invoking a ghost-lineage of over 60 million years. Inclusion of the new taxon in analyses produced by other authors also resulted in exclusion from Ophthalmosauridae, though relationships with other neoichthyosaurians are less resolved than in our analysis. We conclude that the new taxon represents a highly conservative relict – a member of the Ichthyosaurus lineage – that retained an ‘Early Jurassic’ grade of pectoral anatomy into the Cretaceous. Ophthalmosauridae and members of the Ichthyosaurus lineage therefore both persisted beyond the Jurassic. Clearly, both have highly contrasting evolutionary histories and Cretaceous ichthyosaurs do not all represent members of the same evolutionary radiation. The Iraq ichthyosaur is one of several new taxa originally worked on by the late Robert M. Appleby. An inability to resolve conflicting views on the age of the specimen, combined with other issues, derailed his plans to publish on this specimen during the 1970s. [less ▲]

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See detailCompetitive interaction of a synthetic polycation (PDMAEMA) to human platelets and erythrocytes
Flebus, Luca ULg; Lombart, François ULg; martinez, Lucia et al

Poster (2013, October)

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See detailImpact of growth rate on the distribution of visually strength-graded West-European Douglas-fir boards
Henin, Jean-Marc; Hebert, Jacques ULg; Jourez, Benoît ULg

Poster (2013, October)

Douglas-fir is a relatively new species within the forest landscape of Wallonia (Southern Belgium). Consequently, some uncertainties remain regarding how to keep full advantage of its high productivity as ... [more ▼]

Douglas-fir is a relatively new species within the forest landscape of Wallonia (Southern Belgium). Consequently, some uncertainties remain regarding how to keep full advantage of its high productivity as well as of the good properties of its wood. Moreover, the recent implementation of the timber strength grading (Council Directive 89/106/EEC) is likely to sensitize forest managers and the sawing industry to the impact of sylviculture on the resource quality. In that context, this research aimed at assessing to what extent the ring width of the trees (RWtree) and the mean girth increment of the stands (MGI) influences, in the frame of a visual strength grading, the distribution of the boards they produce. The experimental material was derived from 33 trees (girth range of between 120cm and 170cm) originating from 11 Douglas-fir stands (age range of between 41 and 69 y.o.) representative of contrasting sylvicultural management practices: RWtree ranged from 3 to 6 mm. From a bolt located 6 to 8.2m height in the standing trees, boards (38X100X2100mm³) were sawn and graded according to the Belgian Standard NBN B 16-520. This research evidenced that: - Only the Knot Area Ratio (KAR) impedes boards to be employed in structural uses. Practically, no board having a KAR allowing S10 grading (S10 corresponds to C30 as defined in EN338) exhibits a ring width higher than 6mm, which is the maximum value accepted for S10 grading (according to NBN B 16-520). These observations demonstrate the highly prevailing character of the knottiness regarding the boards’ grading; - 87% of the boards produced by trees from RWtree≥5mm can be used in structural uses, but only 7% can be classified into S10 strength class. In comparison, trees with RWtree<4.5mm also provided 87% of boards which can be used in structure, but 18% of the boards can be graded into S10 strength class; - 89% of the boards produced by stands with MGI>3cm/year are accepted for structural uses, but only 9% are graded into S10 class. Regarding the stands with MGI≤3cm/year, these values are 89% and 24%, respectively. Growth rate thus doesn’t seem to affect the percentage of Douglas-fir boards fit for structural uses. Dynamic sylviculture however significantly decreases the percentage of boards graded into S10 strength class: although it should be supported by financial assessments, early pruning thus seems highly advisable in a context of dynamic sylviculture. [less ▲]

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See detailImplementing river restoration taking into account constraints of water supply protection: the case study of the Bocq River at Spontin
Peeters, Alexandre ULg; De le Court, Bernard; Verniers, Gisèle et al

Poster (2013, October)

In the Bocq basin, eastern tributary of the Meuse, restoration works consist of making 20 obstacles passable to improve the free movement of fish and sediment. This presentation focuses on a particular ... [more ▼]

In the Bocq basin, eastern tributary of the Meuse, restoration works consist of making 20 obstacles passable to improve the free movement of fish and sediment. This presentation focuses on a particular case study involving river restoration in a groundwater abstraction zone. In the sixties, a reach of more than 600 meters of the Bocq was completely channelized in order to avoid any risk of contamination of the nearby important drinking water well field area. Ecological quality was consequently impoverished due to the loss of natural habitats (streambed and banks made of concrete and masonry). In addition, the hydraulic conditions (high flow, low depth) make it totally insurmountable for fish. The restoration project started with a 3-year period of consultation with the water abstraction owner to finally reach an agreement on a restoration project taking into account the need of protection of the water abstraction. The project consisted on building rock weirs at regular interval in order to create a succession of 23 steps and pools. Furthermore, various habitats schemes were implemented such as fish shelter, rock berms for aquatic vegetation, and spawning gravel introduction. In addition a small dike and an expansion area for flooding have been completed to protect the water abstraction. This project is being monitored on the basis of geomorphological and ecological analysis. Geomorphological monitoring focuses on the bedload transport with an analysis of flood and the clogging of the gravel layer. Ecological monitoring is based on two indicators (macroinvertebrates and fishes) as well as the analysis of microhabitats. The first results show an improvement after 1 year. [less ▲]

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See detailBehavioural study of  chemical  products during vacuum agitated contact drying
Bennamoun, Lyes; Léonard, Angélique ULg

Poster (2013, October)

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See detailCaractérisation d’un état de référence de l’Eau Blanche pour guider les travaux de restauration écologique
Peeters, Alexandre ULg; Hallot, Eric ULg; Van Campenhout, Jean ULg et al

Poster (2013, October)

Sur l’ensemble de son parcours de 14,5 km à travers la Fagne, l’Eau Blanche a subi d’importants travaux de rectification et de recalibrage, principalement dans les années soixante lors de travaux ... [more ▼]

Sur l’ensemble de son parcours de 14,5 km à travers la Fagne, l’Eau Blanche a subi d’importants travaux de rectification et de recalibrage, principalement dans les années soixante lors de travaux d’assainissement agricole. Ces travaux ont eu pour conséquence de banaliser les habitats aquatiques et rivulaires, entrainant des répercussions sur la faune et la flore aquatique. Dans le cadre du projet Walphy, des travaux de restauration de la continuité transversale ont été réalisés entre 2010 et 2011 sur plus de 6 km de linéaire (comprenant l’Eau Blanche et son affluent, le Grand Morby). Avant ces travaux de restauration et de manière à définir l’état de référence à atteindre, une étude des caractéristiques de l’Eau Blanche avant sa rectification a été entreprise. Ainsi, plusieurs données cartographiques ont pu être rassemblées et analysées, telles que des cartes anciennes et des plans terriers accompagnés de profils transversaux et longitudinaux, ainsi qu’un modèle numérique de terrain à haute résolution MNT-LIDAR. Nous avons dés lors pu comparer le tracé de l’Eau Blanche avant et après sa rectification. Par ailleurs, afin de caractériser l’état de référence visé par les travaux de restauration, les données cartographiques et topographiques anciennes ont été utilisées pour calculer les caractéristiques morphométriques du cours d’eau avant la rectification : pente, indice de sinuosité, longueur d’onde, amplitude et rayon de courbure des méandres, largeur à plein bord, rapport largeur/profondeur... [less ▲]

