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See detailThe contribution of air-fluidization to the mobility of rapid flowslides
Stilmant, Frédéric; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

Conference (2016, April)

Air-fluidization can be the origin of the long runout of gravitational flows involving fine particles such as ash. An excessive air pore pressure dramatically reduces the friction angle of the material as ... [more ▼]

Air-fluidization can be the origin of the long runout of gravitational flows involving fine particles such as ash. An excessive air pore pressure dramatically reduces the friction angle of the material as long as this pressure has not been dissipated, which occurs during the flow. This phenomenon can be modelled thanks to the 2D depth-averaged equations of mass and momentum conservation and an additional transport equation for basal pore pressure evolu- tion (Iverson and Denlinger, 2001). ln this contribution, we discuss the application of this model in relation to recent experimental results on air- fluidized flows by Roche et al. (2008) and Roche (2012). The experimental results were used to set a priori the value of the diffusion coefficient in the model, taking into account the diference of scale between the experiments and real-world applications. We also compare the model predictions against detailed observations of a well-documented historical event, the collapse of a fly-ash heap in Belgium (Stilmant et al., 2015). In particular, we analyse the influence of the different components of the model on the results (pore pressure dissipation vs. pore pressure generation). The diffusion coefficient which characterizes the dissipation of air pore pressure is found sufficiently low for maintaining a fluidized flow over hundreds of meters. The study concludes that an air-tluidization theory is consistent with the field observations. These findings are particularly interesting as they seem not in line with the mainstream acceptation in landslide modelling that air generally plays a secondary role (e.g., Legros, 2002). [less ▲]

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See detailDistribution of uncertainties at the municipality level for flood risk modelling along the river Meuse: implications for policy-making
Pirotton, Michel ULg; Stilmant, Frédéric; Erpicum, Sébastien ULg et al

Conference (2016, April)

Flood risk modelling has been conducted for the whole course of the river Meuse in Belgium. Major cities, such as Liege (200,000 inh.) and Namur (l 10,000 inh.), are located in the floodplains of river ... [more ▼]

Flood risk modelling has been conducted for the whole course of the river Meuse in Belgium. Major cities, such as Liege (200,000 inh.) and Namur (l 10,000 inh.), are located in the floodplains of river Meuse. Particular attention has been paid to uncertainty analysis and its implications for decision-making. The modelling chain contains flood frequency analysis, detailed 2D hydraulic computations, damage modelling and risk calculation. The relative importance of each source of uncertainty to the overall results uncertainty has been estimated by considering several alternate options for each step of the analysis; different distributions were considered in the flood frequency analysis; the influence of modelling assumptions and boundary conditions (e.g., steady vs. unsteady) were taken into account for the hydraulic computation; two different landuse classifications and two sets ofdamage functions were used; the number of exceedance probabilities involved in the risk calculation (by integration of the risk-curves) was varied. In addition, the sensitivity of the results with respect to increases in flood discharges \vas assessed. The considered increases are consistent with a "wet" climate change scenario for the time horizons 202l~2050 and 2071-2100 (Detrembleur et al., 2015). The results of hazard computation differ significantly between the upper and lower parts of the course of river Meuse in Belgium. In the former, inundation extents grow gradually as the considered flood discharge is increased (i.e. the exceedance probability is reduced), while in the downstream part, protection structures (mainly concrete walls) prevent inundation for flood discharges corresponding to exccedance probabilities of 0.01 and above (in the present climate). For higher discharges, large inundation extents are obtained in the floodplains. The highest values of risk (mean annual damage) are obtained in the municipalities which undergo relatively frequent flooding (upper part of the river), as well as in those of the downstream part of the Meuse in which flow depths in the urbanized floodplains are particularly high when inundation occurs. This is the case of the city of Liege, as a result of a subsidence process following former mining activities. For a given climate scenario, the uncertainty ranges affecting flood risk estimates are significant; but not so much that the results for the different municipalities would overlap substantially. Therefore, these uncertainties do not hamper prioritization in terms of allocation of risk reduction measures at the municipality level. In the present climate, the uncertainties arising from flood frequency analysis have a negligible influence in the upper part of the river, while they have a considerable impact on risk modelling in the lower part, where a threshold effect was observed due to the flood protection structures (sudden transition from no inundation to massive flooding when a threshold discharge is exceeded). Varying the number of exceedance probabilities in the integration of the risk curve has different effects for different municipalities; but it does not change the ranking of the municipalities in terms of flood risk. For the other scenarios, damage estimation contributes most to the overall uncertainties. As shown by this study, the magnitude of the uncertainty and its main origin vary in space and in time. This emphasizes the paramount importance of conducting distributed uncertainty analyses. In the considered study area, prioritization of risk reduction means can be reliably performed despite the modelling uncertainties. [less ▲]

