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See detailThe CCAMBIO project to characterize the biodiversity and distribution of microorganisms in microbial mats of Antarctic lakes
Durieu, Benoit ULg; Lara, Yannick ULg; Obbels, Dagmar et al

Poster (2016, April 29)

The BelSPO project CCAMBIO aims to study the biogeographical distribution of microorganisms in lacustrine microbial mats using a combination of techniques including microscopical observations (light and ... [more ▼]

The BelSPO project CCAMBIO aims to study the biogeographical distribution of microorganisms in lacustrine microbial mats using a combination of techniques including microscopical observations (light and electronic microscopy), strain isolation, and molecular diversity assessment using Next Generation Sequencing. The samples were collected in different Antarctic and sub-Antarctic biogeographical regions. A detailed microscopic study of the Antarctic diatom diversity allowed to revise a number of taxa and discover new ones. A multivariate analysis of diatoms showed that these regions hosted different diatom flora. Endemic diatom taxa were also observed, and a multigene molecular phylogeny of Pinnularia borealis showed a high genetic diversity. Pilot studies were conducted for the microeukaryotes and cyanobacteria to select NGS protocols and bioinformatic pipelines. Preliminary multivariate analysis of over 100 samples revealed that distinct biogeographic zones could be recognized in both the prokaryote and eukaryote data, which is in agreement with the classical subdivision of the Antarctic Realm into Maritime Antarctica, Continental Antarctica and the Sub-Antarctic Islands generally observed in plants and animals. Moreover, Sub-Antarctic assemblages harboured more complex foodwebs, with quite diverse metazoan groups. Lakes on the continent, however, were characterised by fewer metazoan groups and a greater importance of microbial herbivores and secondary consumers, including a relative high diversity of ciliates and tardigrades. Variation partitioning analysis revealed that spatial variables that approximated large-scale regional contrasts in historical (e.g. deglaciation history, geological origin) and climatic factors (e.g. mean annual air temperature) significantly explained the largest portion of the observed variation in community structure for eukaryotes, while in the prokaryote data environmental gradients related to conductivity were more important. In a first analysis of microbial mats from five Antarctic lakes and an aquatic biofilm from the Sub-Antarctic, the majority of the cyanobacterial OTUs retrieved were related to filamentous taxa such as Leptolyngbya and Phormidium, which are common genera in Antarctic lacustrine microbial mats. However, other phylotypes related to different taxa such as Geitlerinema, Pseudanabaena, Synechococcus, Chamaesiphon, Calothrix and Coleodesmium were also found. Results revealed a higher diversity than what had been reported using traditional methods based on microscopic observations and cultivation and also highlighted remarkable differences between the cyanobacterial communities of the studied lakes. In the next months, the molecular diversity data will be deposited into the “Microbial Antarctic Resource System (MARS)” presently developed into the webportal ‘biodiversity.aq’. The better knowledge of the diversity and distribution of microorganisms will contribute to a better assessment of their resilience and local/regional responses to global change. [less ▲]

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See detailElucidating diversity of thin filamentous mat-forming Antarctic cyanobacteria
Lara, Yannick ULg; Durieu, Benoit ULg; Deblander, Victor ULg et al

Poster (2016, April 29)

Freshwater ecosystems range from glacial cryoecosystems, ice shelf meltwater ponds to perennially ice-covered lakes where conspicuous benthic microbial mat communities constitute most of the biomass. In ... [more ▼]

Freshwater ecosystems range from glacial cryoecosystems, ice shelf meltwater ponds to perennially ice-covered lakes where conspicuous benthic microbial mat communities constitute most of the biomass. In these mats, cyanobacteria form matrices that shelter other organisms, and carry out the primary production. Narrow filamentous cyanobacteria belonging to the genera Leptolyngbya and Phormidium are especially abundant in Antarctic microbial mats and are essential for the formation of matrix. However, the lack of morphological criteria and the small cell size of cyanobacteria belonging to these two genera make their identification problematic. Indeed, they are known as polyphyletic taxa according to botanical and bacteriological criteria. The characterization of strains is the first step for an assessment of the real diversity and for understanding their role in the environment. We designed a polyphasic approach that combines molecular analyses, environmental physiology experiments and microscopic observations. Briefly, we amplified and sequenced three loci (16S rRNA, ITS, and rpoC1) for 31 strains of Leptolyngbya and Phormidium. We performed whole genome sequencing for five strains. Cultures at different stage were observed by light and epifluorescence microscopy. Finally, selected strains were grown in nitrogen-limited. The Leptolyngbya and Phormidium strains were distributed into four lineages. Phylogenetic trees supported the distribution of P. priestleyi strains into at least two potentially new lineages, and L. antarctica strains were separated into one endemic and one cosmopolitan lineage. This was supported by the microscopic observations of 1-year old cultures. Genome analyses revealed the presence of sequences related to the production of secondary metabolites in strains from two of the studied lineages. Secondary metabolites are often known for their antimicrobial activities. Such properties would partly explain how cyanobacterial mats survive to predation and degradation by other bacteria. This work provides the first building block to the understanding of survival strategies developed by mat-forming cyanobacteria and how they succeeded as the most abundant phototrophs on the Antarctic continent. This work was realized in the frame of the BelSPo project CCAMBIO. [less ▲]

