Tunable Double Negative Band Structure from Non-Magnetic Coated Rods

A system of periodic poly-disperse coated nano-rods is considered. Both the coated nano-rods and host material are non-magnetic. The exterior nano-coating has a frequency dependent dielectric constant and the rod has a high dielectric constant. A negative effective magnetic permeability is generated near the Mie resonances of the rods while the coating generates a negative permittivity through a field resonance controlled by the plasma frequency of the coating and the geometry of the crystal. The explicit band structure for the system is calculated in the sub-wavelength limit. Tunable pass bands exhibiting negative group velocity are generated and correspond to simultaneously negative effective dielectric permittivity and magnetic permeability. These can be explicitly controlled by adjusting the distance between rods, the coating thickness, and rod diameters

Finite element mesh generator: GMALHA

The mesh generator GMALHA was developed for the construction of non-structured triangular meshes used in sea wave propagation finite element models. For a given coastal zone delimited by a boundary line and characterised by its bathymetry, GMALHA generates an optimal triangular mesh. The boundary, which sometimes can be very complex, includes a coastline with port infrastructures, beaches, marinas, islands, etc. . . Based on that boundary and bathymetric information within it, GMALHA, first generates a rough triangular mesh that fills the domain. The mesh is then subjected to post-processing, such as: local refinement and optimization (control of elements uniformity, repositioning of points to correct angles and edge swaps to correct node valence). This paper describes the generation, refinement and optimization algorithms of GMALHA. The advantages of this generator are also illustrated with some practical cases of sea wave propagation in coastal areas.Peer Reviewe

Schizophrenic active neutrinos and exotic sterile neutrinos

We implement a schizophrenic scenario for the active neutrinos in a model in which there are also exotic right-handed neutrinos making a model with a local U(1)_(B-L) anomaly free. Two of right-handed neutrinos carry B-L=-4 while the third one carries B-L=5.Comment: I, A. C. B. Machado, apologize for having submitted the wrong file before. This is in fact the version to be published in Physics Letters B 698 (2011) pp. 128-13

Oxide thermoelectrics prepared by laser melting: effects of processing atmosphere

Traditional thermoelectric materials suffer from two main problems, the toxicity/scarcity of the elements used and their stability at high temperatures or in non-inert atmospheres. Thermoelectric oxides appear to be a promising alternative to traditional materials due to natural abundance of the constituents and high thermal stability. This work focuses on the processing of these materials using the Laser Floating Zone (LFZ) technique. Particular emphasis is given to LFZ processing under various redox atmospheres, allowing unique opportunities for tuning the structural, microstructural and thermoelectric properties. This technique allows the growth of fully dense fibres, as well as the formation of metastable phases and/or promoting different oxidation states by adjusting the growth conditions. Here we report the processing of model manganite- and titanate-based materials including donorsubstituted Ca(Pr)MnO3 and Ti(Ta)O2 systems. XRD/SEM/EDS studies demonstrate some guidelines for tuning the phase composition and microstructure by adjusting the growth rate under different redox conditions. We report high power factor values of 303 μWm-1K -2 at 1120 K for the Ca(Pr)MnO3 system and 317 μWm-1K -2 for the Ti(Ta)O2 system. The obtained results suggest that LFZ is a suitable technique for processing thermoelectric oxides if optimized control over growth parameters and re-equilibration conditions is imposed.publishe

Diagnóstico das pisciculturas do Programa Peixe Vida em Mato Grosso do Sul.

Características das pisciculturas; Manejo da Piscicultura; Espécies cultivadas; Manjo sanitário; Avaliaçõa da atividade pelos piscicultores.bitstream/item/38092/1/DOC200569.pd