A relation between the right triangle and circular tori with constant mean curvature in the unit 3-sphere

Autor: Abdênago Barros

Publikováno v: Anais da Academia Brasileira de Ciências, Vol 76, Iss 4, Pp 639-643 (2004)

In this note we will show that the inverse image under the stereographic projection of a circular torus of revolution in the 3-dimensional euclidean space has constant mean curvature in the unit 3-sphere if and only if their radii are the catet and t

Externí odkaz: https://doaj.org/article/17b91d32719043f3970652e68616d5aa

Gradient estimate for eigenfunctions of the operator Δ

Autor: Abdênago Barros, Antônio Kelson Silva

Publikováno v: Differential Geometry and its Applications. 60:147-155

The aim of this paper is to present a gradient estimate for eigenfunctions associated to the operator Δ V on a Riemannian manifold with m-Bakry–Emery–Ricci tensor bounded from below. As a consequence of this estimate we obtain a Harnack type ine

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::c7146827d0e22f2ea26793fc11f259a2
https://doi.org/10.1016/j.difgeo.2018.06.004

A new characterization of the Euclidean sphere

Autor: José N. V. Gomes, Cícero P. Aquino, Abdênago Barros

Publikováno v: Anais da Academia Brasileira de Ciências, Volume: 90, Issue: 3, Pages: 2663-2670, Published: SEP 2018
Anais da Academia Brasileira de Ciências v.90 n.3 2018
Anais da Academia Brasileira de Ciências
Academia Brasileira de Ciências (ABC)
instacron:ABC
Anais da Academia Brasileira de Ciências, Vol 90, Iss 3, Pp 2663-2670

In this paper, we obtain a new characterization of the Euclidean sphere as a compact Riemannian manifold with constant scalar curvature carrying a nontrivial conformal vector field which is also conformal Ricci vector field.

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::354fc8a6b2aaf75a693172356f289af9
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652018000602663&lng=en&tlng=en

Rigidity in dimension four of area-minimising Einstein manifolds

Autor: Abdênago Barros, P. A. Sousa, R. M. Batista, C. Cruz

Publikováno v: Mathematical Proceedings of the Cambridge Philosophical Society. 158:355-363

The aim of this paper is to prove a sharp inequality for the area of a four dimensional compact Einstein manifold (Σ,gΣ) embedded into a complete five dimensional manifold (M5,g) with positive scalar curvatureRand nonnegative Ricci curvature. Under

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::af756decb4db843ec1d6246d15ad7273
https://doi.org/10.1017/s030500411500002x

Characterizations and integral formulae for generalized m-quasi-Einstein metrics

Autor: Abdênago Barros, Ernani Ribeiro

Publikováno v: Bulletin of the Brazilian Mathematical Society, New Series. 45:325-341

The aim of this paper is to present some structural equations for generalized m-quasi-Einstein metrics (M n , g, ∇ f, λ), which was defined recently by Catino in [11]. In addition, supposing that M n is an Einstein manifold we shall show that it i

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::862627862f37e3d7b3752cc4c2856935
https://doi.org/10.1007/s00574-014-0051-0