1,598 research outputs found
Universal Conductance and Conductivity at Critical Points in Integer Quantum Hall Systems
The sample averaged longitudinal two-terminal conductance and the respective
Kubo-conductivity are calculated at quantum critical points in the integer
quantum Hall regime. In the limit of large system size, both transport
quantities are found to be the same within numerical uncertainty in the lowest
Landau band, and , respectively. In
the 2nd lowest Landau band, a critical conductance is
obtained which indeed supports the notion of universality. However, these
numbers are significantly at variance with the hitherto commonly believed value
. We argue that this difference is due to the multifractal structure
of critical wavefunctions, a property that should generically show up in the
conductance at quantum critical points.Comment: 4 pages, 3 figure
Outcomes for family medicine postgraduate training in South Africa
After 1994, the post-apartheid government decided that primary health care and the district health system would be the cornerstone of their new health policy. As a consequence of this, the academic departments of Family Medicine and primary care recognised the need for a nationally agreed set of training outcomes that were more aligned with these new priorities within the public sector. Thus in 2001, the Family Medicine Education Consortium (FaMEC), representing the eight academic departments of family medicine in South Africa, agreed to a set of outcomes for postgraduate family medicine training. At that time, all departments were running Family Medicine Master’s programmes as part-time training courses for doctors in primary health care. Recognition of the need to move towards full-time registrar training already existed, and because of this steps were taken to register Family Medicine as a speciality with the Health Professions Council of South Africa (HPCSA)
Critical level spacing distribution of two-dimensional disordered systems with spin-orbit coupling
The energy level statistics of 2D electrons with spin-orbit scattering are
considered near the disorder induced metal-insulator transition. Using the Ando
model, the nearest-level-spacing distribution is calculated numerically at the
critical point. It is shown that the critical spacing distribution is size
independent and has a Poisson-like decay at large spacings as distinct from the
Gaussian asymptotic form obtained by the random-matrix theory.Comment: 7 pages REVTeX, 2 uuencoded, gzipped figures; J. Phys. Condensed
Matter, in prin
Boundary multifractality in critical 1D systems with long-range hopping
Boundary multifractality of electronic wave functions is studied analytically
and numerically for the power-law random banded matrix (PRBM) model, describing
a critical one-dimensional system with long-range hopping. The peculiarity of
the Anderson localization transition in this model is the existence of a line
of fixed points describing the critical system in the bulk. We demonstrate that
the boundary critical theory of the PRBM model is not uniquely determined by
the bulk properties. Instead, the boundary criticality is controlled by an
additional parameter characterizing the hopping amplitudes of particles
reflected by the boundary.Comment: 7 pages, 4 figures, some typos correcte
Levitation of the quantum Hall extended states in the 0 limit
We investigate the fate of the quantum Hall extended states within a
continuum model with spatially correlated disorder potentials. The model can be
projected onto a couple of the lowest Landau bands. Levitation of the
critical states is observed if at least the two lowest Landau bands are
considered. The dependence on the magnetic length and
on the correlation length of the disorder potential is combined into a
single dimensionless parameter . This enables us to study
the behavior of the critical states for vanishing magnetic field. In the two
Landau band limit, we find a disorder dependent saturation of the critical
states' levitation which is in contrast to earlier propositions, but in accord
with some experiments.Comment: 7 pages, 9 figures. Replaced with published versio
The pion mass dependence of the nucleon form-factors of the energy momentum tensor in the chiral quark-soliton model
The nucleon form factors of the energy-momentum tensor are studied in the
large-Nc limit in the framework of the chiral quark-soliton model for model
parameters that simulate physical situations in which pions are heavy. This
allows for a direct comparison to lattice QCD results.Comment: 17 pages, 12 figure
Critical Level Statistics in Two-dimensional Disordered Electron Systems
The level statistics in the two dimensional disordered electron systems in
magnetic fields (unitary ensemble) or in the presence of strong spin-orbit
scattering (symplectic ensemble) are investigated at the Anderson transition
points. The level spacing distribution functions 's are found to be
independent of the system size or of the type of the potential distribution,
suggesting the universality. They behave as in the small region in
the former case, while rise is seen in the latter.Comment: LaTeX, to be published in J. Phys. Soc. Jpn. (Letter) Nov., Figures
will be sent on reques
Sivers effect in Drell Yan at RHIC
On the basis of a fit to the Sivers effect in deep-inelastic scattering, we
make predictions for single-spin asymmetries in the Drell-Yan process at RHIC.Comment: 10 pages, 7 figures, 1 table. v2: References and comments added,
minor correction
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