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See detailLe décret décumul et le Parlement wallon
Grandjean, Geoffrey ULg; Janssens, Frédéric

in Administration Publique: Revue du Droit Public et des Sciences Administratives (2016), 2

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See detailLARCH: A package for estimating multinomial, nested, and cross-nested logit models that account for semi-aggregate data
Newman, Jeffrey; Lurkin, Virginie ULg; Garrow, Laurie

E-print/Working paper (2016)

We present a summary of important computational issues and opportunities that arise from the use of semi-aggregate data (where the explanatory data for choice scenarios are not necessarily unique for each ... [more ▼]

We present a summary of important computational issues and opportunities that arise from the use of semi-aggregate data (where the explanatory data for choice scenarios are not necessarily unique for each decision-maker) in discrete choice models. This data feature is commonly encountered with large transactional databases that have limited consumer information, such as itinerary choice modeling. We developed a software package called Larch, written in Python and C++, to take advantage of this kind of data to greatly speed the estimation of discrete choice model parameters. Benchmarking experiments against Stata (a commonly used commercial package) and Biogeme (a commonly used freeware package) based on an industry dataset for airline itinerary choice modeling applications shows that the size of the input estimation files are 50 to 100 times larger in Stata and Biogeme, respectively. Estimation times are also much faster in Larch; e.g., for a small itinerary choice problem, a multinomial logit model estimated in Larch converged in less than one second whereas the same model took almost 15 seconds in Stata and more than three minutes in Biogeme. For more complex discrete choice models, such as the ordered generalized extreme value model, estimation times were two seconds in Larch and four to five days in Biogeme. [less ▲]

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See detailSuperconductors used as trapped field magnets : investigation of hybrid structures combining superconducting and ferromagnetic materials
Vanderbemden, Philippe ULg; Fagnard, Jean-François ULg; Caps, Hervé ULg et al

Conference (2016, August 30)

In addition to their unique ability to carry electric currents without loss, superconductors are able to trap significant magnetic flux densities at low temperature. In so-called type-II irreversible ... [more ▼]

In addition to their unique ability to carry electric currents without loss, superconductors are able to trap significant magnetic flux densities at low temperature. In so-called type-II irreversible superconductors, these properties are due to the pinning of individual flux lines (vortices) by defects at the nanoscale level. In this talk the influence of pinning on the magnetic properties of bulk superconductors will be explained and illustrated, with the emphasis placed on how pinning can be exploited to produce “trapped field magnets” for practical applications. We will then show how the properties of these trapped field magnets are enhanced when superconductors (SC) are combined to soft ferromagnetic (FM) alloys [1,2]. In particular we investigate the properties of macroscopic FM/SC/FM structures where the superconductor is sandwiched between two ferromagnetic sections, one of each circular face. In particular we show how the properties of the whole structure is influenced by the saturation magnetization and the geometry of the ferromagnetic material. References: 1. M P Philippe, J-F Fagnard, S Kirsch, Z Xu, A R Dennis, Y H Shi, D A Cardwell, B Vanderheyden, and P Vanderbemden, Magnetic characterisation of large grain, bulk Y–Ba–Cu–O superconductor–soft ferromagnetic alloy hybrid structures. Physica C: 502 (2014) 20-30. 2. M P Philippe, M D Ainslie, L Wera, J-F Fagnard, A R Dennis, Y H Shi, D A Cardwell, B Vanderheyden, and P Vanderbemden, Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor. Superconductor Science and Technology: 28 (2015) 095008. [less ▲]

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See detailA Macro-Element Formulation and Solution Procedure for Shear Analysis of RC Deep Beams
Liu, Jian ULg; Mihaylov, Boyan ULg

in the 11th fib International PhD Symposium in Civil Engineering (2016, August 30)

This paper presents a computationally-effective macro element capable of predicting the complete shear response of RC deep beams in analogy with beam elements for slender beams. The element stems from a ... [more ▼]

This paper presents a computationally-effective macro element capable of predicting the complete shear response of RC deep beams in analogy with beam elements for slender beams. The element stems from a three-parameter kinematic theory (3PKT) for the shear strength and deformation capacity of deep beams subjected to double curvature. The macro element is composed of two rotational springs and one transverse spring to simulate the nonlinear flexural and shear behaviour of the shear span. The element has two nodes (end sections) with two DOFs per node, which enables it to be easily connected to other elements of the same or different types to model structures with deep beams. The numerical implementation of the element is based on the secant stiffness approach which provides robust convergence properties. Validation studies are performed by using thirteen tests from the literature showing excellent results for the complete shear response. The obtained peak load experimental-to-predicted ratios have an average of 1.10 with a coefficient of variation of 14.2%, while these values for the mid-span deflection are 1.16 and 17.0%. [less ▲]

