Relationship between laboratory-measured variables and heart rate during an ultra-endurance triathlon

The aim of the present study was to examine the relationship between the performance heart rate during an ultra-endurance triathlon and the heart rate corresponding to several demarcation points measured during laboratory-based progressive cycle ergometry and treadmill running. Less than one month before an ultra-endurance triathlon, 21 well-trained ultra-endurance triathletes (mean +/- s: age 35 +/- 6 years, height 1.77 +/- 0.05 m, mass 74.0 +/- 6.9 kg, = 4.75 +/- 0.42 l x min(-1)) performed progressive exercise tests of cycle ergometry and treadmill running for the determination of peak oxygen uptake (VO2peak), heart rate corresponding to the first and second ventilatory thresholds, as well as the heart rate deflection point. Portable telemetry units recorded heart rate at 60 s increments throughout the ultra-endurance triathlon. Heart rate during the cycle and run phases of the ultra-endurance triathlon (148 +/- 9 and 143 +/- 13 beats x min(-1) respectively) were significantly (P < 0.05) less than the second ventilatory thresholds (160 +/- 13 and 165 +/- 14 beats x min(-1) respectively) and heart rate deflection points (170 +/- 13 and 179 +/- 9 beats x min(-1) respectively). However, mean heart rate during the cycle and run phases of the ultra-endurance triathlon were significantly related to (r = 0.76 and 0.66; P < 0.01), and not significantly different from, the first ventilatory thresholds (146 +/- 12 and 148 +/- 15 beats x min(-1) respectively). Furthermore, the difference between heart rate during the cycle phase of the ultra-endurance triathlon and heart rate at the first ventilatory threshold was related to marathon run time (r = 0.61; P < 0.01) and overall ultra-endurance triathlon time (r = 0.45; P < 0.05). The results suggest that triathletes perform the cycle and run phases of the ultra-endurance triathlon at an exercise intensity near their first ventilatory threshold.     

Tongan secondary students’ conceptions of schooling in New Zealand relative to their academic achievement

This study examines the relationship between Tongan students’ attitudes and beliefs towards their school experiences and their academic achievement on the high-stakes National Certificate of Educational Achievement (NCEA) assessments in English and mathematics. Data were obtained from using previously published self-reported inventories on a sample of Tongan senior students in New Zealand secondary schools. Confirmatory factor analysis of students’ conceptions found good fit measurement models for each domain (teaching, learning, and assessment). Structural equation modelling was used to identify the effect of the various beliefs upon students’ total score in each subject and upon internal and externally assessed performance. It was noted that different beliefs became statistically significant predictors of performance, depending on the subject and type of assessment. Nonetheless, all three constructs played some role in at least one subject. A small-to-moderate proportion of variance in NCEA performance could be attributed to student beliefs, suggesting that efforts to help students adopt adaptive beliefs will have beneficial consequences for those students.     

Day care and family dynamics

Twenty-one dual-earner families whose preschool-aged children entered day care before 6 months of age and 19 dual-earner families whose preschool-aged children entered day care during the second year of life filled out questionnaires on the nature of their children's caregiving environment; their perceptions of the effects of day care on parent-child interaction and children's development; their overall job satisfaction; social support networks; and personal well-being, marital stress, and companionship. Mothers and fathers reported high levels of satisfaction with the caregiving environment and the effects of day care. Parental perceptions of the effects of day care on parent-child interaction and children's development did not differ as a function of time of entry into day care. Parental perceptions of selected parent-child variables were associated with job satisfaction, social support, and the marital measures. Parental perceptions of parent-child interaction were related to their perceptions of the effects of day care on children's social and cognitive skills. Mothers and fathers differed in these perceptions. There was some support for a conceptual link between marital variables and children's functioning in day care.     

Neglected and abused children of mentally retarded parents

Sixty-four neglected and abused children with a mentally retarded parent seen from one to seven years earlier, were followed to determine placement outcomes. At the time of follow-up, 11 of 64 children remained with their low functioning parents. Six children had been relinquished voluntarily for adoption and courts had terminated parental rights for 34, resulting in a total of 40 who had been adopted. Nine children were in foster care at the time of the study; two had been awarded to their nonretarded parent following divorce; and two had died. All families had received public financial assistance and medical care and used an average of 10 other services per family. Because of their cognitive limitations, most of these retarded parents were unable to benefit sufficiently from community services to enable them to care for their children. These findings point up the need for a mechanism whereby the retarded adult's right to parent and the child's right to nurturance and protection may both be preserved. Until this dilemma can be resolved, decisions to terminate parental rights in such cases should be made more quickly.     

