Energy balance of locomotion with pedal-driven watercraft

In this study, we examined the mechanics and energetics of locomotion with a paddle-wheel boat and a water bike. Power output (Wtot) was measured directly on the water bike by means of an instrumented chain-ring. The simultaneous assessment of oxygen uptake (VO2) allowed the computation of the "overall" efficiency of locomotion (etao = Wtot/VO2). Mean etao was 0.27 (s = 0.02), which was unaffected by the speed, and was assumed to be the same for the two boats as both are semi-recumbent bicycles. For the paddle-wheel boat, Wtot was then obtained from etao and measures of VO2. The power to overcome (passive) drag was calculated as Wd = D x v (where D is the force measured by means of a load cell when towing the boats at given speeds). Propelling efficiency was calculated as etap = Wd/Wtot, which was lower with the paddle-wheel boat (mean 0.35, s = 0.01) than with the water bike (mean 0.57, s = 0.01). The observed differences in etap and Wd explain why at the highest speed tested (approximately 3 m s(-1), the energy required to cover a unit distance with the water bike is similar to that required to move the paddle-wheel boat at 1.3 m s-1).     

The energetics and benefit of an arm swing in submaximal and maximal vertical jump performance

The aims of this study were to investigate the energy build-up and dissipation mechanisms associated with using an arm swing in submaximal and maximal vertical jumping and to establish the energy benefit of this arm swing. Twenty adult males were asked to perform a series of submaximal and maximal vertical jumps while using an arm swing. Force, motion and electromyographic data were recorded during each performance and used to compute a range of kinematic and kinetic variables, including ankle, knee, hip, shoulder and elbow joint powers and work done. It was found that the energy benefit of using an arm swing appears to be closely related to the maximum kinetic energy of the arms during their downswing, and increases as jump height increases. As jump height increases, energy in the arms is built up by a greater range of motion at the shoulder and greater effort of the shoulder and elbow muscles but, as jump height approaches maximum, these sources are supplemented by energy supplied by the trunk due to its earlier extension in the movement. The kinetic energy developed by the arms is used to increase their potential energy at take-off but also to store and return energy from the lower limbs and to "pull" on the rest of the body. These latter two mechanisms become more important as jump height increases with the pull being the more important of the two. We conclude that an arm swing contributes to jump performance in submaximal as well as maximal jumping but the energy generation and dissipation sources change as performance approaches maximum.     

The educational approach within Colombia's nutrition plan (PAN)

With the knowledge that malnutrition affects the quality of life of an individual, the Colombian Government set up in 1976 a unique multi-sectorial plan (PAN), to combat the country's serious malnutrition. Government agencies and private industries in the sectors of production, distribution, health, sanitation, and education have coordinated their previously independent efforts. Among the interesting aspects are the coordination of sectors through work at various levels and through control of the budget, the limitation of bureaucracy, and the decentralization of decision-making. The ongoing attempts to overcome the difficulties encountered include making decisions in the face of inconclusive knowledge on what constitutes a well-balanced diet; combating the lack of knowledge of professionals about the environment of the poorest percentage of the population; and revising the traditional teaching method to make it more successful through a multi-media approach to assure wider coverage and more impact for the least cost, using materials such as games, puppets, posters and radio.

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Zusammenfassung In der Erkenntnis, dass Untererernährung die Lebensqualität des Menschen beeinträchtigt, erstellte die kolumbianische Regierung im Jahre 1976 einen einzigartigen, mehrere Sektoren umfassenden Plan (Pan), um die schwerwiegende Unterernährung im Lande zu bekämpfen. Gemäss diesem Plan werden jetzt die früher zerstreuten Bemühungen von Behörden und privaten Industrieunternehmen auf den Sektoren Produktion, Verteilung, Gesundheit, Kanalisation und Erziehung koordiniert. Zu den interessantesten Aspekten gehören die Koordinierung von Sektoren durch Arbeit auf verschiedenen Ebenen sowie durch Kontrolle der Etats, die Beschränkung der Bürokratie und die Dezentralisierung von Entscheidungsbefugnissen. Unter den Versuchen, die bestehenden Schwierigkeiten zu überwinden, werden hervorgehoben: Entscheidungen angesichts unzureichenden Verständnisses von ausgewogener Ernährung; Bekämpfung des Mangels an Kenntnissen von Umweltspezialisten über den ärmsten Teil der Bevölkerung; und Revision der traditionellen Lehrmethoden mit dem Ziel, sie durch Einführung eines Multi-Medienansatzes, d.h. durch den Gebrauch von Spielen, Marionetten, Plakaten und Radio erfolgreicher zu gestalten.

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Résumé Conscient du fait que la sous-alimentation affecte la qualité de vie d'un individu, le Gouvernement colombien a appliqué en 1976 un plan unique à secteurs multiples (PAN) dont le but est de combattre la sérieuse sousalimentation du pays. Les agences gouvernementales et les industries privées appartenant aux secteurs de la production, de la distribution, de la santé, de l'hygiène et de l'éducation coordonnent désormais leurs efforts précédemment dispersés. Parmi les aspects intéressants de ce plan, on relève la coordination des secteurs tant au moyen du travail à différents niveaux que du contrôle du budget, la limitation de la bureaucratie et la décentralisation de la prise de décision. Les efforts qui se poursuivent dans l'intention de venir à bout des difficultés rencontrées visent à prendre des décisions malgré les connaissances nonconcluantes de ce qui constitue un régime bien équilibré; à combattre le manque de connaissance des professionnels sur l'environnement du pourcentage le plus pauvre de la population; à réviser la méthode d'enseignement traditionnel en utilisant des moyens d'approche par multimedia, ceci afin d'assurer une plus grande couverture de la population, avec un impact supérieur, et ce au moindre prix, en utilisant comme matériel des jeux, des marionnettes, des affiches illustrées ainsi que la radio.