Journal of Mechanics in Medicine and Biology

A forward trunk lean sometimes occurs to compensate for quadriceps muscle weakness. Since muscle weakness in the lower extremities is commonly observed in the elderly, quadriceps weakness may trigger age-related postural change. The objective of this study was to ascertain the association between forward trunk lean during walking and musculoskeletal strength in females aged between 46 and 79 years. Musculoskeletal functions (range of joint motion, degree of kyphosis, muscle strength) and joint moments during walking were measured for 13 females. Subjects who showed greater joint moments during walking tended to lean more. Moderate association was seen between mean trunk angle during walking and knee extension moment (r = 0.535, p = 0.060). There was no statistically significant correlation between the strength of the quadriceps muscle and the mean trunk angle in walking subjects (r = 0.095, p = 0.758). These observations suggested that muscle weakness in the quadriceps is largely independent of leaning of the trunk for this sample of subjects. Other factors may change the posture to a stoop, such as severe thoracic kyphosis, poor balance control, or fear of falling.

A theoretical model for corneal swelling with respect to aqueous inflow, based on corneal dimensions and mechanical and chemical properties, is presented in this paper. The mechanical properties of the corneal stroma, with respect to aqueous inflow, are considered in the basis of swelling mechanics. Equations describing the time course of swelling are also given. With this formulation, we can explain how glaucoma may result if outflow facility decreases faster compared to aqueous inflow. The opposite situation, e.g. of hypotony, may also be considered.

Deep tendon reflex is fundamental for a neurological examination. A hyperactive reflex response is correlated with spasticity, which can also be associated with the degree of damage to the supraspinal input, essentially assessing the severity of traumatic brain injury. Clinical evaluation of the myotatic stretch reflex is provided by the National Institute of Neurological Disorders and Stroke (NINDS) Myotatic Reflex Scale (0 to 4); however, the results of the NINDS Myotatic Reflex Scale vary in terms of interpretation and lack temporal data. Deep tendon reflex can assess the severity and degree of peripheral neuropathy. Subsequent to the neurological examination, suspect patients are often referred to a specialist for definitive electrodiagnostic testing. A study by Cocito found that 28% of the prescriptions for testing were considered to be inappropriate. Therefore, the solution is a fully quantified tendon reflex evaluation system. The input force of the reflex hammer is derived from a predetermined potential energy setting. Tandem wireless three-dimensional (3D) microelectromechanical systems (MEMS) accelerometers quantify the output and latency time of the reflex. The wireless 3D MEMS accelerometers are positioned to a standard anchor point near the ankle and reflex hammer swing arm. Reflex response is quantified by the maximum and minimum components of the acceleration profile. The temporal disparity between hammer strike and response defines the latency of the reflex loop. The quantified data collected from wireless 3D MEMS accelerometers are conveyed to a portable computer. Enclosed are the initial test and evaluation and the description of such a device, which quantitatively evaluates the reflex response and latency using wireless 3D MEMS accelerometers, while demonstrating precision for reproducibility.

This paper deals with a theoretical investigation of the peristaltic transport of a physiological fluid in a porous asymmetric channel under the action of a magnetic field. The stream function, pressure gradient, and axial velocity are studied by using appropriate analytical and numerical techniques. Effects of different physical parameters such as permeability, phase difference, wave amplitude and magnetic parameter on the velocity, pumping characteristics, streamline pattern, and trapping are investigated with particular emphasis. The computational results are presented in graphical form. The results are found to be in perfect agreement with those of a previous study carried out for a nonporous channel in the absence of a magnetic field.

Biocomposites such as bone exhibit synergistic superior mechanical properties compared to its constituents, protein (collagen) and mineral (hydroxyapatite). The importance of properties of constituents at the submicron scale with regard to the toughness and strength of bone is investigated employing a discrete lattice model. The results show that matrix failure as opposed to platelet breakage provides better toughness to the bone. There is a fairly sudden increase in the toughness of bone when the strength of mineral platelet to that of protein crosses a particular critical value. These could provide clues to the preparation of ultra-tough artificial composites and the treatment of diseases related to fragility of bone.

In this work, detection of pulmonary abnormalities carried out using flow-volume spirometry and combined neural network is presented. The respiratory data (N = 225) were obtained from volunteers using a commercially available spirometer recorded by a standard acquisition protocol. The spirometric data were used for classification of normal, restrictive, and obstructive abnormalities using combined neural networks. The first level of the networks was implemented to assess the primary abnormality, whereas the second level of the networks further classified the degree of abnormality. The results were validated with the measured values of accuracy, sensitivity, specificity, and adjusted accuracy. Combined neural networks using a radial basis algorithm were found to be effective in classifying various degrees of abnormalities as normal, restrictive, or obstructive. Furthermore, combined neural networks achieved significant improvement in accuracy compared to stand-alone neural networks. It appears that this method of integrated assessment is useful in understanding pulmonary function dynamics with incomplete data and/or data with poor recording.

Heart murmurs are often the first signs of pathological changes of the heart valves, and are usually found during auscultation in primary health care. Many pathological conditions of the cardiovascular system cause murmurs and aberrations in heart sounds. Phonocardiography provides the clinician with a complementary tool to record the heart sounds heard during auscultation. The advancement of intracardiac phonocardiography, combined with modern digital processing techniques, has strongly renewed researchers' interest in studying heart sounds and murmurs. This paper presents an algorithm for the detection of heart sounds (the first and second sounds, S1 and S2) and heart murmurs. The segmentation algorithm, which separates the heart signal (or the phonocardiogram (PCG) signal), is based on the normalized average Shannon energy of the PCG signal. This algorithm makes it possible to isolate individual sounds (S1 or S2) and murmurs to give an assessment of their average duration.

The oscillatory flow of micropolar fluid in an annular region with constriction, provided by variation of the outer tube radius, is investigated. It is assumed that the local constriction varies slowly over the cross-section of the annular region. The nonlinear governing equations of the flow are solved using a perturbation method to determine the flow characteristics. The effect of micropolar fluid parameters on mean flow and pressure variables is presented.