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See detailFirst steps of the regional climate model MAR over the Euro-CORDEX domain
Scholzen, Chloé ULg; Fettweis, Xavier ULg

Poster (2016, April)

In the framework of the Euro-CORDEX initiative, the Laboratory of Climatology of the University of Liège, Belgium, is currently using the regional climate model MAR (for “Modèle Atmosphérique Régional” ... [more ▼]

In the framework of the Euro-CORDEX initiative, the Laboratory of Climatology of the University of Liège, Belgium, is currently using the regional climate model MAR (for “Modèle Atmosphérique Régional”) to simulate the past, present and future climate over Europe. Simulations are to be performed for both available resolutions over the Euro-CORDEX domain, namely 0.11 deg. (12.5 km) and 0.44 deg. (50 km). Historical and present-day runs (1979-2015) will use the ERA-Interim and the NCEP/NCAR-v1 reanalyses as boundary conditions, whereas future projections will be driven by two selected GCMs from the CMIP5 database: NorESM1-M and MIROC5. All CMIP5-GCMs were previously compared against ERA-Interim reanalysis data in terms of their ability to represent the current mean climate over Europe. The GCMs also underwent a statistical classification based on the calculation of skill-scores evaluating for instance 850 hPa temperature and 500 hPa geopotential height. Several settings and parameters were tested in order to calibrate the regional climate model MAR over the Euro-CORDEX domain. MAR is to be validated against observations from the European Climate Assessment & Dataset (ECA&D). The final aim of this study is to assess the performance of MAR in comparing its results to other RCMs used within the Euro-CORDEX initiative. [less ▲]

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See detailLes institutions du travail
Counet, Maxime ULg

in Cornet, Jacques; Martin, Anne; Navarre, Sylvie (Eds.) et al Pratique des sciences sociales. Tome 2 (2016)

Detailed reference viewed: 11 (1 ULg)
See detailLes "piliers" et leurs associations
Counet, Maxime ULg

in Cornet, Jacques; Martin, Anne; Navarre, Sylvie (Eds.) et al Pratique des sciences sociales. Tome 2 (2016)

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See detailLes associations hors-piliers, les ONG et l'altermondialisme
Counet, Maxime ULg

in Martin, Anne; Navarre, Sylvie; Soutmans, Philippe (Eds.) et al Pratique des sciences sociales. Tome 2 (2016)

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See detailJugement Situationnel
Lothe, Benoit ULg; Hansez, Isabelle ULg

in Brangier, Eric; Dubois, Michel; Valléry, Gérard (Eds.) et al Psychologie du Travail et des Organisations : 110 notions clés (2016)

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See detailSelenium in Cattle: A Review
Mehdi, Youcef ULg; Dufrasne, Isabelle ULg

in Molecules (2016), 21(4), 545

This review article examines the role of selenium (Se) and the effects of Se supplementation especially in the bovine species. Selenium is an important trace element in cattle. Some of its roles include ... [more ▼]

