Frequency Locking in Countable Cellular Systems, Localization of (Asymptotic) Quasi-Periodic Solutions of Autonomous Differential Systems.

International audienceWe address the question of frequency locking in coupled differential systems and of the existence of some quasi-periodic solutions of a certain kind of differential systems. Those systems are named "cellular systems" quite generally as they deal with countable numbers of coupled systems in some general Banach spaces. Moreover, the inner dynamics of each subsystem does not have to be specified. We reach some general results about how the frequency locking phenomenon is related to the structure of the coupling map. Those results can be restated in terms of localization of a certain type of quasi-periodic solution of differential systems that may be seen as cellular systems. This paper gives some explanations about how and why synchronized behaviors naturally occur in a wide variety of complex systems

SYNCHRONIZATION OF ASYMPTOTICALLY PERIODIC BEHAVIORS IN COUNTABLE CELLULAR SYSTEMS

International audienceWe address the question of frequencies locking in coupled differential systems and of the existence of (component) quasi-periodic solutions of some kind of differential systems. These systems named cellular systems are quite general as they deal with countable number of coupled systems in some general Banach spaces. Moreover, the inner dynamics of each subsystem does not have to be specified. We reach some general results about how the frequencies locking phenomenon is related to the structure of the coupling map, and therefore about the localization of a certain type of quasi-periodic solutions of differential systems that may be seen as cellular systems. This paper gives some explanations about how and why synchronized behaviors naturally occur in a wide variety of complex systems

Tissular coupling and frequency locking I finite population

International audienceSynchronization is an extremely important and interesting emergent property of complex systems. The first example found in literature goes back to the 17th century with Christiaan Huygens works. This kind of emergent behavior can be found in artificial systems as well as in natural ones and at many scales (from cell to whole ecological systems). Biology abounds of peri- odic and synchronized phenomena and the works of Ilya Prigogine showed that such behaviors arise within specific conditions: a dissipative structure gener- ally associated to a non-linear dynamic. Biological systems are open, they evolve far from thermodynamic equilibrium and are subject to numerous reg- ulating processes, leading to highly non-linear dynamics. Therefore periodic behaviors appear (with or without synchronization) at any scale. More generally, life itself is governed by circadian rhythms. Those phenomena are as much attractive as they are often spectacular: from cicada populations that appear spontaneously every ten or thirteen years or networks of heart cells that beat together to huge swarms in which fireflies, gathered in a same tree, flash simultaneously. Furthermore, beyond biology one can find a wide source of examples in completely different fields of science (e.g. in behav- ioral psychology with the example of synchronizing applause). For much more artificial and/or theoretical examples, one can consider the whole field of research that studies the coupling of smooth dynamical systems. Nowa- days, it is one of the most important subject related to non-linear systems' dynamics, especially through the notion of chaotic systems' synchronization. This wide source of examples leads the field of research to be highly interdisciplinary, from pure theory to concrete applications and experimen- tations. The classical concept of synchronization is related to the locking of the basic frequencies and instantaneous phases of regular oscillations. Those questions are usually addressed by studying specific kinds of coupled discrete or differential systems, using classical tools of the field. Convinced that synchronization phenomenon is completely natural in a large variety of coupled dynamical systems, we propose a new approach of the subject: firstly, we ask the question of synchronization differently than the usual way. Rather than trying to prove that synchronization actually takes place, we search conditions under which frequencies are locked as soon as the whole system oscillate. Secondly we enlarge the scope of handled models, by building a general framework for coupled systems called " tissular coupling ". This framework is inspired by biological observations at cell's scale, but relevant at any scale of modeling. Under some general assumptions on the kind of interactions that constitute the coupling of the systems, we prove that for a wide class of tissular coupling systems, frequencies are mutually locked to a single value as soon as the whole population is oscillating. This paper exhibits our model of tissular coupling and the frequency locking in the case of a finite number of coupled systems. In the first section we present some mathematical tools and the background we have used in order to study synchronization issue (the results exposed at the end of this paper is only a part of what we have fulfilled, and surely a really small part of what can be done using tissular coupling, this is why we state this framework in its general form). Then, we describe dynamical objects on which we focus, namely the tissular coupling and periodical motions of a population. In the second section we expose a useful way to reduce the problem to a structural one, with no more reference to the dynamics of the coupled systems. In the final section we exhibit some natural conditions under which we are able to prove the main result of this paper, a case of synchronization, in terms of frequencies locking. In a second paper [3] we expose the case of an infinite compact and connected population, which is processed with different mathematical tools

