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See detailOn Generalized Hölder-Zygmund Spaces
Kreit, Damien ULg

Doctoral thesis (2016)

To study the regularity of functions, many functional spaces have been introduced during the 20th century. Among them, let us mention the Hölder-Zygmund spaces \Lambda^{\alpha}(\R^{d}) and the Besov ... [more ▼]

To study the regularity of functions, many functional spaces have been introduced during the 20th century. Among them, let us mention the Hölder-Zygmund spaces \Lambda^{\alpha}(\R^{d}) and the Besov spaces B_{p,q}^{\alpha}(\R^{d}) where \alpha>0 somehow indicates the regularity of their elements (p,q\in ]0,+\infty]). The Hölder-Zygmund spaces are particular cases of Besov spaces in the sense that \Lambda^{\alpha}(\R^{d})=B_{\infty,\infty}^{\alpha}(\R^{d}). A generalization of Besov spaces has been introduced in the middle of the seventies and is still studied nowadays. This new type of space allows a deepest study of the regularity of functions. In this thesis, we start from this generalization in order to introduce a generalization of Hölder-Zygmund spaces. The first aim of this thesis is to show that most classical properties of Hölder-Zygmund spaces can be transposed to their generalized version. Among others, a complete characterization of these spaces in terms of wavelet coefficients is proved, which opens their use in the context of the signal analysis. The second aim of this thesis is to introduce a generalized version of the pointwise Hölder spaces similarly to their global version. We then show that most properties of the global spaces can be transposed to their generalized pointwise version. Finally, we study the regularity of some financial stochastic processes. [less ▲]

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See detailAssaying asparagine content in a complex matrix using a spectrophotometric method
Lecart, Brieuc ULg; Jacquet, Nicolas ULg; Anseeuw, Laurent et al

Poster (2016, June 23)

In this study we show, on 15 wheat varieties, the ability to assay the asparagine content in a complex matrix such as wheat flour by a simple spectrophotometric assay. This method is easier, faster and ... [more ▼]

In this study we show, on 15 wheat varieties, the ability to assay the asparagine content in a complex matrix such as wheat flour by a simple spectrophotometric assay. This method is easier, faster and cheaper than conventional chromatography analysis and allow to discriminate quickly which materials has high or low level of this amino acid. Asparagine is an amino acid present in free form in the food biomass and has the property of reacting with the free sugars during the Maillard reactions that occur during baking at temperatures above 120°C. The Acrylamide resulting from this reaction chain has been identified as reprotoxic, genotoxic and carcinogenic in animals since 1986. The present method allowed us to identify wheat varieties with significantly lower or higher asparagine contents (α=0.05). Therefore, this method can be used to identify wheat varieties or other plants with low asparagine content to use preferentially in products designed for food. [less ▲]

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See detailRole of the Ras-GTPase activating protein Rasa3 in Angiogenesis processes
Orban, Tanguy ULg

Poster (2016, June 22)

Rasa3 is a member of the Ras GAP1 subfamily and is known to function as dual GAP (GTPase activating protein) for Ras and Rap1 smallGTPases. Homologous knockout mice expressing a catalytically-inactive ... [more ▼]

Rasa3 is a member of the Ras GAP1 subfamily and is known to function as dual GAP (GTPase activating protein) for Ras and Rap1 smallGTPases. Homologous knockout mice expressing a catalytically-inactive Rasa3 protein die during embryonic life from massive bleedings due to destabilisation of endothelial junctions. The main goal of this project is to investigate and characterize the role of Rasa3 in angiogenesis which is the process by which new blood vessels develop from pre-existing ones. Here, we show that loss of function of Rasa3 in Huvecs (Human Umbilical Vein Endothelial Cells) affects their angiogenic potential. Interestingly, we found that inactivation of Rasa3 impacts migration/adhesion-related properties of endothelial cells. Using phase contrast microscopy and TIRF technology we showed that Rasa3 inactivation doesn’t affect cell directionality and that the stronger adhesion of cells on fibronectin is due to a downregulation of adhesion turnover. We showed that these alterations can be attributed to the hyperactivation of the smallGTPase Rap1 and downregulation of FAK/SRC signalling. We suggest that in the absence of Rap1, hyperactivation of FAK/SRC following integrin engagement could explain the different phenotypes observed. Altogether these preliminary results suggested a critical function of Rasa3 in angiogenesis. [less ▲]

