De la nécessité de l'intégration d'un modèle d'hippocampe dans une approche corticale de la sélection de l'action

Colloque avec actes et comité de lecture.Cet article présente dans un premier temps une architecture inspirée par les données neurobiologiques concernant le cortex permettant à un agent autonome d'évoluer dans un environnement ouvert (démuni d'obstacles). Cet animat est alors capable d'agir en accord avec l'état de ses différentes motivations. Cependant, cette mémoire associative procédurale (le savoir comment) ne semble pas suffisante à la survie de l'animat. Il semble donc qu'il faille adjoindre à cette architecture l'équivalent d'une mémoire explicite (le savoir quoi) afin de fournir à l'animat la possibilité de manipuler des représentations à caractère global et épisodique pour l'élaboration d'un comportement. l'introduction d'un modèle d'hippocampe semble constituer une solution adéquate

Neuronal mechanisms for sequence learning in behavioral modeling

Colloque avec actes et comité de lecture.Sequence learning and management have been reported as central features in behavioral studies. Indeed, tasks like route memorization or planning are temporal behaviors and can be hardly modeled without taking the temporal aspect into consideration. On the contrary, classical information processing tools are not very efficient at such temporal processing. In this paper, we shortly review these tools and show that another approach, close to neurobiological modeling, can yield a variety of neuronal mechanisms for several aspects of sequence learning and management

Integration of Biologically Inspired Temporal Mechanisms into a Cortical Framework for Sequence Processing

Contribution à un ouvrage.Whereas classical connectionist models can hardly cope with difficult dynamic tasks with a strong temporal factor, many temporal mechanisms inspired with neurobiological data has been proposed in the past and yield efficient time processing properties. The goal of this chapter is to show that, beyond these isolated mechanisms, their integration in a more general architectural and functional framework can potentiate their power and make them usable for non trivial behavioral tasks. We propose a cerebral framework, from the neuronal to the behavioral level, and give some applicative illustrations that underline the encouraging results obtained today

Functional Foods and Nutraceuticals in a Market of Bolivian Immigrants in Buenos Aires (Argentina)

This paper presents the results of a research in urban ethnobotany, conducted in a market of Bolivian immigrants in the neighborhood of Liniers, Ciudad Autónoma de Buenos Aires (Argentina). Functional foods and nutraceuticals belonging to 50 species of 18 families, its products, and uses were recorded. Some products are exclusive from the Bolivian community; others are frequent within the community, but they are also available in the general commercial circuit; they are introduced into it, generally, through shops called dietéticas (“health-food stores”), where products associated with the maintenance of health are sold. On this basis, the traditional and nontraditional components of the urban botanical knowledge were evaluated as well as its dynamics in relation to the diffusion of the products. Both the framework and methodological design are innovative for the studies of the urban botanical knowledge and the traditional markets in metropolitan areas

An Asymptotic Preserving Scheme for the Euler equations in a strong magnetic field

This paper is concerned with the numerical approximation of the isothermal Euler equations for charged particles subject to the Lorentz force. When the magnetic field is large, the so-called drift-fluid approximation is obtained. In this limit, the parallel motion relative to the magnetic field direction splits from perpendicular motion and is given implicitly by the constraint of zero total force along the magnetic field lines. In this paper, we provide a well-posed elliptic equation for the parallel velocity which in turn allows us to construct an Asymptotic-Preserving (AP) scheme for the Euler-Lorentz system. This scheme gives rise to both a consistent approximation of the Euler-Lorentz model when epsilon is finite and a consistent approximation of the drift limit when epsilon tends to 0. Above all, it does not require any constraint on the space and time steps related to the small value of epsilon. Numerical results are presented, which confirm the AP character of the scheme and its Asymptotic Stability

Numerical approximation of the Euler-Maxwell model in the quasineutral limit

International audienceWe derive and analyze an Asymptotic-Preserving scheme for the Euler-Maxwell system in the quasi-neutral limit. We prove that the linear stability condition on the time-step is independent of the scaled Debye length $\lambda$ when $\lambda \to 0$. Numerical validation performed on Riemann initial data and for a model Plasma Opening Switch device show that the AP-scheme is convergent to the Euler-Maxwell solution when $\Delta x/ \lambda \to 0$ where $\Delta x$ is the spatial discretization. But, when $\lambda /\Delta x \to 0$, the AP-scheme is consistent with the quasi-neutral Euler-Maxwell system. The scheme is also perfectly consistent with the Gauss equation. The possibility of using large time and space steps leads to several orders of magnitude reductions in computer time and storage

