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See detailNotre cerveau reptilien
Scholtes, Félix ULg; Martin, Didier ULg

Scientific conference (2014, March 12)

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See detailOpen-source CAT software: R packages and Concerto
Magis, David ULg

Conference (2014, March 12)

Together with the investigation of new or updated CAT procedures, it is of primary importance to ensure development of appropriate, flexible and useful CAT software. Open-source CAT algorithms have been ... [more ▼]

Together with the investigation of new or updated CAT procedures, it is of primary importance to ensure development of appropriate, flexible and useful CAT software. Open-source CAT algorithms have been recently proposed and are offering very promising tools for future practical CAT implementations, though yet under development. After a brief overview of available (commercial) software, I will present and compare the characteristics of some open-source R packages as CAT solutions: catR (Magis, & Raîche, 2012), catIrt (Nydick, 2013) and MAT (Choi, 2011), as well as the R-based software Firestar (Choi, 2009). A more complete description of catR will be given and (depending on time and computer constraints) a short illustrative session will be proposed. Finally, the web platform Concerto (Kosinski & Rust, 2011) will be shortly introduced. References: Choi, S. W. (2009). Firestar: Computerized adaptive testing simulation program for polytomous item response theory models. Applied Psychological Measurement, 33, 644-645. Choi, S. W. (2011). MAT: Multidimensional Adaptive Testing (MAT). R package version 0.1-3. Kosinski, M., & Rust, J. (2011). The development of Concerto: An open source online adaptive testing platform. Paper presented at the International Association for Computerized Adaptive Testing, Pacific Grove, CA. Magis, D., & Raîche, G. (2012). Random generation of response patterns under computerized adaptive testing with the R package catR. Journal of Statistical Software, 48 (8), 1-31. Nydick, S. W. (2013). catIrt: An R package for simulating IRT-based computerized adaptive tests. R package version 0.4-1. [less ▲]

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See detailOndes de choc et tendinopathies : expérience clinique du CHU de Liège
Kaux, Jean-François ULg

Conference (2014, March 11)

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See detailOn the Identication of Symmetric N-qubit Maximally Entangled States
Baguette, Dorian ULg; Bastin, Thierry ULg; Martin, John ULg

Poster (2014, March 11)

Maximally entangled states can serve as a useful resource in many different contexts. It is therefore important to identify those states. Here we are interested in the identification of maximally ... [more ▼]

Maximally entangled states can serve as a useful resource in many different contexts. It is therefore important to identify those states. Here we are interested in the identification of maximally entangled states in the symmetric subspace of an N-qubit system. By maximally entangled states, we refer to symmetric states characterized by a one qubit reduced density matrix proportional to the identity. These states maximise various entanglement measures [1] such as von Neumann and Meyer-Wallach entropy and are unique up to LU in their SLOCC class [2]. We identify and characterize all maximally entangled symmetric states up to 4 qubits. We provide general conditions for a symmetric state with an arbitrary number of qubits to be maximally entangled and identify families of SLOCC classes which do not contain any maximally entangled states. [1] F. Verstraete, J. Dehaene, B. De Moor, Phys. Rev. A 68, 012103 (2003). [2] G. Gour, N. Wallach, N. J. Phys. 13, 073013 (2011) [less ▲]

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See detailMédias et acteurs économiques en Europe. De la crise du journalisme aux discours de crise
Geuens, Geoffrey ULg

Conference given outside the academic context (2014)

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Peer Reviewed
See detailBringing regenerating tissues to life: the importance of angiogenesis in tissue engineering
Carlier, Aurélie ULg; Van Gastel, Nick; Geris, Liesbet ULg et al

Poster (2014, March 11)

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See detailComputational homogenization of cellular materials capturing micro-buckling, macro-localization and size effects
Nguyen, Van Dung ULg

Doctoral thesis (2014)

The objective of this thesis is to develop an efficient multi-scale finite element framework to capture the macroscopic localization due to the micro-buckling of cell walls and the size effect phenomena ... [more ▼]