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See detailThe role of autobiographical knowledge in episodic future thinking
D'Argembeau, Arnaud ULg

Conference (2016, June 22)

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See detailDix ans de ``Maths à Modeler à Liège'' ou comment un enseignant/chercheur s'invite dans des classes du secondaire
Rigo, Michel ULg

Conference given outside the academic context (2016)

Les missions d'un professeur d'université sont multiples : recherche, enseignement mais aussi citoyenneté. Depuis une dizaine d'années, je réalise de multiples activités de sensibilisation aux ... [more ▼]

Les missions d'un professeur d'université sont multiples : recherche, enseignement mais aussi citoyenneté. Depuis une dizaine d'années, je réalise de multiples activités de sensibilisation aux mathématiques : exposés, activités ludiques en petits groupes, etc. En répondant modestement à la question : "les maths ça sert à quoi ?", le but recherché est de démontrer l'utilité souvent méconnue des mathématiques, et de la recherche dans ce domaine (Google, réseaux sociaux, jeux vidéos, magie, etc.). Dans cette présentation, je dresserai tout d'abord l'historique du projet et tenterai d'analyser les actions menées. Ensuite, l'auditoire assistera à un tour de mathémagie et participera, de façon interactive, à un jeu démontrant l'importance du concept de preuve en mathématique. Ces jeux sont tirés de "Situations-Recherche pour la classe" développées par des chercheurs grenoblois. Enfin, j'expliquerai comment des étudiants de l'ULg (bacheliers, masters, étudiants à l'agrégation) et des doctorants participent à cette action. [less ▲]

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See detailInsect pathogenic Aspergillus species in mosquito (Diptera: Culicidae) control compared to Metarhizium anisopliae
Bawin, Thomas ULg

Doctoral thesis (2016)

Many mosquito (Diptera: Culicidae) species are vectors responsible for the transmission of infectious diseases of medical and veterinary importance. Risk for infection considerably increased during the ... [more ▼]

Many mosquito (Diptera: Culicidae) species are vectors responsible for the transmission of infectious diseases of medical and veterinary importance. Risk for infection considerably increased during the last decades due to climate changes and increasing global trade. Vector control is essential for public health management. Integrated pest management is now promoted due to harmful side effects of the chemical insecticides classically used for mosquito control and insect resistance development. This PhD thesis takes part in the selection process of insect pathogenic fungi. Three biological models (Aspergillus clavatus Desmazieres, Aspergillus flavus Link, and Metarhizium anisopliae (Metschnikoff) Sorokin) were selected and investigated regarding their spore insecticidal activity, mode of action, and selectivity. Throughout this scheme, the use of agricultural materials and derivatives in fermentation processes was emphasized. Production methods and insecticidal potential of the fungi were first investigated. On the one hand, the two Aspergillus species were compared to M. anisopliae regarding their spore production when cultured on agro-industrial substrates (white rice and wheat bran) and their insecticidal effect on larvae of the southern house mosquito, Culex quinquefasciatus Say. Our results showed that both substrates are suitable to culture the three insect pathogenic fungal species; but wheat bran-based media increased from 3 to 7-fold the spore yields in solid-state compared to white rice-based media. Also, insect pathogenic Aspergillus species were suggested to yield in similar spore levels in such conditions (in a range of 10^9 spores per g of substrate) and be as virulent against mosquito larvae compared to M. anisopliae. On the other hand, a bioreactor design intended to support large-scale production on agricultural materials by combining the technological advantages of submerged and solid-state fermentations was implemented using A. clavatus. This system allowed facility in recuperation and purification of spores (confined on a packed solid substrate) that retained virulence against mosquito larvae; but also metabolites (contained in a circulating liquid medium) that showed insecticidal effect. The mechanisms responsible for the insecticidal effects of the spores, and their selectivity were then investigated. On the one hand, the invasion routes of A. clavatus spores on mosquito larvae were investigated by light and electron microscopy. Histological observations suggest that toxins secreted by active germinating spores of A. clavatus in the digestive tract altered the larval tissues, leading to necrosis and causing larval death. Fungal proliferation and sporulation then occurred during a saprophytic phase. Such action mode also probably occurred in the case of the two other species. On the other hand, the insecticidal activity of the fungi was assessed against the pea aphid, Acyrthosiphon pisum Linnaeus. Adult A. pisum aphids were susceptible (increased mortality and decreased reproductive potential) to the three fungal species. As a consequence, these fungi would probably be able to infect a broad spectrum of insect hosts (whatever terrestrial or aquatic) once released in the environment. The implications of the results for mosquito control and application strategies are finally discussed, and perspectives for future works proposed. [less ▲]