Uncertainty quantification for kinetic models in socio-economic and life sciences

Kinetic equations play a major rule in modeling large systems of interacting particles. Recently the legacy of classical kinetic theory found novel applications in socio-economic and life sciences, where processes characterized by large groups of agents exhibit spontaneous emergence of social structures. Well-known examples are the formation of clusters in opinion dynamics, the appearance of inequalities in wealth distributions, flocking and milling behaviors in swarming models, synchronization phenomena in biological systems and lane formation in pedestrian traffic. The construction of kinetic models describing the above processes, however, has to face the difficulty of the lack of fundamental principles since physical forces are replaced by empirical social forces. These empirical forces are typically constructed with the aim to reproduce qualitatively the observed system behaviors, like the emergence of social structures, and are at best known in terms of statistical information of the modeling parameters. For this reason the presence of random inputs characterizing the parameters uncertainty should be considered as an essential feature in the modeling process. In this survey we introduce several examples of such kinetic models, that are mathematically described by nonlinear Vlasov and Fokker--Planck equations, and present different numerical approaches for uncertainty quantification which preserve the main features of the kinetic solution.Comment: To appear in "Uncertainty Quantification for Hyperbolic and Kinetic Equations

Huertos familiares periurbanos de las costas de Ensenada-Berisso y de la Isla Martín García (Buenos Aires, Argentina)

Este trabajo presenta los resultados de un estudio de la situación actual de 16 huertos familiares periurbanos de las costas de Ensenada-Berisso y de la Isla Martín García (Buenos Aires, Argentina), en relación a su contexto histórico de transformaciones ecológicas, culturales y económicas, donde se evidencia el carácter adaptativo de las prácticas hortícolas, los saberes tradicionales que las sustentan y su aporte a la agrobiodiversidad local. Se relevó la composición florística de los huertos, y se aplicaron métodos cualitativos para el relevamiento de datos etnobotánicos. Se registraron 80 taxones cultivados y productos obtenidos a partir de estos, para consumo familiar y comercialización a pequeña escala, como suplemento para la economía doméstic

Adaptógenos: plantas medicinales tradicionales comercializadas como suplementos dietéticos en la conurbación Buenos Aires-La Plata (Argentina)

En el presente trabajo se presentan los resultados de un estudio sobre tres especies de las cuales se comercializan productos considerados adaptógenos: Lepidium meyenii Walp. (Brassicaceae), "maca", Morinda citrifolia L. (Rubiaceae), "noni", y Petiveria alliacea L. (Phytolaccaceae), "pipi". Los datos provienen de estudios en Etnobotánica urbana realizados en la conurbación Buenos Aires-La Plata, se presentan los usos tradicionales de las especies, sus vías de ingreso, comercialización y difusión como suplementos dietéticos en el contexto pluricultural urbano, los modos actuales de empleo y los saberes relacionados, que forman parte del conocimiento botánico local. De este modo, se evalúan las modificaciones en los usos originalmente asignados, como consecuencia de la expansión de los productos en el marco de la globalización, y los cambios consecuentes en los patrones tradicionales de saberes, creencias y prácticas referidos a estos recursos vegetale

A Multilevel Monte Carlo Asymptotic-Preserving Particle Method for Kinetic Equations in the Diffusion Limit

We propose a multilevel Monte Carlo method for a particle-based asymptotic-preserving scheme for kinetic equations. Kinetic equations model transport and collision of particles in a position-velocity phase-space. With a diffusive scaling, the kinetic equation converges to an advection-diffusion equation in the limit of zero mean free path. Classical particle-based techniques suffer from a strict time-step restriction to maintain stability in this limit. Asymptotic-preserving schemes provide a solution to this time step restriction, but introduce a first-order error in the time step size. We demonstrate how the multilevel Monte Carlo method can be used as a bias reduction technique to perform accurate simulations in the diffusive regime, while leveraging the reduced simulation cost given by the asymptotic-preserving scheme. We describe how to achieve the necessary correlation between simulation paths at different levels and demonstrate the potential of the approach via numerical experiments.Comment: 20 pages, 7 figures, published in Monte Carlo and Quasi-Monte Carlo Methods 2018, correction of minor typographical error