A novel topology of high-speed SRM for high-performance traction applications

A novel topology of high-speed Switched Reluctance Machine (SRM) for high-performance traction applications is presented in this article. The target application, a Hybrid Electric Vehicle (HEV) in the sport segment poses very demanding specifications on the power and torque density of the electric traction machine. After evaluating multiple alternatives, the topology proposed is a 2-phase axial flux machine featuring both segmented twin rotors and a segmented stator core. Electromagnetic, thermal and mechanical models of the proposed topology are developed and subsequently integrated in an overall optimisation algorithm in order to find the optimal geometry for the application. Special focus is laid on the thermal management of the machine, due to the tough thermal conditions resulting from the high frequency, high current and highly saturated operation. Some experimental results are also included in order to validate the modelling and simulation results

Closed traction reduction of cervical spine facet dislocations: Compelled by law

Background. Following a 2015 ruling, the South African (SA) Constitutional Court obligates closed reduction of cervical facet dislocations sustained through low-energy injury mechanisms, within 4 hours of injury. Closed traction reduction of cervical facet dislocations requires specific equipment and expertise, which have limited availability in SA.Objectives. To review the time delays, delaying factors and success rate of closed reductions of cervical facet dislocations in a tertiary-level orthopaedic department and training facility, and to consider the feasibility of such a reduction within 4 hours after injury.Methods. The clinical records and imaging screens of patients presenting with cervical facet dislocations to an academic training hospital between November 2008 and March 2016 were retrospectively reviewed, with specific attention to demographic information, mechanism of injury, time delays from injury to treatment and factors resulting in delay, as well as the success rate in closed cervical reduction.Results. Ninety-one patients with cervical dislocation presented during the study period, of whom 69 were included for further review. The mean age at presentation was 37.6 (range 18 - 65) years. Successful reduction was achieved in 71% (n=49) of cases, with a median delay time from injury to reduction of 26 (interquartile range (IQR) 19.50 - 31.75) hours. Only 1 patient of 69 patients received successful reduction within 6 hours after injury. Neurological improvement was noticed in 5 of 53 patients with neurological deficit – after successful reduction. Two patients improved with two American Spinal Injury Association (ASIA) grades (from A to C), and 2 improved with one ASIA grade (from A to B and D to E).Conclusions. Successful reduction of a cervical facet dislocation within 4 hours presents a challenge to healthcare infrastructure globally. The relative scarcity of this type of injury (91 cases during 8 years in a tertiary referral hospital) prevents district-level clinicians from readily acquiring a level of experience to confidently perform closed reduction of these injuries, unless very specific training and support are provided towards this end

Survival of children in Cape Town known to be vertically infected with HIV-1

Objective. To determine the survival patterns of children in Cape Town known to be vertically infected with HIV.Design. Retrospective record review of children diagnosed with symptomatic HIV infection during the period 1 December 1990 - 31 May 1995.Setting. Hospitals in the Cape Town metropolitan area.Patients. 193 children were known to be vertically HIV infected. HIV diagnosis was based on the following criteria: two positive HIV enzyme-linked immunosorbent assays (ELlSAs) in children older than 15 months and a positive ELlSA together with a positive polymerase chain reaction (PCR) in younger children. The mothers of the children were known to be HIV-positive. On the basis of the presenting clinical findings children were assigned to a disease severity category (A, B or C) according to the Centers for Disease Control and Prevention (CDC)'s 1994 revised classification system for HIV infection in children.Outcome measures. Survival was analysed according to the Kaplan-Meier method. Survival time was defined as the length of time between clinical diagnosis of HIV and death or last contact with the health services. Mortality risk in relation to specific variables at diagnosis such as age and clinical manifestations was determined by calculation of odds ratios (ORs) with 95% confidence intervals (Cls).Results. The median age at diagnosis was 5 months; 72% of children were aged less than 1 year at diagnosis. According to the CDC clinical classification, 47 (24%) fell into category A, 111 (58%) into category Band 35 (18%) into category C. Of the 193 patients 85 (44%) were alive at the time of review, 65 (34%) had died and 43 (22%) were lost to folloW-Up. Risk of death was significantly associated with age less than 6 months (OR 4.7, Cl 2.1 - 10.3) and severe disease, Le. CDC category C (OR 2.7; Cl 1.1 - 6.9) at time of diagnosis. The median survival for all the children from time of diagnosis was 32 months. Infants diagnosed before 6 months of age had significantly shorter median survival (10 months) compared with 36 months for those diagnosed at 7 - 12 months of age. For the children over the age of 12 months the cumulative proportion surviving at 48 months was 78%. Children with severe disease (category C) had a median survival of 21 months, significantly lower than that in category B (32 months). For the children in category A the cumulative proportion surviving at 48 months was 66%.Conclusion. The median survival of children with HIV was 32 months from time of diagnosis, and survival was influenced by age and disease severity

