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See detailAccounting for price endogeneity in airline itinerary choice models
Lurkin, Virginie ULg

Scientific conference (2016, May 26)

This study formulates an itinerary choice model that is consistent with those used by industry and corrects for price endogeneity using a control function that uses several types of instrumental variables ... [more ▼]

This study formulates an itinerary choice model that is consistent with those used by industry and corrects for price endogeneity using a control function that uses several types of instrumental variables. We estimate our models using database of more than 3 million tickets provided by the Airlines Reporting Corporation. Results based on Continental U.S. markets for May 2013 departures show that models that fail to account for price endogeneity overestimate customers' value of time and result in biased price estimates and incorrect pricing recommendations. Extensions to advanced discrete choice models show the importance of accounting for inter-alternative substitution for products that share similar departure times. [less ▲]

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See detailUnderstanding the effect of thermal treatments on the ductility of LBM AlSi10Mg
Mertens, Anne ULg; Dedry, Olivier ULg; Lecomte-Beckers, Jacqueline ULg et al

Conference (2016, May 26)

This communication reviews the additive manufacturing activities of the MMS Unit, University of Liège, with a particular focus on the study of post-processing treatments of Al alloy AlSi10Mg. Al alloy ... [more ▼]

This communication reviews the additive manufacturing activities of the MMS Unit, University of Liège, with a particular focus on the study of post-processing treatments of Al alloy AlSi10Mg. Al alloy AlSi10Mg processed by Laser Beam Melting (LBM) exhibits a much finer microstructure than its cast counterpart due to the ultra-fast cooling rates imposed in the LBM process. One important consequence of this microstructural refinement is that a classical T6 age hardening heat treatment will not have the same effect on LBM AlSi10Mg when compared with cast AlSi10Mg. Indeed, a previous study by the present authors has shown that heat treating LBM AlSi10Mg at 510°C for 6 hours followed by a second isothermal hold at 170°C for 6 hours brought a marked improvement of the yield stress by 30% and of the elongation at break by 220%. However, this was achieved at the expense of a decrease in both hardness and ultimate tensile strength. A better understanding of the underlying phenomena is needed in order to optimize the heat treatment of LBM AlSi10Mg. The present work hence aims at investigating in more depth the mechanical and microstructural evolution induced upon heat treating LBM AlSi10Mg. [less ▲]

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See detailMaster equation with quantized atomic motion including dipole-dipole interactions
Damanet, François ULg; Braun, Daniel; Martin, John ULg

Scientific conference (2016, May 26)

We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion [1]. Our equation provides a unifying ... [more ▼]

We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion [1]. Our equation provides a unifying picture of the consequences of recoil and in- distinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics, and is relevant for experiments with ultracold trapped atoms. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, and we find analytical formulas for a number of relevant states (Gaussian states, Fock states and thermal states). In particular, we show that the dipole-dipole interactions and cooperative photon emission can be modulated through the external state of motion. The effects predicted should be experimen- tally observable with Rydberg atoms [2]. [1] F. Damanet, D. Braun, and J. Martin, arXiv:1512.06676v2. [2] K. Afrousheh, P. Bohlouli-Zanjani, D. Vagale, A. Mugford, M. Fedorov, and J. D. D. Martin, Phys. Rev. Lett. 93, 233001 (2004) [less ▲]

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See detailLa médiation du média : adresse au lecteur, positions, dispositions
Servais, Christine ULg

Conference (2016, May 26)

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See detailEntre Rome, Bruxelles et l’Espagne : le confesseur du gouverneur-général, quelles loyautés ?
Pirlet, Pierre-François ULg

Conference (2016, May 26)

Les Pays-Bas catholiques de la première moitié du XVIIe siècle constituent un ensemble politique placés sous la direction d'un gouverneur-général de sang royal ou issu de la haute noblesse hispanique. La ... [more ▼]

