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Analyse TOpologique et MOdélisation de SYstèmes Dynamiques

ATOMOSYD is an acronym to designate the approach we develop to investigate dynamical systems. We are concerned by the topological analysis, that is, a global approach of the phase portrait, and global modelling which corresponds to the possibility to obtain a set of differential equations from measurements.

This web site is devoted to any features related to the nonlinear dynamical systems theory. Of course, our research activities can be found in section A research group but other topics are also considered as

- Dynamical systems

- Algorithms for investigating data

- Data sets useful for applying new tools

We are working for leaving this web site alive. If you have any remark, please, tell us

News

In this period where irrationality is dominant, I provide you here a link to an open letter (in French) by a French nephrologist, Pr Gilles Deray, from the hospital La Pitié-Salpétrière :

Coronavirus, beware of danger, but not the one you think.

For 30 years, from my hospital observatory, I have experienced many health crises, HIV, SARS, MERS, resurgence of tuberculosis, multi-resistant bacteria. We managed them calmly and very effectively.
None induced the current panic.
I have never experienced such concern for an infectious disease and for any other disease.
And yet, I am not worried about the medical consequences of Coronavirus. Nothing in the current figures on mortality and the spread of the virus justifies the global health panic and, especially, the economic panic.
The measures taken are appropriate and effective and will allow the epidemic to be controlled. This is already the case in China, the initial and by far the most important source of this infectious agent, where the epidemic is dying out. The near future will tell if I was wrong.

On the other hand,
- I am concerned about the theft of masks and that of those necessary for the protection of caregivers and people at risk, our elders and those already sick, in particular immunocompromised patients, are distributed for zero efficiency in airports, cafes and shopping centers.
- I am worried about theft of cleaning gels.
- I am worried about these brawls to buy toilet paper and boxes of rice and pasta.
- I am worried about this terror which leads to making obscene stocks of food in countries where it is available in an equally obscene abundance.
- I am worried about our elders who are already alone and that we should no longer see or touch for fear of killing them. They will die faster but "only" from loneliness. We used not to visit our parents and grandparents if we had the flu, not to avoid them "just in case" and for an indefinite period, it is nothing different for the coronavirus.
- I am worried that health will become an object of warlike communication and conflict like any other, when it should be an ultimate cause of struggle in the rally.
- I am worried about our elders who are already alone and that we should no longer see or touch for fear of killing them. They will die faster but "only" from loneliness. We used not to visit our parents and grandparents if we had the flu, not to avoid them "just in case" and for an indefinite period, it is nothing different for the coronavirus
- I am worried that health will become an object of warlike communication and conflict like any other, when it should be an ultimate cause of struggle in the rally.
- I am worried that our health system, already in great difficulty, will soon be overwhelmed by an influx of patients at the slightest sign of influenza-like illness. If so, this is all the other illnesses that we will not be able to manage. Myocardial infarction or appendicitis is always an emergency, rarely a virus.

The media coverage on the coronavirus is very anxiety-provoking and it contributes to everyone’s panic.
This leads to the craziest conspiracy theories, "they’re hiding something from us." _ Nothing is obscure, it is impossible in medicine in this digital world where scientific knowledge is immediate and without filter.
The coronavirus only (almost) kills already fragile organisms. I_ am worried that this tiny living being will only reveal the immense fractures and weaknesses of our societies. The deaths which will then be counted in millions will be those of the confrontation of individuals with the total indifference to the collective interest.

Gilbert DERAY, Hôpital Pitié-Salpêtrière, Paris, March 10, 2020

Read here the original French letter

To save the world, think by yourself !

JPG - 395.2 ko
Copyrighted by Hugues Aroux
Invitation to submit
Chaos : from theory to applications
A focus issue to be published in Chaos

We are pleased to announce the forthcoming publication of a new Focus Issue entitled “Chaos : From Theory to Applications” in Chaos : An Interdisciplinary Journal of Nonlinear Science to celebrate the 80th birthday of Otto E. Rössler.

Otto submitted his first paper on chaos in 1976. The Rössler system quickly became one of the prototypes on which the paradigm of chaos theory is constructed. He also introduced hyperchaos and suggested a classification of chaotic attractors. Otto E. Rössler investigated applications of chaos in various fields : chemistry, heart rhythm, biology, electronics, astrophysics, fluid mechanics

In order to celebrate his contribution to chaos theory, and in honor of his 80th birthday, this forthcoming focus issue in Chaos is devoted to showing how chaotic behaviors help to understand the reality of the world in its complexity. Contributions should try to show how the concepts of state space, attractor, first-return maps Poincaré sections, bifurcations, etc. allow for better views of the possible dynamics produced by simple as well as complex systems. Contributions can be either theoretical, numerical or experimental.

For those who met Otto E. Rössler and who would have particular recollections, we offer the opportunity to contribute to a co-authored paper in which each contributor will write about one half or one page (possibly with one picture or one figure) for providing to the community how Otto was perceived along his career. For this type of contribution, please contact Christophe Letellier.

This Focus Issue is scheduled for publication in December 2020. All submitted articles should conform to the Chaos author guidelines. Please be sure to write a lead paragraph – see guidelines for more detail. Papers will be published immediately after acceptance and will publish online in the journal and in a virtual collection dedicated to this Focus Issue.

Please let us know if you intend to contribute to this Focus Issue by FILLING OUT this survey by JANUARY 18, 2020. If so, you will receive notification when we are open for submissions and we look forward to receiving your submission by JUNE 21, 2020. Your manuscript will be reviewed within 4-6 weeks of submission.

We hope that you will be able to contribute to this exciting Focus Issue in Chaos.

With warm regards,

Guest editors :
Christophe Letellier (Rouen Normandie University, France)
Sylvain Mangiarotti (Centre d’Etudes Spatiales de la Biosphère, Toulouse, France)
Lars Folke Olsen (University of Southern Denmark, Odense )

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