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See detailDRAMATIC OSTEONECROSIS OF THE JAW ASSOCIATED WITH ORAL BIPHOSPHONATES TREATMENT AFTER IMPLANT REMOVAL: A CASE REPORT
FERNANDEZ AYORA, Alberto ULg; HERION, Francine ULg; LAMBERT, France ULg et al

Poster (2013, October)

BACKGROUND Osteoporosis affects millions of elderly patients. Bisphosphonates represent first-line therapy. Osteonecrosis of the jaws in patients treated with bisphosphonates is mostly associated with ... [more ▼]

BACKGROUND Osteoporosis affects millions of elderly patients. Bisphosphonates represent first-line therapy. Osteonecrosis of the jaws in patients treated with bisphosphonates is mostly associated with intravenous bisphosphonates while the incidence associated with oral bisphosphonates is not significant. AIM This report documents a case of bisphosphonate-related osteonecrosis of the jaw (BRONJ) after dental implant removal in an osteoporotic patient treated with alendronate and risedronate for 15 years. MATERIAL AND METHODS An 83-years-old patient with no significant systemic disease underwent implant removal in the first molar left hemimandible position in 2010 due to a peri-implantitis. The surgical procedure was uneventful thought preventive measures were no taken. In June 2011, the patient was referred to our department with a wide bone sequestration of the left mandibular body. A panoramic radiograph showed an increased bone marrow density with bone sequestration. Since then, the patient underwent several courses of antibiotics and conservative therapy, without relief of symptoms. RESULTS Since 2011, the patient has lost 13 teeth in the mandible and the osteonecrosis has disseminated to the entire jaw and the left mandible condyle. The patient has even lost the left hearing. Resective surgery under general anesthesia is not indicated due to the risk because of the age of the patient. CONCLUSION AND CLINICAL IMPLICATIONS Despite the low risk of BRONJ occurrence after implant surgery in oral N-BP users, the fate of dental implants in these patients remains uncertain. Therefore patients at risk must be given a full explanation of the potential risks of implant failure and BRONJ development. Osteonecrosis of the jaws in association with bisphosphonate therapy is a very serious condition with which all dentists should be familiar. Since the treatment of BRONJ is difficult, prevention is the main goal. When the osteonecrosis begins, it can be very painful to the patient, difficult to treat, and can lead to very deleterious sequelae. [less ▲]

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See detailAstrospheres of young and old stars
Cox, N.; Decin, L.; Marle, A.J. et al

Poster (2013, October)

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See detailLignocellulosic biomass pretreatment impact on the extracted lignins chemical structure
Manara, Panagiota; Zabaniotou, Anastasia; Vanderghem, Caroline ULg et al

Poster (2013, October)

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See detailAre bogs reservoirs for emerging disease vectors? Evaluation of Culicoides populations in the Hautes Fagnes Nature Reserve (Belgium)
Zimmer, Jean-Yves ULg; Losson, Bertrand ULg; Smeets, François ULg et al

Poster (2013, October)

Several species of Culicoides (Diptera: Ceratopogonidae) biting midges serve as biological vec{ors for the bluetongue virus (BTV) and the recently described Schmallenberg virus in northern Europe. since ... [more ▼]

Several species of Culicoides (Diptera: Ceratopogonidae) biting midges serve as biological vec{ors for the bluetongue virus (BTV) and the recently described Schmallenberg virus in northern Europe. since their recent emergence in this part of the continent, these diseases have caused considerable economic losses to the sheep and cattle industries. Much data is nou, âvailable that describe the distribuüon, population dynamics, and feeding habits of these insects. However, little is known regarding the presence of culicoides in unusual habitats such as peaÿ marshes, nor their potential vector capacity. This study evaluated Culicoides biting midges present in the bogs of a Belgian nature reserve compared to those residing at a nearby cattle farm. Culicoides were trapped in 2011 at four different sites (broadleaved and coniferous forested areas, open environments, and at a scientific station) located in the Hautes Fagnes Nature Reserve (Belgium). An additional light trap was operated on a nearby caftle farm. High numbers of biting midges were captured in the marshy area and most of them were Culicoides impunc{atus, a potential vector of BïV and other pâthogens. ln addition, fewer numbers of c. obsoletus/c. scoticus species, C. chiopterus, and C. dewulfi were observed in the bogs compared to the farm. The wet environment and oligotrophic nature of the soil were probably responsible for these changes in the respective populations. A total of 297,808 Culicoides midges belonging to 27 species were identified during this study and 3 of these species (C. sphagnumensis, C. clintoni and C. comosioculatus) were described in Belgium for the first time. [less ▲]

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See detailL’effet des barrages de castors sur le système hydrographique
Denis, Anne-Cécile ULg; Petit, François ULg; Levecq, Yannick ULg et al

Poster (2013, October)

L’augmentation croissante des populations de castors sur nos rivières ces dernières années n’est pas sans conséquence notamment sur la géomorphologie et l’hydrologie des fonds de vallée. En effet, les ... [more ▼]

L’augmentation croissante des populations de castors sur nos rivières ces dernières années n’est pas sans conséquence notamment sur la géomorphologie et l’hydrologie des fonds de vallée. En effet, les barrages construits par les castors constituent des pièges à sédiments susceptibles d’entrainer une incision en aval par déficit en sédiments. La présence de barrages a également pour principal effet de réduire localement la vitesse du courant et de réguler les débits. De plus, les barrages créés par les castors constituent de véritables obstacles à l’écoulement qui peuvent engendrer une modification du tracé du cours d’eau voir du style fluvial. Enfin, en cas de destruction des barrages, le lâcher soudain d’un volume d’eau conséquent peut engendrer un effet « domino » sur les barrages situés en aval entrainant une évacuation importante des sédiments et une incision du cours d’eau. En région Wallonne, il existe plus de 150 barrages de castor. Une analyse récente de leur localisation montre que le castor s’installe principalement sur des rivières ardennaises de dimension modeste mais également sur des rivières de Lorraine et de Famenne. Les barrages sont généralement observés sur des cours d’eau plutôt incisé, en tête de bassin et dans des plaines alluviales plutôt étroites. Différents stades et modes de construction des barrages ont été mis en relation avec la morphologie des rivières. Il en ressort que ces différences impliquent des processus spécifiques de rupture éventuelle de ces barrages. Ces différents aspects ont été plus particulièrement étudiés dans deux rivières ardennaises (la Chavanne et la Lienne). [less ▲]

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See detailImpact of growth rate on the mechanical properties of Douglas-fir grown in Wallonia (Southern Belgium)
Pollet, Caroline; Henin, Jean-Marc; Jourez, Benoît ULg et al

Poster (2013, October)

Timber is traditionally the main purpose of Douglas-fir in Europe. However, some uncertainties remain concerning the sylviculture that should be applied in order to maximise girth growth rate (GR) without ... [more ▼]

