Continuity of the asymptotic shape of the supercritical contact process

We prove the continuity of the shape governing the asymptotic growth of the supercritical contact process in Z^d , with respect to the infection parameter. The proof is valid in any dimension d $\ge$ 1

The HyperBagGraph DataEdron: An Enriched Browsing Experience of Multimedia Datasets

Traditional verbatim browsers give back information in a linear way according to a ranking performed by a search engine that may not be optimal for the surfer. The latter may need to assess the pertinence of the information retrieved, particularly when s$\cdot$he wants to explore other facets of a multi-facetted information space. For instance, in a multimedia dataset different facets such as keywords, authors, publication category, organisations and figures can be of interest. The facet simultaneous visualisation can help to gain insights on the information retrieved and call for further searches. Facets are co-occurence networks, modeled by HyperBag-Graphs -- families of multisets -- and are in fact linked not only to the publication itself, but to any chosen reference. These references allow to navigate inside the dataset and perform visual queries. We explore here the case of scientific publications based on Arxiv searches.Comment: Extension of the hypergraph framework shortly presented in arXiv:1809.00164 (possible small overlaps); use the theoretical framework of hb-graphs presented in arXiv:1809.0019

The reform of European securities settlement systems : Towards an integrated financial market

The European Central Bank (ECB) will offer to banks in 2013 an european shared platform for securities settlement, named TARGET 2 Securities (T2S), in order to open the national financial markets. The financial crisis did not change the ECB agenda. This paper develops a spatial competition model to understand the impact of this new organisation on european post-trading services. We analyse the incentives of the Central Securities Depositaries (CSD) to move to T2S when they become competitors in the market for settlement services and remain in a monopoly position for depository services. Settlement and depository services are complementary goods, because banks have to pay for these two services to buy or sell a security. We show that such a reform should induce a decrease in the settlement price and more generally in post-trading prices, but that prices depend strongly on market organisation. Under certain conditions, partial adhesion would make prices increase. This configuration appears as a Nash equilibrium. As CSDs are free to adhere to T2S, the ECB might be forced to regulate.Post-trading organisation; securities settlement; depositary services; compatibility

Characterizing, Explaining and Valuing the Effective Use of an IT Artefact: A Field Study of Performance Management Information Systems in SMEs

Calls have been made for IS research to shift from the study of the use of IT artefacts to the study of their effective use. In seeking to provide added validity and relevance to the concept of effective use, we apply Burton-Jones and Grange’s theoretical framework to study the dimensions, contextual drivers and benefits of effective use. This is done through a field study of performance management information systems (PMIS) as used in 16 small and medium-sized enterprises (SMEs). In characterizing, contextualizing and valuing the effective use of a mission-critical IT artefact such as a PMIS, our results provide further empirical grounding and understanding of this complex yet under researched concept

Simple and complex motor skills in children with dyslexia and/or attention deficit/hyperactivity disorder : towards a unifying framework of sequential motor impairments in neurodevelopmental disorders

