Search results for "35"
showing 10 items of 2413 documents
N-order rational solutions to the Johnson equation depending on 2N - 2 parameter
2017
International audience; We construct rational solutions of order N depending on 2N-2 parameters. They can be written as a quotient of 2 polynomials of degree 2N(N+1) in x, t and 2N(N+1) in y depending on 2N-2 parameters. We explicitly construct the expressions of the rational solutions of order 4 depending on 6 real parameters and we study the patterns of their modulus in the plane (x,y) and their evolution according to time and parameters a1,a2,a3,b1,b2,b3.
Multi-parametric families solutions to the Burgers equation
2021
We construct 2N real parameter solutions to the Burgers' equation in terms of determinant of order N and we call these solutions, N order solutions. We deduce general expressions of these solutions in terms of exponentials and study the patterns of these solutions in functions of the parameters for N = 1 until N = 4.
Synchronization and fluctuations for interacting stochastic systems with individual and collective reinforcement
2020
The Pólya urn is the paradigmatic example of a reinforced stochastic process. It leads to a random (non degenerated) time-limit. The Friedman urn is a natural generalization whose a.s. time-limit is not random anymore. In this work, in the stream of previous recent works, we introduce a new family of (finite) systems of reinforced stochastic processes, interacting through an additional collective reinforcement of mean field type. The two reinforcement rules strengths (one componentwise, one collective) are tuned through (possibly) different rates n −γ. In the case the reinforcement rates are like n −1 , these reinforcements are of Pólya or Friedman type as in urn contexts and may thus lead …
Additive functionals and push forward measures under Veretennikov's flow
2014
16 pages; In this work, we will be interested in the push forward measure $(\vf_t)_*\gamma$, where $\vf_t$ is defined by the stochastic differential equation \begin{equation*} d\vf_t(x)=dW_t + \ba(\vf_t(x))dt, \quad \vf_0(x)=x\in\mbR^m, \end{equation*} and $\gamma$ is the standard Gaussian measure. We will prove the existence of density under the hypothesis that the divergence $\div(\ba)$ is not a function, but a signed measure belonging to a Kato class; the density will be expressed with help of the additive functional associated to $\div(\ba)$.
High-order Kerr nonlinearity of air calibrated with transient molecular alignment
2009
Talk given by O. Faucher; International audience; Nonlinear electronic Kerr index of the major air constituents has been measured up to high order terms using transient molecular alignment as a reference. Sign reversal associated to negative nonlinearity is observed above a pulse intensity of 26 TW/cm^2.
Optical properties of chlorine-and oxygen-related defects in SiO$_2$ glass and optical fibers
2018
International audience; Photoinduced processes involving chlorine molecules in synthetic silica were studied. Interstitial Cl$_2$ in SiO$_2$ are prevented from VIS/UV photolysis by cage effect. However, they react with oxygen interstitials yielding photosensitive ClClO molecules absorbing at 264nm.
Multifunctionality: refocusing a spreading, loose and fashionable concept for looking at sustainability?
2008
International audience; The notion of agriculture's Multifunctionality (MF) emerged in the 1980s. It then followed two trajectories since the 1990s: a conflicting period linked to its use in the international trade negotiations on the one hand, a spreading in terms of meaning, use and geographically on the other hand. Specific meanings appeared in connection with policy making, at national or international levels, or through the involvement of new disciplines. Yet, very few authors discuss the implication of the chosen meaning on their findings. To explore and take advantage of using this word and to deliver it from its controversial use in international trade negotiations, it is absolutely…
Urban environment during early-life and blood pressure in young children
2021
Background: The urban environment is characterised by many exposures that may influence hypertension development from early life onwards, but there is no systematic evaluation of their impact on child blood pressure (BP). Methods: Systolic and diastolic blood pressure were measured in 4,279 children aged 4-5 years from a multi-centre European cohort (France, Greece, Spain, and UK). Urban environment exposures were estimated during pregnancy and childhood, including air pollution, built environment, natural spaces, traffic, noise, meteorology, and socioeconomic deprivation index. Single- and multiple-exposure linear regression models and a cluster analysis were carried out. Results: In multi…
Nodulating symbiotic bacteria and soil quality
2005
Chapitre 9 : Plant microbe interactions and soil quality Partie : 9-2; International audience
Evaluation agroécologique de systèmes de culture en zone tropicale humide : Cas de la mise en valeur agricole d'une savane herbacée acide (Plaine des…
2013
Dans les régions tropicales humides, concilier intensification agricole et protection des ressources naturelles est un défi majeur et difficile à relever. Dans les savanes acides du nord-est laotien, des systèmes de culture de semis direct sur couverture végétale (SCV), basés sur les trois principes du non-labour, d’une couverture permanente du sol, et sur la pratique de rotations culturales diversifiées, sont proposés comme alternative technique à l’intensification agricole conventionnelle basée sur le labour. Si ces systèmes ont connu une diffusion importante et rapide dans les grandes agricultures mécanisées, leur diffusion reste néanmoins à ce jour limitée en contexte de petite agricult…