Computation of Burgers vectors from elastic strain and lattice rotation data.

A theoretical framework for computation of Burgers vectors from strain and lattice rotation data in materials with low dislocation density is presented, as well as implementation into a computer program to automate the process. The efficacy of the method is verified using simulated data of dislocations with known results. A three-dimensional dataset retrieved from Bragg coherent diffraction imaging (BCDI) and a two-dimensional dataset from high-resolution transmission Kikuchi diffraction (HR-TKD) are used as inputs to demonstrate the reliable identification of dislocation positions and accurate determination of Burgers vectors from experimental data. For BCDI data, the results found using our approach show very close agreement to those expected from empirical methods. For the HR-TKD data, the predicted dislocation position and the computed Burgers vector showed fair agreement with the expected result, which is promising considering the substantial experimental uncertainties in this dataset. The method reported in this paper provides a general and robust framework for determining dislocation position and associated Burgers vector, and can be readily applied to data from different experimental techniques.

A novel approach for engineering efficient nanofluids by radiolysis.

This contribution reports for the first time the possibility of using radiolysis to engineer stable efficient nanofluids which exhibit an enhanced thermal conductivity. The validation was confirmed on Ag-H2O and Ag-C2H6O2 nanofluids fabricated via g-radiolysis within the mild dose range of 0.95 × 103-2.45 × 103 Gray. The enhanced thermal conductivity of Ag-H2O and Ag-C2H6O2 nanofluids, was found to be g-radiations dose dependent. In the latter case of Ag-C2H6O2 nanofluid, the relative enhancement in the temperature range of 25-50 °C was found to be 8.89%, 11.54%, 18.69%, 23.57% and 18.45% for D1 = 0.95 × 103 Gray, D2 = 1.2 × 103 Gray, D3 = 1.54 × 103 Gray, D4 = 1.80 × 103 Gray and D5 = 2.45 × 103 Gray respectively. Yet not optimized, an enhancement of the effective thermal conductivity as much as 23.57% relatively to pure C2H6O2 was observed in stable Ag-C2H6O2 nanofluids. Equivalent results were obtained with Ag-H2O.

Decreased severity of disease during the first global omicron variant covid-19 outbreak in a large hospital in tshwane, south africa.

INTRODUCTION: The coronavirus disease 2019 (COVID-19) first reported in Wuhan, China in December 2019 is a global pandemic that is threatening the health and wellbeing of people worldwide. To date there have been more than 274 million reported cases and 5.3 million deaths. The Omicron variant first documented in the City of Tshwane, Gauteng Province, South Africa on 9 November 2021 led to exponential increases in cases and a sharp rise in hospital admissions. The clinical profile of patients admitted at a large hospital in Tshwane is compared with previous waves. METHODS: 466 hospital COVID-19 admissions since 14 November 2021 were compared to 3962 admissions since 4 May 2020, prior to the Omicron outbreak. Ninety-eight patient records at peak bed occupancy during the outbreak were reviewed for primary indication for admission, clinical severity, oxygen supplementation level, vaccination and prior COVID-19 infection. Provincial and city-wide daily cases and reported deaths, hospital admissions and excess deaths data were sourced from the National Institute for Communicable Diseases, the National Department of Health and the South African Medical Research Council. RESULTS: For the Omicron and previous waves, deaths and ICU admissions were 4.5% vs 21.3% (p<0.00001), and 1% vs 4.3% (p<0.00001) respectively; length of stay was 4.0 days vs 8.8 days; and mean age was 39 years vs 49,8 years. Admissions in the Omicron wave peaked and declined rapidly with peak bed occupancy at 51% of the highest previous peak during the Delta wave. Sixty two (63%) patients in COVID-19 wards had incidental COVID-19 following a positive SARS-CoV-2 PCR test . Only one third (36) had COVID-19 pneumonia, of which 72% had mild to moderate disease. The remaining 28% required high care or ICU admission. Fewer than half (45%) of patients in COVID-19 wards required oxygen supplementation compared to 99.5% in the first wave. The death rate in the face of an exponential increase in cases during the Omicron wave at the city and provincial levels shows a decoupling of cases and deaths compared to previous waves, corroborating the clinical findings of decreased severity of disease seen in patients admitted to the Steve Biko Academic Hospital. CONCLUSION: There was decreased severity of COVID-19 disease in the Omicron-driven fourth wave in the City of Tshwane, its first global epicentre.

Breed effects and heterosis for weight traits and tick count in a cross between an indigenous fat-tailed and a commercial sheep breed.

