South African and Norwegian Prospective Teachers’ Critical Discussions About Mathematical Models Used in Society

2021 ◽  
pp. 501-511
Author(s):  
Suela Kacerja ◽  
Cyril Julie ◽  
Mohammad Faaiz Gierdien ◽  
Rune Herheim ◽  
Inger Elin Lilland ◽  
...  
Keyword(s):  
Mathematical Models ◽  
South African ◽  
Prospective Teachers

scholarly journals Age bias in survey sampling and implications for estimating HIV prevalence in men who have sex with men: insights from mathematical modelling

2018 ◽  
Vol 146 (8) ◽  
pp. 1036-1042 ◽  
Author(s):  
L. F. Johnson ◽  
P. Mulongeni ◽  
A. Marr ◽  
T. Lane
Keyword(s):  
Mathematical Models ◽  
South African ◽  
Hiv Prevalence ◽  
Age Bias ◽  
Agent Based ◽  
Adjusted Analysis ◽  
Younger Age ◽  
Age Profile ◽  
Sex With Men ◽  
Unadjusted Analysis

AbstractRespondent-driven sampling (RDS) is widely used to estimate HIV prevalence in men who have sex with men (MSM). Mathematical models that are calibrated to these data may be compromised if they fail to account for selection biases in RDS surveys. To quantify the potential extent of this bias, an agent-based model of HIV in South Africa was calibrated to HIV prevalence and sexual behaviour data from South African studies of MSM, first reweighting the modelled MSM population to match the younger age profile of the RDS surveys (age-adjusted analysis) and then without reweighting (unadjusted analysis). The model estimated a median HIV prevalence in South African MSM in 2015 of 34.6% (inter-quartile range (IQR): 31.4–37.2%) in the age-adjusted analysis, compared with 26.1% (IQR: 24.1–28.4%) in the unadjusted analysis. The median lifetime risk of acquiring HIV in exclusively homosexual men was 88% (IQR: 82–92%) in the age-adjusted analysis, compared with 76% (IQR: 64–85%) in the unadjusted analysis. These results suggest that RDS studies may under-estimate the exceptionally high HIV prevalence rates in South African MSM because of over-sampling of younger MSM. Mathematical models that are calibrated to these data need to control for likely over-sampling of younger MSM.

Prospective Teachers' Use of Computing Tools to Develop and Validate Functions as Mathematical Models

1998 ◽  
Vol 29 (2) ◽  
pp. 184-201
Author(s):  
Rose Mary Zbiek
Keyword(s):  
Secondary School ◽  
Mathematical Models ◽  
Mathematics Teachers ◽  
Prospective Teachers ◽  
Real World ◽  
Technology Use ◽  
Strategy Choice ◽  
Task Characteristics ◽  
Strategy Selection ◽  
Continuous Access

This study explored the strategies used by 13 prospective secondary school mathematics teachers to develop and validate functions as mathematical models of real-world situations. The students, enrolled in an elective mathematics course, had continuous access to curve fitters, graphing utilities, and other computing tools. The modeling approaches fell under 4 general categories of technology use, distinguished by the extent and nature of curve-fitter use and the relative dominance of mathematics versus reality affecting the development and evaluation of models. Data suggested that strategy choice was influenced by task characteristics and interactions with other student modelers. A grounded hypothesis on strategy selection and use was formulated.

The role of immunity in the epidemiology of gonorrhoea, chlamydial infection and trichomoniasis: insights from a mathematical model

2011 ◽  
Vol 139 (12) ◽  
pp. 1875-1883 ◽  
Author(s):  
L. F. JOHNSON ◽  
R. E. DORRINGTON ◽  
D. BRADSHAW
Keyword(s):  
Mathematical Models ◽  
South African ◽  
Chlamydial Infection ◽  
Bayes Factors ◽  
Prevalence Data ◽  
Sexually Transmitted ◽  
Infection Models ◽  
The Standard Model ◽  
The Impact

SUMMARYMost mathematical models of sexually transmitted infections (STIs) assume that infected individuals become susceptible to re-infection immediately after recovery. This paper assesses whether extending the standard model to allow for temporary immunity after recovery improves the correspondence between observed and modelled levels of STI prevalence in South Africa, for gonorrhoea, chlamydial infection and trichomoniasis. Five different models of immunity and symptom resolution were defined, and each model fitted to South African STI prevalence data. The models were compared in terms of Bayes factors, which show that in the case of gonorrhoea and chlamydial infection, models that allow for immunity provide a significantly better fit to STI prevalence data than models that do not allow for immunity. For all three STIs, estimates of the impact of changes in STI treatment and sexual behaviour are significantly lower in models that allow for immunity. Mathematical models that do not allow for immunity could therefore overestimate the effectiveness of STI interventions.

The Three-dimensional structure of frozen-hydrated nudaurelia capensis β virus

1987 ◽  
Vol 45 ◽  
pp. 650-651
Author(s):  
N. H. Olson ◽  
T. S. Baker ◽  
Wu Bo Mu ◽  
J. E. Johnson ◽  
D. A. Hendry
Keyword(s):  
South African ◽  
Rna Virus ◽  
Carbon Film ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Electron Dose ◽  
Total Electron ◽  
Three Dimensional Structure ◽  
Negative Stain ◽  
Dimensional Reconstruction

Nudaurelia capensis β virus (NβV) is an RNA virus of the South African Pine Emperor moth, Nudaurelia cytherea capensis (Lepidoptera: Saturniidae). The NβV capsid is a T = 4 icosahedron that contains 60T = 240 subunits of the coat protein (Mr = 61,000). A three-dimensional reconstruction of the NβV capsid was previously computed from visions embedded in negative stain suspended over holes in a carbon film. We have re-examined the three-dimensional structure of NβV, using cryo-microscopy to examine the native, unstained structure of the virion and to provide a initial phasing model for high-resolution x-ray crystallographic studiesNβV was purified and prepared for cryo-microscopy as described. Micrographs were recorded ∼1 - 2 μm underfocus at a magnification of 49,000X with a total electron dose of about 1800 e-/nm2.

Suicidal Behavior in Black South Africans

Crisis ◽  
2003 ◽  
Vol 24 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Lourens Schlebusch ◽  
Naseema B.M. Vawda ◽  
Brenda A. Bosch
Keyword(s):  
South African ◽  
Suicidal Behavior ◽  
Health Care Facilities ◽  
South African Society ◽  
South Africans ◽  
The Past ◽  
The People ◽  
Care Facilities ◽  
Black South Africans ◽  
To Come

Summary: In the past suicidal behavior among Black South Africans has been largely underresearched. Earlier studies among the other main ethnic groups in the country showed suicidal behavior in those groups to be a serious problem. This article briefly reviews some of the more recent research on suicidal behavior in Black South Africans. The results indicate an apparent increase in suicidal behavior in this group. Several explanations are offered for the change in suicidal behavior in the reported clinical populations. This includes past difficulties for all South Africans to access health care facilities in the Apartheid (legal racial separation) era, and present difficulties of post-Apartheid transformation the South African society is undergoing, as the people struggle to come to terms with the deleterious effects of the former South African racial policies, related socio-cultural, socio-economic, and other pressures.

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