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See detailEngineering resistance against CMD in model and Indian preferred cassava varieties
Vanderschuren, Hervé ULg

Scientific conference (2016, August 30)

NA

Detailed reference viewed: 6 (0 ULg)
See detailA hidden Markov model to estimate inbreeding from whole genome sequence data
Druet, Tom ULg; Gautier, Mathieu

Conference (2016, August 29)

Inbreeding results from the mating of related individuals and has negative consequence because it brings together deleterious variants in one individual. Inbreeding is associated with recessive diseases ... [more ▼]

Inbreeding results from the mating of related individuals and has negative consequence because it brings together deleterious variants in one individual. Inbreeding is associated with recessive diseases and reduced production or fitness. Until recently inbreeding was estimated with genealogical data, which have some limitations. Genomic estimates of inbreeding can now be obtained thanks to new technologies. Methods based on genomic relationships assume either that identical-by-state markers are identical-by-descent (IBD) or correct for the allele frequencies estimated in a « founder generation ». Similarly, with runs of homozygosity (ROH), the hypothesis is that stretches of homozygous markers longer than a determined threshold (measured in number of markers or in Mb) are IBD. Although sequencing data are more informative, most of the recent studies used genotyping data. Due to high genotyping errors rates with sequencing technologies, ROH are difficult to use on such data. We herein describe an original method to model inbreeding along chromosomes. It relies on a hidden Markov model that determines locally whether a segment is inbred and gives a measure of inbreeding's age. The method uses a function modeling the probability to observe a genotype in an inbred segments. It is well suited for sequencing data because the function incorporates genotyping errors and uncertainty associated with low or moderate coverage. We first determine the properties of our new method with different simulation scenarii. Then, we use it to estimate inbreeding in the Belgian Blue Beef cattle population with either genotyping arrays (of various densities) or whole genome sequencing data. The estimates will be compared to those obtained with other methods (pedigree, ROH, genomic relationship). Latest results will be presented. [less ▲]

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See detailPsychological transition and adjustment processes related to retirement: Influence on cognitive functioning
Grotz, Catherine ULg; Matharan, Fanny; Pérès, Karine et al

in Aging & Mental Health (2016)

Objective: To investigate the relationship between psychological transition and adjustment to retirement and cognitive performances in older adults. Methods: The study’s sample was taken from the Approche ... [more ▼]

Objective: To investigate the relationship between psychological transition and adjustment to retirement and cognitive performances in older adults. Methods: The study’s sample was taken from the Approche Multidisciplinaire Int egr ee cohort, a French prospective study of retirees from agriculture, aged 65 and over, living in rural settings in southwestern France. The cross-sectional analyses were conducted on a sample of 590 elderly people without dementia at baseline and for whom information on perception of the work setting, experience of the retirement transition and adaptation to retirement life (nine variables) as well as neuropsychological measures (global cognitive functioning, episodic memory, verbal fluency, attention and psychomotor speed) were available at first visit. Results: Multivariable linear regression analyses, including nine variables related to retirement and adjusted for potential confounding factors, indicated that three of them positive consideration of former work situation, development of new activities during retirement and good adaptation to free time were associated with better cognitive performances. Conclusions: We found that several factors proved to be determinants of good cognitive functioning at retirement and could serve as a basis for the development of more efficient intervention programs aimed at helping retirees to maintain good cognitive functioning after retirement. [less ▲]

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See detailPrecision synthesis of poly(ionic liqui)s in aqueous media by cobalt-mediated radical polymerization
Cordella, Daniela ULg

Doctoral thesis (2016)

Poly(ionic liquid)s (PILs) are a subclass of polyelectrolytes that gained an enabling role in many fields of polymer chemistry and material science. PILs combine the unique properties of ionic liquids ... [more ▼]