Ticks can compromise productivity and welfare in free-ranging sheep. Chemical tick control may not be sustainable in the long term. Alternative control measures must be sought for an integrated control programme. Birth and weaning weights as well as log transformed overall tick count of indigenous fat-tailed Namaqua Afrikaner (NA), commercial Dorper and NA x Dorper cross lambs were studied under extensive conditions. Relative to NA lambs, Dorper lambs were 22.2% heavier at weaning (P < 0.05). Geometric means for total tick count on Dorper lambs exceeded those of their Namaqua Afrikaner contemporaries by more than twofold (P < 0.05). Relative to the pure-breed midparent value, the mean performance of NA x Dorper lambs was 7.9% more for birth weight, 11.2% more for weaning weight and 26.2% less for the back transformed means for total tick count (P < 0.05). Heterosis for total tick count was slightly greater at -29.3% when data were adjusted for the larger size of NA x Dorper lambs. Crossing commercial Dorper sheep with a hardy, indigenous breed therefore resulted in lower levels of tick infestation without compromising live weight in progeny so derived. Hardy, indigenous genetic resources like the NA should be conserved and used in further studies of ovine genetics of resistance to ticks in South Africa.

Cultural consensus modelling to understand the reproductive health needs of South African adolescent girls.

BACKGROUND: Cultural consensus modelling (CCM) is an approach whereby individuals define the boundaries regarding a set of knowledge or behaviours shared by a group within a culture using an ethnographic approach. OBJECTIVES: To provide an overview of CCM methods and the application of CCM to examine South African adolescent girls' contraceptive and HIV prevention practices. METHODS: In phase 1 of a CCM approach, individuals respond to questions about their culture rather than their individual behaviours, allowing individuals to draw upon a shared cultural knowledge. Utilising these identified group beliefs, phase 2 asks individuals to rate the extent to which factors identified in phase 1 are valued. Phase 3 utilises qualitative interviews with key informants from phase 2 to gather in-depth information regarding the identified determinants of the health behaviour. Lastly, phase 4 of this approach conducts a quantitative survey to determine the extent to which cultural consensus model types are associated with differences in actual behaviours. RESULTS: CCM data analytic approaches are described. Frequencies and descriptive statistics for the free listing are conducted. For phase 2, cultural consensus analysis is conducted to examine whether one or several consensus models exist and competence scores are calculated. Standard qualitative analysis approaches are utilised for phase 3. Phase 4 employs regression to examine the association between cultural models and an outcome of interest. CONCLUSION: CCM provides a novel, culturally sensitive understanding of reproductive health practices among South African adolescent girls; CCM also has broad applicability to other adolescent health research domains.

Cultural consensus modelling to understand the reproductive health needs of South African adolescent girls

Background. Cultural consensus modelling (CCM) is an approach whereby individuals define the boundaries regarding a set of knowledge or behaviours shared by a group within a culture using an ethnographic approach. Objectives. To provide an overview of CCM methods and the application of CCM to examine South African adolescent girls' contraceptive and HIV prevention practices. Methods. In phase 1 of a CCM approach, individuals respond to questions about their culture rather than their individual behaviours, allowing individuals to draw upon a shared cultural knowledge. Utilising these identified group beliefs, phase 2 asks individuals to rate the extent to which factors identified in phase 1 are valued. Phase 3 utilises qualitative interviews with key informants from phase 2 to gather in-depth information regarding the identified determinants of the health behaviour. Lastly, phase 4 of this approach conducts a quantitative survey to determine the extent to which cultural consensus model types are associated with differences in actual behaviours. Results. CCM data analytic approaches are described. Frequencies and descriptive statistics for the free listing are conducted. For phase 2, cultural consensus analysis is conducted to examine whether one or several consensus models exist and competence scores are calculated. Standard qualitative analysis approaches are utilised for phase 3. Phase 4 employs regression to examine the association between cultural models and an outcome of interest. Conclusion. CCM provides a novel, culturally sensitive understanding of reproductive health practices among South African adolescent girls; CCM also has broad applicability to other adolescent health research domains

Genetic parameters for tick count and udder health in commercial and indigenous ewes in South Africa.

