Adaptation Knowledge Discovery from a Case Base

In case-based reasoning, the adaptation step depends in general on domain-dependent knowledge, which motivates studies on adaptation knowledge acquisition (AKA). CABAMAKA is an AKA system based on principles of knowledge discovery from databases. This system explores the variations within the case base to elicit adaptation knowledge. It has been successfully tested in an application of case-based decision support to breast cancer treatment

Case Base Mining for Adaptation Knowledge Acquisition

In case-based reasoning, the adaptation of a source case in order to solve the target problem is at the same time crucial and difficult to implement. The reason for this difficulty is that, in general, adaptation strongly depends on domain-dependent knowledge. This fact motivates research on adaptation knowledge acquisition (AKA). This paper presents an approach to AKA based on the principles and techniques of knowledge discovery from databases and data-mining. It is implemented in CABAMAKA, a system that explores the variations within the case base to elicit adaptation knowledge. This system has been successfully tested in an application of case-based reasoning to decision support in the domain of breast cancer treatment

Exploitation du monde animal sur le versant nord des Pyrénées au Tardiglaciaire

International audienceLes changements climatiques survenus entre la fin du Tardiglaciaire et le début du Postglaciaire ont modifié de manière considérable l'environnement dans lequel vivaient les populations préhistoriques. Dans le Sud de la France, les grandes étendues steppiques dans lesquelles évoluaient de larges troupeaux d'Ongulés sont peu à peu remplacées par des forêts. Ces écosystèmes cloisonnés abritent une biomasse de grands Herbivores plus faible que les grandes plaines. Par ailleurs, l'augmentation des températures s'accompagne d'un accroissement de la saison végétative des plantes qui, dès lors, sont susceptibles d'être plus intensément exploitées par les groupes humains. Ainsi, du point de vue des ressources alimentaires, le réchauffement postglaciaire aurait eu pour conséquence un élargissement de la diète au profit des petites espèces animales et des végétaux. Pourtant, dans le Nord et l'Est de la France, les travaux de A. Bridault (1993; 1997) ont montré que, pour les grands mammifères, les spectres fauniques n'étaient pas plus diversifiés au Mésolithique qu'au Magdalénien. Ses résultats sur la petite faune réfutent également l'hypothèse d'un élargissement systématique de la diète au profit des petites espèces animales à partir du Mésolithique. De telles études montrent la nécessité de tester, dans le sud de la France, la validité de cette hypothèse. Par une analyse critique des données taphonomiques et archéozoologiques disponibles, nous essaierons de voir si, sur le versant nord des Pyrénées, le réchauffement est, effectivement, à l'origine de l'apparition de nouvelles stratégies alimentaires fondées sur une diversification des ressources, stratégies nouvelles en rupture avec les économies de chasse paléolithiques dépendantes du grand gibier )Les changements climatiques survenus entre la fin du Tardiglaciaire et le début du Postglaciaire ont modifié de manière considérable l'environnement dans lequel vivaient les populations préhistoriques. Dans le Sud de la France, les grandes étendues steppiques dans lesquelles évoluaient de larges troupeaux d'Ongulés sont peu à peu remplacées par des forêts. Ces écosystèmes cloisonnés abritent une biomasse de grands Herbivores plus faible que les grandes plaines. Par ailleurs, l'augmentation des températures s'accompagne d'un accroissement de la saison végétative des plantes qui, dès lors, sont susceptibles d'être plus intensément exploitées par les groupes humains. Ainsi, du point de vue des ressources alimentaires, le réchauffement postglaciaire aurait eu pour conséquence un élargissement de la diète au profit des petites espèces animales et des végétaux. Pourtant, dans le Nord et l'Est de la France, les travaux de A. Bridault (1993; 1997) ont montré que, pour les grands mammifères, les spectres fauniques n'étaient pas plus diversifiés au Mésolithique qu'au Magdalénien. Ses résultats sur la petite faune réfutent également l'hypothèse d'un élargissement systématique de la diète au profit des petites espèces animales à partir du Mésolithique. De telles études montrent la nécessité de tester, dans le sud de la France, la validité de cette hypothèse. Par une analyse critique des données taphonomiques et archéozoologiques disponibles, nous essaierons de voir si, sur le versant nord des Pyrénées, le réchauffement est, effectivement, à l'origine de l'apparition de nouvelles stratégies alimentaires fondées sur une diversification des ressources, stratégies nouvelles en rupture avec les économies de chasse paléolithiques dépendantes du grand gibier (Barbaza, 1999). Bibliographie Barbaza M. (1999) Les civilisations postglaciaires - La vie dans la grande forêt tempérée. Histoire de la France préhistorique. Maison des Roches, Paris, 126 p. Bridault A. (1993) Les économies de chasse épipaléolithiques et mésolithiques dans le nord de la France, Thèse de doctorat, Université Paris X, 552. Bridault A. (1997) Chasseurs, ressources animales et milieux dans le nord de la France de la fin du Paléolithique à la fin du Mésolithique : problématique et état de la recherche. In Le Tardiglaciaire en Europe du Nord-Ouest, J.-P. Fagnart et A. Thévenin (ed.), pp. 165-176. Paris : CTHS

Catalysis of the electrochemical reduction of oxygen by bacteria isolated from electro-active biofilms formed in seawater