Les Pays-Bas catholiques de la première moitié du XVIIe siècle constituent un ensemble politique placés sous la direction d'un gouverneur-général de sang royal ou issu de la haute noblesse hispanique. La cour de ce Prince est organisée sur le modèle madrilène : il est ainsi assisté par un confesseur particulier, choisi par le gouvernement royal pour ses qualités et pour son appartenance à l'un ou l'autre ordre religieux. Les religieux successifs qui occupent la charge font l'objet d'une attention soutenue de la part de différents acteurs politiques : le gouverneur-général lui-même, les courtisans bruxellois, le gouvernement royal, les ordres religieux et la papauté observent avec attention l'action de ces confesseurs. La vision qu'a Rome de ces clercs est celle d'alliés objectifs. Il est entendu que ceux-ci doivent naturellement assister le nonce en toute occasion et contribuer à asseoir la politique romaine en terres habsbourgeoises. Pourtant, à Bruxelles, les principaux intéressés ne suivent pas assidûment cette ligne directrice. Ma communication proposera d'étudier, sur la base de sources issues des Archives générales du Royaume de Belgique et de l'Archivo General de Simancas, l'attitude d'une série de confesseurs princiers actifs dans la grande première moitié du XVIIe siècle face aux attentes de la papauté et de ses représentants dans le but de comprendre dans quelle mesure ce clerc contribua à – ou se tint éloigné de – la politique telle que voulue depuis Rome. Je tâcherai également de recenser et de comprendre les loyautés – à Madrid, à Bruxelles et à Rome – conditionnant l'action de ce religieux. [less ▲]

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See detailEntre Rome, Bruxelles et l’Espagne. Une légation au service de la Monarchie de Philippe II
Regibeau, Julien ULg

Conference (2016, May 26)

La légation des Pays-Bas espagnols et de la Franche-Comté près le Saint-Siège au temps de l’agent Laurent du Blioul (1573-1598) n’a jamais véritablement rencontré l’intérêt des historiens. Cela est ... [more ▼]

La légation des Pays-Bas espagnols et de la Franche-Comté près le Saint-Siège au temps de l’agent Laurent du Blioul (1573-1598) n’a jamais véritablement rencontré l’intérêt des historiens. Cela est certainement dû à son manque d’envergure apparent. En effet, elle est, à cette époque, soumise à l’ambassadeur espagnol de Philippe II à Rome et la marge de manœuvre de son agent semble réduite au suivi technique des affaires ecclésiastiques des pays de par-deçà et de par-delà défendues devant la Curie. Une analyse sociopolitique de l’institution permet cependant de nuancer le propos. En dégageant la place que la légation occuperait au sein des puissants réseaux de pouvoir romains de la Monarchie, on constate en effet que celle-ci est loin d’être marginalisée. Au contraire, à travers l’action de son agent, elle est capable d’utiliser mais aussi d’entretenir et d’accroitre l’influence que la royauté exerce sur la ville. Sachant employer efficacement les nombreuses ressources exogènes qu’elle a à sa disposition, l’institution n’apparait alors plus comme le reflet d’une décadence diplomatique des Pays-Bas qui découlerait de l’éclatement et de l’enlisement de la Révolte. Au contraire, elle trouve sa place dans une certaine logique d’incorporation inhérente à la monarchie de Philippe II. Après quelques considérations autour des missions de la légation, cette communication se concentrera avant tout sur le rôle de son agent, Laurent du Blioul. Membre d’une dynastie de gens de robe au service de la maison d’Autriche depuis la fin du XVe siècle, il conserve un souvenir vivace de ces liens, vecteurs de prestige et d’ascension sociale. Nous montrerons en quoi ce service implique des liens d’obligations réciproques entre les du Blioul et leur souverain. [less ▲]

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See detailBrain breaks in the classroom. An example of implementation in Belgium
Cloes, Marc ULg; Cloes, Stéphanie

Conference (2016, May 26)

School is identified as the main pillar of the fight against sedentariness in youth. Several models of active schools have been described in the literature and, under the umbrella of the school policy ... [more ▼]