The role of the self-system in self-regulated learning

Until recently, general assumptions were made about the importance of the self-system in self-regulation (e.g., importance of self-concept, self-efficacy, self-esteem), but the more specific underlying structures and processes of the self-system that are involved in this self-management process were rarely addressed. This article presents theoretical and empirical support for a preliminary causal model of the role of the self-system in self-regulated learning. The model postulates that for self-regulated learning processes to be engaged, students must view themselves as activators of these processes (i.e., they must possess positive self-views in general as well as have specific perceptions of competency and control in particular learning situations). The model also postulates a recursive and reciprocal relationship between the processes involved, such that continual self-evaluations of competency and control can force changes in perceptions of self, the learning task, goal importance, etc., that, in turn, exert continuing influences on motivation, use of self-regulatory processes, and actual task performance. Educational implications of the model are discussed along with future research directions.     

提高实验室大型仪器设备利用率的探索

为了提高实验室大型仪器设备的利用率,培养学生的科学研究兴趣,开发其创新潜力,针对过程控制实验室大型仪器设备进行实验教学研究与开发。阐述原有实验室资源利用存在的问题,对实验室资源进行教学应用开发,对实验教学平台实施方案进行分析和设计,加大实验室开放力度,并对实验室设备共享方案进行探索。     

Models for Chloride Ion Diffusion in Archaeological Iron

Summary

The rate at which chloride ions diffuse from archaeological iron into a treatment solution depends on how the chloride ions are initially distributed in the corrosion layer. This paper compares solutions of the diffusion equation for two limiting cases: (1) where the chloride ions are initially spread uniformly through the corrosion layer; and (2) where the chloride ions are initially concentrated at the interface between the iron and the corrosion layer. Although the first model has been used in the past to describe chloride ions diffusing from marine iron, the second is more appropriate in cases where corrosion has drawn chloride ions toward the iron surface. Because diffusion processes in archaeological iron are complicated, the limitations of both these models are discussed.     

A framework for assessing market entry opportunities for internet‐based TV

Abstract

The advent of the Internet alleviates the access bottleneck to TV distribution channels and softens licensing requirements. This lowers entry barriers to TV markets via the Internet in various forms. This paper takes the German TV sector as an example to analyse the attractiveness of TV markets for new entrants. A sequential framework for entering TV markets is introduced. The skills set of an Internet‐based TV provider for such an entry is examined. Technical feasibility, legal aspects, and potential sources of revenue are considered.

Potential above average profits due to the market's oligopolistic structure, as well as an increased contestability thanks to lower market entry barriers seem to render the German TV market attractive for new entrants. In early 2002, Internet‐based TV still faced severe technical and legal constraints. The analysis suggests that once these constraints have been overcome, the Internet could be an attractive additional distribution channel for some types of television content. While existing revenue sources from the TV sector are expected to be transferable to a certain degree, the value of innovative revenue sources based on online sales cannot yet be determined. This value will depend on the future acceptance of interactivity by the viewer (e. g. Owen 1999).     

Design-Based Research Within the Constraints of Practice: AlgebraByExample

Superintendents from districts in the Minority Student Achievement Network (MSAN) challenged the Strategic Education Research Partnership (SERP) to identify an approach to narrowing the minority student achievement gap in Algebra 1 without isolating minority students for intervention. SERP partnered with 8 MSAN districts and researchers from 3 universities to design and rigorously test AlgebraByExample, a set of 42 Algebra 1 assignments with interleaved worked examples that target common misconceptions and errors. In a year-long random-assignment study, students who received AlgebraByExample assignments had an average 7 percentage point boost on a posttest containing released items from state assessments, and students in the bottom half of the performance distribution where minority students are disproportionately concentrated had an average 10 percentage point boost on a researcher-designed assessment of conceptual understanding. AlgebraByExample is easily incorporated into any existing curriculum, and naturally serves as a launch point for mathematically rich discussion.