A nonsingular cosmological scenario is presented in which the currently observed Riemannian configuration of spacetime originates from a primordial Weylian “stiff matter” phase driven by a geometrized inflaton-like field. In the particular case of a Friedman-Robertson-Walker line element, it is shown that an unstable original Minkowski vacuum starts to collapse adiabatically at a remote past and bounces when a minimum radius is attained. Throughout the collapsing stage, this matter-free Universe is accelerated (or “inflationary”). As in models of spontaneous quantum creation, the bouncing phase can be shown to correspond to the propagation of a Weyl instanton in an Euclideanized, classically forbidden region. In the course of the bouncing period, concurrent to the maximal deviation of the Riemannian configuration, a geometry-driven amplification mechanism operates causing the exponential increase of entropy and matter fluctuations. Once the environment temperature is always bounded, this nonadiabatical process stands for a “ Big — but finite — Bang” creation event, followed by a standard radiation-dominated era. The model describes an eternal, Friedman-like open Universe, free of many problems that hinder standard cosmology; the observed existence of a baryon excess also fits naturally within the proposed scheme.

A Friedman-like scenario is described in which due to the direct coupling of electromagnetic fields to spacetime curvature-the total number of photons comprised in the Universe at a given epoch changes as the Universe expands. The photon number distribution function, according to this scenario, acquires an explicit dependence on a non-vanishing chemical potential term which accounts for the occurrence of tidal effects in the interaction of photons (which, in a gravitational field, should not be treated as idealised, point-like objects) with gravity. The total amount of entropy observed today may be reviewed from a new perspective and ipso facto explained away.

A comprehensive approach is suggested for describing the origin and evolution of large-scale magnetic fields. Vorticity-dependent fluctuations acting on a primordial charged plasma account for field generation, and the properties of gauge-invariant (but conformally non-invariant) couplings of electromagnetic and gravitational fields in a FRW background are applied in order to supply a source-independent, gravity-driven mechanism of conductance induction in the course of the reheating phase of inflationary cosmic scenarios. In consequence, the description of the behaviour of large-scale primordial magnetic fields is complemented so as to cover the whole post-inflationary history of the universe.

Genipap (Genipa americana-Rubiaceae) is native to tropical America, occurring in Brazil in practically all biomes, except in the Pampas. It has socioeconomic importance, mainly due to the use of fruits in the manufacture of sweets and juices besides the medicinal properties of its leaves. We evaluated the genetic diversity of 73 individuals from 15 natural populations in the state of Sergipe using ISSR markers. The choice of areas was made randomly and genetic material was extracted from young leaves. PCR analysis using nine markers generated 113 fragments, which were used to estimate genetic diversity. The Shannon index was 0.36 and the similarity of individuals varied between 0.11 and 0.81. The individuals Salgado 3 (SAL3) and Salgado 4 (SAL4) were the most similar (0.81) and seven pairs had low similarity (0.11). The genetic distance the UPGMA analysis, which divided individuals into two distinct groups. The level of genetic variability found allows differentiation between genotypes that can be used to enrich the Genipap Active GermPlasm Bank in Sergipe, and the information generated will be useful for the conservation of these genetic resources and in future breeding programs for this species.

We present a study of the nonminimal coupling of a vector field to gravity in the context of a Weyl integrable space-time (WIST). This system admits a cosmic solution in which such vector field is not determined dynamically although it rules the evolution of the metric. In a sense, the physical causes of the evolution of the cosmos appear to be out of dynamical control—a feature that can be assigned to a Marionette Universe.

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RESUMO:Humpty Dumpty é um personagem de "Alice no País do Espelho", de Lewis Carroll. Seu comportamento rebelde em relação ao significado das palavras é o ponto de partida para se problematizar os limites semânticos impostos aos leitores e aos falantes-ouvintes de uma língua natural. Dois livros de Umberto Eco sobre essa questão servem de base para se mostrar quais são esses limites. PALAVRAS-CHAVE:Interpretação, Leitor, Significado Literal. ABSTRACT:Humpty Dumpty is a character in "Alice through the Looking Glass", by Lewis Carroll. His rebel-like behavior in relation to the meaning of words is the starting point of the problematization of the semantic limits of readers and speakerhearers of a natural language. Two books by Umberto Eco on this matter serve as a basis for the showing what those limits are.