UPPER BODY MOVEMENTS IN ELITE JAVELIN THROWS

INTRODUCTION - For an athlete to compete at an international level he will not only need the raw materials necessary for the event, but an effective training programme. That will enable him to utilise these resources to the full. It is well accepted that exercise prescription must match the mode of training to the desired effect. This is embodied in the specificity principle which states that training adaptations are specific to the cells and their structural and functional elements that are overloaded (McCafferty & Horvath, 1977).Hence, to provide training advice to the elite javelin thrower exact details of the thrower's movements during the event must be known. Otherwise, developing a training programme to fit the thrower's requirements will be impossible. It was the aim of this study to quantify the upper body movements of a group of elite javelin throwers when performing at the highest level of competition. Every throw of12 athletes competing in the men's javelin final of the 1995 World Championships were filmed and, subsequently analysed. Filming was conducted using 2 phase-locked High speed Photosonics 1PL cine cameras which were zoomed on the javelin runway such that all of the thrower's movements incorporating the last few cross-over strides, the delivery and the first few meters of the javelin6gM after release, were in full view. Calibration of this area was achieved by mounting Rflective spherical markers on a system of vertical poles that were arranged to surround a 7 m x 4 m x 3.2 m volume. Three dimensional coordinates of the markers were generated using an Elta Ill tachymeter. The films developed and the best performances of the competitors were digitised using a sys-tem developed by Bartlett (1 990) compatible with Acorn Archimedes computers. RESULTS -Analysis of the best throws by the three medallists (all over 86 m) showed that all three athletes achieved release speeds in excess of 30 m.s-I. However, the way in which each athlete achieved such a high speed was very different indeed. For example, the gold and silver medallists were found to laterally align the trunk during the delivery in a similar manner. Nevertheless, the path of the javelin grip in a lateral direction differed by 54 cm between the two athletes. Furthermore, angular velocities of the elbow joints in extension were found to range between 45.0 rad.s-I and 26.5 rad.s! Similarly the movement of the upper arm during the delivery was a combination of extension, horizontal flexion and abduction, the angular velocities of which ranged from 21.8rad.s-I to 15.6 rad.s-I. Medial rotation angular velocities were as high as 45.0 rad.s-I indicating that this also is a important contributor to the release speed of the javelin. CONCLUSIONS - These results suggest that the patterns of muscular activation or the muscles used to accelerate the javelin were very different for the three medal lists. It would therefore seem appropriate that the training programmes of each athlete should be different and designed very specifically to meet their unique movement pattern. Examining the contribution of the upper body musculature to the release speed of the javelin is an aim of future research. REFERENCES Bartlett, R.M. (1 990). A biomechanical analysisprogramme package. Unpub. Mas. Thes.McCafferty, W.B. & Horvath, S.M. (1977).Research Quarterly, 48, 358-37 1

COORDINATION VARIABILITY DURING OVERGROUND, TREADMILL AND TREADMILL-ON-DEMAND RUNNING

The purpose of this study was to investigate differences in lower extremity coordination variability between overground, treadmill and treadmill-on-demand running. A modified normalised root mean square difference technique was used to quantify the variability in lower extremity coordination calculated from the kinematic data collected during ten strides of overground, treadmill and treadmill-on-demand running at 3.5 m.s". Although no significant differences were observed between the two types of treadmill, significantly reduced (p < 0.02) coordination variability was seen in the treadmill and treadmill-ondemand conditions compared to overground locomotion. Therefore, a constant belt speed during treadmill locomotion does not account for the differences seen between overground and treadmill running and further work is required to determine factors that cause the difference

Homophily and Contagion Are Generically Confounded in Observational Social Network Studies

We consider processes on social networks that can potentially involve three factors: homophily, or the formation of social ties due to matching individual traits; social contagion, also known as social influence; and the causal effect of an individual's covariates on their behavior or other measurable responses. We show that, generically, all of these are confounded with each other. Distinguishing them from one another requires strong assumptions on the parametrization of the social process or on the adequacy of the covariates used (or both). In particular we demonstrate, with simple examples, that asymmetries in regression coefficients cannot identify causal effects, and that very simple models of imitation (a form of social contagion) can produce substantial correlations between an individual's enduring traits and their choices, even when there is no intrinsic affinity between them. We also suggest some possible constructive responses to these results.Comment: 27 pages, 9 figures. V2: Revised in response to referees. V3: Ditt

