Sharif Digital Repository

Low Back Pain (LBP) is an important public health problem and also a source of continuing economic concern in across the world. Many clinicians and researchers have focused on LBP due to the prevalence of it, especially in industrialized societies in recent years. Despite technological advances in diagnosis and the introduction of numerous interventions, besides increasing automation in the workplaces, the incidence of back pain in a wide range of workers in industrial environments has been reported. A better understanding of the different functions of the neuromuscular system of the spine may lead to adopt strategies to prevent LBP incidence as well as provide appropriate exercises... 

The effects of combined task demands on the way muscles are recruited to balance external loads during posture and movement is of great importance in quantitative analysis of upper arm function. Pain and disability of shoulder joint is becoming more important as population spends more often interacting with computers in seated position and carrying repetitive tasks using upper extremities. Shoulder joint that is more dependent on the muscles for its normal function than other joints such as hip due to its small articular surface and large range motion has been used here to study its coordination during isometric exertions. Since, the numbers of tasks that could be performed are enormous. In... 

In this study, by dividing spine motion in two part, ordinary movement and initial-final accelerated movement, the commands of CNS are evaluated by optimization methods to find synchronous and time varying synergies. Spine, which is a complex structure of vertebrae and cartilage, has been modeled by a 3D inverted pendulum with a ball and socket joint at L4/L5 incorporated with 18 muscle fascicles. Planning of point-to-point spine motion is performed by optimal control method in combined with cost function of kinematics and kinetic features that available in spine structure. In the second step, coactivation of muscles is predicted by utilizing static optimization along with stability... 

The existence of motor synergies in motor system as a tool for reducing degrees of freedom has been always debated. In the last two decades some experiments in vertebrates show the existence of motor primitives in spinal cord. In additional by recording electromyogram from frog some regular patterns have been shown. Recently, a motor coordination model based on stochastic optimal feedback control has extracted synergies by mathematical formulation. In addition, according to this model synergies are the optimal solution of the problem and not for simplifying it. However, this model is investigated in linear dynamics. In this thesis, first, an inverse method for extracting synergies is... 

Selection of muscle activation pattern to reach a specific goal by considering the complexities of neuromuscular system and the way it overcomes these complications, are of researchers’ space interest in motor control. One proposed solution for resolving these complexities is the concept of simple module (synergies) that suggests the combination of them leads to more complex activities. In the present work, the existence and arrangement of synergies in the lumbar spine have been studied. For this purpose, a model with 18- muscles at level of L4-L5 under utilized in the static condition. In order to obtain the muscular and stability synergies, a biomechanical model predicting muscle... 

Human walking as a rhythmic movement, despite of being simple in implementation, is so complex in biomechanical modeling and has attracted the attention of most of the researchers. Numerous theories and assumptions have been proposed for modeling this motor pattern. Central pattern generators are neural circuits in the spinal cord responsible for generating rhythmic motor patterns in rhythmic activities such as walking. On the other hand, muscle synergy has been introduced as a solution for alleviating the redundancy of the muscular system. In this hypothesis, the central nervous system activates muscle groups that are called muscle modules. Using this hypothesis facilitates the... 

Shoulder is one of the most important joints of the body with high degrees of freedom. Synergic analysis of the shoulder muscles shows the joint condition due to applied force or torque. The results of the linear COP parameters and nonlinear analysis indicate the characteristics of subjects postural stability. The flexi-bar is a rehabilitation tool which stimulates the muscles. In this study, the effect of bar on the body has been examined. The modeling is carried out in two horizontal and vertical condition of bar in sixteen separate positions in the upper right side quadrant of the model. Muscle activation and joint stiffness, force and torque were obtained. COP data in AP and ML were... 

