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See detailStochastic multi-scale modelling of MEMS
Lucas, Vincent ULg

Doctoral thesis (2016)

When studying Micro-Electro-Mechanical Systems (or MEMS) made of poly-crystalline materials, as the size of the device is only one or two orders of magnitude higher than the size of the grains, the ... [more ▼]

When studying Micro-Electro-Mechanical Systems (or MEMS) made of poly-crystalline materials, as the size of the device is only one or two orders of magnitude higher than the size of the grains, the structural properties exhibit a scatter at the macro-scale due to the existing randomness in the grain size, grain orientation, surface roughness... In order to predict the probabilistic behaviour at the structural scale, we investigated the recourse to a stochastic 3-scale approach in this thesis dissertation. Estimating the scatter in the response of the structure is studied at macro-scale based on stochastic finite elements along with Monte-Carlo simulations. To produce accurate results, the mesh size of the finite element approach should be small enough so that the heterogeneities can be captured. This can lead to overwhelming computation if the microstructure is directly considered, thus justifying the recourse to stochastic homogenisation to define a meso-scale random field. Based on a stochastic model of this random field, the variability of the response of the structure can be computed. In this work, the micro-scale uncertainties are modelled based on measurements provided by the IMT-Bucharest institute. These uncertainties are then propagated towards the macro-scale for 3 different problems. The first one serves the purpose of verification. The variability of the resonance frequency of a micro-beam is computed and compared to a reference numerical solution. The second problem extends the 3-scale approach to the thermo-elastic case. Thus the uncertainties of the quality factor of 3D beams are studied with a modelling of the anchor. Finally, the third problem aims at propagating surface roughness uncertainties on the resonance frequency of thin plates. [less ▲]

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See detailSystemic biomarkers of collagen and elastin turnover are associated with clinically relevant outcomes in COPD.
Stolz, Daiana; Leeming, Diana Julie; Edfort Kristensen, Jacob Hull et al

in CHEST (2016)

BACKGROUND: Extracellular matrix remodeling (ECM) of the lung tissue releases protein fragments into the blood, where they may be detected as serological surrogate markers of disease activity in chronic ... [more ▼]

BACKGROUND: Extracellular matrix remodeling (ECM) of the lung tissue releases protein fragments into the blood, where they may be detected as serological surrogate markers of disease activity in chronic obstructive pulmonary disease (COPD). We aimed to assess the association of ECM turnover with severity and outcome of COPD. METHODS: In a prospective, observational, multicenter study including 506 patients with COPD, GOLD grades II-IV, we analyzed serum samples at stable state, exacerbation and 4 weeks after exacerbation, for a panel of 5 novel neo-epitopes including fragments of collagen type-III (C3M) and type-VI (C6M), pro-forms of collagen type-III (Pro-C3) and type-VI (Pro-C6) and neutrophil elastase-generated fragments of elastin (EL-NE) by ELISA. These neo-epitopes were also measured at stable state in a derivation cohort including 100 COPD patients. RESULTS: Serum levels of C3M, C6M, Pro-C3, Pro-C6 and EL-NE were associated with lung function. Patients with the lowest levels of Pro-C3 and Pro-C6 had more severe airflow limitation, hyperinflation, air trapping, and emphysema. Degradation of collagen type-III and -VI was associated with dyspnea. All ECM biomarkers, except Pro-C6, were increased at exacerbation as compared to stable state but, except EL-NE, did not differ between stable state and exacerbation follow-up in the crude and adjusted analyses. In Cox regression adjusted analyses, Pro-C3 was associated with a shorter time to exacerbation (HR 0.72[0.59-0.89] p=0.002) and Pro-C6 with survival (HR 2.09[1.18-3.71], p=0.011). CONCLUSIONS: Serum biomarkers of ECM turnover are significantly associated with disease severity and clinically relevant outcomes in COPD. [less ▲]

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See detailPrévalence de l’hypovitaminose D chez la femme enceinte : quelle est la situation en région liégeoise ?
VRANKEN, Laura ULg

