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See detailObjectif Mars
Stiepen, Arnaud ULg

Conference given outside the academic context (2017)

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See detailAssessing microbial diversity changes associated with different tillage and crop residue managements: study case in a loamy soil
Degrune, Florine ULg

Doctoral thesis (2017)

The major challenge of modern agriculture is to produce enough food for the growing population, and at the same time, minimize environmental harm. To meet this challenge, Agroecology aims to replace non ... [more ▼]

The major challenge of modern agriculture is to produce enough food for the growing population, and at the same time, minimize environmental harm. To meet this challenge, Agroecology aims to replace non-renewable external inputs with ecological processes to diversify the ecosystem services and attenuate the dis-services of agriculture. In this light, the ability to manage the soil microbiota, that has great effects on soil quality, is receiving attention. Plowing, the most widely used tillage practice in intensive agriculture has proven its efficiency in maximizing crop productivity, but its long term detrimental effects on soil quality, such as soil erosion and organic matter loss, have called for alternative tillage practices. However, the success of the implementation of these practices in Europe is still debated. In the upper part of Wallonia (Belgium), the soil is highly fertile and 80% of land is occupied mostly by intensive cropping systems. To date in Walloon cropping systems, few studies have explored the soil microbiota in association with different soil managements. Here, we used a meta-barcoding approach to explore differences in soil microbial community structure under two contrasting tillage regimes, conventional (CT) and reduced tillage (RT), either with or without crop residue retention. The effects of these soil treatments were explored at different depths and during the growing season of two crops. Our work demonstrated clear differences in microbial diversity between tillage regimes, but no clear differences between residue management practices. The observed differences appeared to be associated with differences in physical (e.g. structure and moisture) and chemical (nutrients) soil properties. Notably, the nutrient concentrations and moisture were higher under CT than under RT. Overall, soil under CT had higher or similar microbial diversity than under RT. Analysis of β-diversity revealed differences in the taxonomic structure of microbial communities. Certain microbial groups were more abundant under CT than under RT and vice versa. For example, mycorrhizal fungi, economically and ecologically important in agroecosystems, were more abundant under RT. Finally, the magnitude of tillage effects on the microbial diversity varied strongly with the sampling depth, whereas it varied moderately with the growing season. This work highlighted CT was not necessarily unfavourable in maintaining microbial diversity when compared to RT. However, the study raises new questions regarding the impacts of microbial diversity changes on soil functioning. We encourage researchers to undertake further investigations into the functional role of microbiota in order to improve our understanding of agroecosystem functioning and its sustainability. [less ▲]

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See detailEnquête sur les pratiques de pâturage en Wallonie: Résultats et conclusions
Lessire, Françoise ULg; Dufrasne, Isabelle ULg

Conference given outside the academic context (2017)

The role of grasslands as a C sink is generally accepted. It is considered that permanent grasslands allow annual C storage rates between 22 and 44 g C/m2/y (Soussana et al., 2010) thereby contributing to ... [more ▼]

The role of grasslands as a C sink is generally accepted. It is considered that permanent grasslands allow annual C storage rates between 22 and 44 g C/m2/y (Soussana et al., 2010) thereby contributing to the mitigation of greenhouse gas (GHG) emissions. Grassland preservation has several other advantages including a decrease in feeding costs (Dillon et al., 2005), a positive effect on cows’ health (e.g.a decrease in lameness) (Burow et al., 2011) and the provision of a positive image to consumers. Despite these arguments, grazing is decreasing in Europe and grasslands are disappearing. A better understanding of grazing practices and of farmers’ expectations could suggest ways of improving these practices and limiting grassland disappearance. As a result, Walloon dairy farmers were surveyed in December 2015 and the preliminary results are presented below. [less ▲]

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Peer Reviewed
See detailStatistics of localized phase slips in tunable width planar point contacts
Baumans, Xavier ULg

in Scientific Reports (2017), 7

The main dissipation mechanism in superconducting nanowires arises from phase slips. Thus far, most of the studies focus on long nanowires where coexisting events appear randomly along the nanowire. In ... [more ▼]

