WORKSHOP 1 Detailing for Durability

Learning objective: to learn about energy standards and how to design advanced energy efficient building envelopes. Passive house principals and fundamentals on thermal, moisture issues, and air tightness will be covere

To federate pedagogical activities to set up an integrated project in mechatronics : report of innovation

La conception intégrée de systèmes combinant mécanique, génie électrique, informatique et automatique constitue une nouvelle discipline, la mécatronique, que la faculté des Sciences Appliquées de l'Université catholique de Louvain (UCL) a décidé depuis trois ans d'enseigner dans le cadre d'un nouveau diplôme en électromécanique, orientation mécatronique. Un des éléments originaux de cette formation est un projet intégré en mécatronique dont l'objectif est l'intégration au sein d'un même objet des différentes matières vues en cours. Cet article est un compte rendu d'une première expérience qui a conduit à la réalisation, par les étudiants de cette spécialité, de robots mobiles capables de se déplacer dans un labyrinthe pour y récupérer des balles et les placer dans des cibles déterminées

Multi-physics Modelling of a Compliant Humanoid Robot

In this paper, we discuss some very important features for getting exploitable simulation results for multibody systems, relying on the example of a humanoid robot. First, we provide a comparison of simulation speed and accuracy for kinematics modeling relying on relative vs. absolute coor- dinates. This choice is particularly critical for mechanisms with long serial chains (e.g. legs and arms). Compliance in the robot actuation chain is also critical to enhance the robot safety and en- ergy efficiency, but makes the simulator more sensitive to modeling errors. Therefore, our second contribution is to derive the full electro-mechanical model of the inner dynamics of the compliant actuators embedded in our robot. Finally, we report our reasoning for choosing an appropriate contact library. The recommended solution is to couple our simulator with an open-source contact library offering both accurate and fast full-body contact modeling

Peptide exchange on MHC-I by TAPBPR is driven by a negative allostery release cycle.

Chaperones TAPBPR and tapasin associate with class I major histocompatibility complexes (MHC-I) to promote optimization (editing) of peptide cargo. Here, we use solution NMR to investigate the mechanism of peptide exchange. We identify TAPBPR-induced conformational changes on conserved MHC-I molecular surfaces, consistent with our independently determined X-ray structure of the complex. Dynamics present in the empty MHC-I are stabilized by TAPBPR and become progressively dampened with increasing peptide occupancy. Incoming peptides are recognized according to the global stability of the final pMHC-I product and anneal in a native-like conformation to be edited by TAPBPR. Our results demonstrate an inverse relationship between MHC-I peptide occupancy and TAPBPR binding affinity, wherein the lifetime and structural features of transiently bound peptides control the regulation of a conformational switch located near the TAPBPR binding site, which triggers TAPBPR release. These results suggest a similar mechanism for the function of tapasin in the peptide-loading complex

Expression proteomics of UPF1 knockdown in HeLa cells reveals autoregulation of hnRNP A2/B1 mediated by alternative splicing resulting in nonsense-mediated mRNA decay

BACKGROUND: In addition to acting as an RNA quality control pathway, nonsense-mediated mRNA decay (NMD) plays roles in regulating normal gene expression. In particular, the extent to which alternative splicing is coupled to NMD and the roles of NMD in regulating uORF containing transcripts have been a matter of debate. RESULTS: In order to achieve a greater understanding of NMD regulated gene expression we used 2D-DiGE proteomics technology to examine the changes in protein expression induced in HeLa cells by UPF1 knockdown. QPCR based validation of the corresponding mRNAs, in response to both UPF1 knockdown and cycloheximide treatment, identified 17 bona fide NMD targets. Most of these were associated with bioinformatically predicted NMD activating features, predominantly upstream open reading frames (uORFs). Strikingly, however, the majority of transcripts up-regulated by UPF1 knockdown were either insensitive to, or even down-regulated by, cycloheximide treatment. Furthermore, the mRNA abundance of several down-regulated proteins failed to change upon UPF1 knockdown, indicating that UPF1`s role in regulating mRNA and protein abundance is more complex than previously appreciated. Among the bona fide NMD targets, we identified a highly conserved AS-NMD event within the 3` UTR of the HNRNPA2B1 gene. Overexpression of GFP tagged hnRNP A2 resulted in a decrease in endogenous hnRNP A2 and B1 mRNA with a concurrent increase in the NMD sensitive isoforms. CONCLUSIONS: Despite the large number of changes in protein expression upon UPF1 knockdown, a relatively small fraction of them can be directly attributed to the action of NMD on the corresponding mRNA. From amongst these we have identified a conserved AS-NMD event within HNRNPA2B1 that appears to mediate autoregulation of HNRNPA2B1 expression levels

