Effects of computing parameters and measurement locations on the estimation of 3D NPS in non-stationary MDCT images.

The goal of this study was to investigate the impact of computing parameters and the location of volumes of interest (VOI) on the calculation of 3D noise power spectrum (NPS) in order to determine an optimal set of computing parameters and propose a robust method for evaluating the noise properties of imaging systems. Noise stationarity in noise volumes acquired with a water phantom on a 128-MDCT and a 320-MDCT scanner were analyzed in the spatial domain in order to define locally stationary VOIs. The influence of the computing parameters in the 3D NPS measurement: the sampling distances bx,y,z and the VOI lengths Lx,y,z, the number of VOIs NVOI and the structured noise were investigated to minimize measurement errors. The effect of the VOI locations on the NPS was also investigated. Results showed that the noise (standard deviation) varies more in the r-direction (phantom radius) than z-direction plane. A 25 × 25 × 40 mm(3) VOI associated with DFOV = 200 mm (Lx,y,z = 64, bx,y = 0.391 mm with 512 × 512 matrix) and a first-order detrending method to reduce structured noise led to an accurate NPS estimation. NPS estimated from off centered small VOIs had a directional dependency contrary to NPS obtained from large VOIs located in the center of the volume or from small VOIs located on a concentric circle. This showed that the VOI size and location play a major role in the determination of NPS when images are not stationary. This study emphasizes the need for consistent measurement methods to assess and compare image quality in CT.

Evaluation of performance analysis software for Linux computing cluster

Tietokonejärjestelmän osien ja ohjelmistojen suorituskykymittauksista saadaan tietoa,jota voidaan käyttää suorituskyvyn parantamiseen ja laitteistohankintojen päätöksen tukena. Tässä työssä tutustutaan suorituskyvyn mittaamiseen ja mittausohjelmiin eli ns. benchmark-ohjelmistoihin. Työssä etsittiin ja arvioitiin eri tyyppisiä vapaasti saatavilla olevia benchmark-ohjelmia, jotka soveltuvat Linux-laskentaklusterin suorituskyvynanalysointiin. Benchmarkit ryhmiteltiin ja arvioitiin testaamalla niiden ominaisuuksia Linux-klusterissa. Työssä käsitellään myös mittausten tekemisen ja rinnakkaislaskennan haasteita. Benchmarkkeja löytyi moneen tarkoitukseen ja ne osoittautuivat laadultaan ja laajuudeltaan vaihteleviksi. Niitä on myös koottu ohjelmistopaketeiksi, jotta laitteiston suorituskyvystä saisi laajemman kuvan kuin mitä yhdellä ohjelmalla on mahdollista saada. Olennaista on ymmärtää nopeus, jolla dataa saadaan siirretyä prosessorille keskusmuistista, levyjärjestelmistä ja toisista laskentasolmuista. Tyypillinen benchmark-ohjelma sisältää paljon laskentaa tarvitsevan matemaattisen algoritmin, jota käytetään tieteellisissä ohjelmistoissa. Benchmarkista riippuen tulosten ymmärtäminen ja hyödyntäminen voi olla haasteellista.

Des cheminements sur la voie royale : une analyse sociologique des parcours de vie des normaliens-ne-s de Saint-Cloud, Fontenay-aux-Roses et Lyon (1981-1987)

