Second order Boltzmann-Gibbs principle for polynomial functions and applications

In this paper we give a new proof of the second order Boltzmann-Gibbs principle. The proof does not impose the knowledge on the spectral gap inequality for the underlying model and it relies on a proper decomposition of the antisymmetric part of the current of the system in terms of polynomial functions. In addition, we fully derive the convergence of the equilibrium fluctuations towards 1) a trivial process in case of supper-diffusive systems, 2) an Ornstein-Uhlenbeck process or the unique energy solution of the stochastic Burgers equation, in case of weakly asymmetric diffusive systems. Examples and applications are presented for weakly and partial asymmetric exclusion processes, weakly asymmetric speed change exclusion processes and hamiltonian systems with exponential interactions

Crossover to the stochastic Burgers equation for the WASEP with a slow bond

We consider the weakly asymmetric simple exclusion process in the presence of a slow bond and starting from the invariant state, namely the Bernoulli product measure of parameter $\rho\in(0,1)$. The rate of passage of particles to the right (resp. left) is $\frac1{\vphantom{n^\beta}2}+\frac{a}{2n^{\vphantom{\beta}\gamma}}$ (resp. $\frac1{\vphantom{n^\beta}2}-\frac{a}{2n^{\vphantom{\beta}\gamma}}$) except at the bond of vertices $\{-1,0\}$ where the rate to the right (resp. left) is given by $\frac{\alpha}{2n^\beta}+\frac{a}{2n^{\vphantom{\beta}\gamma}}$ (resp. $\frac{\alpha}{2n^\beta}-\frac{a}{2n^{\vphantom{\beta}\gamma}}$). Above, $\alpha>0$, $\gamma\geq \beta\geq 0$, $a\geq 0$. For $\beta<1$, we show that the limit density fluctuation field is an Ornstein-Uhlenbeck process defined on the Schwartz space if $\gamma>\frac12$, while for $\gamma = \frac12$ it is an energy solution of the stochastic Burgers equation. For $\gamma\geq\beta=1$, it is an Ornstein-Uhlenbeck process associated to the heat equation with Robin's boundary conditions. For $\gamma\geq\beta> 1$, the limit density fluctuation field is an Ornstein-Uhlenbeck process associated to the heat equation with Neumann's boundary conditions

Interpolation process between standard diffusion and fractional diffusion

We consider a Hamiltonian lattice field model with two conserved quantities, energy and volume, perturbed by stochastic noise preserving the two previous quantities. It is known that this model displays anomalous diffusion of energy of fractional type due to the conservation of the volume [5, 3]. We superpose to this system a second stochastic noise conserving energy but not volume. If the intensity of this noise is of order one, normal diffusion of energy is restored while it is without effect if intensity is sufficiently small. In this paper we investigate the nature of the energy fluctuations for a critical value of the intensity. We show that the latter are described by an Ornstein-Uhlenbeck process driven by a L\'evy process which interpolates between Brownian motion and the maximally asymmetric 3/2-stable L\'evy process. This result extends and solves a problem left open in [4].Comment: to appear in AIHP

Nonlinear Perturbation of a Noisy Hamiltonian Lattice Field Model: Universality Persistence

In [2] it has been proved that a linear Hamiltonian lattice field perturbed by a conservative stochastic noise belongs to the 3/2-L\'evy/Diffusive universality class in the nonlinear fluctuating theory terminology [15], i.e. energy superdiffuses like an asymmetric stable 3/2-L\'evy process and volume like a Brownian motion. According to this theory this should remain valid at zero tension if the harmonic potential is replaced by an even potential. In this work we consider a quartic anharmonicity and show that the result obtained in the harmonic case persists up to some small critical value of the anharmonicity

Farming exposure and asthma phenotypes:In mice and men

Although several studies have shown that farmers and people with agricultural-related occupations have a higher risk of developing lung diseases such as nonallergic asthma, chronic bronchitis and chronic obstructive pulmonary disease (COPD), it has also been shown that exposure to the farm environment is associated with a protective effect on the development of atopy and allergic asthma.In this thesis, both effects of farm exposures on the immune system were studied: the protective effect against allergic asthma and the induction of non-allergic asthma. These studies were conducted among agricultural workers, and in mouse models of allergic and nonallergic lung disease. In addition, the presence of several macrophage phenotypes in animal models of allergic and non-allergic asthma was investigated, as well as the effects of exposure to farm dust extract on a macrophage cell line.This thesis demonstrated that occupational exposure to a farm environment and exposure to farm dust extracts in mice lead to a shift in the immune system towards non-allergic inflammation. This shift offers on the one hand protection against development of allergic diseases, such as allergic asthma, but is also associated with the risk of nonallergic asthma development. In addition, this thesis shows that, within the various phenotypes asthma, various inflammatory mediators and cells are important in the development and severity of airway hyperresponsiveness