DSpace Coleção:
http://www.repositorio.ufc.br/handle/riufc/60
2019-04-25T09:50:31ZExtended uncertainty from first principles
http://www.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.2016-01-01T00:00:00ZIsometric deformation of surfaces in R 3 preserving the mean curvature function
http://www.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.1989-01-01T00:00:00ZExistence of nonparametric solutions for a capillary problem in warped products
http://www.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.2014-01-01T00:00:00ZOn the proof of the thin sandwich conjecture in arbitrary dimensions
http://www.repositorio.ufc.br/handle/riufc/40756
Título: On the proof of the thin sandwich conjecture in arbitrary dimensions
Autor(es): Avalos, Rodrigo; Dahia, Fábio Leal de Melo; Romero, Carlos; Lira, Jorge Herbert Soares de
Abstract: On the proof of the Thin Sandwich Conjecture in arbitrary dimensions. In this paper we show the validity, under certain geometric conditions, of Wheeler's thin sandwich conjecture for higher dimensional theories of gravity. We extend the results shown by R. Bartnik and G. Fodor for the 3-dimensional case in two ways.On the one hand, we show that the results presented in Phys. Rev. D 48, 3596-3599 (1993) are valid in arbitrary dimensions, and on the other hand, we show that the geometric hypotheses needed for the proofs can always be satisfied, which constitutes in itself a new result for the 3-dimensional case. In this way, we show that on any compact n-dimensional manifold, n ≥ , there is an open set in the space of all possible initial data where the thin sandwich problem is well-posed.2017-01-01T00:00:00Z