130 research outputs found
Pushing the boundaries : Virgilia oroboides (Keurboom) facilitated expansion of forest in to fynbos
The boundary between forest and fynbos vegetation in the Southern Cape of South Africa present a dynamic ecotone in which forest has previously been noted to have expanded into fynbos territory. Forest colonization of fynbos has been shown to be primarily a function of nutrients and light environments in the understory which may or may not be conducive for the growth of forest species. Additionally, it is understood that fire regime is the primary agent in determining forest/fynbos boundaries. Virgilia oroboides is a fast-growing leguminous tree confined to the margin between forest and fynbos. It has long been thought to facilitate the growth of forest species through the heavy shading and nutrient enrichment of soils; both of which facilitate the growth of forest seedlings. Furthermore, V. oroboides is predicted to reduce fuel loads and as a result prevent fire penetration of forests. These possible functions were tested by sampling soils, nutrient content of leaves and the shade cast by plants 18 months after a burn on a forest margin near Swellendam, Southern Cape. In addition, the effects of varying density of Virgilia on surrogates for fuel biomass, and forest seedling growth, were observed at Silvermine on the Cape Peninsula. Shaded environments produced by V. oroboides are shown to have detrimental effects on the growth of fynbos, while facilitating the growth of forests. V. oroboides had the highest soil nutrient enrichment potential of all species investigated and is therefore predicted to produce nutrient cycling processes conducive to the growth and regeneration of forests. Estimates of fuel in the understory of V. oroboides are predicted to reduce fynbos fire severity upon reaching the margin. These results suggest that Virgilia does indeed facilitate forest tree species more than light-demanding fynbos species so that its presence should result in greater stability or slow expansion of forests into fynbos. If supported by further work, this facilitative role of Virgilia has management implications for the conservation of fynbos and forests in the Southern Cape of South Africa
Pollinator-syndrome driven changes in the mating systems of two Cape legume species
The challenge in answering the question of whether or not plants evolve different mating systems to accommodate their respective pollinators lies in finding a pair of closely related species differing only in pollination syndromes. Furthermore, it has been hypothesized that Non-Flying Mammal Pollination (NFMP) arises from a bird pollinated ancestor as a result of their limited distributions. Liparia splendens subsp. splendens and L. parva are two genetically indistinguishable species that are thought to differ in pollination syndromes and co-occur with similar distributions, densities and have sympatric pollinators. Speculations that closely related sister species L. splendens subsp. splendens and L. parva are bird and nonflying mammal pollination (NFMP) respectively have been confirmed here. Furthermore, mating system divergence in terms of nectar volume and sugar concentration, pollen ovule rations and selfcompatibility has been investigated. There was no difference in nectar volume between the two species investigated, however, nectar concentrations have been found to be significantly higher in L. parva, which is thought to have evolved through selective pressures of pollinator preference. Similarly, pollen ovule ratios in L. parva (22663) are statistically higher than that of L. splendens subsp. splendens (17360), which is predicted to facilitate gene-flow between populations. Both species have been shown to have early-acting self-incompatible (ESI). Similar genetic variation and gene-flow of the two species in question suggest that NFMP is similar to that of bird pollination in its ability to maintain high levels of genetic diversity. The case of Liparia provides a basis to reject the hypothesis of NFMP evolution from a matrix of bird pollinated ancestors due to similar pollinator efficiencies
Accurate laboratory wavelengths of the e 3 Σ–(ν' = 5) – X 1 Σ+(ν'' = 0) band of 12C16O
CITATION: Dickenson, G. D. et al. 2010. Accurate laboratory wavelengths of the e 3 Σ–(ν' = 5) – X 1 Σ+(ν'' = 0) band of 12C16O. Astrophysical Journal Letters, 714(2):L268–L270, doi:10.1088/2041-8205/714/2/L268.The original publication is available at https://iopscience.iop.org/journal/2041-8205The forbidden singlet-triplet transitions of carbon monoxide (CO) are important in the interpretation of vacuum ultraviolet interstellar absorption spectra and in particular for the measurement of large CO column densities. Twenty rovibronic lines of the e 3Σ–(ν' = 5) – X 1Σ+(ν'' = 0) band of 12 C 16O for which laboratory wavelengths were previously unavailable were identified in laser-induced fluorescence excitation spectra. Wavelengths were assigned to five rovibronic transitions to an average accuracy of 0.0028 Å. A further 15 lines could not be fully resolved and average wavelengths were measured for these groups of closely spaced lines. A wavelength difference of 0.011 ± 0.0028 Å between the measured wavelengths and the calculated wavelengths in the atlas of Eidelsberg & Rostas demonstrates the need for more experimental data on CO.https://iopscience.iop.org/article/10.1088/2041-8205/714/2/L268Publisher's versio
Fast modularisation and aomic decomposition of ontologies using axiom dependency hypergraphs
In this paper we define the notion of an axiom dependency hypergraph, which explicitly represents how axioms are included into a module by the algorithm for computing locality-based modules. A locality-based module of an ontology corresponds to a set of connected nodes in the hypergraph, and atoms of an ontology to strongly connected components. Collapsing the strongly connected components into single nodes yields a condensed hypergraph that comprises a representation of the atomic decomposition of the ontology. To speed up the condensation of the hypergraph, we first reduce its size by collapsing the strongly connected components of its graph fragment employing a linear time graph algorithm. This approach helps to significantly reduce the time needed for computing the atomic decomposition of an ontology. We provide an experimental evaluation for computing the atomic decomposition of large biomedical ontologies. We also demonstrate a significant improvement in the time needed to extract locality-based modules from an axiom dependency hypergraph and its condensed version
