37 research outputs found

    11^{11}B NMR detection of the magnetic field distribution in the mixed superconducting state of MgB2_2

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    The temperature dependence of the magnetic field distribution in the mixed superconducting phase of randomly oriented MgB2_2 powder was probed by 11% ^{11}B NMR spectroscopy. Below the temperature of the second critical (Bc2B_{% {c2}}) field, Tc227T_{{c2}}\approx 27K, our spectra reveal two NMR signal components, one mapping the magnetic field distribution in the mixed superconducting state and the other one arising from the normal state. The complementary use of bulk magnetization and NMR measurements reveals that MgB2_2 is an anisotropic superconductor with a Bc2c<2.35B_{c2}^c<2.35 Tesla anisotropy parameter γ6\gamma\approx 6

    Learning the \u27How\u27 of the Law: Teaching Procedure and Legal Education

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    This article examines the approaches to teaching civil procedure in five common law jurisdictions (Canada, Australia, United States, Israel, and England). The paper demonstrates the important transition of civil procedure from a vocational oriented subject to a rigorous intellectual study of policies, processes, and values underpinning our civil justice system, and analysis of how that system operates. The advantages and disadvantages of where civil procedure fits within the curriculum are discussed and the significant opportunities for ‘active’ learning are highlighted. The inclusion of England where civil procedure is not taught to any significant degree in the law degree provides a valuable comparator. Common findings from the other jurisdictions suggest that teaching civil procedure enhances the curriculum by bringing it closer to what lawyers actually do as well as enabling a better understanding of the development of doctrinal law

    Learning the \u27How\u27 of the Law: Teaching Procedure and Legal Education

    Get PDF
    This article examines the approaches to teaching civil procedure in five common law jurisdictions (Canada, Australia, United States, Israel, and England). The paper demonstrates the important transition of civil procedure from a vocational oriented subject to a rigorous intellectual study of policies, processes, and values underpinning our civil justice system, and analysis of how that system operates. The advantages and disadvantages of where civil procedure fits within the curriculum are discussed and the significant opportunities for ‘active’ learning are highlighted. The inclusion of England where civil procedure is not taught to any significant degree in the law degree provides a valuable comparator. Common findings from the other jurisdictions suggest that teaching civil procedure enhances the curriculum by bringing it closer to what lawyers actually do as well as enabling a better understanding of the development of doctrinal law

    Spin-polarized oxygen hole states in cation deficient La(1-x)CaxMnO(3+delta)

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    When holes are doped into a Mott-Hubbard type insulator, like lightly doped manganites of the La(1-x)CaxMnO3 family, the cooperative Jahn-Teller distortions and the appearance of orbital ordering require an arrangement of Mn(3+)/Mn(4+) for the establishment of the insulating canted antiferromagnetic (for x<=0.1), or of the insulating ferromagnetic (for 0.1<x<= 0.2) ground state. In the present work we provide NMR evidence about a novel and at the same time puzzling effect in La(1-x)CaxMnO(3+delta) systems with cation deficience. We show that in the low Ca-doping regime, these systems exhibit a very strong hyperfine field at certain La nuclear sites, which is not present in the stoichiometric compounds. Comparison of our NMR results with recent x-ray absorption data at the Mn K edge, suggests the formation of a spin-polarized hole arrangement on the 2p oxygen orbitals as the origin of this effect.Comment: 10 pages, 4 Figures, submitted to PR

    A magnetization and 11^{11}B NMR study of Mg1x_{1-x}Alx_xB2_2 superconductors

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    We demonstrate for the first time the magnetic field distribution of the pure vortex state in lightly doped Mg1x_{1-x}Alx_xB2_2 (x0.025x\leq 0.025) powder samples, by using 11^{11}B NMR in magnetic fields of 23.5 and 47 kOe. The magnetic field distribution at T=5 K is Al-doping dependent, revealing a considerable decrease of anisotropy in respect to pure MgB2_2. This result correlates nicely with magnetization measurements and is consistent with σ\sigma-band hole driven superconductivity for MgB2_2

    11^{11}B NMR study of pure and lightly carbon doped MgB2_2 superconductors

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    We report a 11^{11}B NMR line shape and spin-lattice relaxation rate (1/(T1T)1/(T_1T)) study of pure and lightly carbon doped MgB2x_{2-x}Cx_{x} for x=0x=0, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB2_2 exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase of Hc2cH_{c2}^c with carbon doping with respect to pure MgB2_2. The spin-lattice relaxation rate 1/(T1T)1/(T_1T) demonstrates clearly the presence of a coherence peak right below TcT_c in pure MgB2_2, followed by a typical BCS decrease on cooling. However, at temperatures lower than 10\approx 10K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon doped systems both the coherence peak and the BCS temperature dependence of 1/(T1T)1/(T_1T) weaken, an effect attributed to the gradual shrinking of the σ\sigma hole cylinders of the Fermi surface with electron doping.Comment: 8 pages, 6 figures, submitted to Phys. Rev.

    Diversity of Bacteria in Lakes with Different Chlorophyll Content and Investigation of Their Respiratory Activity through a Long-Term Microcosm Experiment

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    Bacterial community structure and metabolism are critical factors for ecosystem functioning since they affect remineralization of nutrients and carbon flow. We used Illumina sequencing of 16SrRNA V3-V4 regions to investigate whether bacterial assemblage composition differs between four samples from two lakes in the geographic region of Epirus (Greece) characterized by distinct oligotrophic to eutrophic/hypereutrophic conditions as revealed by chlorophyll-a values. We found high similarity (&gt;60%) for bacterial assemblages recovered from the two lakes when eutrophic/hypereutrophic conditions prevailed. Distinct bacterial communities appeared in oligotrophic and mesotrophic waters. Low temperature was occasionally an important factor in shaping the bacterial community. In parallel, microcosm experiments were performed to estimate respiration rates of bacterioplankton at in situ temperature and under a 2 &deg;C temperature increase scenario. Differently assembled communities were found to display similar rates except under hypereutrophic conditions when respiration increased significantly, leading to hypoxic conditions. Temperature increase did not affect respiration rates. Overall this study indicated a clear differentiation of bacterial communities between sites of different trophic state. However, different communities responded similarly under a specific range of chlorophyll-a values and resisted small scale temperature perturbations. Different results were found for hypereutrophic conditions and this has implications for ecosystems functioning, given the increasing occurrence of eutrophication events

    PRE-ERUPTIVE NEUROLOGIC MANIFESTATIONS ASSOCIATED WITH MULTIPLE CEREBRAL INFARCTS IN VARICELLA

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    A boy, 4 years, 9 months of age, presented with acute hemiplegia, lethargy, ataxia, and dysarthria 24 hours prior to the eruption of typical varicella exanthem. Magnetic resonance imaging findings were typical of multiple cerebral ischemic infarcts. It is suggested that during the period of secondary viremia varicella tester virus invaded the cerebral blood vessels causing vasculopathy and cerebrovascular infarcts
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