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See detailRetirement age and the age of onset of Alzheimer’s disease: Results from the ICTUS study
Grotz, Catherine ULg; Letenneur, Luc; Bonsang, Eric ULg et al

in PLoS ONE (2015)

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See detailPropagation of uncertainties using probabilistic multi-scale models
Lucas, Vincent ULg; Wu, Ling ULg; Paquay, Stéphane et al

Conference (2015, February 25)

When applying a multiscale approach, the material behavior at the macro-scale can be obtained from an homogenization scheme. To this end, at each integration-point of the macro-structure, the macrostress ... [more ▼]

When applying a multiscale approach, the material behavior at the macro-scale can be obtained from an homogenization scheme. To this end, at each integration-point of the macro-structure, the macrostress tensor is related to the macro-strain tensor through the resolution of a micro-scale boundary value problem. At the micro-level, the macro-point is viewed as the center of a Representative Volume Element (RVE). However, to be representative, the micro-volume-element should have a size much bigger than the micro-structure size. When considering structures of reduced sizes, such as micro-electro-mechanical systems (MEMS), as the size of the devices is only one or two orders of magnitude higher than the size of their microstructure, i.e. their grain size, the structural properties exhibit a scatter at the macro-scale. The representativity of the micro-scale volume element is lost and Statistical Volume Elements (SVE) should be considered in order to account for the micro-structural uncertainties. These uncertainties should then be propagated to the macro-scale in order to predict the device properties in a probabilistic way. In this work we propose a non-deterministic multi-scale approach [1] for poly-silicon MEMS resonators. A set of SVEs is first generated under the form of Voronoi tessellations with a random orientation assigned for each silicon grain of each SVE. The resolution of each micro-scale boundary problem is performed by recourse to the computational homogenization framework, e.g. [2], leading to meso-scale material properties under the form of a linear material tensor for each SVE. Applying a Monte-Carlo procedure allows a distribution of this material tensor to be determined at the meso-scale. The correlation between the meso-scale material tensors of two SVEs separated by a given distance can also be evaluated. A generator of the meso-scale material tensor is then implemented using the spectral method [3]. The generator [1] accounts for a lower bound [4] of the meso-scale material tensor in order to ensure the existence of the second-order moment of the Frobenius norm of the tensor inverse [5]. A macro-scale finite element model of the beam resonator can now be achieved using regular finite-element, i.e. not conforming with the grains, and the material tensor at each Gauss point is obtained using the meso-scale generator, which accounts for the spatial correlation. A Monte-Carlo method is then used at the macro-scale to predict the probabilistic behavior of the MEMS resonator. As an example the beam resonator illustrated in Fig. 1(a) is made of poly-silicon, and each grain has a random orientation. Solving the problem with a full direct numerical simulation combined to a Monte-Carlo method allows the probability density function to be computed as illustrated in Fig. 1(b). However this methodology is computationally expensive due to the number of degrees of freedom required to study one sample. The proposed non-deterministic multi-scale strategy allows reducing this computational cost as the Monte-Carlo processes are applied on much smaller finite-element models. The method can also be applied in the context of fracture of thin poly-silicon film [6]. In this case, a set of meso-scopic cohesive laws can be obtained at the meso-scale from the resolution of different SVEs. The meso-scopic cohesive laws are obtained for each RVE from the finite element resolution of the Voronoi tessellations using the method proposed in [7]. The resulting statistical values for the critical energy release rate and for the critical strength can then be used for macro-scale simulations. [less ▲]

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See detail7. Lutte intégrée contre les ravageurs - 2.1 Suivi des populations de cécidomyie équestre, Haplodiplosis marginata, grâce au développement d'un piège à phéromone
Censier, Florence ULg; Fischer, Christophe ULg; Chavalle, Sandrine et al

in Watillon, Bernard; Bodson, Bernard (Eds.) Livre Blanc Céréales (2015, February 25)

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See detailProtection of Antarctic microbial communities–‘out of sight, out of mind’
Hughes, Kevin; Cowan, Don; Wilmotte, Annick ULg

in Frontiers in Microbiology (2015), 6(151), 1-6

RecentadvancesinmolecularbiologytechniqueshaveshownthepresenceofdiversemicrobialcommunitiesandendemicspeciesinAntarctica.Endemicmicrobesmaybeapotentialsourceofnovelbiotechnologicallyimportantcompounds ... [more ▼]