The objective of this thesis is to develop an efficient multi-scale finite element framework to capture the macroscopic localization due to the micro-buckling of cell walls and the size effect phenomena arising in structures made of cellular materials. Under the compression loading, the buckling phenomenon (so--called micro--buckling) of the slender components (cell walls, cell faces) of cellular solids can occur. Even if the tangent operator of the material of which the micro--structure is made, is still elliptic, the presence of the micro--buckling can lead to the loss of ellipticity of the resulting homogenized tangent operator. In that case, localization bands are formed and propagate in the macroscopic structure. Moreover, when considering a cellular structure whose dimensions are close to the cell size, the size effect phenomenon cannot be neglected since deformations are characterized by a strain gradient. On the one hand, a classical multi-scale computational homogenization scheme (so-called first-order scheme) looses accuracy with the apparition of the macroscopic localization or the high strain gradient arising in cellular materials because the underlying assumption of the local action principle, in which the stress state on a macroscopic material point depends only on the strain state at that point, is no--longer suitable. On the other hand, the second-order multi-scale computational homogenization scheme proposed by Kouznetsova exhibits a good ability to capture such phenomena. Thus this second--order scheme is improved in this thesis with the following novelties so that it can be used for cellular materials. First, at the microscopic scale, the periodic boundary condition is used because of its efficiency. As the meshes generated from cellular materials exhibit a large void part on the boundaries and are not conforming in general, the classical enforcement based on the matching nodes cannot be applied. A new method based on the polynomial interpolation without the requirement of the matching mesh condition on opposite boundaries of the representative volume element (RVE) is developed. Next, in order to solve the underlying macroscopic Mindlin strain gradient continuum of this second-order scheme by the displacement-based finite element framework, the presence of high order terms (related to the higher stress and strain) leads to many complications in the numerical treatment. Indeed, the resolution requires the continuities not only of the displacement field but also of its first derivatives. This work uses the discontinuous Galerkin (DG) method to weakly impose these continuities. This proposed second--order DG--based FE2 scheme appears to be easily integrated into conventional parallel finite element codes. Finally, the proposed second-order DG-based FE2 scheme is used to model cellular materials. As the instability phenomena are considered at both scales, the path following technique is adopted to solve both the macroscopic and microscopic problems. The micro--buckling leading to the macroscopic localization and the size effect phenomena can be captured within the proposed framework. [less ▲]

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See detailL'Homme de Spy, 125 ans plus tard
Flas, Damien ULg

Conference given outside the academic context (2014)

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See detailCorsican seagrass detritus: An opportune shelter or a copepod Eldorado?
Mascart, Thibaud ULg; Lepoint, Gilles ULg; Remy, François ULg et al

Poster (2014, March 07)

Seagrass ecosystems are extensive beds of marine flowering plants bordering tropical and temperate coastal regions. They play an important role in maintaining biological productivity and bio-geochemical ... [more ▼]

Seagrass ecosystems are extensive beds of marine flowering plants bordering tropical and temperate coastal regions. They play an important role in maintaining biological productivity and bio-geochemical cycles in the sea and support higher diversity and abundance of fauna in comparison to adjacent non-vegetated areas. The seagrass meadow primary production can be directly consumed through herbivory but the majority of the plant material falls on the sea floor during the autumnal leaf senescence. The leaf litter then degrades within the meadow or accumulates with other micro- and macrophytodetritus to form detritus accumulations on the adjacent non-vegetated sand patches. These exported accumulations are quite dynamic in relation to seafloor geomorphology and local hydrodynamics. Thus, the detritus accumulations are an easily disturbed ephemeral environment with one large influx a year. Consequently the physico-chemical characteristics can change very fast and impact the sheltering capacity and food supply present. Nonetheless, fishes, macrofauna and meiofauna are omnipresent throughout the year. In our study site along the shore of N-W Corsica, Posidonia oceanica seagrass meadows are characterised by substantial detritus accumulations. The present study aimed to analyse the biodiversity of the copepod species communities (Crustacea, Copepoda) in those detritus accumulations. The results showed that the copepod detritus community consisted of a mixture of species that are also found in adjacent habitats (seagrass meadow, sediment, epilithic habitats, water column). Each adjacent habitat is characterised by organisms that are morphologically adapted to the specific features of that habitat. The majority of copepods are epiphytic (order Harpacticoida), that occur typically on seagrass leaves and macroalgae. Other species are planktonic (orders Cyclopoida and Calanoida) and some were benthic (order Harpacticoida), known from the nearby sediment. A minority of the copepod community were parasitic on fish or invertebrate (order Siphonostomatoida). In order to clarify their origin, we assume that passive transport by currents plays a significant role next to the active migration from the anoxic sediments under the detritus. For sure they also reproduce within the detritus packages as we found many nauplii, copepodites and gravid females. The above mentioned suggestions cannot explain such high density of copepods by themselves. Other attraction mechanisms are needed to explain the important amount of planktonic and epiphytic species with good swimming ability, such as higher food accessibility. In the detritus no plant-defence mechanisms are present anymore and a lot of micro-organisms and thus potential food sources are present. Furthermore, the dense detritus package provides shelter and protection from potential predators. Subsequently we may consider the detritus accumulations as a copepod species-specific opportune Eldorado for sheltering, nursing and feeding. [less ▲]

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See detailA framework for using decision-support tools at various spatial scales for the management of irrigated agriculture in semi-arid West-Africa
Wellens, Joost ULg

Doctoral thesis (2014)

