The SASPREN primary care survey - who consults the family doctor?

Objective. To describe selected characteristics of patients consulting general family practitioners in the Western Cape.Design. A cross-sectional survey design was employed in which doctors completed a structured questionnaire during or immediately after each consultation.Setting. Data were collected by family practitioners in private practice who were affiliated to the South African Sentinel Practitioner Research Network (SASPREN).Participants. All patients who had a face-to-face encounter wrth the doctor at his/her surgery. A total of 2 473 such encounters was included. Main outcome measures. Age, sex, race, method of payment and smoking status.Results. Females outnumbered males in all race groups except blacks, where they comprised 48% of patients. Most patients were under the age of 14 years (23.3%) or between 25 and 44 years (33.3%). However, after the demography of the ca1chment population was taken into account, the highest utilisation of general practitioner services was found to be at extremes of age. This utilisation pattern was demonstrated in both sexes and all races. In relation to their distribution in the population. whites and Indians are over~represented in private practice while blacks and coloureds are under-represented. The bulk of patients (67%) pay for general practitioner services via some form of insurance (medical aid or benefit fund). but significant differences exist across race groups. In the case of blacks and Indians, the majority (72% and 64% respectively) of consultations are funded 'out of pocket'. An alamingly high smoking prevalence was found in black and coloured men. In all race/sex groups smoking rates peak between 25 and 44 years. In this age group, 68.6% of black men and 73.3% of coloured men were current smokers.Conclusions. This study provides essential information on patients seen in family practice. Access to family doctor selVices in the Western Cape should be improved for blacks and coIoureds. There is an urgent need for smoking cessation interventions in the region

Steering effects on growth instability during step-flow growth of Cu on Cu(1,1,17)

Kinetic Monte Carlo simulation in conjunction with molecular dynamics simulation is utilized to study the effect of the steered deposition on the growth of Cu on Cu(1,1,17). It is found that the deposition flux becomes inhomogeneous in step train direction and the inhomogeneity depends on the deposition angle, when the deposition is made along that direction. Steering effect is found to always increase the growth instability, with respect to the case of homogeneous deposition. Further, the growth instability depends on the deposition angle and direction, showing minimum at a certain deposition angle off-normal to (001) terrace, and shows a strong correlation with the inhomogeneous deposition flux. The increase of the growth instability is ascribed to the strengthened step Erlich Schwoebel barrier effects that is caused by the enhanced deposition flux near descending step edge due to the steering effect.Comment: 5 page

Formation of plasma around a small meteoroid: 1. Kinetic theory

This article is a companion to Dimant and Oppenheim [2017] https://doi.org/10.1002/2017JA023963.This paper calculates the spatial distribution of the plasma responsible for radar head echoes by applying the kinetic theory developed in the companion paper. This results in a set of analytic expressions for the plasma density as a function of distance from the meteoroid. It shows that at distances less than a collisional mean free path from the meteoroid surface, the plasma density drops in proportion to 1/R where R is the distance from the meteoroid center; and, at distances much longer than the mean‐free‐path behind the meteoroid, the density diminishes at a rate proportional to 1/R2. The results of this paper should be used for modeling and analysis of radar head echoes.This work was supported by NSF grant AGS-1244842. (AGS-1244842 - NSF

Orbit equivalence rigidity for ergodic actions of the mapping class group

We establish orbit equivalence rigidity for any ergodic, essentially free and measure-preserving action on a standard Borel space with a finite positive measure of the mapping class group for a compact orientable surface with higher complexity. We prove similar rigidity results for a finite direct product of mapping class groups as well.Comment: 11 pages, title changed, a part of contents remove

Stimulated wave of polarization in spin chains

Stimulated wave of polarization, triggered by a flip of a single spin, presents a simple model of quantum amplification. Previously, it has been found that such wave can be excited in a 1D Ising chain with nearest-neighbor interactions, irradiated by a weak resonant transverse field. Here we explore models with more realistic Hamiltonians, in particular, with natural dipole-dipole interactions. Results of simulations for 1D spin chains and rings with up to nine spins are presented.Comment: 15 pages, 5 figure