Master of advanced studies dissertation (2016)

Vitamin D deficiency is a worldwide health problem, also during pregnancy, especially in women with limited access to sunlight due to minimal outdoor activity or heavy use of sunscreen, cultural practices ... [more ▼]

Vitamin D deficiency is a worldwide health problem, also during pregnancy, especially in women with limited access to sunlight due to minimal outdoor activity or heavy use of sunscreen, cultural practices or traditional clothing, and among women with dark skin pigmentation and poor dietary habits. Inadequate maternal vitamin D status in pregnancy is associated with poor fetal growth, impaired bone development and rickets in infants after birth. Furthermore, higher rates of preeclampsia and gestational diabetes are associated with low maternal vitamin D status during pregnancy. Toxicity of vitamin D is rare. Most countries recommend vitamin D supplementation during pregnancy but guidelines are controversial and inadequate compared to real mother’s and child’s needs. Wath’s the best strategy to follow and supplement mother during pregnancy? [less ▲]

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See detailElectric current crowding effects in microstructured superconductors
Adami, Obaïd-Allah ULg

Doctoral thesis (2016)

Many applications of modern electronic devices are based on thin film geometries including sharp turns, holes and exhibiting inhomogeneities. The inevitable detour of current streamlines around such ... [more ▼]

Many applications of modern electronic devices are based on thin film geometries including sharp turns, holes and exhibiting inhomogeneities. The inevitable detour of current streamlines around such obstacles cause an inhomogeneous current density profile giving rise to current crowding. The goal of my research is to highlight the current crowding effects in micro and nanopatterned superconducting films. [less ▲]

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See detailFertility progression in Germany: an analysis using flexible nonparametric cure survival models
Bremhorst, Vincent; Kreyenfeld, Michaela; Lambert, Philippe ULg

in Demographic Research (2016)

OBJECTIVE This paper uses data from the German Socio-Economic Panel (GSOEP) to study the transition to second and third births. In particular, we seek to distinguish the factors that determine the timing ... [more ▼]

OBJECTIVE This paper uses data from the German Socio-Economic Panel (GSOEP) to study the transition to second and third births. In particular, we seek to distinguish the factors that determine the timing of fertility from the factors that influence ultimate parity progression. METHODS We employ cure survival models, a technique commonly used in epidemiological studies and in the statistical literature but only rarely applied to fertility research. RESULTS We find that education has a different impact on the timing and the ultimate probability of having a second and a third birth. Furthermore, we show that the shape of the fertility schedule for the total population differs from that of ‘susceptible women’ (i.e., those who have a second or a third child). CONCLUSION Standard event history models conflate timing and quantum effects. Our approach overcomes this shortcoming. It estimates separate parameters for the hazard rate of having a next child for the ‘susceptible population’ and the ultimate probability of having another child for the entire population at risk. [less ▲]

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See detailHow do we understand Smart City? An Evolutionary Perspective
Crutzen, Nathalie ULg; Kummitha, Rama

Conference (2016, August 25)

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See detailNormative data on teachers’ voice use in real-life situations
Schiller, Isabel ULg; Morsomme, Dominique ULg; Alcoulombre, Anaëlle et al

Conference (2016, August 25)

Background As part of their working routine, teachers use their voice for extended periods of time. To compensate for adverse acoustic conditions and background noise, they are also required to speak at ... [more ▼]

