The electronic structure of the Nax_xCoO2_2 surface

The idea that surface effects may play an important role in suppressing $e_g'$ Fermi surface pockets on Na$_x$CoO$_2$ $(0.333 \le x \le 0.75)$ has been frequently proposed to explain the discrepancy between LDA calculations (performed on the bulk compound) which find $e_g$' hole pockets present and ARPES experiments, which do not observe the hole pockets. Since ARPES is a surface sensitive technique it is important to investigate the effects that surface formation will have on the electronic structure of Na$_{1/3}$CoO$_2$ in order to more accurately compare theory and experiment. We have calculated the band structure and Fermi surface of cleaved Na$_{1/3}$CoO$_2$ and determined that the surface non-trivially affects the fermiology in comparison to the bulk. Additionally, we examine the likelihood of possible hydroxyl cotamination and surface termination. Our results show that a combination of surface formation and contamination effects could resolve the ongoing controversy between ARPES experiments and theory.Comment: 4 pages, 2 figure

The burden of hypertension in KwaZulu-Natal Province, South Africa: A 6-year perspective

Background. Hypertension (HPT) and its complications continue to pose a global threat and contribute to premature mortality worldwide. The adverse interactions between HPT, obesity and COVID-19 are currently being witnessed globally and represent a collision of pandemics. Understanding the burden that this non-communicable disease (NCD) poses in KwaZulu-Natal (KZN) Province, South Africa (SA), would help in developing improved public healthcare strategies.Objectives. To describe the burden of HPT in all the districts of KZN over a 6-year period.Methods. HPT data are routinely collected from all KZN public health facilities (both clinics and hospitals) as part of the District Health Information System (DHIS). In this retrospective study, we accessed HPT records from the DHIS over a period of 6 years (2014 - 2019, inclusive). Data collected included the number of patients screened, diagnosed and initiated on therapy for HPT, together with the number of obese patients.Results. The slopes for HPT screening were positive at both clinics and hospitals in KZN (considerably more at clinics than hospitals, with a difference in elevations of slopes of p<0.001), with a significantly greater percentage of the population having been screened at rural clinics than at hospitals (difference in elevation of slopes p<0.001). A significantly greater number of patients aged <40 years (p<0.001) were being screened for HPT at clinics than at hospitals (2017/18, 2018/19, 2019/20), while hospitals screened considerably more patients aged ≥40 years in 2017 - 2018 (p<0.001). The numbers of new hypertensives diagnosed and having treatment initiated were on an upward slope at both clinics and hospitals, with clinics having a greater elevation of slope than hospitals (p<0.001), irrespective of patient age. A significantly greater number of patients aged ≥40 years (p<0.05) were diagnosed with HPT at both clinics and hospitals in KZN (2017/18, 2018/19, 2019/20). KZN clinics remained the first port of call for known hypertensives throughout the study period. Obesity was prevalent at both clinic and hospital level, although figures were significantly higher at clinics. Over 80% of the obesity burden was carried by the rural clinics and hospitals.Conclusions. Screening, diagnosis, treatment initiation and chronic management of HPT occur mainly at rural clinic level. The SA government needs to heed these findings and redirect resources (staffing and equipment) to this level. The prevalence of obesity was highest at rural healthcare facilities (clinics more than hospitals). More needs to be done to combat the obesity pandemic if we are to win the battle against NCDs (HPT and diabetes mellitus). A significant number of patients aged <40 years are being screened for HPT, which bodes well for the province, as early diagnosis and treatment of HPT are vital to prevent complications

Genetic analysis reveals the complex structure of HIV-1 transmission within defined risk groups

We explored the epidemic history of HIV-1 subtype B in the United Kingdom using statistical methods that infer the population history of pathogens from sampled gene sequence data. Phylogenetic analysis of HIV-1 pol gene sequences from Britain showed at least six large transmission chains, indicating a genetically variable, but epidemiologically homogeneous, epidemic among men having sex with men. Through coalescent-based analysis we showed that these chains arose through separate introductions of subtype B strains into the United Kingdom in the early-to-mid 1980s. After an initial period of exponential growth, the rate of spread generally slowed in the early 1990s, which is more likely to correlate with behaviour change than with reduced infectiousness resulting from highly active antiretroviral therapy. Our results provide new insights into the complexity of HIV-1 epidemics that must be considered when developing HIV monitoring and prevention initiatives

The origin of a1g_{1g} and eg_g' orderings in Nax_xCoO2_2

It has often been suggested that correlation effects suppress the small e_g' Fermi surface pockets of NaxCoO_2 that are predicted by LDA, but absent in ARPES measurements. It appears that within the dynamical mean field theory (DMFT) the ARPES can be reproduced only if the on-site energy of the eg' complex is lower than that of the a1g complex at the one-electron level, prior to the addition of local correlation effects. Current estimates regarding the order of the two orbital complexes range from -200 meV to 315 meV in therms of the energy difference. In this work, we perform density functional theory calculations of this one-electron splitting \Delta= \epsilon_a1g-\epsilon_e_g' for the full two-layer compound, Na2xCo2O4, accounting for the effects of Na ordering, interplanar interactions and octahedral distortion. We find that \epsilon a_1g-\epsilon e_g' is negative for all Na fillings and that this is primarily due to the strongly positive Coulomb field created by Na+ ions in the intercalant plane. This field disproportionately affects the a_1g orbital which protrudes farther upward from the Co plane than the e_g' orbitals. We discuss also the secondary effects of octahedral compression and multi-orbital filling on the value of \Delta as a function of Na content. Our results indicate that if the e_g' pockets are indeed suppressed that can only be due to nonlocal correlation effects beyond the standard DMFT.Comment: 4 pages, 3 figure

