Effect of Mental and Physical Practice on Clinical Skill Learning in Kinesiology

Purpose: The amount of information required for an allied health professional has increased dramatically. In-class practice time and large amounts of practice materials may be difficult for instructors to acquire. Mental practice is a method of practice that does not involve physical movement or materials. This study investigated the effect of mental practice, physical practice, and a combination of mental and physical practice on kinesiology students learning three manual muscle tests. Method: Fifty-six students aged 18 to 26 years (M = 20.09, SD + 1.58), pursuing a degree in kinesiology with an emphasis in either athletic training or kinesiotherapy participated in this study. Participants underwent two days of practice that included either mental practice, physical practice, or a combination of mental and physical practice for three Manual Muscle Tests (MMTs). Approximately 48 hours later, participants completed a post-test of the MMTs that was evaluated by two trained examiners. Participants also completed a survey related to demographics, difficulty of the MMTs, and intentions for using mental practice. Results: The MMT post-test ANOVA revealed no significant learning differences between groups for all three Manual Muscle Tests. There were no significant differences in Manual Muscle Tests difficulty ratings between groups; however, there was a significant difference in participants’ difficulty ratings across the Manual Muscle Tests. A majority of participants indicated they would use mental practice in the future. Conclusions: The results indicated that kinesiology students seemed to learn equally well regardless of practice type. Utilization of mental practice in or outside of the classroom may be a strategy to supplement student learning in situations where class time and/or resources for physical skill practice may be more difficult to obtain

An optimization-based phase-field method for continuous-discontinuous crack propagation

This is the peer reviewed version of the following article: This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Geelen, R., Liu, Y., Dolbow, J., Rodriguez-Ferran, A. An optimization-based phase-field method for continuous-discontinuous crack propagation. "International journal for numerical methods in engineering", 5 Octubre 2018, vol. 116, núm. 1, p. 1-20, which has been published in final form at https://onlinelibrary.wiley.com/doi/abs/10.1002/nme.5911.A new continuous-discontinuous strategy for the computational modeling of crack propagation within the context of phase-field models of fracture is presented. The method is designed to introduce and update a sharp crack surface within an evolving damage band, and to enhance the kinematics of the finite element approximation accordingly. The proposed approach relies on three key elements. First, we propose the use of a crack length functional to provide a trigger for initiating a continuous to discontinuous transition. Next, the crack path identification is addressed by introducing the concept of an auxiliary damage field that varies with an extension of the sharp crack surface. The sharp crack surface is extended through an optimization algorithm, in which the difference between the auxiliary field and the actual damage field stemming from the phase-field framework is minimized. Finally, a strong discontinuity is inserted in the wake of the diffuse crack tip with the eXtended Finite Element Method (X-FEM), completing the continuous to discontinuous transition. Several benchmark problems in two-dimensional quasi-static fracture mechanics are presented to demonstrate the accuracy and robustness of the method.Peer ReviewedPostprint (author's final draft

Energy consistent framework for continuously evolving 3D crack propagation

This paper presents a formulation for brittle fracture in 3D elastic solids within the context of configurational mechanics. The local form of the first law of thermodynamics provides a condition for equilibrium of the crack front. The direction of the crack propagation is shown to be given by the direction of the configurational forces on the crack front that maximise the local dissipation. The evolving crack front is continuously resolved by the finite element mesh, without the need for face splitting or the use of enrichment techniques. A monolithic solution strategy is adopted, solving simultaneously for both the material displacements (i.e. crack extension) and the spatial displacements, is adopted. In order to trace the dissipative loading path, an arc-length procedure is developed that controls the incremental crack area growth. In order to maintain mesh quality, smoothing of the mesh is undertaken as a continuous process, together with face flipping, node merging and edge splitting where necessary. Hierarchical basis functions of arbitrary polynomial order are adopted to increase the order of approximation without the need to change the finite element mesh. Performance of the formulation is demonstrated by means of three representative numerical simulations, demonstrating both accuracy and robustness.Comment: 35 pages, 17 figure

Impact of Prolonged Sitting on Peripheral and Central Vascular Health

Prolonged, uninterrupted sitting negatively impacts markers of peripheral vascular health, particularly, vasodilatory function of leg arteries. Whether sitting can similarly impact measures of central vascular health, as well as overall leg vasoreactivity (i.e.,vasodilatory and vasoconstrictor function) remains unknown. To address this, measurements were made in relatively healthy participants (i.e., free of overt disease; n=20, age=26 § 7; body mass index = 30 § 7 kg/m2; 7 female) pre, during and post 3 hours of uninterrupted sitting. Measures of central vascular health included arterial wave reflection(augmentation index and Reflection Magnitude — RM%) and aortic vascular stiffness (aortic pulse velocity). Local vasoreactivity of the distal, posterior tibial artery was measured using flow-mediated dilation — FMD, coupled with low-flow mediated constriction, and microvascular function was assessed through the total hyperemic blood velocity (area-under-curve)response during FMD. After sitting, there was a significant increase in aortic pulse wave velocity (pre sit = 5.7 § 0.3 vs post sit = 6.1 § 0.3 m/s;p=0.009, d = 0.36), whereas, augmentation index decreased (pre sit = 13 § 3 vs post sit = 3 § 1%; p < 0.001, d = 0.71). Albeit a moderate effect for decrease, RM% was not significantly altered during sitting (p = 0.13, d = 0.3). Vasodilatory (i.e., FMD pre sit = 0.5 § 0.04 vs post sit =0.3 § 0.04 mm; p = 0.014, d = 0.29) and microvascular function (i.e., Microvascular area-under-curve: pre sit = 2,196 § 333 vs 1,157§172 AU; p = 0.003, d = 0.31) decreased, but vasoconstrictor function (low-flow mediated constriction; p = 0.85, d = 0.005) was unaffected by sitting. In conclusion, these data demonstrate that a prolonged bout of unin- terrupted sitting negatively impacts markers of peripheral and central vascular health in relatively healthy adults

Mathematical models of supersonic and intersonic crack propagation in linear elastodynamics

This paper presents mathematical models of supersonic and intersonic crack propagation exhibiting Mach type of shock wave patterns that closely resemble the growing body of experimental and computational evidence reported in recent years. The models are developed in the form of weak discontinuous solutions of the equations of motion for isotropic linear elasticity in two dimensions. Instead of the classical second order elastodynamics equations in terms of the displacement field, equivalent first order equations in terms of the evolution of velocity and displacement gradient fields are used together with their associated jump conditions across solution discontinuities. The paper postulates supersonic and intersonic steady-state crack propagation solutions consisting of regions of constant deformation and velocity separated by pressure and shear shock waves converging at the crack tip and obtains the necessary requirements for their existence. It shows that such mathematical solutions exist for significant ranges of material properties both in plane stress and plane strain. Both mode I and mode II fracture configurations are considered. In line with the linear elasticity theory used, the solutions obtained satisfy exact energy conservation, which implies that strain energy in the unfractured material is converted in its entirety into kinetic energy as the crack propagates. This neglects dissipation phenomena both in the material and in the creation of the new crack surface. This leads to the conclusion that fast crack propagation beyond the classical limit of the Rayleigh wave speed is a phenomenon dominated by the transfer of strain energy into kinetic energy rather than by the transfer into surface energy, which is the basis of Griffiths theory