509 research outputs found

    Elastic Properties and Magnetic Phase Diagrams of Dense Kondo Compound Ce0.75La0.25B6

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    We have investigated the elastic properties of the cubic dense Kondo compound Ce0.75La0.25B6 by means of ultrasonic measurements. We have obtained magnetic fields vs temperatures (H-T) phase diagrams under magnetic fields along the crystallographic [001], [110] and [111] axes. An ordered phase IV showing the elastic softening of c44 locates in low temperature region between 1.6 and 1.1 K below 0.7 T in all field directions. The phase IV shows an isotropic nature with regard to the field directions, while the antiferro-magnetic phase III shows an anisotropic character. A remarkable softening of c44 and a spontaneous trigonal distortion εyz+εzx+εxy recently reported by Akatsu et al. [J. Phys. Soc. Jpn. 72 (2003) 205] in the phase IV favor a ferro-quadrupole (FQ) moment of Oyz+Ozx+Oxy induced by an octupole ordering.Comment: 9 figures, Strongly Correlated Electron

    Magnetic edge states of impenetrable stripe

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    The electron motion in a strong perpendicular magnetic field close to the impenetrable stripe is considered by making use of the singular integral equation technique. The energy spectrum is calculated and compared with the energy spectrum of the round antidot.Comment: REVTeX4 format, 9 pages with 9 figures (*.eps

    Critical Phenomena at the Antiferromagnetic Phase Transition of Azurite

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    We report on high-resolution acoustic, specific-heat and thermal expansion measurements in the vicinity of the antiferromagnetic phase transition at T_N = 1.88 K on a high-quality single crystal of the natural mineral azurite. A detailed investigation of the critical contribution to the various quantities at T_N is presented. The set of critical exponents and amplitude ratios of the singular contributions above and below the transition indicate that the system can be reasonably well described by a three-dimensional Heisenberg antiferromagnet.Comment: 9 pages, 3 figures, proceedings of ICM 2012, JKP

    Ultrasound Investigations of Orbital Quadrupolar Ordering in UPd_3

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    For a high-quality single crystal of UPd_3 we present the relevant elastic constants and ultrasonic attenuation data. In addition to the magnetic phase transition at T_2=4.4 +/- 0.1K and the quadrupolar transition at T_1~6.8K, we find orbital ordering at T_0=7.6 +/- 0.1K concomitant with a symmetry change from hexagonal to orthorhombic. A striking feature is the splitting of the phase transition at T_1 into a second-order transition at T_{+1}=6.9 +/- 0.05K and a first-order transition at T_{-1}=6.7 +/- 0.05K. For the four phase transitions, the quadrupolar order parameters and the respective symmetry changes are specified.Comment: 14 pages (RevTex), 3 eps-figures, accepted by PR

    Continuous mode cooling and phonon routers for phononic quantum networks

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    We study the implementation of quantum state transfer protocols in phonon networks, where in analogy to optical networks, quantum information is transmitted through propagating phonons in extended mechanical resonator arrays or phonon waveguides. We describe how the problem of a non-vanishing thermal occupation of the phononic quantum channel can be overcome by implementing optomechanical multi- and continuous mode cooling schemes to create a 'cold' frequency window for transmitting quantum states. In addition, we discuss the implementation of phonon circulators and switchable phonon routers, which rely on strong coherent optomechanical interactions only, and do not require strong magnetic fields or specific materials. Both techniques can be applied and adapted to various physical implementations, where phonons coupled to spin or charge based qubits are used for on-chip networking applications.Comment: 33 pages, 8 figures. Final version, a few minor changes and updated reference

    Measurement Properties of ID-PALL, A New Instrument for the Identification of Patients With General and Specialized Palliative Care Needs.

