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See detailLacustrine clay mineral assemblages as a proxy for land-use and climate changes over the last 4 kyr: The Amik Lake
El Ouahabi, Meriam ULiege; Hubert, Aurelia ULiege; Allan, Mohammed ULiege et al

Poster (2017, May 10)

Lake sediments are sensitive to landscape changes and most of these changes seem to be modulated by land-use (anthropogenic factors) coupled to palaeoenvironmental/palaeoclimatic changes. In its detrital ... [more ▼]

Lake sediments are sensitive to landscape changes and most of these changes seem to be modulated by land-use (anthropogenic factors) coupled to palaeoenvironmental/palaeoclimatic changes. In its detrital fraction, the lacustrine sediments record the history of soil erosion within its catchment via the inputs of clays and others detrital products. Within a Mediterranean context, the study investigates the upper sediments infilling the central part of the Amik basin in southern Turkey. This tectonic basin was occupied and exploited by modern human at least since 6000-7000 BC. We focus on the clay mineralogy (x-ray diffraction on oriented aggregates) and magnetic susceptibility measurements (Bartington) of the sedimentary record in the area over the last 4000 years, to assess environmental changes in relation with the different land uses and/or weathering during the successive Bronze, Iron, Roman, Islamic/Ottoman and Modern civilizations. The clay fraction of Amik Lake sediments comprises smectite, kaolinite, illite, chlorite and chlorite/smectite mixed layers that are the inherited clay phases. A relative change in abundance and crystallinity and chemistry of illite attests that environmental conditions evolved in the Amik Plain from the Bronze to Modern Age in relation with climates and/or land-use changes. The history of the Amik Lake reveals different soil erosion episode. The most intense erosion phase occurred during the Bronze/Iron Ages as indicated by the clay and magnetic susceptibility proxies. The Roman period was an exceptional period with soil erosion products arriving from the watershed, probably due the water channelization. A reduction of soil erosion occurred during the post Roman period until nowadays. Significant pedogenesis transformations are evidenced, especially during the Islamic/Ottoman periods suggesting intense chemical weathering conditions related to climate change. [less ▲]

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See detailGestion d’un cas de brûlure étendue suite à une chirurgie de convenance
Picavet, Pierre ULiege; Jacobs, Morgane ULiege; Noël, Stéphanie ULiege et al

in Monde Vétérinaire (Le) (2017), 169

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See detailClay minerals behaviour in thin sandy clay-rich lacustrine turbidites (Lake Hazar, Turkey)
El Ouahabi, Meriam ULiege; Hubert, Aurelia ULiege; Lamair, Laura ULiege et al

Poster (2017, April 23)

Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing ... [more ▼]

Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing relationships between the flow characteristics and their deposits. In particular, flume experiments emphasize that the presence of clay plays a key role in turbidity current dynamics. Clay fraction, in small amount, provides cohesive strength to sediment mixtures and can damp turbulence. However, the degree of flocculation is dependent on factors such as the amount and size of clay particles, the surface of clay particles, chemistry and pH conditions in which the clay particles are dispersed. The present study focuses on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in stacked thin beds. Depositional processes and sources have been previously studied and three types were deciphered, including laminar flows dominated by cohesion, transitional, and turbulence flow regimes (Hage et al., in revision). For the purpose of determine the clay behavior in the three flow regimes, clay mineralogical, geochemical measurements on the cores allow characterising the turbidites. SEM observations provide further information regarding the morphology of clay minerals and other clasts. The study is particularly relevant given the highly alkaline and saline water of the Hazar Lake. Clay minerals in Hazar Lake sediments include kaolinite (1:1-type), illite and chlorite (2:1-type). Hazar lake water is alkaline having pH around 9.3, in such alkaline environment, a cation-exchange reaction takes place. Furthermore, in saline water (16‰), salts can act as a shield and decrease the repulsive forces between clay particle surfaces. So, pH and salt content jointly impact the behaviour of clays differently. Since the Al-faces of clay structures have a negative charge in basic solutions. At high pH, all kaolinite surfaces become negative-charged, and then kaolinite particles are dispersed, and the suspension is stabilized supported by our SEM observations. In alkaline water, kaolinite reveals a lower degree of consolidation. While, alkaline water has no measurable effect on illite and chlorite surface properties due to the absence of modifications in charge. Illite and chlorite form with other clasts clusters or aggregate structures in suspension when the particle interactions are dominated by attractive energies were formed. The aggregate structure plays a major part in the flow behavior of clay suspensions. Flocs will immobilize the suspending medium, and give rise to increasing viscosity and yield strength of the suspension. [less ▲]

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See detailParasitisme d’Apis mellifera adansonii (Latreille 1804) et de Meliponula bocandei (Spinola 1853) par Aethina tumida (Murray 1867): premier recensement au Gabon et impact sur la domestication
Fabre Anguilet, Edgard ULiege; Alabi, Taofic ULiege; Haubruge, Eric ULiege et al

in Entomologie Faunistique = Faunistic Entomology (2017), 70

The small hive beetle, Aethina tumida (Murray 1867), has been reported in many countries in sub-Saharan Africa. This parasite is considered as a minor threat to strong Apis mellifera (Linnaeus 1758 ... [more ▼]

The small hive beetle, Aethina tumida (Murray 1867), has been reported in many countries in sub-Saharan Africa. This parasite is considered as a minor threat to strong Apis mellifera (Linnaeus 1758) colonies in Africa and as a major threat during the transfer of wild colonies of Meliponula bocandei (Spinola 1853) in hives. There is no data for Gabon and the state of wild colonies is still poorly known. Then, this study aims (1) to make a first prevalence assessment of A. tumida in wild colonies of A. mellifera and M. bocandei in Gabon; (2) to verify the effectiveness of quarantine implementation during the transfer of M. bocandei in hives against A. tumida. For that, 59 nests of A. mellifera and 25 nests of M. bocandei were inspected in two locations. Twelve nests of M. bocandei were transferred in hives with a quarantine for 4 days while 12 nests were transferred without quarantine. Aethina tumida was observed in more than 70 % of A. mellifera nests and in a single nest of M. bocandei. No damage was observed in nests of A. mellifera. More than 60 % of brood sections in quarantine or not were destroyed by A. tumida in hives. This study provided first evidence of the presence of A. tumida in Gabon and the need to develop a more effective method to domesticate M. bocandei in hives. [less ▲]

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See detailMéthodologie de localisation de systèmes fixes d’identification de plaques minéralogiques sur le réseau routier
Trotta, Marie; Donnay, Jean-Paul ULiege

in Emsellem, Karine; Josselin, Didier; Sierra, Diego Moreno (Eds.) et al Actes de la Conférence SAGEO 2016 (2016, December 01)

Despite increasing use of ANPR cameratechnology, especially in criminal investigations, literature and the experience of the police with whom we worked, seem to show that there is no systematic method to ... [more ▼]

Despite increasing use of ANPR cameratechnology, especially in criminal investigations, literature and the experience of the police with whom we worked, seem to show that there is no systematic method to locate as adequately as possible these expensive facilities. Given a set of four categories of robberiesover one year localized within the province of Liège (Belgium), we propose a methodology based on a multi-criteria analysis, making use of density offenses, road density and the distance between the sites of the cameras. Multi-criteria approach can adjust the factorweightings for different types of offenses. In addition, the methodology is iterative, insofar cameras sites are located in successive phases. One result validation criteria is provided in the form of a territorial coverage rate considering the number of selected camera sites and the travel time from each of these sites. [less ▲]

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