5,491 research outputs found
Modulated phases and devil's staircases in a layered mean-field version of the ANNNI model
We investigate the phase diagram of a spin- Ising model on a cubic
lattice, with competing interactions between nearest and next-nearest neighbors
along an axial direction, and fully connected spins on the sites of each
perpendicular layer. The problem is formulated in terms of a set of
noninteracting Ising chains in a position-dependent field. At low temperatures,
as in the standard mean-feild version of the Axial-Next-Nearest-Neighbor Ising
(ANNNI) model, there are many distinct spatially commensurate phases that
spring from a multiphase point of infinitely degenerate ground states. As
temperature increases, we confirm the existence of a branching mechanism
associated with the onset of higher-order commensurate phases. We check that
the ferromagnetic phase undergoes a first-order transition to the modulated
phases. Depending on a parameter of competition, the wave number of the striped
patterns locks in rational values, giving rise to a devil's staircase. We
numerically calculate the Hausdorff dimension associated with these
fractal structures, and show that increases with temperature but seems
to reach a limiting value smaller than .Comment: 17 pages, 6 figure
Aplicação da geoestatística em observações de campo realizadas pelo produtor sobre o desenvolvimento de videiras.
Complete Genome Sequence of Xanthomonas arboricola pv. juglandis 417, a Copper-Resistant Strain Isolated from Juglans regia L.
Here, we report the complete genome sequence of Xanthomonas arboricola pv. juglandis 417, a copper-resistant strain isolated from a blighted walnut fruit (Juglans regia L. cv. Chandler). The genome consists of a single chromosome (5,218 kb)
On the effective action of the vacuum photon splitting in Lorentz-violating QED
We consider one-loop radiative corrections from Lorentz- and CPT- violating
extended QED to address the specific problem of finding explicitly an effective
action describing amplitude of photon triple splitting. We show that it is not
possible to find a nonzero photon triple splitting effective action, at least
by using the derivative expansion method (at zero external momenta), up to
leading order in the Lorentz- and CPT- violating parameter.Comment: 4 pages, version to appear in EP
Portais Web desenvolvidos no laboratório de bioinformática da Embrapa Soja.
bitstream/item/71973/1/ID-30955.pd
Divergência genética entre genótipos de aceroleira da Embrapa Semiárido.
O presente trabalho teve como objetivo a análise da divergência genética em um grupo de genótipos de aceroleira do programa de melhoramento genético da Embrapa Semiárido
Divergência fenotípica em acessos de aceroleira da Embrapa Semiárido.
O presente trabalho objetivou analisar a divergência entre 35 acessos do Banco de Germoplasma de aceroleira da Embrapa Semiárido, em Petrolina, PE
Physiological seed quality of 'BRS Mari' hot pepper during seed development and maturation.
Abstract 78
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