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See detailInter-system biases estimation in multi-GNSS relative positioning with GPS and Galileo
Deprez, Cécile ULg; Warnant, René ULg

Conference (2016, April 18)

The recent increase in the number of Global Navigation Satellite Systems (GNSS) opens new perspectives in the field of high precision positioning. Particularly, the European Galileo program has ... [more ▼]

The recent increase in the number of Global Navigation Satellite Systems (GNSS) opens new perspectives in the field of high precision positioning. Particularly, the European Galileo program has experienced major progress in 2015 with the launch of 6 satellites belonging to the new Full Operational Capability (FOC) generation. Associated with the ongoing GPS modernization, many more frequencies and satellites are now available. Therefore, multi-GNSS relative positioning based on GPS and Galileo overlapping frequencies should entail better accuracy and reliability in position estimations. However, the differences between satellite systems induce inter-system biases (ISBs) inside the multi-GNSS equations of observation. Once these biases estimated and removed from the model, a solution involving a unique pivot satellite for the two considered constellations can be obtained. Such an approach implies that the addition of even one single Galileo satellite to the GPS-only model will strengthen it. The combined use of L1 and L5 from GPS with E1 and E5a from Galileo in zero baseline double differences (ZB DD) based on a unique pivot satellite is employed to resolve ISBs. This model removes all the satelliteand receiver-dependant error sources by differentiating and the zero baseline configuration allows atmospheric and multipath effects elimination. An analysis of the long-term stability of ISBs is conducted on various pairs of receivers over large time spans. The possible influence of temperature variations inside the receivers over ISB values is also investigated. Our study is based on the 5 multi-GNSS receivers (2 Septentrio PolaRx4, 1 Septentrio PolaRxS and 2 Trimble NetR9) installed on the roof of our building in Liege. The estimated ISBs are then used as corrections in the multi-GNSS observation model and the resulting accuracy of multi-GNSS positioning is compared to GPS and Galileo standalone solutions. [less ▲]

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See detailReactive gases in the chemistry climate model ECHAM6-HAMMOZ
Schultz, Martin; Franco, Bruno ULg; Kaffashzadeh, Najmeh et al

Poster (2016, April 18)

The recently developed global chemistry climate model ECHAM6-HAMMOZ contains comprehensive and detailed schemes for tropospheric aerosol (HAM) and reactive gases chemistry (MOZ). The Jülich Atmospheric ... [more ▼]

The recently developed global chemistry climate model ECHAM6-HAMMOZ contains comprehensive and detailed schemes for tropospheric aerosol (HAM) and reactive gases chemistry (MOZ). The Jülich Atmospheric (chemical) Mechanism (JAM002) consists of more than 300 species and 650 reactions, including relatively detailed degradation pathways for various volatile organic compounds in the troposphere and stratosphere. State-of-the-art parameterisations for chemical and physical processes are included. Here we present evaluation results from a multi-year simulation of the present-day atmospheric composition. [less ▲]

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See detailTowards a better understanding of ephemeral stream morphodynamics during the last 100 ka in the vicinity of the prehistoric site of Ifri n’Ammar (Morocco)
Bartz, Melanie; Rhixon; Khel, Martin et al

Conference (2016, April 17)

Our study focusses on the ephemeral stream deposits of Wadi Selloum to reconstruct the palaeoenvironmental evolution in direct vicinity of the rock shelter Ifri n’Ammar. As one of the oldest settlement ... [more ▼]

