New Internal Stress Driven on-Chip Micromachines for Extracting Mechanical Properties of Thin Films

A new concept of micromachines has been developed for measuring the mechanical properties of thin metallic films. The actuator is a beam undergoing large internal stresses built up during the deposition process. Al thin films are deposited partly on the actuator beam and on the substrate. By etching the structure, the actuator contracts and pulls the Al film. Full stress strain curves can be generated by designing a set of micromachines with various actuator lengths. In the present study, the displacements have been measured by scanning electronic microscopy. The stress is derived from simple continuum mechanics relationships. The tensile properties of Al films of various thicknesses have been tested. A marked increase of the strength with decreasing film thickness is observed.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Mining microarray data to predict the histological grade of a breast cancer

BACKGROUND: The aim of this study was to develop an original method to extract sets of relevant molecular biomarkers (gene sequences) that can be used for class prediction and can be included as prognostic and predictive tools. MATERIALS AND METHODS: The method is based on sequential patterns used as features for class prediction. We applied it to classify breast cancer tumors according to their histological grade. RESULTS: We obtained very good recall and precision for grades 1 and 3 tumors, but, like other authors, our results were less satisfactory for grade 2 tumors. CONCLUSIONS: We demonstrated the interest of sequential patterns for class prediction of microarrays and we now have the material to use them for prognostic and predictive applications

Prédiction du grade d'un cancer du sein par la découverte de motifs séquentiels contextuels dans des puces à ADN

National audienceLe cancer du sein reste de nos jours un problème de santé majeur et un véritable défi pour les biologistes et les professionnels de santé. Les puces à ADN permettent aujourd'hui d'étudier selon un jour nouveau les problématiques associées à cette maladie. Dans cet article, nous proposons de traiter les données issues des puces à ADN par le biais de l'extraction de motifs séquentiels contextuels (séquences de gènes ordonnés selon leur niveau d'expression associées à un contexte). L'objectif est de proposer une aide au diagnostic du grade d'une tumeur. Notre approche tient à la fois compte de l'information contenue dans les puces à ADN (exprimée par le biais de motifs séquentiels), mais également d'informations additionnelles d'ordre contextuel (e.g., âge du patient, taille de la tumeur, etc.) et qui sont associées aux données de puces à ADN lorsque celles-ci sont publiées en ligne. L'approche proposée a été évaluée sur des données réelles

Extraction de motifs spatio-temporels à différentes échelles avec gestion de relations spatiales qualitatives

ISBN : 978-163266234-7National audienceGeoreferenced databases contain a huge volume of temporal and spatial data. They are notably used in environmental analysis. Several works address the problem of mining those data, but none are able to take into account the richness of the data and especially their spatial and temporal dimensions. In this paper, we focus on the extraction of a new kind of spatiotemporal patterns which consider the relationship between spatial objects and also various geographical scales. We propose an algorithm, STR_PrefixGrowth, which can be applied on a huge amont of data. The proposed method is evaluated on hydrological data collected on the Saône basin during the last 19 years. Our experiments emphasize the contribution of our approach toward the existing methods.Les bases de données géoréférencées contiennent un important volume de données temporelles et spatiales. Elles sont par exemple particulièrement utilisées dans le cadre d'analyses environnementales. Plusieurs méthodes ont été proposées pour l'exploration de telles bases de données, mais aucune ne permet d'exploiter toute la richesse des données, en particulier leurs dimensions spatiales et temporelles. Dans cet article, nous introduisons un nouveau type de motifs spatio-temporels considérant les relations entre objets spatiaux mais aussi les différentes échelles géographiques. Nous proposons un algorithme d'extraction de motifs STR_PrefixGrowth applicable sur un important volume de données. Nous traitons un exemple de données hydrobiologiques collectées sur le bassin de la Saône durant les 19 dernières années. Les expérimentations menées soulignent l'intérêt de notre méthode par rapport aux méthodes existantes

Using smart people to build smarter: How smart cities attract and retain highly skilled workers to drive innovation (Belgium, Denmark, the Netherlands, Poland)

Smart cities have been heralded as new powerhouses of economic growth and their capacity to fill this promise strongly depends on how attractive they are to highly skilled people. In fact, talented professionals can be regarded as their precondition and the fuel of innovation. In this article, we try to articulate how outstanding smart cities have managed to consolidate and retain a highly skilled graduate workforce. To this end, we analyse recent institutional developments in the cities with smart ambitions that achieve the highest smartness scores and compare them to parallel developments in those that obtain the lowest scores or no score across four countries: Belgium, Denmark, the Netherlands and Poland. Taking from theories of economics of agglomeration and urban economics, and following a careful review of the relevant literature, we first highlight reasons that draw highly skilled workers to a smart city before identifying the cities which have proven most able to capitalise on them. In line with existing theories, this article finds that cities which enjoy greater administrative autonomy tend to successfully use this leeway to implement pro-growth policies and amplify them via a regulatory setting that itself encourages business development. Hence, our conclusion provides recommendations towards a pathway of reforms for smart cities willing to authorise more comprehensive policies in order to boost their attractiveness as locations of employment and reach their stated objectives

OrderGeneMiner : Logiciel pour l'extraction et la visualisation de motifs partiellement ordonnés à partir de puces à ADN

