Teacher's use of exemplification and explanations in mediating the object of learning

A research report submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science. November 2017.This study examined teachers' use of exemplification and explanations in the teaching of algebraic expressions. In particular the focus was on the selection and sequencing of examples as well as what a teacher does with these examples in terms of their explanations to maintain the focus or object of learning. Adler and Ronda's (2015) Mathematical Discourse in Instruction (MDI) framework was the foundation of this study's conceptual and analytical framework and was complemented with the work of Stein (2000) and Moschovich (1999, 2015). Data was collected from two Grade 8 teachers through the use of video-recordings and transcripts. The data was then analysed based on the themes that emerged from the conceptual framework. The findings revealed that the examples themselves had the potential to restrict the object of learning and together with the teacher's corresponding explanatory talk could reduce or shift the object of learning from translating algebraic expressions to focusing on procedures. The findings show how each component of MDI worked separately and then together to mediate the of the object of learning, but this study has additionally highlighted how the components themselves, namely exemplification and explanatory talk, have a direct effect on each other.LG201

Cathodoluminescence Image Processing of High TC Superconductors

Cathodoluminescence (CL) in the Scanning Electron Microscope (SEM) was performed for both ceramic pellets and thin films of YBaCuO high TC superconductors. Image processing provided additional quantitative information. For single phase films, we demonstrated the possibility to create thickness maps in real time from the CL pictures. The gradual thickness variation within the sample was revealed by the histogram of the thickness image. The continuity of the film was observed at a few threshold thicknesses values, defined by the fraction of the occupied area. At the conduction threshold value, the location and width of the conducting paths could be estimated. The analysis was of a lateral resolution better than 1 μm and of a submicron thickness resolution. Insulating impurity grains embedded in the YBaCuO ceramic pellet, which could not be recognized by secondary electrons, were revealed by the CL mode in the SEM. Their long luminescence lifetime was recorded at different time scales and provided an estimation of the lifetime and density of generated carriers. This analysis can be applied to any other high TC superconductors

Whole genome sequences to assess the link between antibiotic and metal resistance in three coastal marine bacteria isolated from the mummichog gastrointestinal tract

International audienceAntibiotic resistance is a global public health issue and metal exposure can co-select for antibiotic resistance. We examined genome sequences of three multi-drug and metal resistant bacteria: one Shewanella sp., and two Vibrio spp., isolated from the gut of the mummichog fish (Fundulus heteroclitus). Our primary goal was to understand the mechanisms of co-selection. Phenotypically, the strains showed elevated resistance to arsenate, mercury, and various types of β-lactams. The genomes contained genes of public health concern including one carbapenemase (bla OXA-48). Our analyses indicate that the co-selection phenotype is mediated by chromo-somal resistance genes and cross-resistance. No evidence of co-resistance was found; most resistance genes were chromosomally located. Moreover, the identification of many efflux pump gene homologs indicates that cross-resistance and/or co-regulation may further contribute to resistance. We suggest that the mummichog gut microbiota may be a source of clinically relevant antibiotic resistance genes

Genome-facilitated discovery of RND efflux pump-mediated resistance to cephalosporins in Vibrio spp. isolated from the mummichog fish gut

International audienc

NOVAS POSSIBILIDADES EM UM MUNDO CALEIDOSCÓPICO: LEITURAS ALTERNATIVAS PARA NARRATIVAS EM CONFLITO

O presente estudo visa, ao se debruçar sobre alguns elementos das narrativas históricas oficiais judaica-israelense e árabe-palestina, buscar leituras alternativas que visem a cooperação entre seus diferentes atores, ao invés da exclusão e do conflito

Microbial pathways for the mobilization of mercury as Hg(O) in anoxic subsurface environments

The goal of our project which was initiated in June 2005 is focused on the presence of merA in microbial communities of anoxic environments and the effect of anaerobic respiratory pathways on MR expression and activities. The following progress has been made to date: PCR primers were designed to span the known phylogenetic range of merA genes of Gram-negative bacteria. In control experiments, these primers successfully amplified a 288 bp region at the 3? end of previously characterized merA genes from Shewanella putrefaciens pMERPH, Acidithiobacillus ferrooxidans, Pseudomonas stutzeri pPB, Tn5041, Pseudomonas sp. K-62, and Serratia marcescens pDU1358

Regulation and voluntarism: A case study of governance in the making

Abstract In this article I analyze a multi-stakeholder process of environmental regulation. By grounding the article in the literature on regulatory capitalism and governance, I follow the career of a specific legislative process: the enactment of Israel's Deposit Law on Beverage Containers, which aims to delegate the responsibility for recycling to industry. I show that one crucial result of this process was the creation of a non-profit entity licensed to act as a compliance mechanism. This new entity enabled industry to distance itself from the responsibility of recycling, and thereby frustrated the original objective of the legislation, which was to implement the principle of "extended producer responsibility." Furthermore, this entity, owned by commercial companies and yet acting as an environmentally friendly organization, allowed industry to promote an anti-regulatory agenda via a "civic voice." The study moves methodologically from considering governance as an institutional structure to analyzing the process of "governancing," through which authoritative capacities and legal responsibilities are distributed among state and non-state actors. Two key findings are that this process and its outcome (i) are premised on an ideology of civic voluntarism, which ultimately delegates environmental responsibilities to citizens; and (ii) facilitate an anti-regulatory climate that serves commercial interests.r ego_1063 360..37

A pequena Iugoslávia no Brasil: a etnografia de uma família

Por meio de relatos de membros da família e de amigos próximos, além das minhas recordações de infância, pretendo, neste artigo, organizar alguns aspectos da memória de uma pequena comunidade judaica, de origem iugoslava, que se estabeleceu na cidade de São Paulo após a Segunda Guerra Mundial. The little Yugoslavia in Brazil: the ethnography of a family - Abstract: Through the reports of family members and close friends beside my childhood memories, I intend in this article to organize some aspects of the memory of a small jewish community from Yugoslavian origin who settled in São Paulo after the Wold War II