Our study focusses on the ephemeral stream deposits of Wadi Selloum to reconstruct the palaeoenvironmental evolution in direct vicinity of the rock shelter Ifri n’Ammar. As one of the oldest settlement sites of anatomically modern humans (AMH) in North Africa, Ifri n’Ammar documents periodical occupations since ~170 ka. Since these discontinuous settlement dynamics may be related to or influenced by landscape changes and climate forcing, our study aims (i) to identify phases of morphodynamic activity and stability in the deposits of Wadi Selloum by using micromorphological (sixteen thin sections), sedimentological (laser diffractometry, loss on ignition, magnetic susceptibility), geochemical ( XRF and Scheibler method) and mineralogical (X-ray diffractometry) proxies. Furthermore, (ii) a robust chronology for the ephemeral stream deposits is established by applying a combination of optically stimulated luminescence (OSL) and post infrared stimulated luminescence (pIRIR290) dating. Additionally, one collected pottery shard was dated by thermoluminescence (TL) dating for an inter method comparison. The application of luminescence dating techniques to Wadi Selloum deposits yielded burial ages between 1.3 ± 0.2 ka and 102 ± 8 ka covering different phases of morphodynamically stable and active phases. Enhanced aggradation is evident between ~100 and 60 ka, ~21 and 14 ka and during the Holocene. Overbank fines are distinguished by high amounts of allochthonous minerals such as quartz, muscovite, K-feldspar and plagioclase which give rise to higher eolian activity. This leads to the suggestion that morphodynamical activity was dominant during more arid phases. Landscape stability was observed in form of one palaeosol (2B-2C-sequence; OIS 3) and a recent soil (Ap/Ah-Bw-Bk-BC-C-sequence; after LGM), both attributed to the Calcisol group. Pedogenenesis is evident in thin sections by well-developed subangular blocky peds. The main soil forming process is secondary carbonate precipitation in subsoil horizons, supported by pedofeatures such as calcite infillings and hypocoatings. Holocene deposits (6.4 ± 4 to 1.3 ± 0.2 ka) seem to be affected by short-termed changes between landscape stability and hydromorphic activity due to strong variations in its mineralogical and geochemical characteristics. This is supported by a homogeneous and sterile stratigraphy, as well as an insignificant differentiation in soil horizons with only weakly developed pedofeatures. The sediment characteristics present a weak Ap-C-sequence of a calcaric Fluvisol. After ~1.3 ± 0.2 ka fluvial discharge was reduced and incision took place in the Wadi Selloum. Our study provides first insights in the palaeoenvironment around Ifri n’Ammar during the last glacial interglacial cycle and gives first suggestions about climatic conditions during the time of human occupation in Ifri n’Ammar. [less ▲]

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See detailDrug-induced thyroid dysfunction
Geenen, Vincent ULg

Conference (2016, April 16)

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See detailGondwanan Palaeozoic plant spores: A review
Steemans, Philippe ULg; Gerrienne, Philippe ULg

Conference (2016, April 15)

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See detailFirst record of cryptospores in post-Hirnantian (latest Ordovician-early Silurian) sediments from Ethiopia
Brocke, R.; Bussert, R.; Lebenie, D. et al

Conference (2016, April 15)

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See detailLe billonnage cloisonné en agriculture des montagnes: évaluation et facteurs d'acceptation. Cas des Hauts Plateaux de l'Ouest-Cameroun
Djoukeng, Henri Grisseur ULg

Doctoral thesis (2016)

In the Western Highlands of Cameroon as in all other regions of the world where mountain agriculture is practiced, erosion and runoff pose a real threat to the sustainable preservation of natural ... [more ▼]

