Magnetic flux periodicity of h/e in superconducting loops

The magnetic flux periodicity of superconducting loops as well as flux quantization itself are a manifestation of macroscopic quantum phenomena with far reaching implications. They provide the key to the understanding of many fundamental properties of superconductors and are the basis for most bulk and device applications of these materials. In superconducting rings the electrical current has been known to periodically respond to a magnetic flux with a periodicity of $\bm{h/2e}$. Here, the ratio of Planck's constant and the elementary charge defines the magnetic flux quantum $\bm{h/e}$. The well-known $\bm{h/2e}$ periodicity is viewed to be a hallmark for electronic pairing in superconductors and is considered evidence for the existence of Cooper pairs. Here we show that in contrast to this long-term belief, rings of many superconductor bear an $\bm{h/e}$ periodicity. These superconductors include the high-$\bm{T_c}$ cuprates, Sr$_2$RuO$_4$, the heavy-fermion superconductors, as well as all other unconventional superconductors with nodes in the energy gap functions, and s-wave superconductors with small gaps or states in the gap. As we show, the 50-year-old Bardeen--Cooper--Schrieffer theory of superconductivity implies that for multiply connected paths of such superconductors the ground-state energies and consequently also the supercurrents are generically $\bm{h/e}$ periodic. The origin of this periodicity is a magnetic-field driven reconstruction of the condensate and a concomitant Doppler-shifted energy spectrum. The robust, flux induced reconstruction of the condensate will be an important aspect to understand the magnetic properties of mesoscopic unconventional superconductors.Comment: To appear in Nature Physics (2008). The new version has the same main text and figures but also includes the supplementary material with a short Appendix A on the "Numerical Method" and a longer Appendix B on an analytical "Multichannel Model for Large D-Wave Rings

Cifose torácica e músculos isquiotibiais: correlação estético-funcional Thoracic kyphosis and hamstrings: an aesthetic-functional correlation

OBJETIVO: Os autores discutem a correlação existente entre a cifose torácica aumentada, em pacientes portadores de Dorso Curvo Postural (DCP) ou Doença de Scheuermann (DS), e a contratura dos músculos isquiotibiais. Esta relação é pouco estudada na literatura. MÉTODOS: No período de junho a dezembro de 2003, foram analisados 38 pacientes. Dentre os pacientes, 26 (68,4 %) eram do sexo masculino e 12 (31,6%) do sexo feminino. A idade mínima foi de 10 anos e a máxima de 20 anos, com média de 15,36. Encontramos 20 (52,6%) pacientes portadores de Doença de Scheuermann e 18 (47,4%) com Dorso Curvo Postural. RESULTADOS: De todos os 38 pacientes estudados, 32 (84,2%) apresentaram contratura dos isquiotibiais, o que foi estatisticamente significante (p<0,001). Analisando apenas pacientes com DS encontramos 85% de contratura e 83,3% nos com DCP. CONCLUSÃO: Não houve diferença estatística, da porcentagem de contratura dos isquiotibiais na DS em relação ao DCP (p=0,61).<br>OBJECTIVE: The authors discuss the existent correlation between augmented thoracic kyphosis in patients with juvenile Kyphosis or Scheuermann`s disease and hamstrings contraction. This correlation is marginally addressed by existing studies. METHODS: Between June and December 2003, 38 patients belonging to the Spine Group at the Department of Orthopaedics from Santa Casa de São Paulo, Brazil, were analyzed. Among them, 26 (68.4%) were males and 12 (81.6%) were females. The youngest age was 10 and the oldest one was 20 years, with an average of 15.36. Twenty (52.6%) patients presented with Scheuermann&acute;s disease and 18 (47.4%) with juvenile Kyphosis. RESULTS: From all 38 patients under study, 32 (84.2%) presented hamstring contracture, which was statistically significant (p<0.001). 85% of patients presenting only Scheuermann`s disease and 83.3% of patients with only juvenile Kyphosis had contracture. Conclusion: There was no statistically significant difference between contraction percentage in Scheuermann`s disease patients versus juvenile Kyphosis patients (p=0.61)