Topological defects in lattice models and affine Temperley-Lieb algebra

This paper is the first in a series where we attempt to define defects in critical lattice models that give rise to conformal field theory topological defects in the continuum limit. We focus mostly on models based on the Temperley-Lieb algebra, with future applications to restricted solid-on-solid (also called anyonic chains) models, as well as non-unitary models like percolation or self-avoiding walks. Our approach is essentially algebraic and focusses on the defects from two points of view: the "crossed channel" where the defect is seen as an operator acting on the Hilbert space of the models, and the "direct channel" where it corresponds to a modification of the basic Hamiltonian with some sort of impurity. Algebraic characterizations and constructions are proposed in both points of view. In the crossed channel, this leads us to new results about the center of the affine Temperley-Lieb algebra; in particular we find there a special subalgebra with non-negative integer structure constants that are interpreted as fusion rules of defects. In the direct channel, meanwhile, this leads to the introduction of fusion products and fusion quotients, with interesting mathematical properties that allow to describe representations content of the lattice model with a defect, and to describe its spectrum.Comment: 41

Diversity of parasites in wild Astronotus ocellatus (Perciformes, Cichlidae), an ornamental and food fish in Brazil.

The community composition of parasites was characterized in Astronotus ocellatus from a tributary of the Amazon River, northern Brazil. The prevalence was 87.9%, and a total of 526,052 parasites were collected, with a mean of 15,941 parasites per host. Nine taxa of ecto- and endo-parasites were identified, but Ichthyophthirius multifiliis was the dominant species, while Piscinoodinium pillulare, Clinostomum marginatum and Argulus multicolor were the least prevalent parasites. The parasite community was characterized by a low species richness, low diversity and low evenness. Host body size was not found to influence the composition of the parasite community, and there was no significant correlation between abundance of any parasite species and host body size. Papers published concerning the presence of parasites in this host in different hydrographic basins within Brazil indicate that 22 species of parasites are known to infect A. ocellatus, including species of ectoparasites and endoparasites. In Brazil, ectoparasites species, particularly crustaceans, have been found to parasitize A. ocellatus in relatively high numbers. This predominance of ectoparasites is typical of fish of lentic ecosystems. Finally, the presence of different endoparasites taxa suggest that A. ocellatus acts as an intermediate or definitive host

Influência de parâmetros ambientais sobre a comunidade de peixes de um afluente da margem esquerda do Rio Amazonas, Amazônia Oriental.

A distribuição de espécies sempre foi a preocupação central da ecologia. Este estudo visa compreender a relação de fatores abióticos que podem afetar a distribuição especial e sazonal da ictiofauna do rio Matapi um afluente da margem esquerda do rio Amazonas na região central do estado do Amapá, região da Amazônia Oriental, em um percurso de aproximadamente 90 km de extensão. Os peixes foram coletados bimensalmente durante um ciclo anual, utilizando rede de emalhar de diferentes tamanhos, matapis, tarrafas, linhas de mão e espinhel de fundo, em um raio de 1000 metros. Também o pH, condutividade elétrica, sólidos suspensos, transparência e outros fatores secundários como profundidade e largura do rio foram mensurados. Análise de variância com dois fatores (ANOVA- Two-way) foi usada para testar as diferenças espaciais e temporais para os fatores abióticos analisados. Foram identificadas 105 espécies, mas apenas as espécies com frequência a partir de 0,5% fizeram parte da analise, de forma que somente 29 espécies foram usadas. As matrizes foram submetidas à analise multivariada de ordenação (Co-inércia) para encontrar padrões na estrutura da ictiofauna relacionados aos diferentes fatores abióticos investigados. Os resultados indicaram parâmetros ambientais não mostraram diferenças sazonais, mas sim entre áreas de coleta. Já a ictiofauna mostrou diferenças tanto sazonal como espacial. Análise de co-inércia sumarizou eficientemente que a estrutura da ictiofauna e dos fatores ambientais ocorreram espacialmente, independentemente da sazonalidade e que os fatores determinantes dessa distribuição foram a transparência, condutividade, largura do rio e sólidos suspensos.Esses estudos podem contribuir para orientar a gestão ambiental e esforços de conservação ao longo desse importante tributário do rio Amazonas.CB19

A New species of Tripartiella (Ciliophora: Trichodinidae) from Aequidens tetramerus (Perciformes: Cichlidae) in north Brazil.

A new species of Tripartiella is described from the gills of the wild saddle cichlid Aequidens tetramerus in north Brazil. Wet smears of skin and gills of examined fish were air-dried at room temperature and impregnated with Klein?s dry silver method for examination of the adhesive disc?s structures and denticles. Total prevalence of parasitism was 65%. This ciliate is characterized as a small-sized trichodinid, body diameter 37.03 ± 4.9 μm, adhesive disc 30.50 ± 2.71 μm, denticulate ring 13.28 ± 0.8 μm and 24 ± 2.0 denticles. Taxonomic and morphometric data for the new species are discussed

Seleção de plantas matrizes de maracujazeiro em Sergipe.

bitstream/item/87938/1/CPATC-PESQ.-AND.-21-97.pd

Parasitos das brânquias de 16 espécies de Cichlidae da Bacia do Igarapé Fortaleza, Macapá, Estado do Amapá, Brasil.

ENBRAPOA

Parasitos de Oreochromis niloticus, Cichlidae invasor da Bacia do Igarapé Fortaleza, região do estuário amazônico do Estado do Amapá.

ENBRAPOA