A dynamic model of the head acceleration associated with heading a soccer ball

This study develops a dynamic model of head acceleration, which incorporates physiologically related neck muscle contributions, to further the understanding of the mechanical behaviour of the head-neck system during soccer heading. An inverted pendulum is combined with a linear visco-elastic element to model the head-neck system following a half-sine input force. Model parameter values were varied to obtain agreement with previously published experimental data (Naunheimet al., 2003), and were subsequently compared to literature values. The model predicted the same mechanical angular kinematics as observed experimentally both during and post impact. The greatest acceleration was in the anterior direction at the instant the ball left the head, attributed to the elastic stiffness of the neck musculature. The head-neck stiffness and damping coefficients determined from the model (350 N m rad-1 and 4 N m s rad-1, respectively) were similar to those reported elsewhere when subjects were asked to resist maximally. The model may be subsequently used to investigate differences in technique and ability with respect to the salient model parameters to further our biomechanical understanding of soccer heading

Agricultural Interests and the Origins of Capitalism: A Parallel Comparative History of Germany, Denmark, New Zealand, and the USA

Addressing the literature on the historical origins of capitalism, this study analyses the role agriculture played in the formation of non-market economic coordination in economic and social affairs around 1900. It argues that the dominant rural production profile dictated whether farmers did exert a significant impact on socio-economic institution and policy formation outside the rural sector. By applying the method of parallel demonstration of theory, we illustrate the plausibility of these theoretical considerations through juxtaposing the historical record of Germany, Denmark, New Zealand and the USA. The article highlights the limits of a dichotomous view on the origins of capitalism because the coordination effect of rural economies varies within the later coordinated and the later liberal cluster of market economies