Effect of a novel pedal design on maximal power output and mechanical efficiency in well-trained cyclists

In this study, we evaluated the effects of a novel pedal design, characterized by a downward and forward shift of the cleat fixing platform relative to the pedal axle, on maximal power output and mechanical efficiency in 22 well-trained cyclists. Maximal power output was measured during a series of short (5-s) intermittent sprints on an isokinetic cycle ergometer at cadences from 40 to 120 rev min(-1). Mechanical efficiency was evaluated during a submaximal incremental exercise test on a bicycle ergometer using continuous VO(2) and VCO(2) measurement. Similar tests with conventional pedals and the novel pedals, which were mounted on the individual racing bike of the participant, were randomized. Maximal power was greater with novel pedals than with conventional pedals (between 6.0%, s(x) = 1.5 at 40 rev min(-1) and 1.8%, s(x) = 0.7 at 120 rev min(-1); P = 0.01). Torque production between crank angles of 60 degrees and 150 degrees was higher with novel pedals than with conventional pedals (P = 0.004). The novel pedal design did not affect whole-body VO(2) or VCO(2). Mechanical efficiency was greater with novel pedals than with conventional pedals (27.2%, s(x) = 0.9 and 25.1%, s(x) = 0.9% respectively; P = 0.047; effect size = 0.9). In conclusion, the novel pedals can increase maximal power output and mechanical efficiency in well-trained cyclists.     

Physical fitness and academic achievement in third- and fifth-grade students

The relationship between physical fitness and academic achievement has received much attention owing to the increasing prevalence of children who are overweight and unfit, as well as the inescapable pressure on schools to produce students who meet academic standards. This study examined 259 public school students in third and fifth grades and found that field tests of physical fitness were positively related to academic achievement. Specifically, aerobic capacity was positively associated with achievement, whereas BMI was inversely related. Associations were demonstrated in total academic achievement, mathematics achievement, and reading achievement, thus suggesting that aspects of physical fitness may be globally related to academic performance in preadolescents. The findings are discussed with regards to maximizing school performance and the implications for educational policies.     

The power of a family archive

Traditionally, an archive of family letters provides primary source materials for historians. The family archive described in this article does provide detailed insight into the suffering of several Jews in Germany and France before and during World War II. It serves as a memorial to several individuals who were murdered by the Nazis. It is also a moving testimony of the cost of war. As such, it can be seen as contributing to the wider historical record of the Holocaust. But in addition, this family archive also opened an entire series of new relationships with previously unknown blood relatives scattered across the globe, with an artist drawing the archive into a creative remembrance project, and also with individuals interested in the history of their community in Germany, which was my father??s birthplace. This family archive demonstrates values of archives parallel to their historical significance. It provides a meaningful illustration for how they can, in an unanticipated and unpredictable fashion, serve as a device for forging contemporary and ongoing familial, interpersonal, and social relationships. Ultimately, this archive of family letters, created in the midst of pain and anguish and death, has laid a new foundation of commemoration and remembrance.     

Differential trust between parents and teachers of children from low-income and immigrant backgrounds

This study was designed to investigate the trust relationship between parents and teachers in first grade. Additional research questions were whether trust was related to ethnicity and reading performance. The five facets of trust; benevolence, reliability, competence, honesty and openness, were measured on a 4-point Likert scale. Reading performance was measured by the three-minute test. Parents were found to have more trust in the reliability, competence and honesty of teachers than teachers in parents. Native-Dutch and immigrant parents have the same trust level towards their children’s teacher. However, teachers reported lower trust levels on all five facets of trust for immigrant parents. Our findings indicated that ethnicity has no influence on parents trust in teachers, but ethnicity may explain teachers’ trust in parents. Some support was found for the assumption that teachers’ trust plays a role in reading performance. Children were found to have higher reading performance when teachers reported higher trust in the benevolence and openness of parents.     

未来气候变化对鄱阳湖区土地利用变化的影响评估

为了评估未来气候变化可能对鄱阳湖区土地利用变化产生的影响,本文根据IPCC的建议,利用新近建立的基于主体的土地利用变化模拟模型,详细分析了4种气候变化情景下鄱阳湖区1985-2035年的土地利用变化过程。这4种气候变化情景分别为A1B(经济高速增长模式)、A2(区域经济多样化增长模式)、B1(引进更多清洁能源的经济增长模式)和情景4(无气候变化模式)。在这些气候变化情景中,由于耕地的农业生产潜力差异显著,农户主体的收入和他们对土地利用方式的决策也发生了相应的改变。通过对这一过程的模拟和结果分析,发现气候变化可能有利于鄱阳湖区土地利用变化向着环境友好的方向自我调整。与A1B和A2两种气候变化情景相比,B1情景对土地利用变化的影响更具环境友好性。     

Maze patrolling by rats with and without food reward

The effects of food reward on rats’ behavior in radial and Dashiell tunnel mazes were examined in two experiments. In the first, with animals at ad-lib body weights, food reward reduced speed of movement at the food locations, but did not affect the patterns of movement in either maze. Exploratory efficiency in the Dashiell maze was unaffected by food reward, and spontaneous patrolling of the radial maze by the nonrewarded animals was comparable to the behavior, reported by others, of rats running for food reward on elevated eight-arm mazes. In the second experiment, with subjects maintained at 80% of ad-lib body weights, there was some evidence for “winstay” learning: food-rewarded rats in the Dashiell maze were relatively more active near the food locations than were the nonrewarded animals, and more rewarded than nonrewarded rats revisited all food locations in the radial maze. Nonetheless, exploratory efficiency in the Dashiell maze was unaffected by food reward, as was patrolling efficiency in the radial maze, which was again comparable to that of rats on elevated mazes. The similarity in behavior of rewarded and nonrewarded animals in these mazes implies that the major determinant of their behavior, whether or not food reward is provided, is a spontaneous tendency to avoid places recently visited.