Universal single level implicit algorithm for gasdynamics

A single level effectively explicit implicit algorithm for gasdynamics is presented. The method meets all the requirements for unconditionally stable global iteration over flows with mixed supersonic and supersonic zones including blunt body flow and boundary layer flows with strong interaction and streamwise separation. For hyperbolic (supersonic flow) regions the method is automatically equivalent to contemporary space marching methods. For elliptic (subsonic flow) regions, rapid convergence is facilitated by alternating direction solution sweeps which bring both sets of eigenvectors and the influence of both boundaries of a coordinate line equally into play. Point by point updating of the data with local iteration on the solution procedure at each spatial step as the sweeps progress not only renders the method single level in storage but, also, improves nonlinear accuracy to accelerate convergence by an order of magnitude over related two level linearized implicit methods. The method derives robust stability from the combination of an eigenvector split upwind difference method (CSCM) with diagonally dominant ADI(DDADI) approximate factorization and computed characteristic boundary approximations

Termination of the solar wind in the hot, partially ionized interstellar medium

Theoretical foundations for understanding the problem of the termination of the solar wind are reexamined in the light of most recent findings concerning the states of the solar wind and the local interstellar medium. The investigation suggests that a simple extention of Parker's (1961) analytical model provides a useful approximate description of the combined solar wind, interstellar wind plasma flowfield under conditions presently thought to occur. A linear perturbation solution exhibiting both the effects of photoionization and charge exchange is obtained for the supersonic solar wind. A numerical algorithm is described for computing moments of the non-equilibrium hydrogen distribution function and associated source terms for the MHD equations. Computed using the algorithm in conjunction with the extended Parker solution to approximate the plasma flowfield, profiles of hydrogen number density are given in the solar wind along the upstream and downstream axes of flow with respect to the direction of the interstellar wind. Predictions of solar Lyman-alpha backscatter intensities to be observed at 1 a.u. have been computed, in turn, from a set of such hydrogen number density profiles varied over assumed conditions of the interstellar wind

From research to policy in chronic disease prevention: mandatory salt reduction in South Africa

Abstract of a poster that presented at 20th International Congress of Nutrition, Granada, Spain, September 15-20, 2013

Students get wise about AIDS - The acceptability, feasibility and impact of an AIDS education programme in a suburban school in Cape Town

Objectives. The study assessed the acceptability and feasibility of an AIDS education programme for South African high-school students.Design, setting and sUbjects. A 'before-after' study was conducted in a suburban high school in Cape Town. All 232 standard 8 students were included, and were exposed to the programme over 9 months.Outcome measures. Students' knowledge about AIDS and sexually transmitted diseases (SIDs), attitudes towards people with AIDS and towards AIDS prevention, perceptions of self-efficacy with regard to risk reduction, self-reported behaviour and opinions on the programme were measured using questionnaires. In addition, teachers' opinions of and experiences with the programme were assessed.Results. After the programme, significantly more students knew how to protect themselves from HIV, could identity the symptoms of STOs and understood why people with STOs had a higher risk of becoming infected with HIV. After the programme, significantly more students believed that they knew how to use a condom (77% at baseline, 88.6% at follow-up; P < 0.01). Prior to the programme only 20.8% of the students reported ever having had sexual intercourse. After the programme, significantly more students (32.8%) reported having had sexual intercourse. Most students (80.5%) reported that the programme had helped them to make plans to protect themselves from HIV infection. Teachers found the programme valuable and easy to use.Conclusions. There are severaJ South African school programmes such as 'Get Wise about AIDS' which have been shown to be acceptable and feasible, and which seem to be effective. Randomised controlled trials are now needed to provide conclusive evidence of their effectiveness

The size of two-body weakly bound objects : short versus long range potentials

The variation of the size of two-body objects is investigated, as the separation energy approaches zero, with both long range potentials and short range potentials having a repulsive core. It is shown that long range potentials can also give rise to very extended systems. The asymptotic laws derived for states with angular momentum l=1,2 differ from the ones obtained with short range potentials. The sensitivity of the asymptotic laws on the shape and length of short range potentials defined by two and three parameters is studied. These ideas as well as the transition from the short to the long range regime for the l=0 case are illustrated using the Kratzer potential.Comment: 5 pages, 3 figures, submitted to Physical Review Letter

Fungi Associated with Decay in Treated Southern Pine Utility Poles in the Eastern United States

