the paper is concerned with the bifurcation of limit cycles in general quadratic perturbations of a quadratic reversible and non-hamiltonian system, whose period annulus is bounded by an elliptic separatrix related to a singularity at infinity in the poincar'{e} disk. attention goes to the number of limit cycles produced by the period annulus under perturbations. by using the appropriate p...

The paper is concerned with the bifurcation of limit cycles in general quadratic perturbations of a quadratic reversible and non-Hamiltonian system, whose period annulus is bounded by an elliptic separatrix related to a singularity at infinity in the poincar'{e} disk. Attention goes to the number of limit cycles produced by the period annulus under perturbations. By using the appropriate Picard...

The paper is concerned with the bifurcation of limit cycles in general quadratic perturbations of a quadratic reversible and non-Hamiltonian system, whose period annulus is bounded by an elliptic separatrix related to a singularity at infinity in the Poincaré disk. Attention goes to the number of limit cycles produced by the period annulus under perturbations. By using the appropriate Picard-Fu...

INTRODUCTION Mitral valve repair is the treatment of choice to correct mitral insufficiency, although the literature related to mitral valve annulus behavior after mitral repair without use of prosthetic rings is scarce. OBJECTIVE To analyze mitral annulus morphology and function using real time tridimensional echocardiography in individuals submitted to mitral valve repair with Double Teflon...

We prove that perturbing the periodic annulus of reversible quadratic polynomial differential system $\dot x=y+ax^2$ , y=-x$ with a ≠ 0 inside class all systems we can obtain at most two limit cycles, including their multiplicities. Since first integral unperturbed contains an exponential function, traditional methods cannot be applied, except in Figuerasa, Tucker and Villadelprat (2013, J. Dif...

Let Π be an open, relatively compact period annulus of real analytic vector field X0 on an analytic surface. We prove that the maximal number of limit cycles which bifurcate from Π under a given multiparameter analytic deformation Xλ of X0 is finite, provided that X0 is either Hamiltonian, or generic Darbouxian vector field. 1 Statement of the result Let S be a real analytic surface without bor...