School is identified as the main pillar of the fight against sedentariness in youth. Several models of active schools have been described in the literature and, under the umbrella of the school policy enhancing physical activity (PA), five main dimensions can be identified (Physical education, Active transportation, Life environment, Sport at school, PA in the classroom). This underlines that, if the PE teacher is considered as the corner stone of the PA promotion at school, (s)he is not alone to create the conditions aiming to permit to the children to reach the PA level recommended daily. Integrating more PA in the classroom seems to be a promising approach for children lifestyle as well as for their overall learning. Worldwide, initiatives are proposed in order to convince classroom teachers to integrate more often PA in their educational activities. Nowadays, it seems determining to share experiences in order to identify good practices and solutions to the current problems that teachers can encountered on the field. The goal of this presentation is to illustrate two concrete examples of projects implemented in primary schools in Wallonia, Belgium. We will describe the teaching context as well as the main findings provided by a systematic data analysis conducted during these experiments. The first study focused on three classes proposing Brain Breaks (BB) videos during a 10 weeks period. The attitude of the pupils and the teaching staff opinions were analyzed. In the second study, varied PA breaks (BB video, games, and video developed by the pupils) were proposed during periods of two to four weeks. Data from participant observation and questionnaires were used. In both studies, findings support the planning of PA during classroom. Even if more controlled research designs would be necessary in order to determine the evidence of the results, we can state that practitioners and children involved in the projects showed really positive reactions about these opportunities to be more active. [less ▲]

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See detailRedrawing Comics into the Graphic Novel: the Historiography of Comics, Canonization, and Authors’ Histories of the Medium
Crucifix, Benoît ULg

Conference (2016, May 26)

The development of comics studies in the United States has been linked to the institutionalization of the ‘graphic novel’ as a ‘literary’ subset of comics deemed worthy of academic attention. Several ... [more ▼]

The development of comics studies in the United States has been linked to the institutionalization of the ‘graphic novel’ as a ‘literary’ subset of comics deemed worthy of academic attention. Several voices in North-America are now challenging the need for canon formation by arguing for other approaches to the historiography of comics beyond the graphic novel. Histories and definitions, however, as Thierry Smolderen argues, are not only written by scholars, but generated by a multiplicity of social groups actively participating in the ongoing negotiation of what the medium ‘is’. Drawing on these recent trends, I will engage in a disciplinary reflection on the historiography of comics by focusing on authors' histories of the medium. Cartoonists themselves indeed act as comics historians: suffice to think of Jules Feiffer's pioneering The Great Comic Book Heroes (1965). ‘Graphic novelists’ as Chris Ware, Art Spiegelman, Seth or Daniel Clowes have been deeply engaged in recovering the past of comics in their works as well as in essays, reprints, or exhibitions. These histories are fragmentary, emotionally charged and at times anachronistic, but they complicate teleological accounts of the graphic novel, disrupting the academic canon. Confronting this perspective with recent insights in literary historiography, I will attempt to examine some of the specific epistemological issues raised by cartoonists' histories of comics in their divergence or convergence with other historiographic trends such as fanzines and academic research. [less ▲]

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See detailDESIGN OF HIGH-AFFINITY LIGANDS FOR THE BENZOTHIADIAZINE ALLOSTERIC BINDING SITE OF THE AMPA RECEPTORS
Drapier, Thomas ULg; Geubelle, Pierre ULg; Bouckaert, Charlotte et al

Poster (2016, May 26)

L-glutamic acid is the major excitatory neurotransmitter in the brain. It exerts its effects through metabotropic and ionotropic receptors. Among the latter, three subtypes have been identified: NMDA ... [more ▼]

L-glutamic acid is the major excitatory neurotransmitter in the brain. It exerts its effects through metabotropic and ionotropic receptors. Among the latter, three subtypes have been identified: NMDA, AMPA and KA receptors. It is now well established that a deficit in glutamatergic signaling may be responsible for neurological disorders such as mild cognitive impairment, schizophrenia, depression, and ADHD. Enhancement of the signal through positive allosteric modulators of AMPA receptors might be a therapeutic issue for these diseases. These compounds are expected to exert a fine tuning of the signal. Since they require the presence of the endogenous ligand to be active, they are expected to induce less toxicity than agonists. In this context, based on the structure of known allosteric modulators of AMPA receptors such as cyclothiazide and IDRA 21, the Laboratory of Medicinal Chemistry (University of Liège) has developed a series of 1,2,4-benzothiadiazine 1,1-dioxides with high potency as AMPA receptor potentiators. Crystallographic data obtained by the Department of Drug Design and Pharmacology (University of Copenhagen) highlighted those potentiators bind to two contiguous sites at the dimer interface of the ligand binding domain (LBD) of the AMPA receptor1,2. Based on these data, we may expect that the synthesis of dimeric molecules could lead to further improvement in affinity and activity. This assumption was reinforced by docking experiments conducted with virtual examples of dimeric compounds on the GluA2-LBD (collaboration with NAMEDIC). The present work is thus focusing on the preparation of a family of dimeric benzothiadiazine dioxides. Moreover, in collaboration with GIGA-Molecular Pharmacology, we are developing a pharmacological in vitro assay based on the measurement of Ca2+ inflow through a fluorimetric method. This medium-throughput screening will enable the characterization of our new compounds and the validation of our working hypothesis. [less ▲]