The main dissipation mechanism in superconducting nanowires arises from phase slips. Thus far, most of the studies focus on long nanowires where coexisting events appear randomly along the nanowire. In the present work we investigate highly confined phase slips at the contact point of two superconducting leads. Profiting from the high current crowding at this spot, we are able to shrink in-situ the nanoconstriction. This procedure allows us to investigate, in the very same sample, thermally activated phase slips and the probability density function of the switching current I sw needed to trigger an avalanche of events. Furthermore, for an applied current larger than I sw , we unveil the existence of two distinct thermal regimes. One corresponding to efficient heat removal where the constriction and bath temperatures remain close to each other, and another one in which the constriction temperature can be substantially larger than the bath temperature leading to the formation of a hot spot. Considering that the switching current distribution depends on the exact thermal properties of the sample, the identification of different thermal regimes is of utmost importance for properly interpreting the dissipation mechanisms in narrow point contacts. [less ▲]

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See detailApproche psychocriminologique du processus de radicalisation chez les adolescents
Garcet, Serge ULg

Conference given outside the academic context (2017)

Le processus de radicalisation à l’adolescence est le reflet d’un déterminisme réciproque entre les influences des pairs et un questionnement identitaire. La communication vise à expliquer comment cette ... [more ▼]

Le processus de radicalisation à l’adolescence est le reflet d’un déterminisme réciproque entre les influences des pairs et un questionnement identitaire. La communication vise à expliquer comment cette interaction influence la représentation du monde et le sens que lui donne l’adolescent. La compréhension de ces mécanismes cognitifs est sans doute une des clés pour comprendre ce phénomène et tenter de lui apporter une réponse. [less ▲]

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See detailCancer in the organ donor
DETRY, Olivier ULg

Conference (2017, March 16)

Organ Donation and Cancer Pr Olivier Detry, Dpt of Abdominal Surgery and Transplantation, University of Liege The risk of transmission of cancer with the transplanted organ has been known since the ... [more ▼]

Organ Donation and Cancer Pr Olivier Detry, Dpt of Abdominal Surgery and Transplantation, University of Liege The risk of transmission of cancer with the transplanted organ has been known since the pioneering years of solid organ transplantation, and is enhanced by immunosuppression and particularly the calcineurin inhibitors. Therefore, classically, potential organ donors with past history of cancer are excluded from donation, with the exception of low-grade malignant tumours of the central nervous system, the skin and the cervix uteri. Despite that policy, every year, some cases of cancer transmission with organ transplantation were regularly reported in transplant medical journals. At the other hand, there is a clear graft shortage, with long organ transplant waiting lists and inacceptable mortality while waiting for a life saving graft. One mean to increase the number of available grafts could be to accept donation from donors with past history of cancer. Several uncertainties remain: what is the risk of cancer transmission with organ transplantation? This risk depends of course of many donor factors, as the staging and the nature of the donor malignant tumour, the oncological management, the delay between the remission and the organ procurement. This risk may also vary according to the type of organ transplanted, as livers and lungs are more prone to bear occult metastases, compared to the hearts for example. In fact, this risk is unknown, and was clearly overestimated by the old registries as the IPTR, and by the various case reports. All modern prospective registries, as from UNOS or from UK transplant, now report a very low rate of cancer transmission when the donor cancer was known and evaluated before organ donation. Undiagnosed or occult cancer transmission with transplantation is clearly another issue that should not be mistaken with the donors with past history of cancer. In most of the recent reported cases of cancer transmission with transplantation, the donor cancer was not diagnosed before and during organ donation. And this risk increases in modern organ transplantation, as we are now accepting older and older donors, particularly in transplantation of the liver, an organ particularly at risk of metastases. Therefore surgical donor exploration is an important step of organ procurement. Body CT could be a tool to diagnose some, but not all, of these tumours. To my view, the risk of cancer transmission with transplantation has to be balanced with the risk of dying on the waiting lists. Donors with active or recent aggressive cancers have to be excluded from donation. Some types of aggressive cancers, as lymphoma or melanoma, are at high risk. In donors with past history of cancer with some years of remission, organ donation should be considered for recipients at high risk of death without a rapid transplantation. Particularly, heart transplantation, an organ with a low risk of cancer transmission but with a severe organ shortage, could benefit from such a policy. [less ▲]