The Kou watershed, situated in the Southwestern part of Burkina Faso, has succumbed since a couple of decades to a typical theater play of anarchistic water management. With its 1.800 km², this small ... [more ▼]

The Kou watershed, situated in the Southwestern part of Burkina Faso, has succumbed since a couple of decades to a typical theater play of anarchistic water management. With its 1.800 km², this small watershed includes the second largest city of Burkina Faso (Bobo-Dioulasso), a former state run irrigated rice scheme and several informal agricultural zones. Despite the abundance of water resources, most water users find themselves regularly faced with shortages due to an increase in population and low irrigation efficiencies. Local stakeholders are hence in need of easy to use and low-cost decision support tools for the monitoring and exploitation of the water resources at different spatial and user levels. A top-to-bottom string of adapted water management tools has successfully been installed to tackle the problems: from watershed (top) to field level (bottom), not to mention the 1200 ha irrigation scheme. Land use maps have been derived from satellite and aerial images. Combined with data from a network of hydrologic gauging stations, regional water use maps were established. Hot spots in inefficient water use could be geographically identified and more detailed actions undertaken. Scheme Information Management Information System (SIMIS) was put in place for the management of the regions irrigated rice scheme. A more equitable distribution for the ever diminishing available water resources could be elaborated. A public-private partnership was installed to guarantee its sustainability. Day to day water use on irrigated plots was monitored by soil humidity and crop canopy measurements. A simple field-crop-water balance model AquaCrop was calibrated and validated, and is used by extension workers to draft optimal irrigation charts. Each tool is applied independently, requiring only limited data; but their combined results contribute to an improved integrated water management. [less ▲]

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See detailModes intentionnels
Dewalque, Arnaud ULg

Conference (2014, March 07)

Je dresse le bilan de la situation des recherches actuelles en théorie de la perception (entre représentationalisme et relationalisme), et je suggère que la voie d'investigations la plus prometteuse est l ... [more ▼]

Je dresse le bilan de la situation des recherches actuelles en théorie de la perception (entre représentationalisme et relationalisme), et je suggère que la voie d'investigations la plus prometteuse est l'intentionalisme modal. D'après l'intentionalisme modal, un état mental est individualisé par son contenu intentionnel et par son mode intentionnel. En m'appuyant sur la méthode descriptive de Franz Brentano, je propose alors un argument en faveur de cette conception: l'argument de la complétude. [less ▲]

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Peer Reviewed
See detailMicroplastics caught in herring gill rakers: illustration by scanning electron microscopy
Collard, France ULg; Das, Krishna ULg; Parmentier, Eric ULg

Conference (2014, March 07)

Plastics are produced in huge quantity (280 million of tons in 2012) and more than 10% end up in the oceans. It is estimated that between 60 and 80% of all marine debris are plastics. Plastics are ... [more ▼]

Plastics are produced in huge quantity (280 million of tons in 2012) and more than 10% end up in the oceans. It is estimated that between 60 and 80% of all marine debris are plastics. Plastics are persistent and have accumulated in the oceans for several decades. Plastics may adverse wildlife in many ways: they can be ingested by marine vertebrates and cause internal wounds in the digestive tract. Plastics are also vectors of organic pollutants including. Once ingested, plastics may release these pollutants in the organism. Plastics present in the marine environment fragment in small pieces by mechanical stress and UV radiation leading to the so-called microplastics smaller than 5 mm. Little is known about microplastics ingestion and toxicity in planktivorous fish such as the herring, Clupea harengus. Planktivorous fish have gill rakers, which may function as a trap for microplastics. This study aims to describe and characterise microplastics present on gill rakers of the herring, Clupea harengus. Ten gill cavities were sampled in January 2013 in the Channel and the North Sea during a fishery campaign organized by the IFREMER. Gills cavities were placed in a fixating solution until preparation for scanning electron microscopy (SEM). SEM was used in order to detect microplastics which are too small to be observed by a dissection microscope, to compare them with the distance between gill rakers and to characterise the surface and the shape of microplastics. Scanning electron microscopy revealed large variety of microplastics, which lengths ranged from 0.05 to 5mm. Relationship between microplastics length and distance between gill rakers was analysed on the same branchial arch. The present study revealed the presence of microplastics in an edible species of high economic value and raise question about potential impact on the herring and its consumers, including human beings. [less ▲]

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Peer Reviewed
See detailEquations fantaisistes : l'argent comme ressort burlesque dans l'œuvre de Pierre La Police
Belloi, Livio ULg

Conference (2014, March 06)

Conçue comme une vaste parodie du discours médiatique en général et de la presse quotidienne en particulier, la série "Véridique !" (Cornélius, 1999-2002) du dessinateur français Pierre La Police met ... [more ▼]