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See detailUse of Estetrol with other Steroids for Attenuation of Neonatal Hypoxic-Ischemic brain injury:to combine or not to combine?
Tskitishvili, Ekaterine ULg; Pequeux, Christel ULg; Munaut, Carine ULg et al

in Oncotarget (2016)

Estetrol (E4), estradiol (E2) and progesterone (P4) have important antioxidative and neuroprotective effects in neuronal system. We aimed to study the consequence of combined steroid therapy in neonatal ... [more ▼]

Estetrol (E4), estradiol (E2) and progesterone (P4) have important antioxidative and neuroprotective effects in neuronal system. We aimed to study the consequence of combined steroid therapy in neonatal hypoxic-ischemic encephalopathy (HIE). In vitro the effect of E4 combined with other steroids on oxidative stress and the cell viability in primary hippocampal cultures was evaluated by lactate dehydrogenase and cell survival assays. In vivo neuroprotective and therapeutic efficacy of E4 combined with other steroids was studied in HIE model of immature rats. The rat pups rectal temperature, body and brain weights were evaluated. The hippocampus and the cortex were investigated by histo/immunohistochemistry: intact cell number counting, expressions of markers for early gray matter lose, neuro- and angiogenesis were studied. Glial fibrillary acidic protein was evaluated by ELISA in blood samples. In vitro E4 and combinations of high doses of E4 with P4 and/or E2 significantly diminished the LDH activity and upregulated the cell survival. In vivo pretreatment or treatment by different combinations of E4 with other steroids had unalike effects on body and brain weight, neuro- and angiogenesis, and GFAP expression in blood. The combined use of E4 with other steroids has no benefit over the single use of E4. [less ▲]

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See detailNumerical Modeling and Experimental Identification of Mistuned Multi-Stage Bladed Assemblies
Nyssen, Florence ULg

Doctoral thesis (2016)

In turbomachinery, low pressure compressors are composed of a succession of bladed disks. To reduce the mass and increase the performance of the aircraft engines, one-piece multi-stage units of bladed ... [more ▼]

In turbomachinery, low pressure compressors are composed of a succession of bladed disks. To reduce the mass and increase the performance of the aircraft engines, one-piece multi-stage units of bladed disks have been recently developed. But these one-piece technologies are challenging for the mechanical design due to exacerbated effects of mistuning (i.e., mode localization and forced response amplification). In the thesis, an experimental method for the identification of mistuning in multi-stage bladed structures is proposed and validated. Numerical modeling methods are proposed to reduce computational times for the statistical predictions of the forced response amplification. A characterization of the interstage coupling is performed and a criterion is proposed to predict in advance if a multi-stage analysis is necessary. [less ▲]

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See detailIn situ and laboratory mechanical characterization of a loess sequence from Middle Belgium
Delvoie, Simon ULg; Charlier, Robert ULg; Collin, Frédéric ULg

Conference (2016, May 25)

A 10 m thick loess (aeolian silt) layer located beside the Romont quarry (Eben-Emael, Middle Belgium) has been investigated in order to characterize the mechanical behaviour of the silty material. Cone ... [more ▼]