This review article examines the role of selenium (Se) and the effects of Se supplementation especially in the bovine species. Selenium is an important trace element in cattle. Some of its roles include the participation in the antioxidant defense the cattle farms. The nutritional requirements of Se in cattle are estimated at 100 μg/kg DM (dry matter) for beef cattle and at 300 μg/kg DM for dairy cows. The rations high in fermentable carbohydrates, nitrates, sulfates, calcium or hydrogen cyanide negatively influence the organism’s use of the selenium contained in the diet. The Se supplementation may reduce the incidence of metritis and ovarian cysts during the postpartum period. The increase in fertility when adding Se is attributed to the reduction of the embryonic death during the first month of gestation. A use of organic Se in feed would provide a better transfer of Se in calves relative to mineral Se supplementation. The addition of Se yeasts in the foodstuffs of cows significantly increases the Se content and the percentage of polyunsaturated fatty acids (PUFA) in milk compared to the addition of sodium selenite. The enzyme 5-iodothyronine deiodinase is a seleno-dependent selenoprotein. It is one of the last proteins to be affected in the event of Se deficiency. This delay in response could explain the fact that several studies did not show the effect of Se supplementation on growth and weight gain of calves. Enrichment of Se in the diet did not significantly affect the slaughter weight and carcass yield of bulls. The impact and results of Se supplementation in cattle depend on physiological stage, Se status of animals, type and content of Se and types of Se administration. Further studies in Se supplementation should investigate the speciation of Se in food and yeasts, as well as understanding their metabolism and absorption. This constitute a path to exploit in order to explain certain different effects of Se. [less ▲]

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See detailLagrangian and arbitrary Lagrangian Eulerian simulations of complex roll-forming processes
Crutzen, Yanick ULg; Boman, Romain ULg; Papeleux, Luc ULg et al

in Comptes Rendus Mécanique (2016), 344(4-5), 251-266

The Arbitrary Lagrangian Eulerian (ALE) formalism is a breakthrough technique in the numerical simulation of the continuous-type roll-forming process. In contrast to the classical Lagrangian approach, the ... [more ▼]

The Arbitrary Lagrangian Eulerian (ALE) formalism is a breakthrough technique in the numerical simulation of the continuous-type roll-forming process. In contrast to the classical Lagrangian approach, the ALE formalism can compute the hopefully stationary state for the entire mill length with definitely effortless set-up tasks thanks to a nearly-stationary mesh. In this paper, advantages of ALE and Lagrangian formalisms are extensively discussed for simulating such continuous-type processes. Through a highly complex industrial application, the ease of use of ALE modelling is illustrated with the in-house code METAFOR. ALE and Lagrangian results are in good agreement with each other. [less ▲]

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See detailEffectiveness of High Intensity Radial Shock Wave Therapy in The Treatment of Chronic Plantar Fasciitis
Demoulin, Christophe ULg; Vanderthommen, Marc ULg; Fromm, Aurélien et al

in European Journal of Physical and Rehabilitation Medicine (2016, April), 52(Suppl. 1 No. 2), 733

Introduction: Literature is scarce concerning the effectiveness of high dose radial extracorporeal shock wave therapy (ESWT). Therefore, the aim of this study was to investigate its effectiveness on pain ... [more ▼]

Introduction: Literature is scarce concerning the effectiveness of high dose radial extracorporeal shock wave therapy (ESWT). Therefore, the aim of this study was to investigate its effectiveness on pain, function and pressure pain threshold in patients with chronicplantar fasciitis (PF). Materials and Methods: Patients with a diagnosis of chronic (pain lasting for more than 3 months) uni- or bilateral PF with a history of failed conservative treatment were included. After a 6-week control period during which no treatment occurred, a 2-week treatment period followed by a three weeks of rest (cicatrization phase) was provided. The treatment period consisted of three radial ESWT sessions (2000 impulses of 10 Hz frequency per session with an energy flux density of 0,275mJ/mm2) separated by a one-weekinterval. Patient assessments (pain intensity, foot function and pressure pain threshold (PPT) at the site of maximum local tenderness disability) were conducted at baseline, after the 6-week control phase (pre-treatment) and at the end of the cicatrization phase (post-treatment). Results: Thirty patients (19 women (63.3%)) with chronic PF and a mean age of 51.9±11 years were included in the present study. No drop-out occurred throughout the study period. No changes were observed at the pre-treatment assessment session except for pain intensity which decreased slightly but significantly (P<0.05). At the post-treatment session, highly significant (P<0.001) and clinically meaningful changes occurred for pain intensity (-34%), foot function score (-60%) and PPT (+68%). Conclusions: The present study suggests that high dose radial ESWT is a feasible and effective way to quickly and significantly decrease pain and disability in most patients with chronic PF. [less ▲]

