CORRELATION OF SOME KINEMATIC PARAMETERS WITH COMPETITIVE SUCCESS OF SKIJUMPERS AT THE 1994 WORLD CHAMPIONSHIP IN SKI-FLIGHTS IN PLANICA

The purpose of this research was to evaluate selected biomechanical parameters and find the level of correlation to competitive success at the 1994Planica ski-flights competition. The subject sample comprised of 28 ski-jumpers. They were divided into three qualitative groups; B - best, M - medium, L - low, according to their success measured by the length of the jump. The flight phase was measured for both official jumps at two points. The first was 8 m beyond the edge of the take-off table and the second 78 m beyond. The data on the kinematic parameters were obtained with the 3D video analysis system CONSPORT. One-way analysis of variance was used to test the differences between the groups and correlation analysis to test the tie with the jump length. The results of the analysis of variance showed statistically significant differences (p < 0.05) between the "quality-groups" in the flight elevation angle in the middle part of the flight. Better jumpers flew at a smaller angle and were more inclined forward during flight. They had a smaller angle between the "body-bow-line" (line joining the shoulder and ankle joint) and the skies in the XY plane. Similar tendencies were also found for the other two angles, which are supposed to be indicators of aerodynamic efficiency from the viewpoint of the horizontal component of air drag. A significant correlation(p< 0.05) was therefore found of the angle between the trunk and the skies with the angle between the "body-bow-line" and the horizontal. A significant factor for length of the jump was also the angle between the skies in the XZ plane. Better jumpers had a slightly greater angle between the skies (M=25.3 degrees)in the middle part of the flight and were also more extended in the hips (M = 175degrees).The results therefore mainly affirm the theoretically defined tendencies of the ski-flights technique and fully conform to findings of flight analysis performed at the World Cup competition in Planica (K= 120 m) in the season 1992/93

Effects of Several Bioinspired Methods on the Stability of Coevolutionary Complexification

We study conditions for sustained growth of complexity in an abstract model of parasitic coevolution. Previous research has found that complexification is hard to achieve if the evolution of the symbiont population is constrained by the hosts but the evolution of the hosts is unconstrained, or, more generally, if the task difficulty is much higher for the symbionts than for the hosts. Here we study whether three bio inspired methods known from previous research on achieving stability in coevolution (balancing, niching, and reduced resistance) can restore complexification in such situations. We find that reduced resistance, and to a lesser degree niching, are successful if applied together with truncation selection, but not if applied together with fitness proportional selection

Biologische und biomechanische Grundlagen der arthroskopischen Rotatorenmanschettenrekonstruktion

Zusammenfassung: Eine erfolgreiche arthroskopische Rotatorenmanschettenrekonstruktion im Langzeitverlauf ist nicht nur von der rein technischen Wiederherstellung der Kontinuität des Muskel-Sehnen-Knochen-Komplexes, sondern auch von vielen weiteren Faktoren abhängig. Neben einer korrekten und schonenden Operationstechnik spielen u.a. biologische Faktoren wie die Muskel- und Sehnenqualität der Rotatorenmanschette sowie die Knochenqualität der Reinsertionszone für das Outcome eine wesentliche Rolle. In diesem Zusammenhang sind insbesondere die fettige Infiltration, Atrophie und Retraktion der rupturierten Rotatorenmanschette, die Sehnendegeneration sowie Osteopenie der Reinsertionszone an den Tuberkula zu berücksichtigen. Des Weiteren müssen grundlegende biomechanische Prinzipien bei der Nahttechnik und Fadenankerplatzierung beachtet werden, um ein technisch bedingtes Versagen der Refixation zu vermeide

Evolving neural networks to follow trajectories of arbitrary complexity

Many experiments have been performed that use evolutionary algorithms for learning the topology and connection weights of a neural network that controls a robot or virtual agent. These experiments are not only performed to better understand basic biological principles, but also with the hope that with further progress of the methods, they will become competitive for automatically creating robot behaviors of interest. However, current methods are limited with respect to the (Kolmogorov) complexity of evolved behavior. Using the evolution of robot trajectories as an example, we show that by adding four features, namely (1) freezing of previously evolved structure, (2) temporal scaffolding, (3) a homogeneous transfer function for output nodes, and (4) mutations that create new pathways to outputs, to standard methods for the evolution of neural networks, we can achieve an approximately linear growth of the complexity of behavior over thousands of generations. Overall, evolved complexity is up to two orders of magnitude over that achieved by standard methods in the experiments reported here, with the major limiting factor for further growth being the available run time. Thus, the set of methods proposed here promises to be a useful addition to various current neuroevolution methods

A Bayesian approach to the estimation of maps between riemannian manifolds

Let \Theta be a smooth compact oriented manifold without boundary, embedded in a euclidean space and let \gamma be a smooth map \Theta into a riemannian manifold \Lambda. An unknown state \theta \in \Theta is observed via X=\theta+\epsilon \xi where \epsilon>0 is a small parameter and \xi is a white Gaussian noise. For a given smooth prior on \Theta and smooth estimator g of the map \gamma we derive a second-order asymptotic expansion for the related Bayesian risk. The calculation involves the geometry of the underlying spaces \Theta and \Lambda, in particular, the integration-by-parts formula. Using this result, a second-order minimax estimator of \gamma is found based on the modern theory of harmonic maps and hypo-elliptic differential operators.Comment: 20 pages, no figures published version includes correction to eq.s 31, 41, 4