Effects of external loading on power output in a squat jump on a force platform: A comparison between strength and power athletes and sedentary individuals

The aim of this study was to determine the effects of external loading on power output during a squat jump on a force platform in athletes specializing in strength and power events (6 elite weight-lifters and 16 volleyball players) and in 20 sedentary individuals. Instantaneous power was computed from time-force curves during vertical jumps with and without an external load (0, 5 or 10 kg worn in a special vest). The jumps were performed from a squat position, without lower limb counter-movement or an arm swing. Peak instantaneous power corresponded to the highest value of instantaneous power during jumping. Average power throughout the push phase of the jump was also calculated. A two‐way analysis of variance showed significant interactions between the load and group effects for peak instantaneous power ( P < 0.01) and average power ( P < 0.001). Peak instantaneous power decreased significantly in sedentary individuals when moderate external loads were added. The peak instantaneous power at 0 kg was greater than that at 5 and 10 kg in the sedentary individuals. In contrast, peak instantaneous power was independent of load in the strength and power athletes. Mean power at 0 kg was significantly lower than at 5 kg in the athletes; at 0 kg it was significantly higher than at 10 kg in the sedentary males and at 5 and 10 kg in the sedentary females. In all groups, the force corresponding to peak instantaneous power increased and the velocity corresponding to peak instantaneous power decreased with external loading. The present results suggest that the effects of external loading on peak instantaneous power are not significant in strength and power athletes provided that the loads do not prevent peak velocity from being higher than the velocity that is optimal for maximal power output.     

The W(h)ine Club: women finding joy in academic work

The W(h)ine Club is a multidisciplinary women's research team which has been working together for the past 10 years. The idea for this Viewpoint piece grew as we participated in a Women in Research programme. The aim of the programme was to improve academic publications among women. A group of us in the programme found ourselves repeatedly referring to a time when we had worked together in a research project and the absolute joy we had experienced working together. We decided to write this reflection as the story of the W(h)ine Club, a space in which we complained, drank lots of wine, laughed and researched. All at the same time! What we realised was that women academics working together was a wonderful way to do research. Sharing our joys and sadness was often the glue that kept the team together and we learnt about research without realising it. In this Viewpoint we show that learning to research can be fun and that the bonds built in this process are powerful and validating.     

An Educational Case Study in Protocol Verification and Distributed Observation

This paper describes a case study presented to students in computer science during a course on formal techniques for protocol validation. The course teaches some basic notions on specification, simulation, verification, testing and distributed observation. The case study is the classical alternating-bit protocol. The exercise first consists of some simple modeling and simulation of the specification and verification of some basic service properties. It is then followed with the problem of observation of distributed executions of the protocol. This kind of experiment was found to be useful for students, since they gain an understanding of the importance and necessity of formal methods for protocol validation.     

Learning about print: the development of orthographic processing and its relationship to word reading in first grade children in French immersion

As children learn to read, they become sensitive to the patterns that exist in the ways in which their language(s) are represented in print. This skill is known as orthographic processing. We examined the nature of orthographic processing in English and French for children in the first grade of a French immersion program, and the relationship between orthographic processing and reading beyond controls for mother’s education, non-verbal reasoning, English vocabulary and phonological awareness. We found that children showed greater orthographic processing skill to patterns that were common to both of their languages than to those that occurred in just one of their languages. Across both lexical and sub-lexical orthographic processing measures, scores were related to word reading within each language, beyond our control variables. There was some evidence of cross-language relationships between orthographic processing and word reading, both for lexical and sub-lexical language-shared measures of orthographic processing. These findings suggest that children’s attention to features that are common both languages might be one source of transfer of orthographic processing to reading between languages.     

Study on Multimedia CAI Authoring Systems

Abstract

Starting with a look back at most of our school days, this article considers the possible demise of the textbook as new technologies are introduced, but is by no means sure that this will come about. Certain conditions are needed if new technologies are to take their place alongside textbooks in the eyes of teachers.     

La construcción individual del sistema de numeración convencional

Resumen

El sistema de numeración posicional de base 10 constituye un objeto cultural, resultado de un largo y dificultoso desarrollo histórico, que se convierte en un objeto de conocimiento a asimilar por el niño. En este artículo se estudia el proceso de reconstrucción individual de este instrumento intelectual, a través de las producciones gráficas espontáneas de 100 niños de edades comprendidas entre los 6 y 10 años, obtenidas en situación de invención de sistemas de notación de cantidades. Las producciones de los niños, cuyas estrategias recuerdan en muchos casos a las empleadas en los sistemas de numeración históricos, describen una génesis. Esta se extiende desde producciones que no contemplan la estabilidad de los grafismos ni la posibilidad de combinarlos, hasta las que recurren al principio del valor posicional, pasando por producciones de tipo aditivo y producciones que intentan, sin conseguirlo, la transposición del sistema de numeración convencional.     

Reflexiones sobre el lenguaje autista. I.—Análisis descrpitivos y diferencias con la disfasia receptiva

Resumen

En este articulo, se revisan las descripciones clínicas y los estudios sistemáticos que tratan de establecer los rasgos que definen al lenguaje de los autistas cuando se les compara con el dé los sujetos normales o con otras clases de alteraciones. En la última parte de él, se analizan especialmente las semejanzas y diferencias entre el lenguaje autista y el de los niños con disfasia receptiva del desarrollo y anlizaremos la llamada «tesis de continuidad», que concibe el autismo como una especie de disfasia receptiva grave. En un trabajo posterior, se analizarán más específicamente algunas de las alteraciones más características del lenguaje de los autistas (p.e. ecolalia, inversión pronominal, problemas de comprensión) y se discutirán sus anomalías y retrasos en relación con los distintos componentes (fonológico, morfosintáctico, léxico, etc.) en que puede analizarse el lenguaje.     

Bourdieu as education policy analyst and expert: a rich but ambiguous legacy

This article focuses on Bourdieu’s contribution to the analysis and transformation of the field of education. It shows that, when closely examined, Bourdieu’s writings on education reveal not only one but at least three competitive or complementary policy theories. There is a common principle to all of them, that is the invisibility of policy, which is embedded in the cognitive classifications and everyday activity of institutions. Nevertheless, while the first theory is strongly deterministic, the other two leave some room for political and pedagogical action. This article also shows that Bourdieu has exerted an important influence, both directly and indirectly, on collective representations and collective dynamics of educational politics and policy in France. This influence has lasted despite the extremely varied positions he took throughout his life and work on the relation between science and politics from strong reluctance to commit himself at the beginning of his career to academic radicalism at the end.     

Effects of math anxiety and perfectionism on timed versus untimed math testing in mathematically gifted sixth graders

This study was designed to examine the effects of math anxiety and perfectionism on math performance, under timed testing conditions, among mathematically gifted sixth graders. We found that participants had worse math performance during timed versus untimed testing, but this difference was statistically significant only when the timed condition preceded the untimed condition. We also found that children with higher levels of either math anxiety or perfectionism had a smaller performance discrepancy during timed versus untimed testing, relative to children with lower levels of math anxiety or perfectionism. There were no statistically significant gender differences in overall test performance, nor in levels of math anxiety or perfectionism; however, the difference between performance on timed and untimed math testing was statistically significant for girls, but not for boys. Implications for educators are discussed.