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Central nervous system (CNS) uses vision, vestibular, and somatosensory information to maintain body stability. Research has shown that there is more lumbar proprioception error among low back pain (LBP) individuals as compared to healthy people. In this study, two groups of 20 healthy people and 20 non-specific low back pain (NSLBP) participants took part in this investigation. This investigation focused on somatosensory sensors and in order to alter proprioception, a vibrator (frequency of 70 Hz, amplitude of 0.5 mm) was placed on the soleus muscle area of each leg and two vibrators were placed bilaterally across the lower back muscles. Individuals, whose vision was occluded, were placed on two surfaces (foam and rigid) on force plate, and trunk angles were recorded simultaneously. Tests were performed in eight separate trials; the independent variables were vibration (four levels) and surface (two levels) for within subjects and two groups (healthy and LBP) for between subjects (4 × 2 × 2). MANOVA and multi-factor ANOVA tests were done. Linear parameters for center of pressure (COP) [deviation of amplitude, deviation of velocity, phase plane portrait (PPP), and overall mean velocity] and non-linear parameters for COP and trunk angle [recurrence quantification analysis (RQA) and Lyapunov exponents] were chosen as dependent variables. Results indicated that NSLBP individuals relied more on ankle proprioception for postural stability. Similarly, RQA parameters for the COP on both sides and for the trunk sagittal angle indicated more repeated patterns of movement among the LBP cohort. Analysis of short and long Lyapunov exponents showed that people with LBP caused no use of all joints in their bodies (non-flexible), are less stable than healthy subjects. ispartof: FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY vol:8 ispartof: location:Switzerland status: published

Central nervous system (CNS) uses vision, vestibular, and somatosensory information to maintain body stability. Research has shown that there is more lumbar proprioception error among low back pain (LBP) individuals as compared to healthy people. In this study, two groups of 20 healthy people and 20 non-specific low back pain participants (LBP) took part in this investigation. This investigation focused on somatosensory sensors and in order to alter proprioception, a vibrator (frequency of 70Hz, amplitude of 0.5 mm) was placed on the soleus muscle area of each leg and two vibrators were placed bilaterally across the lower back muscles. Individuals, whose vision was occluded, were placed on two surfaces (foam and rigid) on force plate, and trunk angles were recorded simultaneously. Tests were performed in 8 separate trials; the independent variables were vibration (4 levels) and surface (2 levels) for within subjects and 2 groups (healthy and LBP) for between subjects (4×2×2). MANOVA and multi-factor ANOVA tests were done. Linear parameters for center of pressure (COP) (deviation of amplitude, deviation of velocity, phase plane portrait (PPP), and overall mean velocity) and nonlinear parameters for COP and trunk angle ((recurrence quantification analysis) RQA and Lyapunov exponents) were chosen as dependent variables. Results indicated that NSLBP individuals relied more on ankle proprioception for postural stability. Similarly, RQA parameters for the COP on both sides and for the trunk sagittal angle indicated more repeated patterns of movement among the LBP cohort. Analysis of short and long Lyapunov exponents showed that people with LBP caused no use of all joints in their bodies (non-flexible), are less stable than healthy subjects.

The successful clinical application of patient-specific personalized medicine for the management of low back patients remains elusive. This study aimed to classify chronic nonspecific low back pain (NSLBP) patients using our previously developed and validated wearable inertial sensor (SHARIF-HMIS) for the assessment of trunk kinematic parameters. One hundred NSLBP patients consented to perform repetitive flexural movements in five different planes of motion (PLM): 0&deg, in the sagittal plane, as well as 15&deg, and 30&deg, lateral rotation to the right and left, respectively. They were divided into three subgroups based on the STarT Back Screening Tool. The sensor was placed on the trunk of each patient. An ANOVA mixed model was conducted on the maximum and average angular velocity, linear acceleration and maximum jerk, respectively. The effect of the three-way interaction of Subgroup by direction by PLM on the mean trunk acceleration was significant. Subgrouping by STarT had no main effect on the kinematic indices in the sagittal plane, although significant effects were observed in the asymmetric directions. A significant difference was also identified during pre-rotation in the transverse plane, where the velocity and acceleration decreased while the jerk increased with increasing asymmetry. The acceleration during trunk flexion was significantly higher than that during extension, in contrast to the velocity, which was higher in extension. A Linear Discriminant Analysis, utilized for classification purposes, demonstrated that 51% of the total performance classifying the three STarT subgroups (65% for high risk) occurred at a position of 15&deg, of rotation to the right during extension. Greater discrimination (67%) was obtained in the classification of the high risk vs. low-medium risk. This study provided a smart &ldquo, sensor-based&rdquo, practical methodology for quantitatively assessing and classifying NSLBP patients in clinical settings. The outcomes may also be utilized by leveraging cost-effective inertial sensors, already available in today&rsquo, s smartphones, as objective tools for various health applications towards personalized precision medicine.