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See detailImproved Thévenin equivalent methods for real-time voltage stability assessment
Perez, Angel; Johannsson, Hjortur; Ostergaard, Jacob et al

in proc. IEEE ENERGYCON Conference (2016, April)

An improved Thévenin equivalent method for real-time voltage stability assessment that uses wide-area information from synchrophasors is proposed. The improvements are a better modeling of the limited ... [more ▼]

An improved Thévenin equivalent method for real-time voltage stability assessment that uses wide-area information from synchrophasors is proposed. The improvements are a better modeling of the limited synchronous generators, and a processing that anticipates the effect of field current limiters, before the latter are activated. Several study cases using detailed dynamic simulations of the Nordic test system have been used to assess the performance of the proposed improvements. Their effectiveness is analyzed and, based on the results, their possible application in combination with the sensitivity-based voltage stability assessment method is explored. [less ▲]

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See detailTreeNET: Discovering and Connecting Subnets
Grailet, Jean-François ULg; Tarissan, Fabien; Donnet, Benoît ULg

in 8th International Workshop on Traffic Monitoring and Analysis (TMA) (2016, April)

Since the early 2000's, the Internet topology has been an attractive and important research topic, either for developing data collection mechanisms, and for analyzing and modeling the network. Beside ... [more ▼]

Since the early 2000's, the Internet topology has been an attractive and important research topic, either for developing data collection mechanisms, and for analyzing and modeling the network. Beside traditional aspects of the Internet topology (i.e., IP interface, router, and AS levels), recent researches focused on intermediate promising visions of the topology, namely Point-of-Presence (PoP) and subnets (i.e., a set of devices that are located on the same connection medium and that can communicate directly with each other at the link layer). This paper focuses on network subnet discovery by proposing a new tool called treenet. One of the key aspects of treenet is that it builds a tree representing the way subnets are located with respect to each other. This tree allows treenet to obtain additional information on the network, leading to better analysis of the collected data. In this paper, we demonstrate the potential of treenet through the evaluation of its key algorithmic steps and the study of measurements collected from the PlanetLab testbed. [less ▲]

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See detailUnveiling the MPLS Structure on Internet Topology
Davila Revelo; Anderson Ricci, Mauricio; Donnet, Benoît ULg et al

in 8th International Workshop on Traffic Monitoring and Analysis (TMA) (2016, April)

Recently, researches have been conducted to discover and assess the usage of MPLS tunnels. Indeed, recent developments in the ICMP protocol make certain categories of MPLS tunnels transparent to ... [more ▼]

Recently, researches have been conducted to discover and assess the usage of MPLS tunnels. Indeed, recent developments in the ICMP protocol make certain categories of MPLS tunnels transparent to traceroute probing. Additional techniques have been proposed to reveal the presence of MPLS tunnels when they do not explicitly appear in traceroute. It has been shown that MPLS is a very well deployed technology whose usage (i.e., Traffic Engineering, load balancing, etc.) varies in time and according to ASes. However, the MPLS structure on the Internet architecture has not been studied yet. In this paper, we follow this path by providing two contributions to the state of the art: (i) we evaluate the biases involved on MPLS tunnel detection when they are not directly revealed through traceroute. (ii), we provide some properties and architectural details related with MPLS deployment on router topology based on a k-core decomposition. [less ▲]

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See detailNon-invasive vagus nerve stimulation with the gammaCore® in healthy subjects: is there electrophysiological evidence for activation of vagal afferents ?
Schoenen, Jean ULg; NONIS, Romain ULg; D'Ostilio, Kevin ULg et al

Poster (2016, April)

Abstract: Background Non-invasive vagus nerve stimulation (nVNS) with the gammaCore® improves migraine and cluster headache. Animal experiments suggest that nVNS acts via stimulation of vagal afferents ... [more ▼]

