27 research outputs found
A prospectus for sustainability of rainfed maize production systems in South Africa
CITATION: Haarhoff, S. J., Kotze, T. N. & Swanepoel, P. A. 2020. A prospectus for sustainability of rainfed maize production systems in South Africa. Crop Science, 60(1):14-28, doi:10.1002/csc2.20103.The original publication is available at https://acsess.onlinelibrary.wiley.comThe rainfed maize (Zea mays L.) production systems of South Africa require an integrated approach to use the limited soil available water more efficiently, and to increase system productivity and sustainability. The soils across the major maize production regions are highly susceptible to wind and water erosion. Rigorous soil tillage, maize monoculture, and fallow periods are common, which depletes the soil from organic matter and nutrients. Despite the pressing need for transforming the highly degraded rainfed maize production systems, adoption of more sustainable management approaches has been limited, likely due to a shortage of local scientific field trials to evaluate current and alternative maize agronomic management practices. Erratic interseasonal rainfall patterns cause high variability in maize grain yields. Major challenges associated with no‐tillage are poor crop establishment, subsoil compaction, and high maize grain yield variability. The use of fallow in the maize–fallow production system leads to excessive runoff and soil erosion losses despite increased maize grain yields. Crop intensification and alternative crops are needed to increase rainfall water use efficiency and lower fallow frequency. The use of cover and forage crops may provide the opportunity to diversify and intensify maize production systems. Cover crop biomass could be beneficial in livestock‐integrated production systems providing livestock feed in either winter or summer. Research is drastically required to improve the understanding of current South African rainfed maize production systems and to facilitate the development of fitting sustainable agronomic management practices.https://acsess.onlinelibrary.wiley.com/doi/10.1002/csc2.20103Publisher's versio
Sensitivity simulation and measurement of the SKA Band 1 wideband feed package on MeerKAT
Advances in wideband feed technology for radio telescopes enable high sensitivity observations over large bandwidths. The wideband quad-ridge flared horn (QRFH) feed package for Band 1 of the Square Kilometre Array (SKA) was optimized for high sensitivity. The 3:1 feed package covers 350-1050 MHz and is a complete room temperature system with low-noise amplifiers integrated inside the ridges of the horn. The QRFH is dual-linear polarized and designed with spline-defined profiles for the horn and ridge shape. Measured feed s-parameters show input reflection less than -11 dB across the band with good port isolation. In this paper we present the first measured sensitivity levels of the Band 1 feed package, which was tested on the SKA precursor reflector MeerKAT. We also present measured aperture efficiency and intrinsic cross-polarization (IXR). The measured results show good agreement with simulations
Finally seen : a rare sighting of Antarctic blue whale cow–calf pair off the west coast of South Africa
Blue whales are rarely sighted off the coasts of South Africa due to their low numbers and offshore habitat preference. Visual observations to search for marine mammals were conducted onboard a platform of opportunity during the Integrated Ecosystems Programme survey in November 2019. A cow–calf pair of blue whales Balaenoptera musculus was sighted offshore Kleinzee (30°05′02.4" S, 14°24′53.2" E) at a water depth of 1670 m on the west coast of South Africa in the southern Benguela Current System. The pair was identified as Antarctic blue whales B. m. intermedia based on the size of the cow (~ 29 m), “torpedo-shaped” body of the cow, known distribution ranges and recent acoustic data showing that pygmy blue whales B. m. brevicauda do not occur in these waters. The calf was likely born in the Benguela ecosystem given its relatively small size. This is the first sighting of Antarctic blue whale cow–calf pair in South African waters post whaling, indicating that animals might still use this area as a calving or nursing ground. Improved protection of this region in the low latitudes might benefit the recovery and conservation of the species.The Department of Forestry, Fisheries and the Environment.https://link.springer.com/journal/300hj2023Mammal Research Institut
The Dutch Reformed Church as a prominent established South African church: In transition towards the 21st century
