Generation of Closed Timelike Curves with Rotating Superconductors

The spacetime metric around a rotating SuperConductive Ring (SCR) is deduced from the gravitomagnetic London moment in rotating superconductors. It is shown that theoretically it is possible to generate Closed Timelike Curves (CTC) with rotating SCRs. The possibility to use these CTC's to travel in time as initially idealized by G\"{o}del is investigated. It is shown however, that from a technology and experimental point of view these ideas are impossible to implement in the present context.Comment: 9 pages. Submitted to Classical and Quantum Gravit

Efeito do armazenamento na qualidade de sementes de linhagens de sorgo.

bitstream/item/46073/1/circ-163.pd

Análises de tecido vegetal: manual de laboratório.

bitstream/item/57831/1/CPATU-Doc92.pd

Quintessence and Scalar Dark Matter in the Universe

Continuing with previous works, we present a cosmological model in which dark matter and dark energy are modeled by scalar fields $\Phi$ and $\Psi$, respectively, endowed with the scalar potentials $V(\Phi)=V_{o}[ \cosh {(\lambda \sqrt{\kappa_{o}}\Phi)}-1]$ and $\tilde{V}(\Psi)=\tilde{V_{o}}[ \sinh {(\alpha \sqrt{\kappa_{o}}\Psi)}] ^{\beta}$. This model contains 95% of scalar field. We obtain that the scalar dark matter mass is $m_{\Phi}\sim 10^{-26}eV.$ The solution obtained allows us to recover the success of the standard CDM. The implications on the formation of structure are reviewed. We obtain that the minimal cutoff radio for this model is $r_{c}\sim 1.2 kpc.$Comment: 4 pages REVTeX, 3 eps color figures. Minor changes and references updated. To appear in Classical and Quantum Gravity as a Letter to the Editor. More information at http://www.fis.cinvestav.mx/~siddh/PHI

Métodos de superação de dormência em Piptadenia adiantoides (SPRENG.) J.F. MACBR. (Fabaceae:Mimosoideae).

O objetivo deste trabalho foi avaliar os tratamentos mais eficazes na promoção da germinação de sementes de P. adiantoides, propor sua utilização como alternativa para o reflorestamento e proporcior novas informações sobre a espécie Piptadenia adiantoides

Distribution of Handroanthus heptaphyllus in Brazil and future projections according to global climate change.

In this work, we mapped the distribution of Handroanthus heptaphyllus in Brazil and projected future scenarios of climate change, using potential distribution modeling (MDP). In the first step, we mapped the climate of the current period and for future scenarios (1961-1990, 2011-2041, 2041-2070 and 2071-2100, respectively). the next step, these maps were compared to the 114 points of occurrences of the species. The climate projections were made in accordance with scenarios presented in the 4th Assessment Report of the Intergovernmental Panel on Climate Change - AR4 / IPCC. The projections for the next decades indicate alterations in the distribution of H. heptaphyllus. Additionally, it demonstrated a significant reduction of distribution areas in the northern limit, with retreated ecological niche from latitudes south and to higher altitudes. We conclude that the preservation of H. heptaphyllus, protecting it from the climatic changes that will occur in the next decades. The BAGs with the populations this species should be established based on the same criteria for the seed collection areas, in order to maintain the similar environmental conditions and avoid the effects of undue external influences

On the Hydrogen Atom via Wigner-Heisenberg Algebra

We extend the usual Kustaanheimo-Stiefel $4D\to 3D$ mapping to study and discuss a constrained super-Wigner oscillator in four dimensions. We show that the physical hydrogen atom is the system that emerges in the bosonic sector of the mapped super 3D system.Comment: 14 pages, no figure. This work was initiated in collaboration with Jambunatha Jayaraman (In memory), whose advises and encouragement were fundamental. http://www.cbpf.b