Genetic sequences derived from suppression subtractive hybridization analysis provides insight into their possible roles in Xanthomonas albilineans

Leaf scald disease (LSD) is caused by the Gram-negative bacterium, Xanthomonas albilineans. Genomic DNA from X. albilineans and Xanthomonas hyacinthi were analyzed by suppression subtractive hybridization (SSH) using X. albilineans as the tester from which unique sequences were sought and X. hyacinthi as the driver. Following the SSH procedure, amplification products within the size range of 100 - 600 bp were generated, purified, directly cloned with the Promega pGEM-T vector cloning kit, and transformed into ultracompetent Escherichia coli X L2-blue MRF’ cells (Stratagene, La Jolla, CA). Clones selected were sequenced (using a Perkin Elmer ABI PRISM Dye terminator cycle sequencing kit and ABI Model 377 DNA sequencer) in one direction with SP6 and T7 primers (Promega). Clone Xa 6 revealed very close homology with a probable bacterioferritin from Pseudomonasaeruginosa. Clone X. albilineans 12 showed 92% homology to the acetate repressor proteins and clone X. albilineans 18 displayed 85% homology to the plasmid pTOM9 from Alcaligenes xylosoxidans.Sequencing data also revealed homology to various hypothetical proteins

Speaking Truth to Power: A Personal Journey through the Politics of Boycott and Engagement at Rhodes University during the 1980s

No Abstrac

Towards a broader understanding of selection of students to train as health care professionals

Introduction: Institutes of Higher Learning (IHL) must train healthcare professionals (HCPs) able to meet priority needs of the population and address health system deficiencies. Concerns about the mismatch between outcome and policy have led many IHL to review their curriculum content. We argue for a broadening of selection criteria when choosing students to train as HCPs. Methods: A narrative inquiry drawing on life-history interviews and art-based methods was used to generate and collect data on lived lives as told and experienced by six rural-origin HCPs. Results: Analysis of two narrative vignettes framed as dilemmatic spaces show how personal beliefs and practices inform perspectives that HCPs adopted in their learning and development at IHL, and the transformational practices they enacted. Discussion: How competing forces were negotiated and positions were taken in committing to become HCPs with the capacity to lead transformation is described. Introducing and using dilemmatic spaces analytically enabled deeper understanding of beliefs and priorities that are important to consider alongside academic potential

Musculoskeletal pain in South African wheelchair basketball players of different point classifications

Background: During recent years, wheelchair basketball has gained worldwide popularity. Several studies have demonstrated a high prevalence of injuries amongst wheelchair basketball players. Few studies, however, have investigated the prevalence of musculoskeletal pain in the context of different point classifications – an integral part of wheelchair sport.Objective: The aim of this study was to determine the prevalence of musculoskeletal pain in wheelchair basketball players of different point classifications in South Africa and to provide information on patterns of pain distribution in relation to point classification.Methods: A questionnaire was completed by 48 wheelchair basketball players participating in the SuperSport League Games of South Africa with point classifications ranging from 1.0 to 4.5. The results were used to determine the patterns of musculoskeletal pain distribution in relation to the different point classifications.Results: Forty-three completed questionnaires were analysed. The prevalence of total musculoskeletal pain was 58% (n=25). Shoulder pain presented the highest overall prevalence, regardless of point classification (n=23; 92% since the start of players’ wheelchair basketball careers and n=19; 76% over the last 12 months). It was found that lower point classification (1.0-2.5) players commonly experienced arm pain since the start of their wheelchair basketball careers (ƞ=0.358), as well as specifically over the last 12 months (ƞ=0.319), unlike higher point classification (3.0-4.5) players.Discussion: The study contextualises the prevalence of musculoskeletal pain to overall point classification in wheelchair basketball. Such data are important in the formation of injury prevention strategies, as athletes with impairments are predisposed to different types of musculoskeletal pain based on point classification. Keywords: physical activity, athletes with impairments, prevalence, injury preventio

"The corporate university" training and learning solution for a South African airline industry.

The training and development of employees in the airline industry usually take place within a decentralized structure and may result in fragmented and costly initiatives. To improve the current practice a corporate university (CU) model to be implemented in the airline is proposed. For the purpose of the study qualitative interviews were held, human documents were studied and participant observation and the views of employees of the South African airline industry were sought regarding training in general and CUs in particular. The study revealed support for the CU concept because it would encourage continuous learning at all levels in the organisation and would place emphasis on both employee and organisational needs