In the Western Highlands of Cameroon as in all other regions of the world where mountain agriculture is practiced, erosion and runoff pose a real threat to the sustainable preservation of natural resources. Generally, plots located on the slopes of the mountains in the Western Highlands have either become less productive or totally unproductive; this situation is exasperated by the scarcity of arable land which is largely attributed to cultural practices that do not take into account soil and water conservation methods. To better quantify the impacts of erosion and runoff on the different functions assigned to agriculture and agricultural holdings, this thesis has implemented tied ridging which is an unused soil and water conservation technique. We have thus compared the effectiveness of the existing soil preparation methods (ridging along the steepest slopes and flatbed cultivation) with tied ridging on two operating slopes namely 11% and 29%. The results showed a significant difference between the current practice (flatbed and ridging along the steepest slopes) and tied ridging in terms of soil loss (p = 0.003), yields (p = 0.003), and runoff water (p < 0.001). Under sole cropping of potato on a hectare of land, the tied ridging led to: (i) increase in populations of cultivated plants by 7%, (ii) significant reduction of runoff (lowered by a factor of seven) and soil loss (lowered by a factor of five), (iii) increase in yields by 80%, (iv) increase in farmer’s profitability by approximately 908388 FCFA.ha-1. The tied ridging needed 41% extra work regardless the slope of the land on which it was practiced. The tied ridging showed undeniable advantages: the stress of additional work was offset by the gain in yields for producer; additional work created additional job opportunities for the community; and tied ridging improved the conservation of soil and water for a healthy environment. Although the technique has several advantages, the provision of financial means for its implementation could be a negative point, because family labor supply is generally insufficient for its realization and the hired labor is expensive. Further work was dedicated to measuring the rate of adoption of the tied ridging technique and analysis of the determinants for adoption. The study showed that exploiting land ownership by farmers is a key factor in the implementation of soil conservation techniques. The results showed tied ridging adoption rates of 93% and 62% for dignitaries and other farmers respectively. Overall, access to land, operating slopes, and adoption of soil and water conservation techniques were significantly influenced by agronomic potentials of plots and socio-economic situation of farmers (p <0.05). Finally, in order to quantify the overall impact of tied ridging on the quality of surface water, we measured the proportion of sediments migrating from plots under the three soil preparation methods and entering to the river’s bed. The collected and measured sediments consisted of soil, plant residues, and other wastes (chemical packages, plastic casing used for irrigation, and food packages). The results showed that tied ridging cultivation method significantly reduced siltation of the Méloh River (p<0.05). Compared to 2012 and 2013, quantities of sediment decreased by 66% in 2014, the year in which the tied ridging technique was adopted on 75% of the plots. Thus the flatbed and ridging along the steepest slopes soil preparation methods are the principal cause of siltation and pollution of the Méloh River. The results of this research led to the following prospective approaches for improvement: (i) test the tied ridging technique with other crops and with different inter mounds’ spacing, (ii) study the facilitation of access to credit and creating farmer's organizations for promoting the adoption of tied ridging, (iii) test other soil and water conservation techniques such as live hedges, direct-sowing mulch-based crop (agroecology), and agroforestry, and (iv) conduct general limnologic studies of watersheds. The general limnology studies the surface waters according to their seasonal variations, and their physico-chemical and biological aspects. [less ▲]

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See detailFire Fragility Curves for Steel Buildings in a Community Context: A Methodology
Gernay, Thomas ULg; Elhami Khorasani, Negar; Garlock, Maria

in Engineering Structures (2016), 113

This paper proposes a novel methodology for developing fire fragility functions for an entire steel building - meaning that the function is not specific to a location within the building. The aim is to ... [more ▼]

This paper proposes a novel methodology for developing fire fragility functions for an entire steel building - meaning that the function is not specific to a location within the building. The aim is to characterize the probabilistic vulnerability of steel buildings to fire in the context of community resilience assessment. In developing the fragility functions, uncertainties in the fire model, the heat transfer model and the thermo-mechanical response are considered. In addition several fire scenarios at different locations in the building are studied. Monte Carlo Simulations and Latin Hypercube Sampling are used to generate the probability distributions of demand placed on the members and structural capacity relative to selected damage thresholds. By assessing demand and capacity in the temperature domain, the thermal and the structural problems can be treated separately to improve the efficiency of the probabilistic analysis. After the probability distributions are obtained for demand and capacity, the fragility functions can be obtained by convolution of the distributions. Finally, event tree analysis is used to combine the functions associated with fire scenarios in different building locations. The developed fire fragility functions yield the probability of exceedance of predefined damage states as a function of the fire load in the building. The methodology is illustrated on an example consisting in a prototype nine-story steel building based on the SAC project. [less ▲]

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See detailEpuisement des ressources et construction durable
Courard, Luc ULg

Scientific conference (2016, April 15)