RecentadvancesinmolecularbiologytechniqueshaveshownthepresenceofdiversemicrobialcommunitiesandendemicspeciesinAntarctica.Endemicmicrobesmaybeapotentialsourceofnovelbiotechnologicallyimportantcompounds,including,forexample,newantibiotics.Thus,thescientificandbiotechnologicalvalueofAntarcticterrestrialmicrobialhabitatscanbecompromisedbyhumanvisitationtoagreaterextentthanpreviouslyrealized.Theever-increasinghumanfootprintinAntarcticamakesconsiderationofthistopicmorepressing,asthenumberoflocationsknowntobepristinehabitats,whereincreasinglysophisticatedcutting-edgeresearchtechniquesmaybeusedtotheirfullpotential,declines.ExaminationoftheProtectedAreassystemoftheAntarcticTreatyshowsthatmicrobialhabitatsaregenerallypoorlyprotected.NoothercontinentonEarthisdominatedtothesamedegreebymicrobialspecies,andrealopportunitiesexisttodevelopnewwaysofconceptualizingandimplementingconservationofmicrobialbiogeographyonacontinentalscale.Herewehighlightpotentialthreatsbothtotheconservationofterrestrialmicrobialecosystems,andtofuturescientificresearchrequiringtheirstudy. [less ▲]

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See detail10. Perspectives - 1. La Lutte contre les pucerons grâce aux odeurs: développement d'une formulation phéromonale
Fassotte, Bérénice ULg; Vandereycken, Axel ULg; Chevalier Mendes Lopes, Thomas ULg et al

in Watillon, Bernard; Bodson, Bernard (Eds.) Livre Blanc Céréales (2015, February 25)

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See detailPoly(vinyl ester 1,2,3-triazolium)s: a new member of the poly(ionic liquid)s family
Obadia, M. M.; Colliat-Dangus, G.; Debuigne, Antoine ULg et al

in Chemical Communications (2015), 51(16), 3332-3335

A vinyl ester monomer carrying a pendant 1,2,3-triazole group is synthesized in two steps and polymerized by cobalt-mediated radical polymerization. Subsequent alkylation with N-methyl bis ... [more ▼]

A vinyl ester monomer carrying a pendant 1,2,3-triazole group is synthesized in two steps and polymerized by cobalt-mediated radical polymerization. Subsequent alkylation with N-methyl bis[(trifluoromethyl)sulfonyl]imide affords the corresponding poly(vinyl ester 1,2,3-triazolium). This unprecedented example of poly(vinyl ester ionic liquid) exhibits an ionic conductivity of 9.2 × 10(-7) S cm(-1) at 30 °C [less ▲]

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See detailQuantifying landscape anthropisation patterns: concepts, methods and limits
Vranken, Isabelle ULg

Doctoral thesis (2015)

Since human beings began to use and shape the land, their influence on their environment has kept on growing so that little or no ecosystem in the world is now considered as untouched. This induces ... [more ▼]

Since human beings began to use and shape the land, their influence on their environment has kept on growing so that little or no ecosystem in the world is now considered as untouched. This induces pressures on ecosystem health and land scarcity. Africa is of particular concern because it still presents broad undisturbed zones and key ecosystem services, despite being submitted to increasing anthropogenic pressures. Landscape ecology appears suitable for the study of such phenomena, thanks to its spacebased integrative nature and geographical level of focus. It studies the impact of spatial pattern transformation — especially heterogeneity and its components — on ecological processes and provides powerful analytical tools of landscape anthropisation. The main objective of this thesis is to organise the concepts and methods, from landscape ecology and related disciplines, into a consistent logic, to pinpoint missing analytical frameworks for response-oriented anthropisation assessment, and to apply them to African cases to explore the spatial patterns of anthropisation. In order to address landscape anthropisation, we assemble diverse disciplines into a logical network (DPSIR). The new theoretical framework is tested on Lubumbashi (DRC). In order to address spatial patterns, we first evaluate the thermodynamic connection of the term entropy in landscape ecology: spatial heterogeneity, unpredictability and scale influence. Then, based on 20 landscapes, we highlight the complex relationship between spatial heterogeneity and landscape anthropisation. We finally use the modelled relationships to test the anthropogenic origin of the spatial pattern of a land cover class in Lubumbashi. The main results of this research show that several concepts are used to describe different aspects of anthropisation and that its quantification strongly depends on the reference states. Data formats can be combined into a new assessment method ensuring more precision and comparability, but a good field knowledge is required. As for heterogeneity, the existing definitions of landscape entropy follow the logic of thermodynamics or information theory, that are not compatible. Only unpredictability could be properly interpreted in thermodynamic terms if energy transfer measurements were performed at the appropriate level. The anthropogenic effects on heterogeneity completely diverge depending on the amount of already anthropised surface, on the land cover type (natural or anthropogenic), and on the heterogeneity components. The aforementioned findings could be adapted to include functional aspects and better address the relationship between spatial pattern and ecological processes. Such integration would help designing response actions that can recommend human activities and spatial patterns that could optimise the use of land to ensure ecological functioning while supporting human development. [less ▲]