Drastic reduction of orthopaedic services at an urban tertiary hospital in South Africa during COVID-19: Lessons for the future response to the pandemic
Background. The COVID-19 pandemic has impacted on the global surgery landscape.Objectives. To analyse and describe the initial impact of the COVID-19 pandemic on orthopaedic surgery at Groote Schuur Hospital, a tertiary academic hospital in South Africa.Methods. The number of orthopaedic surgical cases, emergency theatre patient waiting times, and numbers of outpatient clinic visits, ward admissions, bed occupancies and total inpatient days for January - April 2019 (pre-COVID-19) were compared with the same time frame in 2020 (COVID-19). The COVID-19 timeframe included initiation of a national ‘hard lockdown’ from 26 March 2020, in preparation for an increasing volume of COVID-19 cases.Results. April 2020, the time of the imposed hard lockdown, was the most affected month, although the number of surgical cases had started to decrease slowly during the 3 preceding months. The total number of surgeries, outpatient visits and ward admissions decreased significantly during April 2020 (55.2%, 69.1% and 60.6%, respectively) compared with April 2019 (p<0.05). Trauma cases were reduced by 40% in April 2020. Overall emergency theatre patient waiting time was 30% lower for April 2020 compared with 2019.Conclusions. COVID-19 and the associated lockdown has heavily impacted on both orthopaedic inpatient and outpatient services. Lockdown led to a larger reduction in the orthopaedic trauma burden than in international centres, but the overall reduction in surgeries, outpatient visits and hospital admissions was less. This lesser reduction was probably due to local factors, but also to a conscious decision to avoid total collapse of our surgical services
Low 30-day mortality in South African orthopaedic patients undergoing surgery at an academic hospital during the first wave of the COVID-19 pandemic: It was safe to perform orthopaedic procedures at our hospital during the first COVID-19 peak
Background. Initial local and global evidence suggests that SARS-CoV-2-infected patients who undergo surgery, and those who become infected perioperatively, have an increased mortality risk post surgery.Objectives. To analyse and describe the 30-day mortality, presurgical COVID-19 status and hospital-acquired SARS-CoV-2 infection rates of patients, both SARS-CoV-2-positive and negative, undergoing orthopaedic surgery at a tertiary academic hospital in South Africa (SA) during the first COVID-19 peak.Methods. This single-centre, observational, prospective study included patients who underwent orthopaedic procedures from 1 April 2020 (beginning of the COVID-19 case increase in SA) to 31 July 2020 (first COVID-19 peak in SA). All patients were screened for COVID-19 and were confirmed positive if they had a positive laboratory quantitative polymerase chain reaction test for SARS-CoV-2 RNA on a nasopharyngeal or oral swab. Thirty-day mortality, presurgical COVID-19 status and hospital-acquired SARS-CoV-2 infection were assessed.Results. Overall, a total of 433 operations were performed on 346 patients during the timeframe. Of these patients, 65.9% (n=228) were male and 34.1% (n=118) were female. The mean (standard deviation) age was 42.5 (16.8) years (range 9 - 89). Of the patients, 5 (1.4%) were identified as COVID-19 patients under investigation (PUI) on admission and tested positive for SARS-CoV-2 before surgery, and 1 (0.3%) contracted SARS-CoV-2 perioperatively; all survived 30 days post surgery. Twenty-nine patients were lost to follow-up, and data were missing for 6 patients. The final analysis was performed excluding these 35 patients. Of the 311 patients included in the final 30-day mortality analysis, 303 (97%) had a follow-up observation ≥30 days after the operation. The overall 30-day mortality for these patients was 2.5% (n=8 deaths). None of the recorded deaths were of screened COVID-19 PUI.Conclusions. We report a low 30-day mortality rate of 2.5% (n=8) for patients undergoing orthopaedic surgery at our hospital during the first COVID-19 peak. None of the deaths were COVID-19 related, and all patients who tested SARS-CoV-2-positive, before or after surgery, survived. Our overall 30-day mortality rate correlates with several other reports of orthopaedic centres analysing over similar timeframes during the first peak of the COVID-19 pandemic. Regarding mortality and SARS-CoV-2 infection risk, we can conclude that with the appropriate measures taken, it was safe to undergo orthopaedic procedures at our hospital during the first peak of the COVID-19 pandemic in SA
Rare Bilateral Nasopalatine Duct Cysts: A Case Report
The nasopalatine duct cyst (NPDC) is the most common of the non-odontogenic cyst of the jaws. This cysts are usually central or unilateral with no prevalence of side occurrence. The NPDC is the most frequent developmental, nonodontogenic cyst of the jaws. This cyst originates from epithelial remnants from the nasopalatine duct. The cells could be activated spontaneously during life, or are eventually stimulated by the irritating action of various agents (infection, etc.). Generally, patients present without clinical signs and symptoms. Therefore, the tentative diagnosis "nasopalatine duct cyst" is often based on a coincidental radiological finding on a routine panoramic view or occlusal radiograph. The definite diagnosis should be based on clinical, radiological and above all histopathologic findings. The therapy of nasopalatine duct cysts consists of an enucleation of the cystic tissue, only in rare cases a marsupialization needs to be performed. This report describes the appearance and treatment of a rare case of bilateral nasopalatine duct cyst
An endometrial histomorphometric study of CD56+ natural killer cells in women with unexplained infertility
BACKGROUND. The number of peripheral blood and endometrial natural killer cells varies greatly during implantation and the first trimester of
pregnancy and is thought to play a role in the maintenance of a healthy pregnancy. However, the role of endometrial CD56+ natural killer (NK)
cells as an immunological mechanism in unexplained infertility is yet unknown.
