Evaluación de parámetros biomecánicos del lanzamiento de jabalina en lanzadores de diferente nivel de rendimiento

Mediante análisis cinemático y utilizando como muestra a lanzadores agrupados en función de la marca conseguida (grupo internacional: atletas con marca superior a los 80 metros; y grupo nacional: atletas con marca inferior a 80 metros) el objetivo del estudio se centró en determinar si alguno de los parámetros utilizados para evaluar la eficacia del gesto establece diferencias entre uno y otro grupo de lanzadores. Los resultados muestran que algunos de dichos parámetros cinemáticos ayudan a establecer los márgenes para la pertenencia a los. Del total de las 41 variables contrastadas, sólo 8 de ellas establecían diferencias significativas entre grupos para un nivel de confianza del 95%: velocidad de lanzamiento; velocidad máxima alcanzada por el codo; velocidad del codo en el instante del despegue; la altura de lanzamiento; la inclinación lateral de la línea de los hombros al inicio de la fase final; el ángulo de rotación de las caderas y de los hombros en el plano horizontal en el inicio de la fase final; y el ángulo de posición de la jabalina en el instante del despegue. El estudio se realizó a partir de los resultados obtenidos en el desarrollo del proyecto financiado por la Comisión Interministerial de Ciencia y Tecnología - CICYT (SAF95-0721-C04-04), y el proyecto financiado por el Ministerio de Educación, Cultura y Deporte junto al Centro de Investigación en Ciencias del Deporte, de referencia 08/UNI22/97, y la colaboración de la Unidad de Biomecánica del CARICD de Madrid.Peer Reviewe

Microstructural evolution of a modified HP alloy: experimental and complementary computational study

In this work is presented results of the microstructural characterization of austenitic stainless steel (HP series) modified with Nb, aged at temperatures of 750, 800, 850, 900 and 950oC in air at different times. Microstructural changes were analyzed using optical microscopy, scanning electron microscopy (SEM) equipped with (EDS), x-ray diffraction and Vickers hardness. In the as-cast condition, the microstructure consists of an austenitic matrix and eutectic carbides network, Cr, Nb-rich carbides. The Cr-rich carbides are M7C3 type, whereas, those rich in Nb are NbC. During aging, there is a second precipitation in the matrix of very fine needle form of M23C6 carbides, which leads to an increase in hardness. After that, the decreasing in hardness is associated with a coalescence phenomenon of the secondary precipitates. Computational modeling shows that M23C6 is lesser stable than M7C3 carbide

An Eulerian-Lagrangian Coupled Model for Droplets Dispersion from Nozzle Spray

In this chapter, an Euler-Lagrangian double-way coupled model is presented for simulating the liquid particle dispersion ejected from a high-pressure nozzle. The Eulerian code is advanced regional prediction system (ARPS), developed by Center of Analysis and Prediction of Storm (CAPS) and Oklahoma University, USA, which is specialized in weather simulation. This code is the double way coupled with a Lagrangian one-particle model. The theoretical remarks of the double-way coupling, the simulation of the liquid droplet trajectory, and, finally, the droplet collision in the spray cloud using a binary collision model are descripts. The results of droplet velocities and diameters are compared with experimental laboratory measurements. Finally, agrochemical spraying over a cultivated field in weak wind and high air temperature conditions is showed

INFLUENCE OF FOOTWEAR ON THE ANKL SPRAIN PRODUCTION MECHANISM IN BASKETBALL

INTRODUCTION: Vertical jump is a usual movement pattern in basketball, and it is related to ankle injuries, mainly during rebound actions when falling on another player's foot. The aim of the present study IS to determine the influence of the introduction of certain elements in the footwear on ankle protection when falling on an irregular surface. The study consisted in simulating a rebound action in which the player jumps and falls on an irregular surface, simulated by a 20" inclined plane. 12 footwear prototypes were studied, making a factorial design with the following elements: high or low top, upper vamp stabilizer, hollow midsole at midfoot level and lace anchors. 3 test subjects, students of Physical Education, took part. They performed 36 jumps each, in series of 3, with a recovering time of 3 s between jumps and 3 m between series. Each series was done wearing one of the 12 prototypes at random. Each jump was filmed at 150 Hz and then digitized. The angles of knee and ankle were calculated as a function of time. For the statistical analysis an analysis of variance (ANOVA) was made, considering as factors the elements introduced in the footwear and a level of significance of 0,05 was chosen. RESULTS: The results indicate the high top footwear limited the range of movement during ankle flexion-extension and they produce higher values of inversion than low top. With an upper vamp stabilizer, higher values of inversion were obtained than without it. On the other hand, with a hollow midsole, inversion values were lower. Introducing a movement control system in the rearfoot, by means of lace anchors, did not show influence on the studied movements. CONCLUSIONS: In this way, after landing on an irregular surface, the high top as well as an upper vamp stabilizer increase the degree of inversion, probably because these elements rigidify vertically the footwear and increase the adherence to the floor or to the irregular surface on which the subject IS. However, it must be considered that epidemiological studies state that high top footwear diminish the risk of acute ankle injuries in basketball players. The upper vamp stabilizer, on the contrary, only rigidifies vertically the footwear and it dos not offer any extra reinforcement of the joint, increasing the risk of suffering ankle injuries. REFERENCES: Stacoff, A.; Kalin, X.; Stiitsi, E. (1 989) Torsional movements of the foot during landing. Abstracs of the XI1 Congress of the International Society of Biomechanics. Los Angeles, 1085. Sussman, D. H.; Hamill, J.; Miller, M. (1988) Effect of shoe height and prophylactic taping on ankle joint motion during s~mulated basketball rebounding. In De Groot, G., Hollander, A.P.; Huijing, P.A.; Van lngen Schenau, G.J. (Eds.) Biomechanics XI-6

