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See detailHighly sophisticated compound droplets on fiber arrays
Weyer, Floriane ULg; Lismont, Marjorie ULg; Dreesen, Laurent ULg et al

Poster (2014, November)

The poster shows a drop of oil containing four soapy water droplets of four different colors : red, orange, green and blue. This sophisticated object is created thanks to a fiber array. Fiber networks ... [more ▼]

The poster shows a drop of oil containing four soapy water droplets of four different colors : red, orange, green and blue. This sophisticated object is created thanks to a fiber array. Fiber networks allow processes such as droplet motion, fragmentation, trapping, releasing, mixing and encapsulation. Therefore, by using a vertical fiber decorated with successive nodes, compound droplets can be created. A soapy water droplet, with a specific color, is placed at each intersection. Then, a silicon oil droplet glides along the vertical fiber, encapsulates and collects the water droplets at each node leading to the formation of a compound droplet with four different components. [less ▲]

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See detailEarly detection of university students in potential difficulty : a case study
Hoffait, Anne-Sophie ULg; Schyns, Michael ULg

Conference (2014, November)

Rate of success in the first year at University in Belgium is very low regarding other foreign universities. The University of Liege, as other Universities, has already taken different initiatives. But by ... [more ▼]

Rate of success in the first year at University in Belgium is very low regarding other foreign universities. The University of Liege, as other Universities, has already taken different initiatives. But by early identifying students who have a high probability to face difficulties if nothing is done, the Universities might develop adapted methods to attack the problem with more emphasis where it is more needed and when it is still possible. Thus we want to develop a decision tool able to identify these students to help them. For that, we consider three standard datamining methods: logistic regression, artificial neural networks and decision trees and focus on early detection, i.e. before starting at the University. Then, we suggest to adapt these three methods as well as the classification framework in order to increase the probability of correct identification of the students. In our approach, we do not restrict the classification to two extreme classes, e.g. failure or success, but we create subcategories for different levels of confidence: high risk of failure, risk of failure, expected success or high probability of success. The algorithms are modified accordingly and to give more weight to the class that really matters. Note that this approach remains valid for any other classification problems for which the focus is on some extreme classes; e.g. fraud detection, credit default... Finally, simulations are conducted to measure the performances of the three methods, with and without the suggested adaptation. We check if the factors of success/failure we can identify are similar to those reported in the literature. We also make a ``what-if sensitivity analysis''. The goal is to measure in more depth the impact of some factors and the impact of some solutions, e.g., a complementary training or a reorientation. [less ▲]

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See detailLa bibliothèque ouverte : hommage à Christine Pagnoulle
Decoster, Sara ULg

in Culture, le Magazine Culturel de l'Université de Liège (2014), hors série

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See detailLes forces de la négation dans l’image
Dondero, Maria Giulia ULg

in Acquarelli, Luca (Ed.) Au prisme du figural. Le sens des images entre forme et force (2014)

Ce texte vise à décrire un type particulier de forces inhérentes à la configuration de l’image. Il s’agit de forces qui mettent en crise la figuration et le caractère affirmatif de l’image, en les ... [more ▼]

Ce texte vise à décrire un type particulier de forces inhérentes à la configuration de l’image. Il s’agit de forces qui mettent en crise la figuration et le caractère affirmatif de l’image, en les détournant et en les rendant « hésitants ». Nous souhaitons démontrer que l’image n’est pas contrainte d’affirmer ce qu’elle met en scène : elle a également la capacité de le nier. La négation par l’image représente à nos yeux un défi majeur pour les sémioticiens du visuel et les théoriciens de l’art, notamment dans le cadre de recherches sur le langage de l’image, le métalangage visuel et, plus généralement, sur les capacités de l’image à développer un discours autonome par rapport au discours verbal [less ▲]

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See detailCeramic Materials for Dental Prostheses
MAINJOT, Amélie ULg

in Biomaterials (2014)

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See detailCost-effectiveness model for sofosbuvir in chronic hepatitis C
De Groote, K; Michielsen, P; DELWAIDE, Jean ULg

in Value in Health (2014, November)

Pan-genotypic cost-effectiveness has been demonstrated for sofosbuvir in comparison for the current standard of care in HCV in Belgium. Overall, the wheghted pan-genotypic ICER is 15.575 Euros.

