THE EFFECTS OF IMPACT AVOIDANCE TECHNIQUES ON HEAD INJURY RISK

The purpose of this study was to determine the influence of impact deflection and neck compliance on peak linear and peak angular accelerations during a front impact to a Hybrid III head using a pneumatic linear impactor. Impact deflection was done by translating the headform laterally and showed to be effective at reducing linear and angular accelerations as well as GSI. Neck compliance was altered using one Hybrid III 50th percentile neck and two modified Hybrid III necks. A less compliant neck increased linear acceleration but decreased angular acceleration. When compared to estimated injury thresholds, the results demonstrated that an increase in lateral translation or a decrease in neck compliance resulted in a significant decrease in the risk of head injury as reflected by peak linear and angular accelerations

KINEMATIC CHARACTERISTICS OF OPPOSITE-FIELD HITTING

Baseball is one of many popular sports in which the cen tral event involves a collision between an implement and a ball. It is generally agreed that hitting a baseball is one of the more difficult skills to learn in sport (Breen, 1975; Williams & Underwood, 1971). In addition to the habitual goal of maximal transfer of momentum to the ball, the batter frequently faces problems of directional guidance, due to certain strategic and mechanical requirements. The nature of the contact surfaces, the high velocity of pitched baseballs and the variety of ball trajectories combine to increase the difficulty of the task

EVALUATION OF HOCKEY HELMET PERFORMANCE BY FINITE ELEMENT MODELING

Since the advent of helmet use in ice hockey the incidence of traumatic brain injury (TBI) has decreased, however the prevalence of mild traumatic brain injury (mTBI) has not (Wennberg and Tator, 2003). Recently finite element modeling (FEM) has been used in an attempt to identify mTBI thresholds from an impact using shear stress strain (SSS) and other parameters to aid in reducing these injuries (Zhang et al., 2004). The following study employs the University College Dublin Brain Trauma Model (UCDBTM) to evaluate the ability of vinyl nitrile (VN) and expanded polypropolene (EPP) hockey helmets to reduce the risk of brain injury

THE DETERMINATION OF NOVEL IMPACT CONDITIONS FOR THE ASSESMENT OF LINEAR AND ANGULAR HEADFORM ACCELERATIONS

Sports helmets, albeit very effective at preventing traumatic brain injury, have not mitigated the risk of mild traumatic brain injury in sport (Flik, Lyman, & Marx, 2005). Current protocols utilized in sports helmet testing incorporate only impact vectors through the center of mass, eliciting primarily linear accelerations. Angular acceleration has been suggested to be a better predictor of diffuse head injury than linear acceleration (Holbourn, 1943); therefore, the objective of this study was to develop a protocol capable of producing and measuring both forms of acceleration for future implementation into sports helmet standards

THE EFFECT OF IMPACT CONDITION ON THE RELATIONSHIP BETWEEN LINEAR AND ANGULAR ACCELERATION LINEAR

Helmets are mandatory in many contact sports and are designed to prevent traumatic brain injuries. When assessing their performance, angular acceleration is not measured, as it is generally assumed to be highly correlated with linear acceleration (Pellman et al., 2003). Although being common, this assumption is not supported by strong data. The aim of this study was to establish the relationship between linear and angular acceleration

PERCEIVED DIFFERENCES IN SKATING CHARACTERISTICS RESULTING FROM THREE CROSS SECTIONAL SKATE BLADE PROFILES

The purpose of this study was to document differences in perceived skating characteristics resulting from three unique cross sectional skate blade profiles. Sixteen (n=16) University level hockey players were used in this double blind study looking at the perceived performance differences of four different skate blade profiles. No significant differences were found between skate blade profiles, preferred skate blade profile and time to complete given drills. Future research should look at different blade profiles and their interaction at ice level

Power and Strength Profiles of Elite 16-20 Years Old Ice Hockey Players

The sport of ice hockey has received considerable attention from researchers interested in the energy systems supporting high level competition. For example, Bonen and Babincau, 1977, Ferguson. Marcotte and Montpetit, 1969, and Montpetit, Ferguson and Marcotte, 1971 investigated the V02 max. of hockey players using various measurement and statistical prediction techniques. Other researchers have speculated that the nature of ice hockey requires high levels of anaerobic energy and the ability to recover quickly from a bout of high intensity exercise (Green, Bishop, Houston, McKillop, Norman and Stothart, 1976; Montpetit, Binetto and Taylor, 1969; Smith, Wenger and Quinney, Sexsmith and Steadward, 1980, Watson and Sargeant, 1986). At present, there is little evidence of attempts to correlate physiological power to mechanical power of ice hockey players. Since skating, which is central to the game of hockey, requires a great deal of leg power, this variable would seem to be a basic prerequisite of effective performance. The purpose of the present study, therefore, was to investigate power and strength relationships in elite 16-20 year old ice hockey players. More specifically, an attempt was made to describe the relationships between various anaerobic power measures and the mechanical power exhibited by the leg muscles during a vertical jump task

Spin observables of the reactions NN -> DeltaN and pd -> Delta (pp)(1S0) in collinear kinematics

A general formalism for double and triple spin-correlations of the reaction NN -> DeltaN is developed for the case of collinear kinematics. A complete polarization experiment allowing to reconstruct all of the four amplitudes describing this process is suggested. Furthermore, the spin observables of the inelastic charge-exchange reaction pd -> Delta^0(pp)(1S0) are analyzed in collinear kinematics within the single pN scattering mechanism involving the subprocess pn -> Delta^0p. The full set of spin observables related to the polarization of one or two initial particles and one final particle is obtained in terms of three invariant amplitudes of the reaction pd -> Delta (pp)(1S0) and the transition form factor d->(pp)(1S0). A complete polarization experiment for the reaction pd -> Delta^0(pp)(1S0) is suggested which allows one to determine three independent combinations of the four amplitudes of the elementary subprocess NN -> DeltaN.Comment: 12 pages, 1 figur

Microwave Current Imaging in Passive HTS Components by Low-Temperature Laser Scanning Microscopy (LTLSM)

We have used the LTLSM technique for a spatially resolved investigation of the microwave transport properties, nonlinearities and material inhomogeneities in an operating coplanar waveguide YBa_2Cu_3O_{7-\delta} (YBCO) microwave resonator on an LaAlO_3 (LAO) substrate. The influence of twin-domain blocks, in-plane rotated grains, and micro-cracks in the YBCO film on the nonuniform rf current distribution were measured with a micrometer-scale spatial resolution. The impact of the peaked edge currents and rf field penetration into weak links on the linear device performance were studied as well. The LTLSM capabilities and its future potential for non-destructive characterization of the microwave properties of superconducting circuits are discussed.Comment: 8 pages, 9 figures, 2-column format, presented at High Temperature Superconductors in High Frequency Fields 2004, Journal of Superconductivity (in press