Approximately 1,320 fungi were isolated and studied from 246 creosote- or pentachlorophenol-treated southern pine poles in service in the eastern United States. The fungi identified were Basidiomycete decayers, soft rotters, and microfungi. White rot fungi predominated in the 262 Basidiomycete decayers isolated from 180 poles. The major Basidiomycetes isolated by radial position from poles of varying service ages appeared to develop initially in the outer treated zones and were often associated with seasoning checks. Some decay origins, however, appeared to be cases of preinvasion and escapes of preservative treatment. Five species of soft rot fungi comprised nearly 85% of 211 isolates obtained from 131 poles. They were isolated primarily from creosote-treated poles in outer treated zones at the groundline. Dissection analysis of 92 poles indicated that six developmental decay patterns and certain fungi were associated commonly with a pattern. The pole mycoflora isolated was relatively uniform in distribution in the eastern United States. The soft rotters and white rot group of Basidiomycete decayers appear to be a more important component of the treated southern pine pole mycoflora than has been recognized previously

Improving cost-effectiveness of hypertension management at a community health centre

Objectives. To describe the pattern of prescribing for hypertension at a community health centre (CHC) and to evaluate the impact of introducing treatment guidelines and restricting availability of less cost-effective antihypertensive drugs on prescribing patterns, costs of drug treatment and blood pressure (BP) control.Design. Before/after intervention study.Setting. Medium-sized CHC in the Cape Flats area of Cape Town.Subjects. 1 084 hypertensive patients attending the CHC, who had at least two prescriptions for antihypertensive drugs during a 1-year period starting on 1 January 1992. Interventions. 1. Implementation of stepped-care guidelines for hypertension, specifying treatment with more cost-effective drugs and minimising drug treatment. 2. Reducing availability for routine prescribing by CHC doctors of 10 less cost-effective antihypertensive drugs or drug combinations.Outcome measures. 1. Mean number of drugs prescribed per patient. 2. Proportion of prescriptions for: each major class of antihypertensive drug; restricted availability and freely prescribable drugs; and more and less cost-effective drugs. 3. Mean monthly cost of drugs prescribed per patient. 4. Mean blood pressure and proportion of BP readings controlled (<160/95 mmHg) or uncontrolled (≥160/95 mmHg).Results. A mean of 1.7 active drugs was prescribed per patient per visit. The most frequently prescribed drugs were thiazide-like diuretics (44.8%), centrally acting agents (28.4%) and b-blockers (13.2%). Mean monthly drug costs per patient decreased significantly by R1.99 (24.2%) from R8.24 to R6.25 between the first and last prescription for each patient (exclusive of any reduction due to withdrawal of treatment). This was attributable to reduced prescribing of more expensive drugs withdrawn from routine use and a 51.1% increase in prescribing of the most cost-effective drugs. The overall annual cost-saving of the changes in prescribing for this CHC are estimated at R75 150. Blood pressure control did not change significantly.Conclusion. The pattern of changes in prescribing and drug costs was consistent with a causal effect of the interventions. The study demonstrates the potential forimproving cost-effectiveness of hypertension care in primary care in South Africa and the potential for research in this setting

Final technology report for D-Area oil seepage basin bioventing optimization test, environmental restoration support

One method proposed for the cleanup of the D-Area Oil Seepage Basin was in situ bioremediation (bioventing), involving the introduction of air and gaseous nutrients to stimulate contaminant degradation by naturally occurring microorganisms. To test the feasibility of this approach, a bioventing system was installed at the site for use in optimization testing by the Environmental Biotechnology Section of the Savannah River Technology Center. During the interim action, two horizontal wells for a bioventing remediation system were installed eight feet below average basin grade. Nine piezometers were also installed. In September of 1996, a generator, regenerative blower, gas cylinder station, and associated piping and nutrient injection equipment were installed at the site and testing was begun. After baseline characterization of microbial activity and contaminant degradation at the site was completed, four injection campaigns were carried out. These consisted of (1) air alone, (2) air plus triethylphosphate (TEP), (3) air plus nitrous oxide, and (4) air plus methane. This report describes results of these tests, together with conclusions and recommendations for further remediation of the site. Natural biodegradation rates are high. Oxygen, carbon dioxide, and methane levels in soil gas indicate substantial levels of baseline microbial activity. Oxygen is used by indigenous microbes for biodegradation of organics via respiration and hence is depleted in the soil gas and water from areas with high contamination. Carbon dioxide is elevated in contaminated areas. High concentrations of methane, which is produced by microbes via fermentation once the oxygen has been depleted, are found at the most contaminated areas of this site. Groundwater measurements also indicated that substantial levels of natural contaminant biodegradation occurred prior to air injection

