Effects of muscle-tendon length on joint moment and power during sprint starts

The aim of this study was to examine the effects of muscle-tendon length on joint moment and power during maximal sprint starts. Nine male sprinters performed maximal sprint starts from the blocks that were adjusted either to 40 degrees or 65 degrees to the horizontal. Ground reaction forces were recorded at 833 Hz using a force platform and kinematic data were recorded at 200 Hz with a film camera. Joint moments and powers were analysed using kinematic and kinetic data. Muscle - tendon lengths of the medial gastrocnemius, soleus, vastus medialis, rectus femoris and biceps femoris were calculated from the set position to the end of the first single leg contact. The results indicated that block velocity (the horizontal velocity of centre of mass at the end of the block phase) was greater (P < 0.01) in the 40 degrees than in the 65 degrees block angle condition (3.39 +/- 0.23 vs. 3.30 +/- 0.21 m . s(-1)). Similarly, the initial lengths of the gastrocnemius and soleus of the front leg in the block at the beginning of force production until half way through the block phase were longer (P < 0.001) in the 40 degrees than in the 65 degrees block angle condition. The initial length and the length in the middle of the block phase were also longer in the 40 degrees than in the 65 degrees block angle condition both for both the gastrocnemius (P < 0.01) and soleus (P < 0.01-0.05) of the rear leg. In contrast, the initial lengths of the rectus femoris and vastus medialis of the front leg were longer (P < 0.05) in the 65 degrees than in the 40 degrees block angle condition. All differences gradually disappeared during the later block phase. The peak ankle joint moment (P < 0.01) and power (P < 0.05) during the block phase were greater in the 40 degrees than in the 65 degrees block angle condition for the rear leg. The peak ankle joint moment during the block phase was greater (P < 0.05) in the 40 degrees block angle for the front leg, whereas the peak knee joint moment of the rear leg was greater (P < 0.01) in the 65 degrees block angle condition. The results suggest that the longer initial muscle-tendon lengths of the gastrocnemius and soleus in the block phase at the beginning of force production contribute to the greater peak ankle joint moment and power and consequently the greater block velocity during the sprint start.     

Dimensions of learning process over global environmental problems： An evaluation of roger conceptual learning method regarding Turkish undergraduate students

The main objectives of the study have been testing Roger conceptual learning method with regard to Turkish students and to investigate the applicability of the method on graduate students. The experimental group was formed by l0 volunteer students. The study lasted 16 weeks according to group discussion method. In this period, global environmental problems were handled under 8 headings. The research data was gathered from students＇ diaries or through semi-structured group interviews. The data was evaluated using the content analysis method. In the results of analysis, it was achieved that first three dimensions of Roger model were formed in most students and the last two dimensions were significant in some students. Therefore, it might be stated that Roger conceptual learning method handled in the study, not only with its conceptual but also emotional and pedagogic dimensions, functions similarly on Turkish graduate students as well.     

Science policy in the Arab world

The paper gives an overview of recent trends in the development of policies and technology in the Arab world. It describes the problems that Arab policy-makers must address in order to set the Arab world on the road to scientific and technological self-reliance, with special emphasis on the shortcomings of the Arab education system and the problem of the brain drain. It also discusses the development of Arab policies on science and technology in the context of the need to democratize Arab society as a prerequisite to real advancement. And finally it surveys the efforts that Arab policy-makers have made in recent years to formulate coherent inter-Arab policies on science and technology. Arab national policy on science and technology for development must be formulated in accordance with the concepts of international co-operation and take full advantage of the vehicles for co-operation that exist today.

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Zusammenfassung Der Bericht gibt einen Überblick über jüngste Tendenzen in politischen und technologischen Richtungen der arabischen Länder. Er geht ein auf die Probleme, denen sich arabische Politiker zuwenden müssen, um die arabische Welt auf den Pfad zur wissenschaftlichen und technischen Selbstverantwortung zu führen. Dabei werden besonders die Unzulänglichkeiten im arabischen Erziehungs-system und das Problem desBrain Drain berücksichtigt. Im Rahmen der als notwendig erachteten Demokratisierung der arabischen Gesellschaft wird die Entwicklung der arabischen Wissenschaftspolitik als Voraussetzung für einen realen Fortschritt diskutiert. Anschließend wird ein Überblick gegeben über die jüngsten Bestrebungen arabischer Politiker, eine kohärente Politik der Wissenschaft und Technik zu entwickeln. Die nationale arabische Politik der Wissenschaft und Technik für Entwicklung muß gemäß den Konzepten der internationalen Zusammenarbeit formuliert und von Hilfsmitteln für die Zusammenarbeit, wie sie heute bestehen Gebrauch machen.

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Résumé Cet article donne un panorama des tendances récentes du développement des politiques et de la technologie dans le monde arabe. Il décrit les problèmes auxquels les hommes politiques arabes se heurtent pour mettre le monde arabe en route vers l'indépendance scientifique et technologique, en plaçant un accent spécial sur les insuffisances du système éducatif arabe et le problème de l'exode des cerveaux. Il examine également le développement des politiques arabes en matière de science et technologie dans le contexte de la nécessité de démocratisation de la société arabe en tant que condition sine qua non d'un réel progrès. On y étudie les efforts que les hommes politiques arabes ont faits au cours des dernières années pour formuler des politiques inter-arabes en matière de science et de technologie. On remarque dans cet article que l'établissement d'une démocratie dans la vie arabe est une nécessité si l'on veut asseoir une véritable politique arabe en matière de science et de technologie dans le monde arabe. C'est à cette fin que l'on cite dans ce document quelques principes généraux qui peuvent guider la politique arabe en matière de recherche scientifique et de technologie. Le développement de la politique nationale arabe dans ce domaine doit être formulé d'après les concepts de la coopération internationale et bénéficier des véhicules de coopération qui existent déjà.

     

A practical guide for the fabrication of microfluidic devices using glass and silicon

This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow.