Dynamics of wealth inequality
Publication date: Available online 13 June 2019Source: Comptes Rendus PhysiqueAuthor(s): Zdzislaw Burda, Pawel Wojcieszak, Konrad ZuchniakAbstractWe study an agent-based model of evolution of wealth distribution in a macroeconomic system. The evolution is driven by multiplicative stochastic fluctuations governed by the law of proportionate growth and interactions between agents. We are mainly interested in interactions increasing wealth inequality, that is, in a local implementation of the accumulated advantage principle. Such interactions destabilise the system. They are confronted in the model with a global regulatory me...
Source: Comptes Rendus Physique - June 13, 2019 Category: Physics Source Type: research
A novel nonlinear least-squares approach to highly maneuvering target tracking
Publication date: Available online 11 June 2019Source: Comptes Rendus PhysiqueAuthor(s): Marion Pilté, Silvère Bonnabel, Frédéric LivernetAbstractTrajectories of aerial and marine vehicles are typically made of a succession of smooth trajectories, linked by abrupt changes, i.e. maneuvers. Notably, modern highly maneuvering targets are capable of very brutal changes in the heading, with accelerations of up to 15g. As a result, we model the target behavior using piecewise deterministic Markov models, driven by parameters that jump at unknown times. Over the past years, real-time (or incremental) optimization-based smooth...
Source: Comptes Rendus Physique - June 12, 2019 Category: Physics Source Type: research
Towards a statistical mechanics of cities
Publication date: Available online 11 June 2019Source: Comptes Rendus PhysiqueAuthor(s): Luís M.A. BettencourtAbstractCities are some of the most complex dynamical systems in human societies and in nature. There is growing interest in producing more comprehensive quantitative theory, capable of describing many of the features now observable in urban environments, especially those that show empirical regularities across cities of different sizes, geographies, and levels of development. The principal challenge of achieving such a goal is our ability to build frameworks that include realistic but simple accounts of agents' c...
Source: Comptes Rendus Physique - June 12, 2019 Category: Physics Source Type: research
Editorial Board
Publication date: January–February 2019Source: Comptes Rendus Physique, Volume 20, Issues 1–2Author(s): (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - June 7, 2019 Category: Physics Source Type: research
Dossier Sommaire
Publication date: January–February 2019Source: Comptes Rendus Physique, Volume 20, Issues 1–2Author(s): (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - June 7, 2019 Category: Physics Source Type: research
The French Academy of Sciences and the systems of units: A long history!
Publication date: January–February 2019Source: Comptes Rendus Physique, Volume 20, Issues 1–2Author(s): Christophe Salomon, Christian Bordé, Pierre Fayet (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - June 7, 2019 Category: Physics Source Type: research
Differential received power measurements over off-body links for obstruction-resilient pedestrian navigation
Publication date: Available online 6 June 2019Source: Comptes Rendus PhysiqueAuthor(s): Bernard Uguen, Benoît Denis, Raffaele D'Errico, Nicolas AmiotAbstractIn this paper, we aim at improving pedestrian navigation experience based on standard narrow-band wireless technologies and simple radio metrics. The proposed solution takes benefits from body shadowing effects traditionally experienced at body-worn devices, for instance over off-body radio links with respect to fixed elements of infrastructure. The main idea is to infer relative angular information between the carrying body's heading and the received signal's directi...
Source: Comptes Rendus Physique - June 7, 2019 Category: Physics Source Type: research
Low-temperature marginal ferromagnetism explains anomalous scale-free correlations in natural flocks
Publication date: Available online 5 June 2019Source: Comptes Rendus PhysiqueAuthor(s): Andrea Cavagna, Antonio Culla, Luca Di Carlo, Irene Giardina, Tomas S. GrigeraAbstractWe introduce a new ferromagnetic model capable of reproducing one of the most intriguing properties of collective behaviour in starling flocks, namely the fact that strong collective order coexists with scale-free correlations of the modulus of the microscopic degrees of freedom, that is, the birds' speeds. The key idea of the new theory is that the single-particle potential needed to bound the modulus of the microscopic degrees of freedom around a fin...
Source: Comptes Rendus Physique - June 6, 2019 Category: Physics Source Type: research
Modeling cities
Publication date: Available online 3 June 2019Source: Comptes Rendus PhysiqueAuthor(s): Marc BarthelemyAbstractCities are systems with a large number of constituents and agents interacting with each other and can be considered as emblematic of complex systems. Modeling these systems is a real challenge and triggered the interest of many disciplines such as quantitative geography, spatial economics, geomatics and urbanism, and more recently physics. (Statistical) Physics plays a major role by bringing tools and concepts able to bridge theory and empirical results, and we will illustrate this on some fundamental aspects of c...
Source: Comptes Rendus Physique - June 5, 2019 Category: Physics Source Type: research
Statistical Physics Of Opinion Formation: Is it a SPOOF?
We describe relations between models of opinion formation, developed by physicists, and theoretical models of social response, known in social psychology. We draw attention to issues that are interesting for social psychologists and physicists. We show examples of studies directly inspired by social psychology like: “independence vs. anticonformity” or “personality vs. situation”. We summarize the results that have been already obtained and point out what else can be done, also with respect to other models in SPOOF. Finally, we demonstrate several analytical methods useful in SPOOF, such as the concept of effective...
Source: Comptes Rendus Physique - May 25, 2019 Category: Physics Source Type: research
Herding and idiosyncratic choices: Nonlinearity and aging-induced transitions in the noisy voter model
Publication date: Available online 24 May 2019Source: Comptes Rendus PhysiqueAuthor(s): Oriol Artime, Adrián Carro, Antonio F. Peralta, José J. Ramasco, Maxi San Miguel, Raúl ToralAbstractWe consider the herding-to-non-herding transition caused by idiosyncratic choices or imperfect imitation in the context of the Kirman Model for financial markets, or equivalently the Noisy Voter Model for opinion formation. In these original models, this is a finite-size transition that disappears for a large number of agents. We show how the introduction of two different mechanisms makes this transition robust and well defined. A firs...
Source: Comptes Rendus Physique - May 25, 2019 Category: Physics Source Type: research
Discovery of quasicrystals: The early days
Publication date: Available online 23 May 2019Source: Comptes Rendus PhysiqueAuthor(s): Denis Gratias, Marianne QuiquandonAbstractThis paper is a survey of the initial developments of the research on quasicrystals starting from their discovery by Daniel Shechtman (Nobel Prize in Chemistry in 2011) in 1982 at the National Bureau of Standards (now National Institute for Standard and Technology) in Gaithersburg (Maryland, USA) up to the beginning of the early 1990s, a time when the crystallographic methods were well developed and mastered enough to decipher the ultimate atomic structures of quasicrystals. These early works ha...
Source: Comptes Rendus Physique - May 24, 2019 Category: Physics Source Type: research
The birth of the research on the magnetic confinement for nuclear fusion
Publication date: Available online 21 May 2019Source: Comptes Rendus PhysiqueAuthor(s): Guy LavalAbstractAt their very beginning, the researches on the magnetic confinement fusion had to face up plasma instabilities. Macroscopic plasma instabilities were the first ones to be identified and they were found to be very harmful for plasma confinement. During the first years after the Atoms for Peace Meeting in 1958, the main goals of experimental and theoretical researches dealt with their suppression or control. During this period, two special types of instabilities, the localized interchange modes and the tearing modes, were...
Source: Comptes Rendus Physique - May 22, 2019 Category: Physics Source Type: research
Foreword
Publication date: Available online 17 May 2019Source: Comptes Rendus PhysiqueAuthor(s): Jean-Philippe Bouchaud, Jean-Pierre Nadal (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - May 18, 2019 Category: Physics Source Type: research