Spinal cord injury (SCI) is one of the most important causes of disability in the youth and costs enormous expenses for the government. Most SCI subjects use wheelchair as their main way of locomotion while standing and walking can benefit them in various aspects. The role of lower extremity muscles has been investigated in paraplegic gait with active orthoses or in partial weight support condition. However, due to the large expenses of active orthoses, their application have been limited to clinical trials and yet most SCI individuals use traditional AFO and KAFO for walking. The role and significance of trunk and upper extremity muscles (TUEM) has been investigated only in balance... 

Human body movements are achieved by activating a number of muscles. It has been shown that the central nervous system (CNS) plays the main role in controlling rhythmic activities (including walking, chewing, etc.). However, the way the central nervous system works in controlling different parts of the body has always been discussed due to the excess degrees of freedom to perform certain tasks. Controlling a group of muscles (under the name of muscle synergy analysis) instead of each one of them has been one of the most attractive and efficient recent ideas to better understand the CNS function. Also, a similar concept can be expressed for kinematic synergies (by the degrees of freedom of... 

Injuries of neuro-musculoskeletal system impose large costs to the modem societies. Studying the strategies of CNS in planning and control of movements can be helpful in developing diagnoSiS, prognosis and treatment procedures in clinical view and also in designing rehabilitation system and humanoid robots. Tow important features of human movements are redundancy problem and structured variability. Previous studies solved the redundancy problem mainly with optimization methods. Also optimal feedback control theory is the only method that successfully modeled structured variability in voluntary movements. Despite the appropriate outputs this methods are not based on physiological facts... 

Integration of transportation demand management (TDM) policies, as a realistic and effective approach, is a challenging issue in urban policy studies. This study examines the role of transportation demand management (TDM) policy packages on commuters' mode choice in the city of Tehran. The analysis is based on the results of stated preferences survey developed by efficient choice design as a specialized type of fractional factorial design approach. Five policies, namely increasing parking cost, increasing fuel cost, cordon pricing, transit time reduction and transit access improvement, are assessed in considering six modes of travel to work place. A multinomial logit model has been developed... 

Our body makes use of many degrees of freedom in muscle space. As a result, there are many solutions for activating muscles when performing a specific task. “how our central nervous system (CNS) controls abundant degrees of freedom?” has been a popular question for researchers in the field of motor control since Bernstein. The existence of muscle synergies is one of the proposed hypothesis, and there is experimental evidence that they are encoded in our CNS as building blocks. The aim of this study is to study the effect of training on the number, structures, and activation profiles of muscle synergies that are used for maintaining balance. For this purpose, electromyography data from 28... 

The problem of degrees of freedom states that there are several ways to take advantage of the multiple joints of the body to perform a motor skill. This issue was first raised by Nikolai Bernstein. In previous studies on the Bernstein hypothesis, movement coordination has often been evaluated by calculating variance changes in joint movements and using statistical indicators, and synergy analysis has not been used.In this study, the effect of exercise on balance skills in healthy individuals was investigated using synergy analysis. For this purpose, movement data of 8 healthy individuals were recorded in two sessions before and after exercise while maintaining their balance on the balance... 

Despite significant progress in cancer treatment, drug resistance remains a major challenge. Synergistic drug combinations offer a promising approach to overcome drug resistance and reduce side effects. Still, despite high-throughput testing technologies, existing drug combination databases suffer from biases and a lack of diversity in tested cancer cell lines, which challenges the prediction of drug response on novel cell targets. To address this critical need, we designed a two-level deep learning method that uses large-scale gene expression datasets to estimate the score and synergy of drug compounds on a wide variety of cancer cell lines. Our model includes an auto-encoder that train on... 

Cerebral palsy (CP) is one of the most common motor disability among children that caused by damage to brain or defective development of brain before, during or just after birth. Due to this damage, children with CP have cognitive and motor problems. As an important activity of daily living, walking enhances independence, social activities and quality of life. Much of therapy for children is aimed to improve their gait. A usual technique to evaluate how a person walk and detect abnormal features in walking pattern is gait analysis. Lots of studies have been done on gait kinematics of CPs and classified them based on their kinematis. The purpose of this thesis is studying muscles activity of...