Correlation of Kinematics and Kinetics of Changing Sagittal Plane Body Position during Landing and the Risk of Non-Contact Anterior Cruciate Ligament Injury

Anterior cruciate ligament (ACL) injury is one of the most common knee injuries that negatively affect athletes’ future performance and return to play. The purpose of this study was to examine the correlation of kinematics and kinetics of changing sagittal plane body position during landing and the risk of non-contact ACL injury. Seven university female (age 19.57 ± 0.79 y, height 164.21 ± 8.11 m, weight 60.43 ± 5.99 kg) athletes playing soccer and handball, and with ≥ two years of training volunteered for this research. Three trunk positions: Lean Forward Landing (LFL), Self-selected Landing (SSL), and Upright Landing (URL)—via double/single-leg landing—were captured by a high-speed VICON motion capture system. A 3 × 2 two-way within-subjects ANOVA and Multiple Bonferroni corrected pairwise were used to test for condition (LFL, SSL, URL) and task (single/double-leg) effects (p≤ 0.05). The findings indicated that landing with a deeper knee flexion angle (LFL) would lead to smaller impact forces when compared to upright landing.

Numerical Assessment of the Performance of Elastic Cloaks for Transient Flexural Waves

A relevant application of transformation elastodynamics has shown that flexural waves in a Kirchhoff-Love plate can be diverted and channeled to cloak a region of the ambient space. To achieve the goal, an orthotropic meta-structural plate should be employed. However, the corresponding mathematical transformation leads to the presence of an unwanted strong compressive prestress, likely beyond the buckling threshold of the structure, with a set of in-plane body forces to warrant equilibrium. In addition, the plate must possess, at the same time, high bending stiffnesses, but a null twisting rigidity. With the aim of estimating the performance of cloaks modelled with approximate parameters, an in-house finite element code, based on a subparametric technique, is implemented to deal with the cloaking of transient waves in orthotropic thin plates. The tool allows us to explore the sensitivity of specific stiffness parameters that may be difficult to match in a real cloak design. In addition, the finite element code is extended to investigate a meta-plate interacting with a Winkler foundation, to confirm how the subgrade modulus should transform in the cloak region.

Influence of the material microstructural properties on a 3-point bending test

The purpose of this study is to highlight the role played by some important factors on sprinback phenomenon. This latter affects significantly the geometry of the manufactured product. Large automotive or plane body parts are specifically affected by this phenomenon which complicates the tools design. The study focuses here on specific materials with high trend to develop heterogeneous strains during forming processes. Due to its hexagonal crystalline structure, titanium has initial heterogeneous microstructure that grows stronger when plastic strain occurs. Heterogeneous microstructures induce the coexistence in the material of volumes with different mechanical properties even, in some case, with different mechanical behaviours. Therefore, accommodation between these volumes generates distributed internal stresses and important elastic energy storage. The macroscopic behaviour can be provided either by average phenomenological constitutive equation identical for all locations in the material or by integrating a set of local constitutive relations taking into account the variability of the behaviour as a function of the position in the material. In this context, experimental and numerical studies of a 3-point bending test on titanium alloy are considered.

ERRATUM of Issue 213 JNMA 2018

The online version of the “Estimation of body height from head length among dental students of a dental college”(Manandhar B, Shrestha R. Estimation of body height from head length among dental students of a dental college. J Nepal Med Assoc. 2018 Feb;56(213):861-5) has been updated according to the respective authors’ reply published in JNMA 216 Issue.The following lines were found to be missing in methods section below sample size calculation: The head length was measured with the help of spreading caliper from glabella to inion when the student was sitting in a chair in a relaxed state. Glabella is the most prominent point on the frontal bone above the root of the nose. Inion is the most prominent point on external occipital protuberance on head in mid-sagittal plane. Body height was measured with the help of a standard height measuring instrument as the vertical distance from vertex to the floor with the student standing barefoot, erect, on an even floor in the Frankfurt’s Horizontal Plane. Vertex is the highest point on the head in mid-sagittal plane.