Timber is traditionally the main purpose of Douglas-fir in Europe. However, some uncertainties remain concerning the sylviculture that should be applied in order to maximise girth growth rate (GR) without affecting the good mechanical properties of the wood. So, the present study aimed at assessing to what extent the GR of Douglas-firs grown in Wallonia influences the mechanical properties of wood clear samples. The modulus of elasticity (E) and static bending strength (σf) were measured according to NF B51-016 and NF B51-008 and are discussed according to the ring width measured on the samples, as well as on the growth rate of the trees and of the stands, for both juvenile and mature wood. This assessment will help to provide sylviculture guidelines for foresters. The experimental material was derived from 11 Douglas-fir stands distributed all over Wallonia, Southern Belgium. At the time of felling, the age of the stands ranged from 41 to 69 years old. In each stand, six trees were felled, their girth varying from 120cm to 179 cm. As a consequence of the sampling methodology the growth rate of the trees ranged from 3 mm to 7 mm. From the 66 butt logs, 274 and 884 clear samples were taken in the juvenile and mature wood respectively. This research evidenced that: - Whatever the GR, the mean values of E and σf in the juvenile wood are 20% lower than those in the mature wood; - At the tree level, the mean E and σf of the samples taken from trees with ring width>5mm are about 10% lower than those of the samples taken from trees with ring width<5mm, whether considering juvenile or mature wood; - At the stand level and regardless to the type of wood (juvenile/mature), the mean E and σf of the samples originating from stands with mean girth increment>3cm/year are respectively 5% and 9% lower than those of the samples originating from stands with mean girth increment <3cm/year. This observation should lead the forest manager to consider carefully sylvicultural practices that would induce a too fast juvenile growth; high growth rate in the mature wood do not appear to be a problem considering the properties studied here. One should however take into account the impact of the growth rate on the singularities of the boards. [less ▲]

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See detailEffectiveness of case management for maintaining frail older persons at home - intermediate results
Van Durme; Schmitz, Olivier; Cès, Sophie et al

Poster (2013, October)

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See detailImpact of sludge storage duration on its dewatering and drying ability
Pambou, Yvon-Bert ULg

Poster (2013, October)

Annual production of sewage sludge in Europe is estimated at more than twelve million tons of dry matter. Use in agriculture and incineration are the main ways of valorization. In this context, sludge ... [more ▼]

Annual production of sewage sludge in Europe is estimated at more than twelve million tons of dry matter. Use in agriculture and incineration are the main ways of valorization. In this context, sludge drying appears as an essential step after mechanical dewatering. It reduces the costs of storage and transport, allows the stabilization and the hygienization of sludge while increasing its calorific value. However, sludge is a colloidal system in which particle form a stable suspension in water, making him difficult to be separated from water. The addition of polyelectrolytes chemical is necessary to help the sludge particles to agglomerate into large flocs that can be separate by mechanical dewatering. Before studying experimentally the influence of polymer’s type and dosage on dewatering performances and subsequent drying behaviour, it is necessary to assess the sludge variability during storage duration, because sludge is a highly fermentable material whose properties and composition can rapidly change. [less ▲]

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See detailRelative Contribution of Walking Speed, Ataxia and Gait asymmetry to the Composition of Gait in Multiple Sclerosis
PHAN BA, Remy ULg; Pierard, Sébastien ULg; LOMMERS, Emilie ULg et al

Poster (2013, October)

Introduction - Objective: Walking speed measured according to the T25FW is the most widely used descriptor of gait in MS clinical research and practice but other dimensions influencing gait variance exist ... [more ▼]

Introduction - Objective: Walking speed measured according to the T25FW is the most widely used descriptor of gait in MS clinical research and practice but other dimensions influencing gait variance exist according to alternative gait analysis methods. The relative importance of these different dimensions of gait relatively to its variance is unknown. Methods: We measured the performances of persons with MS and healthy subjects on the T25FW and the Timed 20-Meter Walk (T20MW) performed in tandem with a new gait analysis system (GAIMS). We performed a factorial analysis of variance to underline the main dimensions influencing gait variance and observed their composition. Findings - Conclusion: The main factor influencing gait variance in conventional walk tests is mostly composed of features related to walking speed. Balance, gait asymmetry and variability also participate to this variance but to a lesser extent. The inverse is observed in tests performed in tandem gait. [less ▲]

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See detailLignin as a raw material for industrial materials applications
Richel, Aurore ULg; Vanderghem, Caroline ULg; Jacquet, Nicolas ULg et al

Poster (2013, October)

Native lignin is an abundant biopolymer on earth and represents 15-30% by weight of the lignocellulosic biomass. Lignin is a heterogeneous cross-linked polymer composed of phenylpropane units (guaiacyl ... [more ▼]

Native lignin is an abundant biopolymer on earth and represents 15-30% by weight of the lignocellulosic biomass. Lignin is a heterogeneous cross-linked polymer composed of phenylpropane units (guaiacyl, syringyl or p-hydroxyphenyl) linked together by a panel of specific ether or carbon-carbon bonds.[1] Nowadays, large amounts of lignins and lignin-based wastes are available and originate either from the pulp and paper manufacturing or from the production of bioethanol from lignocellulose. [2] Typically, these lignins are dedicated to energetic purposes by combustion. In recent years however, novel axes for high added value applications have emerged and concern, notably, the use of lignin as performance products (e.g. polymer additives, binders) or specialty chemicals (e.g. surface-active agents) for materials applications.[3] Herein, several applications of lignin in materials sciences with industrial issues are presented. A correlation is established between the extraction processes from lignocellulosic materials and the chemical structure and physico-chemical properties of lignins.[4] Our research group has also developed new methodologies for the extraction of highly pure lignins from several starting materials, including food wastes, herbaceous raw materials and wood biomass. These methodologies include microwave-assisted extraction and two-step conventional pretreatment involving steam explosion. These methodologies are described in this presentation. [less ▲]

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See detailComet dust profiles from PACS images obtained in the framework of the HSSO project
Opitom, Cyrielle ULg; Bockelée-Morvan, D.; Hutsemekers, Damien ULg et al

Poster (2013, October)

In the framework of the HssO project the Herschel PACS instrument acquired images of 7 comets between June 2010 and February 2013. Three of these comets have been imaged at several heliocentric distances ... [more ▼]

In the framework of the HssO project the Herschel PACS instrument acquired images of 7 comets between June 2010 and February 2013. Three of these comets have been imaged at several heliocentric distances allowing us to follow up the evolution of the dust coma . Radial profiles have been derived for each image. We measured flux densities at 70, 110 and 160 μm in order to determine the comet dust production rate. In some cases, after deconvolution by the instrumental PSF, we might have detected the nucleus signal in the central pixels. [less ▲]

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See detailÉvaluation de la qualité hydromorphologique dans le cadre de projet de restauration de cours d’eau
Regnier, Maxime; Peeters, Alexandre ULg; Verniers, Gisèle

Poster (2013, October)

Walphy.be

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See detailSuivi à long terme d’un chantier de protection de berge par techniques végétales : La Berwinne à la Folie
Hallot, Eric ULg; Peeters, Alexandre ULg; Houbrechts, Geoffrey ULg et al

Poster (2013, October)

Depuis 2000, le Service Public de Wallonie a réalisé plusieurs chantiers de protection de berge ou de réaménagement de cours d’eau par techniques végétales. Parmi ceux-ci, le site de la Berwinne à La ... [more ▼]

