Metabolic effects of diets differing in glycaemic index depend on age and endogenous GIP

Aims/hypothesis High- vs low-glycaemic index (GI) diets unfavourably affect body fat mass and metabolic markers in rodents. Different effects of these diets could be age-dependent, as well as mediated, in part, by carbohydrate-induced stimulation of glucose-dependent insulinotrophic polypeptide (GIP) signalling. Methods Young-adult (16 weeks) and aged (44 weeks) male wild-type (C57BL/6J) and GIP-receptor knockout (Gipr −/− ) mice were exposed to otherwise identical high-carbohydrate diets differing only in GI (20–26 weeks of intervention, n = 8–10 per group). Diet-induced changes in body fat distribution, liver fat, locomotor activity, markers of insulin sensitivity and substrate oxidation were investigated, as well as changes in the gene expression of anorexigenic and orexigenic hypothalamic factors related to food intake. Results Body weight significantly increased in young-adult high- vs low-GI fed mice (two-way ANOVA, p < 0.001), regardless of the Gipr genotype. The high-GI diet in young-adult mice also led to significantly increased fat mass and changes in metabolic markers that indicate reduced insulin sensitivity. Even though body fat mass also slightly increased in high- vs low-GI fed aged wild-type mice (p < 0.05), there were no significant changes in body weight and estimated insulin sensitivity in these animals. However, aged Gipr −/− vs wild-type mice on high-GI diet showed significantly lower cumulative net energy intake, increased locomotor activity and improved markers of insulin sensitivity. Conclusions/interpretation The metabolic benefits of a low-GI diet appear to be more pronounced in younger animals, regardless of the Gipr genotype. Inactivation of GIP signalling in aged animals on a high-GI diet, however, could be beneficial

Overview of mathematical approaches used to model bacterial chemotaxis II: bacterial populations

We review the application of mathematical modeling to understanding the behavior of populations of chemotactic bacteria. The application of continuum mathematical models, in particular generalized Keller–Segel models, is discussed along with attempts to incorporate the microscale (individual) behavior on the macroscale, modeling the interaction between different species of bacteria, the interaction of bacteria with their environment, and methods used to obtain experimentally verified parameter values. We allude briefly to the role of modeling pattern formation in understanding collective behavior within bacterial populations. Various aspects of each model are discussed and areas for possible future research are postulated

Examining the Context of Strategy Instruction

The goal of literacy instruction is to teach reading and writing as tools to facilitate thinking and reasoning in a broad array of literacy events. An important difference in the disposition of children to participate in literacy experiences is the extent to which they engage in intentional self-regulated learning. The contexts attending six traditional models of strategy instruction are examined. An exploratory study, conducted with heterogeneous third graders, is reported, examining the implementation and outcomes of three models of strategy instruction—Direct Instruction, Reciprocal Teaching, and Collaborative Problem Solving—which manipulated teacher and student control of activity, as well as the instructional context.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69008/2/10.1177_074193259101200306.pd

Students’ Perceptions of Learning Processes as Co-Authors of Digital Tabletop Activities

We conducted a small-scale study in order to explore students’ perceptions of the learning processes when engaged as co-authors of content for collaborative higher order thinking skills learning tasks. We specifically designed the process to allow for self-critique – where authors can observe their creations being solved and therefore understand where they may improve their design. We collected data over a three-day period from a sample of twelve thirteen year olds, working in teams, authoring content for Digital Mysteries (a higher order thinking skills collaborative learning application based on the digital tabletop). The study was structured to follow Bloom’s taxonomy, a continuum of cognitive skills that develop during a learning process. We found that 1) rather than follow this continuum, skills developed in a non-linear manner due to the abstract nature of the authoring activity, and 2) the students’ demonstrated good metacognitive insights into the authoring task, technology and collaborative learning as a whole

Print awareness of adult illiterates: a comparison with young pre-readers and low-educated adult readers

In this study the print awareness of 25 unschooled adult illiterates in the Netherlands was compared with that of 24 pre-reading children and of 23 low-educated literate adults with approximately four years of primary schooling. The illiterates were interviewed about their experiences with writing and all participants completed six assessments of print awareness in the language they preferred (first or second language). The outcomes revealed that the three groups did not differ in distinguishing conventional written signs from other visual signs, that both groups of non-readers differed significantly from low educated readers but not from each other in knowledge of logos, inscriptions and knowledge of the written register, while the adult illiterates performed significantly better than the children on grapheme knowledge. Adult illiterates in literate societies seem to be well informed about the uses and functions of written language and about what writing looks like, but like young children they are not good at reading environmental print out of context and in explaining what exactly is represented in writing. The variation in reactions within the group of illiterate adults could be related to existing models of emergent literacy. Implications for adult literacy education are discussed

Boundary objects and boundary crossing for numeracy teaching

In this paper, we share analysis of an episode of a pre-service teacher’s handling of a map artefact within his practicum teaching of ‘Mathematical Literacy’ in South Africa. Mathematical Literacy, as a post-compulsory phase subject in the South African curriculum, shares many of the aims of numeracy as described in the international literature— including approaches based on the inclusion of real life contexts and a trajectory geared towards work, life and citizenship. Our attention in this paper is focused specifically on artefacts at the boundary of mathematical and contextual activities. We use analysis of the empirical handling of artefacts cast as ‘boundary objects’ to argue the need for ‘boundary crossing’ between mathematical and contextual activities as a critical feature of numeracy teaching. We pay particular attention to the differing conventions and extents of applicability of rules associated with boundary artefacts when working with mathematical or contextual perspectives. Our findings suggest the need to consider boundary objects more seriously within numeracy teacher education, with specific attention to the ways in which they are configured on both sides of the boundary in order to deal effectively with explanations and interactions in classrooms aiming to promote numeracy