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See detailReconstruction tomographique - Première approche
Seret, Alain ULg; Defrise, Michel

Book published by Presses Universitaires de Liège - First edition (2014)

First introduction to the field of (emission and transmission) tomography reconstruction : general principles, sinogram concept, backprojection operation, Radon transform, 2D and 3D analytic ... [more ▼]

First introduction to the field of (emission and transmission) tomography reconstruction : general principles, sinogram concept, backprojection operation, Radon transform, 2D and 3D analytic reconstruction, filtered backprojection, Feldkamp algorithm, iterative methods, algebraic and statistical approaches (Gauss and Poisson noise), 3D to 2D reduction. Full demonstration of most algorithms presented in the book are provided. [less ▲]

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See detailInfinite self-shuffling words
Charlier, Emilie ULg; Kamae, Teturo; Puzynina, Svetlana et al

in Journal of Combinatorial Theory - Series A (2014), 128

In this paper we introduce and study a new property of infinite words: An infinite word x, with values in a finite set A, is said to be k-self-shuffling (k≥2) if there exists a shuffle of k copies of x ... [more ▼]

In this paper we introduce and study a new property of infinite words: An infinite word x, with values in a finite set A, is said to be k-self-shuffling (k≥2) if there exists a shuffle of k copies of x which produces x. We are particularly interested in the case k=2, in which case we say x is self-shuffling. This property of infinite words is shown to be independent of the complexity of the word as measured by the number of distinct factors of each length. Examples exist from bounded to full complexity. It is also an intrinsic property of the word and not of its language (set of factors). For instance, every aperiodic word contains a non-self-shuffling word in its shift orbit closure. While the property of being self-shuffling is a relatively strong condition, many important words arising in the area of symbolic dynamics are verified to be self-shuffling. They include for instance the Thue–Morse word fixed by the morphism 0↦01, 1↦10. As another example we show that all Sturmian words of intercept 0<ρ<1 are self-shuffling (while those of intercept ρ=0 are not). Our characterization of self-shuffling Sturmian words can be interpreted arithmetically in terms of a dynamical embedding and defines an arithmetic process we call the stepping stone model. One important feature of self-shuffling words stems from their morphic invariance: The morphic image of a self-shuffling word is self-shuffling. This provides a useful tool for showing that one word is not the morphic image of another. In addition to its morphic invariance, this new notion has other unexpected applications particularly in the area of substitutive dynamical systems. For example, as a consequence of our characterization of self-shuffling Sturmian words, we recover a number theoretic result, originally due to Yasutomi, on a classification of pure morphic Sturmian words in the orbit of the characteristic. [less ▲]

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See detailBash Tapa (Iraq). The Pottery from the First Excavation Campaign
Mas, Juliette ULg

Conference (2014, November)

Bash Tapa is a circa 8 ha settlement, located 35 km South of Erbil, in Iraqi Kurdistan. Its exploration was began in September 2013 by a french archaeological mission, led by L. Marti (CNRS, Paris). When ... [more ▼]

Bash Tapa is a circa 8 ha settlement, located 35 km South of Erbil, in Iraqi Kurdistan. Its exploration was began in September 2013 by a french archaeological mission, led by L. Marti (CNRS, Paris). When the sounding carried out on the top of the site allowed us to explore middle-assyrian levels, the stratigraphical step trench excavated on the southern slope of the tell revealed six phases of occupation dating to the 3rd millennium BC, from the Ninevite 5 to the Early Dynastic III periods. A first evaluation of the pottery material recovered in this operation revealed that there are different traditions represented at the site. In fact, while the material dated from the beginning of the Early Bronze Age is clearly related to the Northern tradition, the most recent 3rd millennium levels identified so far have provided us with pottery which could be connected to Central Mesopotamia, and more specifically to the Diyala region. This paper will give a first overview of the pottery from the first campaign of excavation at Bash Tapa, mainly focusing on 3rd millennium material, its links with the other regions of Near East and its significance for chronology. [less ▲]

