Maturity status effects on torque and muscle architecture of young soccer players

ABSTRACT

This study investigated the effects of maturity status on knee extensor torque and vastus lateralis architecture of young soccer players. Thirty-four males aged 13–18 years were divided into two groups: pubescent (PUB, n = 15) and postpubescent (POSP, n = 19). Torque by angle interaction was established for absolute [F(2.649, 84.771) = 9.066, p < 0.05] and relative to body mass [F(2.704, 86.533) = 4.050, p < 0.05] isometric torque with the POSP group showing greater values. Muscle volume torque-angle relationship was similar between groups. Absolute, relative to body mass, and relative to muscle volume concentric and eccentric torque-velocity relationship showed a non-significant interaction but a significant group effect in favour the POSP group for absolute and concentric torque relative to body mass. Torque-angle and torque-velocity relationship normalized by body mass allometric exponents showed a non-significant interactions and group effects. Muscle thickness (3.6 ± 0.6 vs. 3.8 ± 0.6 cm), fascicle length (8.3 ± 1.4 vs. 8.9 ± 1.6 cm) and pennation angle (15.0 ± 2.3 vs. 14.3 ± 3.2 degrees) was similar between PUB and POSP groups, respectively. Maturity status did not show a significant effect on muscle architecture and on isometric and dynamic torques when allometrically normalized.     

Product portfolio performance in new foreign markets: The EU trademark dual system

How do intellectual propriety rights (IPRs) help firms profit from their innovation? Innovation literature frequently turns to patents to measure innovative IPR, but more recent work shifts focus to the other side of IPR, namely, trademarks. This article therefore discusses the effects of trademark strategies when companies decide to introduce their product portfolios in a new foreign market. Entrants might opt for a common trademark across different country markets (integration) or use several country-specific trademarks (responsiveness). This empirical study exploits the quasi-natural experiment created by the tariff shock that affected Spain when it joined the European Union in the 1990s. Data from the automotive industry reveal how non-European companies that already operated in other European countries sought to enter Spain rapidly, using various trademark strategies. The product portfolio characteristics are fixed at entry, so this study can specify how and when trademark responsiveness versus integration affects firm performance. The results reveal that trademark responsiveness increases firm performance if the firms suffer high liabilities of foreignness or newness.     

Microstripes for transport and separation of magnetic particles

We present a simple technique for creating an on-chip magnetic particle conveyor based on exchange-biased permalloy microstripes. The particle transportation relies on an array of stripes with a spacing smaller than their width in conjunction with a periodic sequence of four different externally applied magnetic fields. We demonstrate the controlled transportation of a large population of particles over several millimeters of distance as well as the spatial separation of two populations of magnetic particles with different magnetophoretic mobilities. The technique can be used for the controlled selective manipulation and separation of magnetically labelled species.     

Experience, experimentation, and the accumulation of knowledge: the evolution of R&D in the semiconductor industry

This paper examines the interaction and impact on performance of two organizational mechanisms supporting generation and retention of knowledge: experience accumulation and experimentation. It provides evidence that generation of knowledge through experimentation and retention of knowledge through experience were significantly correlated with performance, whereas other measures of R&D commitment and organization, including several suggested by prior studies, were not. It argues that experience and experimentation can function as at least partial substitutes for one another, possessing more of one, firms may need less of the other, and provides evidence that they were so in the semiconductor industry. The evolution of practice at one firm—Intel Corporation—is explored at greater length, providing a qualitative perspective on the process by which a shift towards greater experimentation occurred.     

Preface

The International Federation for the Promotion of Mechanism and Machine Science (IFToMM) held the International Symposium on Robotics and Mechatronics (ISRM 2009) as the first in a series of conference events promoting robotics and mechantronics in the Asian IFToMM community. The first event was held in Hanoi University of Technology on Sept.     