Depuis 2000, le Service Public de Wallonie a réalisé plusieurs chantiers de protection de berge ou de réaménagement de cours d’eau par techniques végétales. Parmi ceux-ci, le site de la Berwinne à La Folie (Berneau) a fait l’objet d’aménagement au mois de mars 2001. Trois épis de longueur croissante, légèrement orientés vers l’amont, reliés par des peignes latéraux, avaient été installés une vingtaine de mètres à l’amont d’une berge concave dans le but de limiter son recul tout en préservant sa verticalité. Cette berge verticale constituait un habitat écologique très intéressant notamment pour la nidification des hirondelles de rivage. La zone de calme ainsi créée limitait l’érosion mais possédait des vitesses suffisamment élevées en période de hautes eaux pour permette le remaniement des sédiments. Un suivi géomorphologique du site, basé principalement sur des analyses topographiques, hydrologiques et sédimentologies, est réalisé depuis 2000. Les premières observations avaient mis en évidence un réajustement rapide mais localisé du cours d’eau aux aménagements, suivi d’une période de stabilisation entre 2002 et 2004. Par la suite, une réactivation entre 2004 et 2007 était observée. Nous avions conclu qu’un suivi de plus longue durée était indiqué afin de pouvoir quantifier la durée d’adaptation et l’extension réelle de tels aménagements. De nouveaux levés géomorphologiques réalisées en 2013 confirment la nécessité de réaliser des suivis à long terme car ils montrent que l’adaptation de la Berwinne aux aménagements est toujours en cours et concerne un linéaire beaucoup plus important vers l’aval que le seul site d’intervention. [less ▲]

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See detailImpact of sludge storage duration on its dewatering and drying ability Y.B Pambou, T. Salmon, L. Fraikin, M. Crine, and A. Léonard
Pambou, Yvon-Bert ULg

Poster (2013, October)

Annual production of sewage sludge in Europe is estimated at more than twelve million tons of dry matter. Use in agriculture and incineration are the main ways of valorization. In this context, sludge ... [more ▼]

Annual production of sewage sludge in Europe is estimated at more than twelve million tons of dry matter. Use in agriculture and incineration are the main ways of valorization. In this context, sludge drying appears as an essential step after mechanical dewatering. It reduces the costs of storage and transport, allows the stabilization and the hygienization of sludge while increasing its calorific value. However, sludge is a colloidal system in which particle form a stable suspension in water, making him difficult to be separated from water. The addition of polyelectrolytes chemical is necessary to help the sludge particles to agglomerate into large flocs that can be separate by mechanical dewatering. Before studying experimentally the influence of polymer’s type and dosage on dewatering performances and subsequent drying behaviour, it is necessary to assess the sludge variability during storage duration, because sludge is a highly fermentable material whose properties and composition can rapidly change. [less ▲]

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See detailMolecular mechanisms of type I collagen-induced apoptosis in breast carcinoma cells
Maquoi, Erik ULg; Assent, Delphine ULg; Foidart, Jean-Michel ULg et al

Poster (2013, September 27)

Objective: As invading breast carcinoma cells breach the underlying basement membrane, they become confronted with a dense three-dimensional reactive stroma dominated by type I collagen. To develop ... [more ▼]

Objective: As invading breast carcinoma cells breach the underlying basement membrane, they become confronted with a dense three-dimensional reactive stroma dominated by type I collagen. To develop metastatic capabilities, invading tumour cells must acquire the capacity to negotiate this hostile microenvironment. By enmeshing cells in a dense fibrillar network, type I collagen acts as a physical barrier for cell migration as well as an endogenous antigrowth signal, partly by inducing apoptosis in epithelial cells. Aberrant cell survival resulting from an acquired resistance toward apoptosis represents a prominent hallmark of cancers. However, the molecular mechanisms implicated in collagen-induced apoptosis remain poorly defined. Here, we investigate the molecular mechanisms by which type I collagen induces apoptosis in breast carcinoma cells and identify MMP-14, a membrane-anchored matrix metalloproteinase, as a key anti-apoptotic factor. Methods: To investigate the induction of apoptosis by collagen, human breast adenocarcinoma MCF-7 cells overexpressing or not MMP-14 were plated on plastic plates or embedded within three dimensional type I collagen gels (Col3D). Cell death was evaluated by measuring cytoplasmic histone-associated DNA fragments (Cell Death Detection ELISA). The percentage of cells with an apoptotic nuclear morphology was also determined. The interactions between cancer cells and Col3D were analyzed by confocal microscopy and the impact of Col3D on the transcriptome of cancer cells was investigated using Illumina HT-12 BeadArrays. Results: When cultured within Col3D gels, MCF-7 cells displayed a round morphology and a cell death characterized by a Z-VAD-FMK-dependent chromatin condensation, nuclear segmentation and oligonucleosomal DNA fragmentation was induced. Transfection of MCF-7 cells with MMP-14 cDNA promoted the interactions between cells and collagen and prevented apoptosis. A transcriptomic analysis revealed that culturing MCF-7 cells within Col3D altered the expression of about 700 genes, irrespective of MMP-14 expression. Col3D modulated the expression of several apoptosis-related genes. Interestingly, MMP-14 activity was sufficient to prevent the Col3D-dependent induction of Bcl2-Interacting Killer (BIK), a pro-apoptotic member of the Bcl-2 family. Conclusions: Our results shed light on the molecular mechanisms by which a collagen-rich microenvironment triggers apoptosis in invading breast cancer cells. Furthermore, we demonstrate that MMP-14 promotes tumour progression by circumventing apoptosis. [less ▲]

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See detailPILOT PROJECT IN CHR-LIEGE: INVITING SIBLINGS OF CHILDREN WITH CANCER TO A CREATIVE AND EXPRESSIVE WEEK-END WITH PSYCHOLOGISTS AND ONCOLOGIST
Forget, Patricia; Badot, Isabelle; Missotten, Pierre ULg et al

Poster (2013, September 27)

The siblings week end with the psycho-medical team was highly successful It opens another way to improve the care of the siblings Questionnary forms should be developped in the future to evaluate the real ... [more ▼]

The siblings week end with the psycho-medical team was highly successful It opens another way to improve the care of the siblings Questionnary forms should be developped in the future to evaluate the real psychological impact [less ▲]

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See detailResorcinol-Formaldehyde Carbon Xerogels as Anode Material for Lithium-Ion Battery: Synthesis, Grinding and Coating on Current Collector
Piedboeuf, Marie-Laure ULg; Léonard, Alexandre ULg; Pirard, Jean-Paul ULg et al

Poster (2013, September 24)

Rechargeable lithium-ion batteries show great advantages over traditional batteries and are extensively used for consumer electronic devices due to their high energy density and long cycle life. However ... [more ▼]

