International Comparative Studies in Mathematics: Lessons for Improving Students’ Learning

Mathematics Education; International and Comparative Education; Learning and Instructio

Understanding the role played by parents, culture and the school curriculum in socializing young women on sexual health issues in rural South African communities

BACKGROUND: the decline in South Africa’s HIV infection rates especially among young women is encouraging. However, studies show that the 15–24-year-old cohort remains vulnerable. As they still report early sexual debut, being involved in sexual partnerships with older men as well as having unprotected sex. These risky sexual behaviors may be linked to factors such as the parent–child sexual health communication and the timing of the first talk. The quality of sexual health information received in school may also be important for enhancing healthier sexual behaviors. AIMS AND OBJECTIVES: to investigate the what, when and how sexual health communication occurs in rural South African families and to determine whether such communication patterns have changed over time. We also wanted to get an in-depth understanding of the roles played by culture, sexual health education and peers in the socialization of young women on sexual matters. METHODS: a purposive sample of (n = 55) women who were 18–35 years old was selected and interviewed in focus group discussions (FGDs). Results: the FGD findings show that parent–child communication on sexual matters in rural communities is limited to messages that warn against pregnancy. It is also laden with cultural idioms that are not well explained. The school sexual health curriculum also fails to adequately equip adolescents to make informed decisions regarding sexual matters. All this seems to leave room for reception of misguided information from peers. CONCLUSIONS: findings highlight a need for designing interventions that can create awareness for parents on the current developmental needs and sexual behavior of adolescents. For adolescents programs would need to focus on providing skills on personal responsibility, and how to change behavior to enhance sexual health.DHETDHE

Quenching of Weak Interactions in Nucleon Matter

We have calculated the one-body Fermi and Gamow-Teller charge-current, and vector and axial-vector neutral-current nuclear matrix elements in nucleon matter at densities of 0.08, 0.16 and 0.24 fm$^{-3}$ and proton fractions ranging from 0.2 to 0.5. The correlated states for nucleon matter are obtained by operating on Fermi-gas states by a symmetrized product of pair correlation operators determined from variational calculations with the Argonne v18 and Urbana IX two- and three-nucleon interactions. The squares of the charge current matrix elements are found to be quenched by 20 to 25 % by the short-range correlations in nucleon matter. Most of the quenching is due to spin-isospin correlations induced by the pion exchange interactions which change the isospins and spins of the nucleons. A large part of it can be related to the probability for a spin up proton quasi-particle to be a bare spin up/down proton/neutron. We also calculate the matrix elements of the nuclear Hamiltonian in the same correlated basis. These provide relatively mild effective interactions which give the variational energies in the Hartree-Fock approximation. The calculated two-nucleon effective interaction describes the spin-isospin susceptibilities of nuclear and neutron matter fairly accurately. However $\geq$ 3-body terms are necessary to reproduce the compressibility. All presented results use the simple 2-body cluster approximation to calculate the correlated basis matrix elements.Comment: submitted to PR

Global patterns of crop yield stability under additional nutrient and water inputs

[No abstract available

Glycoprotein isolated from eurycoma longifolia (Tongkat Ali) is capable of boosting testosterone levels in leydig cells

Eurycoma longifolia (Tongkat Ali) is renowned for its aphrodisiac potential, and its active constituent has been presumed to be a protein and more likely a glycosylated protein. In this study, the ability of the glycoprotein to increase testosterone hormone levels was investigated. The dried root powder of the plant was extracted using water under reflux. The protein fraction was separated using size-exclusion chromatography and subjected to SDS-PAGE analysis. Thereafter the protein fraction was isolated from its glycoprotein using a lectin column. Finally, TM-3 Leydig cells were treated with the isolated glycoprotein fraction (50 µg/mL). The extraction yielded 14.3% w/w protein and the SDS PAGE analysis showed a single band at approximately 20 kDa. Treatment of TM-3 Leydig cells with the glycoprotein fraction for 72 hours demonstrated an increase in testosterone levels by almost 100% (0.36 ± 0.03 nmol/L) in comparison to the untreated cells (0.18 ± 0.05 nmol/L). The findings suggested that the glycoprotein in E. longifolia root can be easily isolated because its sugar moiety can bind to a lectin affinity column. Moreover, this glycoprotein was shown to have testosterone-boosting activity. These findings identified the glycoprotein as the bioactive constituent associated with its aphrodisiac properties

Uncertainties in global crop model frameworks: effects of cultivar distribution, crop management and soil handling on crop yield estimates

Global gridded crop models (GGCMs) combine field-scale agronomic models or sets of plant growth algorithms with gridded spatial input data to estimate spatially explicit crop yields 40 and agricultural externalities at the global scale. Differences in GGCM outputs arise from the use of different bio-physical models, setups, and input data. While algorithms have been in the focus of recent GGCM comparisons, this study investigates differences in maize and wheat yield estimates from five GGCMs based on the public domain field-scale model Environmental Policy Integrated Climate (EPIC) that participate in the AgMIP Global Gridded Crop Model 45 Intercomparison (GGCMI) project. Albeit using the same crop model, the GGCMs differ in model version, input data, management assumptions, parameterization, geographic distribution of cultivars, and selection of subroutines e.g. for the estimation of potential evapotranspiration or soil erosion. The analyses reveal long-term trends and inter-annual yield variability in the EPIC-based GGCMs to be highly sensitive to soil parameterization and crop management. Absolute yield levels as well depend not only on nutrient supply but 50 also on the parameterization and distribution of crop cultivars. All GGCMs show an intermediate performance in reproducing reported absolute yield levels or inter-annual dynamics. Our findings suggest that studies focusing on the evaluation of differences in bio-physical routines may require further harmonization of input data and management assumptions in order to eliminate background noise resulting from differences in model setups. For agricultural impact assessments, employing a GGCM ensemble with its widely varying assumptions 55 in setups appears the best solution for bracketing such uncertainties as long as comprehensive global datasets taking into account regional differences in crop management, cultivar distributions and coefficients for parameterizing agro-environmental processes are lacking. Finally, we recommend improvements in the documentation of setups and input data of GGCMs in order to allow for sound interpretability, comparability and reproducibility of published results

Primordialists and Constructionists: a typology of theories of religion

This article adopts categories from nationalism theory to classify theories of religion. Primordialist explanations are grounded in evolutionary psychology and emphasize the innate human demand for religion. Primordialists predict that religion does not decline in the modern era but will endure in perpetuity. Constructionist theories argue that religious demand is a human construct. Modernity initially energizes religion, but subsequently undermines it. Unpacking these ideal types is necessary in order to describe actual theorists of religion. Three distinctions within primordialism and constructionism are relevant. Namely those distinguishing: a) materialist from symbolist forms of constructionism; b) theories of origins from those pertaining to the reproduction of religion; and c) within reproduction, between theories of religious persistence and secularization. This typology helps to make sense of theories of religion by classifying them on the basis of their causal mechanisms, chronology and effects. In so doing, it opens up new sightlines for theory and research