A 10 m thick loess (aeolian silt) layer located beside the Romont quarry (Eben-Emael, Middle Belgium) has been investigated in order to characterize the mechanical behaviour of the silty material. Cone penetration tests (CPT) have been performed with different cones (M1-type, M2-type and electric) in order to evaluate the influence of the cone on the mechanical behaviour interpretation. Concurrently, laboratory tests have been performed on undisturbed samples from core drillings. Laboratory tests consist of a physical characterization (grain size distribution, Atterberg limits) and a mechanical characterization (oedometer tests). This comprehensive investigation study focuses on the comparison of the loess characterization between in situ and laboratory approaches. CPT-based soil behaviour type charts are analyzed and compared with the Unified Soil Classification System. Many relations also exist in the literature between parameters obtained from CPT results and from laboratory tests. The study explores the existing relations between the cone resistance and the oedometer constrained modulus in order to verify the related coefficients proposed in the literature for silty material. [less ▲]

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See detailDenCity: Zero Energy Light Weight Construction Households for Urban Densification
Mahmoud, Mohamed ULg; Attia, Shady ULg

Scientific conference (2016, May 25)

This paper is a part of an ongoing research in the field of sustainable urban densification through providing innovative solutions for zero energy light weight construction. The focus aim of this research ... [more ▼]

This paper is a part of an ongoing research in the field of sustainable urban densification through providing innovative solutions for zero energy light weight construction. The focus aim of this research is to identify the gaps in the construction solutions for roof stacking, to feed in the innovation pipeline of the European construction landscape in the coming years. This paper presents a comprehensive review of different case studies and efforts in the field of roof raising and its repetition potentials. Based on a structured review, 8 different cases from three different European countries were sorted, placing a variety of methods in comparison with each other. The main contribution of this review lies in the analyses of the existing information in this field and the classification of the different validated methods and approaches that has been used. Finally, despite the existing challenges, it was found that the concept of roof stacking can be widely spread and applied in different contexts. Future research is going to investigate possible solution and to formulate structured scientific approaches to widen its application. [less ▲]

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See detailÀ la redécouverte d’une série d’autels égyptisants romains
Veymiers, Richard ULg

Conference (2016, May 25)

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See detailLes problématiques de la rénovation du stock bâti dans la ville de demain : résultats d’une étude initiale en Belgique.
Ruellan, Guirec ULg; Attia, Shady ULg

Scientific conference (2016, May 25)

Pour atteindre les objectifs énergétiques de l’Union Européenne pour 2050, et plus largement les objectifs fixés à la dernière COP, le secteur de la construction et de l’habitat doit opérer sa mue vers un ... [more ▼]

Pour atteindre les objectifs énergétiques de l’Union Européenne pour 2050, et plus largement les objectifs fixés à la dernière COP, le secteur de la construction et de l’habitat doit opérer sa mue vers un modèle plus durable. En Belgique, cela passe par la rénovation et l’amélioration des performances du stock bâti existant. La présente étude porte sur l’identification des différents enjeux (environnementaux, économiques et sociaux) liées à la rénovation en Belgique et tente d’objectiver les barrières (de financement, de communication et de réglementation) à une augmentation du taux de rénovation, à travers une revue de littérature des différentes études et projets portant sur ce domaine en Belgique. Ces résultats initiaux devront permettre ultérieurement la conduite des recherches approfondies visant à la modélisation des effets de plusieurs stratégies possibles d’augmentation du taux de rénovation. [less ▲]

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See detailPériurbanisation et efficacité de l'usage de la ressource foncière à Kinshasa
Messina Ndzomo, Jean Pierre ULg; Mate, Jean-Pierre; Halleux, Jean-Marie ULg

Conference (2016, May 25)

Kinshasa est la capitale de la République Démocratique du Congo et la plus grande ville francophone d’Afrique subsaharienne sur le plan démographique et spatial. Alors que Kinshasa comptait 400 000 ... [more ▼]

