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- Manuel Maia, Miguel Méndez
- Discrete Mathematics
- 2008

We introduce two new binary operations with combinatorial species; the arithmetic product and the modified arithmetic product. The arithmetic product gives combi-natorial meaning to the product of Dirichlet series and to the Lambert series in the context of species. It allows us to introduce the notion of multiplicative species, a lifting to the… (More)

- M D Maia, A J S Capistrano, J S Alcaniz, E M Monte
- 2009

(The dynamics of the extrinsic curvature) Abstract: The acceleration of the universe is described as a dynamical effect of the extrinsic curvature of space-time. By extending previous results, the extrinsic curvature is regarded as an independent spin-2 field, determined by a set of non-linear equations similar to Einstein's equations. In this framework, we… (More)

- M. D. Maia
- 2008

Quaternion quantum mechanics is examined at the level of unbroken SU (2) gauge symmetry. A general quaternionic phase expression is derived from formal properties of the quaternion algebra. Quantum mechanics defined over general algebras have been conjectured since 1934 [1]. In 1936 Birkoff and von Neumann noted that the proposi-tional calculus implies in a… (More)

- M. D. Maia, Nildsen Silva
- 2008

The Arnowitt-Deser-Misner canonical formulation of general relativity is extended to the covariant brane-world theory in arbitrary dimensions. The exclusive probing of the extra dimensions makes a substantial difference, allowing for the construction of a non-constrained canonical theory. The quantum states of the brane-world geometry are defined by the… (More)

- M. D. Maia
- 2008

The cosmological constant problem is examined under the assumption that the extrinsic curvature of the space-time contributes to the vacuum. A compensation mechanism based on a variable cosmological term is proposed. Under a suitable hypothesis on the behavior of the extrinsic curvature, we find that an initially large Λ(t) rolls down rapidly to zero during… (More)

- M D Maia
- 2007

It is shown that a space-time hypersurface of a 5-dimensional Ricci at space-time has its energy-momentum tensor algebraically related to its extrinsic curvature. Since an electromagnetic-like eld does not arise naturally from this geometry, a Kaluza-Klein model based on 5-dimensional Ricci-at embedding spaces would require further assumptions.

- M. D. Maia
- 2008

The compatibility between general relativity and the property that space-times are ebeddable manifolds is further examined. It is shown that the signature of the embedding space is uniquely determined provided the embedding space is real and its dimension is kept to the minimal. Signature changes produce complex embeddings which in turn may induce… (More)

- M D Maia
- 2008

The cosmological constant problem is seen as a symptom of the ambiguity of the Riemann curvature in general relativity. The solution of that ambiguity provided by Nash's theorem on gravitational perturbations along extra dimensions eliminate the direct comparison between the vacuum energy density and Einstein's cosmological constant, besides being… (More)

- P. Chambel-Leitão, F. Braunschweig, L. Fernandes, R. Neves, P. Galvão, Manuel da Maia
- 2007

MOHID Water Modelling System is an integrated state of the art modular system, composed by a series of models that simulate surface water bodies, streams and watersheds. MOHID's code development follows a methodology which improves its robustness related to programming errors. MOHID is written in ANSI FORTRAN 95, profiting from all its new features,… (More)

- M. D. Maia
- 1998

A dynamical theory of hypersurface deformations is presented. It is shown that a (n+1)-dimensional space-time can be always foliated by pure deformations , governed by a non zero Hamiltonian. Quantum deformation states are defined by Schrödinger's equation constructed with the corresponding deformation Hamiltonian operator, interpreted as the generator of… (More)

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