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See detailModeling in Air Transportation: Cargo Loading and Itinerary Choice
Lurkin, Virginie ULg

Doctoral thesis (2016)

We examine two problems as part of this dissertation. The first is a cargo loading problem. The aim is to load a set of containers and pallets into a cargo aircraft that serves multiple airports. Our work ... [more ▼]

We examine two problems as part of this dissertation. The first is a cargo loading problem. The aim is to load a set of containers and pallets into a cargo aircraft that serves multiple airports. Our work is the first to model cargo transport as a series of trips consisting of several legs at the end of which pickup and delivery operations might occur. This problem is crucial for airlines because in an attempt to reduce their costs, most airlines prefer to load as many containers as possible, even if all the loaded containers do not have the same final destination. Our results demonstrate that it is possible to quickly find near optimal or excellent feasible loading plans, and that our approach leads to substantial savings with respect to typical manual approaches currently used in practice. The second problem we examine involves the estimation of itinerary choice models that include price variables and correct for price endogeneity using a control function that uses several types of instrumental variables. The motivation for developing these models is to demonstrate the importance of accounting for price endogeneity and to estimate different price sensitivities as a function of advance purchase periods. This is important as the airline industry can use our results to incorporate different customer segments as revealed through high-yield and low-yield booking curves when evaluating the profitability of airline schedules. Results based on Continental U.S. markets for May 2013 departures showed that models that fail to account for price endogeneity overestimate customers' value of time and result in biased price estimates and incorrect pricing recommendations. The advanced models estimated (nested logit and ordered generalized extreme value (OGEV) models) are shown to outperform the baseline multinomial logit model with regard to statistical tests and behavioral interpretations. Additionally, results show that price sensitivities vary as a function of advance purchase periods, with those purchasing high-yield products being less price sensitive than those purchasing low-yield products (across any advance purchase periods) and those purchasing closer to departure being less price sensitive. Results also indicate that inter-alternative competition is strong for itineraries that share similar departure times. Finally, as part of the itinerary choice model developed in this dissertation, we estimate highly refined departure time of day preferences. Results are intuitive and show that departure time of day preferences vary across many dimensions including the length of haul, direction of travel, number of time zones crossed, departure day of week, and itinerary type (i.e., outbound, inbound, and one-way itineraries). To the best of our knowledge, these curves represent the most refined publicly-available estimates of airline passengers' time of day preferences. [less ▲]

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See detailYearbook 2015 Ateliers d'Architecture III: Logement collectif durable et conception régénérative
Attia, Shady ULg

Book published by SBD Lab, Liege University - 1 (2016)

C’est en Wallonie que la naissance de la seconde révolution industrielle a débuté. La Wallonie est une terre d’innovation. Dans ce contexte, c’est le lieu de création comme le béton de chanvre, les ... [more ▼]

C’est en Wallonie que la naissance de la seconde révolution industrielle a débuté. La Wallonie est une terre d’innovation. Dans ce contexte, c’est le lieu de création comme le béton de chanvre, les briques d’argiles, les panneaux photovoltaïques en acier, les panneaux de paille préfabriqués etc.,… Dans le contexte de lutte contre le changement climatique, du développement durable et d’économie circulaire, les ingénieurs architectes s’allient afin de réinventer une architecture responsable économiquement et écologiquement. Les activités de l’atelier 2014 se concevaient comme une synergie entre les apports théoriques inter disciplinaires, l’expérimentation complète de durabilité régénérative, la construction circulaire et leur intégration dans un projet architecturale. Grâce à un engagement remarquable des étudiants de l’atelier de SBD Lab (Sustainable Buildings Design Lab) et à l’apport enrichissants d’intervenants de multiples disciplines, les résultats obtenus durant cette année 2014 ont complété les prévisions faites pour un site à Liège. D’un point de vue architectural, la multiplicité et l’originalité de solutions proposées par les étudiants nourrissent les réflexions en cours à l’échelle de la ville de Liège et les questions relatives aux conditions de densification et renouveau urbain. D’un point de vue didactique, cette démarche exigeante a favorisé l’émergence chez chaque étudiant d’un savoir structuré tant au niveau conceptuel que pratique. [less ▲]