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See detailNew 2016 MeSH addressing information gap, poverty, violence and danger of medicine set the tone for policy makers in patient care
Jamoulle, Marc ULg

in International Journal of Health Policy and Management (2016)

A careful review of the list of newly published Medical subject Heading in 2016 allows to identify 52 new or updated MESH in 2016 relevant to General Practice Family Medicine management (i.e. non-clinical ... [more ▼]

A careful review of the list of newly published Medical subject Heading in 2016 allows to identify 52 new or updated MESH in 2016 relevant to General Practice Family Medicine management (i.e. non-clinical) fields. Information society gap, poverty, violence and quaternary prevention related MeSH are outstandingly frequent. The 52 identified MeSH are proposed in supplementary material. [less ▲]

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See detailRytmes endocriniens circadiens
VALDES SOCIN, Hernan Gonzalo ULg

Scientific conference (2016, April 13)

A current research topic, that is developed in this presentation, is the study of disturbance of circadian hormonal cycles and the secretion of melatonin. Traumatic brain injury is associated to ... [more ▼]

A current research topic, that is developed in this presentation, is the study of disturbance of circadian hormonal cycles and the secretion of melatonin. Traumatic brain injury is associated to hypopituitarism in up to 10-35% of cases, depending on the dynamic tests used to diagnose hypopituitarism (Valdés-Socin & al 2009, Valdés-Socin & al 2015).Melatonin secretion and hormonal rhythms are severely disturbed in acute TBI patients (Seifman & al. Front Neurol 2014).Light is the primary variable that entrains the main circadian clock in the central nervous system. The retinohypothalamic tract generates an overt 24-hour rhythm. These coordinated outputs are conveyed through to the rest of the body via neuroendocrine (ie melatonin and ACTH-cortisol secretion), autonomic (sympathetic and parasympathetic pathways) and behavioral pathways (feeding, locomotor activity, etc).Finally, we will discuss some recent data connecting light pollution and nocturnal human activity with the metabolic syndrome (chronobesity). [less ▲]

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See detailLow-rank plus sparse decomposition for exoplanet detection in direct-imaging ADI sequences. The LLSG algorithm
Gómez González, Carlos ULg; Absil, Olivier ULg; Absil, P.-A. et al

in Astronomy and Astrophysics (2016), 589

Context. Data processing constitutes a critical component of high-contrast exoplanet imaging. Its role is almost as important as the choice of a coronagraph or a wavefront control system, and it is ... [more ▼]

Context. Data processing constitutes a critical component of high-contrast exoplanet imaging. Its role is almost as important as the choice of a coronagraph or a wavefront control system, and it is intertwined with the chosen observing strategy. Among the data processing techniques for angular differential imaging (ADI), the most recent is the family of principal component analysis (PCA) based algorithms. It is a widely used statistical tool developed during the first half of the past century. PCA serves, in this case, as a subspace projection technique for constructing a reference point spread function (PSF) that can be subtracted from the science data for boosting the detectability of potential companions present in the data. Unfortunately, when building this reference PSF from the science data itself, PCA comes with certain limitations such as the sensitivity of the lower dimensional orthogonal subspace to non-Gaussian noise. <BR /> Aims: Inspired by recent advances in machine learning algorithms such as robust PCA, we aim to propose a localized subspace projection technique that surpasses current PCA-based post-processing algorithms in terms of the detectability of companions at near real-time speed, a quality that will be useful for future direct imaging surveys. <BR /> Methods: We used randomized low-rank approximation methods recently proposed in the machine learning literature, coupled with entry-wise thresholding to decompose an ADI image sequence locally into low-rank, sparse, and Gaussian noise components (LLSG). This local three-term decomposition separates the starlight and the associated speckle noise from the planetary signal, which mostly remains in the sparse term. We tested the performance of our new algorithm on a long ADI sequence obtained on β Pictoris with VLT/NACO. <BR /> Results: Compared to a standard PCA approach, LLSG decomposition reaches a higher signal-to-noise ratio and has an overall better performance in the receiver operating characteristic space. This three-term decomposition brings a detectability boost compared to the full-frame standard PCA approach, especially in the small inner working angle region where complex speckle noise prevents PCA from discerning true companions from noise. [less ▲]

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See detailA Refined Method for Estimating the Global Hölder Exponent
Kleyntssens, Thomas ULg; Kreit, Damien; Nicolay, Samuel ULg

Conference (2016, April 12)

We give a wavelet characterization of the generalized Hölder spaces and show how this result can be applied to detect logarithmic corrections appearing in Brownian processes.