Hypertension care at a Cape Town community health centre

Objectives. To describe the demographic profile of hypertensive patients and the quality of care for hypertension at a Cape Town community health centre (CHC).Design. Prospective, descriptive study.Setting and subjects. Medium-sized CHC, attended by 1098 hypertensive patients during a 1-year period from 1 January 1992.Outcome measures. Default rate - proportion of due visits not attended. Loss to follow-up - proportion of patients persistently defaulting or not responding to recall. Frequency of blood pressure measurement - per 12 due visits. Compliance - proportion of patients collecting ≥ 75% of antihypertensive drugs. Blood pressure control - mean blood pressure of aggregated readings; and proportion controlled (<160/95 mmHg) on the basis of all blood pressure readings and mean blood pressures of individual patients with two or more readings during the study period.Results. More than half (51.6%) of the hypertensive patients were aged ≥ 65 years; 81.7% were female. The default rate was between 11.9% and 19.4%. Compliance was high (76.9%). Loss to follow-up was 8.1 %. Blood pressure was recorded a mean of 4.0 times per 12 due visits. There were no significant gender differences with regard to these measures. Mean blood pressure was 158.3/89.6 mmHg. Over half (56.7%) of all individual readings over the year were uncontrolled and 51.4% of patients were found to be uncontrolled when categorised by their mean blood pressure. Control was significantly poorer among women ≥ 65 years.Conclusion. We found better compliance, more frequent blood pressure measurement, and lower defaulting and loss to follow-up compared with previous South African studies in similar settings. Despite this, blood pressure control was mediocre. Possible explanations for this are discussed. The low proportion of male hypertensives attending the CHC suggests that the accessibility or acceptability of care is poor for this group. The study illustrates the potential for research in this setting and for the use of computers to monitor the quality of primary care.

HIV care coverage among HIV-positive adolescent girls and young women in South Africa: Results from the HERStory Study

Background. Health service coverage cascades measure the proportion of a population in need of a service that experienced a positive health outcome from the service, and enable tracking of progress in achieving universal health coverage and inequities in care coverage.Objectives. To investigate HIV care coverage among HIV-positive adolescent girls and young women (AGYW) living in six South African districts, compare coverage by age and socioeconomic status (SES), and investigate other associated factors including participation in a combination HIV prevention intervention.Methods. The HERStory Study was an evaluation of the combination intervention, comprising a representative household survey of AGYW aged 15 - 24 years living in six intervention districts. From September 2017 to November 2018, biological, sociodemographic and behavioural data were collected. HIV-positive status, initiation of antiretroviral therapy (ART) and viral suppression were determined through laboratory tests (enzyme-linked immunosorbent assay for HIV antibodies, antiretroviral (ARV) metabolites and viral load (VL) testing). Viral suppression was defined as a VL <1 000 copies/mL. Knowledge of HIV-positive status was self-reported, and participants testing positive for ARV metabolites were assumed to have known their HIV-positive status. Unconditional HIV care cascades were created, stratified by age and SES. We used Pearson’s χ2 tests corrected for survey-based analysis to describe factors associated with knowledge of HIV status, and being on ART.Results. Of the 4 399 participants, 568 were HIV-positive (12.4%), of whom 60.8% (95% confidence interval (CI) 57.1 - 64.5) knew their status, 50.6% (95% CI 46.6 - 54.0) were on ART, and 62.1% (95% CI 58.4 - 65.9) were virally suppressed. Most participants (84.9%) were in the lower SES group, and they had better coverage than the higher SES group: 61.9% (95% CI 58.3 - 65.4) knew their status, 52.1% (95% CI 48.4 - 55.9) were on ART, and 64.9% (95% CI 61.3 - 68.4) were virally suppressed, compared with 55.0% (95% CI 42.1 - 68.0), 40.0% (95% CI 29.2 - 50.8), and 46.6% (95% CI 34.5 - 58.7), respectively. Participants aged 15 - 19 years had slightly inferior coverage to the 20 - 24-year-old group: 57.5% knew their status, 46.1% were on ART and 59.5% were virally suppressed, compared with 62.3%, 52.2% and 63.3%.Conclusions. These findings emphasise the need to close the gaps in HIV care coverage among AGYW, of whom only 61% knew their HIV-positive status and only 62% were virally suppressed. There is pro-poor inequality in HIV care coverage, with those in lower socioeconomic groups more likely to be virally suppressed