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See detailMeasuring the Effect of Stochastic Perturbation Component in Cellular Automata Urban Growth Model
El Saeid Mustafa, Ahmed Mohamed ULg; Saadi, Ismaïl ULg; Cools, Mario ULg et al

in Procedia Environmental Sciences (2014), 22(Winter), 156168

Urban environments are complex dynamic systems whose prediction of the future states cannot exclusively rely on deterministic rules. Although several studies on urban growth were carried out using ... [more ▼]

Urban environments are complex dynamic systems whose prediction of the future states cannot exclusively rely on deterministic rules. Although several studies on urban growth were carried out using different modelling approaches, the measurement of uncertainties was commonly neglected in these studies. This paper investigates the effect of uncertainty in urban growth models by introducing a stochastic perturbation method. A cellular automaton is used to simulate predicted urban growth. The effect of stochastic perturbation is addressed by comparing series of urban growth simulations based on different degree of stochastic perturbation randomness with the original urban growth simulation, obtained with the sole cellular automata neighbouring effects. These simulations are evaluated using cell-to-cell location agreement and a number of spatial metrics. The model framework has been applied to the Ourthe river basin in Belgium. The results show that the accuracy of the model is increased by introducing a stochastic perturbation component with a limited degree of randomness, in the cellular automata urban growth model. [less ▲]

Detailed reference viewed: 227 (115 ULg)
Peer Reviewed
See detailGenetic structure of fragmented southern populations of African Cape Buffalo (Syncerus caffer caffer) based on microsatellite analysis
Smitz, Nathalie ULg; Cornélis, Daniel; Chardonnet, Philippe et al

Poster (2014, December 12)

Detailed reference viewed: 12 (3 ULg)
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See detailParticulate soils adherence and surface cleanability: influence of biomacromolecules at interfaces and of substrate hydrophobicity
Toure, Yetioman ULg

Doctoral thesis (2014)

Cleaning of particulate soils is an important issue in food and pharmaceutical production. Understanding the adherence of these soils is a fundamental requirement for improving surfaces cleanability. The ... [more ▼]

Cleaning of particulate soils is an important issue in food and pharmaceutical production. Understanding the adherence of these soils is a fundamental requirement for improving surfaces cleanability. The combination of particles and macromolecules substances appears in many processes. Adsorbed compounds from these mixtures may influence interactions at interfaces and thus fouling and cleaning. This thesis deals with a deeper understanding of the physico-chemical mechanisms affecting soiling and cleanability of open substrates in the presence of biomacromolecules (dextran, bovine serum albumin – BSA, beta-lactoglobulin – β-LGB). Model substrates were chosen according to their hydrophobicity. The influence of macromolecules was examined by introducing them in the quartz suspension taken as a model of hard hydrophilic soil used for soiling, or by conditioning the substrate prior to soiling. The substrates were pretreated with ethanol (-Eth.), piranha or UV-Ozone (-UVO); soiled by spraying the quartz suspensions, then dried, before cleaning assessment. The removal of the soiling particles was evaluated after exposure to water in a radial flow chamber (RFC). Auxiliary characterizations were surface tension and contact angle measurements, surface analysis of the substrate by X-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy (SEM). The interpretation of XPS data allowed the complexity due to the ubiquitous presence of organic contaminants to be coped with, and the surface composition to be expressed in terms of both the amount of adlayer and the mass concentration of adlayer constituents. The contact of substrates with proteins led to their adsorption, which dominated the composition of the organic layer with respect to contaminants initially present, and was not markedly desorbed upon rinsing. Dextran was easily removed in presence of water, independently on the substrate nature. Surface hydrophobicity was shown to influence the morphology of the aggregates resulting from drying. The rounder aggregates formed on polystyrene when soiling was performed with suspension in pure water are more sensitive to wall shear stress than flatter ones formed on more hydrophilic substrate. This is the result of the competing processes of droplet rolling and coalescing, on the one hand, and droplet spreading, on the other hand. It affects the shape and compactness of the adhering aggregates, the efficiency of shear forces upon cleaning and finally, the adherence of soiling particles. The presence of proteins (either native or denatured) at the interface improved strongly the cleanability of more hydrophilic substrate (glass, StSteel-UVO). This is attributed to the lower surface tension. The dependence of cleanability on capillary forces, and in particular on the liquid surface tension, is predominant as compared with its dependence on the size and shape of the soiling aggregates, which influence the efficiency of shear forces exerted by the flowing water upon cleaning. The cleanability of less hydrophilic substrate (stainless steel only pre-cleaned with ethanol) did not change markedly in the presence of proteins; this may be due to a more complex interaction between surface tension and contact angle, on one hand, and a more complex interaction between proteins and contaminants, on the other hand. The presence of dextran did not affect the cleanability, as neither the liquid surface tension nor the contact angle was appreciably affected. [less ▲]