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See detailENMG appliquée à la pathologie (Second Master Médecine)
WANG, François-Charles ULg

Learning material (2016)

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See detailImpact of tillage practices on soil moisture dynamics in a temperate climate: potential of 3-D electrical resistivity tomography (ERT)
Chelin, Marie ULg; Hiel, Marie-Pierre ULg; Blanchy, Guillaume et al

Poster (2016, April 12)

Adapted agricultural soil management practices can enhance soil health by providing improved aggregate stability and soil structural quality. Hence water infiltration may be improved and plant water ... [more ▼]

Adapted agricultural soil management practices can enhance soil health by providing improved aggregate stability and soil structural quality. Hence water infiltration may be improved and plant water availability increased. In this study, we aim at quantifying the effect of tillage practices on the water dynamics in a loamy soil under temperate climate (Gembloux, Belgium). Therefore, we evaluated the ability of electrical resistivity tomography to estimate the water content at the field scale and under complex field conditions: varying pore water conductivity, rainfall, crop water uptake, root growth, varying temperature and changing soil structure due to tillage practices. During the summer of 2015, we studied four different treatments: conventional spring and winter tillage, strip tillage and a bare soil. We used ERT to estimate the spatio-temporal distribution of soil moisture. In each of the plots, 2 time-domain reflectometry (TDR) probes and 2 suction cups were installed. A calibration trench was constructed with 4 electrodes, 1 TDR probe and 1 temperature sensor at 4 different depths. We quantified changes of porosity over the growing season using X-ray tomography. Combining these data, we will investigate and quantify the effect of simultaneously changing pore water conductivity, soil porosity, soil temperature and soil moisture on the effectiveness of time-lapse ER measurements as a proxy for soil moisture changes under different tillage practices. [less ▲]

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See detailSTUDY AND CHARACTERIZATION OF MAGNETIC AND MULTIFERROIC MATERIALS BY FIRST-PRINCIPLES CALCULATIONS
Garcia Castro, Andrés Camilo ULg

Doctoral thesis (2016)

In the last fifteen years, multifunctional materials, and more specifically, multi- functional oxides have been widely studied due to its wide range of properties. Properties that go from ... [more ▼]