The Dutch Reformed Church (Nederduitse Gereformeerde Kerk) is in transition because of the influences of the more recent South African epochs of democratisation, Africanisation and globalisation. The histories of these epochs extend over more than 20 years and have had a significant influence on the church. The Dutch Reformed (DR) Church changed institutionally because its place and influence within society changed considerably as a result of political and social transformation since 1994. The ongoing process of Africanisation that accompanies these transformations brings certain reactions to the bosom of the church via the experiences of its members. Most are Afrikaners being more inclined to westernised social frames of reference. Ironically, these people are more susceptible to the effects of globalisation, especially secularisation, which transposes the religious set-up of the DR Church into an open and individuated system. These developments pose major challenges to the DR Church in the sense that it has to reconsider how it approaches society, what it can contribute to the ecumenical church, why it is necessary to reflect on its denominational identity and what its academic, theological endeavours in these regards entail.Intradisciplinary and/or interdisciplinary implications: This article has an interdisciplinary scope because the multiplicity of the present-day calls for interdisciplinary academic reflection. For the purpose of this article, Church Historiography helps to systemise recent ecclesiastical developments within the DR Church. To clarify the influences of these developments on the DR Church, sociological premises are incorporated to describe them within a broader social context. References to the conducted empirical study serve to explain respondents� (members of the DR Church) social and religious constructs regarding these ecclesiastical and sociological phenomena.</p
Risk factors for Coronavirus disease 2019 (Covid-19) death in a population cohort study from the Western Cape province, South Africa
Risk factors for coronavirus disease 2019 (COVID-19) death in sub-Saharan Africa and the effects of human immunodeficiency virus (HIV) and tuberculosis on COVID-19 outcomes are unknown. We conducted a population cohort study using linked data from adults attending public-sector health facilities in the
Western Cape, South Africa. We used Cox proportional hazards models, adjusted for age, sex, location, and comorbidities, to examine the associations between HIV, tuberculosis, and COVID-19 death from 1 March to 9 June 2020 among (1) public-sector “active patients” (≥1 visit in the 3 years before March 2020); (2) laboratory-diagnosed COVID-19 cases; and (3) hospitalized COVID-19
cases. We calculated the standardized mortality ratio (SMR) for COVID-19, comparing adults living with and without HIV using
modeled population estimates.Among 3 460 932 patients (16% living with HIV), 22 308 were diagnosed with COVID-19, of whom 625 died. COVID19 death was associated with male sex, increasing age, diabetes, hypertension, and chronic kidney disease. HIV was associated with
COVID-19 mortality (adjusted hazard ratio [aHR], 2.14; 95% confidence interval [CI], 1.70–2.70), with similar risks across strata of
viral loads and immunosuppression. Current and previous diagnoses of tuberculosis were associated with COVID-19 death (aHR,
2.70 [95% CI, 1.81–4.04] and 1.51 [95% CI, 1.18–1.93], respectively). The SMR for COVID-19 death associated with HIV was 2.39
(95% CI, 1.96–2.86); population attributable fraction 8.5% (95% CI, 6.1–11.1)
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Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study
Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat
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Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study
The original version of this article unfortunately contained a mistake
Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study
Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat
Development of a QPSK demodulator for the Sunsat 1 groundstation
Thesis (MEng)--Stellenbosch University, 2000.ENGLISH ABSTRACT: The purpose of this thesis is the description of the development of a QPSK demodulator
for the Sunsat 1 groundstation. A general overview of the functioning and requirements
of a typical QPSK demodulator system is given. Several methods or algorithms for clock
and carrier recovery are discussed. Specific attention is given to the QPSK demodulator
chipset from Philips used for the implementation of the demodulator. The digital
decoding logic used to serialize the parallel I and Q datastream is explained. Finally
measurement techniques for performance evaluation of QPSK systems are investigated.
As part of this the implementation loss of the developed QPSK demodulator is measured.AFRIKAANSE OPSOMMING: Die doelwit van hierdie tesis is om die ontwikkeling van 'n QPSK demodulator vir die
Sunsat 1 grondstasie te beskryf. 'n Algemene oorsig oor die funksionering en vereistes van
'n tipiese QPSK demodulator stelsel word gegee. Verskeie algoritmes en tegnieke vir klok
en draersein herwinning word ondersoek en bespreek. Spesifieke verwysing word telkens
gemaak na die QPSK demodulasie vlokkie paar van Philips gebruik vir die implementering
van die demodulator. Die digitale dekodering logika benodig vir die datastroom
verpakking word ondersoek en beskryf. Laastens word daar gekyk na meettegnieke en
evaluasie van QPSK demodulasie stelsels se prestasie. As deel hiervan word die implementasie
verlies van die ontwikkelde QPSK demodulator stelsel gemeet
Low cost high benefit improvements to Ben Schoeman freeway
Paper presented at the South African Transport Conference 17 - 20 July 2000 "Action in transport for the new millennium", CSIR International Convention Centre, Pretoria, South Africa.This paper was transferred from the original CD ROM created for this conference. The material on the CD ROM was published using Adobe Acrobat technology. The original CD ROM was produced by Document Transformation Technologies Postal Address: PO Box 560 Irene 0062 South Africa. Tel.: +27 12 667 2074 Fax: +27 12 667 2766 E-mail: [email protected] URL: http://www.doctech.co.z