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See detailOpen Access, dream or reality for scholars: The ULg experience
Thirion, Paul ULg

Conference (2014, December 12)

Since the “serial price crisis”, no institution in the world has been able anymore to provide to scholars with the scientific literature they need. Although it was the first reason why the scientific ... [more ▼]

Since the “serial price crisis”, no institution in the world has been able anymore to provide to scholars with the scientific literature they need. Although it was the first reason why the scientific community developed Open Access initiatives, it’s absolutely not the only one. Nowadays, the awareness has become so large that many research players have put OA on the agenda (NIH, WHO, H2020, Wellcome Trust, FRS-FNRS…). The two main existing complementary ways will be described (Green and Gold) and Fools’ Gold will be denounced (unfair gold, hybrid journals, predatory journals). The University of Liege is one of the world leaders in OA with Green and Gold initiatives. What benefits can scholars expect from OA as authors and as readers on the basis of that experience? [less ▲]

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See detailSymptômes neurologiques du bord latéral du pied et de la cheville
WANG, François-Charles ULg

Conference (2014, December 12)

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See detailSeasonal sampling and stable isotopes use to delineate seagrass phytodetritus macrofauna trophic ecology: baseline variation or actual diet change?
Remy, François ULg; Mascart, Thibaud ULg; Dauby, Patrick ULg et al

Conference (2014, December 12)

In Mediterranean exported seagrass macrophytodetritus accumulations, a diverse (more than 130 species) and abundant (up to 4900 id.m-2) macrofauna assemblage is found alongside meiofauna, microalgae ... [more ▼]

In Mediterranean exported seagrass macrophytodetritus accumulations, a diverse (more than 130 species) and abundant (up to 4900 id.m-2) macrofauna assemblage is found alongside meiofauna, microalgae, fungi and bacteria. Macrophytodetritus are mainly composed of poorly digestible yet highly colonized material: the dead leaves of the very productive (300 to 2000 g dry wt m-2 yr-1) endemic seagrass Posidonia oceanica. A key role may be played by macrofauna, and more particularly by litter vagile macroinvertebrates (invertebrates > 500µm), in the degradation, enrichment and carbon transfer from P. oceanica to coastal food webs. Indeed, results of gut content observations of the most abundant species show that even if only a few of these species ingest a large proportion of P.oceanica dead leaves fragments, most of the others ingest a small but non-negligible part, suggesting a potential role of the whole community in the mechanical fragmentation of the dead leaves. Mediterranean exported macrophytodetritus accumulations are very dynamic habitats with very variable food availability, quality, and composition. Such an inconstant habitat may result in drastic modifications of the invertebrate community but also of its trophic structure and ecology. To test this hypothesis of influence of pulsed availability, quality and composition of food sources on the vagile macrofauna diet, we took seasonal samples in Calvi Bay (Corsica, 8°45’E; 42°35’N), at two sites between August 2011 and May 2012. Gut content observations and C/N/S stable isotope analysis of bulk tissues were conducted on both the macrofauna and their potential food sources. Significant seasonal and spatial differences of ingestion patterns of the most abundant species were emphasised as were differences of isotopic signatures. “SIAR” Bayesian mixing model and “SIBER” package were used to analyse isotopic data and determine if these differences were due to actual diet modifications or only to baselines isotopic composition variations. [less ▲]

Detailed reference viewed: 17 (2 ULg)
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See detailSound production in piranhas and relatives: preliminary results
Melotte, Geoffrey ULg; Michel, Christian ULg; Parmentier, Eric ULg

Poster (2014, December 12)

Acoustic communication plays an important role in the life of many teleost species where it is mainly involved in agonistic and/or courtship behaviour(s). Despite the large number of species in the family ... [more ▼]