Rechargeable lithium-ion batteries show great advantages over traditional batteries and are extensively used for consumer electronic devices due to their high energy density and long cycle life. However, the improvement of performance of current lithium-ion batteries requires the optimization of the materials used (electrolyte and electrodes). Therefore, tremendous efforts have been dedicated to exploring new materials with high capacity, excellent cycling performance, low cost and high safety features [1-3]. As an example, carbon xerogels are promising candidates in the development of new high performance C-based anode materials for Li-ion batteries, since such carbonaceous materials show very small changes of volume during the charge/discharge process, providing a long cycle life. Nevertheless, hard carbons also exhibit quite high irreversible capacity losses due to their intrinsic high microporosity [4]. To overcome these disadvantages, the structural and textural characteristics need to be carefully controlled. Also, due to the different morphology of these materials compared to graphite, the deposition of carbon xerogels on current collectors needs to be studied in detail. In this work, porous carbon xerogels have been synthesized from Resorcinol-Formaldehyde mixtures by adjusting the pH of the solution in order to obtain different mesopore sizes. Monoliths of carbon xerogels are obtained after drying of the polymer gel and pyrolysis [5]. These monoliths have been ground by two different methods and particle size distributions were measured by granulometry. Mercury intrusion porosimetry and nitrogen adsorption techniques (BET) have been used to characterize the pore texture of the monolithic and the powder materials. Different conditions have been used for the mixing of carbon xerogels with a binder and a solvent to form slurries. The latter have been cast on a copper foil using bar coating with different openings. After evaporation of the solvent, the resulting coatings were analyzed using scanning electron microscopy (SEM) for the morphology and their thickness was monitored by profilometry. First results indicate that the method of grinding has no influence on the final particle size distribution of the powder. The structural features of the carbon xerogels is well preserved for particles down to one micrometer. Nevertheless, a study of grinding duration shows that additional particles with sizes close to that of the porosity of the carbon appear. As a consequence, the grinding conditions were chosen so as to obtain a compromise between particles small enough to realize a coating on a current collector and particles large enough to maintain the carbon gel structural characteristics. References 1) Goodenough J.B., Kim Y. J. Power Sources 2011; 196(16): 6688-6694. 2) Bruce P.G. Solid State Ionics 2008; 179: 752-760. 3) Cairns A. J., Albertus P. Ann. Rev. Chem. Biomol. Eng. 2010; 1: 299-320. 4) Tran T., Yebka B., Song X., Nazri G., Kinoshita K., Curtis D. J. Power Sources 2000; 85: 269-278. 5) Job N., Théry A., Pirard R., Marien J., Kocon L., Rouzaud J., Béguin F., Pirard J. Carbon 2005; 43: 2481-2494. [less ▲]

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See detailApplication of the Data-Interpolating Variational Analysis (DIVA) to sea-level anomaly measurements in the Mediterranean Sea
Troupin, Charles ULg; Barth, Alexander ULg; Beckers, Jean-Marie ULg et al

Poster (2013, September 23)

In ocean sciences, numerous techniques are available for the spatial interpolation of in situ data. These techniques mainly differ in the mathematical formulation and the numerical efficiency. Among them ... [more ▼]

In ocean sciences, numerous techniques are available for the spatial interpolation of in situ data. These techniques mainly differ in the mathematical formulation and the numerical efficiency. Among them, DIVA, which is based on the minimization of a cost function using a finite-element technique (figure 1). The cost function penalizes the departure from observations, the smoothness or regularity of the gridded field and can also include physical constraints. The technique is particularly adapted for the creation of climatologies, which required a large to several regional seas or part of the ocean to generate hydrographic climatologies. Sea-level anomalies (SLA) can be deduced from satellite-borne altimeters. The measurements are characterized by a high spatial resolution along the satellite tracks, but often a large distance between neighbour tracks. This implies the use of simultaneous altimetry missions for the construction of gridded maps. An along-track long wave-length error (correlated noise, e.g. due to orbit, residual tidal correction or inverse barometer errors) also affects the measurement and has to be taken into account in the interpolation. In this work we present the application and adaptation of Diva to the analysis of SLA in the Mediterranean Sea and the production of weekly maps of SLA in this region. Determination of the parameters The two main parameters that determines an analysis with DIVA are the correlation length (L) and the signal-to-noise ratio (SNR). Because of the particular spatial distribution of the measurements, the tools implemented in Diva for the analysis parameter determination tend to underestimate L and overestimate SNR, leading to noisy analysis (the observation constraint dominates the regularity constraint). Some adaptations of the tools are necessary to solve this issue. Numerical cost Because of the large number of observations to be processed (in comparison with in situ measurements on a similar period), the interpolation method employed is expected to be numerically efficient. Improvements in the implementation of Diva further improved the numerical performance of the method, especially thanks to the use of a parallel solver for the matrix inversion. The performance of finite-element mesh generator was also enhanced, so that interpolation of a data set of more than 1 million data points on a 100-by-100 grid can be performed in a few minutes on a personal laptop. Analysis and error field The analysis and error fields obtained over the Mediterranean Sea are compared with the available gridded products from AVISO. Different ways to compute the error field are compared. The impact of the use of multiple missions to prepare the gridded fields is also examined. [less ▲]

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See detailAnalytical study of “La Famille Soler” by Picasso: from the Blue Period to Cubism
Defeyt, Catherine ULg; Vekemans, Bart; Vandenabeele, Peter et al

Poster (2013, September 23)

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See detailOrthographic learning in adult skilled readers
Binamé, Florence ULg; Poncelet, Martine ULg

Poster (2013, September 21)

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See detailPerception du pouvoir entre visiteurs et visités dans la pratique du tourisme dit « ethnique »: Au-delà des oppositions, authentique / simulacre
Lekane Tsobgou, Dieudonné ULg; Schmitz, Serge ULg

Poster (2013, September 20)

La pratique du tourisme est prise sous l'angle d'une confrontation entre les peuples « visiteurs » et les peuples « visités » (Demanget, 2007). L’exotisme culturel des populations autochtones est la ... [more ▼]

La pratique du tourisme est prise sous l'angle d'une confrontation entre les peuples « visiteurs » et les peuples « visités » (Demanget, 2007). L’exotisme culturel des populations autochtones est la principale attraction (Harron et al. 1992). Ainsi, une modification de l’équilibre et une rencontre bilatérale semblent plus opaques. Dès lors, les produits authentiques ou les productions instrumentalisées déterminent la position de pouvoir détenus par les visiteurs ou par les visités. Les promoteurs touristiques cherchent avant tout leur gain d’où l’offre parfois des produits issus de simulacre aux visiteurs en mal d’exotisme. Comment illustrer les jeux de pouvoir et de marchandage qui organisent les rencontres plus ou moins authentiques entre visités et touristes ? Les pratiques du tourisme ethnique en Afrique (Cameroun, Madagascar) et en Asie ( Birmanie, Thailande) nous ont servi d'outils d'analyse et d'expérimentation du jeu de pouvoirs entre visités et visiteurs. [less ▲]

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See detailStudy of the estrogenicity of pure compound migrate from plastic food contact materials
Simon, Coraline ULg; Oghena, M.; Covaci, A. et al

Poster (2013, September 19)

Detailed reference viewed: 19 (2 ULg)
See detailDrug delivery systems based on amphiphilic polyphosphate-copolymers
Vanslambrouck, Stéphanie ULg; Clement, Benoît ULg; Riva, Raphaël ULg et al

Poster (2013, September 18)

Thanks to their biocompatibility, biodegradability and their structure similar to natural biomacromoleculesn such as nucleic acids, polyphosphates (PPhos) are of prime interest as biomaterials. In ... [more ▼]

