Lorentz-violating nonminimal coupling contributions in mesonic hydrogen atoms and generation of photon higher-order derivative terms

We have studied the contributions of Lorentz-violating CPT-odd and CPT-even nonminimal couplings to the energy spectrum of the mesonic hydrogen and the higher-order radiative corrections to the effective action of the photon sector of a Lorentz-violating version of the scalar electrodynamics. By considering the complex scalar field describes charged mesons (pion or kaon), the non-relativistic limit of the model allows to attain upper-bounds by analyzing its contribution to the mesonic hydrogen energy. By using the experimental data for the $1S$ strong correction shift and the pure QED transitions $4P \rightarrow 3P$, the best upper-bound for the CPT-odd coupling is $<10^{-12}\text{eV}^{-1}$ and for the CPT-even one is $<10^{-16}\text{eV}^{-2}$. Besides, the CPT-odd radiative correction to the photon action is a dimension-5 operator which looks like a higher-order Carroll-Field-Jackiw term. The CPT-even radiative contribution to the photon effective action is a dimension-6 operator which would be a higher-order derivative version of the minimal CPT-even term of the standard model extension

Coupling vortex dynamics with collective excitations in Bose-Einstein Condensates

Here we analyze the collective excitations as well as the expansion of a trapped Bose-Einstein condensate with a vortex line at its center. To this end, we propose a variational method where the variational parameters have to be carefully chosen in order to produce reliable results. Our variational calculations agree with numerical simulations of the Gross-Pitaevskii equation. The system considered here turns out to exhibit four collective modes of which only three can be observed at a time depending of the trap anisotropy. We also demonstrate that these collective modes can be excited using well established experimental methods such as modulation of the s-wave scattering length

Gaussian quantum Monte Carlo methods for fermions

We introduce a new class of quantum Monte Carlo methods, based on a Gaussian quantum operator representation of fermionic states. The methods enable first-principles dynamical or equilibrium calculations in many-body Fermi systems, and, combined with the existing Gaussian representation for bosons, provide a unified method of simulating Bose-Fermi systems. As an application, we calculate finite-temperature properties of the two dimensional Hubbard model.Comment: 4 pages, 3 figures, Revised version has expanded discussion, simplified mathematical presentation, and application to 2D Hubbard mode

Levantamento da podridão do estipe da pupunha no litoral do Paraná.

Organizado por Patricia Póvoa de Mattos, Celso Garcia Auer, Rejane Stumpf Sberze, Katia Regina Pichelli e Paulo César Botosso

Population dynamics of the root lesion nematode, Pratylenchus brachyurus, in soybean fields in Tocantins state and its effect to soybean yield.

Pratylenchus brachyurus has become increasingly common in soybean fields throughout Brazil where yield loss assessments have reported reduction up to 30%. Currently, no soybean cultivars resistant to P. brachyurus have been identified, and management strategies include crop rotation with non-host crops, fallow, and the application of nematicides. The goals of this study were to examine the population dynamics of P. brachyurus in soybean fields throughout Tocantins state and in areas planted with off-season crops following soybean harvest in a crop succession scheme. Pratylenchus brachyurus was present in ca. 82% of samples with densities in soybean fields ranging from 23 to 20,400 nematodes per 200 cm3 soil or 10 g root samples. In two sites, the mean nematode density was higher within infestation foci, which were characterized by poor soybean growth, compared to those from outside infestation foci, with an overall reduction of 44.3% in plant height and 39.7% in pod numbers. Following soybean harvest in areas planted with off-season crops including maize, sorghum, millet, crotalaria as well as an area maintained as a fallow treatment, the mean density of P. brachyurus ranged from 122 to 504 individuals per 10 g root sample and from 3 to 96 per 200 cm3 soil. Overall, the mean density of nematodes did not differ significantly among plant species and all crops used in the succession scheme allowed P. brachyurus multiplication. In summary, off-season cultivation with the crops used in this study is not recommended for management of P. brachyurus in soybean, but the use of fallow or non-hosts may be helpful in lowering the population density of P. brachyurus in soybean fields

Experimental analysis of lateral impact on planar brittle material: spatial properties of the cracks

The breakup of glass and alumina plates due to planar impacts on one of their lateral sides is studied. Particular attention is given to investigating the spatial location of the cracks within the plates. Analysis based on a phenomenological model suggests that bifurcations along the cracks' paths are more likely to take place closer to the impact region than far away from it, i. e., the bifurcation probability seems to lower as the perpendicular distance from the impacted lateral in- creases. It is also found that many observables are not sensitive to the plate material used in this work, as long as the fragment multiplicities corresponding to the fragmentation of the plates are similar. This gives support to the universal properties of the fragmentation process reported in for- mer experiments. However, even under the just mentioned circumstances, some spatial observables are capable of distinguishing the material of which the plates are made and, therefore, it suggests that this universality should be carefully investigated

Seleção de isolados do fungo Hirsutella thompsonii (Fisher) para controle do ácaro-do-coqueiro Aceria guerreronis (Keiffer).

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