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See detailStress and singing accuracy: What is the relationship?
Larrouy, Pauline ULg

Conference (2014, October 31)

Singing in public can be stressful and stress affects the control of the fundamental frequency, i.e. a critical element to control in order to sing in tune. It seems thus clear that singing in public will ... [more ▼]

Singing in public can be stressful and stress affects the control of the fundamental frequency, i.e. a critical element to control in order to sing in tune. It seems thus clear that singing in public will have an influence on vocal accuracy. In addition, the quality of a musical performance can be lessened or enhanced if the performer experiences stressful conditions. In order to clarify the effects of stress on singing accuracy and to explore solutions to favor the positive consequences of stress, we ran an experiment in collaboration with the Royal Conservatory of Liège. Thirty-one music students were asked to learn a simple melody. There were then recorded in a stressful condition (i.e., a music examination) and a non-stressful condition. Two groups were defined according to the challenge level of the music examination (first and second music levels). Measurements were made by self-reported state anxiety (CSAI-2R questionnaire) and by observing heart rate activity (electrocardiogram) during each performance. In addition, the vocal accuracy of the sung performances (in terms of respect of melodic contour, precision of intervals and respect of the tonality) was objectively analyzed. As expected, state anxiety and heart rate were significantly higher on the day of the music examination than in the non-stressful condition for all the music students. However, the effect of stress was positive for the first-year students but negative for the second-year students, for whom the music examination was particularly challenging. In addition, highly significant correlations were found between the intensity of cognitive symptoms and the vocal accuracy criteria. This study highlights the contrasting effects of stress on singing voice accuracy. The results encourage searchers to take into account the stress level of the performer when evaluating singing accuracy. In addition, it seems pertinent to work on the perception of somatic and cognitive symptoms in higher music institutions and to try to diminish the stress level of students, in order to favor the positive consequences of stress on the quality of musical performances. Thanks to this method, we are actually focusing on studies designed to better understand the effects of stress on speaking voice. [less ▲]

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See detailPlutella xylostella (L.) infestations at varying temperatures induce the emission of specific volatile blends by Arabidopsis thaliana (L.) Heynh
Hien, Truong Thi Dieu ULg; Delory, Benjamin ULg; Brostaux, Yves ULg et al

in Plant Signaling & Behavior (2014)

The effect of combined abiotic and biotic factors on plant volatile organic compound (VOC) emissions is poorly understood. This study evaluated the VOC emissions produced by Arabidopsis thaliana (L.) Col ... [more ▼]

The effect of combined abiotic and biotic factors on plant volatile organic compound (VOC) emissions is poorly understood. This study evaluated the VOC emissions produced by Arabidopsis thaliana (L.) Col-0 subjected to three temperature regimes (17, 22, and 27 °C) in the presence and absence of Plutella xylostella larvae over two time intervals (0–4 and 4–8 h), in comparison to control plants. The analyses of VOCs emitted by Arabidopsis plants were made by headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). It was found that certain volatile groups (e.g., alcohols, ketones, aldehydes, and terpenes) are induced by both single factors (temperature or larval infestation) and combined factors (temperature and larvae interactions), whereas other volatile groups (e.g., isothiocyanates [ITCs] and nitrile) were specific to the experimental conditions. ITCs (mainly 4-methylpentyl isothiocyanate) were emitted from plants subjected to larval infestation at 17 and 27 °C after the two time intervals. The proportions of sulfides (mainly dimethyl disulfide) and 4-(methylthio) butanenitrile were significantly higher on herbivore-infested plants at 22 °C compared to the other treatments. Overall, our findings indicate that changes in all experimental conditions caused significant changes to the VOC emissions of Arabidopsis plants. Therefore, the interaction between temperature and larval feeding may represent an important factor determining the variability of volatile emissions by plants subjected to multiple simultaneous factors. [less ▲]

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See detailcaractérisation physico-chimique et minéralogique de matériaux calcaro-dolomitiques en vue de la production de liants et produits dérivés
Matamba Jibikila, Raphaël ULg

