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Peer Reviewed
See detailApplication of ion beam techniques for cultural heritage knowledge and conservation
Aucouturier, M.; Bouquillon, A.; Chabanne, Dehlia et al

in Brai, Maria (Ed.) Tecniche di analisi di materiali nei Beni Culturali : volume degli atti del Workshop su: "Tecniche di analisi non distruttive di materiali lapidei naturali e artificiali nei Beni Culturali, Palermo 22 febbraio 2007 (2007)

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See detailApplication of isotopic tracers as a tool for understanding hydrodynamic behavior of the highly exploited Diass aquifer system (Senegal)
Madioune, Diakher Hélène; Faye, Serigne; Orban, Philippe ULg et al

in Journal of Hydrology (2014), 511

The Diass horst aquifer system located 50 km east of Dakar (Senegal) is exploited in two main aquifers covered by a sandy superficial aquifer: the confined/unconfined Palaeocene karstic limestone and the ... [more ▼]

The Diass horst aquifer system located 50 km east of Dakar (Senegal) is exploited in two main aquifers covered by a sandy superficial aquifer: the confined/unconfined Palaeocene karstic limestone and the confined Maastrichtian sandstone aquifer underneath. This system has experienced intensive groundwater abstraction during the last 50 years to supply increasing water demand, agricultural and industrial needs. The high abstraction rate from 1989 to 2009 (about 109,000 m3/d) has caused a continuous groundwater level decline (up to 30 m), a modification of the groundwater flow and salinization in parts of the aquifers. The objective of the study is to improve our understanding of the system functioning with regards to high pumping, identify the geochemical reactions that take place in the system, infer origin and timing of recharge by using mainly stable (δ18O, δ2H, 13C) and radioactive (3H and 14C) isotopes. Water types defined in the Piper diagram vary in order of abundance from Ca–HCO3 (65%), Ca/Na–Cl (20%), Na–HCO3 (3%) and Na–Cl (12%). Values of δ18O and δ2H for the superficial aquifer range between −5.8 and −4.2‰ and between −42 and −31‰, respectively. For the Palaeocene aquifer they range from −5.8 to −5.0‰ and from −38 to −31‰, respectively; values in the Maastrichtian aquifer are between −5.9 and −4.3‰ for δ18O and −38 to −26‰ for δ2H. Plotted against the conventional δ18O vs δ2H diagram, data from the upper aquifer exhibit a dispersed distribution with respect to isotopic fractionation while those of the Palaeocene and Maastrichtian aquifers are aligned parallel and slightly below/or on the Global Meteoric Water Line (GMWL) evidencing ancient waters which had evaporated during infiltration. The low tritium (generally <0.7 TU) and 14C (0.7–57.2 pmc) contents indicate predominance of older water being recharged during the Pleistocene and Holocene periods. However, few boreholes which exhibit high tritium (1.2–4.3 TU) and 14C (65.7–70.8 pmc) values indicate some mixture with recent water likely through faulting and vertical drainage from the upper to deeper aquifers as well as lateral flow along flow paths to the piezometric depressions created by pumping. [less ▲]

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See detailApplication of Laser Induced Breakdown Spectroscopy (LIBS) to the determination of transition probabilities of laser lines in Au II spectrum
Ortiz, M.; Mayo, R.; Biémont, Emile ULg et al

Conference (2007)

Experimental branching fractions for laser lines arising from excited states of 5d97s configuration of Au II have been determined by application of Laser Induced Breakdown Spectroscopy (LIBS). The ... [more ▼]

Experimental branching fractions for laser lines arising from excited states of 5d97s configuration of Au II have been determined by application of Laser Induced Breakdown Spectroscopy (LIBS). The experimental relative transition probabilities were converted into an absolute scale using theoretical values for the radiative lifetimes of the corresponding states, calculated in this work. Transition probabilities and radiative lifetimes have been determined by a relativistic Hartree - Fock method taking configuration interaction and core-polarization effects into account. A comparison of the present results with the available theoretical values has been made and shows a reasonable agreement although discrepancies are observed between theory and experiment for some transitions. [less ▲]

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See detailApplication of lasso penalization to differential item functioning detection
Magis, David ULg

Scientific conference (2013, February 26)

Identification of differential item functioning (DIF) in dichotomously scored items is often performed item by item. This approach increases the risk of false discovery errors (Type I error rate) as all ... [more ▼]

Identification of differential item functioning (DIF) in dichotomously scored items is often performed item by item. This approach increases the risk of false discovery errors (Type I error rate) as all items other than the tested one are assumed to be free of DIF. Some ad-hoc procedures, such as item purification and alpha level adjustment for multiple comparisons, have been studied in this context. The purpose of this talk is to focus on a different approach based on penalized likelihood estimation of a look-alike IRT model. Specifically, a Rasch model is being introduced with item-group interaction terms (i.e. DIF effects). Rather than obtaining pointwise estimates of the interaction parameters, which may be impossible because of high collinearity effects, the DIF effects are estimated with a lasso penalty term. Several criteria for optimally selecting the lasso tuning parameter are discussed, including cross-validation, AIC, BIC, and variants of these criteria. Preliminary results of a simulation study are presented and discussed. [less ▲]

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See detailApplication of Lempel-Ziv complexity to alignment-free sequence comparison of protein families
Bacha, Sofiène; Baurain, Denis ULg

Poster (2005, April)

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See detailAn application of luminescence dating to building archaeology: The study of ceramic building materials in early medieval churches in south-eastern England and north-western France
Blain, Sophie ULg

in Arqueologia de la Arquitectura (2010), 7

The research reported in this thesis concerns the re-evaluation of an archaeological assumption surrounding the origin of Ceramic Building Materials (CBM) used from the 9th to the 11th century in ... [more ▼]

The research reported in this thesis concerns the re-evaluation of an archaeological assumption surrounding the origin of Ceramic Building Materials (CBM) used from the 9th to the 11th century in religious buildings of north-western France and south-eastern England. Are the bricks used in the masonry structures Roman spolia or a novo productions? Amongst the dating methods that can contribute to building archaeology, it is the technique of stimulated luminescence applied to CBM that is the focus of this study. Results from thermoluminescence (TL) and optically stimulated luminescence (OSL) dating performed on 52 CBM samples from 11 churches showed that the practice of reusing Roman brick was commonplace in small parish churches, but also that brick-making was not a totally unknown skill of the early medieval craftsmen as it has long been supposed. Most importantly, by identifying that the building material is contemporary to the church, a defined chronology emerges resulting in a new and extremely useful reference point in the history of early medieval architecture. [less ▲]

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See detailApplication of magnetic susceptibility on different carbonate platform type
Da Silva, Anne-Christine ULg; Boulvain, Frédéric ULg; Mabille, Cédric ULg

in Abstract book 17th ISC - Fukuoka, Japan - 2006 (2006)

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See detailapplication of magnetic susceptibility on different carbonate platform types.
Da Silva, Anne-Christine ULg

Scientific conference (2008, November 27)

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See detailApplication of magnetic susceptibility on different carbonate platforms
Da Silva, Anne-Christine ULg

Scientific conference (2010, December 13)

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See detailApplication of magnetic susceptibility on different carbonate systems
Da Silva, Anne-Christine ULg

Scientific conference (2010, February 02)

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See detailApplication of magnetic susceptibility on Palaeozoic sedimentary rocks
Spassov, Simo; Da Silva, Anne-Christine ULg; Whalen, Michael et al

in Abstract book of the IAGA 11th Scientific assembly (2009)

Detailed reference viewed: 27 (3 ULg)