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See detailSensitivity of turbulent Schmidt number and turbulence model to simulations of jets in crossflow
Valero Huerta, Daniel ULg; Bung, Daniel B

in Environmental Modelling & Software (2016), 82

Environmental discharges have been traditionally designed by means of cost-intensive and timeconsuming experimental studies. Some extensively validated models based on an integral approach have been often ... [more ▼]

Environmental discharges have been traditionally designed by means of cost-intensive and timeconsuming experimental studies. Some extensively validated models based on an integral approach have been often employed for water quality problems, as recommended by USEPA (i.e.: CORMIX). In this study, FLOW-3D is employed for a full 3D RANS modelling of two turbulent jet-to-crossflow cases, including free surface jet impingement. Results are compared to both physical modelling and CORMIX to better assess model performance. Turbulence measurements have been collected for a better understanding of turbulent diffusion's parameter sensitivity. Although both studied models are generally able to reproduce jet trajectory, jet separation downstream of the impingement has been reproduced only by RANS modelling. Additionally, concentrations are better reproduced by FLOW-3D when the proper turbulent Schmidt number is used. This study provides a recommendation on the selection of the turbulence model and the turbulent Schmidt number for future outfall structures design studies. [less ▲]

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See detailOptical flow estimation in aerated flows
Bung, Daniel B.; Valero Huerta, Daniel ULg

in Journal of Hydraulic Research (2016)

Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents ... [more ▼]

Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn–Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn–Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150. [less ▲]

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See detailLa critique génétique dans la collection "Poétique"
Lorent, Fanny ULg

Conference (2016, April 29)

La critique génétique est, comme le dit bien Jean-Louis Jeannelle, une « théorie en quête d’elle-même » , tiraillée entre la tradition philologique et les avancées structuralistes. Elle doit sans cesse, à ... [more ▼]

La critique génétique est, comme le dit bien Jean-Louis Jeannelle, une « théorie en quête d’elle-même » , tiraillée entre la tradition philologique et les avancées structuralistes. Elle doit sans cesse, à la fois, se défaire des suspicions positivistes qui pèsent sur elle et justifier son appartenance possible à la (une ?) poétique . Nous voudrions étudier, dans cette communication, les mécanismes de légitimation de cette discipline aux contours épistémologiques complexes au sein même de la collection « Poétique », qui accueillit, en 1998, Les brouillons de soi de Philippe Lejeune et, en 2011, Logiques du brouillon de Daniel Ferrer. Comment les auteurs vont-ils, dans leur ouvrage, justifier leur parution au sein d’une collection dont les présupposés théoriques semblent, a priori, contraires à ceux présidant à leur travail ? Quelles en sont alors les implications méthodologiques, pour chacune des deux disciplines ? [less ▲]

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See detailLe droit du travail (re)visité par la Cour constitutionnelle
Kéfer, Fabienne ULg

in Boufflette, Sophie (Ed.) La cour constitutionnelle. De l'art de modeler de droit pour préserver l'égalité (2016, April 29)

L'étude porte sur le rôle de la Cour constitutionnelle dans l’édification du droit du travail. Arrêt après arrêt, elle consolide la norme attaquée ou au contraire redessine – ou presse le législateur de ... [more ▼]

L'étude porte sur le rôle de la Cour constitutionnelle dans l’édification du droit du travail. Arrêt après arrêt, elle consolide la norme attaquée ou au contraire redessine – ou presse le législateur de redessiner – les contours de cette branche du droit fortement marquée par son histoire. Elle se penche sur un peu plus de trente arrêts prononcés par la Cour constitutionnelle, principalement depuis 2008, dans les domaines suivants : le travail à temps partiel (chapitre 1), le droit de la non-discrimination (chapitre 2), certaines questions intéressant le licenciement, à savoir la durée du préavis, les mesures destinées à stimuler l’employabilité, la motivation, la notion de rémunération en cours en cas de réduction temporaire des prestations de travail, et l’indemnité d’éviction du représentant de commerce (chapitres 3 à 7), les distinctions entre employés et ouvriers autres que les conditions de licenciement (chapitre 8), la procédure de réorganisation judiciaire (chapitre 9) et la prescription (chapitre 10). [less ▲]

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See detailCognition et imagination. Réflexions à partir de Mach, Musil et Wittgenstein
Zincq, Aurélien ULg

Conference (2016, April 29)