The genetics of tick infestation in sheep need study, as host resistance often forms part of integrated pest control programs. Repeated udder health scores, site-specific tick count, mating weight and reproduction records (N=879-1204) were recorded annually from 2010 to 2015 on ewes of the indigenous Namaqua Afrikaner (NA) fat-tailed breed, as well as the commercial Dorper and SA Mutton Merino (SAMM) breeds. Udders were scored subjectively on a 1-5 scale (1 - udder intact and 5 - udder damaged severely) and ticks were counted on three locations. The body sites counted were the head and thoracic limb (HTLTC), udder-pelvic limb (UPLTC) and perineum-breech-tail (PBTTC). These counts were also totaled for a total tick count (TTC). Reproduction traits were number of lambs weaned per ewe lambed and total weight of lamb weaned per ewe lambed. Udder health scores of NA ewes were lower than those of Dorpers, which in turn had lower scores than SAMM ewes. NA ewes had lower values for HTLTC, UPLTC and TTC than the commercial breeds, but higher values for PBTTC than Dorpers. Heritability estimates amounted to 0.26±0.04 for HTLTC, 0.53±0.04 for UPLTC, 0.07±0.06 for PBTTC, 0.44±0.06 for TTC and 0.61±0.03 for udder health score. Animal permanent environment also affected PBTTC (0.14±0.07). Significant genetic correlations were found between the HTLTC and UPLTC (0.47±0.10), UPLTC and udder health score (0.52±0.07), HTLTC and UPLTC (0.24±0.11) as well as UPLTC and PBTTC (-0.44±0.11). Heavier ewes had higher UPLTC (0.38±0.09), TTC (0.33±0.09) and impaired udder health (0.21±0.08). Udder health scores and tick counts at all sites were not related to reproduction traits. The indigenous NA breed outperformed the commercial breeds with lower values for HTLTC, UPLTC, TTC and a better udder health score. Mechanisms contributing to the better performance of the NA breed under pastoral conditions and the scope for selection for tick tolerance within breeds should be studied further.

System dynamic modelling to assess economic viability and risk trade-offs for ecological restoration in South Africa.

Can markets assist by providing support for ecological restoration, and if so, under what conditions? The first step in addressing this question is to develop a consistent methodology for economic evaluation of ecological restoration projects. A risk analysis process was followed in which a system dynamics model was constructed for eight diverse case study sites where ecological restoration is currently being pursued. Restoration costs vary across each of these sites, as do the benefits associated with restored ecosystem functioning. The system dynamics model simulates the ecological, hydrological and economic benefits of ecological restoration and informs a portfolio mapping exercise where payoffs are matched against the likelihood of success of a project, as well as a number of other factors (such as project costs and risk measures). This is the first known application that couples ecological restoration with system dynamics and portfolio mapping. The results suggest an approach that is able to move beyond traditional indicators of project success, since the effect of discounting is virtually eliminated. We conclude that systems dynamic modelling with portfolio mapping can guide decisions on when markets for restoration activities may be feasible.

A comparison between slaughter traits and meat quality of various sheep breeds: wool, dual-purpose and mutton.

The slaughter and meat quality traits of 20-month-old wool (Merino), dual-purpose (Dohne Merino and South African Mutton Merino [SAMM]) and mutton (Dormer) type sheep were compared. Average live weights of SAMM and Dormer sheep were 23% heavier than those of Dohne Merinos which were 28% heavier than Merinos. Fat depths at the thirteenth rib and lumbar regions of Merino and Dohne Merino sheep were lower than those of SAMM and Dormer sheep. The cooking loss, drip loss and shearing value from the M. longissimus dorsi did not differ between breeds. The initial juiciness and sustained juiciness of meat from Merinos were rated significantly lower by sensory analysis. Meat from Dohne Merino was rated significantly more tender for the attribute first bite. It was demonstrated that Dormer and SAMM sheep had heavier but fatter carcasses than Merinos and Dohne Merinos, with differences in meat quality between breeds.

Infestation with the sheep body louse (Bovicola ovis) in Merino lines divergently selected for maternal multiple rearing ability.

Data were obtained from a population consisting of 160 Merino ewes, as well as 64 male and 75 female progeny of these ewes at the 2-tooth age. The age and sex groups were maintained in separate flocks. The population has been divergently selected from the same base since 1986, either for (high or H line) or against (low or L line) maternal multiple rearing ability. All animals were inspected for sheep lice (Bovicola ovis) during September/October 2002 after a wool growth period of at least 4 months. When expressed relative to mean L-line performance, the advantage in lambs weaned per ewe during the lambing season amounted to approximately 110% in the H line (1.01 vs 0.48; P < 0.01). The proportion of animals on which 1 or more lice were observed were markedly lower in 2-tooth replacement ewes than in replacement rams and mature breeding ewes (0.053 vs 0.625 and 0.531, respectively; P < 0.01). One or more lice were observed on a lower proportion of H-line ewes than on those of the L line (0.413 vs 0.571, respectively; P < 0.10), while a similar tendency was observed in 2-tooth ewe hoggets (0.033 vs 0.143, respectively; P = 0.16). When the mean number of lice on individuals on which 1 or more lice were observed was compared between lines, the average number of lice observed on H-line young rams was lower than in the L line (4.36 +/- 0.85 vs 9.71 +/- 1.84 lice, respectively; P < 0.01). A similar tendency was observed in mature breeding ewes (2.15 +/- 0.38 vs 3.22 +/- 0.42 lice, respectively; P < 0.20). The more highly reproductive H-line ewes were not more susceptible to infestation with B. ovis than ewes of the L line. In fact, available evidence suggest that H-line animals could be more tolerant of B. ovis than those of the L line.