Doctoral thesis (2014)

Due to their abundance and availability, limestone and dolomitic rocks are among the most valued resources in the world. As natural stones, they have many applications, both in trade and industrial ... [more ▼]

Due to their abundance and availability, limestone and dolomitic rocks are among the most valued resources in the world. As natural stones, they have many applications, both in trade and industrial sectors. Moreover, regardless of the scope of these materials, they must meet specific mineralogical and mechanical or physico-chemical properties, depending on the sector. Environmental requirements and sustainable management of mineral resources, have forced companies to reduce the value of naturally occurring materials, focusing oriented processing of waste materials or alternative approach. Moreover, technological developments have led to new applications requiring maximum purity of the material also led farmers to manage natural resources in a more rational manner. Mbuji-Mayi Region in the Democratic Republic of Congo, has huge limestone and dolomitic deposit; located in the " Mbuji-Mayi Supergroup". Nevertheless, the city suffers from a serious lack of sustainable infrastructure to consolidate its development and remains dependent on the supply of construction and building materials from other regions, located sometimes more than 1000 km from the Mbuji-Mayi site. The aim of this thesis is to investigate the potential use of Mbuji-Mayi supergroup materials to produce binder or derivated products in a sustainable management of mineral resources way. Thus, dolomitic samples were taken from Kanshi S13B and S70 Lubi drill cores, while limestone facies are from artisanal quarries in the region. They were then prepared and characterized. Techniques used are: X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), thermogravimetric analysis and the differential scanning calorimetry (TG-DSC), optical microscopy (OM) and scanning electron microscopy combined with chemical microanalysis (SEM / EDX). The results obtained after raw materials characterization showed that the Mbuji-Mayi Supergroup contains pure dolomite (respective mean CaO and MgO contents of 20.5 and 30%), impure dolomites and impure limestones. uniaxial compressive strength test, water absorption coefficient, and porosity were measured. Results were satisfactory in terms of the use of materials such as rubbles or building stones. Thermal and microscopic analyzes of pure dolomite, showed that these materials have high added value in the areas of refractory, glass manufacture or dolomitic lime production. Finally, a binder (CS1c) prepared from impure limestone, posted quite sufficient characteristics for applications with low mechanical stress. Metakaolin prepared from local raw material, was used to improve the characteristics of the binder CS1c. The analysis of the properties of the mixture CS1c-metakaolin, helped us to understand the role of some mineral phases, in contributing to the development of mechanical strength of such binders.   [less ▲]

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See detailLa représentation commerciale comme objet principal du contrat
Kéfer, Fabienne ULg

in Revue de Jurisprudence de Liège, Mons et Bruxelles (2014), (2014/35),

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See detailEngineering of poly(2-oxazoline)s for a potential use in biomedical applications
Legros, Camille ULg

Doctoral thesis (2014)

This PhD work is based on the design of poly(2-oxazoline) (POx) hydrogels and nanogels, by chemical or physical cross-linking, aimed to be used for biomedical applications. Nanogels were first prepared in ... [more ▼]

This PhD work is based on the design of poly(2-oxazoline) (POx) hydrogels and nanogels, by chemical or physical cross-linking, aimed to be used for biomedical applications. Nanogels were first prepared in dilute media and in inverse emulsion based on a statistical copolymer made of 2-ethyl-2-oxazoline and ethylene imine units. These stimuli-responsive nanogels were swelling in acidic media and were cleaved in reductive environment. They proved to be non-cytotoxic and act as protein repellent. Second, a reactive platform based on a statistical POx polymer bearing aldehyde functionalities was engineered, enabling the synthesis of graft and cross-linked POx. Last, a block copolymer made of 2-methyl- and 2-isopropyl-2- oxazoline units, proved to self-assemble into micelles when heated above its LCST, for a short period of time (< 1h30). When annealed for a longer time (> 1h30), crystallization-driven self-assembly led to the formation of different morphologies (fiber rods and cross-linked micelles). [less ▲]

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See detailInjections de PRP et tendinopathies
Kaux, Jean-François ULg

Conference (2014, October 30)

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