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See detailReconnaissance en psychiatrie légale
Englebert, Jérôme ULg

Scientific conference (2017, March 15)

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See detailOffline Policy-search in Bayesian Reinforcement Learning
Castronovo, Michaël ULg

Doctoral thesis (2017)

This thesis presents research contributions in the study field of Bayesian Reinforcement Learning — a subfield of Reinforcement Learning where, even though the dynamics of the system are un- known, the ... [more ▼]

This thesis presents research contributions in the study field of Bayesian Reinforcement Learning — a subfield of Reinforcement Learning where, even though the dynamics of the system are un- known, the existence of some prior knowledge is assumed in the form of a distribution over Markov decision processes. In this thesis, two algorithms are presented: OPPS (Offline Prior- based Policy Search) and ANN-BRL (Artificial Neural Networks for Bayesian Reinforcement Learning), whose philosophy consists to analyse and exploit the knowledge available beforehand prior to interacting with the system(s), and which differ by the nature of the model they make use of. The former makes use of formula-based agents introduced by Maes et al. in (Maes, Wehenkel, and Ernst, 2012), while the latter relies on Artificial Neural Networks built via SAMME (Stagewise Additive Modelling using a Multi-class Exponential loss function) — an AdaBoost algorithm developed by Zhu et al. in (Zhu et al., 2009). Moreover, we also describe a comprehensive benchmark which has been created to compare Bayesian Reinforcement Learning algo- rithms. In real life applications, the choice of the best agent to fulfil a given task depends not only on their performances, but also on the computation times required to deploy them. This benchmark has been designed to identify the best algorithms by taking both criteria into account, and resulted in the development of an open-source library: BBRL (Benchmarking tools for Bayesian Reinforcement Learning) (https://github.com/mcastron/BBRL/wiki). [less ▲]

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See detailModelling of organic Rankine cycle power systems in off-design conditions: an experimentally-validated comparative study
Dickes, Rémi ULg; Dumont, Olivier ULg; Daccord, Rémi et al

in Energy (2017), 123

Because of environmental issues and the depletion of fossil fuels, the world energy sector is undergoing many changes toward increased sustainability. Among the many fields of research and development ... [more ▼]

Because of environmental issues and the depletion of fossil fuels, the world energy sector is undergoing many changes toward increased sustainability. Among the many fields of research and development, power generation from low-grade heat sources is gaining interest and the organic Rankine cycle (ORC) is seen as one of the most promising technologies for such applications. In this paper, it is proposed to perform an experimentally-validated comparison of different modelling methods for the off-design simulation of ORC-based power systems. To this end, three types of modelling paradigms (namely a constant-efficiency method, a polynomial-based method and a semi-empirical method) are compared both in terms of their fitting and extrapolation capabilities. Post-processed measurements gathered on two experimental ORC facilities are used as reference for the models calibration and evaluation. The study is first applied at a component level (i.e. each component is analysed individually) and then extended to the characterization of the entire organic Rankine cycle power systems. Benefits and limi- tations of each modelling method are discussed. The results show that semi-empirical models are the most reliable for simulating the off-design working conditions of ORC systems, while constant-efficiency and polynomial-based models are both demonstrating lack of accuracy and/or robustness. [less ▲]

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See detailA random walk in Machine Learning
Begon, Jean-Michel ULg

Conference given outside the academic context (2017)

Since the dawn of machine learning (ML), it hasn’t stop spreading into our everyday lives in new, creative ways. Why Google, Facebook, Amazon and the like have invested so much in ML recently? What can ... [more ▼]