Wie die Türken in unsere Köpfe kamen. Das Türkei-Bild in der deutschen Pädagogik zwischen 1820 und 1930

The article reconstructs the image of Turkey and the Turks that German education portrayed between 1820 and 1930. The analysis is based on educational periodicals and reference works from the historical eras of the German Confederation, the German Empire and the First World War, tracing the way old stereotypes persisted and new stereotypes arose. The study especially focuses on the opinions of German educationalists about schools in Turkey, Turkish women, Islam, the question of whether Turkey was part of Europe, and last not least on whether Ottoman educational policies were appropriate. Closely following the historical sources, the article shows how the opinions of German educationists changed according to the shift of Germany’s geopolitical interests, how their outlook went hand in hand with the views of the general press, and how they gradually came to a professional self-concept that contrasted ‘their’ educational system with what they believed was a ‘backward’ system in Turkey. At the same time they began to develop an interest in doing professional work in Turkey. The article can also be regarded as a contribution to the history of educational thinking in Germany in the course of the nineteenth century.     

Hernán Cortés: Virtù vs. Fortuna

En este trabajo analizo algunas de las hazañas del conquistador Hernán Cortés, en base a los conceptos de “virtu” y “fortuna.” Visto desde esta perspectiva, Cortés aparece como un hombre de indiscutible inteligencia y valentía personal cuyos logros políticos en Mesoamérica han sido sobre-estimados.     

Analysis of the intraseasonal stability of field test performances in young academy soccer players

This study aimed to observe the intraseasonal stability of anthropometric, technical and functional test results in academy soccer players of different age categories. In total, 103 participants (age range: 7.7–13.4 years) by 5 age categories of the same academy were recruited for this study. Players were submitted to a field-test battery comprising 3 anthropometric measurements (body mass, stature and body mass index), 6 soccer technical tests (to assess the ability of ball control, ball control with the head, pass accuracy, shooting accuracy, dribbling and dribbling with pass) and 3 functional tests (countermovement jump with the hands on the hip, countermovement jump with free hands and 15-m linear sprint) that was administered in 4 test sessions during the same season. Though anthropometric results showed a clear increment in each age category across the season, the fluctuation of technical test results depended on age category and test session. Moreover, a significant increase in the results of functional tests was observed in most of the age categories, in particular, for the assessment of lower power limb. In conclusion, collecting repeated intraseason measurements permits the identification of players’ fluctuations of performance across the season and allows coaches to make frequent adjustments of their programmes.     

Interferential therapy effect on mechanical pain threshold and isometric torque after delayed onset muscle soreness induction in human hamstrings

Abstract

This study was undertaken to examine the acute effect of interferential current on mechanical pain threshold and isometric peak torque after delayed onset muscle soreness induction in human hamstrings. Forty-one physically active healthy male volunteers aged 18?33 years were randomly assigned to one of two experimental groups: interferential current group (n = 21) or placebo group (n = 20). Both groups performed a bout of 100 isokinetic eccentric maximal voluntary contractions (10 sets of 10 repetitions) at an angular velocity of 1.05 rad · s^?1 (60° · s^?1) to induce muscle soreness. On the next day, volunteers received either an interferential current or a placebo application. Treatment was applied for 30 minutes (4 kHz frequency; 125 μs pulse duration; 80?150 Hz bursts). Mechanical pain threshold and isometric peak torque were measured at four different time intervals: prior to induction of muscle soreness, immediately following muscle soreness induction, on the next day after muscle soreness induction, and immediately after the interferential current and placebo application. Both groups showed a reduction in isometric torque (P < 0.001) and pain threshold (P < 0.001) after the eccentric exercise. After treatment, only the interferential current group showed a significant increase in pain threshold (P = 0.002) with no changes in isometric torque. The results indicate that interferential current was effective in increasing hamstrings mechanical pain threshold after eccentric exercise, with no effect on isometric peak torque after treatment.     

Factors influencing the pursuit of personal learning goals in MOOCs

MOOCs are promising opportunities for lifelong learning, but as promising as these learning opportunities seem, many learners do not succeed in pursuing their personal learning goals. Barriers to learning are the main reason for not finishing the intended (parts of the) MOOCs. This study addressed the question whether the factors age, gender, educational level, and online learning experience affect barriers faced while learning in MOOCs. The results show that it is challenging to combine work and family life with lifelong (online) learning activities, especially for learners in their early adulthood and mid-life. However, more experience with online learning positively affects individuals’ ability to cope with these challenges. Also, learners with a lower educational level may experience a lack of knowledge or difficulties with the course content. These findings may serve as input to inform potentially vulnerable learners about these issues and support them in successfully achieving their personal learning goals.