Biofilmsformed in aerobic seawater on stainless steel are known to be efficient catalysts of the electrochemicalreduction of oxygen. Based on their genomic analysis, seven bacterial isolates were selected and a cyclic voltammetry (CV) procedure was implemented to check their electrocatalytic activity towards oxygenreduction. All isolates exhibited close catalytic characteristics. Comparison between CVs recorded with glassy carbon and pyrolytic graphite electrodes showed that the catalytic effect was not correlated with the surface area covered by the cells. The low catalytic effect obtained with filtered isolates indicated the involvement of released redox compounds, which was confirmed by CVs performed with adsorbed iron–porphyrin. None of the isolates were able to form electro-activebiofilms under constant polarization. The capacity to catalyze oxygenreduction is shown to be a widespread property among bacteria, but the property detected by CV does not necessarily confer the ability to achieve stable oxygenreduction under constant polarization

THE USE OF GLOBAL SENSITIVITY ANALYSIS FOR ASSESSING CAPABILITY OF THE MTG/FCI INSTRUMENT TO DETECT AEROSOLS

International audienceThe Flexible Combined Imager (FCI) is an instrument to be borne by the future geostationary meteorological satellite Meteosat Third Generation (MTG). A numerical simulator was set up to provide simulated outputs of the instrument. It includes top-of-atmosphere scene of upwelling spectral radiance obtained by a radiative transfer model in the clear atmosphere, and the transfer function of the FCI. The sensitivity of the sensor outputs to aerosol properties is studied by varying the inputs defining the scenes and their illumination. The Global Sensitivity Analysis (GSA) with the Sobol' decomposition is applied to the outputs of the simulator, yielding a ranking of the inputs with respect to their influence on the FCI numerical outputs. The results are presented for all visible and near infrared channels of the FCI for desert type of aerosols according to the OPAC database. The study highlights the most relevant channels for aerosol detection and characterization and gives assessment of the different sources of uncertainties in aerosol retrieval with such channels

Heterogeneous individual motility biases group composition in a model of aggregating cells

Aggregative life cycles are characterized by alternating phases of unicellular growth and multicellular development. Their multiple, independent evolutionary emergence suggests that they may have coopted pervasive properties of single-celled ancestors. Primitive multicellular aggregates, where coordination mechanisms were less efficient than in extant aggregative microbes, must have faced high levels of conflict between different co-aggregating populations. Such conflicts within a multicellular body manifest in the differential reproductive output of cells of different types. Here, we study how heterogeneity in cell motility affects the aggregation process and creates a mismatch between the composition of the population and that of self-organized groups of active adhesive particles. We model cells as self-propelled particles and describe aggregation in a plane starting from a dispersed configuration. Inspired by the life cycle of aggregative model organisms such as Dictyostelium discoideum or Myxococcus xanthus, whose cells interact for a fixed duration before the onset of chimeric multicellular development, we study finite-time configurations for identical particles and in binary mixes. We show that co-aggregation results in three different types of frequency-dependent biases, one of which is associated to evolutionarily stable coexistence of particles with different motility. We propose a heuristic explanation of such observations, based on the competition between delayed aggregation of slower particles and detachment of faster particles. Unexpectedly, despite the complexity and non-linearity of the system, biases can be largely predicted from the behavior of the two corresponding homogenous populations. This model points to differential motility as a possibly important factor in driving the evolutionary emergence of facultatively multicellular life-cycles

OSIrIS: a physically based simulation tool to improve training in thermal infrared remote sensing over urban areas at high spatial resolution

International audienceThis paper describes an infrared image simulator for remote sensing applications, called OSIrIS (outdoor scene and infrared image simulation). It has been developed partly for training and reproduces with great details the physical phenomena that play a major role in complex urban environment. OSIrIS performs a synthesis of scene based on a 3-D description of the landscape with a high spatial resolution (0.5 – 10 m). The physical processes are briefly described and their importance with respect to the objectives are discussed. Thermal emission depends on temperature and generally dominates the signal. Temperature is governed by heat equation and is solved by the means of boundary conditions such as in-depth temperature and flux balance at surface. Main parameters are solar and atmospheric radiations, wind, heat conduction and changes in humidity. An innovative approach was developed to take into account variations in time of the interactions between the landscape and the physical processes. OSIrIS aims at simulating situations that are encountered in reality. It enables users self-formation, helping them understanding changes in image radiance as a function of the input parameters and their own simulation requirements. Examples are given that illustrate specific aspects of infrared images

Numerical Approach Dedicated to Nozzle Tip Clearance Flow Analysis in Variable Geometry Radial Turbines

The present paper consists in a numerical analysis of a variable geometry radial turbine stage, for three opening configurations. The presence of the endwall clearance in the stator creates additional secondary flows upstream from the rotor, which tend to increase the stator–rotor interactions. Those interactions are filtered in steady-state simulations, for which the accuracy is expected to decrease. A comparison between steady-state mixing plane simulations and a Non Linear Harmonic (NLH) approach is thus proposed, together with an analysis of the influence of the numbers of harmonics chosen for the NLH simulations. The results show that the implementation of clearances in the simulations increases the discrepancies between the two methods, especially for configurations naturally sensitive to stator–rotor interactions (open stator configuration). Regarding the number of harmonics for the numerical setting, a criterion proposed in the literature is discussed at the end of the paper, and provides good guidelines in order to avoid a full harmonics convergence analysis