MECHANICAL MODEL FOR DETERMINING BASE RUNNING SPEED OF SOFTBALL PLAYERS

INTRODUCT10N -Speed on the bases is critical for fast pitch softball players. A mechanical model of critical features contributing to this speed is important for both the coach and athlete for success. The purpose of this study was to develop a model and determine which variables the coach could manipulate to enhance the success of the players. METHODS• Hat (1993) proposed a deterministic model for sprinting. Average speed was determined by stride length (SL) and stride frequency (SF). SL was further divided into takeoff distance, flight distance, and landing distance with mechanical variables which contribute to these distances supporting SL. SF was also further divided into stride time and additional mechanical variables. Our model incorporated these variables and included variables related to the physical characteristics of the subjects which could be manipulated by the athlete coach. Thirty-nine female NAIA and Division 11 softball players served as subjects. RESULTS -A database was created to determine the demographics of the population selected and of the preliminary data for the proposed model. The data in the table 00low represents the demographics of the population. The data were used 10 support our model and develop a practical approach to enhancing speed of a softball player. Hay, J.G. (1993). The Biomechanics of Sport Techniques. New Jersey: PrenliceHall, pp. 396-422 (Track and fjeld: Running)

FACTORS CONTRIBUTING TO SOFTBALL PLAYERS BASE RUNNING SPEED

INTRODUCTION • The fast pitch softball player relies on speed to reach a base successfully. The purpose of this study was to determine the mechanical variables which contribute to the success of the player on the base paths. METHODS -Thirty-nine female NAIA and Division 11 softball players served as subjects. Subjects were tested with a battery attests based on the theoretical model proposed earlier. Subjects were also videotaped in the sagittal view running from home plate to first base. The video images were captured, transformed, smoothed, and graphed with the Arie! Performance Analysis System (APAS). Data were statistically determined with regression analysis to determine which variables would predict speed. RESULTS • The dependent variable was fly 40 time and the independent variables age, wgt, hgt, percent body fat, sit and reach, sit-ups, leg press, stat 40 times, stride length. cog displacement x, trunk inc1ination, and angular displacement at the hip, knee, and ankle. The demographie data were presented previously. The kinematic data are displayed in the table below The variable with the highest regression coefficient to the fly 40 times was leg press (r=.8692). Stat 40 time was highly correlated to fly 40 times (r=.7354). CONCLUSIONS• The kinematic variables selected did not aid in the prediction process. Because of this the model may be revised and/or different variables selected for interpretation

Effective Grain Orientation Mapping of Complex and Locally Anisotropic Media for Improved Imaging in Ultrasonic Non-Destructive Testing

Imaging defects in austenitic welds presents a significant challenge for the ultrasonic non-destructive testing community. Due to the heating process during their manufacture, a dendritic structure develops, exhibiting large grains with locally anisotropic properties which cause the ultrasonic waves to scatter and refract. When basic imaging algorithms, which typically make constant wave speed assumptions, are applied to datasets arising from the inspection of these welds, the resulting defect reconstructions are often distorted and difficult to interpret correctly. However, knowledge of the underlying spatially varying material properties allows correction of the expected wave travel times and thus results in more reliable defect reconstructions. In this paper, an approximation to the underlying, locally anisotropic structure of the weld is constructed from ultrasonic time of flight data. A new forward model of wave front propagation in locally anisotropic media is presented and used within the reversible-jump Markov chain Monte Carlo method to invert for the map of effective grain orientations across different regions of the weld. This forward model and estimated map are then used as the basis for an advanced imaging algorithm and the resulting defect reconstructions exhibit a significant improvement across multiple flaw characterization metrics