Background As part of their working routine, teachers use their voice for extended periods of time. To compensate for adverse acoustic conditions and background noise, they are also required to speak at high intensities. Since teaching is acknowledged to be vocally demanding, several studies have investigated teachers’ vocal load, that is, the stress inflicted on the larynx during vocalization, which is thought to be influenced by duration, intensity and frequency of phonation. A promising method for analyzing teachers’ phonatory behavior in real-life situations is the use of a portable voice dosimeter that objectively documents vocal parameters. Depending on several factors, those parameters may vary within the teaching profession (Masuda et al., 1993; Morrow and Connor, 2011; Remacle, Morsomme, and Finck, 2014). With the aim of quantifying their vocal parameters and identifying the most at-risk teaching conditions, we have established a large database of French-speaking teachers. Based on this database, this study analyzed vocal loading differences with regard to gender, teaching level, and environment (professional versus extra-professional). Methods Seventy-six French-speaking teachers (15 males and 61 females) were monitored during one workweek using the Ambulatory Phonation Monitor voice dosimeter (KayPENTAX). The subjects included 21 kindergarten, 20 primary and 35 secondary school teachers. All male subjects were in the latter group. The vocal parameters analyzed were phonation time, intensity and fundamental frequency (F0). Results The statistical analysis revealed that, irrespective of gender, phonation time, F0 and intensity level were significantly higher in the professional environment than the extra-professional environment (p<.01). Among female subjects, the F0 of kindergarten teachers was significantly higher than that of primary school teachers, which in turn was higher than that of secondary school teachers (p<.01). The phonation time and intensity were also higher in female kindergarten teachers than other female teachers, but this difference did not reach significance. As expected, regarding gender differences, we found that female secondary school teachers spoke with significantly higher F0 than their male colleagues (p<.001). In the extra-professional setting, they also spoke with a significantly higher intensity (p<.05), but no such effect was found in the professional environment. Conclusion Overall, our subjects showed an increase in vocal loading parameters when they were at work compared to their free time. This confirms the results of earlier studies and demonstrates that teaching is an occupation with remarkably high vocal demands. The analysis of mean frequency showed that lower school levels were associated with higher-pitched voice. It can be assumed that kindergarten teachers adapt to the higher F0 of their young pupils and that their effort to maintain the pupils’ attention results in greater frequency variations. References Masuda, T., Ikeda, Y., Manako, H., & Komiyama, S. (1993). Analysis of vocal abuse: Fluctuations in phonation time and intensity in 4 groups of speakers. Acta Oto-Laryngologica, 113(3), 547–552. Morrow, S. L., & Connor, N. P. (2011). Comparison of voice-use profiles between elementary classroom and music teachers. Journal of Voice, 25(3), 367–372. Remacle, A., Morsomme, D., & Finck, C. (2014). Comparison of vocal loading parameters in kindergarten and elementary school teachers. Journal of Speech, Language, and Hearing Research, 57(2), 406–415. [less ▲]

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See detailDetermining new threshold temperatures for cooling and heating degree day index of different climatic zones of Iran
Roshan, Gh.R.; Ghanghermeh, A.A.; Attia, Shady ULg

in Renewable Energy : An International Journal (2016), 101(2017), 156-167

Iran is a country with a variety of different climates. Determining the threshold temperatures suitable for providing thermal and climatic comfort is necessary and vital to its population well-being. This ... [more ▼]

Iran is a country with a variety of different climates. Determining the threshold temperatures suitable for providing thermal and climatic comfort is necessary and vital to its population well-being. This research presents new threshold temperatures in order to calculate the degree day index required for heating and cooling by taking advantage of the 12 stations that are representative of the diversity of Iran's climate. Using Olgyay diagram, different bioclimatic ranges of 12 weather stations and their frequencies were compiled, processes and analysed. Mean daily data of temperature and relative humidity were used for the period of 1950e2010. Based on the frequencies of temperature readings falling in Olgyay's diagram comfort zone, representive temperature thresholds were selected based on 40 to 60 percentiles or (P20), 25e75% percentile (P50) and the threshold of 10e90% percentile. The findings of this study shows that Mashhad with 29.6% and Anzali with 2.33% of frequencies, have experienced the maximum and minimum days of comfort. After analyzing various percentiles to determine the threshold temperatures, it was observed that there is a little difference among the stations for determining the minimum threshold for the comfort. Differences are more obvious in the maximum thresholds. In total, minimum base temperatures (HDD) belonged to Ardabil stations that were 20.50, 20.90 and 20 deg C for P20, P50 and P80 respectively. The maximum temperature for calculating CDD with values of (P20 ¼ 25 C; P50 ¼ 26.25 C; P80 ¼ 27.50 C) is dedicated to Zabol station. The findings present more reasonable thermal comfort thresholds that can be used by architects, engineers and policy makers to achieve, in turn, more energy efficient homes and high quality indoor and outdoor living environments. [less ▲]