Compound transfer matrices: Constructive and destructive interference

Scattering from a compound barrier, one composed of a number of distinct non-overlapping sub-barriers, has a number of interesting and subtle mathematical features. If one is scattering classical particles, where the wave aspects of the particle can be ignored, the transmission probability of the compound barrier is simply given by the product of the transmission probabilities of the individual sub-barriers. In contrast if one is scattering waves (whether we are dealing with either purely classical waves or quantum Schrodinger wavefunctions) each sub-barrier contributes phase information (as well as a transmission probability), and these phases can lead to either constructive or destructive interference, with the transmission probability oscillating between nontrivial upper and lower bounds. In this article we shall study these upper and lower bounds in some detail, and also derive bounds on the closely related process of quantum excitation (particle production) via parametric resonance.Comment: V1: 28 pages. V2: 21 pages. Presentation significantly streamlined and shortened. This version accepted for publication in the Journal of Mathematical Physic

Improved Analysis of J/psi Decays into a Vector Meson and Two Pseudoscalars

Recently, the BES collaboration has published an extensive partial wave analysis of experimental data on J/psi -> phi pi+pi-, J/psi -> omega pi+pi-, J/psi -> phi K+K- and J/psi -> omega K+K-. These new results are analyzed here, with full account of detection efficiencies, in the framework of a chiral unitary description with coupled-channel final state interactions between pi-pi and K-bar K pairs. The emission of a dimeson pair is described in terms of the strange and nonstrange scalar form factors of the pion and the kaon, which include the final state interaction and are constrained by unitarity and by matching to the next-to-leading-order chiral expressions. This procedure allows for a calculation of the S-wave component of the dimeson spectrum including the f_0(980) resonance, and for an estimation of the low-energy constants of Chiral Perturbation Theory, in particular the large N_c suppressed constants L_4^r and L_6^r. The decays in question are also sensitive to physics associated with OZI violation in the 0++ channel. It is found that the S-wave contributions to phi pi+pi-, phi K+K- and omega pi+pi- given by the BES partial-wave analysis may be very well fitted up to a dimeson center-of-mass energy of ~1.2 GeV, for a large and positive value of L_4^r and a value of L_6^r compatible with zero. An accurate determination of the amount of OZI violation in the J/psi -> phi pi+pi- decay is achieved, and the S-wave contribution to omega K+K- near threshold is predicted.Comment: 18 pages, 6 figures, title changed, accepted version for PR

Encounter complexes and dimensionality reduction in protein-protein association

An outstanding challenge has been to understand the mechanism whereby proteins associate. We report here the results of exhaustively sampling the conformational space in protein–protein association using a physics-based energy function. The agreement between experimental intermolecular paramagnetic relaxation enhancement (PRE) data and the PRE profiles calculated from the docked structures shows that the method captures both specific and non-specific encounter complexes. To explore the energy landscape in the vicinity of the native structure, the nonlinear manifold describing the relative orientation of two solid bodies is projected onto a Euclidean space in which the shape of low energy regions is studied by principal component analysis. Results show that the energy surface is canyon-like, with a smooth funnel within a two dimensional subspace capturing over 75% of the total motion. Thus, proteins tend to associate along preferred pathways, similar to sliding of a protein along DNA in the process of protein-DNA recognition

Steering effect on the shape of islands for homoepitaxial growth of Cu on Cu(100)

The steering effect on the growth of islands is investigated by combining molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations. Dynamics of depositing atoms and kinetics of atoms on a substrate are realized by MD and KMC, respectively. The reported experimental results on the asymmetric island growth [van Dijken {\it et al.}, Phys. Rev. Lett. {\bf 82}, 4038 (1999).] is well reproduced. A salient phenomenon, the reversal of the asymmetry, is found as the island size increases, and attributed to the asymmetric flux on the lower terrace of island.Comment: 5 figur

Analysis of a three-component model phase diagram by Catastrophe Theory

We analyze the thermodynamical potential of a lattice gas model with three components and five parameters using the methods of Catastrophe Theory. We find the highest singularity, which has codimension five, and establish its transversality. Hence the corresponding seven-degree Landau potential, the canonical form Wigwam or $A_6$, constitutes the adequate starting point to study the overall phase diagram of this model.Comment: 16 pages, Latex file, submitted to Phys. Rev.