1,721,057 research outputs found

    Normal geodesics in static spacetimes with critical asymptotic behavior

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    This paper deals with the existence of normal geodesics joining two given submanifolds in a static spacetime when the coefficient of its metric has a quadratic growth. A suitable variational approach allows one to use the classical Ljusternik-Schnirelman theory

    Lightlike periodic trajectories in Space-Times

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    Let z_z be a Lorentz metric on a manifold \m = \mo \times \r such that \mo is not compact. We prove the existence of infinitely many lightlike periodic trajectories in \m by using variational methods and Ljusternik-Schnirelman theory

    Multiplicity results for some quasilinear equations in lack of symmetry

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    In this paper we prove the existence of multiple nontrivial solutions for the quasilinear equation in divergence form div(a(x,u,u))+At(x,u,u)=λb(x,u)g(x,u)  in Ω,u=0  on Ω, - {\rm div} (a(x,u,\nabla u)) + A_t(x,u,\nabla u) = \lambda b(x,u) - g(x,u) \;\hbox{in $\Omega$,}\quad u = 0\; \hbox{on $\partial\Omega$,} in an open bounded domain ΩRN\Omega \subset \R^N, where A:Ω×R×RNRA :\Omega \times \R \times \R^N \to \R is a given Carathéodory function with partial derivatives At(x,t,ξ)=At(x,t,ξ)A_t(x,t,\xi) = \frac{\partial A}{\partial t}(x,t,\xi) and a(x,t,ξ)=(Aξ1(x,t,ξ),,AξN(x,t,ξ))a(x,t,\xi) = (\frac{\partial A}{\partial \xi_1}(x,t,\xi),\dots,\frac{\partial A}{\partial \xi_N}(x,t,\xi)). It generalizes the pp-Laplacian problem Δpu=λup2ug(x,u),uW01,p(Ω), - \Delta_p u = \lambda |u|^{p-2}u - g(x,u), \qquad u \in W^{1,p}_0(\Omega), but, in general, the corresponding functional is not well defined in all the space W01,p(Ω)W^{1,p}_0(\Omega). Anyway, under suitable assumptions and by using variational tools, we are able to prove that the number of solutions of (Pλ)(P_\lambda) depends on the parameter λ\lambda and, even in lack of symmetry, at least three nontrivial solutions exist if λ\lambda is large enough

    Normal trajectories in stationary spacetimes with critical asymptotic behavior

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    The aim of this note is to study the existence of normal trajectories joining two given submanifolds under the action of an external field in a standard stationary spacetime. Here, it is assumed that both the growth of the potential and that one of the coefficients of the metric are critical in a suitable sense

    Periodic solutions for dynamical systems on non-complete Riemannian manifolds

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    We look for periodic solutions for a dynamical system on a non-complete Riemannian manifold. If the potential is bounded and suitable convexity assumptions hold, the existence of infinitely many solutions can be proved by means of variational methods, penalization arguments and classical Ljusternik-Schnirelman theory

    Multiple solitary waves for non-homogeneous Schrödinger-Maxwell equations

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    The aim of this paper is investigating the existence of standing waves which are solutions of a nonlinear Schroedinger equation coupled with Maxwell's equations when a non--homogeneous term breaks the symmetry of the associated functional

    Light rays joining two submanifolds in Space-Times

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    Let \m = \mo \times \Rrset be a stationary Lorentz metric and P0P_0, P1P_1 be two closed submanifolds of \mo. By using the Ljusternik-Schnirelman theory and variational tools, we prove the influence of the topology of P0P_0 and P1P_1 on the number of lightlike geodesics in \m joining P0×{0}P_0 \times \{0\} to P_1 \times \Rrset

    Positive solutions for some generalized p–Laplacian type problems

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    In this paper, we prove the existence of nontrivial weak bounded solutions of the nonlinear elliptic problem{-div(a(x, u, del u)) + A(t)(x, u, del u) = f(x, u) in Omega, u >= 0 in Omega, u = 0 on partial derivative Omega,where Omega subset of R-N is an open bounded domain, N >= 3, and A(x, t, xi), f(x, t) are given functions, with A(t) = partial derivative A/partial derivative t, a = del xi A,To this aim, we use variational arguments which are adapted to our setting and exploit a weak version of the Cerami-Palais-Smale condition.Furthermore, if A(x, t, xi) grows fast enough with respect to t, then the nonlinear term related to f(x, t) may have also a supercritical growth

    Soliton solutions for quasilinear modified Schrödinger equations in applied sciences

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    In this paper, we prove the existence of nontrivial weak bounded solutions of the quasilinear modified Schrödinger problem {div(g2(u)u)+g(u)g(u)u2+V(x)u=f(x,u)amp;in R3,ugt;0amp;in R3, \left\{ \begin{array}{ll} -{\rm div}(g^2(u) \nabla u) + g(u) g^{\prime}(u) |\nabla u|^2 + V(x) u = f(x, u) &\hbox{in $\R^3$,}\\ u > 0 &\hbox{in $\R^3$,} \end{array}\right. where V:R3RV:\R^3\to\R, f:R3×RRf:\R^3\times\R\to\R are ``good'' functions and g:RRg:\R\to\R is such that g2(u)=1+[(l(u2))]22g^2(u)= 1+\frac{[(l(u^2))^{\prime}]^2}{2} for a given lC2(R)l\in\mathcal{C}^2(\R). By means of variational methods and an approximation argument, here we obtain an existence result for the superfluid film equation in Plasma Physics and for the equation which models the self-channelling of a high-power ultrashort laser, which derive from our model problem by taking l(s)=sl(s)=s, respectively l(s)=1+sl(s)=\sqrt{1+s}, in the previous definition of g2(u)g^2(u)
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