The design of organic catalysis for epoxidation by hydrogen peroxide

The potential of various organic species to catalyze epoxidation of ethene by hydrogen peroxide is explored with B3LYP/6-31G* DFT calculations

High-Order Coupled Cluster Method (CCM) Calculations for Quantum Magnets with Valence-Bond Ground States

In this article, we prove that exact representations of dimer and plaquette valence-bond ket ground states for quantum Heisenberg antiferromagnets may be formed via the usual coupled cluster method (CCM) from independent-spin product (e.g. N\'eel) model states. We show that we are able to provide good results for both the ground-state energy and the sublattice magnetization for dimer and plaquette valence-bond phases within the CCM. As a first example, we investigate the spin-half $J_1$--$J_2$ model for the linear chain, and we show that we are able to reproduce exactly the dimerized ground (ket) state at $J_2/J_1=0.5$. The dimerized phase is stable over a range of values for $J_2/J_1$ around 0.5. We present evidence of symmetry breaking by considering the ket- and bra-state correlation coefficients as a function of $J_2/J_1$. We then consider the Shastry-Sutherland model and demonstrate that the CCM can span the correct ground states in both the N\'eel and the dimerized phases. Finally, we consider a spin-half system with nearest-neighbor bonds for an underlying lattice corresponding to the magnetic material CaV$_4$O$_9$ (CAVO). We show that we are able to provide excellent results for the ground-state energy in each of the plaquette-ordered, N\'eel-ordered, and dimerized regimes of this model. The exact plaquette and dimer ground states are reproduced by the CCM ket state in their relevant limits.Comment: 34 pages, 13 figures, 2 table

The Extended Coupled Cluster Treatment of Correlations in Quantum Magnets

The spin-half XXZ model on the linear chain and the square lattice are examined with the extended coupled cluster method (ECCM) of quantum many-body theory. We are able to describe both the Ising-Heisenberg phase and the XY-Heisenberg phase, starting from known wave functions in the Ising limit and at the phase transition point between the XY-Heisenberg and ferromagnetic phases, respectively, and by systematically incorporating correlations on top of them. The ECCM yields good numerical results via a diagrammatic approach, which makes the numerical implementation of higher-order truncation schemes feasible. In particular, the best non-extrapolated coupled cluster result for the sublattice magnetization is obtained, which indicates the employment of an improved wave function. Furthermore, the ECCM finds the expected qualitatively different behaviours of the linear chain and the square lattice cases.Comment: 22 pages, 3 tables, and 15 figure

Albany: Using Component-based Design to Develop a Flexible, Generic Multiphysics Analysis Code

Abstract: Albany is a multiphysics code constructed by assembling a set of reusable, general components. It is an implicit, unstructured grid finite element code that hosts a set of advanced features that are readily combined within a single analysis run. Albany uses template-based generic programming methods to provide extensibility and flexibility; it employs a generic residual evaluation interface to support the easy addition and modification of physics. This interface is coupled to powerful automatic differentiation utilities that are used to implement efficient nonlinear solvers and preconditioners, and also to enable sensitivity analysis and embedded uncertainty quantification capabilities as part of the forward solve. The flexible application programming interfaces in Albany couple to two different adaptive mesh libraries; it internally employs generic integration machinery that supports tetrahedral, hexahedral, and hybrid meshes of user specified order. We present the overall design of Albany, and focus on the specifics of the integration of many of its advanced features. As Albany and the components that form it are openly available on the internet, it is our goal that the reader might find some of the design concepts useful in their own work. Albany results in a code that enables the rapid development of parallel, numerically efficient multiphysics software tools. In discussing the features and details of the integration of many of the components involved, we show the reader the wide variety of solution components that are available and what is possible when they are combined within a simulation capability. Key Words: partial differential equations, finite element analysis, template-based generic programmin