20 research outputs found
Language and learning science in South Africa
South Africa is a multilingual country with 11 official languages. However, English dominates as the language of access and power and although the Language-in- Education Policy (1997) recommends school language policies that will promote additive bilingualism and the use of learners' home languages as languages of learning and teaching, there has been little implementation of these recommendations by schools. This is despite the fact that the majority of learners do not have the necessary English language proficiency to successfully engage with the curriculum and that teachers frequently are obliged to resort to using the learners' home language to mediate understanding. This research investigates the classroom language practices of six Grade 8 science teachers, teaching science through the medium of English where they and their learners share a common home language, Xhosa. Teachers' lessons were videotaped, transcribed and analysed for the opportunities they offered learners for language development and conceptual challenge. The purpose of the research is to better understand the teachers' perceptions and problems and to be able to draw on examples of good practice, to inform teacher training and to develop a coherent bilingual approach for teaching science through the medium of English as an additional language
A model of the pre-assessment learning effects of summative assessment in medical education
Codeswitching amongst zulu‐speaking teachers and their pupils: Its functions and implications for teacher education
Generalized Potential Energy Finite Elements for Modeling Molecular Nanostructures
The potential energy of molecules
and nanostructures is commonly
calculated in the molecular mechanics formalism by superimposing bonded
and nonbonded atomic energy terms, i.e. bonds between two atoms, bond
angles involving three atoms, dihedral angles involving four atoms,
nonbonded terms expressing the Coulomb and Lennard-Jones interactions,
etc. In this work a new, generalized numerical simulation is presented
for studying the mechanical behavior of three-dimensional nanostructures
at the atomic scale. The energy gradient and Hessian matrix of such
assemblies are usually computed numerically; a potential energy finite
element model is proposed herein where these two components are expressed
analytically. In particular, generalized finite elements are developed
that express the interactions among atoms in a manner equivalent to
that invoked in simulations performed based on the molecular dynamics
method. Thus, the global tangent stiffness matrix for any nanostructure
is formed as an assembly of the generalized finite elements and is
directly equivalent to the Hessian matrix of the potential energy.
The advantages of the proposed model are identified in terms of both
accuracy and computational efficiency. In the case of popular force
fields (e.g., CHARMM), the computation of the Hessian matrix by implementing
the proposed method is of the same order as that of the gradient.
This analysis can be used to minimize the potential energy of molecular
systems under nodal loads in order to derive constitutive laws for
molecular systems where the entropy and solvent effects are neglected
and can be approximated as solids, such as double stranded DNA nanostructures.
In this context, the sequence dependent stretch modulus for some typical
base pairs step is calculated