https://repositorio.ufba.br/handle/ri/5202 2026-04-17T13:02:40Z https://repositorio.ufba.br/handle/ri/17237 Hitchin–Thorpe inequality and Kaehler metrics for compact almost Ricci soliton Brasil, A.; Costa, E.; Ribeiro Jr., E. The purpose of this paper is to prove a Hitchin–Thorpe inequality for a four-dimensional compact almost Ricci soliton. Moreover, we prove that under a suitable integral condition, a four-dimensional compact almost Ricci soliton is isometric to standard sphere. Finally, we prove that under a simple condition, a four-dimensional compact Ricci soliton with harmonic self-dual part of Weyl tensor is either isometric to a standard sphere S4 or is Kaehler–Einstein. Artigo de Periódico 2013-01-01T00:00:00Z https://repositorio.ufba.br/handle/ri/7614 Second-order biases of maximum likelihood estimates in overdispersed generalized linear models Cordeiro, Gauss Moutinho; Botter, Denise Aparecida In this paper, we derive general formulae for second-order biases of maximum likelihood estimates in overdispersed generalized linear models, thus generalizing results by Cordeiro and McCullagh (J. Roy. Statist. Soc. Ser. B 53 (1991) 629), and Botter and Cordeiro (Statist. Comput. Simul. 62 (1998) 91). Our formulae cover many important and commonly used models and are easily implemented by means of supplementary weighted linear regressions. They are also simple enough to be used algebraically to obtain several closed-form expressions in special models. The practical use of such formulae is illustrated in a simulation study. Artigo de Periódico 2001-01-01T00:00:00Z https://repositorio.ufba.br/handle/ri/6219 A Comparative analysis of Green’s functions of 1D matching equations for motion synthesis Ferreira Júnior, Perfilino Eugênio; Torreão, José R. A.; Carvalho, Paulo Cezar Pinto When filtering an input image, the Green’s functions of matching equations are capable of inducing a broad class of motions, a property that has led to their use in several computer graphics and computer vision applications. In all such applications, the Green’s functions of second-order differential equations have been considered, even though no justification has been given for their preference over simpler, first-order equations. Here we present a study of first-order one-dimensional matching equations, both in the uniform and in the affine motion models. Comparing their Green’s functions with those of the corresponding second-order cases, we find evidence for the latter’s superiority in motion synthesis. We also propose and discuss a general discretization scheme for Green’s functions of one-dimensional matching equations, showing that the affine motion model is particularly sensitive to the sampling frequency. In this case, we advocate the use of area sampling, for allowing realistic motion simulations. Elsevier Artigo de Periódico 2009-10-15T00:00:00Z