DC Josephson Effect in SNS Junctions of Anisotropic Superconductors

A formula for the Josephson current between two superconductors with anisotropic pairing symmetries is derived based on the mean-field theory of superconductivity. Zero-energy states formed at the junction interfaces is one of basic phenomena in anisotropic superconductor junctions. In the obtained formula, effects of the zero-energy states on the Josephson current are taken into account through the Andreev reflection coefficients of a quasiparticle. In low temperature regimes, the formula can describe an anomaly in the Josephson current which is a direct consequence of the exsitence of zero-energy states. It is possible to apply the formula to junctions consist of superconductors with spin-singlet Cooper pairs and those with spin-triplet Cooper pairs

Lowest-Landau-level theory of the quantum Hall effect: the Fermi-liquid-like state

A theory for a Fermi-liquid-like state in a system of charged bosons at filling factor one is developed, working in the lowest Landau level. The approach is based on a representation of the problem as fermions with a system of constraints, introduced by Pasquier and Haldane (unpublished). This makes the system a gauge theory with gauge algebra W_infty. The low-energy theory is analyzed based on Hartree-Fock and a corresponding conserving approximation. This is shown to be equivalent to introducing a gauge field, which at long wavelengths gives an infinite-coupling U(1) gauge theory, without a Chern-Simons term. The system is compressible, and the Fermi-liquid properties are similar, but not identical, to those in the previous U(1) Chern-Simons fermion theory. The fermions in the theory are effectively neutral but carry a dipole moment. The density-density response, longitudinal conductivity, and the current density are considered explicitly.Comment: 32 pages, revtex multicol

Microwave determination of the quasiparticle scattering time in YBa2Cu3O6.95

We report microwave surface resistance (Rs) measurements on two very-high-quality YBa2Cu3O6.95 crystals which exhibit extremely low residual loss at 1.2 K (2-6 μΩ at 2 GHz), a broad, reproducible peak at around 38 K, and a rapid increase in loss, by 4 orders of magnitude, between 80 and 93 K. These data provide one ingredient in the determination of the temperature dependence of the real part of the microwave conductivity, σ1(T), and of the quasiparticle scattering time. The other necessary ingredient is an accurate knowledge of the magnitude and temperature dependence of the London penetration depth, λ(T). This is derived from published data, from microwave data of Anlage, Langley, and co-workers and from, high-quality μSR data. We infer, from a careful analysis of all available data, that λ2(0)/λ2(T) is well approximated by the simple function 1-t2, where t=T/Tc, and that the low-temperature data are incompatible with the existence of an s-wave, BCS-like gap. Combining the Rs and λ(T) data, we find that σ1(T), has a broad peak around 32 K with a value about 20 times that at Tc. Using a generalized two-fluid model, we extract the temperature dependence of the quasiparticle scattering rate which follows an exponential law, exp(T/T0), where T0≊12 K, for T between 15 and 84 K. Such a temperature dependence has previously been observed in measurements of the nuclear spin-lattice relaxation rate. Both the uncertainties in our analysis and the implications for the mechanism of high-temperature superconductivity are discussed

Fisioterapia após substituição artroscópica do ligamento cruzado cranial em cães: I - avaliação clínica, radiográfica e ultrassonográfica Physiotherapy after arthroscopic repair of the cranial cruciate ligament in dogs: I - clinical, radiographic, and ultrasonographic evaluation

