IMAGE-BASED MODELING AND SIMULATION OF THE SHOULDER DURING BASEBALL PITCHING

The imaged-based modeling and simulation such as the virtual, interactive, musculoskeletal system (VIMS) software provides accurate muscle orientations and their relative moment arms. An imaged-based biomechanical model of upper extremity can be used for understanding of neuromuscular control and simulation of sports activities and surgery reconstruction after injuries. The relative movement of the skeletal segments cause a change of muscle orientation and its moment arm, and then affect the role of the muscle loading during the motion. This paper reviews studies in applying three-dimensional shoulder model for investigation of the multi-joint muscle function. An image based and graphic-enhanced, quantitative model of the musculoskeletal system would be utilized for dynamic shoulder analysis with accurate muscle line of action incorporating bone movement and muscle wrapping around the joint

Charm Correlation as a Diagnostic Probe of Quark Matter

The use of correlation between two open-charm mesons is suggested to give information about the nature of the medium created in heavy-ion collisions. Insensitivity to the charm production rate is achieved by measuring normalized cumulant. The acollinearity of the D momenta in the transverse plane is a measure of the medium effect. Its dependence on nuclear size or E_T provides a signature for the formation of quark matter.Comment: 12 pages, no figure

AN ELECTROMYOGRAPHIC ANALYSIS OF WINDMILL SOFTBALL PITCH

INTRODUCTION: Windmill softball pitching is a highly skilled sport combined with coordination and explosive force. Besides many kinematic and kinetic analyses relative to it, its mechanics can also be understood through the EMG analysis of a pitcher’s leading foot and throwing arm. The purpose of this study was to investigate how the activated throwing arm and leading foot of a pitcher contribute to his strength while pitching

A PRELIMINARY STUDY OF BREAST MOVEMENT IN DIFFERENT BRA SUPPORT

To free women involved in physical activities from suffering breast pain due to insufficient breast support, thorough understanding of the breast displacement mechanism is needed. The study is aimed to determine the true movement of the breast in three types of bras, and ultimately, to build a scientific base for bra design improvement. 28 female participants were recruited and the breast movements in four different types of breast support were recorded using the electromagnetic tracking system for further analysis. The results showed that the trajectories of left and right breast in a crop-top bra for the lateral raise showed significant difference (p =.039). The effect of sportsbra was obvious in all four movements and the breast displacement decreased as the breast support level increased (from non-sportsbra to sportsbra)

KINETIC EFFECTS ON THE LOWER EXTREMITY DURING PLYOMETRIC JUMP

INTRODUCTION: Plyometric exercises are a series of cyclical activities of muscle stretch and shortening. Jumping and landing are the major movements of plyometric exercises. Previous researches reported that the plyometric training can increase the proprioception in lower extremities. It also reported that plyometric jump exercise has great assistance to increase muscle strength of lower limbs. However, a few of published researches had studied the joint loading of lower limbs in each movement of plyimetric jump. Understanding of the loading on the lower limbs is greatly helpful to decide the proper exercise prescription for the subjects who had suffered musculoskeletal injury and in the period of rehabilitation. The purpose of this study is to estimate the joint kinetics of lower limbs in depth jump

COMPARISON OF PLAYER’S CENTER OF MASS MOVEMENT BETWEEN HIGH AND LOW IMPACT POSITIONS IN TENNIS FOREHAND STROKE

During the tennis forehand stroke, the displacement of body center of mass (COM) changes with the body movement. The COM movement influences the recovery from one stroke to the next. Therefore, the purpose of this study is to investigate the differences of COM movement and joint kinematics between high and low-impact positions on different skilled players. This study adopted a 3-D motion analysis system for recording and tracing the advanced (n = 5; level 3-4) and intermediate (n = 7; level 5-6) athletes’ motion of whole body during high and low-impact positions in tennis forehand stroke. The results showed that significant difference was not found between both impact positions and level groups in ball velocity. Advanced group showed greater anterior/posterior displacement than the intermediate group in low-impact position that increased the kinetic energy

Comparison of breast motion at different levels of support during physical activity

Optical tracking systems have been used in previous studies to capture the motion of the nude breast and breasts in bras, under the assumption that no breast-bra relative movement occurred within the bra. This study compared breast and bra movement through electromagnetic tracking and optical tracking systems to determine the relative breast movement occurring with different breast support and exercise-induced breast discomfort. Total of 30 female participants (mean age: 21.5 ± 2.3 years; cup sizes: A-F) were recruited and their movement at four different levels of breast support was recorded in two motion capture systems for further analysis and comparison. Significant differences between bra and breast vertical displacement were found at all support levels during periods of intense movement (r = 0.556; p < 0.05). Because the greatest bra displacement was observed when participants wore an everyday bra and the greatest breast displacement was observed when participants wore a crop-top bra, there was evident inconsistency in bra and breast motion and a high-impact sports bra was the most effective to reduce breast movement and discomfort among the four types of bras. An electromagnetic tracking system provided direct observation of the actual movement of the breasts, and an optical tracking system enabled us to monitor bra displacement. Significant differences were observed in bra and breast displacement during the intense movements included in this study. The results bring into question the assumption made in previous studies that no relative movement occurs within a breast support garment.This study is supported by Ministry of Science and Technology grants 103-2815-C-006-037-H and 105-2410-H-006-052, TAIWAN, and OT Motion Lab, Department of Occupational Therapy, National Cheng Kung University

Quark Coalescence for Charmed Mesons in Ultrarelativistic Heavy-Ion Collisions

We investigate effects of charm-quark interactions in a Quark-Gluon Plasma on the production of $D$ and $J/\psi$ mesons in high-energy heavy-ion collisions. Employing a previously constructed coalescence model that successfully reproduces the transverse momentum ($p_T$) spectra and elliptic flow ($v_2(p_T)$) of light hadrons at RHIC from underlying light-quark distributions at the phase transition temperature $T_c$, $D$-meson and $J/\psi$ $p_T$ spectra are evaluated. For the charm-quark distributions, we consider two limiting scenarios: (i) {\em no} rescattering, corresponding to perturbative QCD spectra and (ii) {\em complete} thermalization including transverse expansion. With the $D$-meson spectra acquiring a minimal $v_2$ inherited from their light-quark content, the corresponding semileptonic decay spectra of single electrons are found to practically preserve the $v_2$ of the parent particles, exhibiting marked differences between the pQCD and thermal scenarios for $p_T\ge 1$ GeV. Likewise, the $p_T$-spectra and yields of $J/\psi$'s differ appreciably in the two scenarios.Comment: 6 pages, 4 figures, version published in PLB with updated figure

System size dependence of elliptic flows in relativistic heavy-ion collisions

The elliptic flows in both Cu+Cu and Au+Au collisions at the Relativistic Heavy Ion Collider are studied in a multi-phase transport model. For both collisions at same reduced impact parameter and minimum bias collisions, the elliptic flow of partons in Cu+Cu collisions is about a factor of three smaller than that in Au+Au collisions at same energy. The reduction factor is similar to the ratio of the sizes of the two colliding systems and is also related to the combined effects of initial energy density and spatial elliptic deformation in the two reactions. A similar system size dependence is also seen in the elliptic flow of charged hadrons from minimum bias collisions.Comment: 5 pages, 5 figures, revised version, to appear in PL