Abstract: Background Non-invasive vagus nerve stimulation (nVNS) with the gammaCore® improves migraine and cluster headache. Animal experiments suggest that nVNS acts via stimulation of vagal afferents, but proof in humans is lacking. Vagal somatosensory evoked potentials (vSEP) are identified after invasive VNS or transcutaneous stimulation of auricular vagal branches, but late components could be muscle artifacts. Objective To search in healthy volunteers for reliable vSEP during nVNS with the gammaCore® Methods In 12 healthy subjects (7males) evoked potentials were recorded at A1/A2 (ref Cz) and C3/C4 (ref F3/F4) during 2-minute stimulation over left/right cervical vagus nerve with the gammaCore® (25Hz, 6-24V) and during stimulation over the inner tragus with a monopolar stimulator (2Hz, 50 stimuli, mean intensity 8mA). Results We identified 3 reproducible peaks P1, N1, P2 in 10 patients on the side of the gammaCore® stimulation at mean latencies of 2.05ms, 5.20ms and 9.13ms. P1-N1 amplitude increased significantly (p<0.01) with increasing voltage from 0.04μV to 0.52μV (C3/C4) and from 0.13µV to 2.04μV (A1/A2) respectively at 10V and 30V. Inner tragus stimulation elicited P1, N1, P2 peaks with shorter mean latencies (2.21ms, 3.72ms, 5.71ms) and a mean P1-N1 amplitude (A1/A2) of 5.0µV. When the gammaCore® was placed over the sternocleidomastoid muscle, there were no reproducible evoked potentials. Conclusion Non-invasive transcutaneous stimulation of the cervical vagus nerve with the gammaCore® elicits evoked potentials similar to those found with implanted electrodes or stimulation of Arnold’s nerve in the outer ear. The gammaCore®-evoked potentials increase in amplitude with stimulation intensity and disappear when the stimulator is positioned over neck muscles, suggesting that they are not muscle artifacts. Their short latency is compatible with their generation at the level of the foramen jugulare. The therapeutic effects reported with the gammaCore® in primary headaches can thus be mediated by genuine activation of vagus nerve afferents. [less ▲]

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See detailAnodal transcranial direct stimulation (tDCS) targeting the anterior cingulate gyrus for the preventive treatment of chronic cluster headache: a proof of concept trial.
MAGIS, Delphine ULg; D'Ostilio, Kevin ULg; Cosseddu, Anna et al

Poster (2016, April)

Background There is a need for better treatments in chronic cluster headache (CCH). In responders to percutaneous occipital nerve stimulation, the subgenual anterior cingulate gyrus (sACG) was found ... [more ▼]

Background There is a need for better treatments in chronic cluster headache (CCH). In responders to percutaneous occipital nerve stimulation, the subgenual anterior cingulate gyrus (sACG) was found hypermetabolic (Magis et al. 2011). We reasoned that activation of this area by transcranial neurostimulation could be effective in CCH. Aim To explore the preventive effect of anodal (i.e. activating) transcranial direct current stimulation (tDCS) targeting the anterior cingulate gyrus in CCH patients. Method & subjects Difficult-to-treat CCH patients with a stable preventive drug regimen applied tDCS (2mA) interictally in 20-minute daily sessions for 4 weeks with the anode positioned over the forehead (FpZ), the cathode over the C7 spinous process. Therapeutic effects were monitored with paper diaries. Results Nineteen patients were enrolled up to now. In 13 patients who completed the trial, mean weekly attack frequency decreased by 38% after 4 weeks of daily stimulation (W-test: p = 0.002). The 50% responder rate was 54%. Patients (n=12) reported an improvement in headache impact, as shown by 5-point decrease in the mean HIT-6 score (from 67 to 62, p = 0.02). In 10 patients who were followed up after the treatment period, the benefit remained stable up to 4 weeks after the last stimulation. The first 3 enrolled patients had superficial skin burns under the adhesive cathode electrode. Sponge electrodes were therefore used in all subsequent patients without any adverse effect. Conclusion Anodal tDCS targeting the anterior cingulate gyrus seems promising for the preventive treatment of chronic cluster headache as suggested by this ongoing proof-of-concept trial. Use of adhesive electrodes is not recommended. [less ▲]

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See detailMapping cortical modules, their connectivity and functions
Genon, Sarah ULg; Eickhoff, Simon

Conference (2016, April)