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See detailCrop residue management in arable cropping systems under temperate climate. Part 1: Soil biological and chemical (phosphorus and nitrogen) properties. A review
Lemtiri, Aboulkacem ULg; Degrune, Florine ULg; Barbieux, Sophie ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment (2016)

Interacting soil organisms support biological processes that participate in soil functions, organic matter decomposition, and nutrient cycling. Earthworms and microorganisms play a range of beneficial ... [more ▼]

Interacting soil organisms support biological processes that participate in soil functions, organic matter decomposition, and nutrient cycling. Earthworms and microorganisms play a range of beneficial roles in agricultural systems, including increased organic matter mineralization, nutrient cycling, and soil structure stabilization. The following aspects of crop residue management effects are examined in this paper: (i) earthworm composition and structure; (ii) soil microbial communities; and (iii) phosphorus (P) and nitrogen (N) element availability and distribution in the soil profile. Conventional tillage (ploughing) is often reported to generate decreased soil organism abundance and diversity, primarily earthworms and microorganisms, as well as a uniform distribution of the nutrients P and N within the ploughed soil horizon. Soil residue incorporation of mineral particles can maintain P and N levels, however returning soil also increases aeration and the activation of microbial activity. Hence, comparisons of tillage effects on soil biological functioning and nutrient cycling remain unclear. This review highlights the challenges in establishing definitive evidence regarding the effects of crop residue management on soil organisms and nutrient dynamics. The studies examined reported variability in soil and climate, and the complexity of soil processes contributed to the absence of clear findings. Further research is required under temperate climate conditions. [less ▲]

Detailed reference viewed: 56 (6 ULg)
See detailThe origin of eukaryotes is linked to the rooting of the Tree of Life... but the phylogenetic jury is still out!
Gouy, Richard ULg

Scientific conference (2016, April 28)

The origin of the eukaryotes remains one of the most contentious puzzles in evolution. In the late 1970s, C. Woese discovered Archaea and put an end to the dichotomous view of Life (eukaryote vs ... [more ▼]

The origin of the eukaryotes remains one of the most contentious puzzles in evolution. In the late 1970s, C. Woese discovered Archaea and put an end to the dichotomous view of Life (eukaryote vs prokaryote). Since Woese’s revolution, the Tree of Life (ToL) has been divided into three domains (Bacteria, Archaea and Eukaryota), yet with unclear relationships. Rooting the ToL then became a problem. Indeed, the question of the origin of eukaryotes is directly related to the location of this root, which also affects the nature of the Last Universal Common Ancestor (LUCA). Several scenarios might explain the origin of the eukaryotic cell: (a) the three domains have an independent origin and directly stemmed from the primordial soup; (b) the three domains stemmed from a simple LUCA, and their evolution proceeded by increasing complexity in eukaryotes; (c) the three domains stemmed from a complex LUCA, and their evolution proceeded by simplification in prokaryotes; (d) eukaryotes originated from a fusion event between an archaeon and a bacterium, the latter being the mitochondrion and their other properties evolving after this event; (e) eukaryotes originated from a fusion event between an archaeon and a bacterium, the result being a proto-eukaryote not yet equipped with a mitochondrion. During the last 15 years, technical advances in phylogenetic methods have relocated many simple organisms higher in the ToL, which means that they are actually secondary simplified. However, even the best evolutionary models are not yet able to address difficult phylogenetic issues, whether at shallow depth or at deep evolutionary times. This raises a fundamental question: does simple always mean ancestral? For the time being, the commonly accepted bacterial root for the ToL (in scenario (b)) is still unproven, so that the current consensus can be traced back to the prejudice of Aristotle’s Great Chain of Beings, in which simple organisms are ancestors of more complex life forms. Indeed, during early evolution, there might have been many independently arising lineages, both before and along LUCA, none of them having left extant descendants. The major bottlenecks that occurred as a result of catastrophic events in Earth’s history (e.g., meteorite impacts or snowball Earth periods) might explain why we only have three domains of Life nowadays. Furthermore, extant lineages coalesce to a LUCA that was not necessarily simple and located at the base of the ToL. Instead, it probably lived much later and was more complex than generally acknowledged. [less ▲]

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See detailLe Non Bis In Idem en droit de la concurrence: un monde de différence avec le pénal?
Van Cleynenbreugel, Pieter ULg

Scientific conference (2016, April 28)

At this colloquium, I analysed the specific interpretation given to the non bis in idem principle in EU competition law. I compared the Court's case law in this domain with the case law of the European ... [more ▼]

At this colloquium, I analysed the specific interpretation given to the non bis in idem principle in EU competition law. I compared the Court's case law in this domain with the case law of the European Court of Human Rights and the Court itself in other domains and questioned to what extent a competition law exceptionalism could still be tolerated. [less ▲]

