Mixed-method pre-cooling reduces physiological demand without improving performance of medium-fast bowling in the heat

This study examined physiological and performance effects of pre-cooling on medium-fast bowling in the heat. Ten, medium-fast bowlers completed two randomised trials involving either cooling (mixed-methods) or control (no cooling) interventions before a 6-over bowling spell in 31.9±2.1°C and 63.5±9.3% relative humidity. Measures included bowling performance (ball speed, accuracy and run-up speeds), physical characteristics (global positioning system monitoring and counter-movement jump height), physiological (heart rate, core temperature, skin temperature and sweat loss), biochemical (serum concentrations of damage, stress and inflammation) and perceptual variables (perceived exertion and thermal sensation). Mean ball speed (114.5±7.1 vs. 114.1±7.2 km · h(-1); P = 0.63; d = 0.09), accuracy (43.1±10.6 vs. 44.2±12.5 AU; P = 0.76; d = 0.14) and total run-up speed (19.1±4.1 vs. 19.3±3.8 km · h(-1); P = 0.66; d = 0.06) did not differ between pre-cooling and control respectively; however 20-m sprint speed between overs was 5.9±7.3% greater at Over 4 after pre-cooling (P = 0.03; d = 0.75). Pre-cooling reduced skin temperature after the intervention period (P = 0.006; d = 2.28), core temperature and pre-over heart rates throughout (P = 0.01-0.04; d = 0.96-1.74) and sweat loss by 0.4±0.3 kg (P = 0.01; d = 0.34). Mean rating of perceived exertion and thermal sensation were lower during pre-cooling trials (P = 0.004-0.03; d = 0.77-3.13). Despite no observed improvement in bowling performance, pre-cooling maintained between-over sprint speeds and blunted physiological and perceptual demands to ease the thermoregulatory demands of medium-fast bowling in hot conditions.     

La enseñanza de contenidos específicos en matemáticas

¿Matemáticas para todos o matemáticas de élite? ¿Lenguaje matemático o matemática aplicada? En la base de las últimas reformas educativas de todo el mundo no dejan de estar presentes dilemas, reales unas veces, ficticios otras, que tienen mucho que ver con los supuestos políticos—ideológicos—que sustenten los diseñadores de esa reforma respecto al papel de la educación y a los que no se sustrae la enseñanza de las matemáticas…     

Children's Developing Mathematics in Collective Practices: A Framework for Analysis

This article presents a cultural-developmental framework for the analysis of children's mathematics in collective practices and illustrates the heuristic value of the framework through the analysis of videotaped episodes drawn from a middle-school classroom. The framework is presented in 2 related parts. The first targets the children's emerging mathematical goals in collective practices, with a particular focus on the complex role that artifacts play in children's emerging goals. The second part focuses on children's developing mathematics that takes form in their goal-directed activities: (a) Microgenetic analyses concern the process whereby children structure cultural forms like artifacts to serve particular functions as they accomplish emerging mathematical goals; (b) sociogenetic analyses concern the spread or travel of mathematical forms and associated functions within a community of individuals; and (c) ontogenetic analyses concern the interplay between the forms that children use and the functions that they serve over the course of children's development. The analyses of the classroom episodes points to the promise (and limitations) of the framework as a method for furthering our understanding of the interplay between social and developmental processes in children's mathematics.     

The context of their lives

Abstract

This paper explores the Ecology of Human Development Model (Bronfenbrenner, 1979) as applied to the lives of students enrolled in the Early Childhood Education program at James Madison University (Virginia). This model provided insights into who our students are, their experiences, beliefs and values and how they define themselves; secondly, the process of reflection provided an opportunity for students to examine their lives as part of a larger social context; and thirdly, by valuing the process, it is hoped that students would recognize the importance of coming to know the children they teach. It is imperative that students are well prepared for teaching an increasingly diverse population (NCATE Standard I.E.2). Our belief is that in order for prospective teachers to appreciate diversity in classrooms, they need first to examine the context of their own lives. © 2001 Elsevier Science Inc. All rights reserved.