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See detailIs isokinetic exercise dangerous for the heart?
Le Goff, Caroline ULg; Kaux, Jean-François ULg; Cavalier, Etienne ULg et al

in European Journal of Physical and Rehabilitation Medicine (2016, April), 52(suppl. 1 No. 2), 457

INTRODUCTION: Very strenuous exercises can be performed on an isokinetic dynamometer in order to evaluate the resistance to fatigue of different muscular groups. Good cardiac function is necessary in ... [more ▼]

INTRODUCTION: Very strenuous exercises can be performed on an isokinetic dynamometer in order to evaluate the resistance to fatigue of different muscular groups. Good cardiac function is necessary in order to perform these very intensive exercises; otherwise an acute myocardial dysfunction could theoretically appear in predisposed patients. PURPOSE: Our study aimed to observe the cardiovascular impact (by biological point of view) of maximal intense isokinetic eccentric and concentric protocols performed by a population of sedentary young men. METHOD: Resting (T0) and post-exercise (just after (T1), 3 hours (T2) and 24 hours after the exercise (T3)) blood samples were taken in 2 populations of young sedentary men: 12 subjects (22.5±1.15 yo) for the eccentric protocol and 18 subjects (22.4±2.6 yo) for the concentric protocol. These subjects performed an intense maximal isokinetic exercise of the quadriceps muscles involving 30 knee flexions–extensions for each leg. We evaluated markers of cardiovascular risk (highly sensitive troponin T (hs-TnT), N-Terminal Brain natriuretic peptide (NT-proBNP), myoglobin (MYO)), of inflammation (highly sensitive C-reactive protein (hsCRP)), muscle damage (creatine kinase (CK)) and of oxidative stress (myeloperoxidase (MPO), lipidic peroxides (POXL), reduced (GSH) and oxidised glutathione (GSSG)). Haemodynamic parameters were measured continuously using a Portapres, and respiratory parameters were measured using a Sensormedics Vmax 29C. RESULTS: All the physiological parameters measured presented statistically significant changes. For the eccentric exercise, no significant modification in cardiac (NT-proBNP, hs-TNT) and inflammation (hsCRP) biomarkers was observed. However, a significant increase for CK (T3), MYO (T2), MPO (T1), POXL (T1), GSSG (T3) and ratio GSH/GSSG (T2-T3) was shown. For the concentric exercise, the results showed significant increases for the CK (T1-T2-T3), MYO (T1-T2), GSH/GSSG (T1). Evolutionary trends were also observed for the following biomarkers: NT-proBNP (T1-T2-T3), MPO (T2), and GSSG (T4). DISCUSSION and CONCLUSIONS: No modification in cardiac biomarkers was observed after the maximal eccentric isokinetic exercise but some variations can be observed for these biomarkers after the concentric exercise. However, these changes do not exceed the reference values in healthy subjects. We were thus able to prove that the exercise could be performed without any risk to cardiac function in young sedentary subjects. Nevertheless, a significant level of oxidative stress was induced by both exercises. [less ▲]

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See detailStudy of the genetic structure of the African buffalo populations (Syncerus caffer): Impact of its high mobility and of the population fragmentation on its distribution and its interactions with humans
Smitz, Nathalie ULg

Doctoral thesis (2016)

The African continent still hosts a unique diversified megafaunal community. However, phylogeographical patterns of African species have not yet been largely studied, as compared to the North American and ... [more ▼]

