Low Mass Pseudoscalar Dark Matter in an Extended B - L Model

We study an extended B-L model, which has in its structure four neutral scalars. In this model, a representative set of parameters enable us to conclude that one of these scalars is a promising candidate for low-mass dark matter. We introduce an Z_2 symmetry, which ensure the stability of the dark matter. The dominant annihilation process will be through $s$-channel exchange of a scalar in $b\overline{b}$. So, this is also a Higgs portal dark matter model, but the Higgs decay to dark matter is suppressed and meets the constraints from invisible decays of Higgs boson. The model is also in agreement with the constraints established by XENON100, CoGeNT and CDMS experiments, maching the relic abundance and the cross section with nucleon.Comment: Version submitted and accepted for publication in PR

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

Avaliação de métodos de enxertia para a gravioleira em Viçosa-MG.

Visando obter informações sobre técnicas de enxertia em gravioleira (Annoma muricata L.), foram avaliados, neste trabalho, nove métodos de enxertia: garfagem à inglesa simples com e sem parafina; garfagem à inglesa com entalhe com e sem parafina; garfagem no topo em fenda cheia com e sem parafina; borbulhia em placa; borbulhia em janela aberta e borbulhia em T invertido. Os métodos de garfagem à inglesa simples e de garfagem no topo em fenda cheia, ambos com e sem parafinados, apresentaram maiores índices no pegamento e brotamento do enxerto. Apesar de não diferirem entre si, os métodos com uso de grafos parafinados podem ser recomendados por proporcionarem menor custo na produção de mudas enxertadas de graviola.Edição do XI Congresso Brasileiro de Fruticultura