Acoustic communication plays an important role in the life of many teleost species where it is mainly involved in agonistic and/or courtship behaviour(s). Despite the large number of species in the family Serrasalmidae (92 species), sound production has been described only in some of them, particularly in the genera Serrasalmus and Pygocentrus. The aim of this study is to investigate the sound producing abilities of different Serrasalmidae species and to understand the corresponding mechanisms. Two herbivorous species of Serrasalmidae, Piaractus brachypomus and Metynnis lippincottianus, produce sounds composed of a single pulse. The mechanism involved in these species is not yet understood. In contrast, the calls emitted by several species of Serrasalmus and Pygocentrus are harmonic sounds composed of several pulses without inter-pulse interval. Their mechanism results from the forced vibration of the swimbladder following the contraction of sonic muscles that are attached to tendons surrounding ventrally the bladder. Another species, Pygopristis denticulata, is able to produce two types of sounds. The first sound consists of several pulses with irregular pulse period and is likely produced by a sonic muscle inserting on the skull and on the rostral part of the swimbladder. The second sound is multi-pulsed and, contrary to all other sounds described here, possesses a high dominant frequency suggesting a mechanism that does not involve the swimbladder and that remains to be determined. According to these results, Serrasalmidae seems to contain many species able to produce sounds by means of different mechanisms. [less ▲]

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See detailMaintaining the coexistence of forest species of different shade tolerances with close-to-nature forestry
Ligot, Gauthier ULg; Philippe, Balandier

Conference (2014, December 12)

Continuous-cover forestry has the goal of relying on natural regeneration, and maintaining irregular stand structure and tree species mixture. However, maintaining mixture of species with different shade ... [more ▼]

Continuous-cover forestry has the goal of relying on natural regeneration, and maintaining irregular stand structure and tree species mixture. However, maintaining mixture of species with different shade tolerances appears arduous with such a silvicultural system. Successfully managing irregular and mixed forests, relying on natural processes, requires a strong knowledge of the ecology of natural regeneration. In theory, regeneration dynamics depends upon the amount of transmitted radiation: shade-tolerant species dominate the regeneration under closed canopies whereas less shade-tolerant species dominate the regeneration under partially open canopies. Nevertheless, it explains hardly the difficulties faced by forest managers to maintain the coexistence of species of different shade tolerances. The purpose of this research is to define light requirements of two species with contrasting shade tolerances (Fagus sylvatica L. and Quercus petraea (Matt.) Liebl.) and, next, determining how understory light can be controlled by forest managers. We find that, contrary to our expectations, the shade-tolerant species outgrow the less shade-tolerant species in all light conditions. We next examine the effects of canopy structure and composition on understory light availability with a model of light interception by heterogeneous canopies. Various silvicultural treatments are tested in order to provide favorable understory light conditions for natural regeneration. The results underline that creating favorable understory light conditions for natural regeneration can be achieved with various regeneration treatments. However, the adequate reduction of stand density depends upon the chosen silvicultural strategies. The outcomes of this study highlight that the control of understory light can be insufficient to maintain the coexistence of species of contrasting shade tolerance, and provide guidelines for the management of understory light in heterogeneous forests. [less ▲]

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See detailImpact of Climate Change on “Aphid - Natural Enemies” Relationship
Boullis, Antoine ULg; Oostrom, Marjolein; Francis, Frédéric ULg et al

Poster (2014, December 12)

While the effects of global atmospheric changes on vegetation and associated insect populations (bottom-up interactions) are increasingly studied, how these gases affect the interactions between insects ... [more ▼]

While the effects of global atmospheric changes on vegetation and associated insect populations (bottom-up interactions) are increasingly studied, how these gases affect the interactions between insects and their natural enemies (top-down interactions) is less clear. As the efficacy of natural enemies is governed largely by behavioral mechanisms, changes in their prey-seeking behavior or the behavior of insect prey defenses can change the dynamics of insect populations. The impact of increases in atmospheric carbon dioxide concentrations on aphid population dynamic is well documented. However, nothing about their chemical ecology is reported in the literature. Aphids are using many chemical signals to communicate with each other or with their environment. For example aphids produce an alarm pheromone to signal the presence of a natural enemy (such as a predator or a parasitoid) in the colony. Moreover, this pheromone is used by natural enemies as a kairomone to locate aphid prey, and is thus at the center of aphid – natural enemies interactions. In this study, the impact of elevated CO2 concentration on the emission of the alarm pheromone in the aphid A. pisum is studied. Using a zNoseTM (Gas chromatograph enabling the fast analyze of the chemical composition of a sample), the kinetic of the EBF emission in real-time is set up for a single individual predated by a coccinellid predator Harmonia axyridis Pallas. This experimentation is done both for aphids reared under ambient atmospheric conditions and for individuals reared under elevated CO2 concentrations. We present the differences in terms of emission dynamic and discuss the potential of these results in terms of biological control. [less ▲]

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See detailA morphospace for the marine angelfishes (Pomacanthidae): patterns of diversity
Frederich, Bruno ULg

Poster (2014, December 12)

