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Focusing of spherical nonlinear pulses in R1+3. II. Nonlinear caustic.

Rémi Carles, Jeffrey Rauch (2004)

Revista Matemática Iberoamericana

We study spherical pulse like families of solutions to semilinear wave equattions in space time of dimension 1+3 as the pulses focus at a point and emerge outgoing. We emphasize the scales for which the incoming and outgoing waves behave linearly but the nonlinearity has a strong effect at the focus. The focus crossing is described by a scattering operator for the semilinear equation, which broadens the pulses. The relative errors in our approximate solutions are small in the L∞ norm.

Free decay of solutions to wave equations on a curved background

Serge Alinhac (2005)

Bulletin de la Société Mathématique de France

We investigate for which metric g (close to the standard metric g 0 ) the solutions of the corresponding d’Alembertian behave like free solutions of the standard wave equation. We give rather weak (i.e., non integrable) decay conditions on g - g 0 ; in particular, g - g 0 decays like t - 1 2 - ε along wave cones.

Fundamental solutions and asymptotic behaviour for the p-Laplacian equation.

Soshana Kamin, Juan Luis Vázquez (1988)

Revista Matemática Iberoamericana

We establish the uniqueness of fundamental solutions to the p-Laplacian equationut = div (|Du|p-2 Du),   p > 2,defined for x ∈ RN, 0 < t < T. We derive from this result the asymptotic behavoir of nonnegative solutions with finite mass, i.e., such that u(*,t) ∈ L1(RN). Our methods also apply to the porous medium equationut = ∆(um),   m > 1,giving new and simpler proofs of known results. We finally introduce yet another method of proving asymptotic results based on the...

Geometric optics and instability for NLS and Davey-Stewartson models

Rémi Carles, Eric Dumas, Christof Sparber (2012)

Journal of the European Mathematical Society

We study the interaction of (slowly modulated) high frequency waves for multi-dimensional nonlinear Schrödinger equations with Gauge invariant power-law nonlinearities and nonlocal perturbations. The model includes the Davey-Stewartson system in its elliptic-elliptic and hyperbolic-elliptic variants. Our analysis reveals a new localization phenomenon for nonlocal perturbations in the high frequency regime and allows us to infer strong instability results on the Cauchy problem in negative order Sobolev...

Global and exponential attractors for a Caginalp type phase-field problem

Brice Bangola (2013)

Open Mathematics

We deal with a generalization of the Caginalp phase-field model associated with Neumann boundary conditions. We prove that the problem is well posed, before studying the long time behavior of solutions. We establish the existence of the global attractor, but also of exponential attractors. Finally, we study the spatial behavior of solutions in a semi-infinite cylinder, assuming that such solutions exist.

Global Asymptotic Stability of Equilibria in Models for Virus Dynamics

J. Prüss, R. Zacher, R. Schnaubelt (2008)

Mathematical Modelling of Natural Phenomena

In this paper several models in virus dynamics with and without immune response are discussed concerning asymptotic behaviour. The case of immobile cells but diffusing viruses and T-cells is included. It is shown that, depending on the value of the basic reproductive number R0 of the virus, the corresponding equilibrium is globally asymptotically stable. If R0 < 1 then the virus-free equilibrium has this property, and in case R0 > 1 there is a unique disease equilibrium which takes over this...

Global attractivity, oscillation and Hopf bifurcation for a class of diffusive hematopoiesis models

Xiao Wang, Zhixiang Li (2007)

Open Mathematics

In this paper, we discuss the special diffusive hematopoiesis model ∂ P ( t , x ) ∂ t = Δ P ( t , x ) - γ P ( t , x ) + β P ( t - τ , x ) 1 + P n ( t - τ , x ) with Neumann boundary condition. Sufficient conditions are provided for the global attractivity and oscillation of the equilibrium for Eq. (*), by using a new theorem we stated and proved. When P(t, χ) does not depend on a spatial variable χ ∈ Ω, these results are also true and extend or complement existing results. Finally, existence and stability of the Hopf bifurcation for Eq. (*) are studied.

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