Individual and contextual predictors of retention in Special Olympics for youth with intellectual disability: who stays involved?

BACKGROUND: Despite the recognised benefits of sport, participation is often reported to be low for youth with intellectual disability (ID). The current study was the first to longitudinally examine sport retention in this population, a critical aspect of ensuring participation. METHODS: Study participants were parents/caregivers of athletes with ID involved in community Special Olympics (SO), 11-22 years of age (N = 345). Participants completed an online survey in 2012 that included caregiver demographic and athlete intrapersonal, interpersonal and broader contextual variables. Retention rates for 2019 were determined using the SO provincial registration lists. RESULTS: Of the 345 survey participants, 81.7% remained active athletes in 2019. Caregiver demographic and athlete intrapersonal factors were largely unrelated to retention. In contrast, retention was associated with the frequency and number of sports athletes participated in, the perceived psychosocial gains of SO involvement and the environmental supports that were available to facilitate participation; frequency of sport participation was the strongest predictor of remaining a registered athlete. CONCLUSIONS: This study has implications for future initiatives aimed at increasing sport retention in a population that struggles to be engaged in sport. Efforts should focus on the athlete experience and sport-specific factors. Coaches and caregivers can foster positive experiences and play an important role in continued sport participation.

The architecture of active zone material at the frog's neuromuscular junction.

Active zone material at the nervous system's synapses is situated next to synaptic vesicles that are docked at the presynaptic plasma membrane, and calcium channels that are anchored in the membrane. Here we use electron microscope tomography to show the arrangement and associations of structural components of this compact organelle at a model synapse, the frog's neuromuscular junction. Our findings indicate that the active zone material helps to dock the vesicles and anchor the channels, and that its architecture provides both a particular spatial relationship and a structural linkage between them. The structural linkage may include proteins that mediate the calcium-triggered exocytosis of neurotransmitter by the synaptic vesicles during synaptic transmission.

Automatic acquisition of fiducial markers and alignment of images in tilt series for electron tomography.

Three-dimensional reconstruction of a section of biological tissue by electron tomography requires precise alignment of a series of two-dimensional images of the section made at numerous successive tilt angles. Gold beads on or in the section serve as fiducial markers. A scheme is described that automatically detects the position of these markers and indexes them from image to image. The resulting set of position vectors are arranged in a matrix representation of the tilt geometry and, by inversion, alignment information is obtained. The scheme is convenient, requires little operator time and provides an accuracy of < 2 pixels RMS. A tilt series of 60-70 images can be aligned in approximately 30 min on any modern desktop computer.

Dissection of active zones at the neuromuscular junction by EM tomography.

We used EM tomography to examine the fine structure of the apparently amorphous electron dense material that is seen at active zones of axon terminals when viewed by conventional 2D electron microscopy. Serial 1-nm optical slices from 3D reconstructions of individual thin tissue sections reveal that the material is composed of an interconnecting network of elongate components directly linked to synaptic vesicles and the presynaptic membrane. Each vesicle at the active zone that lies adjacent to the presynaptic plasma membrane has several such connections. Information provided by reconstruction data may be useful in generating experiments aimed at understanding the mechanisms involved in the docking of synaptic vesicles and their exocytosis during synaptic transmission.

Extensile triradiate approach for complex acetabular reconstruction in total hip arthroplasty.

The triradiate approach as described by Mears has been used for open reduction of complex dual-column acetabular fractures. Mears extended the anterior limb of this incision to the symphysis pubis by the ilioinguinal approach. From a consecutive series of 43 total hip revisions, this approach was used successfully in seven cases in which extensile exposure was necessary to revise complicated acetabular reconstructions for arthroplasty. The approach was used also to perform complex acetabular reconstruction after en bloc tumor resection. Three patients had severe intrapelvic component protrusio and anterior column deficiency where close proximity of the prosthesis and femoral neurovascular bundle were detected before surgery. Massive allograft and pelvic reconstructions were used to span large anterior column defects and to stabilize pelvic dehiscence. Complications included one hip dislocation and one posterior flap tip necrosis. Follow-up ranged from six to 34 months. No graft failure has been noted.

Biodynamic model of a parachutist.

A three-dimensional, gross-motion, finite-segment model of a parachutist is presented. The model is a modification of the UCIN Crash Victim Simulation Code. It is designed for study and analysis of the effects of opening shock and wind loading on the dynamics of a parachutist. The model consists of 11 rigid bodies linked together to simulate the human figure of a parachutist. Springs and dampers are used to model the joint forces and moments. The parachute forces are modelled by riser forces applied to the torso of the model. The wind loading is modelled as a profile drag force on each body of the model. The governing dynamical equations of motion for the system are coded into a computer program and they are then integrated numerically. Comparison with experimental data on parachutist head acceleration shows good agreement between model and experiment.

Comprehensive, three-dimensional head-neck model for impact and high-acceleration studies.

A three-dimensional, 54-degree-of-freedom computer model of the head/neck system is presented and discussed. The model consists of nine rigid bodies representing the head and vertebrae together with a series of nonlinear springs and dampers modelling the soft tissue. The soft tissue modelling involves the discs, muscles, and ligaments. The discs are modelled as two-parameter viscoelastic solids; the muscles are also modelled as two-parameter viscoelastic solids, but only able to exert force in tension; and the ligaments are modelled as nonlinear elastic bands exerting force only in tension. Equations of motion are written for this model by using Lagrange's form of d'Alembert's principle, a virtual work type principle. Computer algorithms are written to efficiently compute the numerical coefficients of these equations. The equations are integrated numerically for a number of specific cases where experimental data are available. Results show excellent agreement between the model and the experiments.