Domain wall description of superconductivity

In the present work we shall address the issue of electrical conductivity in superconductors in the perspective of superconducting domain wall solutions in the realm of field theory. We take our set up made out of a dynamical complex scalar field coupled to gauge field to be responsible for superconductivity and an extra scalar real field that plays the role of superconducting domain walls. The temperature of the system is interpreted through the fact that the soliton following accelerating orbits is a Rindler observer experiencing a thermal bath.Comment: 9 pages, 5 figures, Latex. Version to appear in PL

Exciton trapping in magnetic wire structures

The lateral magnetic confinement of quasi two-dimensional excitons into wire like structures is studied. Spin effects are take into account and two different magnetic field profiles are considered, which experimentally can be created by the deposition of a ferromagnetic stripe on a semiconductor quantum well with magnetization parallel or perpendicular to the grown direction of the well. We find that it is possible to confine excitons into one-dimensional (1D) traps. We show that the dependence of the confinement energy on the exciton wave vector, which is related to its free direction of motion along the wire direction, is very small. Through the application of a background magnetic field it is possible to move the position of the trapping region towards the edge of the ferromagnetic stripe or even underneath the stripe. The exact position of this 1D exciton channel depends on the strength of the background magnetic field and on the magnetic polarisation direction of the ferromagnetic film.Comment: 10 pages, 7 figures, to be published in J. Phys: Condens. Matte

Menos insumos, mais qualidade.

Estudo mostra que a produção integrada de maçã requer menos insumos e mais mão-de-obra para o monitoramento. Como resultado, maior rentabilidade e menos custos de pós-colheita.Possui tabela comparativa de custo anual de produção de macieiras cvs Gala e Fuji nos sistemas de Produção Integrada e produção convencional (mar. 2001)

Detection of ionized gas in the globular cluster 47 Tucanae

We report the detection of ionized intracluster gas in the globular cluster 47 Tucanae. Pulsars in this cluster with a negative period derivative, which must lie in the distant half of the cluster, have significantly higher measured integrated electron column densities than the pulsars with a positive period derivative. We derive the plasma density within the central few pc of the cluster using two different methods which yield consistent values. Our best estimate of n_e = (0.067+-0.015)/cm^3 is about 100 times the free electron density of the ISM in the vicinity of 47 Tucanae, and the ionized gas is probably the dominant component of the intracluster medium.Comment: 5 pages, 3 included figures, accepted for publication by ApJ Letter

A new model to determine the dispersion of fatigue damage evaluations

Reliable predictions of remaining lives of civil or mechanical structures subjected to fatigue damage are very difficult to be made. In general, fatigue damage is extremely sensitive to the random variations of material mechanical properties, environment and loading. These variations may induce large dispersions when the structural fatigue life has to be predicted. Wirsching (1970) mentions dispersions of the order of 30 to 70 % of the mean calculated life. The presented paper introduces a model to estimate the fatigue damage dispersion based on known statistical distributions of the fatigue parameters (material properties and loading). The model is developed by expanding into Taylor series the set of equations that describe fatigue damage for crack initiation

Caracterização de genótipos de feijão-caupi [Vigna unguiculata (L.) WALP.] quanto à precocidade e à arquitetura.

Com o objetivo de verificar a existência de variabilidade genética e identificar genótipos de feijão-caupi de ciclo precoce, porte ereto, com hábito de crescimento determinado e produtivos, realizou-se um experimento no delineamento experimental de blocos casualizados, com 22 tratamentos e quatro repetições. Foram avaliados os caracteres floração inicial, maturidade, comprimento do hipocótilo, comprimento do epicótilo, comprimento do ramo principal, número de nós no ramo principal, número de ramos laterais, número de nós dos ramos laterais, ângulo de inserção do primeiro ramo lateral, ponto de colheita, acamamento e produtividade de grãos (Kg.ha-1). Os efeitos de tratamentos foram significativos para a maioria dos caracteres avaliados, com exceção do comprimento do hipocótilo e ângulo de inserção do primeiro ramo lateral. Os genótipos mais precoces foram, respectivamente: IT82D-889, AU94-MOB-816, IT82D-60, IT82E-49, IT82G-9 e MNCOO-544-14-1-2. Os genótipos com melhor arquitetura da planta foram, respectivamente: IT82G-9, IT82D-889 e AU-94-MOB-816. A maior produtividade de grãos foi expressa pelo genótipo TVX5058-09C-02, com 2.029,84 kg.ha-1, seguido pelos genótipos TE97-418-07-1 (1.587,9 kg.ha-1), UCR-95-701 (1.576,5 kg.ha-1), MNCOO544D-10-1-2-2 (1.548,6 kg.ha-1) e IT93K-93-10 (1.509,3 kg.ha-1), embora, não tenha diferença significativa entre esses genótipos pelo teste de Scott Knott

Cultivares do algodoeiro para o cerrado.

bitstream/CNPA/18295/1/CIRTEC93.pd

Primeiro registro de Bipolaris bicolor em plantas de açaizeiro.

AG-051

BRS Aroeira - Nova cultivar de algodoeiro para Mato Grosso do Sul.

bitstream/item/24861/1/COT200255.pdfDocumento on-line