Since the dawn of machine learning (ML), it hasn’t stop spreading into our everyday lives in new, creative ways. Why Google, Facebook, Amazon and the like have invested so much in ML recently? What can (and can’t) ML actually do for us? In this non-technical (and non-exhaustive) talk we will examine ML applications ranging from standard uses to some of the most exotic ones. [less ▲]

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Peer Reviewed
See detailEnolates in macromolecular science: current situation and future outlook
Lecomte, Philippe ULg; Jérôme, Christine ULg

in Zabicky, Jacob (Ed.) The Chemistry of Metal Enolates (Volume 2) (2017)

Detailed reference viewed: 31 (5 ULg)
See detailHieroglyphic encoding & hieroglyphic sign-lists. From the Ramses Project to the Thot Sign-List
Polis, Stéphane ULg

Scientific conference (2017, March 14)

Based on systematic observations regarding the encoding of hieroglyphs in an electronic corpus, specifically the Ramses corpus (ramses.ulg.ac.be), the aim of this presentation was to introduce and discuss ... [more ▼]

Based on systematic observations regarding the encoding of hieroglyphs in an electronic corpus, specifically the Ramses corpus (ramses.ulg.ac.be), the aim of this presentation was to introduce and discuss the data-model of the Thot Sign-List (under development at the university of Liège) and to present online resources made available for documenting the elements of this model (http://thot.philo.ulg.ac.be/index.html). Among the future goals is a strengthened collaboration between the AKU project and the Thot Sign-List (e.g., a shared hieroglyphic sign-list and a connection between the graphemes analysed by the AKU project and the texts of Ramses Online). [less ▲]

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See detailLa réalisation et les complications de la césarienne dans la race Blanc-bleu Belge
Djebala, Salem ULg; Casalta, Hélène ULg; Rao, Anne-Sophie ULg et al

Conference given outside the academic context (2017)

La césarienne est la chirurgie la plus couramment réalisée en Belgique. Bien que celle-ci soit une intervention de routine le taux de complications post-opératoires est non négligeable. Deux enquêtes ont ... [more ▼]

La césarienne est la chirurgie la plus couramment réalisée en Belgique. Bien que celle-ci soit une intervention de routine le taux de complications post-opératoires est non négligeable. Deux enquêtes ont été réalisées au près des éleveurs et des vétérinaires sur la préparation, le déroulement de la césarienne et les soins post-opératoires. Ces deux enquêtes nous ont permis de tirer des conclusions et formuler des recommandations afin de réduire le taux de complication. [less ▲]

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See detailEvaluation de la fonction rénale
DELANAYE, Pierre ULg

Conference (2017, March 14)

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See detailApport de l'ENMG aux syndromes douloureux diffus
WANG, François-Charles ULg

Scientific conference (2017, March 14)

Detailed reference viewed: 14 (1 ULg)
See detailFormation and characterization of artificial lipid bilayers on optical fibers
Toussaint, Pauline ULg; Dreesen, Laurent ULg

Conference (2017, March 14)

Transports across cellular membranes are at the basis of a lot of biological processes such as the transmission of information in neurons. Their characterization is therefore of crucial interest. As they ... [more ▼]

Transports across cellular membranes are at the basis of a lot of biological processes such as the transmission of information in neurons. Their characterization is therefore of crucial interest. As they are equivalent to biological membranes, artificial lipid bilayers can be created to study membranes and transmembrane proteins properties or transmembrane transports. The aim of this work is to develop a new method for the fabrication of artificial membranes based on the use of optical fibers as support for the bilayer, and for their characterization by fluorescence measurements. We use microfluidics on fibers to create two phospholipid monolayers that we approach close enough to form a bilayer. The membrane formation is checked using fluorescein or a fluorescent sodium probe, Tetra (tetramethylammonium) salt (sodium green), whose optical signal depends on sodium concentration. [less ▲]

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See detailQSAR models and the flexible regulation of chemicals
Thoreau, François ULg

Scientific conference (2017, March 14)

Detailed reference viewed: 33 (0 ULg)