The African continent still hosts a unique diversified megafaunal community. However, phylogeographical patterns of African species have not yet been largely studied, as compared to the North American and European species. Moreover, nowadays, the African ecosystems suffer of considerable anthropogenic pressures and of severe climatic modifications. Wildlife population fragmentation resulting from habitat loss, drought, poaching and diseases is currently threatening many African species survivals. The present thesis aimed at investigating the phylogeography and the population genetic structure of the African buffalo (Syncerus caffer) at different spatio-temporal scales (phylogeographical scale vs demographic scale), based on different molecular markers (mtDNA D-Loop region, 17 microsatellites and a large set of ‘Single Nucleotide Polymorphisms’ (SNPs)). The African buffalo is an emblematic key species and provides a powerful model to enhance our understanding of the African biogeography and the species conservation requirements. The aim of the first part of the present work was to reconstruct the evolutionary history of the African buffalo based on the study of the mtDNA D-Loop hypervariable region. More particularly, we aimed at studying the impact of the Quaternary climatic fluctuations on the species distribution (i.e. phylogeographical scale). Moreover, one of our purposes was also to investigate the taxonomic controversies linked to the extreme within species morphological variability, using molecular tools. From a sample set including all four morphologically recognized subspecies roaming the sub-Saharan African continent (hereafter called ecophenotypes), two taxonomic units were supported by genetics. The genetic discontinuity was located between the West-Central (S. c. nanus, S. c. brachyceros and S. c. aequinoctialis) and the South-Eastern populations (S. c. caffer). The low amount of genetic differentiation within each of these two units, or lineages, was attributed to a recent (in evolutionary term) Pleistocene expansion in both lineages, with rapid adaptation to a variety of habitats. Using both microsatellites and a large set of SNPs, the second part of the present thesis aimed at investigating the impact of human activities and recent climatic changes on the population structure of the species (i.e. demographic scale). While mtDNA did not allowed to distinguish finer sub-structuration within the two identified lineages, suggesting high female gene flow at an evolutionary timescale, these last molecular markers allowed to identify eight different populations at the continental level: two in West-Central Africa, three in Eastern and three in Southern Africa. Both ancient (Neolithic revolution) and recent anthropogenic activities were proposed to have shaped the demographic population structure observed in Southern and Eastern Africa. Recently, two of these populations were shown to be under significant genetic drift, following severe demographic bottlenecks. In these two cases, the sharp reduction in the size of the populations was proposed to be linked to disease eradication campaigns and to overharvesting during civil wars. Nevertheless, they did not display a significant loss in heterozygosity, indicating that they are still genetically healthy. Interestingly, at the contact region between the S. c. caffer and the S. c. aequinoctialis savanna ecophenotypes, a population displaying a shared genetic pool was also identified, corroborating the existence of hybrids between the different forms (intermediate morphological characteristics). In conclusion, using various genetic approaches and molecular markers, the present work gained insights into the taxonomy and the evolutionary history of the African buffalo, as well as in its conservation management requirements. [less ▲]

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See detailHistopathological effects of Aspergillus clavatus (Ascomycota: Trichocomaceae) on larvae of the southern house mosquito, Culex quinquefasciatus (Diptera: Culicidae)
Bawin, Thomas ULg; Seye, Fawrou; Boukraa, Slimane ULg et al

in Fungal Biology (2016), 120(4), 489-499

Aspergillus clavatus (Ascomycota: Trichocomaceae) was previously found to be an opportunistic pathogen of mosquitoes (Diptera: Culicidae). In the present study, the mechanism leading to its insecticidal ... [more ▼]

Aspergillus clavatus (Ascomycota: Trichocomaceae) was previously found to be an opportunistic pathogen of mosquitoes (Diptera: Culicidae). In the present study, the mechanism leading to its insecticidal activity was investigated regarding histological damages on Culex quinquefasciatus larvae exposed to A. clavatus spores. Multiple concentration assays using spore suspensions (0.5 x 10^8 to 2.5 x 10^8 spores/ml) revealed 17.0% to 74.3% corrected mortalities after 48 h exposure. Heat-deactivated spores induced a lower mortality compared to non-heated spores suggesting that insecticidal effects are actively exerted. Spore-treated and untreated larvae were prepared for light microscopy as well as for scanning and transmission electron microscopy. Spores failed to adhere to the external body surface (except the mouth parts) of these aquatic immature stages but progressively filled the digestive tract where their metabolism seemed to activate. In parallel, the internal tissues of the larvae, i.e. the midgut wall, the skeletal muscles, and the cuticle-secreting epidermis, were progressively destroyed between 8 and 24 h of exposure. These observations suggest that toxins secreted by active germinating spores of A. clavatus in the digestive tract altered the larval tissues, leading to their necrosis and causing larval death. Fungal proliferation and sporulation then occurred during a saprophytic phase. A. clavatus enzymes or toxins responsible for these pathogenic effects need to be identified in further studies before any use of this fungus in mosquito control. [less ▲]

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