In the last fifteen years, multifunctional materials, and more specifically, multi- functional oxides have been widely studied due to its wide range of properties. Properties that go from superconductivity to ferroelectricity passing through mag- netism and multiferroism have been reported. Nonetheless, the fluoride family was left aside and little information is known about its possible ferroelectricity or mul- tiferroism. In this Ph.D thesis, we explored the electronic, vibrational, structural and magnetic properties of fluoride perovskite-based compounds. To such pur- poses, We performed ab-initio calculations based in the density-functional theory (DFT) as implemented in VASP and CRYSTAL codes. Our first step was to perform vibrational analyses in a large set of fluoroper- ovskites ABF3. Based on the results, we proposed a model that establishes an A-site geometrically driven ferroelectric vibrational instability in fluorides. Our studies reveal a different behavior as a function of isotropic pressure for NaBF3 with respect to oxides (e.g. BaTiO3) with B = Ca, V, Mn, and Zn. For these compounds we found an increase of the ferroelectric instability as a function of hydrostatic pressure. This probably due to the “transformation” of eigendisplace- ments responsible for the mode that creates the corresponding instability. In particular, an increase of ionic A-site radii present a strong influence in FE-polar instability. We also have shown, based on our first-principles calculations and symmetry theory analysis that all post-perovskites ABX3 with an active magnetic B-site cation can exhibit a noncollinear magnetic configuration, which happens to be allowed by symmetry. With these findings, the magnetic properties found exper- imentally were clarified for this particular high-pressure phase perovskite found at the Earth’s mantle. Additionally, We have predicted that NaMnF3 suffers a structural phase transition under pressure to a post-perovskite phase, where non- collinear ferromagnetism and large magnetic moment components are obtained within this high-pressure phase.. Going beyond, We have shown that it is possible to achieve multiferroic-induced state in NaMnF3 under epitaxial strain at compressive or tensile strain. We found a nonlinear behavior of the ferroelectric instability as well as a non-linear piezo- electric response as a function of epitaxial strain. The later completely different as the one found in oxide perovskites. Similarly, an out-of-plane polarization was observed, a property that has not been observed in oxides. We observed a Na + Mn sites cooperative ferroelectric ordering for compressive strain against a pure A-site geometrically driven ferroelectricity at tensile values of the ac-strain. Magnetic ordering reveals a non-collinear ground state with the GzAxFy repre- sentation. Even more interesting, and non-linear magnetoelectric coupling was found under the strained Pna1 ground state becoming the first known multifer- roic/magnetoelectric perovskite fluoride. Later, in order to go further, We studied the electronic and structural proper- ties of novel heterostructures based on oxyfluorides (KTaO3)n/(KBF3)l B = Zn and Ni interfaces. We found that the orbital levels splitting at the interfaces is strongly modified by the O–B–F coordination. The polar catastrophe phenomena also takes place in the oxyfluoride interfaces similarly to oxide heterostructure, however, we found that less number of layers are needed in order to achieve the insulator-to-metal transition when comparing to SrTiO3/LaAlO3 superlat- tices. We observed that the magnetism in the KTaO3/KNiF3 exhibits a moment magnitude modulations. Nevertheless, the magnetic structure keeps the G-type antiferromagnetism such as in the bulk former compound. Surprisingly, we ob- served a large k3-Rashba type splitting in at the oxyfluoride interfaces, at least four times larger than the one reported in SrTiO3/LaAlO3 interface and twice of the KTaO3-based transistor. In conclusion, we observed that fluorides-perovskites are good prototypes for multifunctional properties as oxides. Therefore, based on the results reported in this thesis, we expect that experimentalist and theoreticians can be motivated in characterization of fluorides, which can lead to a new set of unexplored materials with potential novel applications in electronics. [less ▲]

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See detailDocteur
Poskin, Antoine ULg

Doctoral thesis (2016)

During summer 2011, cattle presented severe hyperthermia combined with dropped milk yield and diarrhoea from unknown origin. In October 2011, blood was collected from cattle presenting these clinical ... [more ▼]

