980 resultados para Sl 19


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We consider a two-dimensional integrable and conformally invariant field theory possessing two Dirac spinors and three scalar fields. The interaction couples bilinear terms in the spinors to exponentials of the scalars. Its integrability properties are based on the sl(2) affine Kac-Moody algebra, and it is a simple example of the so-called conformal affine Toda theories coupled to matter fields. We show, using bosonization techniques, that the classical equivalence between a U(1) Noether current and the topological current holds true at the quantum level, and then leads to a bag model like mechanism for the confinement of the spinor fields inside the solitons. By bosonizing the spinors we show that the theory decouples into a sine-Gordon model and free scalars. We construct the two-soliton solutions and show that their interactions lead to the same time delays as those for the sine-Gordon solitons. The model provides a good laboratory to test duality ideas in the context of the equivalence between the sine-Gordon and Thirring theories. © 2000 Elsevier Science B.V. All rights reserved.

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We consider an integrable conformally invariant two-dimensional model associated to the affine Kac-Moody algebra sl3(ℂ). It possesses four scalar fields and six Dirac spinors. The theory does not possesses a local Lagrangian since the spinor equations of motion present interaction terms which are bilinear in the spinors. There exists a submodel presenting an equivalence between a U(1) vector current and a topological current, which leads to a confinement of the spinors inside the solitons. We calculate the one-soliton and two-soliton solutions using a procedure which is a hybrid of the dressing and Hirota methods. The soliton masses and time delays due to the soliton interactions are also calculated. We give a computer program to calculate the soliton solutions. © 2002 Published by Elsevier Science B.V.

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The genetic variation in the growth of seven 19-year-old Liquidambar styraciflua provenances was studied in Paraguaçu Paulista, São Paulo State, Brazil. The trial was established in a complete randomized block design with seven provenances, four replications and twelve-tree square plots. Significant differences among provenances were detected for diameter at breast height, height and volume, indicating the possibility of increasing timber yield through selection of the most productive provenances. Genetic correlations between growth traits were high and statistically significant. The provenance from Finca las Victorias, Guatemala had the best and the provenance from Franklin, Virginia, United States the poorest performance for all traits. A growth comparison of Pinus caribaea var. bahamensis with the best provenance at the same site indicated that the potential of L. styraciflua for silviculture in the region of Paraguaçu Paulista is high.

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Objective: To evaluate if identified loci associated with normal age of menopause variation and early menopause can account for the poor response to controlled ovarian stimulation. Methods: A total of 71 patients, with age ≤ 35 years old, undergoing intracytoplasmic sperm injection were tested for three of the four newly identified genetic variants associated with normal variation in menopausal age and early menopause. Patients were divided into two groups: poor responder group (PR group, n=21) and normoresponder group (NR group, n=50). The influence of risk allele frequency on the response to controlled ovarian stimulation (COS) was evaluated. Logistic regression models were used. Results: There was no significant difference in the incidence of the genetic variants between NR and PR group. The risk allele for chromosome 19 variant (rs4806660) demonstrated a protective effect. The presence of a risk allele, either in homozygosis or in heterozygosis, was associated with an increased response to COS, resulting in an elevated number of follicles (Coef: 2.54, P= 0.041) and retrieved oocytes (Coef: 1.41, P= 0.041). Conclusions: Genetic variants rs244715, rs9379896 and rs4806660 are not risk factors for poor ovarian response. Instead, rs4806660 is associated with higher number of follicles and retrieved oocytes. It could be hypothesized that rs4806660 is associated with an increased response to gonadotrophin stimulus. © Todos os direitos reservados a SBRA - Sociedade Brasileira de Reprodução Assistida.