Cette thèse est consacrée à l'analyse des parcours de vie d'un groupe d'anciens et anciennes élèves d'un établissement scolaire d'élite français (les Ecoles normales supérieures de Fontenay-aux-roses, Saint-Cloud et Lyon - promotions 1981-1987). A partir d'une approche longitudinale, son but est de montrer comment l'articulation entre la socialisation familiale, scolaire, professionnelle et conjugale participe à l'orientation progressive des parcours de vie des normalien-ne-s. Elle vise ainsi à remettre en question l'idée, largement répandue, selon laquelle l'intégration d'un cursus scolaire aussi sélectif et prestigieux que celui des ENS garantirait à Lou.te.s les élèves les mêmes chances d'accès aux positions dominantes de l'espace social. Alliant l'analyse de trois types de données (archives, questionnaires, entretiens), cette thèse met en évidence la manière dont inégalités relatives à l'origine sociale et au sexe se recomposent, une fois les portes de l'institution franchies. Elle montre que, dans un contexte socio-historique marqué par une forte expansion scolaire, il est plus que jamais nécessaire d'opérer une articulation systématique entre l'analyse des conditions sociales de réussite scolaire et l'analyse des conditions sociales d'exploitation des titres scolaires, afin de rendre compte des processus complexes de reproduction des inégalités et d'esquisser certaines de leur conditions de dépassement. Abstract: This thesis is dedicated to the life course analysis of alumni from one of the most prestigious French Grandes écoles (the Ecoles Normales Supérieures of Fontenay-aux- roses, Saint-Cloud and Lyon - classes of 1981.-1987). Through a longitudinal perspective, it aims to analyze how family, educational, professional and conjugal socialization processes combine to shape the life course of this particular group of graduates. The main goal of this research is to question the widespread belief that the French Grandes Ecoles guarantee automatic access to the very top of the professional and social hierarchy for all of their graduates. Based on a mixed methods research design (archive data, a questionnaire survey and semi-structured interviews), this thesis shows that, according to social origin and gender, ENS graduates actually adopt a diverse range of professional careers. It show how, in a socio-historical context characterized by a general increase in educational levels, any analysis of social inequalities should combine two levels of analysis: the social conditions of access to educational credentials, on the one hand, and the labor market value of formal qualifications, on the other hand. Our results suggest that the combined analysis of these two processes provide useful insight into the increasingly complex processes of social reproduction - and suggest fruitful perspectives for reducing some sources of inequality.

18/4/20, [avenue du Palais à] St Cloud, concours de patinettes à moteur, Myrtho Laverne [sur la machine] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 58923

18/4/20, [avenue du Palais à] St Cloud, concours de patinettes à moteur, Mistinguette [sur la machine] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 58924

St Cloud, 25/4/20, rugby, Stade français contre A.S. Bayonnaise : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59036

St Cloud, 25/4/20, rugby, Stade français contre A.S. Bayonnaise : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59040

St Cloud, 25/4/20, rugby, équipe Stade français : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59042

St Cloud, 25/4/20, rugby, équipe A.S. Bayonnaise : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59043

Coscheduling techniques and monitoring tools for non-dedicated cluster computing

Our efforts are directed towards the understanding of the coscheduling mechanism in a NOW system when a parallel job is executed jointly with local workloads, balancing parallel performance against the local interactive response. Explicit and implicit coscheduling techniques in a PVM-Linux NOW (or cluster) have been implemented. Furthermore, dynamic coscheduling remains an open question when parallel jobs are executed in a non-dedicated Cluster. A basis model for dynamic coscheduling in Cluster systems is presented in this paper. Also, one dynamic coscheduling algorithm for this model is proposed. The applicability of this algorithm has been proved and its performance analyzed by simulation. Finally, a new tool (named Monito) for monitoring the different queues of messages in such an environments is presented. The main aim of implementing this facility is to provide a mean of capturing the bottlenecks and overheads of the communication system in a PVM-Linux cluster.

Teaching fundamentals of computing theory: a constructivist approach

A Fundamentals of Computing Theory course involves different topics that are core to the Computer Science curricula and whose level of abstraction makes them difficult both to teach and to learn. Such difficulty stems from the complexity of the abstract notions involved and the required mathematical background. Surveys conducted among our students showed that many of them were applying some theoretical concepts mechanically rather than developing significant learning. This paper shows a number of didactic strategies that we introduced in the Fundamentals of Computing Theory curricula to cope with the above problem. The proposed strategies were based on a stronger use of technology and a constructivist approach. The final goal was to promote more significant learning of the course topics.