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See detailContribution à l’étude de la dynamique de l’élevage pastoral au Niger : cas de la région de Diffa
Laouali, Abdoulkadri ULg

Doctoral thesis (2015)

In the Sahelian countries where extensive pastoral breeding is practiced, livestock plays an essential role in the socio-economic and dietary balance of the households. However, throughout the literature ... [more ▼]

In the Sahelian countries where extensive pastoral breeding is practiced, livestock plays an essential role in the socio-economic and dietary balance of the households. However, throughout the literature, this activity was submitted to various controversies including its contribution to the degradation of the environment; greenhouse gas emissions; its weak economic performance; etc. But other studies have noted the importance and efficiency of pastoral practice in a precarious natural environment such as the Republic of Niger, great stockbreeding country in the heart of the Sahel, with a herd of over 37 million heads. Thus, this research has tried to reposition the debate by emphasizing the role and importance of pastoral breeding in the Sahelian countries in general, particularly in Niger and specifically in the region of Diffa. Located between the desert zone in the North and the Sahelian zone in the South, the Region of Diffa is a pastoral area par excellence in Niger. Breeding, with a highly diversified livestock, is the dominant economic activity in the region. It concerns 95% of the population and contributes annually to 55% of the regional gross domestic product. However, this activity is submitted to various constraints, particularly biophysical and anthropogenic. In order to understand the pastoral dynamics in this region, a research work was initiated starting in 2010 and following a systemic approach. The work was built around three poles: Man-Natural Resources-Animals. A survey of 300 households (150 households with a sedentary herd and 150 with a mobile herd) was conducted during the first semester of 2012. Investigations were made on the basis of the prior identification of three agro-ecological zones (pastoral bowls, Komadougou River, Lake Chad) based on 100 households for each zone. The research results revealed that pastoral breeding in the region of Diffa is mutating. Herds (sedentary and mobile) are relatively small sized and increasingly composed in majority by small ruminants. The reproduction is carried out by a core of female spawners more or less stable and dominated by younger ones. Data cross analysis highlights the occurrence of recurrent fodder deficits, attributable to a series of annual rainfall deficits as well as animal diseases as the main causes of changing pastoral breeding in the region of Diffa. To deal with these problems the pastoral and agro-pastoral populations have built and developed a set of adaptive strategies to resist shocks and to mitigate their effects and to ensure the survival of households and livestock. However, over the years and the recurrence of shocks, traditional strategies for managing risks and uncertainties are being weakened with socio-economic consequences in pastoral and agro-pastoral households. An Intervention of the State, NGOs and / or associations and other development partners, would boost these strategies and strengthen the capacity of households to manage risk in the long term. [less ▲]

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See detailCover Songs Retrieval and Identification
Osmalsky, Julien ULg

Conference (2015, February 24)

Cover songs retrieval is a MIR task that has been widely studied in the recent years. The task, in its general sense, consists in retrieving covers for a given audio query. In this PhD, we focus on the ... [more ▼]

Cover songs retrieval is a MIR task that has been widely studied in the recent years. The task, in its general sense, consists in retrieving covers for a given audio query. In this PhD, we focus on the more specific task of cover songs *identification*. Given an unknown cover song query, we want to find relevant information about the original song, such as the title, the artist etc. Applications are live music recognition, plagiarism detections, query by examples, etc. Our approach is based on a pruning algorithm, whose role is to discard as quickly as possible as many tracks as possible from a search database in order to keep a smaller subset that should contain the tracks relevant to the query. We introduce the concept of *rejectors* for the pruning algorithm, which are single or combined classifier using multiple audio features for selecting relevant tracks. [less ▲]

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See detailResonant and antiresonant bouncing droplets
Hubert, Maxime ULg; Robert, Damien; Caps, Hervé ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015), 91

When placed onto a vibrating liquid bath, a droplet may adopt a permanent bouncing behavior, depending on both the forcing frequency and the forcing amplitude. The relationship between the droplet ... [more ▼]

When placed onto a vibrating liquid bath, a droplet may adopt a permanent bouncing behavior, depending on both the forcing frequency and the forcing amplitude. The relationship between the droplet deformations and the bouncing mechanism is studied experimentally and theoretically through an asymmetric and dissipative bouncing spring model. Antiresonance phenomena are evidenced. Experiments and theoretical predictions show that both resonance at specific frequencies and antiresonance at Rayleigh frequencies play crucial roles in the bouncing mechanism. In particular, we show that they could be exploited for bouncing droplet size selection. [less ▲]

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See detailTwo-Photon Luminescence of Gold Nanorods Mediated by Higher Order Plasmon Modes
Verellen, Niels; Denkova, Denitza; De Clercq, Ben et al

in ACS Photonics (2015), 2

Metallic nanorod antennas can be considered as an analogue to classical half-wave dipole antennas, constituting an important tool for manipulating linear and nonlinear lightmatter interactions in ... [more ▼]