Thanks to their biocompatibility, biodegradability and their structure similar to natural biomacromoleculesn such as nucleic acids, polyphosphates (PPhos) are of prime interest as biomaterials. In contrast to poly--caprolactone and polylactides, PPhos properties and functionality are easily tuned via the nature of the pendant group of the starting cyclic monomer. For example, by varying the length of the alkyl chain the hydrophobicity of the PPhos can be adjusted. In this work, an efficient organo-catalytic system was developed to synthesize a series of amphiphilic diblock copolymers, i.e. poly(ethylene oxide)-b-polyphosphate (PEO-b-PPhos) by ring-opening polymerization of cyclic phosphates. This novel approach prevents metallic residues to polute the final product, and which is highly desirable when biomedical applications are foreseen. For drug delivery application, the micellization of these novel diblock copolymers in aqueous media was investigated, as well as, encapsulation of an hydrophobic drug. Data on, the influence of the polyphosphate nature of the polymer on drug loading will be presented. [less ▲]

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See detailNitrous oxide emissions using quantum cascade laser spectrometry over a production crop: preliminary results
SALERNO, Giovanni ULg; Aubinet, Marc ULg; Joly, Joly et al

Poster (2013, September 18)

Amongst the greenhouse gases, nitrous oxide is recognized as having the greatest greenhouse forcing potential and as being the third in terms of radiative forcing. Agriculture is known to be the major ... [more ▼]

Amongst the greenhouse gases, nitrous oxide is recognized as having the greatest greenhouse forcing potential and as being the third in terms of radiative forcing. Agriculture is known to be the major anthropic emitter. This work is part of the FERTECOL project and its objective is to measure the emissions of nitrous oxide by a production crop with an eddy covariance system. The measurements extent over the growth period, cover a large range of climatic conditions and capture peak events associated with fertilization. The measurements, started in April 2013, are carried at the Lonzée Terrestrial Observatory (50°33'5.83"N- 4°44'46.22"E). On this year, the crop is planted with winter wheat. A Quantum Cascade Laser Absorption Spectrometer (QCLAS, GSMA, France) is used to measure nitrous oxide as well as water vapor and carbon dioxide at a frequency of 5 hertz. The fluxes are computed using the Eddy Covariance technique adapting standards quality and corrections procedures set up for CO2 fluxes to N2O. Standard meteorological measurements are performed in parallel. The analysis will present response of the fluxes to environmental variables as well as to fertilization events during the season. [less ▲]

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See detailElp3 is required for initiation of colon cancer
Ladang, Aurélie ULg; Heukamp, L; Buettner, R et al

Poster (2013, September 18)

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See detailReplication of large-scale epistasis studies: an example on ankylosing spondylitis
Bessonov, Kyrylo ULg; Van Steen, Kristel ULg

Poster (2013, September 17)

Ankylosing spondylitis (AS) is a common form of inflammatory arthritis occurring in approximately 5 out of 1,000 adults of European descent. Recently, the Australo-Anglo-American Spondyloarthritis ... [more ▼]

Ankylosing spondylitis (AS) is a common form of inflammatory arthritis occurring in approximately 5 out of 1,000 adults of European descent. Recently, the Australo-Anglo-American Spondyloarthritis Consortium and the WTCCC2 showed that polymorphisms of ERAP1 only affect AS risk in HLA-B27-positive individuals, hereby establishing an interaction between ERAP1 and HLA in the TASC, WTCCC2 and replication datasets [2,5]. We were able to confirm this interaction although using other SNPs. In this study, we use the aforementioned data from WTTCC2 on AS to address unresolved issues when performing large-scale SNP-SNP interaction studies, so as to better guarantee “stable” and “truly replicable” results. These issues are 1) the choice of variable selection method (e.g., of known loci mapping to genes part of know pathways), 2) the choice of SNPs representing a genomic region (e.g., SNPs with modest versus negligible LD between them), 3) the choice of analysis method (e.g., regression-based versus data-reduction (non-parametric) based), 4) different adjustment schemes for lower-order effects (using additive/co-dominant genetic models). We show that even modest changes in 1)-4) may give rise to quite varying epistasis findings for AS, and motivate some “optimal” choices via extensive simulation studies. In this work we rely on a minimal GWAI protocol for genome-wide epistasis detection using SNPs, as developed in our lab [6][9], using the advanced non-parametric Model-Based Multifactor Dimensionality Reduction (MB-MDR) method [1] and an adapted [*] BOolean Operation-based Screening and Testing (BOOST) algorithm [4]. [*] A BOOST [4] like implementation based on the original BOOST algorithm which accounts for missing genotypes [less ▲]

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See detailNumerical simulation of the electrical characteristics of CIGS/CdS/ZnO solar cell heterostructures
Amand, Julien ULg; Nguyen, Ngoc Duy ULg

Poster (2013, September 17)

The electrical characteristics of CIGS-based solar cell heterostructure have been simulated by numerically solving the basic semiconductor equations by means of a finite differences method based on a ... [more ▼]

The electrical characteristics of CIGS-based solar cell heterostructure have been simulated by numerically solving the basic semiconductor equations by means of a finite differences method based on a Scharfetter-Gummel discretization scheme. The electric potential, electric field, carrier concentrations, current densities and recombination rates are obtained as function of the space coordinate and the bias voltage. Starting with the analysis of a single absorber layer structure sandwiched between two metal electrodes, we subsequently studied the properties of the CIGS/ZnO pn heterojunction and the influence of the buffer layer thickness in the CIGS/CdS/ZnO on the cell electrical response. A special focus was also given to the influence of grain boundaries in the bulk of CIGS depending on the defects nature and concentration. [less ▲]

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See detailCharacterization of structures with a complex disposition of YBCO coated conductors for magnetic shielding applications
Wera, Laurent ULg; Fagnard, Jean-François ULg; Levin, G. A. et al

Poster (2013, September 16)

An efficient superconducting magnetic shield can be built as an assembly of YBCO 2G coated conductor sections. Each section is milled and placed around a cylindrical support in order to form a joint free ... [more ▼]

An efficient superconducting magnetic shield can be built as an assembly of YBCO 2G coated conductor sections. Each section is milled and placed around a cylindrical support in order to form a joint free superconducting loop where persistent currents can flow and provide a strong attenuation of a magnetic field. Our previous works have shown that this assembly is able to shield an axial quasi static (“DC”) magnetic field and that the shielding performances depend on the aspect ratio and the number of layers. The purpose of the present work is to study experimentally the shielding efficiency of several structures with a more complex orientation and position of YBCO coated conductors. Our aim is to design a magnetic shield that would be able to shield a magnetic field directed at any angle with respect to the superconducting loops. Such a structure can be obtained by placing pairs of coated conductors sections along three orthogonal axes. All experiments are carried out at 77K. The structure is subjected to a quasi-static (“DC”) magnetic field. A Hall probe measures the three components of the local magnetic induction inside the assembly as a function of the applied magnetic induction. The shielding efficiency of the structure is characterized as a function of (i) the magnetic field amplitude, (ii) the position of the Hall probe along the three axes, and (iii) the angles between the applied magnetic field and each axis. The experimental results allow us to determine the shielding efficiency in the central part of the new 3-axes structure. Although the shielding efficiency is lowered with respect to that of the traditional 1-axis-coil geometry, measurements at different field orientations allow us to identify the role played by each of the pairs of coils in screening the external magnetic field. [less ▲]

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See detailClass V β Tubulin during the development of the organ of Corti in rat
Renauld, Justine ULg; Thelen, Nicolas ULg; Johnen, Nicolas ULg et al