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See detailDobble, analyse d'un jeu de cartes
Rigo, Michel ULg

Conference given outside the academic context (2016)

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See detailNos écosystèmes sont-ils des alliés pour lutter contre le changement climatique?
Heinesch, Bernard ULg

Conference given outside the academic context (2016)

Les écosystèmes terrestres jouent un rôle dans le changement climatique. Ils peuvent notamment échanger des gaz à effet de serre avec l’atmosphère. Ils peuvent par exemple émettre ou séquestrer du CO2, du ... [more ▼]

Les écosystèmes terrestres jouent un rôle dans le changement climatique. Ils peuvent notamment échanger des gaz à effet de serre avec l’atmosphère. Ils peuvent par exemple émettre ou séquestrer du CO2, du CH4 et du N2O en fonction du type d’écosystème, de la façon dont l’homme les exploite et des conditions climatiques. Dans cet exposé, des exemples concrets d’expériences menées sur des forêts, des cultures ou des prairies wallonnes seront utilisés pour illustrer les avancées scientifiques récentes dans le domaine et apporter des réponses à des questions du type: «Est-ce qu’une grande culture permet de stocker du carbone ? Et une prairie ? Que devient le bilan si la prairie est pâturée par du bétail ? Quelles pratiques d’exploitation pourraient améliorer le bilan ?» Des exemples de projets menés au sein des écoles secondaires et associant les élèves et des chercheurs seront aussi présentés. [less ▲]

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See detailSeasonal variation in human brain function
Vandewalle, Gilles ULg

Conference (2016, August 25)

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See detailEtude des rôles du produit d'expression du gène M138L du virus Myxoma dans la pathogénie de la myxomatose
Boutard, Bérengère ULg

Doctoral thesis (2016)

Myxoma virus belongs to the Poxviridae family and induces a severe and often lethal disease called myxomatosis in the European rabbit (Bertagnoli & Marchandeau, 2015). Numerous genes of the virus encode ... [more ▼]

Myxoma virus belongs to the Poxviridae family and induces a severe and often lethal disease called myxomatosis in the European rabbit (Bertagnoli & Marchandeau, 2015). Numerous genes of the virus encode for proteins with immunomodulatory functions (Spiesschaert et al., 2011; Zuniga, 2002). Among them, it has been demonstrated that the virus encodes for an α-2,3-sialyltransferase (Jackson et al., 1999; Markine-Goriaynoff et al., 2004b) that catalyzes the transfer of sialic acid to the N and O-glycans of glycoproteins and glycolipids (Varki & Schauer, 2009). Glycans, and especially sialic acids, are known to play significant roles in interactions and recognition between cells and between cells and viruses (Cohen & Varki, 2010; Raman et al., 2005; Vigerust & Shepherd, 2007). The aim of this thesis was to better understand the roles played by the viral α-2,3-sialyltransferase in the pathogenesis of myxomatosis. Using the Lausanne strain as parental strain, we have constructed strains deficient for the M138L gene encoding the α-2,3-sialyltransferase, and a revertant strain. Although no difference could be detected between the strains in vitro, the M138L knockout strains were highly attenuated in vivo. Especially, we observed more neutrophils at the beginning of infection and then an important mononuclear cells infiltrate in the dermis of the primary sites of infection for rabbits infected with the M138L knockout strains. We then wanted to determine which viral and / or cellular proteins were affected by the viral α-2,3-sialyltransferase, to check if their modification could explain the phenotype that we observed. We showed that the viral M-T7 protein was sialylated by the viral enzyme. M-T7 is a homologue of the interferon-γ receptor (Mossman et al., 1995) which is also able to bind and inhibit several chemokines, to block the chemokine gradient formation and to inhibit the inflammatory cells attraction towards the site of infection (Alcami, 2003; Lalani et al., 1997). However, we could not detect any effect of sialylation on the secretion or the activity of the M-T7 proteins purified from the four strains, either in vitro or in vivo. Altogether , these results show that the viral α-2,3-sialyltransferase is a virulence factor of the virus that could act directly or indirectly on several immunomodulatory viral proteins, and so on the immune cells attraction and adaptive immunity development. [less ▲]

