An unified cosmological evolution driven by a mass dimension one fermionic field

An unified cosmological model for an Universe filled with a mass dimension one (MDO) fermionic field plus the standard matter fields is considered. After a primordial quantum fluctuation the field slowly rolls down to the bottom of a symmetry breaking potential, driving the Universe to an inflationary regime that increases the scale factor for about 71 e-folds. After the end of inflation, the field starts to oscillate and can transfer its energy to the standard model particles through a reheating mechanism. Such a process is briefly discussed in terms of the admissible couplings of the MDO field with the electromagnetic and Higgs fields. We show that even if the field loses all its kinetic energy during reheating, it can evolve as dark matter due a gravitational coupling (of spinorial origin) with baryonic matter. Since the field acquires a constant value at the bottom of the potential, a non-null, although tiny, mass term acts as a dark energy component nowadays. Therefore, we conclude that MDO fermionic field is a good candidate to drive the whole evolution of the Universe, in such a way that the inflationary field, dark matter and dark energy are described by different manifestations of a single field.Comment: 22 pages, 5 figure

Generalized q-deformed Correlation Functions as Spectral Functions of Hyperbolic Geometry

We analyse the role of vertex operator algebra and 2d amplitudes from the point of view of the representation theory of infinite dimensional Lie algebras, MacMahon and Ruelle functions. A p-dimensional MacMahon function is the generating function of p-dimensional partitions of integers. These functions can be represented as amplitudes of a two-dimensional c=1 CFT. In this paper we show that p-dimensional MacMahon functions can be rewritten in terms of Ruelle spectral functions, whose spectrum is encoded in the Patterson-Selberg function of three dimensional hyperbolic geometry.Comment: 12 pages, no figure

Euclidean thermal spinor Green's function in the spacetime of a straight cosmic string

Within the framework of the quantum field theory at finite temperature on a conical space, we determine the Euclidean thermal spinor Green's function for a massless spinor field. We then calculate the thermal average of the energy-momentum tensor of a thermal bath of massless fermions. In the high-temperature limit, we find that the straight cosmic string does not perturb the thermal bathComment: 11 pages, latex, no figure

Operator Product on Locally Symmetric Spaces of Rank One and the Multiplicative Anomaly

The global multiplicative properties of Laplace type operators acting on irreducible rank one symmetric spaces are considered. The explicit form of the multiplicative anomaly is derived and its corresponding value is calculated exactly, for important classes of locally symmetric spaces and different dimensions.Comment: Int. Journal of Modern Physics A, vol. 18 (2003), 2179-218

Massive scalar field near a cosmic string

The $\zeta$ function of a massive scalar field near a cosmic string is computed and then employed to find the vacuum fluctuation of the field. The vacuum expectation value of the energy-momentum tensor is also computed using a point-splitting approach. The obtained results could be useful also for the case of self-interacting scalar fields and for the finite-temperature Rindler space theory.Comment: 15 pages, standard LaTeX, no figures. Reference [14] correcte

Cosmic String Wakes in Scalar-Tensor Gravities

The formation and evolution of cosmic string wakes in the framework of a scalar-tensor gravity are investigated in this work. We consider a simple model in which cold dark matter flows past an ordinary string and we treat this motion in the Zel'dovich approximation. We make a comaprison between our results and previous results obtained in the context of General Relativity. We propose a mechanism in which the contribution of the scalar field to the evolution of the wakes may lead to a cosmological observation.Comment: Replaced version to be published in the Classical and Quantum Gravit

International partnership for rice improvement in Latin America: CIRAD, a case study.

In Latin America and the Caribbean (LAC), rice is an important staple food. A significant increase in rice production has bean achieved mainly through the release and adoption of high yielding varieties. during the last 40 years, about 300 varieties were released. They were developed by national and international rice research institutions. The Centre for International Cooperation in Agricultural Research for Development, Food Crop Department (CIRAD-CA), in Montpellier, France, worked in collarotation with Embrapa Rice and Beans, Goiânia, Brazil, and the International Centre for Tropical Agriculture (CIAT), Cali, Colombia, in the development of varieties for LAC. This study looks at the contribution made by CIRAD's international partnership to rice improvement, with emphasis in Latin America. The presence of CIRAD's lines was detected in the breeding programs in Brazil, Bolivia, Colombia, Mexico, Guatemala and Peru. The following results were obtained: a) 61 unique lines developed by CIRAD were used as parents in mote than 2,000 crosses in the region; b) five CIRAD's lines were directly released as commercial cultivars; c) 25 varieties released to farmers in the region have at least one line from CIRAD participating on its crosses; and d) six breeding lines are in the pipeline for release in Brazil, Colombia, Nicaragua and Peru

Um método para a determinação automática de áreas de preservação permanente em topos de morros para o Estado de São Paulo.

Através da utilização de ferramentas de geoprocessamento, este trabalho propõe o exemplo de um método desenvolvido para delimitação do terço superior dos topos de morro e linhas de cumeada para o Estado de São Paulo, compatível com a escala de 1:250.000, no limite da mesma. Para desenvolvimento e tese desse método, optou-se pelo Estado de São Paulo em função de sua extensão. Tendo o seu relevo representado por "mar de morros", serras como a Serra do Mar e relevos levemente ondulados em sua porção oeste, a área de estudo permite uma boa confrontação com informações georreferenciadas disponíveis em diversos órgãos e instituições de pesquisa, bem como na iniciativa privada