Memoria Riojana

La Universidad Nacional de La Rioja busca generar un espacio de contención social donde sea posible que distintos actores puedan expresar sus sentimientos y relatar sus vivencias en relación a los últimos gobiernos de facto. Buscamos la construcción de la Identidad, recuperar la memoria histórica de la provincia y proyectar estos hechos en la promoción de los Derechos Civiles y Políticos. La propuesta es un Blog abierto destinado a la Construcción de la Identidad y la Memoria de nuestra provincia para realizar publicaciones sobre distintos temas relacionados a la memoria y derechos humanos. A través del recurso informático, tanto ex presos políticos, madres de desaparecidos, abogados, sacerdotes, docentes y público en general podrán aportar experiencia y memorias.  Asimismo se buscará resaltar la figura del monseñor Enrique Angelelli víctima del genocidio, generando un listado de centros de detención clandestinos en nuestra provincia. Con este blog, no pretendemos plantear la práctica militante desde su aspecto más negativo, más allá de este y de los silencios aún persistentes, pretendemos narraciones en términos de políticas actuales, de la identificación con los jóvenes, que actualmente eligen la militancia política como una iniciativa legítima para la transformación. Creemos que estos silencios pueden comenzar a circular por nuevos senderos. Especialmente respecto de cómo la persona que transita el presente se acerca al pasado y a su propia experiencia adoptando un punto de vista crítico o una mirada idealista. A nivel nacional, el Ministerio de Educación, cuenta con un Programa de Memoria y Derechos Humanos, que se aplica a docentes de nivel secundario. En esta instancia se busca lograr la participación de alumnos secundarios,  universitarios juntamente con instituciones civiles y constituirse en una fuente de información al respecto. La comunidad participará de este proyecto mediante una convocatoria específica que se realizará con la ONG (Mi Tierra) participante y el Ministerio de Educación a través de la Dirección General de Nivel Secundario, a fin de promocionar el Blog que se constituirá en fuente de promoción de artículos sobre Memoria y Derechos Humanos

INFLUENCE OF ANKLE STABILIZERS ON SHOCK ABSORTION AND PERFORMANCE IN RUNNING AND JUMPING.

Stabilizing the ankle has been investigated as a method of prevention of ankle sprains.. Several studies have found a significant decrease in ankle injuries with an increased support. In some sports with high risk of ankle injuries like basketball, high top shoes are extensively used to reduce injuries. Nevertheless, in other Sports with also high risk, high top shoes are not so extensively used because they are considered to reduce performance in runniest with rapid lateral movements. Ankle movement is also an important shock absorptions mechanism and limiting this 'movement can lead to higher impacts suffered by the body. For these reasons, performance and shock absorptions on the one hand and, prevention of ankle sprains on the other, seem to be opposite points for the ankle support issue. The aim of this paper is to understand better the effects of ankle support in both shock attenuation and performance of jumps. The influence in performance through a obstacle course has been also investigated. Three subjects participated in the study and two types of shoes were used for the tests. The shoes had exact midsole and sole and the differences between them were only in the upper vamp. First shoe was a high top shoe with firm heel counters designed to obtain a good ankle support. The second one was a low top shoe with no heel counter. Three types of experiments were carried out. The first experiment consisted of series of three maximal jumps in which the shoes were randomized. For this test the jump height was measured. The second test was also a performance test but consisted of a obstacle court and the times were measured by a chronometer. For this test also series of three runs with randomized order of shoes were performed. For the third test two accelerometers were firmly attached to the subject's tibia and forehead. Series of three jumps at 95% of the maximal jump and reach were performed barefoot and randomly wearing the shoes. The subjects landed on their right foot over a force plate. The accelerometers and force plate were sampled at 1000 Hz. Statistical significant differences between shoes were found both in the performance tests and in the shock absorption ones. High top shoes were found to reduce the performance in jumps and obstacle course and to increase impacts that reach the forehead