Tsenang!: An interactive multimedia programme for learning Beginner Setswana

In this article the interactive computer-based nature of the Tsenang! programme for learning Beginner Setswana is explained. The structure and components of the programme are presented. The programme consists of four chapters which are divided into lessons. Specific functions, grammar, skills and lexical items are linked to the lessons. The programme also includes exercises for the assessment of the functions, grammar, skills and lexical items. The selection, order and systematic presentation of the lessons, functions, grammar, skills and lexical items as well as the exercises play an important role in the learning of Setswana in this programme. The learning process in Tsenang! is based on interaction and active participation i.e., the processes of learning and exploring new material, consulting related items, consolidating new knowledge and assessment. Keywords: language teaching; language learning; multimedia; computer assisted language learning; outcomes based education; Setswana Opsomming In hierdie artikel word die rekenaargebaseerde interaktiewe aard van die Tsenang! program vir die aanleer van Beginner Setswana verduidelik. Die struktuur en onderdele van die program word bespreek. Die program is saamgestel uit vier hoofstukke wat verdeel in verskillende lesse. Spesifieke funksies, grammatika, vaardighede en leksikale items is aan elke les gekoppel. Die program bevat ook oefeninge waarmee die funksies, grammatika, vaardighede en leksikon getoets kan word. Die seleksie, ordening en 'n sistematiese aanbieding van die hoofstukke, lesse, funksies, grammatika, vaardighede, leksikon en oefeninge speel 'n belangrike rol met die aanleer van Setswana in die program. Die leerproses in Tsenang! is gebaseer op interaktiwiteit en aktiewe deelname (dit is die prosesse van leer (verken nuwe studiemateriaal), die raadpleging van verwante items, die samevatting van verworwe kennis en toetsing). Sleutelwoorde: taalonderrig; taalverwerwing; multimedia; rekenaargesteunde taalverwerwing; uitkomsgebaseerde onderrig; Setswana (J Language Teaching: 2003 37(1): 1-12

Intercorrelation study of dietary and biochemical data from schoolchildren in the Pretoria area

No Abstrac

Evolution of community structure in the world trade web

In this note we study the bilateral merchandise trade flows between 186 countries over the 1948-2005 period using data from the International Monetary Fund. We use Pajek to identify network structure and behavior across thresholds and over time. In particular, we focus on the evolution of trade "islands" in the a world trade network in which countries are linked with directed edges weighted according to fraction of total dollars sent from one country to another. We find mixed evidence for globalization.Comment: To be submitted to APFA 6 Proceedings, 8 pages, 3 Figure

A cross-sectional study of peripartum blood transfusion in the Eastern Cape, South Africa

Background. Obstetric haemorrhage (OH) remains a major contributor to maternal morbidity and mortality. Blood transfusion is critical in OH management; yet, data on peripartum transfusion are lacking. A pilot study reported high rates of peripartum transfusion in a sample of South African (SA) hospitals, which was independently associated with HIV status.Objectives. To assess the incidence of peripartum transfusion in a sample of Eastern Cape, SA hospitals to evaluate generalisability of preceding study findings.Methods. Hospital chart reviews were conducted of all deliveries at three large regional hospitals from February to June 2013. Additional clinical data were collected for patients who sustained OH and/or were transfused.Results. A total of 7 234 women were enrolled in the study; 1 988 (27.5%) were HIV-positive. Of the 767 HIV-positive women with a CD4 count <350 cells/μL, 86.0% were on full antiretroviral therapy and 9.9% received drugs for prevention of mother-to-child transmission. The overall transfusion rate was 3.2%, with significant variability by hospital: Frere Hospital (1.5%), Dora Nginza Hospital (3.8%) and Cecilia Makiwane Hospital (4.6%). The number of red blood cell units per transfused patient and per delivery varied significantly by hospital. Bivariate analysis showed significant association between transfusion and HIV status. In a multivariate analysis, controlling for OH, age, mode of delivery, gestational age, parity and birthweight, this association (odds ratio 1.45; 95% confidence interval 0.78 - 2.71) was no longer significant.Conclusion. These findings confirm high rates of peripartum transfusion in SA. While this can be possibly ascribed to variability in practice and patient profile, variation in care and improvement in HIV treatment should be considered

Ecological management of cereal stemborers in African smallholder agriculture through behavioural manipulation