During summer 2011, cattle presented severe hyperthermia combined with dropped milk yield and diarrhoea from unknown origin. In October 2011, blood was collected from cattle presenting these clinical signs in Schmallenberg, a small city in West Germany. A new Orthobunyavirus, responsible for these unspecific clinical signs was identified and named Schmallenberg virus (SBV). Upon November 2011, an epizootic outbreak of abortion, stillbirths and malformed new-born was observed in bovine, ovine and caprine herds in Europe due to transplacental transmission of SBV to the foetus. The SBV vectors are small hematophagous midges of the gender Culicoides. This work contributed to estimate the impact of the SBV epidemic in Belgium (Study 1). On the basis of farmer’s observations, between 0.5% and 4% of calves were aborted, stillborn or malformed due to SBV in 2011-2012. Abortions and stillbirths were not clear consequences of the SBV outbreak in cattle. In sheep, between 11% and 19% of lambs were aborted, stillborn or malformed due to SBV in 2011-2012. Deformed animal was the most important finding of SBV outbreak at herd level and an essential condition for the farmer to send suspected samples to the National Reference Laboratory (NRL) for SBV analysis. The results gathered from the study indicate that SBV surveillance and monitoring should be implemented by SBV RNA detection with rRT-PCR in organs collected from stillborn and deformed calves and lambs born in big herds. The high impact of SBV highlighted in the Study 1 was putatively explained by unknown host supporting the SBV activity. In this respect, the role of pigs had never been evaluated. This was essential considering the suggested role of the domestic pigs in the life- cycle of the SBV-closely related Akabane virus (AKAV) (Huang et al., 2003). The absence of RNAemia after experimental infection of piglets with SBV realized in the Study 2 of the i thesis suggests the absence of obvious role of domestic pigs in SBV life-cycle. The absence of RNAemia is indeed a strong indication that further spread of SBV from the pigs to the Culicoides during a blood meal of the vector is not likely to occur, therefore making impossible an SBV transmission. The limited and temporary seroconversion observed after SBV inoculation in only half of the inoculated piglets and the absence of seroconversion reported in a limited number of field collected samples support this consideration. To prevent SBV progression, it was crucial to further study the pathogenesis of SBV. The Study 1 proved that the most important clinical impact of SBV was the consequence of the malformed new-born; hereto it was particularly crucial to improve the knowledge on the development of the SBV-related teratogenic effects. In this respect, experimental infection of pregnant sheep with SBV constituted an appropriate research approach. An experimental model was therefore essential to standardize. This thesis contributed to the standardization of in vivo experiments (in collaboration with another working group) by determining the minimum infectious dose of an SBV infectious inoculum. This reference infectious serum must contain approximately 20 TCID50 to induce a homogeneous effective infection in sheep. This dose is rather low and could be inoculated by a single Culicoides under natural conditions. Beyond this minimum infectious dose, no dose dependent effect was observed in productively inoculated ewes, either in the duration of the RNAemia, the quantity of SBV RNA detected by rRT–PCR in the blood, or in the number of SBV RNA copies present in the organs collected at necropsy. The experimental model developed (partly) in the Study 3 was used to inoculate pregnant ewes at day 45 and 60 of gestation, and increase the knowledge on SBV transplacental transmission. The inoculation induced the persistence of SBV RNA in placental organs until birth. Schmallenberg virus RNA was recovered from the organs collected at birth from the lambs of both groups. However, the chance to obtain SBV RNA positive placental ii organs was significantly higher when the infectious inoculum was inoculated at day 60 of gestation. Positive organs in lambs included CNS and muscle, but no malformation was observed in new-born lambs. This absence of malformations suggests that SBV inoculation must occur earlier than the day 45 of gestation to produce teratogenic effects in sheep. Also, the persistence of SBV RNA in the foetal envelope is indicative of a putative mean for SBV overwintering. The Study 4 highlighted a 6 month persistent seroconversion in the absence of SBV surinfection. In the meantime, SBV circulation drastically dropped on the field and the absence of SBV circulation could induce the sheep to become seronegative under natural conditions. In the Study 5, the experimental model developed in the Study 3 was used to demonstrate that one single SBV inoculation can induce a protective immunity in sheep that persists during a minimum period of 15 months. This experiment highlights that 2 successive periods of SBV circulation, spared of one year, is not likely to induce malformations on the field the second year. Based on the experience gathered with the closely related AKAV, recurrent outbreaks of congenital events can be expected for a long period. Vaccination of seronegative animals could be used to prevent the deleterious effects of SBV in case of SBV re-emergence. During this epidemic, different surveillance approaches including syndromic surveillance, sentinel herd surveillance, cross-sectional seroprevalence studies and pathogen surveillance in vectors have proven their utility and complementarity and should be considered to continue in the future in order to monitor the SBV dynamic. [less ▲]

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See detailGenotypic characterization of T. mentagrophytes complex strains circulating in Belgium with the Diversilab® system.
SACHELI, Rosalie ULg; Utri, Tania ULg; ADJETEY BAHUN, Akolé ULg et al

Poster (2016, April 09)