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    To improve access to palliative care, identification of patients in need of general or specialized palliative care is necessary. To our knowledge, no available identification instrument makes this distinction. ID-PALL is a screening instrument developed to differentiate between these patient groups. To assess the structural and criterion validity and the inter-rater agreement of ID-PALL. In this multicenter, prospective, cross-sectional study, nurses and physicians assessed medical patients hospitalized for 2 to 5 days in two tertiary hospitals in Switzerland using ID-PALL. For the criterion validity, these assessments were compared to a clinical gold standard evaluation performed by palliative care specialists. Structural validity, internal consistency and inter-rater agreement were assessed. 2232 patients were assessed between January and December 2018, 97% by nurses and 50% by physicians. The variances for ID-PALL G and S are explained by two factors, the first one explaining most of the variance in both cases. For ID-PALL G, sensitivity ranged between 0.80 and 0.87 and specificity between 0.56 and 0.59. ID-PALL S sensitivity ranged between 0.82 and 0.94, and specificity between 0.35 and 0.64. A cut-off value of 1 delivered the optimal values for patient identification. Cronbach's alpha was 0.78 for ID-PALL G and 0.67 for ID-PALL S. The agreement rate between nurses and physicians was 71.5% for ID-PALL G and 64.6% for ID-PALL S. ID-PALL is a promising screening instrument allowing the early identification of patients in need of general or specialized palliative care. It can be used by nurses and physicians without a specialized palliative care training. Further testing of the finalized clinical version appears warranted

    Impact of an interdisciplinary strategy on antibiotic use: a prospective controlled study in three hospitals

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    Objectives: Evaluation of the impact of the implementation of practice guidelines, with or without their reinforcement by a pharmacist, on the intra-hospital use of antibiotics. Materials and methods: The duration of antibiotic treatment, their cost, and the length of patient stay were compared in three secondary-care hospitals, before and after interventions that were designed to promote rational antibiotic use. After randomization, hospital A received no intervention (control), local practice guidelines were implemented in hospital B (low grade intervention), and these guidelines were reinforced by a clinical pharmacist in hospital C (high grade intervention). Adherence to the guidelines was measured in hospitals B and C. Multivariable statistical analyses were carried out to adjust for confounding factors. Results: None of the outcomes measured in the 1200 included patients decreased between the two study periods in any hospital. Hospital A was significantly and independently associated with an increase in the duration of antibiotic treatments, the cost of antibiotics (acquisition and global costs), and the length of stay. Although these differences were not statistically significant, increases in hospital B were higher than in hospital C. Adherence to guidelines was significantly higher in hospital C. Conclusions: Even though interdisciplinary interventions aiming at rationalizing antibiotic use could not diminish the duration of treatments, their costs or the length of stay, they proved useful to control the progression of these parameter

    Anomalous elastic softening of SmRu_{4}P_{12} under high pressure

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    The filled skutterudite compound SmRu_4P_{12} undergoes a complex evolution from a paramagnetic metal (phase I) to a probable multipolar ordering insulator (phase II) at T_{MI} = 16.5 K, then to a magnetically ordered phase (phase III) at T_{N} = 14 K. Elastic properties under hydrostatic pressures were investigated to study the nature of the ordering phases. We found that distinct elastic softening above T_{MI} is induced by pressure, giving evidence of quadrupole degeneracy of the ground state in the crystalline electric field. It also suggests that quadrupole moment may be one of the order parameters below T_{MI} under pressure. Strangely, the largest degree of softening is found in the transverse elastic constant C_{T} at around 0.5-0.6 GPa, presumably having relevancy to the competing and very different Gruneisen parameters \Omega of T_{MI} and T_{N}. Interplay between the two phase transitions is also verified by the rapid increase of T_{MI} under pressure with a considerably large \Omega of 9. Our results can be understood on the basis of the proposed octupole scenario for SmRu_4P_{12}.Comment: 7 pages, 7 figure

    Geometrical quadrupolar frustration in DyB4_4

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    Physical properties of DyB4_4 have been studied by magnetization, specific heat, and ultrasonic measurements. The magnetic entropy change and the ultrasonic properties in the intermediate phase II indicate that the degeneracy of internal degrees of freedom is not fully lifted in spite of the formation of magnetic order. The ultrasonic attenuation and the huge softening of C44C_{44} in phase II suggests existence of electric-quadrupolar (orbital) fluctuations of the 4ff-electron. These unusual properties originate from the geometrical quadrupolar frustration.Comment: 4 pages, 4 figures, accepted for publication in Journal of the Physical Society of Japa
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