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See detailEtude des sémiochimiques volatils impliqués dans le mutualisme fourmis-pucerons
Fischer, Christophe ULg

Doctoral thesis (2016)

For decades, the mutualistic relationship that ant and aphids may present has fascinated entomologists, as evidenced by the abundant literature on the subject. The principles of this interaction are ... [more ▼]

For decades, the mutualistic relationship that ant and aphids may present has fascinated entomologists, as evidenced by the abundant literature on the subject. The principles of this interaction are simple: as long as their colony remains, aphids provide ants with a stable and abundant source of sugars, honeydew. In exchange, ants tend aphid colonies and provide them cleaning and protection against various natural enemies. Nevertheless, some aspects of this relationship remain misunderstood. This is for example the case of the factors influencing the search and the discovery of a potential partner, first step to any potential mutualistic interaction. The role held by volatile chemical cues, called semiochemicals, in this relationship is also misunderstood. The objective of this thesis is to improve understanding of the role played by volatile semiochemicals in this mutualistic relationship, especially during the partner search stage, both from the perspective of the ant and of the aphid. The black garden ant, Lasius niger L., and the black bean aphid, Aphis fabae Scop., constitute our biological model. The impact of volatile compounds on the search behavior of the ant has first been investigated. These compounds are from multiple origins, either directly emitted by the aphid or induced by its presence. First, the ability of ants to perceive E-β-farnesene, the main component of many aphid alarm pheromone, and to use it to locate aphid colonies has been highlighted. This compound has indeed shown attractiveness to ants, even at low doses corresponding to the emissions of an unstressed aphid colony. Then, the roles played by honeydew volatile compounds in ant attraction have been demonstrated. These compounds also allow ants to remotely discriminate different aphid species and to direct their searches accordingly. These semiochemicals are produced by honeydew microflora, and a particularly attractive bacterial strain, Staphylococcus xylosus, has been isolated from A. fabae honeydew. Finally, the active role of winged aphids, which are aphid’s dispersal form, in the search for a mutualistic partner was also studied. Aphids do not appear to be preferentially attracted toward a host plant frequented by ants or close an ant nest. Nevertheless, once a potential host plant reached, they remain longer on it in case of ant presence. This thesis highlights the importance of volatile semiochemicals and honeydew microflora in ant-aphid mutualistic relationships, thus completing by a new aspect an already well documented biological model. [less ▲]

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See detailAgeism in Belgium and Burundi: A comparative analysis
Marquet, Manon ULg; Missotten, Pierre ULg; Schroyen, Sarah ULg et al

in Clinical Interventions in Aging (2016), 11

Background: Recent cross-cultural comparisons between Asian and Western cultures have shown that ageism arises more from the lack of availability of social and economic resources for older adults than ... [more ▼]

Background: Recent cross-cultural comparisons between Asian and Western cultures have shown that ageism arises more from the lack of availability of social and economic resources for older adults than from the culture itself. We tested this assumption by conducting a survey among people living in a least-developed country compared with a developed country. Methods: Twenty-seven Belgians living in Belgium, 29 Burundians living in Belgium and 32 Burundians living in Burundi were included in this study. Their attitudes toward older adults were assessed using several self-reported measures. Results: Statistical analyses confirmed that older people are more negatively perceived by Burundians living in Burundi than by Burundians and Belgians living in Belgium, whose attitudes did not differ from each other. Conclusion: Consistent with our hypothesis, our results suggest that the level of development of a country and more particularly the lack of government spending on older people (pension and healthcare systems) may contribute to their younger counterparts perceiving them more negatively. [less ▲]

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See detailMESURES INCITATIVES A LA PRODUCTION COTONNIERE ET PERSPECTIVES DE LA PRIVATISATION DES FILIALES CMDT AU MALI
Koné, Bouréma ULg

