Pierre Auger

Bio: Pierre Auger is an academic researcher from University of Paris. The author has contributed to research in topics: Population & Fishing. The author has an hindex of 32, co-authored 158 publications receiving 3219 citations. Previous affiliations of Pierre Auger include Claude Bernard University Lyon 1 & Cheikh Anta Diop University.

Pattern and Waves for a Model in Population Dynamics with Nonlocal Consumption of Resources

Abstract: We study a reaction-diffusion equation with an integral term describing nonlocal consumption of resources in population dynamics. We show that a homogeneous equilibrium can lose its stability resulting in appearance of stationary spatial structures. They can be related to the emergence of biological species due to the intra-specific competition and random mutations. Various types of travelling waves are observed.

Atom probe and transmission electron microscopy study of aging of cast duplex stainless steels

Abstract: The microstructural evolution of Mo bearing and Mo free cast duplex stainless steels, induced by long term aging in the range 350–4507deg;C has been studied using atom probe and field ion microscopy and transmission electron microscopy. The salient features of this evolution at 350 and 400°C are spinodal decomposition and G phase precipitation in the ferrite. The nucleation of the G phase is enhanced by spinodal decomposition. Other intermetallic phases observed at higher temperatures may also be formed at 400°C. In the ferrite/ austenite interface, an intermetallic film, possibly an icosahedral phase, is formed after aging for 30 000 h at 400 and 450°C in Mo bearing steels, whereas interfacial M23C6 carbides precipitate in the Mo free materials. The observed evolution of the spatial and compositional parameters of the spinodal decomposition in Mo bearing steels is described and its relationship with the evolution of mechanical properties is outlined.MST/1185

Aggregation of Variables and Applications to Population Dynamics

Abstract: 1 IRD UR Geodes, Centre IRD de l’Ile de France, 32, Av. Henri Varagnat, 93143 Bondy cedex, France pierre.auger@bondy.ird.fr 2 Departamento de Matematicas, Universidad de Alcala, 28871 Alcala de Henares, Madrid, Spain rafael.bravo@uah.es 3 Laboratoire de Microbiologie, Geochimie et d’Ecologie Marines, UMR 6117, Centre d’Oceanologie de Marseille (OSU), Universite de la Mediterranee, Case 901, Campus de Luminy, 13288 Marseille Cedex 9, France Jean-Christophe.Poggiale@univmed.fr 4 Departamento de Matematicas, E.T.S.I. Industriales, U.P.M., c/ Jose Gutierrez Abascal, 2, 28006 Madrid, Spain esanchez@etsii.upm.es 5 IXXI, ENS Lyon, 46 allee d’Italie, 69364 Lyon cedex 07, France tri.nguyen-huu@ens-lyon.fr

Complex ecological models with simple dynamics: From individuals to populations

Abstract: The aim of this work is to study complex ecological models exhibiting simple dynamics We consider large scale systems which can be decomposed into weakly coupled subsystems Perturbation Theory is used in order to get a reduced set of differential equations governing slow time varying global variables As examples, we study the influence of the individual behaviour of animals in competition and predator-prey models The animals are assumed to do many activities all day long such as searching for food of different types The degree of competition as well as the predation pressure are dependent upon these activities Preys are more vulnerable when doing some activities during which they are very exposed to predators attacks rather than for others during which they are hidden We study the effect of a change in the average individual behaviour of the animals on interspecific relationships Computer simulations of the whole sets of equations are compared to simulations of the reduced sets of equations

Evolution and the Theory of Games

Abstract: In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

Dynamic Energy and Mass Budgets in Biological Systems

Abstract: The Dynamic Energy Budget theory unifies the commonalties between organisms, as prescribed by the implications of energetics, and links different levels of biological organisation (cells, organisms and populations). The theory presents simple mechanistic rules that describe the uptake and use of energy and nutrients and the consequences for physiological organization throughout an organism's life cycle. All living organisms are covered in a single quantitative framework, the predictions of which are tested against a variety of experimental results at a range of levels of organisation. The theory explains many general observations, such as the body size scaling relationships of certain physiological traits, and provides a theoretical underpinning to the method of indirect calorimetry. In each case, the theory is developed in elementary mathematical terms, but a more detailed discussion of the methodological aspects of mathematical modelling is also included.