Kinshasa est la capitale de la République Démocratique du Congo et la plus grande ville francophone d’Afrique subsaharienne sur le plan démographique et spatial. Alors que Kinshasa comptait 400 000 habitants en 1960, son volume de population est actuellement estimé entre 8 et 12 millions d’habitants. La forte croissance démographique de cette ville, dont le taux de progression se situerait autour de 4 % depuis 2000, justifie sa dynamique spatiale. La conséquence immédiate est l’étalement urbain et une urbanisation non maitrisée favorisés par l’accroissement de la demande en logement. La crise du logement est de plus en plus forte dans un contexte marqué par une faiblesse des politiques publiques sur l’habitat. La géographie urbaine de Kinshasa connait, en conséquence, de profondes mutations depuis quelques décennies, des quartiers centraux et péricentraux se densifient et des lotissements périurbains colonisent de vastes territoires. Plus spécifiquement la périurbanisation, phénomène d’étalement des villes, s’y impose très largement. La présente communication porte sur notre projet de thèse qui cherche à comprendre les relations entre les mécanismes fonciers et la production de l’urbanisation à Kinshasa. De manière synthétique, la recherche est basée sur l’hypothèse que l’urbanisation de Kinshasa est spatialement inefficace. Elle est de plus en plus éloignée du centre-ville et des axes principaux et colonise vraisemblablement les zones physiquement inappropriées à l’urbanisation. Il ressort de notre revue de la littérature que l’urbanisation de Kinshasa résulte de dynamiques variées. D’un côté, nous assistons à une très forte densification de certains quartiers. D’un autre côté, la ville connaît un étalement urbain qui s’accompagne du développement de quartiers périphériques à faible densité. La première partie de notre travail vise à quantifier le phénomène d’urbanisation à Kinshasa. Cette quantification sera établie sur base des sources statistiques disponibles. Elle mobilisera également les techniques de la télédétection, afin de suivre l’évolution spatiale de la croissance urbaine. Cette partie du travail permettra notamment de vérifier l’hypothèse consistant à considérer que la croissance de Kinshasa oppose et conjugue des dynamiques de forte densification à des dynamiques d’étalement urbain. C’est cette partie du travail qui devra notamment permettre de vérifier si les logiques d’étalement urbain engendrent un gaspillage de ressources foncières préjudiciables aux activités de l’agriculture (péri) urbaine et au maintien du couvert forestier. La seconde partie de notre travail consistera dans le développement d’enquêtes. Des enquêtes seront menées auprès de deux publics cibles : d’une part, les acteurs actifs dans la production urbaine et, d’autre part, les populations. Enquêter auprès des acteurs de la production urbaine (architectes, promoteurs, planificateurs, chefs traditionnels, administrations : urbanisme, habitat et affaires foncières,…) devra permettre une compréhension des mécanismes fonciers et immobiliers qui alimentent la production du logement à Kinshasa (nous pensons en particulier au rôle des prix et des valeurs sur les phénomènes de densification et d’étalement urbain). En parallèle, enquêter auprès des populations visera à évaluer le niveau d’efficacité spatiale de l’urbanisation mise en place. Développer ce sujet de l’efficacité spatiale consistera à vérifier si, d’un côté, la densification n’atteint pas des niveaux critiques et si, d’un autre côté, l’étalement ne conduit pas à des déplacements – et donc à des coûts de transport – inutiles. [less ▲]

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See detailSemiparametric frailty model for clustered interval-censored data
Cetinyürek, Aysun ULg; Lambert, Philippe ULg

Report (2016)

The shared frailty model is a popular tool to analyze correlated right-censored time-to-event data. In the shared frailty model, the latent frailty is assumed to be shared by the members of a cluster and ... [more ▼]

The shared frailty model is a popular tool to analyze correlated right-censored time-to-event data. In the shared frailty model, the latent frailty is assumed to be shared by the members of a cluster and is assigned a parametric distribution, typically a gamma distribution due to its conjugacy. In the case of interval-censored time-to-event data, the inclusion of frailties results in complicated intractable likelihoods. Here, we propose a exible frailty model for analyzing such data by assuming a smooth semiparametric form for the conditional time-to-event distribution and a parametric or a exible form for the frailty distribution. The results of a simulation study suggest that the estimation of regression parameters is robust to misspeci cation of the frailty distribution (even when the frailty distribution is multimodal or skewed). Given su ciently large sample sizes and number of clusters, the exible approach produces smooth and accurate posterior estimates for the baseline survival function and for the frailty density, and can correctly detect and identify unusual frailty density forms. The methodology is illustrated using dental data from the Signal Tandmobiel® Study. [less ▲]

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