Doctoral thesis (2016)

Cotton is the first export crop in Mali with 84,370 billion Fcfa in 2010 (INSTAT, 2010), but the production of this crop has huge problems due to external factors (prices of inputs and seed cotton) and ... [more ▼]

Cotton is the first export crop in Mali with 84,370 billion Fcfa in 2010 (INSTAT, 2010), but the production of this crop has huge problems due to external factors (prices of inputs and seed cotton) and internal (within payment to producers, internal debts of cooperatives). To boost cotton production during the years 2010/11 and 2011/12, the government had maintained the level of fertilizer subsidy at 50% of normal price on the market. In addition to this level of subsidy, the incentive price of 255Fcfa / kg was fixed to the producer and the National Union of Cotton Producers Cooperative Societies (NU-CPCS) facilitated the clearance of the internal debts of cooperatives. Despite the fall in world prices after 2011/12, the price of cotton seed remains little changed. The price stayed at 255 CFA francs / kg in 2012/13 and got back to 250 CFA francs / kg in 2013/14. The objective of this work is to analyze the effects of incentives factors cotton production with a view to the privatization of CMDT subsidiaries Surveys were conducted with a sample of 240 farms selected from the four zones of the CMDT zones based on two villages subsidiary during the years of 2008/09, 2010/11 and 2011/12. The results showed a positive trend in production (mainly due to an increase in the area) and in the income of cotton producers with a higher reimbursement rate of input credits under cultivation. The analysis of the Domestic Resource Cost (DRC) the Nominal protection coefficients (NPC) and the Effective (CPE) showed an improvement in thèse variables in 2011/12 with the incentive policy. An analysis of the determinants of the supply of cotton showed that only two variables were significant: the price cottonseed and payment period. The incentive factors are influenced by fiber market in 2011/12 which took a downward trend from the campaign. This incentive policy being favored by the market of fiber which is very unstable, it would be necessary to create conditions in which the producer can benefit from the price obtained on the quality of fiber to maintain the incentive policy for producers. For the privatization of Cotton Company, an upgrade of this company is necessary with the support of the Malian state. But this upgrade should not affect too much the selling price of sale of cotton that can bring new companies in a situation of too long term recovery of capital invested (long period of investment recovery). The privatization scheme as presented makes major companies more competitive. In order to reduce the operating costs a form of collaborative relationships among delivery companies would be required. Keywords: fertilizer subsidy, incentive price, cotton sector in Mali, privatization subsidiary, competitiveness. [less ▲]

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See detailOverhanging Constraints in Addivitive Manufacturing Using Two Different Tools
Bauduin, Simon ULg; Collet, Maxime ULg; Duysinx, Pierre ULg

Poster (2016, August 23)

Topology optimization is widely used as a design tool for advanced application in mechanical, aerospace and automotive industries. This technique offers an optimal distribution of a predetermined amount ... [more ▼]

Topology optimization is widely used as a design tool for advanced application in mechanical, aerospace and automotive industries. This technique offers an optimal distribution of a predetermined amount of material in a given design space. In the last years, a lot of efforts has been invested into the development of high performance methods such as homogenization, SIMP or BESO. However as the state of the art in manufacturing experiences evolution, a coupling between topology optimization and additive manufacturing is needed. Additive manufacturing has numerous advantages that fits the characteristics of topology optimized designs. It can manufacture highly complex design without high cost increase and furthermore continuous density material of the SIMP method could be manufactured by lattice structures. With all the opportunities given by the additive manufacturing the urge to bind the last one to topology optimization is heavily required. Specific constraints related to manufacturing issues have to be taken into account such as the need of supports structures to ensure a good heat evacuation during the manufacturing process, as well as to hold up overhanging section. Some researches have been done to try to include this constraint in the optimization problem such as Leary and al or Andrew T. Gaynor. However this work focuses on 2 different methods (projection scheme and mechanical approach) to tackle the overhanging problem and compare them . [less ▲]

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