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See detailUsing phytostabilisation as a way to conserve threatened endemic species from the Southeastern D.R. Congo
Boisson, Sylvain ULg; Le Stradic, Soizig ULg; Seleck, Maxime ULg et al

Conference (2016, June 22)

Metalliferous outcrops of the southeastern Democratic Republic of Congo are recognized as some of the largest copper-cobalt deposits of the world. They support unique vegetation with around 600 ... [more ▼]

Metalliferous outcrops of the southeastern Democratic Republic of Congo are recognized as some of the largest copper-cobalt deposits of the world. They support unique vegetation with around 600 metallophyte species including rare and endemic species. Since 1900s, the exploitation of the Cu-Co outcrops in D.R. Congo has considerably increased, impacting environment and putting public health at risk. Phytostabilisation is a suitable technology to decrease the bioavailability of heavy metals in highly polluted soils. This technic has been successfully implemented in the vicinity of Lubumbashi with the grass Microchloa altera. The long term maintenance of such technic requires a good understanding of the interspecific relationship like competition and facilitation. This study aims to test the success of establishment of four herbaceous species from the southeastern DRC presenting conservation priority and to assess the potential role of M. altera as nurse plant in this context. Two annual species and two perennial species were sown in experimental design with soil amendments crossed with vegetation cover. The emergence, the growth and the survival were followed during the vegetation season and the resprout was measured for perennial species. M. altera had a distinct effect on the emergence and the survival of the annual and perennial species but affected negatively the growth of individuals for all species. [less ▲]

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See detailAnatomie chirurgicale du plancher Pelvien et du rétropéritoine chez la femme
Bonnet, Pierre ULg

Conference (2016, June 22)

Leçon introductive reprenant les notions anatomiques essentielles à maîtriser lors de l'approche chirurgicale du pelvis et du rétropéritoine chez la femme. Approche constructive par la réalisation ... [more ▼]

Leçon introductive reprenant les notions anatomiques essentielles à maîtriser lors de l'approche chirurgicale du pelvis et du rétropéritoine chez la femme. Approche constructive par la réalisation extemporanée de schémas projetés. [less ▲]

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See detailImpact of cooking and species on intestinal fermentation patterns of vegetables in a humanized in vitro model of the gastro-intestinal tract
Kalala Bolokango, Gaetan ULg; Kambashi Mutiaka, Bienvenu ULg; Njeumen Lemotio, Georges Patrick ULg et al

Poster (2016, June 21)

Obesity and associated pathologies have dramatic consequences on patients’lives as well as high societal costs. Because of the role of intestinal dysbiosis and microbiota make-up on the pathogenesis of ... [more ▼]

Obesity and associated pathologies have dramatic consequences on patients’lives as well as high societal costs. Because of the role of intestinal dysbiosis and microbiota make-up on the pathogenesis of obesity, several strategies such as eating prebiotics and dietary fibre supplements are being investigated to reshape the intestinal microbial communities of obese patients. Beyond supplement, dietary fibre is supplied through plant ingredients in the meals. In the framework of the multidisciplinary research project Food4Gut, the use of vegetables rich in specific targeted dietary fiber, namely fructans, is being scrutinized for its ability to induce positive changes in the intestinal ecophysiology. Because expected effect might differ according the content in dietary fibre and fructans, the soluble:insoluble ratio, as well as the cooking of the vegetables, the fermentation patterns of several vegetables are being investigated in an dual in vitro model combining enzymatic hydrolysis to an in vitro fermentation step using faecal inoculums from humans, to evaluate the performance of gut microbiota, modulation of metabolic functions. Six vegetables were sampled in triplicates (N=3) and steamed for 20 to 30 min.: Jerusalem artichoke, salsify, asparagus, pumpkin, fennel and swede. They were chosen because they display a variety of contents in fructans, soluble (SDF) and insoluble dietaryfibre (IDF). Steamed vegetable samplesand burgers from local fast food restaurants (negative control) were hydrolyzed in vitro why porcine pepsin and pancreatin to mimic digestion in the upper gut and indigested fiber residues were recover using a 6kDa dialysis membrane.Subsequently, in vitro fermentation is being run with independent fecal inoculums from obese and lean patients (N=4). Fermentation kinetics over 24h as well as short-chain fatty acid production and profiles will be compared according to the individual donor and the vegetable species and multivariate analysis will be used to explore the relationships between donor, vegetable species and composition and fermentation patterns. [less ▲]

