http://repositorio.ufc.br/handle/riufc/60 Sat, 04 Apr 2026 15:39:26 GMT 2026-04-04T15:39:26Z http://repositorio.ufc.br/handle/riufc/41765 Título: Focal decompositions for linear differential equations of the second order Autor(es): Birbrair, Lev; Sobolevsky, Marina; Sobolevskii, Pavel Abstract: Focal decomposition associated to an ordinary differential equation of the second order is a partition of the set of all two-points boundary value problems according to the number of their solutions. Two equations are called focally equivalent if there exists a homomorphism of the set of two-points problems to itself such that the image of the focal decomposition associated to the first equation is a focal decomposition associated to the second one. In this paper, we present a complete classification for linear second-order equations with respect to this equivalence relation. Tipo: Artigo de Periódico Wed, 01 Jan 2003 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/41765 2003-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/40851 Título: Extended uncertainty from first principles Autor(es): Costa Filho, Raimundo Nogueira; Braga, João Philipe Macedo; Lira, Jorge Herbert Soares de; Andrade Júnior, José Soares de Abstract: A translation operator acting in a space with a diagonal metric is introduced to describe the motion of a particle in a quantum system. We show that the momentum operator and, as a consequence, the uncertainty relation now depend on the metric. It is also shown that, for any metric expanded up to second order, this formalism naturally leads to an extended uncertainty principle (EUP) with a minimum momentum dispersion. The Ehrenfest theorem is modified to include an additional term related to a tidal force arriving from the space curvature introduced by the metric. For one-dimensional systems, we show how to map a harmonic potential to an effective potential in Euclidean space using different metrics. Tipo: Artigo de Periódico Fri, 01 Jan 2016 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/40851 2016-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/40845 Título: Isometric deformation of surfaces in R 3 preserving the mean curvature function Autor(es): Colares, Antonio Gervásio; Kenmotsu, Katsuei Abstract: The purpose of this paper is to classify surfaces in Euclidean 3- space with constant Gaussian curvature which admit non-trivial oneparameter families of isometric immersions preserving the mean curvature function. It is shown that the Gaussian curvature must be zero and, if the mean curvature is not constant, then such isometric immersions are some deformations of the cylinder over a logarithmic spiral. Tipo: Artigo de Periódico Sun, 01 Jan 1989 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/40845 1989-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/40802 Título: Existence of nonparametric solutions for a capillary problem in warped products Autor(es): Lira, Jorge Herbert Soares de; Wanderley, Gabriela Albuquerque Abstract: We prove that there exist solutions for a nonparametric capillary problem in a wide class of Riemannian manifolds endowed with a Killing vector field. In other terms, we prove the existence of Killing graphs with prescribed mean curvature and prescribed contact angle along its boundary. These results may be useful for modeling stationary hypersurfaces under the influence of a nonhomogeneous gravitational field defined over an arbitrary Riemannian manifold. Tipo: Artigo de Periódico Wed, 01 Jan 2014 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/40802 2014-01-01T00:00:00Z