Génération symbolique des équations du mouvement de systèmes multicorps et application dans le domaine ferroviaire

Doctorat en sciences appliquées -- UCL, 199

Optimal synthesis of mechanisms using time-varying dimensions and natural coordinates

This paper presents a simple approach to optimize the dimensions and the positions of 2D mechanisms for path or function-generator synthesis. The proposed method is particularly adapted to assembled mechanisms since time-varying dimensions always satisfy the assembly conditions which may represent a real difficulty when dealing with closed-loop mechanisms. The objective is to minimize the strain energy of the bars - considered as flexible - of the mechanism when this one follows perfectly the desired path. Two optimization strategies are developed and criticized. The first one is based on separated optimizations of design parameters and point coordinates. The second one is more global and is performed in two stages : multiple local synthesis are needed first to find the initial point coordinates, and then a global synthesis stage is undertaken to find both the best dimensions and coordinates. The use of natural coordinates is also particularly interesting since the only non linear functions to optimize are distance functions, and the objective function is rather well-conditioned for a gradient-based optimizer. The question of finding the global optimum is addressed and discussed. Since a standard genetic algorithm may fail to find it, a different approach is proposed: exploring the design space to find several local optima among which the designer will choose the most relevant one taking other design constraints into account. A simple technique is applied which consists in running multiple optimization processes starting from uniformly-distributed initial dimensions (full-factorial design of experiments) across the parameter space. Three applications are presented: a simple four-bar path synthesis to illustrate the optimization strategies, a four-bar steering linkage synthesis for function generation – Ackermann relation to highlight the limits of both strategies, and eventually a six-bar steering mechanism to explore the design space and find different local optima

Optimal synthesis of planar mechanisms via an extensible-link approach

This paper presents a novel approach to optimize the design of planar mechanisms with revolute joints for function-generation or path synthesis. The proposed method is based on the use of an extensible-link mechanism model whose strain energy is minimized to find the optimal rigid design. This enables us to get rid of assembling constraints and the use of natural coordinates makes the objective function simpler. The optimization strategy is divided into two stages: the first one relies on multiple partial optimizations and provides hot starting point for the second stage which involves all the variables and all the energy contributions. The question of finding the global optimum is reviewed. Instead, a simple algorithm is proposed to explore the design space and to find several local optima among which the designer may choose the best one taking other criteria into account (e.g. stiffness, collision, size,. . . ). Two applications are presented to illustrate the whole process

Prevalence, characteristics and impacts of urinary incontinence and other pelvic floor disorders in women with myotonic dystrophy type 1