A Maximum Eigenvalue Approximation for Crack-Sizing Using Ultrasonic Arrays

Ultrasonic phased array systems are becoming increasingly popular as tools for the inspection of safety-critical structures with in the non-destructive testing industry. The datasets captured by these arrays can be used to image the internal microstructure of individual components, all owing the location and nature of any defects to be deduced. Unfortunately, many of the current imaging algorithms require an arbitrary threshold at which the defect measurements can be taken and this aspect of subjectivity can lead to varying characterisations of a flaw between different operators. This paper puts forward an objective approach based on the Kirchoff scattering model and the approximation of the resulting scattering matrices by Toeplitz matrices. A mathematical expression relating the crack size to the maximum eigenvalue of the associated scattering matrix is thus derived. The formula is analysed numerically to assess its sensitivity to the system parameters and it is shown that the method is most effective for sizing defects that are commensurate with the wavelength of the ultrasonic wave (or just smaller than. The method is applied to simulated FMC data arising from finite element calculations where the crack length to wavelength ratios range between 0.6 and 1.8. The recovered objective crack size exhibits an error of 12%

A spectral method for sizing cracks using ultrasonic arrays

Ultrasonic phased array systems are becoming increasingly popular as tools for the inspection of safety-critical structures within the non-destructive testing industry. The datasets captured by these arrays can be used to image the internal structure of individual components, allowing the location and nature of any defects to be deduced. Although there exist strict procedures for measuring defects via these imaging algorithms, sizing flaws which are smaller than two wavelengths in diameter can prove problematic and the choice of threshold at which the defect measurements are made can introduce an aspect of subjectivity. This paper puts forward a completely objective approach specific to cracks based on the Kirchhoff scattering model and the approximation of the resulting scattering matrices by Toeplitz matrices. A mathematical expression relating the crack size to the maximum eigenvalue of the associated scattering matrix is derived. Analysis of this approximation shows that the method will provide a unique crack size for a given maximum eigenvalue whilst providing a quick calculation method which avoids the need to numerically generate model scattering matrices (the computation time is up to 10^3 times faster). A sensitivity analysis demonstrates that the method is most effective for sizing defects that are commensurate with or smaller than the wavelength of the ultrasonic wave. The method is applied to simulated FMC data arising from finite element calculations where the crack length to wavelength ratios range between 0.6 and 1.9. The recovered objective crack size exhibits an error of 12%

The detection of flaws in austenitic welds using the decomposition of the time reversal operator

The non-destructive testing of austenitic welds using ultrasound plays an important role in the assessment of the structural integrity of safety critical structures. The internal microstructure of these welds is highly scattering and can lead to the obscuration of defects when investigated by traditional imaging algorithms. This paper proposes an alternative objective method for the detection of flaws embedded in austenitic welds based on the singular value decomposition of the time-frequency domain response matrices. The distribution of the singular values is examined in the cases where a flaw exists and where there is no flaw present. A lower threshold on the singular values, specific to austenitic welds, is derived which, when exceeded, indicates the presence of a flaw. The detection criterion is successfully implemented on both synthetic and experimental data. The datasets arising from welds containing a flaw, are further interrogated using the decomposition of the time reversal operator (DORT) method and the total focussing method (TFM) and it is shown that images constructed via the DORT algorithm typically exhibit a higher signal to noise ratio than those constructed by the TFM algorithm

Contribution of Surface Leaf-Litter Breakdown and Forest Composition to Benthic Oxygen Demand and Ecosystem Respiration in a South Georgia Blackwater River

Many North American blackwater rivers exhibit low dissolved O2 (DO) that may be the result of benthic respiration. We examined how tree species affected O2 demand via the quantity and quality of litter produced. In addition, we compared areal estimates of surface leaf-litter microbial respiration to sediment O2 demand (SOD) and ecosystem respiration (ER) in stream and swamp reaches of a blackwater river to quantify contributions of surface litter decomposition to O2 demand. Litter inputs averaged 917 and 678 g m−2 y−1 in the swamp and stream, respectively. Tree species differentially affected O2 demand via the quantity and quality of litter produced. Bald cypress (Taxodium distichum) contributed most litter inputs because of its dominance and because it produced more litter per tree, thereby making greater relative contributions to O2 demand in the swamp. In the stream, water oak (Quercus nigra) produced litter supporting lower fungal biomass and O2 uptake rates, but produced more litter than red maple (Acer rubrum). Breakdown rates in the swamp were faster, whereas standing stock decreases were lower than in the stream, indicating greater organic matter retention. Surface litter microbial respiration accounted for 89% of SOD (6.37 g O2 m−2 d−1), and 57 to 89% of ER in the swamp. Our findings suggest that surface litter drives the majority of O2 demand in some blackwater swamps, and tree species with higher rates of litterfall may make larger contributions to ER. Forested swamps may be hotspots of O2 demand in blackwater rivers because low water velocities enhance retention

