99,382 research outputs found
Analytic solution of the algebraic equation associated to the Ricci tensor in extended Palatini gravity
In this work we discuss the exact solution to the algebraic equation
associated to the Ricci tensor in the quadratic extension of Palatini
gravity. We show that an exact solution always exists, and in the general case
it can be found by a simple matrix diagonalization. Furthermore, the general
implications of the solution are analysed in detail, including the generation
of an effective cosmological constant, and the recovery of the and
theories as particular cases in their corresponding limit. In addition,
it is proposed a power series expansion of the solution which is successfully
applied to the case of the electromagnetic field. We show that this power
series expansion may be useful to deal perturbatively with some problems in the
context of Palatini gravity.Comment: arXiv admin note: text overlap with arXiv:1101.3864, arXiv:1306.6537,
arXiv:1112.2223 by other author
Ant routing algorithm for the Lightning Network
We propose a decentralized routing algorithm that can be implemented in
Bitcoin Lightning Network. All nodes in the network contribute equally to path
searching. The algorithm is inspired from ant path searching algorithms.Comment: 10 pages, 1 figur
Polar optical phonons in core-shell semiconductor nanowires
We obtain the the long-wavelength polar optical vibrational modes of
semiconductor core-shell nanowires by means of a phenomenological continuum
model. A basis for the space of solutions is derived, and by applying the
appropriate boundary conditions, the transcendental equations for the coupled
and uncoupled modes are attained. Our results are applied to the study of the
GaAs-GaP core-shell nanowire, for which we calculate numerically the polar
optical modes, analyzing the role of strain in the vibrational properties of
this nanosystem
- âŠ