Abstract In this paper, we investigate the photon sphere, shadow radius and quasinormal modes of a four-dimensional charged Einstein–Gauss–Bonnet black hole. The perturbation massless scalar field in hole’s background is adopted. are gotten by 6th order WKB approximation approach radius, respectively. When value Gauss–Bonnet coupling constant increase, values real parts increase those imaginary...

We studied the instability of regularized 4D charged Einstein-Gauss-Bonnet de-Sitter black holes under scalar perturbations. The unstable modes satisfy superradiant condition, but not all satisfying condition are unstable. occurs when cosmological constant is small and hole charge too large. Gauss-Bonnet coupling makes more both small, stable

The following is a case of Charles Bonnet syndrome in an 86-year-old woman who presented with visual hallucinations. The differential diagnosis of visual hallucinations is broad and emergency physicians should be knowledgeable of the possible etiologies.

The sum of external angles of a polygon is always constant, π 2 . There are several elementary proofs of this fact. In the similar way, there is an invariant in polyhedron that is π 4 . To see this, let us consider a regular tetrahedron as an example. Tetrahedron has four vertices. Three regular triangles gather at each vertex. Developing the tetrahedron around each vertex, there is an open ang...

We discuss the junction conditions in the context of the Randall-Sundrum model with the Gauss-Bonnet interaction. We consider the Z2 symmetric model where the brane is embedded in an AdS5 bulk, as well as a model without Z2 symmetry in which the brane (in this case called by tradition “shell”) separates two metrically different AdS5 regions. We show that the Israel junction conditions across th...

We study the properties of anti–de Sitter black holes with a Gauss-Bonnet term for various horizon topologies (k = 0, ±1) and for various dimensions, with emphasis on the less well understood k = −1 solution. We find that the zero temperature (and zero energy density) extremal states are the local minima of the energy for AdS black holes with hyperbolic event horizons. The hyperbolic AdS black ...

1 Interest of active posturography to detect age-related and early Parkinson’s disease 1 related impairments in mediolateral postural control 2 Cédrick T. Bonnet, Arnaud Delval, and Luc Defebvre 3 Dr. Cédrick T. Bonnet is member of: Laboratoire de Neurosciences Fonctionnelles et 4 Pathologies, CNRS, Université Lille, France (e-mail: [email protected]; tel: 03 20 5 44 62 81; fax: 03 2...

In four dimensions a Gauu-Bonnet term in the action corresponds to a total derivative, and it does therefore not contribute to the classical equations of motion. For higher-dimensional geometries this term has the interesting property (which it shares with other dimensionally continued Euler densities) that when the action is varied with respect to the metric, it gives rise to a symmetric, cova...

Two non-congruent surfaces that are isometric and have the same mean curvature at corresponding points are called a Bonnet pair of surfaces or simply a Bonnet pair. The interest in such pairs arises from the following considerations: One of the fundamental problems of surface theory is to find invariants which characterize surfaces geometrically. The Bonnet theorem states that a surface is dete...

The generalized Gauss-Bonnet theorem of Allendoerfer-Weil [1] and Chern [2] has played an important role in the development of the relationship between modern differential geometry and algebraic topology, providing in particular one of the primary stimuli for the theory of characteristic classes. There are now a number of proofs in the literature, from the quite sophisticated (deducing it as a ...