Traumatic brain injury (TBI) has long been known as one of the most anonymous reasons for death around the world. This phenomenon has been under study for many years and yet it remains a question due to physiological, geometrical and computational complexity. Although the modeling facilities for soft tissue have improved, the precise CT-imaging of human head has revealed novel details of the brain, skull and meninges. In this study a 3D human head including the brain, skull, and meninges is modeled using CT-scan and MRI data of a 30-year old human. This model is named “Sharif University of Technology Head Trauma Model (SUTHTM)”. By validating SUTHTM, the model is then used to study the effect of +Gz acceleration on the human brain. Damage threshold based on loss of consciousness in terms of acceleration and time duration is developed using Maximum Brain Pressure criteria. Results revealed that the Max. Brain Pressure ≥3.1 are representation of loss of consciousness. 3D domains for the loss of consciousness are based on Max. Brain Pressure is developed.Copyright © 2016 by ASME

Responses of human body were studied in two adult age groups. The healthy subjects with no records of falling down or occupation in a crowded and noisy environment were elected. Mean age was 24 and 71 yrs. in young and elderly groups, respectively. Four experimental tasks were presented to subjects. Two involving flat standing with open and closed eyes and two were involving imposed disturbances. Two optoelectronic camera systems were used to measure body motion. The extents of postural sway were determined by processing the recorded data from force plate. The results were compared, and also provided the basis for kinematics analysis of body segments. For dynamic analysis, we used 3-link biomechanical model on a stationary triangular foot. Results from dynamic analysis indicated that, (a) The angular displacement of body segments was larger in elderly group, especially at the trunk; (b) The visual system had a dramatic effect on balance control, and its omission along with onset of senescence, has progressive effect, i.e. increased the amplitude and frequency of body sway, up to 2.4 and 1.5 times, respectively; (c) It has been proved that, in response to sudden stimulation, body employs certain strategy for muscle contraction. “Maximum torque, occurs in ankle, and respectively diminishes in joints, on its course toward upper segments”. The point is well consistent with the literature in this contest.

We proposed a model to investigate the transient diffusion of drug (sulphate) into the intervertebral disc. Using finite element method, drug diffusion was simulated and the concentration of diffused drug in each region of disc including Nucleus pulpous (NP), Inner annulus fibroses (IA), and Outer annulus fibroses (OA) was measured. In addition, to investigate the role of CEP permeability on the amount of diffused drug, model was simulated with different cartilage endplate (CEP) permeability. Having obtained concentration distribution for different cases, it was clearly shown that the amount of diffused drug is affected by the endplate permeability and the more permeable CEP, the more diffused drug into the disc specifically at the center of the disc. © 2011 IEEE.

In this paper, two lowest resonant frequencies and sensitivities of an AFM V-Shaped microcantilever made of functionally graded materials are studied. The beam is modeled by Euler-Bernoulli beam theory in which rotary inertia and shear deformation is neglected. It is assumed that the beam is made of a mixture of metal and ceramic with properties varying through the thickness of the beam. This variation is function of volume fraction of beam material constituents. The interaction between AFM tip and surface is modeled by two linear springs which expresses the normal and lateral contact stiffness. A relationship is developed to evaluate the sensitivity of FGM micro cantilever beam. Effect of volume fraction of materials and geometric parameters on resonant frequencies and sensitivities is studied. Results show that natural frequencies and sensitivities are significantly affected by volume fraction of material constituents and geometric parameters. Using these results, optimum geometric parameters and mass distributions of material constituents can be chosen so that high resolution images could be obtained.Copyright © 2010 by ASME

In this paper a lumped mass model was used to simulate the behavior of the human body during vertical vibration. Force method has been used to obtain the differential equations of the model, which were solved using simulink toolbox of Matlab software the appropriate damping and stiffness coefficients of shoes were chosen by comparing the results with the experimental data. The model has been used to produce a useful package, which has various abilities. We obtained the kinematics characteristics for each links of the model, in response of sine wave stimulation. This package has also the ability of comparing results by changing the damping and stiffness coefficients for the contact point (shoe) of the model. One of the important specifications of this package is its flexibility. With a little change in the codes of the program we can obtain the curves in response of other kinds of stimulations like noises and pulses.Copyright © 2002 by ASME

A new wearable assistive device (WAD) was developed to decrease required force on the lumbar spine in static holding tasks. In order to obtain moments on lumbar spine in two conditions, with and without WAD, a biomechanical static model was used for estimation of external moments on lumbar spine. The results of biomechanical models indicated that there was a reduction in the lumbar moment ranging from 20% to 43% using WAD depending on the load and flexion angle. A total of 15 male healthy subjects were tested to experimentally verify the predicted reduction of external moments on the spine by wearing WAD. Normalized electromyography (EMG) of the right and left lumbar and thoracic erector spinae (LES, TES), latissimus dorsi (LD), external oblique (EO), internal oblique (IO) and rectus abdominus (RA) muscles were monitored at three lumbar flexion positions (0°, 30° and 60°) in symmetric posture with three different loads (0, 5 and 15 kg) in two conditions of with and without WAD. The effects of WAD and load were significant for all muscles but the interaction effects were only significant for extensor muscles groups (p < 0.016). Results of statistical analysis (ANOVA) on the normalized EMG while wearing WAD indicated that the muscle activity of right and left LES, TES and LD muscles significantly decreased (p < 0.001). This reduction for right LES, TES, LD muscles at 15 kg load and 60° trunk flexion were 23.2%, 30% and 27.8%, respectively which were in good agreement with the biomechanical model results.