Search results for "54"
showing 10 items of 2200 documents
An attempt to classification of the quasi rational solutions to the NLS equation
2015
Based on a representation in terms of determinants of order 2N , an attempt to classification of quasi rational solutions to the one dimensional focusing nonlinear Schrödinger equation (NLS) is given and several conjectures about the structure of the solutions are also formulated. These solutions can be written as a product of an exponential depending on t by a quotient of two polynomials of degree N (N + 1) in x and t depending on 2N −2 parameters. It is remarkable to mention that in this representation, when all parameters are equal to 0, we recover the PN breathers.
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.
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.
Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in 254Rf
2015
International audience; Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247(73) mu s have been discovered in the heavy (254)Rf nucleus. The observation of the shorter-lived isomer was made possible by a novel application of a digital data acquisition system. The isomers were interpreted as the K-pi = 8(-), nu(2)(7/2(+)[624]; 9/2(-)[734]) two-quasineutron and the K-pi = 16(+), 8(-)nu(2)(7/2(+)[624]; 9/2(-)[734] circle times 8(-)pi(2) (7/2(-)[514]; 9/2(+)[624]) four-quasiparticle configurations, respectively. Surprisingly, the lifetime of the two-quasiparticle isomer is more than 4 orders of magnitude shorter than what has been observed for analogous isomer…
La gestion des betteraves adventices résistantes à un herbicide: une approche par simulation
2007
National audience; Les variétés de betteraves sucrières génétiquement modifiées (GM) résistantes à un herbicide sont, a priori, intéressantes dans des champs fortement infestés par la betterave adventice. Cependant, la montée à fleurs de ces betteraves GM peut entraîner l’apparition d’individus résistants, via la dispersion de pollen. Nous avons développé et utilisé le modèle GENESYS-Betterave pour simuler, à l’échelle d’une petite région agricole, l’impact des pratiques culturales sur la dispersion du transgène. Il permet d'identifier des stratégies pour contrôler les adventices et limiter l'apparition de populations résistantes en zone de production de betterave sucrière. L’utilisation de…
Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei
2008
Data collected by the Pierre Auger Observatory provide evidence for anisotropy in the arrival directions of the cosmic rays with the ighest-energies, which are correlated with the positions of relatively nearby active galactic nuclei (AGN) [Pierre Auger Collaboration, Science 318 (2007) 938]. The correlation has maximum significance for cosmic rays with energy greater than ~6 x 1019 eV and AGN at a distance less than ~75 Mpc. We have confirmed the anisotropy at a confidence level of more than 99% through a test with parameters specified a priori, using an independent data set. The observed correlation is compatible with the hypothesis that cosmic rays with the highest-energies originate fro…
Zenith distribution and flux of atmospheric muons measured with the 5-line ANTARES detector
2010
The ANTARES high energy neutrino telescope is a three-dimensional array of about 900 photomultipliers distributed over 12 mooring lines installed in the Mediterranean Sea. Between February and November 2007 it acquired data in a 5-line configuration. The zenith angular distribution of the atmospheric muon flux and the associated depth-intensity relation are measured and compared with previous measurements and Monte Carlo expectations. An evaluation of the systematic effects due to uncertainties on environmental and detector parameters is presented.
Cropping system dynamics, climate variability, and seed losses among East African smallholder farmers: a retrospective survey.
2014
Abstract Climate variability directly affects traditional low input and rain-fed farming systems, but few studies have paid attention retrospectively to the cropping system’s ability to mitigate climate risk. This study analyzes the impacts of rainfall variability on farmers’ seed variety losses over time, considering changes in smallholder farming systems. The cropping system dynamics, in favoring maize at the expense of sorghum and pearl millet, have induced an increasing risk of seed loss during drought. Combining ecological anthropology and climatology, a retrospective survey asking farmers about the period 1961–2006 was carried out at three altitudinal levels (750, 950, and 1100 m) on …
Résumé des recherches sur les bioagresseurs du riz pluvial
2009
La recherche a été menée sur plusieurs fronts ces dernières campagnes pour la lutte durable contre les bioagresseurs du riz pluvial. Elle s'est orientée vers l'exploitation de la biodiversité des plantes et la recherche de systèmes de culture pour gérer les " vers blancs " ou " scarabées noirs " (Coleoptera, Scarabaeidae), les foreurs de tiges, la pyriculariose et le striga. Les résultats des essais réalisés avec le projet BVlac sur l'utilisation du champignon entomopathogène Metarhizium anisopliae ainsi que les résultats des essais menés avec l'ONG Tafa sur la lutte contre le striga dans différents systèmes de culture seront présentés par ailleurs. Nous rapporterons ici les recherchés mené…