Les difficultés motrices sont de plus en plus rapportées à travers différentes maladies neurologiques incluant les troubles neurodéveloppementaux et les troubles neurodégénératifs. À partir de ces observations, des théories ont émergé et suggèrent que la co-occurrence de symptômes moteurs à travers les maladies neurologiques pourrait être un indicateur de mécanismes neurologiques aberrants communs aux différents troubles, ainsi qu’un indice de vulnérabilité cérébrale. La dyslexie et le trouble déficitaire de l’attention avec ou sans hyperactivité (TDA/H) sont deux troubles neurodéveloppementaux avec une prévalence élevée, qui sont associés à une multitude de difficultés cognitives et motrices, lesquelles se chevauchent fréquemment. L’existence simultanée de symptômes cognitifs est généralement bien reconnue et plusieurs auteurs ont développé des théories qui unifient les troubles neurodéveloppementaux afin d’expliquer cette co-occurrence. Cependant, moins d’accent a été mis sur la présence concomitante de difficultés motrices, possiblement en raison des résultats contradictoires dans la littérature en ce qui a trait à la présence des déficits moteurs. Ces divergences sont à leur tour probablement liées aux multiples outils utilisés pour l’évaluation des troubles moteurs. De plus, peu d’études ont exploré quelles composantes des habiletés motrices sont affectées de manière similaire chez les populations atteintes de dyslexie ou du TDA/H. L’objectif de cette thèse est de clarifier la co-occurrence de difficultés motrices chez des enfants et adolescents atteints d’une dyslexie ou d’un TDA/H en évaluant plusieurs composantes du fonctionnement moteur. De plus, la présence d’une association entre les symptômes cognitifs communs et les difficultés motrices est examinée afin d’appuyer l’hypothèse selon laquelle les mécanismes neurologiques atypiques qui sous-tendent les problèmes moteurs sont similaires dans les deux conditions (dyslexie et TDA/H). Cette thèse est composée de deux études empiriques. Le premier article évalue les habiletés motrices fines et globales avec des tâches qui varient entre la coordination simple et la coordination séquentielle plus complexe, et ce chez des enfants et adolescents qui ont reçu un diagnostic de dyslexie seulement, de TDA/H seulement ou un diagnostic comorbide. Les résultats suggèrent que les enfants avec une dyslexie et/ou un TDA/H présentent des difficultés motrices co-occurrentes en coordination unimanuelle et bimanuelle séquentielle en comparaison à des enfants qui ont un développement typique. Par ailleurs, la vitesse motrice simple est préservée chez ces premiers. De plus, les enfants avec un TDA/H seulement ont des difficultés plus prononcées sur une tâche de coordination bimanuelle asynchronisée et ils obtiennent des résultats déficitaires sur une tâche de dextérité manuelle. Ces résultats suggèrent que les enfants avec un TDA/H ont des difficultés motrices plus sévères et plus étendues. Le deuxième article explore la relation entre les habiletés cognitives et les difficultés en motricité séquentielle chez les enfants avec une dyslexie et/ou un TDA/H. Les résultats indiquent que les habiletés communes en mémoire de travail visuelle et en fluence mathématique sont des prédicteurs des difficultés motrices, sans différentiation entre les groupes. Toutefois, une exception a été observée chez le groupe TDA/H pour lequel les habiletés en fluence mathématique ne contribuent pas significativement aux habiletés bimanuelles synchronisées. De plus, les symptômes diagnostiques de chaque syndrome, soit la lecture en dyslexie et l’inattention dans le TDAH, ne contribuent pas significativement à prédire la performance motrice. Les résultats appuient la notion de la présence de mécanismes neurologiques communs qui sous-tendent ces difficultés motrices analogues. Cette thèse suggère que les enfants avec une dyslexie et/ou un TDA/H présentent fréquemment des difficultés communes en motricité séquentielle. À notre connaissance, ces résultats sont parmi les premiers à suggérer que la dyslexie et le TDA/H présentent une relation similaire entre leurs symptômes cognitifs et moteurs. Ces conclusions appuient l’hypothèse selon laquelle la dyslexie et le TDA/H sont différentes facettes d’une atypie développementale commune et que des difficultés en motricité séquentielle pourraient être un indicateur d’une vulnérabilité cérébrale. Ces résultats fournissent des informations importantes qui permettraient de guider l’évaluation et le dépistage des troubles neurodéveloppementaux. Ils encouragent également le développement et la mise en place d’interventions motrices qui intègrent la planification motrice séquentielle.There is growing evidence that motor abnormalities are present in many neurological illnesses, ranging from neurodevelopmental disorders to neurodegenerative dementia. Theories have emerged suggesting that co-occurring motor impairments across disorders can be indicators of a vulnerable brain state and common aberrant underlying mechanisms. Dyslexia and Attention Deficit disorder with or without hyperactivity (AD) are two prevalent neurodevelopmental disorders and are associated with a collection of cognitive and motor symptoms that often co-occur. The co-occurrence of cognitive symptoms across dyslexia and AD is generally accepted and authors have developed unifying frameworks to better understand accumulating evidence of overlapping symptoms. However, less emphasis has been placed on co-occurring motor impairments, in part due to the inconsistency of findings associated with the many different assessment tools used across studies. In addition, few studies have explored what components of motor abilities are similarly impaired in both disorders. The objective of the current thesis is to clarify the presence of co-occurring motor difficulties in dyslexia and AD by assessing a variety of abilities associated with motor functioning. In addition, the relationship between co-occurring cognitive symptoms and motor difficulties is examined across both disorders to support the putative presence of a common aberrant mechanism that may underlie co-occurring motor weaknesses in dyslexia and AD. The thesis is comprised of two empirical articles. The first paper assesses fine and gross motor abilities that range from simple to complex sequential coordination, in children with dyslexia only, AD only, and both disorders (Combo). Results suggest that children with dyslexia and/or AD have co-occurring difficulties compared to their typically developing peers on unimanual and bimanual sequential coordination in the presence of preserved simple motor speed. In addition, children with AD have more severe problems in complex bimanual out-of-phase coordination and are impaired on measures of dexterity. These results suggest that children with AD may have weaknesses on a wider range of motor abilities and have more profound bimanual coordination difficulties. The second paper examines the relationship between cognitive abilities and co-occurring sequential motor difficulties in dyslexia and AD. Capabilities in visual working memory and math fluency were found to be significant predictors of motor abilities without differentiation between disorders, with one exception by which math fluency did not contribute to performance on bimanual in-phase coordination in the AD group. Moreover, the distinctive symptoms of reading in dyslexia and inattention in AD did not contribute significantly to sequential motor performance. The results suggest that the pattern of motor difficulties is similar in dyslexia and AD, and support the presence of common mechanisms that underlie co-occurring motor weaknesses. We suggest that dyslexia and AD often have co-occurring sequential motor difficulties, and to our knowledge these findings are among the first to show a shared relationship between cognitive abilities and sequential motor weaknesses. The findings support the idea that dyslexia and AD are different facets of a common atypical development and that shared sequential motor difficulties are indicators of a vulnerable brain state. The findings provide important information to help guide assessment and early screening of neurodevelopmental disorders, as well as encourage the development and application of motor intervention programs that integrate sequential motor planning