Language-trained animals: a window to the "black box"

Animals have to process quantity of information in order to take decisions and adapt their behaviors to their physical and social environment. They have to remember previous events (learning), to cope with their internal (motivational and emotional) states and to display flexible behavioral responses. From a human point of view it is quite impossible to access all those information, not only because of the sensorial channels used that can vary but also because all the processing phase occurs in the “black box” and non-human animals are not able to express verbally what they think, feel or want. Though useful information might lie in the “collected data” (animal mind), extracting them into insightful knowledge with human-accessible form (clear meaning, no interpretation) presents a demanding and sophisticated undertaking. Several scientists decided to trained different individuals from several species (apes, dolphins, grey parrots, dogs) in order to teach them a new communicative system that they could share with us. Here, the different studies (techniques and species used) are presented, their constrains but also the main findings

Uniform estimates for transmission problems with high contrast in heat conduction and electromagnetism

In this paper we prove uniform a priori estimates for transmission problems with constant coefficients on two subdomains, with a special emphasis for the case when the ratio between these coefficients is large. In the most part of the work, the interface between the two subdomains is supposed to be Lipschitz. We first study a scalar transmission problem which is handled through a converging asymptotic series. Then we derive uniform a priori estimates for Maxwell transmission problem set on a domain made up of a dielectric and a highly conducting material. The technique is based on an appropriate decomposition of the electric field, whose gradient part is estimated thanks to the first part. As an application, we develop an argument for the convergence of an asymptotic expansion as the conductivity tends to infinity

L’analyse démographique et la famille : prémisses d’une autocritique

Dans cet article, l’auteur montre que ce qui caractérise la démographie de la famille, c’est que l’unité statistique y est la famille, et non l’individu, comme en démographie générale. Par ailleurs, les démographes se sont jusqu’ici intéressés davantage à la famille « biologique » qu’à la famille « statistique », ce qui suppose une adaptation des méthodes traditionnelles d’analyse. Les événements démographiques familiaux qui modifient le nombre de familles statistiques font habituellement l’objet d’un enregistrement qui permet l’analyse. Dans une perspective longitudinale, l’auteur découpe l’histoire de la famille en séquences successives qu’on peut appeler le calendrier démographique de la famille. Cependant, les variables permettant l’étude de ce calendrier ne font pas l’objet d’un enregistrement approprié, particulièrement les intervalles et les durées. En dépit de son intérêt évident, la démographie de la famille est peu développée. Les défaillances de l’observation de certains événements (séparations, migrations, départs des enfants) ont grandement nui à l’émergence d’une démographie de la famille. De plus, la démographie s’est intéressée jusqu’ici à l’étude des phénomènes contribuant directement au renouvellement quantitatif de l’ensemble de la population, délaissant l’analyse sur une base familiale. L’essor d’une véritable démographie de la famille nécessitera la généralisation et la systématisation de l’utilisation du couple et de la famille comme unités d’observation et d’analyse

Wentzel--Kramers--Brillouin Expansions and Generalized Impedance Transmission Conditions for Thin-Layer Problems in Electromagnetism with Application to Biological Cells

In this work we derive a WKB expansion for the electromagnetic fields solution of the time-harmonic Maxwell equations set in a domain with a thin layer. As a by-product of this expansion we obtain new second order asymptotic models with generalized impedance transmission conditions that turn out to depend on the mean curvature of the boundary of the subdomain surrounded by the thin layer. We show that these models can be easily integrated in finite element methods by developing mixed variational formulations. One application of this work concerns the computation of the electromagnetic field in biological cells

Modified home range kernel density estimators that take environmental interactions into account

International audienceBackground: Kernel density estimation (KDE) is a major tool in the movement ecologist toolbox that is used to delineate where geo-tracked animals spend their time. Because KDE bandwidth optimizers are sensitive to temporal autocorrelation, statistically-robust alternatives have been advocated, first, data-thinning procedures, and more recently, autocorrelated kernel density estimation (AKDE). These yield asymptotically consistent, but very smoothed distributions, which may feature biologically unrealistic aspects such as spilling beyond impassable borders.Method: I introduce a semi-parametric variant of AKDE designed to extrapolate more realistic home range shapes by incorporating movement mechanisms into the bandwidth optimizer and into the base kernels. I implement a first approximative version based on the step selection framework. This method allows accommodating land cover selection, permeability of linear features, and attraction for select landscape features when delineating home ranges.Results: In a plains zebra (Equus quagga), the reluctance to cross a railway, the avoidance of dense woodland, and the preference for grassland when foraging created significant differences between the estimated home range contours by the new and by previous methods.Conclusion: There is a tradeoff to find between fully parametric density estimators, which can be very realistic but need to be provided with a good model and adequate environmental data, and non-parametric density estimators, which are more widely applicable and asymptotically consistent, but whose details are bandwidth-limited. The proposed semi-parametric approach attempts to strike this balance, but I outline a few areas of future improvement. I expect the approach to find its use in studies that compare extrapolated resource availability and interpolated resource use, in order to discover the movement mechanisms that we need to improve the extrapolations