Poster (2013, September 13)

In eutherian mammals, the organ responsible for the transduction of sound waves into nerve impulses is called the organ of Corti. This structure located within the cochlea, a portion of the inner ear, is ... [more ▼]

In eutherian mammals, the organ responsible for the transduction of sound waves into nerve impulses is called the organ of Corti. This structure located within the cochlea, a portion of the inner ear, is composed by two types of cells: sensory hair cells and non-sensory supporting cells. All these cells are distributed according to a specific arrangement along the whole length of the cochlea. A feature of the organ of Corti’s supporting cell is the presence of an abundant cytoskeleton. This one is mainly composed of microtubules, structures make up by tubulin heterodimers. The heterodimers consist of one molecule of α tubulin and one molecule of β tubulin. β tubulin isotypes are highly conserved in evolution and differ by only a few amino acid residues, implying that the isotypes may have functional significance. Organ of Corti’s supporting cells are constituted by class V β-tubulin, a minor mammalian tubulin (Bhattacharya et al., 2008). Moreover, their microtubules are formed by 15 protofilaments instead of the canonical 13, a unique fact among vertebrates (Banerjee et al., 2008). Such a configuration of protofilaments has been observed in C. elegans’ neurons which are responsible for the mechanosensory sense of touch (Bounoutas et al., 2009). It was also shown that these 15 protofilaments microtubules were essential to the proper functioning of these mechanosensory neurons (Bounoutas et al., 2009). Here we present the spatiotemporal localization of class V β-tubulin during the development of the organ of Corti in rats from embryonic day 18 (E18) until P25 (25th postnatal day). For this purpose, we have used immunolabelings on cryosections of whole cochlea. Our preliminary results demonstrate that class V β-tubulin has a unique distribution in the cochlea, being restricted to supporting cells, especially in pillar cells. [less ▲]

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See detailProteomic study of lumbar spinal cord after quadricipital eccentric exercise
Lacrosse, Zoé ULg; Hody, Stéphanie ULg; Leprince, Pierre ULg et al

Poster (2013, September 12)

Eccentric muscle contractions are characterized by an increase of muscle tension as it lengthens (slowering movements). Unaccustomed or intense eccentric exercise causes “Delayed-Onset Muscle Soreness” ... [more ▼]

Eccentric muscle contractions are characterized by an increase of muscle tension as it lengthens (slowering movements). Unaccustomed or intense eccentric exercise causes “Delayed-Onset Muscle Soreness” (DOMS). DOMS include muscle pain that appears 24 to 72 hours after exercise, but also stiffness, edema and muscle proteins release in plasma as a hallmark of muscle fibers injuries. The only systematic intervention that brings a muscle protection against DOMS is to realize submaximal eccentric contractions with a progressively increased intensity. The mechanism of this protection, called the “Repeated Bout Effect” (RBE), is not understood. However, it is likely explained by cellular, mechanical and neural theories [Scand.J.Med.&Sci.Sports, 13, 88, 2003]. The objective of this study is to better understand which neural signal is released in the muscle synapse and which brings protection by RBE. Male adult mice (C57BL6) were randomly divided into downhill running (DHR), uphill running (UHR) and untrained control (CONT) groups (n=4/group). DHR group is characterized by eccentric contractions of the quadriceps while UHR is concerned by concentric contractions. Running groups performed a warm-up of ten minutes followed by an interval exercise on an inclined treadmill at a velocity of 20cm/s. The latter consisted of running 18 bouts of 5 minutes interspersed with a 2 minutes rest. Lumbar spinal cord was dissected 24h after the race. Nuclear and cytoplasmic proteins were separately extracted and subjected to a 2D-DIGE analysis coupled with mass spectrometry. We do not observe any cytoplasmic protein modification while in the nuclear extract, seven spots were more abundant in eccentric group and four in concentric group in comparison with control group. The mass spectrometry of these proteins reveals that they are implicated in axoplasmic transport. At 24 hours, too few proteins modifications were detected in lumbar spinal cord, maybe as a consequence of a too short period between race and euthanasia. Implication of axoplasmic transport comforts our starting hypothesis that nervous system is able to protect muscle during the RBE by a synthesis and then a synaptic release of molecules modifying the muscle physiology. [less ▲]

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See detailTRAPPIST monitoring of comet C/2012 F6 (Lemmon)
Opitom, Cyrielle ULg; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

Poster (2013, September 12)

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See detailA water-soluble salt of curcumin (NDS27) inhibits myeloperoxidase and NADPH oxidase activities, two major enzymes of neutrophils.
Derochette, Sandrine ULg; Mouithys-Mickalad, Ange ULg; Deby-Dupont, Ginette et al

Poster (2013, September 11)

Neutrophils (PMNs) produce reactive oxygen species (ROS) to kill pathogenic agents. After appropriate stimulation, leading to the activation of protein kinase C (PKC), the cytosolic subunits of the NADPH ... [more ▼]

Neutrophils (PMNs) produce reactive oxygen species (ROS) to kill pathogenic agents. After appropriate stimulation, leading to the activation of protein kinase C (PKC), the cytosolic subunits of the NADPH oxidase (Nox2) are phosphorylated and translocated to the membrane flavocytochrome b558, forming the active enzyme which produces superoxide anion (O2●-). From O2●- derives H2O2 used by the PMNs myeloperoxidase (MPO) to form strong oxidant species. Many human and animal pathologies with fatal issue are associated with uncontrolled activation of PMNs. The modulation of enzymes implied in ROS production is thus a primary target to manage excessive inflammatory events. For this purpose, we evaluated the effects of NDS27, a water-soluble salt of curcumin combined with hydroxypropyl-β-cyclodextrin, on the activities of PKC, Nox2 and MPO. PKC activation was determined by western blotting with specific antibodies against phosphorylated PKC in extracts from PMNs after their incubation or not with NDS27. A cell-free assay was used to evaluate the effect of NDS27 before or after the assembly of Nox2 subunits. MPO activity was tested by the SIEFED technique in which NDS27 was pre-incubated with the enzyme and discarded before its activity measurement. An inhibition of PKC phosphorylation and Nox2 activity were observed at respectively 10-4 and 10-5 M of NDS27. The Nox2 inhibition was more pronounced when NDS27 was added before the assembly stimulation, suggesting a direct action of NDS27 on the subunits translocation. NDS27 also dose-dependently decreased the activity of MPO (21 % at 10-5 M), indicating an interaction with the enzyme structure. Our results demonstrated that NDS27 is a potent inhibitor of the two major enzymes responsible for ROS production in PMNs, and also acts on the activation cascade of Nox2. The modulatory effect of NDS27 towards the oxidant activity of PMNs opens therapeutic perspectives to control pathologies with excessive inflammatory reactions. [less ▲]

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See detailPrevalence and Richness of Gastrointestinal Parasites of Capuchins (Cebus albifrons) Interacting with humans in the Ecuadorian Amazon
Ramirez, William; Martin, Sarah ULg; Carrillo Bilbao, Gabriel Alberto et al

Poster (2013, September 10)

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See detailThe Multicoloured Asian Ladybird, invasive or not in agroecosystems ?
Vandereycken, Axel ULg; Durieux, Delphine ULg; Fassotte, Bérénice ULg et al