La dystrophie myotonique de type 1 (DM1) est une maladie neuromusculaire multisystémique pouvant affecter les muscles lisses et striés. Quelques études ont rapporté des atteintes des muscles du plancher pelvien et pourraient ainsi avoir un impact important sur la fonction urogynécologique et anorectale. Une revue systématique a été réalisée dans le cadre de ce mémoire afin de documenter les conditions génito-urinaires et gastro-intestinales basses chez les personnes atteintes de DM1. Cette revue a permis de conclure que plusieurs études ont identifié des signes et symptômes variés associés à ces systèmes ; toutefois, peu d’études ont investigué ces désordres de manière spécifique, avec des outils standardisés. Cela résulte en des prévalences très variables et limite les conclusions sur la fréquence de ces symptômes. Les conditions génito-urinaires et gastro-intestinales sont souvent qualifiées comme des désordres du plancher pelvien étant donné l’implication des muscles du plancher pelvien. L’objectif principal de cette étude était de documenter la prévalence, les caractéristiques et les impacts de l’incontinence urinaire et des autres désordres du plancher pelvien chez les femmes atteintes de DM1. Les associations entre les désordres du plancher pelvien et le phénotype, en tenant compte de l’âge et la parité, ont été explorées. Une étude épidémiologique a été réalisée au Saguenay–Lac-St-Jean auprès de 80 femmes adultes atteintes de la DM1 à l’aide de questionnaires validés, notamment l’International Consultation Incontinence Questionnaire – Urinary Incontinence short form (ICIQ-UI-SF)), le Pelvic Floor Disorder Inventory (PFDI), et le Pelvic Floor Impact Questionnaire short form (PFIQ-SF). Les femmes étaient âgées entre 23 et 78 ans et présentaient une prévalence élevée d’incontinence urinaire (60%), d’incontinence anale (56.3%) et d’autres désordres du plancher pelvien, ce qui suggèrent une prévalence plus élevée que dans la population générale. Un large éventail de désordres est rapporté, ce qui est consistant avec la variabilité clinique bien connue en DM1. L’impact de ces désordres sur la participation et les domaines émotionnels étaient plus élevés pour les désordres colorectal-anales. À l’aide de régressions linéaires et logistiques, des associations avec les phénotypes pour le score total du ICIQ-UI-SF, la prévalence d’incontinence anale et la prévalence de douleur abdominale ont été détectées. Cette étude fournit des évidences concernant l’importance du dépistage de ces désordres dans un cadre clinique et la nécessité d’explorer les approches de traitement pour les femmes atteintes de DM1.Abstract: Myotonic dystrophy type 1 (DM1) is a neuromuscular multisystemic disease that can affect both smooth and striated muscles. Some studies have reported alteration to the pelvic floor muscles and could therefore have a significant impact on urogynecological and anorectal function. A systematic review was conducted as part of this thesis to document genitourinary and lower gastrointestinal conditions in people with DM1. This review concluded that several studies have identified various signs and symptoms associated with these systems; however, few studies have studied these disorders specifically, with standardized tools. This results in a wide range of prevalence and limits conclusions on the frequency of these symptoms. Genitourinary and gastrointestinal conditions are often referred to as pelvic floor disorders due to the involvement of the pelvic floor muscles. The main objective of this study was to document the prevalence, characteristics and impacts of urinary incontinence and other pelvic floor disorders in women with DM1. Associations between pelvic floor disorders and phenotypes, taking into account age and parity, were explored. An epidemiological study was carried out in Saguenay–Lac-St-Jean among 80 adult women with DM1 using validated questionnaires, in particular the International Consultation Incontinence Questionnaire – Urinary Incontinence short form (ICIQ-UI-SF)), the Pelvic Floor Disorder Inventory (PFDI), ant the Pelvic Floor Impact Questionnaire short form (PFIQ-SF). Women had a high prevalence of urinary incontinence (60%), anal incontinence (56.3%) and other pelvic floor disorders. A wide range of disorders are reported, consistent with the well-known clinical variability in DM1. The impact of these disorders on participation and emotional domains was higher for colorectal-anal disorders. Using linear and logistic regressions, associations with phenotypes for ICIQ-UI-SF total score, prevalence of anal incontinence and abdominal pain were detected. This study provides evidence regarding the importance of screening for these disorders in a clinical setting and the need to explore treatment approaches for women with DM1