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See detailForest Inventory with Terrestrial LiDAR: A Comparison of Static and Hand-Held Mobile Laser Scanning
Bauwens, Sébastien ULg; Bartholomeus, Harm; Calders, Kim et al

in Forests (2016), 7(6), 127

The application of static terrestrial laser scanning (TLS) in forest inventories is becoming more effective. Nevertheless, the occlusion effect is still limiting the processing efficiency to extract ... [more ▼]

The application of static terrestrial laser scanning (TLS) in forest inventories is becoming more effective. Nevertheless, the occlusion effect is still limiting the processing efficiency to extract forest attributes. The use of a mobile laser scanner (MLS) would reduce this occlusion. In this study, we assessed and compared a hand-held mobile laser scanner (HMLS) with two TLS approaches (single scan: SS, and multi scan: MS) for the estimation of several forest parameters in a wide range of forest types and structures. We found that SS is competitive to extract the ground surface of forest plots, while MS gives the best result to describe the upper part of the canopy. The whole cross-section at 1.3 m height is scanned for 91% of the trees (DBH > 10 cm) with the HMLS leading to the best results for DBH estimates (bias of 0.08 cm and RMSE of 1.11 cm), compared to no fully-scanned trees for SS and 42% fully-scanned trees for MS. Irregularities, such as bark roughness and non-circular cross-section may explain the negative bias encountered for all of the scanning approaches. The success of using MLS in forests will allow for 3D structure acquisition on a larger scale and in a time-efficient manner. [less ▲]

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See detailDesign criteria and experimental performance - Extended end-plate
Demonceau, Jean-François ULg

Conference (2016, June 21)

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See detailCryopreservation of cyanobacteria in the BCCM/ULC collection: experimental set-up of protocols
Crahay, Charlotte ULg; Renard, Marine ULg; Day, John G et al

Conference (2016, June 21)

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See detailNatural radioactivity and elemental composition of sands in the Douala region, Littoral of Cameroon Using Portable XRF and HPGe detector
Guembou Shouop, Cébastien Joel ULg; Ndontchueng Moyo, Maurice; Chene, Grégoire ULg et al

Poster (2016, June 21)

Twenty four sand samples from seven sand quarries alone the Gulf of Guinea, Douala Littoral region of Cameroon, were analyzed using high purity germanium detector and a portable X-ray fluorescence (PXRF ... [more ▼]

Twenty four sand samples from seven sand quarries alone the Gulf of Guinea, Douala Littoral region of Cameroon, were analyzed using high purity germanium detector and a portable X-ray fluorescence (PXRF) spectrometer. A comprehensive study was conducted to determine the natural radioactivity concentrations and the geological provenience of sand samples from seven different quarries sites of the Douala, a popular city, and its surroundings. The radioactivity investigation was performed by using high resolution gamma-ray spectrometry. From the measured gamma-spectra, the average activity concentrations were determined for 226Ra, 232Th, 40K and 235U for a depth of 5–25 cm. Results of this study were compared to values from other locations around the world. X-ray fluorescence spectrometry (XRF) measurements were performed for the quantitative elemental analysis of the sands, revealing the major, minor and trace elements present in the investigated samples. Reference marine and geological sample are used to check precision and accuracy of the equipment for major and minor components. From XRF experimental results it was possible to estimate the geological provenience of the analyzed sands. These data record the radioactivity background levels in sands and could be used as reference information in Cameroon. The comparison of major (Si, Al), minor (K, Ca,Fe), and trace (Ti, Mn, Zr, Rb, Sr) element ratios was made. The results indicate that the levels of Si and Al can be very helpful in subgroup definition and provide useful clues to the raw materials used for glassmaking in Cameroon. [less ▲]