Poster (2013, September 10)

The Multicoloured Asian Ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is known to thrive principally in shrubby and arboreal habitats. Its occurrence in agroecosystems remains poorly ... [more ▼]

The Multicoloured Asian Ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is known to thrive principally in shrubby and arboreal habitats. Its occurrence in agroecosystems remains poorly documented. This study focuses on the occurrence of this exotic species and its seasonal abundance in various field crops. The abundance of adults and larvae of H. axyridis was evaluated over a four-year period, from 2009 to 2012, in four important agronomical crops (wheat, corn, broad bean and potato) in Belgium. A total of 28 aphid predator species were observed including 14 coccinellid species, 13 hoverfly species and one lacewing species. H. axyridis is present and reproduces in all of the four crops studied, with the largest numbers recorded in corn and broad bean crops. In corn, H. axyridis numbers were found to increase over the four inventoried year, reaching 86% of the aphid predators in 2012, while it represented only 15% in 2009. H. axyridis was not always recorded where aphids were abundant, e.g. aphids were abundant on wheat where no H. axyridis were recorded. H. axyridis starts reproducing after the peak in aphid population, suggesting that H. axyridis is able to complete its development by feeding on alternative prey such as larvae and pupae of the same and other species of ladybird and other aphidophagous species. H. axyridis is often considered to be bivoltine but it only completes one generation per year in field crops. The second generation generally develops late in the season in other habitats. Harmonia axyridis is an invasive and an intraguild predator present in high quantities in some specific crops. In these crops, H. axyridis could negatively impact on population of native species due to IGP observed in several other studies. [less ▲]

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See detailLinear formulation of identifying cdes in graphs
Vandomme, Elise ULg; Gravier, Sylvain; Parreau, Aline ULg

Poster (2013, September 09)

Identifying codes were introduced by Karpovsky, Chakrabarty and Levitin in 1998 and can be applied to locate fire in a building using sensors. Buildings are modelled by graphs with rooms as vertices. The ... [more ▼]

Identifying codes were introduced by Karpovsky, Chakrabarty and Levitin in 1998 and can be applied to locate fire in a building using sensors. Buildings are modelled by graphs with rooms as vertices. The placement of sensors in the rooms corresponds to choosing a subset of vertices. Finding a sensor-placement such that the location of a fire in one room can be precisely determined is equivalent to constructing an identifying code in the graph. These are dominating sets of vertices for which the closed neighbourhood of each vertex (i.e., the vertex and its neighbours) has a unique intersection with the set. The problem of finding an identifying code has been widely studied. Yet its formulation as an integer linear problem hasn't been much considered. Let G be a graph with vertex set V, to an identifying code $C\subseteq V$ of $G$ correspond weights x_u (x_u is 1 if u belongs to C, otherwise x_u is 0) satisfying the following : for all vertices u,v * the sum of the x_w for w in the closed neighbourhood of u is at least 1 * the sum of the x_w for w in the symmetric difference of the closed neighbourhoods of u and v is at least 1. Of course, it is interesting to find an identifying code with the smallest possible cardinality. But in general this is a NP-hard problem. A way to obtain bounds on the minimal cardinality is to consider the associated linear problem where the weights x_u are fractional. In the case of vertex-transitive graphs, the minimal cardinality for the fractional case can only take two values which depend on the number of vertices, the degree of the graph and the smallest symmetric difference between any two closed neighbourhoods. We show that for an infinite family of graphs the bound is tight and for another another the bound is far too be reached. [less ▲]

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See detailFree Group and Recognizability
Raskin, Julien ULg

Poster (2013, September 09)

It is well known that recognizability has many algebraic properties. For example, a subset $L$ of the free monoid $\Sigma^*$ is recognizable if and only if there exists a finite monoid $M$, a subset $P ... [more ▼]

It is well known that recognizability has many algebraic properties. For example, a subset $L$ of the free monoid $\Sigma^*$ is recognizable if and only if there exists a finite monoid $M$, a subset $P$ of $M$ and a morphism $f : \Sigma^* \to M$ such that $L = f^{-1}(P)$. These properties allow us to easily define a concept of recognizability in non-free monoids or even in other algebraic structures, such as groups. Our aim is to study the recognizable subsets of the free group $F_X$ generated by $X$. A classical construction of the latter shows that it can be seen as a subset of the free monoid $(X \cup X')^*$, where $X'$ is a set of formal inverses of elements of $X$, endowed with an ad hoc operation. When $X$ is finite, it appears that $F_X$ is a recognizable language of this monoid. It is then natural to wonder if there is a link between recognizability in $F_X$ and recognizability in $(X \cup X')^*$. We show that every recognizable language of $F_X$ is recognizable in $(X \cup X')^*$, and that we can define a class of automata that recognize the recognizable languages of $F_X$. [less ▲]

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See detailClassification of riparian forest species (individual tree level) using UAV-based Canopy Height Model and multi-temporal orthophotos (Vielsalm, Eastern Belgium)
Michez, Adrien ULg; Lisein, Jonathan ULg; Toromanoff, François ULg et al

Poster (2013, September 09)

Introduction : Despite their relatively low area coverage, riparian forests are central landscape features providing several ecosystem services. Nevertheless, they are critically endangered in European ... [more ▼]

Introduction : Despite their relatively low area coverage, riparian forests are central landscape features providing several ecosystem services. Nevertheless, they are critically endangered in European countries by human pressures (livestock grazing, land use conflicts, canalizations, waste water, ...) andalso by natural hazards such as the recent black alder (Alnus glutinosa) extensive decline caused by Phytophthora alni. In this study UAV is used to improve the characterization of riparian areas. Riparian forest species are identified at the individual tree level. The health condition of black alder is assessed. For this purpose a computer based approach has been developped, with low needs of specific operator ability or training. Methods : We used the Gatewing X100 to acquire 16 aerial photographs datasets (7 in classic RGB and 9 in RG NIR) during 5 days (form Augustus to October 2012). We processed a CHM in ArcGIS by combining a national Digital Terrain Model with a photogrammetric DSM generated from a single flight photographs dataset with the "MicMac" opensource platform. The 16 orthophotos were computed with Agisoft Photoscan. Based on the CHM and some basic vegetation index (mean NDVI), a classification/segmentation process was developped in eCognition allowing tree crown extraction. An amount of 113 metrics were computed in eCognition for every tree crown object. The metrics were both derived from the CHM raster and spectral information. Metrics were computed by band (object spectral mean and CHM mean, Harralick entropy, Skewness) but also with band combination (Green NDVI and NDVI). A reference dataset was also acquired through a field survey of 624 individual tree positions accurately localized. The health condition of the black alder was recorded during the field survey. A supervised classification algorithm was developed in R (Random Forest package). Results : Several classification trees were assessed trough global accuracy using the Out Of Bag (OOB) error. The best global accuracy (82%) was obtained when distinguishing the black alder (with no regards for health condition during field survey) from the rest of riparian forest objects. The global accuracy tended to decline when other species were added. When separating healthy black alders from those with symptoms, the global accuracy is 77%. Conclusions : Our study highlights the potential of UAV-based multitemporal orthophotos to identify riparian forest species and health conditions at the tree level. Future studies will focus on quick radiometrics corrections. This could improve global accuracy by reducing the variability caused by illumination conditions [less ▲]

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