The Pomacanthidae (marine angelfishes) is an iconic reef fish family of about 88 species. They have a circum-global distribution on tropical to warm-temperate reefs. Marine angelfishes occupy a diverse ... [more ▼]

The Pomacanthidae (marine angelfishes) is an iconic reef fish family of about 88 species. They have a circum-global distribution on tropical to warm-temperate reefs. Marine angelfishes occupy a diverse range of trophic niches, ranging from spongivory and algivory to zooplanktivory. Previous morpho-functional analysis of this family mainly focused on the head region and gut morphology in a limited number of species. However a morphological study including a large sample of angelfish representatives is currently lacking. Here, I explore the diversity of body morphology in this reef fish group. I collected x-ray images of 228 museum specimens from 71 species and I used landmark-based geometric morphometrics to quantify the overall body shape variation within this family. In a test for interspecific allometry, the linear regression of shape variables onto size (LogTL; TL = total length) was significant (P < 0.001). However, the percentage of explained variance in this model (23%) showed no strong relation between size and body shape. Main shape variation across species was explored using a principal component analysis on shape variables. The two main axes (PC1 and PC2) explained 74% of the total variance of the dataset. Pomacanthus spp., which mainly feed on fixed invertebrates (sponges and tunicates), have deep body with high and angular cephalic profile (lowest values along PC1). Conversely, the zooplanktivorous Genicanthus spp., those have a more pelagic lifestyle, show a slender body with shorter anal fin (highest values along PC1). The pigmy angelfishes from the genus Centropyge, which group different diets (omnivory or algivory), show a more robust and rectangular body shape (high scores along PC2). This work provides the row data for future studies dealing with the mode of phenotypic diversification of Pomacanthidae during evolution. [less ▲]

Detailed reference viewed: 27 (2 ULg)
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See detailUmbilical hernia under local anaesthesia: tips and tricks
DETRY, Olivier ULg

Conference (2014, December 12)

Despite many studies confirming the feasibility and the interest of local anaesthesia for umbilical repair, its use is not generalized amongst the abdominal surgeons. The advantages of local anaesthesia ... [more ▼]

Despite many studies confirming the feasibility and the interest of local anaesthesia for umbilical repair, its use is not generalized amongst the abdominal surgeons. The advantages of local anaesthesia are indeed clear, including reduced costs, reduced hospital stay and reduced post operative pain. The success of the procedure depends on the skills and the motivation of the surgeon, of the nursing teams, and of the patient him/herself. The Mayo repair is ideally performed under local anaesthesia, but should be proposed to patients suffering from limited umbilical hernia with small defects. Prosthetic repairs might also be proposed under local anaesthesia, but large defects with rectus diastasis might require a full Rives/Stoppa repair in which local anaesthesia could not be sufficient. In obese patients, laparoscopic repair might be beneficial despite higher cost and longer hospital stay. Practically local anaesthesia requires some patience and quiet in the operative room. Operators should be aware that the action of local anaesthesia is delayed after injection. Local anaesthetics should be buffered and at body temperature at time of injection. Local anaesthetics containing Adrenalin allow longer pain control, with limitation of bleeding and less toxicity. Large and brutal movements should be avoided. Ligature and section of parts of greater omentum are feasible under local anaesthesia without patient discomfort. Tension free repair should be favoured, and during Mayo repair, the only painful part of the repair is often the closure of the defect with the different stiches. The surgical and anaesthetic techniques for umbilical hernia repair should be tailored to the specific characteristics of the umbilical hernia and of the patient. There is no method of choice that might fit for every patient. [less ▲]

Detailed reference viewed: 18 (1 ULg)
See detailKracauer : Photographie et Wirklichkeit
Barbion, Sébastien ULg

Scientific conference (2014, December 12)

Detailed reference viewed: 9 (4 ULg)
See detailDécouverte d'un gène du gigantisme
Beckers, Albert ULg

Scientific conference (2014, December 12)

Detailed reference viewed: 14 (4 ULg)
See detailLectures italiennes à Bruxelles (1500-1630)
Adam, Renaud ULg

Scientific conference (2014, December 12)

Cette journée d’étude a pour but de favoriser les rencontres et échanges entre chercheurs de disciplines transversales autour de la problématique de la réception du livre italien dans les anciens Pays-Bas ... [more ▼]

