Journal of Biomechanical Engineering This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Monte Carlo Type Simulations of Mineralized Collagen Fibril Based on Two Scale Asymptotic Homogenization
A multiscale model for mineralized collagen fibril (MCF) is proposed by taking into account the uncertainties associated with the geometrical properties of the mineral phase and its distribution in the organic matrix. The asymptotic homogenization approach along with periodic boundary conditions has been used to derive the effective elastic moduli of bone's nanostructure at two hierarchical length scales, namely: microfibril (MF) and MCF. The uncertainties associated with the mineral plates have been directly included in the finite element mesh by randomly varying their sizes and structural arrangements. A total of 100 rea...
Source: Journal of Biomechanical Engineering - February 13, 2019 Category: Biomedical Engineering Source Type: research

Swine Vagina Under Planar Biaxial Loads: An Investigation of Large Deformations and Tears
In this study, planar equi-biaxial tests on square specimens of vaginal tissue, with sides oriented along the longitudinal direction (LD) and circumferential direction (CD), were conducted using swine as animal model. Three groups of specimens were mechanically tested: the NT group (n  = 9), which had no pre-imposed tear, the longitudinal tear (LT) group (n  = 9), and the circumferential tear (CT) group (n  = 9), which had central pre-imposed elliptically shaped tears with major axes oriented in the LD and the CD, respectively. Through video recording during testing, axial strains were measured for the NT group...
Source: Journal of Biomechanical Engineering - February 13, 2019 Category: Biomedical Engineering Source Type: research

Mapping of Intervertebral Disk Annulus Fibrosus Compressive Properties Is Sensitive to Specimen Boundary Conditions
Predicting the mechanical behavior of the intervertebral disk (IVD) in health and in disease requires accurate spatial mapping of its compressive mechanical properties. Previous studies confirmed that residual strains in the annulus fibrosus (AF) of the IVD, which result from nonuniform extracellular matrix deposition in response to in vivo loads, vary by anatomical regions (anterior, posterior, and lateral) and zones (inner, middle, and outer). We hypothesized that as the AF is composed of a nonlinear, anisotropic, viscoelastic material, the state of residual strain in the transverse plane would influence the apparent val...
Source: Journal of Biomechanical Engineering - February 13, 2019 Category: Biomedical Engineering Source Type: research

Estimation of the Balance-Keeping Control Law Applied by a Human Being Upon a Sudden Sagittal Tilt Perturbation
This study aims to estimate the control law employed by the central nervous system (CNS) to keep a person in balance after a sudden disturbance. For this aim, several experiments were carried out, in which the subjects were perturbed sagittally by using a single-axis tilt-platform and their motions were recorded with appropriate sensors. The analysis of the experimental results leads to the contribution of this paper as a conjecture that the CNS commands the muscular actuators of the joints according to an adaptive proportional-derivative (PD) control law such that its gains and set points are updated continuously. This co...
Source: Journal of Biomechanical Engineering - February 13, 2019 Category: Biomedical Engineering Source Type: research

Erratum: “The Mechanical Role of the Radial Fibers Network Within the Annulus Fibrosus of the Lumbar Intervertebral Disc: A Finite Elements Study” [ASME J. Biomech. Eng., 2018, 141 (2), p. 021006: DOI: 10.1115/1.4041769 ]
In the paper “The Mechanical Role of the Radial Fibers Network Within the Annulus Fibrosus of the Lumbar Intervertebral Disc: A Finite Elements Study,” the affiliation of Fabio Galbusera was incorrect. The correct affiliation is “IRCCS Istituto Ortopedico Galeazzi, Milan, Italy.” (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - February 13, 2019 Category: Biomedical Engineering Source Type: research

The Path to Deliver the Most Realistic Follower Load for a Lumbar Spine in Standing Posture: A Finite Element Study
A spine is proven to be subjected to a follower load which is a compressive load of physiologic magnitude acting on the whole spine. The path of the follower load approximates the tangent to the curve of the spine in in vivo neutral standing posture. However, the specific path location of the follower load is still unclear. The aim of this study is to find out the most realistic location of the follower load path (FLP) for a lumbar spine in standing. A three-dimensional (3D) nonlinear finite element model (FEM) of lumbosacral vertebrae (L1-S1) with consideration of the calibrated material properties was established and val...
Source: Journal of Biomechanical Engineering - January 31, 2019 Category: Biomedical Engineering Source Type: research

Effect of Local Neck Anatomy on Localized One-Dimensional Measurements of Arterial Stiffness: A Finite-Element Model Study
In this study, the effect of stresses and deformations induced by the US probe, and the effect of anatomy surrounding CCA on a simulated 1D stiffness measurement (PWVus) is compared with the ground truth stiffness (PWVgt) in 60 finite-element models (FEM) derived from anatomical computed tomography (CT) scans of ten healthy male volunteers. Based on prior knowledge from the literature, and from results in this study, we conclude that it is safe to approximate arterial stiffness using 1D measurements of compliance or pulse wave velocity, regardless of boundary conditions emerging from the anatomy or from the measurement pro...
Source: Journal of Biomechanical Engineering - January 31, 2019 Category: Biomedical Engineering Source Type: research