1. Africa faces serious challenges in feeding its rapidly growing human population owing to the poor productivity of maize and sorghum, the most important staple crops formillions of smallholder farmers in the continent,with yields being among the lowest in the world. 2. A complex of lepidopterous stemborers attack cereals in Africa. However, their effective control is difficult, largely as a result of the cryptic and nocturnal habits of moths, and protection provided by host stem for immature pest stages.Moreover, current control measures are uneconomical and impractical for resource-poor farmers. 3. An ecological approach, based on companion planting, known as ‘push–pull’, provides effective management of these pests, and involves combined use of inter- and trap cropping systems where stemborers are attracted and trapped on trap plants with added economic value (‘pull’), and are driven away from the cereal crop by antagonistic intercrops (‘push’). 4. Novel defence strategies inducible by stemborer oviposition have recently been discovered, leading to the attraction of egg and larval parasitoids, in locally adapted maize lines but not in elite hybrids. We also established that landscape complexity did not improve the ecosystem service of biological control, but rather provided a disservice by acting as a ‘source’ of stemborer pests colonising the crop. 5. Here we review and provide new data on the direct and indirect effects of the push–pull approach on stemborers and their natural enemies, including the mechanisms involved, and highlight opportunities for exploiting intrinsic plant defences and natural ecosystem services in pest management in smallholder farming systems in Africa

Trapping of Single Atoms with Single Photons in Cavity QED

Two recent experiments have reported the trapping of individual atoms inside optical resonators by the mechanical forces associated with single photons [Hood et al., Science 287, 1447 (2000) and Pinkse et al., Nature 404, 365 (2000)]. Here we analyze the trapping dynamics in these settings, focusing on two points of interest. Firstly, we investigate the extent to which light-induced forces in these experiments are distinct from their free-space counterparts. Secondly, we explore the quantitative features of the resulting atomic motion and how these dynamics are mapped onto variations of the intracavity field. Not surprisingly, qualitatively distinct atomic dynamics arise as the coupling and dissipative rates are varied. For the experiment of Hood et al., we show that atomic motion is largely conservative and is predominantly in radial orbits transverse to the cavity axis. A comparison with the free-space theory demonstrates that the fluctuations of the dipole force are suppressed by an order of magnitude. This effect is based upon the Jaynes-Cummings eigenstates of the atom-cavity system and represents qualitatively new physics for optical forces at the single-photon level. By contrast, even in a regime of strong coupling in the experiment of Pinkse et al., there are only small quantitative distinctions between the free-space theory and the quantum theory, so it is not clear that description of this experiment as a novel single-quantum trapping effect is necessary. The atomic motion is strongly diffusive, leading to an average localization time comparable to the time for an atom to transit freely through the cavity and to a reduction in the ability to infer aspects of the atomic motion from the intracavity photon number.Comment: 19 pages, 22 figure files, REVTEX, corrected spelling, LaTeX now produces postscript which includes figures, minor changes to figures. Final version to be published in Physical Review A, expanded summary of results in introduction, minor changes to figures and tex

QCD Strings as Constrained Grassmannian Sigma Model:

We present calculations for the effective action of string world sheet in R3 and R4 utilizing its correspondence with the constrained Grassmannian sigma model. Minimal surfaces describe the dynamics of open strings while harmonic surfaces describe that of closed strings. The one-loop effective action for these are calculated with instanton and anti-instanton background, reprsenting N-string interactions at the tree level. The effective action is found to be the partition function of a classical modified Coulomb gas in the confining phase, with a dynamically generated mass gap.Comment: 22 pages, Preprint: SFU HEP-116-9

Coherent dynamics of Bose-Einstein condensates in high-finesse optical cavities

We study the mutual interaction of a Bose-Einstein condensed gas with a single mode of a high-finesse optical cavity. We show how the cavity transmission reflects condensate properties and calculate the self-consistent intra-cavity light field and condensate evolution. Solving the coupled condensate-cavity equations we find that while falling through the cavity, the condensate is adiabatically transfered into the ground state of the periodic optical potential. This allows time dependent non-destructive measurements on Bose-Einstein condensates with intriguing prospects for subsequent controlled manipulation.Comment: 5 pages, 5 figures; revised version: added reference

Barrier effects on the collective excitations of split Bose-Einstein condensates

We investigate the collective excitations of a single-species Bose gas at T=0 in a harmonic trap where the confinement undergoes some splitting along one spatial direction. We mostly consider onedimensional potentials consisting of two harmonic wells separated a distance 2 z_0, since they essentially contain all the barrier effects that one may visualize in the 3D situation. We find, within a hydrodynamic approximation, that regardless the dimensionality of the system, pairs of levels in the excitation spectrum, corresponding to neighbouring even and odd excitations, merge together as one increases the barrier height up to the current value of the chemical potential. The excitation spectra computed in the hydrodynamical or Thomas-Fermi limit are compared with the results of exactly solving the time-dependent Gross-Pitaevskii equation. We analyze as well the characteristics of the spatial pattern of excitations of threedimensional boson systems according to the amount of splitting of the condensate.Comment: RevTeX, 12 pages, 13 ps figure