Defect imaging using sub-sampled array data with least squares migration

In ultrasonic phased array imaging, if the array element spacing is greater than half the wavelength, unwanted artefacts known as grating lobes can become prevalent and obscure signals arising from physical targets. This is problematic as use of dense, periodic arrays can result in large quantities of data and an acquisition time that is too lengthy for some applications. Thus, imaging algorithms which can act on sparsely collected data whilst retaining good image quality are highly desirable. Here we apply, for the first time to our knowledge, Least-Squares Migration (LSM), an imaging methodology originating within the seismology community, to sub-sampled ultrasonic array data, resulting in the attenuation of unwanted grating lobes. It is also shown that LSM can be used to obtain improved lateral resolution compared to that achieved by the Total Focusing Method, the current standard in ultrasonic NDT imaging

Epratuzumab (humanised anti-CD22 antibody) in primary Sjögren's syndrome: an open-label phase I/II study

This open-label, phase I/II study investigated the safety and efficacy of epratuzumab, a humanised anti-CD22 monoclonal antibody, in the treatment of patients with active primary Sjögren's syndrome (pSS). Sixteen Caucasian patients (14 females/2 males, 33–72 years) were to receive 4 infusions of 360 mg/m(2 )epratuzumab once every 2 weeks, with 6 months of follow-up. A composite endpoint involving the Schirmer-I test, unstimulated whole salivary flow, fatigue, erythrocyte sedimentation rate (ESR), and immunoglobulin G (IgG) was devised to provide a clinically meaningful assessment of response, defined as a ≥20% improvement in at least two of the aforementioned parameters, with ≥20% reduction in ESR and/or IgG considered as a single combined criterion. Fourteen patients received all infusions without significant reactions, 1 patient received 3, and another was discontinued due to a mild acute reaction after receiving a partial infusion. Three patients showed moderately elevated levels of Human anti-human (epratuzumab) antibody not associated with clinical manifestations. B-cell levels had mean reductions of 54% and 39% at 6 and 18 weeks, respectively, but T-cell levels, immunoglobulins, and routine safety laboratory tests did not change significantly. Fifty-three percent achieved a clinical response (at ≥20% improvement level) at 6 weeks, with 53%, 47%, and 67% responding at 10, 18, and 32 weeks, respectively. Approximately 40%–50% responded at the ≥30% level, while 10%–45% responded at the ≥50% level for 10–32 weeks. Additionally, statistically significant improvements were observed in fatigue, and patient and physician global assessments. Further, we determined that pSS patients have a CD22 over-expression in their peripheral B cells, which was downregulated by epratuzumab for at least 12 weeks after the therapy. Thus, epratuzumab appears to be a promising therapy in active pSS, suggesting that further studies be conducted

A probabilistic approach to modelling ultrasonic shear wave propagation in locally anisotropic heterogeneous media

This article considers the propagation of a high-frequency time harmonic, elastic wave in a spatially heterogeneous, randomly layered material. The material is locally anisotropic, and the material properties change from one layer to the next by a random rotation of the associated slowness surface in the plane of wave propagation. The layer thicknesses and this rotation follow a stochastic (Markovian) process. This situation is found in ultrasonic wave propagation in polycrystalline materials; for example, in the ultrasonic non-destructive testing of welds and additively manufactured metallic components. This work focuses on monochromatic shear waves propagating in a two-dimensional plane. Using the differences in length scales between the ultrasound wavelength, the mean layer size, and the wave propagation distance, a small parameter is identified in the stochastic differential equation that emerges. Its infinitesimal generator leads to a Fokker-Planck equation via limit theorems involving this small parameter. A weak form of the Fokker-Planck equation is derived and then solved via a finite element package. The numerical solution to the Fokker-Planck equation is used to compute statistical moments of the power transmission coefficient. Finally, a parametric study on the effect of the degree of anisotropy (asphericity of the slowness surface) of the material on the transmitted energy is performed