An Inverse Dynamics Optimization Formulation With Recursive B-Spline Derivatives and Partition of Unity Contacts: Demonstration Using Two-Dimensional Musculoskeletal Arm and Gait
In this study, an inverse dynamics optimization formulation and solution procedure is developed for musculoskeletal simulations. The proposed method has three main features: high order recursive B-spline interpolation, partition of unity, and inverse dynamics formulation. First, joint angle and muscle force profiles are represented by recursive B-splines. The formula for high order recursive B-spline derivatives is derived for state variables calculation. Second, partition of unity is used to handle the multicontact indeterminacy between human and environment during the motion. The global forces and moments are distributed...
Source: Journal of Biomechanical Engineering - January 31, 2019 Category: Biomedical Engineering Source Type: research

Fundamental Roles of Axial Stretch in Isometric and Isobaric Evaluations of Vascular Contractility
Vascular smooth muscle cells (VSMCs) can regulate arterial mechanics via contractile activity in response to changing mechanical and chemical signals. Contractility is traditionally evaluated via uniaxial isometric testing of isolated rings despite the in vivo environment being very different. Most blood vessels maintain a locally preferred value of in vivo axial stretch while subjected to changes in distending pressure, but both of these phenomena are obscured in uniaxial isometric testing. Few studies have rigorously analyzed the role of in vivo loading conditions in smooth muscle function. Thus, we evaluated effects of ...
Source: Journal of Biomechanical Engineering - January 25, 2019 Category: Biomedical Engineering Source Type: research

A Synergy-Based Motor Control Framework for the Fast Feedback Control of Musculoskeletal Systems
This paper presents a computational framework for the fast feedback control of musculoskeletal systems using muscle synergies. The proposed motor control framework has a hierarchical structure. A feedback controller at the higher level of hierarchy handles the trajectory planning and error compensation in the task space. This high-level task space controller only deals with the task-related kinematic variables, and thus is computationally efficient. The output of the task space controller is a force vector in the task space, which is fed to the low-level controller to be translated into muscle activity commands. Muscle syn...
Source: Journal of Biomechanical Engineering - January 25, 2019 Category: Biomedical Engineering Source Type: research

Probing Mechanical Properties of Brain in a Tuberous Sclerosis Model of Autism
Causes of autism spectrum disorders (ASD) are understood poorly, making diagnosis and treatment challenging. While many studies have investigated the biochemical and genetic aspects of ASD, whether and how mechanical characteristics of the autistic brain can modulate neuronal connectivity and cognition in ASD are unknown. Previously, it has been shown that ASD brains are characterized by abnormal white matter and disorganized neuronal connectivity; we hypothesized that these significant cellular-level structural changes may translate to changes in the mechanical properties of the autistic brain or regions therein. Here, we...
Source: Journal of Biomechanical Engineering - January 18, 2019 Category: Biomedical Engineering Source Type: research

Multidirection Validation of a Finite Element 50th Percentile Male Hybrid III Anthropomorphic Test Device for Spaceflight Applications
The objective of this study was to validate a Hybrid III ATD FE model using a multidirection test matrix for future spaceflight configurations. Twenty-five Hybrid III physical tests were simulated using a 50th percentile male Hybrid III FE model. The sled acceleration pulses were approximately half-sine shaped, and can be described as a combination of peak acceleration and time to reach peak (rise time). The range of peak accelerations was 10 –20 G, and the rise times were 30–110 ms. Test directions were frontal (−GX), rear (GX), vertical (GZ), and lateral (GY). Simulation responses were compared to physical tests ...
Source: Journal of Biomechanical Engineering - January 18, 2019 Category: Biomedical Engineering Source Type: research

A Numerical Study of Sensitivity Coefficients for a Model of Amyloid Precursor Protein and Tubulin-Associated Unit Protein Transport and Agglomeration in Neurons at the Onset of Alzheimer's Disease
Modeling of intracellular processes occurring during the development of Alzheimer's disease (AD) can be instrumental in understanding the disease and can potentially contribute to finding treatments for the disease. The model of intracellular processes in AD, which we previously developed, contains a large number of parameters. To distinguish between more important and less important parameters, we performed a local sensitivity analysis of this model around the values of parameters that give the best fit with published experimental results. We show that the influence of model parameters on the total concentrations of amylo...
Source: Journal of Biomechanical Engineering - January 18, 2019 Category: Biomedical Engineering Source Type: research

The Effect of Textiles Impregnated With Particles With High Emissivity in the Far Infrared, on the Temperature of the Cold Hand
In engineering and medicine, there is a growing interest in using textiles made of composites with enhanced thermal properties. One such type of textile is fabric impregnated with ceramics and mineral particles. This material has high emissivity in the infrared range and may have therapeutic benefits for treatments of diseases, like Raynaud's syndrome. While there is significant clinical and commercial interest, there is an evident lack of fundamental studies on the heat transfer aspects of these fabrics. The goal of this technical brief is to present results from a fundamental study examining the thermal effects of fabric...
Source: Journal of Biomechanical Engineering - January 18, 2019 Category: Biomedical Engineering Source Type: research

The Effect of Inhomogeneous Trabecular Stiffness Relationship Selection on Finite Element Outcomes for Shoulder Arthroplasty
In conclusion, the low varia tions attributable to the selection of a trabecular stiffness relationship based on anatomic-site suggest that FE models constructed for shoulder arthroplasty can utilize an inhomogeneous site-pooled trabecular relationship without inducing marked variability in the assessed outcome measures. (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - January 18, 2019 Category: Biomedical Engineering Source Type: research