Aeolianite and barrier dune construction spanning the last two glacial-interglacial cycles from the southern Cape coast, South Africa

The southern Cape region of South Africa has extensive coastal aeolianites and barrier dunes. Whilst previously reported, limited knowledge of their age has precluded an understanding of their relationship with the climatic and sea-level fluctuations that have taken place during the Late Quaternary. Sedimentological and geomorphological studies combined with an optical dating programme reveal aeolianite development and barrier dune construction spanning at least the last two glacial–interglacial cycles. Aeolianite deposition has occurred on the southern Cape coast at ca 67–80, 88–90, 104–128, 160–189 and >200 ka before the present. Using this and other published data coupled with a better understanding of Late Quaternary sea-level fluctuations and palaeocoastline configurations, it is concluded that these depositional phases appear to be controlled by interglacial and subsequent interstadial sea-level high stands. These marine transgressions and regressions allowed onshore carbonate-rich sediment movement and subsequent aeolian reworking to occur at similar points in the landscape on a number of occasions. The lack of carbonates in more recent dunes (Oxygen Isotope Stages 1/2 and 4/5) is attributed not to leaching but to changes to carbonate production in the sediment source area caused by increased terrigenous material and/or changes in the balance between the warm Agulhas and nutrient-rich Benguela ocean current

The Interstellar Environment of our Galaxy

We review the current knowledge and understanding of the interstellar medium of our galaxy. We first present each of the three basic constituents - ordinary matter, cosmic rays, and magnetic fields - of the interstellar medium, laying emphasis on their physical and chemical properties inferred from a broad range of observations. We then position the different interstellar constituents, both with respect to each other and with respect to stars, within the general galactic ecosystem.Comment: 39 pages, 12 figures (including 3 figures in 2 parts

TB Hackathon: Development and Comparison of Five Models to Predict Subnational Tuberculosis Prevalence in Pakistan

Pakistan’s national tuberculosis control programme (NTP) is among the many programmes worldwide that value the importance of subnational tuberculosis (TB) burden estimates to support disease control efforts, but do not have reliable estimates. A hackathon was thus organised to solicit the development and comparison of several models for small area estimation of TB. The TB hackathon was launched in April 2019. Participating teams were requested to produce district-level estimates of bacteriologically positive TB prevalence among adults (over 15 years of age) for 2018. The NTP provided case-based data from their 2010–2011 TB prevalence survey, along with data relating to TB screening, testing and treatment for the period between 2010–2011 and 2018. Five teams submitted district-level TB prevalence estimates, methodological details and programming code. Although the geographical distribution of TB prevalence varied considerably across models, we identified several districts with consistently low notification-to-prevalence ratios. The hackathon highlighted the challenges of generating granular spatiotemporal TB prevalence forecasts based on a cross-sectional prevalence survey data and other data sources. Nevertheless, it provided a range of approaches to subnational disease modelling. The NTP’s use and plans for these outputs shows that, limitations notwithstanding, they can be valuable for programme planning