Metallic nanorod antennas can be considered as an analogue to classical half-wave dipole antennas, constituting an important tool for manipulating linear and nonlinear lightmatter interactions in nanoscale volumes. Using two-photon luminescence (TPL) scanning laser microscopy, we investigate such optical antennas beyond their fundamental dipole mode. The antenna mode dispersion is extracted from the nonlinear TPL measurement and reveals a TPL process that is dominated by plasmon-induced enhancement of the two photon absorption in the metal. Additionally, a clear signature of the mode parity is observed in the TPL images. TPL maxima are observed outside the antenna boundaries for even parity modes, whereas they are located inside for odd modes. It is concluded that for even modes the two-photon luminescence emission is strongly mediated by retardation of the excitation field, a consequence of their zero net-dipole moment. This selective excitation of different mode parities is highly relevant for nanoscale enhanced nonlinear optics, as well as plasmonic nanosensor applications and tuning of radiative properties of quantum emitters. [less ▲]

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See detailInorhanic and organic carbon spatial variability in the Congo River during high waters (December 2013) and low waters (June 2014)
Borges, Alberto ULg; Bouillon, S; Teodoru, C et al

Conference (2015, February 23)

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See detailBiologie du développement (partim. animal)
Peers, Bernard ULg

Learning material (2015)

Detailed reference viewed: 14 (1 ULg)
See detailMédiations numériques de la lecture
Barnabé, Fanny ULg

Scientific conference (2015, February 23)

Séance de séminaire sur la médiation que représente le numérique dans la lecture littéraire.

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See detailSolidarities and Learning: Reporting Incidents in a Nuclear Research Center
Rossignol, Nicolas ULg

Scientific conference (2015, February 23)

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See detailLes plantes qui nous soignent : de la tradition à la médecine moderne
Frederich, Michel ULg

Scientific conference (2015, February 23)

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See detailEMODnet regional gridded abundance products: a tool to facilitate ecosystem assessments
Beckers, Jean-Marie ULg

Scientific conference (2015, February 20)

Detailed reference viewed: 5 (0 ULg)
See detailFAO Training in Crop Yield Forecasting - Remote Sensing - Method for Crop Yield Forecasting System (CYFS) from spatial Remote Sensing for Tajikistan. Integration of PROBA-V NDVI images. Belgium - Arlon Campus Environment - January 2015.
Denis, Antoine ULg

Learning material (2015)

This manual has been written for the “Training for strengthening crop yield forecasting capacity of the State Administration for Hydrometeorology (Hydromet) of Tajikistan” that occurred between 12nd ... [more ▼]

This manual has been written for the “Training for strengthening crop yield forecasting capacity of the State Administration for Hydrometeorology (Hydromet) of Tajikistan” that occurred between 12nd January and 7th February 2015 in Arlon – Belgium in the framework of the Food and Agriculture Organization (FAO) of the United Nations Project (GCP/TAJ/007/EC) “Support to Strengthening the National Food Security Information System in Tajikistan”. This manual is intended to cover the Remote Sensing part only of the general Crop Yield Forecasting System (CYFS). Despite written for the Tajik context this manual can serve as an example for all other countries. This manual follows on from the 2 manuals entitled: 1) “FAO Training in Crop Yield Forecasting ARMENIA - Erevan – May 2011 – Remote Sensing”. 2) “FAO Training in Crop Yield Forecasting. Improvement of the Crop Yield Forecasting System (CYFS) in Armenia: a new approach for satellite data integration. ARMENIA - Yerevan - January 2013.” This manual, in addition to adapt the method to Tajik context, integrates for the first time the NDVI images of PROBA-V satellite. These images continue the stopped SPOT-VEGETATION time’s series, from 2014 to undefined future. [less ▲]

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See detailThe Airline Container Loading Problem with Pickup and Delivery
Lurkin, Virginie ULg; Schyns, Michael ULg

in European Journal of Operational Research (2015)

This paper considers the loading optimization problem for a set of containers and pallets transported into a cargo aircraft that serves multiple airports. Because of pickup and delivery operations that ... [more ▼]

This paper considers the loading optimization problem for a set of containers and pallets transported into a cargo aircraft that serves multiple airports. Because of pickup and delivery operations that occur at intermediate airports, this problem is simultaneously a Weight & Balance Problem and a Sequencing Problem. Our objective is to minimize fuel and handling operation costs. This problem is shown to be NP-hard. We resort to a mixed integer linear program. Based on real-world data from a professional partner (TNT Airways), we perform numerical experiments using a standard B&C library. This approach yields better solutions than traditional manual planning, which results in substantial cost savings. [less ▲]

Detailed reference viewed: 153 (54 ULg)