1,412 research outputs found
Bandgap properties of two-dimensional low-index photonic crystals
We study the bandgap properties of two-dimensional photonic crystals created
by a lattice of rods or holes conformed in a symmetric or asymmetric triangular
structure. Using the plane-wave analysis, we calculate a minimum value of the
refractive index contrast for opening both partial and full two-dimensional
spectral gaps for both TM and TE polarized waves. We also analyze the effect of
ellipticity of rods and holes and their orientation on the threshold value and
the relative size of the bandgap.Comment: 5 pages, 6 figures, App. Phys. B. styl
Magnetic Fluctuations in a Charge Ordered State of the One-Dimensional Extended Hubbard Model with a Half-Filled Band
Magnetic properties in a charge ordered state are examined for the extended
Hubbard model at half-filling. Magnetic excitations, magnetic susceptibilities
and a nuclear spin relaxation rate are calculated with taking account of
fluctuations around the mean-field solution. The relevance of the present
results to the observation in the 1:1 organic conductors, (TTM-TTP)I, is
discussed.Comment: 4 pages, 3 figures, to be published in J. Phys. Soc. Jpn. Vol.71
(2002) No.
Circular DNA Intermediate in the Duplication of Nile Tilapia vasa Genes
vasa is a highly conserved RNA helicase involved in animal germ cell development. Among vertebrate species, it is typically present as a single copy per genome. Here we report the isolation and sequencing of BAC clones for Nile tilapia vasa genes. Contrary to a previous report that Nile tilapia have a single copy of the vasa gene, we find evidence for at least three vasa gene loci. The vasa gene locus was duplicated from the original site and integrated into two distant novel sites. For one of these insertions we find evidence that the duplication was mediated by a circular DNA intermediate. This mechanism of gene duplication may explain the origin of isolated gene duplicates during the evolution of fish genomes. These data provide a foundation for studying the role of multiple vasa genes in the development of tilapia gonads, and will contribute to investigations of the molecular mechanisms of sex determination and evolution in cichlid fishes
Efeito de doses e queima de resĂduos orgânicos sobre a biomassa microbiana do solo.
O carbono da biomassa microbiana Ă© um indicador sensĂvel Ă s mudanças ocorridas no solo. Este trabalho teve o objetivo de avaliar o efeito da queima de resĂduos orgânicos sobre o conteĂşdo de carbono da biomassa microbiana do solo (C-bio) cultivado com milho adubado e sem adubação quĂmica..
Neutralização da acidez ativa e potencial dos solos mediante incubação com carbonato de cálcio.
- …