Background Infections due to the zoophilic dermatophyte Arthroderma benhamiae are being more frequently diagnosed in Belgium since a few years. The most common source of infection is guinea pigs. This ... [more ▼]

Background Infections due to the zoophilic dermatophyte Arthroderma benhamiae are being more frequently diagnosed in Belgium since a few years. The most common source of infection is guinea pigs. This species which is referred to the Trichophyton species of A.benhamiae can cause tinea capitis, tinea corporis, tinea manus and more frequently tinea faciei. These strains appear with a bright yellow thallus in culture and do not easily sporulate making them difficult to identify. Sequencing of these strains reveals “Arthroderma benhamiae”. At the contrary white strains of T. mentagrophytes complex are identified by sequencing as “T. mentagrophytes variety interdigitale” or T. interdigitale. The aim of the study is the evaluation of the genetic heterogeneity of these two subtypes of the T. mentagrophytes complex by using the DiversiLab® system. Material and methods 32 strains were collected by the National Reference Center for mycoses between 2012 and 2015. The fungal strains were identified by microscopy or ITS sequencing. All strains appearing white with a yellow pigment in culture and being identified as “A. benhamiae” by DNA sequencing were included as well reference strains. Some selected strains appearing white in culture and being identified as “T. mentagrophytes var. interdigitale” by DNA sequencing were also included. The genotypic analysis was performed by the DiversiLab® system (bioMérieux) by DNA fingerprinting generation. Results Both groups showed huge differences in DNA fingerprints. The similarity calculated by the DiversiLab® tool between the two groups was 70%. This reflects a high genotypic heterogeneity regarding the two types of strains analyzed. This is surprising given that both groups belong to the same species complex. The comparison of these two distinct DNA fingerprints with the mold database of bioMérieux generated identification as “T. mentagrophytes” for both groups. We noticed that the library contained two distinct patterns of DNA fingerprints (profile 1, strains MK55-60 and profile 2, strains MK138-143). Yellow strains were highly similar to profile 1 and white strains were highly similar to profile 2. Unfortunately, no additional information regarding the subspecies implicated could be obtained from the manufacturer. However, this study demonstrates that it may represent respectively “yellow strains types Trichophyton species of A. benhamiae” and “ white strains types T. interdigitale”. Conclusion This study highlights the genotypic differences between two types of strains belonging to the T. mentagrophytes species complex. Yellow strains which incidence is increasing in Belgium are clearly different from other strains previously characterized and the DiversiLab® method shows a high efficiency for discriminating between these two species difficult to separate by microscopy. [less ▲]

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See detailImpacts of unusually high sea ice cover on Antarctic coastal benthic food web structure
Michel, Loïc ULg; Dubois, Philippe; Eleaume, Marc et al

Conference (2016, April 08)

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice ... [more ▼]

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, the sea ice cover of East Antarctica unexpectedly tends to increase, possibly in relation with changes in atmospheric circulation. Changes in sea ice cover are likely to influence benthic food web structure through modifications of benthic-pelagic coupling, disruption of benthic production and/or modifications of benthic community structure (i.e. resource availability for benthic consumers). Here, we studied shallow (0-20 m) benthic food web structure on the coasts of Petrels Island (Adélie Land, East Antarctica) during an event of unusually high spatial and temporal (two successive austral summers without seasonal break-up) sea ice cover. Using stable isotope ratios of C, N and S and the SIAR mixing model, we examined importance of several organic matter sources (benthic macroalgae, benthic biofilm, sympagic algae, suspended particulate organic matter and penguin guano) for nutrition of over 20 taxa of benthic invertebrates (sponges, sea anemones, nemerteans, sessile and mobile polychaetes, gastropods, bivalves, sipunculids, pycnogonids, amphipods, sea stars, sea urchins and sea cucumbers) spanning most present functional guilds. Our results provide insights about how Antarctic benthic consumers, which have evolved in an extremely stable environment, might adapt their feeding habits in response to sudden man-driven changes in environmental conditions and trophic resource availability. [less ▲]

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