Conçue comme une vaste parodie du discours médiatique en général et de la presse quotidienne en particulier, la série "Véridique !" (Cornélius, 1999-2002) du dessinateur français Pierre La Police met volontiers en scène des questions ou des rapports d’argent. Le plus souvent lié à la sphère politique, le thème de l’argent autorise l’auteur à jeter un regard narquois et particulièrement acéré sur des événements qui firent grand bruit dans la France des années 1990 (l’affaire Roland Dumas, le scandale de l’ARC, l’affaire des emplois fictifs à la ville de Paris, etc.). Ma communication étudie au plus près les mises en scène de l’argent dans l’œuvre de Pierre La Police et s'efforce de porter au jour les véritables équations mises au point à cet égard par l’auteur. Toutes à leur manière, ces équations concourent à faire du thème de l’argent un ressort burlesque à part entière ; elles participent également d’une esthétique générale de la distorsion et de l’approximation, qui est comme la marque de fabrique de Pierre La Police. [less ▲]

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See detailEarly neuropsychological detection of Alzheimer's disease
Bastin, Christine ULg

Conference (2014, March 06)

Considering that brain pathology due to Alzheimer’s disease starts many years before the clinical symptoms become evident, subtle cognitive changes may exist already in the predementia phase. Different ... [more ▼]

Considering that brain pathology due to Alzheimer’s disease starts many years before the clinical symptoms become evident, subtle cognitive changes may exist already in the predementia phase. Different approaches have been used to detect initial cognitive impairments indicative of Alzheimer’s disease. One approach is the assessment of the predictive power of neuropsychological tools in characterizing patients with stable mild cognitive impairment (MCI) versus MCI patients who subsequently develop Alzheimer’s disease. Another approach is the longitudinal evaluation of large cohorts of older adults in population-based studies. Findings from several studies suggest that a memory test that ensures deep encoding of information and assesses retrieval with free as well as cued recall is a useful tool to distinguish patients at an early stage of Alzheimer disease from MCI non-converters. Impaired semantic memory has also been proposed as a neuropsychological marker of predementia Alzheimer’s disease. Beyond the memory domain, category verbal fluency has been shown to predict progression to Alzheimer’s disease. Moreover, combining neuropsychological scores of memory and executive functions and neuroimaging data allows a better discrimination between stable MCI and converters than neuroimaging data alone. Altogether, it is possible to detect cognitive changes that are predictive of the typical form of probable Alzheimer’s disease already in the predementia stage. Such at risk people are thought to be the best target for therapeutic interventions. [less ▲]

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Peer Reviewed
See detailIntentionalisme et représentationalisme de Brentano à Crane
Boccaccini, Federico ULg

Conference (2014, March 06)

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See detailL'utilisation de la spectrométrie (NIR) et l’imagerie hyperspectrale (NIR-HIS) proche infrarouge pour étudier la composition chimique et botanique de des fourrages
Dale, Laura-Monica ULg

Doctoral thesis (2014)

Forage quality or nutritive value is related to chemical composition, which can be determinated by laboratory methods. The NIR technique in comparison with classical methods is non-destructive, non ... [more ▼]

Forage quality or nutritive value is related to chemical composition, which can be determinated by laboratory methods. The NIR technique in comparison with classical methods is non-destructive, non-polluting, fast and relatively inexpensive per analysis. Investigations on nutritional quality of Carpathians Apuseni Mountains (Romania) grasslands are rarely performed with NIR technique. Therefore, the objective of the thesis was to develop non-destructive methods for evaluating the quality of feed originating from the Gârda area of the Carpathians Apuseni Mountains (Romania) potentially and to similar grassland arround the world. The first task was to study the potential of NIR spectroscopy for building a spectral database for forage quality based on a large collection of semi-natural grassland samples, using a ‘local’ calibration model built by the Walloon Agricultural Research Centre (CRA-W), in Belgium, to determine various parameters (e.g., protein, dry matter, ash, fibre, fat, aNDFom, ADF, lignin, digestibility, crude energy) from samples collected worldwide, outside Romania. The second task was to develop calibration models for an NIR-HSI system, which involved larger spectral data registration as an image. Until now, analyses to determine plant species were based on botanical composition evaluation, including visual observation, which is a subjective method involving identifying plants directly in the field. Distinguishing samples of pure grassland species can be time consuming, and it was therefore decided to build a spectral database of pure samples and then discriminate these samples into binary and ternary artificial sample mixtures. The main objective of these tasks was to identify the botanical families to which the samples belonged (Poaceae, Fabaceae and Other Botanical Families [OBF]). The focus was not on quantity monitoring, but rather on determining forage quality from stationary experiments in the grasslands. To conclude, this research has shown that it is possible to develop calibration models not only for quality assessment, but also for sample discrimination in dry powder samples. It was intended, that the mathematical models constructed and the database obtained, would be used for future research. [less ▲]

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