Foram avaliadas a aplicabilidade da cirurgia artroscópica na substituição do ligamento cruzado cranial (LCC) e o efeito da fisioterapia pós-operatória, por meio de exames clínicos, radiográficos e ultrassonográficos, em 16 cães sem raça definida, machos, com pesos entre 19,2 e 26,3kg, submetidos à ruptura experimental do LCC e subsequente substituição deste ligamento pelo enxerto autógeno da fascia lata. Os animais foram distribuídos em dois grupos de oito cada: no grupo I os cães foram submetidos ao programa de fisioterapia pós-operatória e no grupo II à imobilização temporária do membro. Por meio dos exames citados, não foram verificadas diferenças significativas entre os dois grupos, e ambos demonstraram sinais de processo articular degenerativo. A função do membro foi avaliada com auxílio da plataforma de força, e os animais do grupo I apresentaram melhor apoio do membro operado durante o período de reabilitação. Conclui-se que a cirurgia artroscópica é uma técnica eficaz para substituição do LCC em cães, apesar de não impedir o desenvolvimento da doença articular degenerativa, e que a fisioterapia permite recuperação mais rápida no apoio do membro durante o período de reabilitação.<br>The reconstruction of experimentally ruptured cranial cruciate ligament (CCL) under arthroscopic guidance and the effects of an early postoperative rehabilitation program by clinical, radiographic, and ultrasonographic exams were evaluated. Sixteen male mongrel dogs weighing from 19.2 to 26.3kg had the CCL experimentally ruptured and the stifle joint was stabilized by the use of an intracapsular arthroscopical technique with fascia lata as an autogenous graft. Eight dogs were included in a postoperative physiotherapy group and the other eight in a temporary immobilization group. From serial clinical, radiographic, and ultrasonographic examinations, no differences between groups were observed, although all dogs had showed signs of degenerative joint disease. Limb function was determined after surgery using force platform analysis, and the animals from physiotherapy group had significantly better results during rehabilitation period. It can be concluded that arthroscopic surgery for reconstruction of the cranial cruciate ligament is an efficient method to be used in dogs, in spite of not preventing the degenerative joint disease, and the physiotherapy has beneficial effects on early limb function during the rehabilitation period

Fisioterapia após substituição artroscópica do ligamento cruzado cranial em cães: II - avaliação artroscópica e anatomopatológica Physiotherapy after arthroscopic repair of the cranial cruciate ligament in dogs: II - Arthroscopic and anatomopathological evaluations

Avaliou-se o enxerto da fascia lata na substituição artroscópica do ligamento cruzado cranial (LCC), realizou-se a caracterização histológica do enxerto e da interface enxerto-osso e avaliou-se, por meio de exames artroscópicos e anatomopatológicos, o efeito da fisioterapia pós-operatória. Foram utilizados 16 cães, sem raça definida, machos, pesando entre 19,2 e 26,3kg, submetidos à ruptura experimental do LCC e subsequente substituição artroscópica desse ligamento pelo enxerto autógeno da fascia lata. Os animais foram distribuídos em dois grupos de oito cada: no grupo I, os cães foram submetidos ao programa de fisioterapia pós-operatória e, no grupo II, à imobilização temporária do membro. Os exames artroscópicos e histológicos mostraram alterações articulares sugestivas de processo degenerativo aos 60 dias após a cirurgia, que se apresentavam mais acentuadas nos cães do grupo II. Na análise histológica do enxerto, observou-se reorganização das fibras colágenas, que ocorreu de forma mais intensa e precoce nos animais do grupo I. Houve progressiva integração das fibras colágenas na interface enxerto-osso. Conclui-se que é viável utilizar a fascia lata como substituto do LCC por cirurgia artroscópica, que o enxerto sofre processos de ligamentação e de osteointegração, e que a fisioterapia reduz a progressão das alterações degenerativas e incentiva o processo de ligamentação do enxerto.<br>The fascia lata graft in the arthroscopic reconstruction of the cranial cruciate ligament (CCL), the histological characteristics of the graft and the graft-bone interface, and the effects of postoperative physiotherapy by arthroscopic and anatomopathological exams were evaluated. Sixteen male mongrel dogs weighing from 19.2 to 26.3kg had the CCL experimentally ruptured and the stifle joint was stabilized by arthroscopical technique with fascia lata as an autogenous graft. Eight dogs were included in a postoperative physiotherapy group and the other eight in a temporary immobilization group. Arthroscopic and histological examinations showed articular lesions consistent with degenerative joint disease at 60 days after surgery, which was more severe in dogs from the temporary immobilization group. From histological studies, the graft underwent a collagenic reorganization process that was more intense and earlier in dogs from the physiotherapy group. There was a progressive establishment of collagen fiber continuity in the graft-bone interface. It can be concluded that fascia lata graft can be used to replace the CCL by arthroscopic surgery, the graft undergo a ligamentization and osteointegration process, and the postoperative physiotherapy decrease the degenerative joint disease progression and stimulate the ligamentization of the graft