Superconducting charge qubits from a microscopic many-body perspective

The quantised Josephson junction equation that underpins the behaviour of charge qubits and other tunnel devices is usually derived through cannonical quantisation of the classical macroscopic Josephson relations. However, this approach may neglect effects due to the fact that the charge qubit consists of a superconducting island of finite size connected to a large superconductor. We show that the well known quantised Josephson equation can be derived directly and simply from a microscopic many-body Hamiltonian. By choosing the appropriate strong coupling limit we produce a highly simplified Hamiltonian that nevertheless allows us to go beyond the mean field limit and predict further finite-size terms in addition to the basic equation.Comment: Accepted for J Phys Condensed Matte

Produção e composição química de aveia não irrigada em quatro épocas de corte.

A aveia preta e os cultivadores UPF2, UPF3 e UPF7 de aveia amarela foram avaliados durante o período de inverno, sem irrigação em Jaboticabal-SP. As plantas foram colhidas aos 51, 64, 77 e 90 dias após a semeadura. A produção de MS variou de 931,6 a 2378,3 kg/ha para aveia preta, de 903,4 a 3135,2 kg/ha para a cv. UPF2 de 439,7 a 3920,9 kg/ha para a cv. UPF3 e de 1003,7 a 4351.1 kg/ha para a cv. UPF7. Dos 51 aos 90 dias após a semeadura os teores de PB na folha decresceram, de 18,0% para 10,2%, e os de FDN aumentaram de 41,6% para 47,9%.Resumo expandid

Generalization of Dirac Non-Linear Electrodynamics, and Spinning Charged Particles

In this note we generalized the Dirac non-linear electrodynamics, by introducing two potentials (namely, the vector potential A and the pseudo-vector potential gamma^5 B of the electromagnetic theory with charges and magnetic monopoles) and by imposing the pseudoscalar part of the product omega.omega* to be zero, with omega = A + gamma^5 B. We show that the field equations of such a theory possess a soliton-like solution which can represent a priori a "charged particle", since it is endowed with a Coulomb field plus the field of a magnetic dipole. The rest energy of the soliton is finite, and the angular momentum stored in its electromagnetic field can be identified --for suitable choices of the parameters-- with the spin of the charged particle. Thus this approach seems to yield a classical model for the charged (spinning) particle, which does not meet the problems met by earlier attempts in the same direction.Comment: standard LaTeX file; 16 pages; it is a corrected version of a paper appeared in Found. Phys. (issue in honour of A.O.Barut) 23 (1993) 46

Solid Freeform Fabrication of Functional Silicon Nitride Ceramics by Laminated Object Manufacturing 1

The processing of silicon nitride (Si3N4) structural ceramics by Laminated Object Manufacturing (LOM) using ceramic tape preforms was investigated. The key processing stages involved green shape formation (which used the LOM process), followed by the burnout of all organics, and final densification by pressureless sintering. Two material systems were considered. These were a) monolithic Si3N4 and b) a preceramic polymer infiltrated Si3N4. The raw materials for the process were tape preforms of Si3N4, which were fabricated by standard tape casting techniques. Mechanical property data obtained for the LOM processed Si3N4 showed high strength and fracture toughness values. The room temperature and high temperature (1260 o C) flexural strengths were in the range of 700-900 MPa and 360-400 MPa, respectively. The fracture toughness averaged from 5.5-7.5 MPa.m1/2. These strength and fracture toughness values are comparable to those reported for conventionally prepared Si3N4 ceramics. Thus, this research demonstrated that the LOM technique is a viable method for preparing functional Si3N4 ceramics with good physical and mechanical properties.Mechanical Engineerin

Evaluation of Oat Genotypes for Forage and Seed Production in the Northeast Region of Sao Paulo State-Brazil

The DM production (DMP), chemical composition, and seed production of black oats (Avena strigosa Schreb.) and the yellow oat cultivars ‘UPF2’ , ‘UPF3’ and ‘UPF7’ (A. byzantina C. Kock.) were evaluated under two management systems: plants cut (60 days after sowing-DAS) and uncut for seed production. Oat genotypes were sown in 1993 and 1994. UPF7 was the least productive. No difference was detected (P \u3e 0.05) in the cell wall composition of the genotypes. High values of CP (22.9%) and IVDMD (77.6%) were determined across all genotypes. In 1994, cutting at 60 DAS affected the seed production of the cultivars. All oat genotypes presented satisfactory forage and grain production in both management systems. Seed production can be reduced in all genotypes evaluated due to variations in climatic conditions and leaf rust disease

ANALYSIS OF CESAREAN SECTION RATES AND INDICATIONS USING TEN GROUP CLASSIFICATION

Introdução e objetivo: Foi efetuado um estudo observacional retrospetivo para analisar os motivos de cesariana e identificar os parâmetros obstétricos das mulheres a ela submetidas na nossa instituição em janeiro/fevereiro e junho/julho de 2011. Material e Métodos: Foram revistos os processos clínicos destas mulheres, categorizadas nos dez grupos obstétricos propostos por Robson, baseados nos seguintes parâmetros: gestação simples/múltipla; nuliparidade/multiparidade/multiparidade com cesariana anterior, cefálico/não-cefálico; parto espontâneo/ induzido/cesariana eletiva; parto de termo/pré-termo. Em cada grupo foram analisados os motivos de cesariana excepto os das gestações múltiplas. Resultados: Ocorreram 1167 partos simples, 391 por cesariana, sendo a taxa de cesarianas 33,5% (36% eletivas). A cesariana foi mais frequente em nulíparas de termo com parto induzido e em mulheres com cesariana prévia. Durante o trabalho de parto o motivo mais comum nomeado pelo clínico foi o trabalho de parto estacionário, a incompatibilidade feto-pélvica e o estado fetal não tranquilizador. A apresentação fetal anómala motivou 4,4% da taxa de cesarianas, contributo superior ao da prematuridade (3%). Entre as multíparas de termo sem cicatriz uterina houve menor número de cesarianas. Conclusões: A análise dos resultados obtidos sugere que evitar uma primeira cesariana e permitir o início espontâneo do trabalho de parto pode contribuir para o decréscimo a longo prazo da taxa de cesarianas. É fundamental um esforço coletivo para objetivar as suas indicações e que estas reflitam as orientações mais atualizadas relativas ao estado fetal não tranquilizador e ao trabalho de parto estacionário