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See detailRéinventer son enseignement : Pourquoi ? Comment ?
Poumay, Marianne ULg

Conference (2016, June 21)

Detailed reference viewed: 46 (4 ULg)
See detailQu'est-ce qu'une approche par les capacités ?
Orianne, Jean-François ULg

Conference given outside the academic context (2016)

Detailed reference viewed: 18 (1 ULg)
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See detailOrganic Rankine cycle modelling and the ORCmKit library: analysis of R1234ze(Z) as drop-in replacement of R245fa for low-grade waste heat recovery
Ziviani, Davide; Dickes, Rémi ULg; Quoilin, Sylvain ULg et al

in Proceedings of ECOS 2016 (2016, June 20)

Due to the wide interest in organic Rankine cycles (ORCs) as a sustainable technology and the importance of numerical analyses and optimization procedures while considering such systems, we created a ... [more ▼]

Due to the wide interest in organic Rankine cycles (ORCs) as a sustainable technology and the importance of numerical analyses and optimization procedures while considering such systems, we created a dedicated open-source library named “ORC modelling Kit” (ORCmKit). The comprehensive library includes single com-ponents and overall models for subcritical, transcritical and supercritical ORCs. Three main programming environments are currently supported: Matlab, Python and EES (Engineering Equation Solver). A detailed steady-state cycle model of a small-scale regenerative ORC with a single-screw expander is used to evalu-ate the performance influence of R1234ze(Z) as a drop-in replacement of R245fa currently used in the instal-lation. The ORC system is used to recover low-grade waste heat with a temperature range between 90°C and 120°C. A thermal oil heater is used to simulate the heat source. A parametric study is carried out to in-vestigate the performance of the system throughout the range of interest in order to optimize the ORC with R1234ze(Z). [less ▲]

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See detailCdk1 is a critical mediator of ischemic/hypoxic neuronal death
Vandenbosch, Renaud ULg

Conference (2016, June 20)

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Peer Reviewed
See detailUsing herbarium records to explore the ecological differentiation between closely‐related tree species in tropical Africa
Gorel, Anaïs ULg; Duminil; Doucet, Jean-Louis ULg et al

Poster (2016, June 20)

Background: Tree hypothesis are invoked to explain species distribution and evolutionary history of tree clades in tropical Africa: 1) The forest refuge hypothesis postulates that contractions of lowland ... [more ▼]

Background: Tree hypothesis are invoked to explain species distribution and evolutionary history of tree clades in tropical Africa: 1) The forest refuge hypothesis postulates that contractions of lowland forests during the climatic oscillations of the Pleistocene could have driven allopatric speciation between fragmented populations; 2) The ecological gradient hypothesis states that environmental gradients promote parapatric speciation; 3) The vanishing refuge hypothesis reconciles the two previous hypotheses and postulated a diversification process through climate-driven habitat fragmentation and exposure to new environments. Disentangling the respective influence of environmental and historical factors requires information on phylogeny, as well as information on geography and the environmental space used by species. In this study, we aimed to determine the environmental factors constraining the distribution of African tree species in order to explore ecological divergence and speciation processes. Method: We focused on three African Erythrophleum species (Fabaceae, Caesalpinioideae) that are economically and socially important, providing timber and non-timber resources. Erythrophleum ivorense, Erythrophleum suaveolens and Erythrophleum africanum also show contrasted distributions in Africa. To determine species climatic niche, we used a combination of species presence data gathered from 606 herbarium records and environmental factors (19 BIOCLIM variables). We used Species Distribution Models (SDM, MaxEnt algorithm) in combination with similarity metrics to quantify the degree of niche divergence between species. Results: We showed that the distribution of Erythrophleum species are substantially determined by climate (especially annual rainfall and temperature range) and support the ecological gradient hypothesis. Moreover, the main traits (e.g. wood density and leaf area) and growth rates previously reported among Erythrophleum species confirmed a differential adaptation to drought. Conclusion: Herbarium data provide valuable information on the distribution of species over the whole range. In tropical regions where extensive inventories data are extremely rare, herbarium records in combination with presence-only SDM offer opportunities to explore speciation processes. [less ▲]

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