Frequency Locking in Tissular Coupling

International audienceWe expose a framework, inspired by biological observations, dedicated to modeling complex living systems as coupled systems. In particular, we use this framework to adress a main question in the field of living systems: the synchronization phenomenon. This kind of model, named tissular coupling, is quite general and, using different methods from those usually used in this field of research, we reach global results relative to the frequencies locking problem in both finite and continuous populations

CHAMELEON: A Learning Virtual Bot For Believable Behaviors In Video Game

International audienceThe believability of a virtual world can be increased by improving the behavior of the characters in it. Consid- ering literature, we choose a model developed by Le Hy to generate the behaviors by imitation. The model uses probability distributions to find which decision to choose depending on the sensors. Then actions are chosen de- pending on the sensors and the decision. The core idea of the model is promising but we propose to enhance the expressiveness of the model and the associated learning algorithm. We hope the model will be able to generate more believable behaviors and learn them with minimal a priori knowledge. We first revamp the organization of the sensors and motors by semantic refinement and add a focus mechanism in order to improve the believabil- ity. To achieve believability, we integrate an algorithm to learn the topology of the environment. Then, we re- vamp the learning algorithm to be able to learn much more parameters and with greater precision at the cost of its time of convergence

PLGA-Based Nanoparticles for Neuroprotective Drug Delivery in Neurodegenerative Diseases

Treatment of neurodegenerative diseases has become one of the most challenging topics of the last decades due to their prevalence and increasing societal cost. The crucial point of the non-invasive therapeutic strategy for neurological disorder treatment relies on the drugs’ passage through the blood-brain barrier (BBB). Indeed, this biological barrier is involved in cerebral vascular homeostasis by its tight junctions, for example. One way to overcome this limit and deliver neuroprotective substances in the brain relies on nanotechnology-based approaches. Poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) are biocompatible, non-toxic, and provide many benefits, including improved drug solubility, protection against enzymatic digestion, increased targeting efficiency, and enhanced cellular internalization. This review will present an overview of the latest findings and advances in the PLGA NP-based approach for neuroprotective drug delivery in the case of neurodegenerative disease treatment (i.e., Alzheimer’s, Parkinson’s, Huntington’s diseases, Amyotrophic Lateral, and Multiple Sclerosis)

Probabilistic and mean-field model of COVID-19 epidemics with user mobility and contact tracing

23 pages, 5 figuresWe propose a detailed discrete-time model of COVID-19 epidemics coming in two flavours, mean-field and probabilistic. The main contribution lies in several extensions of the basic model that capture i) user mobility - distinguishing routing, i.e. change of residence, from commuting, i.e. daily mobility - and ii) contact tracing procedures. We confront this model to public data on daily hospitalizations, and discuss its application as well as underlying estimation procedures

3D individual based model for simultaneous growth and interaction of L. Monocytogenes and lactic acid bacteria

International audienceBy interacting with pathogens, lactic acid bacteria (LAB) are able to contribute to food safety. By means of their lactic acid production which induces pH decrease, LAB influence the growth of pathogens. The aim of this study is to model and simulate lactic acid production, pH evolution, according to carbohydrate concentration in media, temperature, water activity and ratio of both population

ECR Ion sources for radioactive ion beam production

17th workshop on ECR Ion Sources and their Applications, Lanzhou, Chine (2006)International audienceECRIS's dedicated to radioactive ion producton must be as efficient as those used for production of stable elements, but in addition they are subject to more specific constraints such as radiation hardness, short atom-to-ion transformation time, beam purity and low cost. Up to now, different target/ion-source system (TISSs) have been designed, using singly-charged ECRISs, multi-charged ion sources or an association of singly-to-multi-charged ECRISs. The main goal, constraints and advantages of different existing ECR setups wil be compared before a more detailed description is given of the one designed for the SPIRAL II project and ist future improvements

Production of multi-charged phosphorus ions with ecris 'SUPERSHyPIE' at GANIL

The Ganil's Ion Production Group tested the source SUPERSHyPIE123 for theproduction of phosphorus n+ ion beams. The SUPERSHyPIE ecris is used for many testsof multi-charged ion production and supply ion beams for LIMBE4 (low energie beamline). This ion source works with a 14.5ghz RF power injected by a circular waveguide inthe axis of the sourc