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See detailWhat do selectorates seek? A comparative analysis of Belgian federal and regional candidate selection processes in 2014
Vandeleene, Audrey; Dodeigne, Jérémy ULg; De Winter, Lieven

in American Behavioral Scientist (2016), 60(7), 889-908

The 2014 “mother of all elections” in Belgium offers a unique opportunity to test whether candidate selection for regional and federal elections work alike or differently. The fact that Belgian ... [more ▼]

The 2014 “mother of all elections” in Belgium offers a unique opportunity to test whether candidate selection for regional and federal elections work alike or differently. The fact that Belgian “statewide” parties do not exist anymore and that Belgium is a quasi-closed list system, giving parties almost unlimited control over candidate selection enhances the uniqueness of the Belgian case. This article verifies whether these “regional” parties select candidates according to different methods for both elections and whether candidates for both elections display different attributes. Our exploratory analysis draws on in-depth interviews with party actors, on the 2014 Belgian Candidate Survey and on an extensive database of regional and federal parliamentary/executive careers since 1991. Our results show that selection procedures strongly differ across parties but hardly within parties regarding regional and federal elections. Besides, regarding candidates’ attributes, only few differences were found between levels. Hence, both levels seem to work alike. [less ▲]

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See detailCOP21 and Electrical Systems
Ernst, Damien ULg

Speech/Talk (2016)

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See detailSexual attraction in lady beetles: fundamentals and applications
Fassotte, Bérénice ULg

Doctoral thesis (2016)

Sustainable agriculture relies on the development of environmentally friendly methods of crop production. Therefore, alternative solutions are required to decrease insecticide use and to promote the ... [more ▼]

Sustainable agriculture relies on the development of environmentally friendly methods of crop production. Therefore, alternative solutions are required to decrease insecticide use and to promote the efficacy of natural enemies against insect pests. Investigating the sexual behavior of lady beetles is of practical relevance, because these insects could be used to reduce plant-feeding insect populations in crop fields by taking advantage of their predatory behavior. In this context, the objective of this PhD thesis was twofold: (1) a fundamental research that focuses on the identification of the sex pheromone of Harmonia axyridis (Pallas) and (2) an applied approach aimed at elaborating semiochemicals slow-release dispensers with these compounds, in order to attract individuals in cultivated fields. We have demonstrated that virgin females of H. axyridis display a typical male-calling behavior in presence of prey, which is associated with the release of a pheromonal blend that is highly attractive for conspecific males. Dynamic headspace sampling and subsequent chemical analyses allowed the characterization of this sex pheromone. Finally, we focused on the development of a formulation releasing a combination of semiochemicals that attract aphid predators. The formulation, composed of alginate beads, was optimized under laboratory conditions. The release rate of the formulation was assessed by dynamic headspace sampling coupled with adsorbent trapping. The formulation was efficient at attracting two natural enemies of aphids. All these results are discussed in the context of sustainable agriculture, with the use of semiochemicals, and especially pheromones, as potential tools to enhance current cropping systems. In near future, the application of such molecules, based on strong knowledge of insect olfaction, is expected to increase considerably with the development of new methods aimed at attracting predators and/or parasitoids. In addition, improvements of experimental devices, such as the elaboration of slow release dispensers, are suggested in the last chapter of this PhD thesis. [less ▲]

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See detailTerrorisme, flux médiatique et petits chatons. De quelques narrations de l'invisible.
Hamers, Jérémy ULg

Scientific conference (2016, April 28)

Partant de quelques événements terroristes récents (Paris 2015, Verviers 2015, Bruxelles 2016), cette conférence une analyse critique des multiples réactions médiatiques que ces événements ont suscité en ... [more ▼]

Partant de quelques événements terroristes récents (Paris 2015, Verviers 2015, Bruxelles 2016), cette conférence une analyse critique des multiples réactions médiatiques que ces événements ont suscité en télévision comme sur internet. Editions spéciales de journaux télévisés, enquêtes d'amateurs sur des sites dédiés aux théories du complot, détournements d'images sur les réseaux sociaux seront abordés ici comme autant de narrations qui, malgré leur hétérogénéité, répondent toutes à l'invisibilité partielle et momentanée de l'acte terroriste au moment où il surgit dans le paysage médiatique. [less ▲]

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See detailLa Paix de Fexhe. Qui ? Quoi ? Comment ? Pourquoi ?
Masson, Christophe ULg

Conference given outside the academic context (2016)

Detailed reference viewed: 23 (2 ULg)