OBJECTIVES. The study aimed to enumerate the concentrations of CD56+ NK cells in endometrial samples, and to statistically compare these
numbers between fertile and infertile women.
METHODS. A histomorphometric analysis was conducted using haematoxylin and eosin staining and an immunohistochemical approach was used
for quantifying cell numbers.
RESULTS. Fifty samples were collected in equal parts between a study group of infertile female subjects (mean (standard deviation) age 35 (4), range
26 - 42 years) and a control group of multiparous fertile individuals (mean (SD) age 43.4 (6.3), range 30 - 55). The mean number of CD56+ NK cells
present at different depths for both the study and control groups did not differ significantly. Age and group (study or control) were not significantly
related to the mean number of CD56+ NK cells. However, for the late secretory phase the mean number of CD56+ NK cells was significantly higher
than for the early phase.
CONCLUSION. Our findings could not identify a statistically significant correlation between the number of CD56+ NK cells and infertility.Discovery Foundation Research Awardshttp://sajog.org.za/index.php/SAJOGhttp://www.journals.co.za/content/journalam2017Anatomical PathologyAnatomyHaematologyImmunologyStatistic
A multicentric study on stigma towards people with mental illness in health sciences students
BackgroundThere is evidence of negative attitudes among health professionals towards people with mental illness but there is also a knowledge gap on what training must be given to these health professionals during their education. The purpose of this study is to compare the attitudes of students of health sciences: nursing, medical, occupational therapy, and psychology.MethodsA comparative and cross-sectional study in which 927 final-year students from health sciences university programmes were evaluated using the Mental Illness: Clinicians' Attitudes (both MICA-2 and MICA-4) scale. The sample was taken in six universities from Chile and Spain.ResultsWe found consistent results indicating that stigma varies across university programmes. Medical and nursing students showed more negative attitudes than psychology and occupational therapy students in several stigma-related themes: recovery, dangerousness, uncomfortability, disclosure, and discriminatory behaviour.ConclusionsOur study presents a relevant description of the attitudes of each university programme for education against stigma in the formative years. Results show that the biomedical understanding of mental disorders can have negative effects on attitudes, and that education based on the psychosocial model allows a more holistic view of the person over the diagnosis
The utility of high-flow nasal oxygen for severe COVID-19 pneumonia in a resource-constrained setting: A multi-centre prospective observational study.
BACKGROUND: The utility of heated and humidified high-flow nasal oxygen (HFNO) for severe COVID-19-related hypoxaemic respiratory failure (HRF), particularly in settings with limited access to intensive care unit (ICU) resources, remains unclear, and predictors of outcome have been poorly studied. METHODS: We included consecutive patients with COVID-19-related HRF treated with HFNO at two tertiary hospitals in Cape Town, South Africa. The primary outcome was the proportion of patients who were successfully weaned from HFNO, whilst failure comprised intubation or death on HFNO. FINDINGS: The median (IQR) arterial oxygen partial pressure to fraction inspired oxygen ratio (PaO2/FiO2) was 68 (54-92) in 293 enroled patients. Of these, 137/293 (47%) of patients [PaO2/FiO2 76 (63-93)] were successfully weaned from HFNO. The median duration of HFNO was 6 (3-9) in those successfully treated versus 2 (1-5) days in those who failed (p<0.001). A higher ratio of oxygen saturation/FiO2 to respiratory rate within 6 h (ROX-6 score) after HFNO commencement was associated with HFNO success (ROX-6; AHR 0.43, 0.31-0.60), as was use of steroids (AHR 0.35, 95%CI 0.19-0.64). A ROX-6 score of ≥3.7 was 80% predictive of successful weaning whilst ROX-6 ≤ 2.2 was 74% predictive of failure. In total, 139 patents (52%) survived to hospital discharge, whilst mortality amongst HFNO failures with outcomes was 129/140 (92%). INTERPRETATION: In a resource-constrained setting, HFNO for severe COVID-19 HRF is feasible and more almost half of those who receive it can be successfully weaned without the need for mechanical ventilation
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