Poly(ionic liquid)s (PILs) are a subclass of polyelectrolytes that gained an enabling role in many fields of polymer chemistry and material science. PILs combine the unique properties of ionic liquids with the flexibility and properties of macromolecules, and provide novel attractive functions. Recently, the precision design of novel PILs by controlled/living polymerization (CLP) techniques was intensively searched for developing emerging applications, such as those based on the self-assembly of block copolymers (BCPs). Indeed, combining the physicochemical properties of PILs with the self-assembly of BCPs is a route to easily produce innovative functional nanostructures that have a huge potential for many applications, e.g. for electrochemical devices, gas membranes, nanostructures materials, etc. Among the panel of poly(ionic liquid)-based block copolymers (PIL BCPs) that is available, vinyl imidazolium-based derivatives are highly attractive due their high charge density, the possibility to easily tune their properties by the nature of the alkyl chain, etc. However, when this PhD thesis started, their synthesis by direct polymerization of N-vinyl imidazolium-type monomers was challenging for most of the CLP techniques. Only few examples of vinyl imidazolium-based PIL BCPs were accessible by Reversible Addition Fragmentation Transfer (RAFT) polymerization or Cobalt-Mediated Radical Polymerization (CMRP), and in organic media exclusively. The aim of this PhD thesis was to develop a controlled radical polymerization technique for N-vinyl imidazolium-type monomers in water that would facilitate the precision synthesis of PIL BCPs in this green solvent under non-demanding experimental conditions. Due to its compatibility to water and to its high versatility, the CMRP process was used for that purpose. The synthetic challenges that we address in this thesis are (1) to perform the CMRP of N-vinyl imidazolium type monomers in water, (2) to prepare hydrosoluble but also amphiphilic all PIL BCPs in this green solvent, and (3) to simplify the process to facilitate its scaling-up. The potential of the innovative PILs developed during this thesis was then explored for applications in energy (as solid electrolytes for battery applications) and environment (as antibacterial coatings/materials). [less ▲]

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See detailWill climate change affect insect pheromonal communication?
Boullis, Antoine ULg; Detrain, Claire; Francis, Frédéric ULg et al

in Current Opinion in Insect Science (2016)

Understanding how climate change will affect species interactions is a challenge for all branches of ecology. We have only limited understanding of how increasing temperature and atmospheric CO2 and O3 ... [more ▼]

Understanding how climate change will affect species interactions is a challenge for all branches of ecology. We have only limited understanding of how increasing temperature and atmospheric CO2 and O3 levels will affect pheromone-mediated communication among insects. Based on the existing literature, we suggest that the entire process of pheromonal communication, from production to behavioural response, is likely to be impacted by increases in temperature and modifications to atmospheric CO2 and O3 levels. We argue that insect species relying on long-range chemical signals will be most impacted, because these signals will likely suffer from longer exposure to oxidative gases during dispersal. We provide future directions for research programmes investigating the consequences of climate change on insect pheromonal communication. [less ▲]

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See detailTHE BEAT GENERATION Beat Generation - L’Anthologie Musicale - Hep Cats, Hipsters & Beatniks 1936-1962 (FREMEAUX & ASSOCIES)
Sacré, Robert ULg

E-print/Working paper (2016)

The Beat Generation - L’Anthologie Musicale - Compte rendu Hep Cats, Hipsters & Beatniks 1936-1962 FREMEAUX & ASSOCIES

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See detailHow reliable are the models to study recent climate change ? A study of heat/cold waves and radiative fluxes trends over 1900-2010 using the model MAR in Belgium
Wyard, Coraline ULg; Fettweis, Xavier ULg; Scholzen, Chloé ULg

Poster (2016, August 29)

This research aims to assess the ability of the regional climate model MAR ("Modèle Atmosphérique Régional") to reconstruct the observed twentieth century climatology of extreme events and solar radiation ... [more ▼]

This research aims to assess the ability of the regional climate model MAR ("Modèle Atmosphérique Régional") to reconstruct the observed twentieth century climatology of extreme events and solar radiation in Belgium, as a necessary condition for reliable future projections. Simulations were performed by forcing MAR with several reanalyses: the ERA40/ERA-Interim, the ERA-20C and the NCEP/NCAR-v1. The results suggests that increasing air temperature would have generated decreasing relative humidity which would have lead to a decrease in cloudiness and an increase in solar downward radiation. This research illustrates the dependency between RCMs and their forcings. The forcing reanalyses can generate divergent trends while contrary to Global Climate Models (GCM), the reanalyses assimilate observations and are supposed to represent the same climate. [less ▲]

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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 ▲]

Detailed reference viewed: 55 (16 ULg)