Straight Line Orbits in Hamiltonian Flows

We investigate periodic straight-line orbits (SLO) in Hamiltonian force fields using both direct and inverse methods. A general theorem is proven for natural Hamiltonians quadratic in the momenta in arbitrary dimension and specialized to two and three dimension. Next we specialize to homogeneous potentials and their superpositions, including the familiar H\'enon-Heiles problem. It is shown that SLO's can exist for arbitrary finite superpositions of $N$-forms. The results are applied to a family of generalized H\'enon-Heiles potentials having discrete rotational symmetry. SLO's are also found for superpositions of these potentials.Comment: laTeX with 6 figure

A Panel of Ancestry Informative Markers for the Complex Five-Way Admixed South African Coloured Population

Admixture is a well known confounder in genetic association studies. If genome-wide data is not available, as would be the case for candidate gene studies, ancestry informative markers (AIMs) are required in order to adjust for admixture. The predominant population group in the Western Cape, South Africa, is the admixed group known as the South African Coloured (SAC). A small set of AIMs that is optimized to distinguish between the five source populations of this population (African San, African non-San, European, South Asian, and East Asian) will enable researchers to cost-effectively reduce false-positive findings resulting from ignoring admixture in genetic association studies of the population. Using genome-wide data to find SNPs with large allele frequency differences between the source populations of the SAC, as quantified by Rosenberg et. al's -statistic, we developed a panel of AIMs by experimenting with various selection strategies. Subsets of different sizes were evaluated by measuring the correlation between ancestry proportions estimated by each AIM subset with ancestry proportions estimated using genome-wide data. We show that a panel of 96 AIMs can be used to assess ancestry proportions and to adjust for the confounding effect of the complex five-way admixture that occurred in the South African Coloured population.Department of HE and Training approved lis

School-based human papillomavirus vaccination: An opportunity to increase knowledge about cervical cancer and improve uptake of screening

Background. Poor knowledge about cervical cancer plays a role in limiting screening uptake. HPV vaccination provides an untested platform to distribute information that could possibly improve knowledge and screening coverage.Objective. To measure changes in knowledge and screening uptake when information and screening opportunities were provided to mothers of adolescent HPV vaccine recipients.Methods. During an HPV vaccine implementation project in the Western Cape (WC) and Gauteng Province (GP), South Africa, information about cervical cancer was provided to parents during a lecture, written information was distributed, and mothers were then invited to either screen at their clinic (WC) or use a self-screening kit (GP). A structured questionnaire was used to test cervical cancer knowledge and screening practices, comparing these before and after the project and between the two screening groups.Results. Complete data for both questionnaires were available for 777 of 906 recruited women. Initial knowledge was poor, but on retesting 6 months later, knowledge about symptoms (p<0.005), screening (p<0.005) and vaccination (p<0.05) improved significantly after the information session and school-based HPV vaccination. In the second questionnaire, women reported significantly more screening and the last reported screening test was more recent. This improvement was more favourable in GP than in the WC (41% v. 26% reporting screening in the past 12 months).Conclusion. These results demonstrate how adolescent HPV vaccine programmes can help to control cervical cancer among mothers by offering information and screening. It is important not to lose this opportunity to educate mothers and their daughters and offer effective methods to prevent cervical cancer in both generations

Long-stay medical-surgical intensive care unit patients in South Africa : quality of life and mortality 1 year after discharge

BACKGROUND. Although mortality is the primary measure of critical care outcome, the health-related quality of life (HRQOL) of survivors is often diminished. There is a paucity of South African research on HRQOL in intensive care unit (ICU) survivors. OBJECTIVES. To evaluate the 1-year post-discharge data of long-stay ICU patients, a group known to consume 20 - 40% of ICU resources. METHODS. A 1-year prospective observational study was conducted in a multidisciplinary medical-surgical ICU. Adult patients who were mechanically ventilated beyond 6 days were included. Clinical and mortality data were collected. Pre-admission and 6- and 12-month HRQOL were measured with the Short Form-36 questionnaire. Physical and mental component summary scores (PCS and MCS) were calculated. Associations between 12-month mortality and poor HRQOL scores were determined. RESULTS. Of 119 patients enrolled, 40.3% had sustained trauma, 19.3% were post-surgical and 40.3% had medical conditions; 29.2% were HIV-positive (HIV status was known for 74.8% of the cohort). The hospital and 12-month mortality rates were 42.9% and 57.4% (n=66/115), respectively. Age, longer ICU stay, higher disease severity scores and vasopressor use were associated with 12-month mortality. The survivors’ median PCS and MCS at 6 and 12 months were significantly lower compared with pre-admission scores (both p<0.001). At 12 months, 53.1% of survivors demonstrated a poor PCS and 42.9% a poor MCS. Associations with poor 12-month PCS included longer ICU stay, male gender and trauma, while trauma and sepsis were associated with a poor 12-month MCS. Among the 19 trauma survivors, 78.9% had a poor MCS and/or PCS. Of previously employed patients, 54.8% were unemployed at 12 months. CONCLUSIONS. Patients ventilated beyond 6 days in a multidisciplinary ICU had a high mortality. Poor HRQOL at 12 months post discharge was frequently observed among survivors. Trauma was associated with poor 12-month outcomes. These findings highlight the need to further explore the outcomes of long-stay ICU patients in Africa.South African Critical Care Society research grant.http://www.samj.org.zadm2022Critical Car

Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure

ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries

This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of "big data" (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA's activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors

Evaluation of nutrition care to adult patients on HAART attending primary healthcare facilities in Mpumalanga

CITATION: Schiever, J. F. et al. 2019. Evaluation of nutrition care to adult patients on HAART attending primary healthcare facilities in Mpumalanga, South African Journal of Clinical Nutrition, 32(1):13-20. doi:10.1080/16070658.2017.1412183The original publication is available at https://www.tandfonline.com/toc/ojcn20/currentObjectives: This study aimed to evaluate nutrition care and nursing professional knowledge received by adults on highly active antiretroviral therapy attending primary health care (PHC) facilities Design: Cross-sectional, descriptive study. Subjects and setting: The study was conducted on 263 adults and 75 nursing professionals, recruited from 19 facilities in the Mbombela sub-district, Mpumalanga. Outcome measures: Interviewer-administered questionnaires were completed for each patient. Nursing professionals completed a self-administered questionnaire. Assessment tools were completed for each facility. Results: Some 41% of patients were either overweight or obese, and most females (n = 87; 51.8%) had a BMI ≥ 25 kg/m2. Based on waist circumference, 52.7% (n = 88) of females and 8.4% (n = 8) of males showed increased risk of cardiovascular disease. Although nurses were aware of a nutrition supplementation programme, knowledge of national nutrition guidelines was inadequate. Clinical judgement, rather than eligibility criteria, was used to identify suitable patients, with 13.3% (n = 35) receiving supplementation whereas only 4.9% (n = 13) qualified. Facilities generally had sufficient equipment and fair storage conditions, but stock shortages of nutrition supplements were problematic. Conclusions: Whilst certain positive findings emerged, nutrition care could be improved, largely through adequate training and support to professional nurses. Training should focus on correct execution of assessment measurements and appropriate nutritional counselling, emphasising balanced eating, food security and prevention of over-nutrition. Nurses should be familiarised with national nutrition guidelines and have access to a constant nutrition supplementation supply. Improved monitoring and evaluation of nutrition care to adults on treatment at PHC facilities is needed.https://www.tandfonline.com/doi/full/10.1080/16070658.2017.1412183Publisher’s versio

Associations between human leukocyte antigen class I variants and the Mycobacterium tuberculosis subtypes causing disease

BACKGROUND. The development of active tuberculosis disease has been shown to be multifactorial. Interactions between host and bacterial genotype may influence disease outcome, with some studies indicating the adaptation of M. tuberculosis strains to specific human populations. Here we investigate the role of the human leukocyte antigen (HLA) class I genes in this biological process. METHODS. Three hundred patients with tuberculosis from South Africa were typed for their HLA class I alleles by direct sequencing. Mycobacterium tuberculosis genotype classification was done by IS6110 restriction fragment length polymorphism genotyping and spoligotyping. RESULTS. We showed that Beijing strain occurred more frequently in individuals with multiple disease episodes (P < .001) with the HLA-B27 allele lowering the odds of having an additional episode (odds ratio, 0.21; P = .006). Associations were also identified for specific HLA types and disease caused by the Beijing, LAM, LCC, and Quebec strains. HLA types were also associated with disease caused by strains from the Euro-American or East Asian lineages, and the frequencies of these alleles in their sympatric human populations identified potential coevolutionary events between host and pathogen. CONCLUSIONS. This is the first report of the association of human HLA types and M. tuberculosis strain genotype, highlighting that both host and pathogen genetics need to be taken into consideration when studying tuberculosis disease development.Web of Scienc