Démonstration du logiciel @ 13e Conférence Francophone sur l'Extraction et la Gestion des Connaissances (EGC 2013)Le Virus de l'Immunodéficience Humaine (VIH) est actuellement un problème majeur de santé publique. Depuis l'identification du VIH, plus de 20 millions de personnes ont été identifiées. Le VIH continue de ravager les populations dans le monde entier avec 3 millions de nouvelles infections par an. Contrairement au cancer, les approches de biologie intégrative sont toujours rares dans le domaine de la lutte contre le HIV. Dans cet article, nous proposons de contribuer au développement d'une telle stratégie, en présentant un logiciel de fouille de données qui va permettre d'appliquer les concepts de motifs séquentiels et de motifs partiellement ordonnés aux données de puces à ADN. Ce logiciel se focalise sur les besoins des biologistes: 1) permet à l'expert d'intéragir dans le processus d'extraction des motifs; 2) offre une visualisation des motifs extrait sous la forme d'un graphe coloré qui résume un ensemble de motifs séquentiels. Il en résulte une visualisation plus compacte et simple qui facilite l'interprétation des experts

Co2Vis: A Visual Analytics Tool for Mining Co-Expressed and Co-Regulated Genes Implied in HIV Infections

International audienceOne of the key challenges in human health is the identification of disease-causing genes like AIDS (Acquired ImmunoDeficiency Syndrome). Numerous studies have addressed this challenge through gene expression analysis. Due to the amount of data available, processing DNA microarrays in a way that makes biomedical sense is still a major issue.Statistical methods and data mining techniques play a key role in discovering previously unknown knowledge. However, applying such techniques in this context is difficult because the number of measurement points (i.e., gene expression levels) is much higher than the number of samples resulting in the well-known curse of dimensionality problem also called the high feature-to-sample ratio.We propose a combination of data mining and visual analytics methods to identify and render groups of genes implied in HIV infections and sharing common behaviors

HydroQual: Visual analysis of river water quality

International audienceEconomic development based on industrialization, intensive agriculture expansion and population growth places greater pressure on water resources through increased water abstraction and water quality degradation [40]. River pollution is now a visible issue, with emblematic ecological disasters following industrial accidents such as the pollution of the Rhine river in 1986 [31]. River water quality is a pivotal public health and environmental issue that has prompted governments to plan initiatives for preserving or restoring aquatic ecosystems and water resources [56]. Water managers require operational tools to help interpret the complex range of information available on river water quality functioning. Tools based on statistical approaches often fail to resolve some tasks due to the sparse nature of the data. Here we describe HydroQual, a tool to facilitate visual analysis of river water quality. This tool combines spatiotem-poral data mining and visualization techniques to perform tasks defined by water experts. We illustrate the approach with a case study that illustrates how the tool helps experts analyze water quality. We also perform a qualitative evaluation with these experts

Non-isothermal tensile tests during solidification of Al–Mg–Si–Cu alloys: Mechanical properties in relation to the phenomenon of hot tearing

An original set-up has been used to study the mechanical properties of aluminium alloys in tension during solidification with a high cooling rate (70 K/s). The mechanical behaviour of 6056 aluminium alloy with and without grain refiner has been investigated as well as that of mixtures between AA6056 and AA4047. The results show that the alloys exhibit a viscoplastic behaviour in the mushy state. A transition is observed between fracture in the mushy state and fracture in the solid state as a function of the displacement rate. This displacement rate at the transition depends on the cooling rate and on the composition of the alloy. The displacement before fracture is observed to be independent of displacement rate but to depend on the composition and on the solidification rate. Based on the observations a criterion for fracture in the mushy state is proposed. A simple rheological law describing the mechanical behaviour of the alloys is coupled to a finite element calculation giving the thermal field during the tensile test. This simulation is able to reproduce the mechanical response of the solidifying alloy during a non-isothermal test

Formation of hot tear under controlled solidification conditions

Aluminum alloy 7050 is known for its superior mechanical properties, and thus finds its application in aerospace industry. Vertical direct-chill (DC) casting process is typically employed for producing such an alloy. Despite its advantages, AA7050 is considered as a "hard-to-cast" alloy because of its propensity to cold cracking. This type of cracks occurs catastrophically and is difficult to predict. Previous research suggested that such a crack could be initiated by undeveloped hot tears (microscopic hot tear) formed during the DC casting process if they reach a certain critical size. However, validation of such a hypothesis has not been done yet. Therefore, a method to produce a hot tear with a controlled size is needed as part of the verification studies. In the current study, we demonstrate a method that has a potential to control the size of the created hot tear in a small-scale solidification process. We found that by changing two variables, cooling rate and displacement compensation rate, the size of the hot tear during solidification can be modified in a controlled way. An X-ray microtomography characterization technique is utilized to quantify the created hot tear. We suggest that feeding and strain rate during DC casting are more important compared with the exerted force on the sample for the formation of a hot tear. In addition, we show that there are four different domains of hot-tear development in the explored experimental window-compression, microscopic hot tear, macroscopic hot tear, and failure. The samples produced in the current study will be used for subsequent experiments that simulate cold-cracking conditions to confirm the earlier proposed model.This research was carried out within the Materials innovation institute (www.m2i.nl) research framework, project no. M42.5.09340