Cette journée d’étude a pour but de favoriser les rencontres et échanges entre chercheurs de disciplines transversales autour de la problématique de la réception du livre italien dans les anciens Pays-Bas et en Principauté de Liège. Son objectif est d’étudier les mécanismes qui ont permis à l'édition en italien produite à la Renaissance d'être lue et divulguée dans ces territoires. Sous quelles formes ont circulé les livres italiens ? En langue originale ou en traductions (française et/ou néerlandaise) ? Quels itinéraires ont empruntés les livres « italiens » depuis le nord des Alpes ? Qui sont les acteurs de cette diffusion ? Dans quel(s) milieu(x) culturel(s) le livre italien a-t-il trouvé son public ? Existe-t-il un « italianisme bibliophilique » dans les anciens Pays-Bas et en Principauté de Liège ? Comment ont été conservés les livres italiens depuis le XVIe siècle jusqu’à nos jours ? L’ambition de cette manifestation est de contribuer à renouveler les connaissances sur la production, la diffusion et la conservation d’ouvrages « italiens » à la première modernité, ces vecteurs indispensables à l’essor de l’Humanisme et de la Renaissance dans l’Europe continentale. [less ▲]

Detailed reference viewed: 19 (2 ULg)
Peer Reviewed
See detailThe cerato-mandibular ligament: an innovation for sound production and feeding in damselfishes (Pomacentridae).
Olivier, Damien ULg; Frederich, Bruno ULg; Spanopoulos-Zarco, Milton et al

Conference (2014, December 12)

The success of a taxonomic group can be promoted by a key character that allows the group to interact with its environment in a different way and to potentially occupy new niches. The Pomacentridae ... [more ▼]

The success of a taxonomic group can be promoted by a key character that allows the group to interact with its environment in a different way and to potentially occupy new niches. The Pomacentridae possess a synapomorphic trait, the cerato-mandibular (c-md) ligament, which joins the hyoid bar to the inner part of the lower jaw. It has previously been shown that this ligament is a key trait in communication in damselfishes because it enables them to slam the oral jaws shut causing teeth collision and sound production. This specific behavior of mouth closing could, however, also be used for other tasks, such as feeding. Many territorial damselfishes are referred to as farmers, due to their ability to manage algal crops on which they feed. This study hypothesizes that the c-md ligament provides an advantage for grazing filamentous algae, and should thus be considered a key trait for farming behavior. The kinematic patterns associated with sound production and biting filamentous algae or attached animal prey are all based on the same mechanism and are associated with a slam of the oral jaws. We observed that transection of the c-md ligaments makes the fish unable to perform such actions. This study shows that the c-md ligament is a key trait both for sound production and for grazing activities in damselfishes. The buccal jaw slam enables the fish to perform accurate strikes on small filamentous algae. This kind of bite probably plays a major role in farming activity and allows grazing damselfishes to occupy distinct niches, possibly increasing their competitive evolutionary success. [less ▲]

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See detailWhen microplastic is not microplastic: ingestion of artificial cellulose fibers by macrofauna living in seagrass macrophytodetritus
Collard, France ULg; Remy, François ULg; Gilbert, Bernard ULg et al

Poster (2014, December 12)

Vagile macroinvertebrates associated with Posidonia oceanica exported litter were sampled in August 2011, November 2011 and March 2012 in the Calvi Bay (Corsica), near the STARESO oceanographic station ... [more ▼]

Vagile macroinvertebrates associated with Posidonia oceanica exported litter were sampled in August 2011, November 2011 and March 2012 in the Calvi Bay (Corsica), near the STARESO oceanographic station. Contents of digestive tracts were analyzed and fibers of various sizes and colors were found. Fibers were found in 27.6% of the digestive tracts in the nine dominant species. No correlation was found between number of fibers and taxonomic or trophic level. There were no seasonal or spatial preferences and thus we hypothesize that the organisms ingest these fibers randomly throughout the year. Analyses performed with a Raman spectroscope showed that these fibers were composed of cellulose associated with a coloring agent following the fiber color. Red fibers were dyed with the Direct Red 28, blue fibers were dyed with Direct Blue 22. Analyses by a scanning electron microscope (SEM) showed that cellulose fibers had the particular morphology of artificial cellulose fibers called: viscose. Our SEM analyses were compared to literature. This comparison assessed that fibers found in digestive tracts were made of viscose. In a first approach, viscose fibers looked like microplastic fibers because of their color and shape. However, it appeared that these fibers were made of artificial cellulose which is very different than plastic in terms of impacts and fate in the organisms. This study highlights the importance of physico-chemical analyses such as Raman spectroscopy and SEM to certainly identify the composition of particles ingested by organisms. From an ecological point of view, the red coloring agent is known to be carcinogenic in mammals and fish. Consequently, this pollution could provoke an environmental problem for the P. oceanica litter vagile macrofauna. [less ▲]

Detailed reference viewed: 50 (6 ULg)