4,434 research outputs found

    Non-adiabatic Current Excitation in Quantum Rings

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    We investigate the difference in the response of a one-dimensional semiconductor quantum ring and a finite-width ring to a strong and short-lived time-dependent perturbation in the THz regime. In both cases the persistent current is modified through a nonadiabatic change of the many-electron states of the system, but by different mechanisms in each case.Comment: LaTeX, 5 pages with 6 embedded postscript figures, submitted to 20th Nordic Semiconductor Meeting, Tampere (2003

    Third edge for a graphene nanoribbon: A tight-binding model calculation

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    The electronic and transport properties of an extended linear defect embedded in a zigzag nanoribbon of realistic width are studied, within a tight binding model approach. Our results suggest that such defect profoundly modify the properties of the nanoribbon, introducing new conductance quantization values and modifying the conductance quantization thresholds. The linear defect along the nanoribbon behaves as an effective third edge of the system, which shows a metallic behavior, giving rise to new conduction pathways that could be used in nanoscale circuitry as a quantum wire.Comment: 6 pages, 6 figures. Two new figures and a few references adde

    Carrier scattering, mobilities and electrostatic potential in mono-, bi- and tri-layer graphenes

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    The carrier density and temperature dependence of the Hall mobility in mono-, bi- and tri-layer graphene has been systematically studied. We found that as the carrier density increases, the mobility decreases for mono-layer graphene, while it increases for bi-layer/tri-layer graphene. This can be explained by the different density of states in mono-layer and bi-layer/tri-layer graphenes. In mono-layer, the mobility also decreases with increasing temperature primarily due to surface polar substrate phonon scattering. In bi-layer/tri-layer graphene, on the other hand, the mobility increases with temperature because the field of the substrate surface phonons is effectively screened by the additional graphene layer(s) and the mobility is dominated by Coulomb scattering. We also find that the temperature dependence of the Hall coefficient in mono-, bi- and tri-layer graphene can be explained by the formation of electron and hole puddles in graphene. This model also explains the temperature dependence of the minimum conductance of mono-, bi- and tri-layer graphene. The electrostatic potential variations across the different graphene samples are extracted.Comment: 18 pages, 7 figure

    Model to Predict Duty of Community Nurses in Promotive and Preventive Care

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    Community nurses had important role in promotive and preventive care in community. Aim of the study was to make model to predict community nurses role in promotive and preventive care based on Health Promotion Model (HPM). Design of the study was used explanatory with cross sectional approach. Sum of participant was 161. This study was conducted in 11 Public Health Center in Banyuwangi at 1 January to 30 January 2018. Methods of data collection was cluster sampling. The data was analysed using smartPLS software.. Inner model: personal factors (t=1.981), interpersonal influences (t=4.036), situational influences (5.720), commitment (t=5.138) had affected to community nurses duty in promotive and preventive care. This model could predict community nurses duty in promotive and preventive care in high level (Q=0.998). That was important to enhance of community nurses duty through modifying commitment of nurses, interpersonal influence factors, personal factors and situational influence factors

    Bulk and shear relaxation in glasses and highly viscous liquids

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    The ratio between the couplings of a relaxational process to compression and shear, respectively, is calculated in the Eshelby picture of structural rearrangements within a surrounding elastic matrix, assuming a constant density of stable structures in distortion space. The result is compared to experimental data for the low-temperature tunneling states in glasses and to Prigogine-Defay data at the glass transition from the literature.Comment: 6 pages, 2 figures, 53 references; version after understanding the Prigogine-Defay ratio at the glass transition in the accompanying paper arXiv:1203.3555 [cond-mat.dis-nn

    Nano-wires with surface disorder: Giant localization lengths and quantum-to-classical crossover

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    We investigate electronic quantum transport through nano-wires with one-sided surface roughness. A magnetic field perpendicular to the scattering region is shown to lead to exponentially diverging localization lengths in the quantum-to-classical crossover regime. This effect can be quantitatively accounted for by tunneling between the regular and the chaotic components of the underlying mixed classical phase space.Comment: 4 pages, 3 figures; final version (including added references
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