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    A computational dynamic finite element simulation of the thoracic vertebrae under blunt loading: spinal cord injury

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 41, Issue 2 , 2019 ; 16785878 (ISSN) Biglari, H ; Razaghi, R ; Ebrahimi, S ; Karimi, A ; Sharif University of Technology
    Springer Verlag  2019
    Spinal cord is a long, thin, tubular bundle of nervous tissue located in the vertebral column. Since the spinal cord is one of the most crucial pathways for information connecting of the central nervous system, it has to stay safe under any blunt impact loading, i.e., accident, punch, gunshot, burst, etc. Therefore, it is important to investigate the possible injuries that may occur in the vertebral column, especially the spinal cord, as a result of blunt loading. However, due to various experimental limitations, numerical modelling, specifically finite element (FE) models, has been beneficial in predicting the injury to the spinal cord. This study, thus, aimed at predicting the stresses and... 

    Obesity and obesity shape markedly influence spine biomechanics: a subject-specific risk assessment model

    , Article Annals of Biomedical Engineering ; Volume 45, Issue 10 , 2017 , Pages 2373-2382 ; 00906964 (ISSN) Ghezelbash, F ; Shirazi Adl, A ; Plamondon, A ; Arjmand, N ; Parnianpour, M ; Sharif University of Technology
    Underlying mechanisms of obesity-related back pain remain unexplored. Thus, we aim to determine the effect of obesity and its shapes on the spinal loads and the associated risks of injury. Obesity shapes were initially constructed by principal component analysis based on datasets on 5852 obese individuals. Spinal loads, cycles to vertebral failure and trunk stability margin were estimated in a subject-specific trunk model taking account of personalized musculature, passive ligamentous spine, obesity shapes, segmental weights, spine kinematics and bone mineral density. Three obesity shapes (mean and extreme abdominal circumferences) at three body weights (BWs) of 86, 98 and 109 kg were... 

    Parametric Finite Element Modeling of the Vertebral Trabecular Bone Behavior Based on Cellular Solids Theory

    , M.Sc. Thesis Sharif University of Technology Amjadi Kashani, Mohammad Reza (Author) ; Jalali, Mir Abbas (Supervisor) ; Parnianpour, Mohammad (Co-Advisor)
    Spine column is the most important musculoskeletal structures. One of the serious health problems in societies, especially among aged population is osteoporosis. Loss of bone density in bone structures is called osteoporosis which increases the risk of fracture due to a decrease of bone stiffness and bone strength. Spine is the most common sites for osteoporosis-related fractures. Current assessment of osteoporosis status is based on bone densitometry tools like QCT (Quantitative Computed Tomography) or DEXA (Dual Energy X-ray absorptiometry). With these methods it is only possible to estimate density without any consideration the morphology of trabecular making parts like rods and plates.... 

    Real-time Tracking of the Lumbar Spine with Surgical Navigation System and Biomechanical Modeling

    , M.Sc. Thesis Sharif University of Technology Sarrami, Saman (Author) ; Behzadipour, Saeed (Supervisor) ; Farahmand, Farzam (Co-Advisor)
    One of the most important parts of the human’s body is spine. Its anatomy is very complex and has many degrees off freedom. Many kinds of diseases might occur for this part. One of the ways of treatment for this part is surgery that it has different types. In the past decades the surgeries have been done very simple without the help of computers or robots. In other words the surgeon did the surgery with no use of lateral tools. For this reason the error in those surgeries was high. Doing a surgery on the spine level needs a special attention. As the technology improved very much in the last 2 decades the amount of errors has been reduced and various kinds of techniques came in the scene to... 

    Simulations of Dynamic Hand-Loading Activities by Using Musculoskeletal Modeling Based on Experimental Versus Full-Body Posture Prediction Neural Network Data

    , M.Sc. Thesis Sharif University of Technology Hosseini, Nesa (Author) ; Arjmand, Navid (Supervisor)
    Body posture is an essential input of musculoskeletal models that evaluate spinal loads in occupational activities. Posture is either measured in vivo via video-camera motion capture systems or predicted via artificial neural networks (ANNs) [1]. As video-camera measurements are impractical for use in real workstations, we have recently developed an ANN that predicts full-body posture during one- and two-handed static load-handling activities. This ANN, trained based on the posture data of 20 subjects each performing 204 static load-handling activities, uses 3D coordinates of the hand-load, body weight, and body height of the worker to predict 3D coordinates of 41 full-body skin markers. The... 

    Developmental barcoding of whole mouse via homing CRISPR

    , Article Science ; Volume 361, Issue 6405 , 2018 ; 00368075 (ISSN) Kalhor, R ; Kalhor, K ; Mejia, L ; Leeper, K ; Graveline, A ; Mali, P ; Church, G. M ; Sharif University of Technology

    Investigating the properties of optimal sensory and motor synergies in a nonlinear model of arm dynamics

    , Article Proceedings of the International Joint Conference on Neural Networks, 14 June 2009 through 19 June 2009, Atlanta, GA ; 2009 , Pages 272-279 ; 9781424435531 (ISBN) Bayati, H ; Vahdat, S ; Vosoughi Vahdat, B ; International Neural Network Society; IEEE Computational Intelligence Society ; Sharif University of Technology
    The vertebrate nervous system produces a wide range of movements flexibly and efficiently, in spite of high complexity and nonlinearity of their motor system. The existence of building blocks in motor system known as synergies can be a convincing solution to overcome the computational complexity. In mathematical perspective, optimal feedback control as a theory of motor coordination provides a coherent framework that leads to optimal synergies. Alternatively, some experiments in vertebrates have shown the involvement of spinal motor primitives in movement execution. The goal of this study is first extracting optimal synergies in nonlinear dynamics case and then investigating their biological... 

    Subject-specific 2D/3D image registration and kinematics-driven musculoskeletal model of the spine

    , Article Journal of Biomechanics ; Volume 57 , 2017 , Pages 18-26 ; 00219290 (ISSN) Eskandari, A. H ; Arjmand, N ; Shirazi Adl, A ; Farahmand, F ; Sharif University of Technology
    An essential input to the musculoskeletal (MS) trunk models that estimate muscle and spine forces is kinematics of the thorax, pelvis, and lumbar vertebrae. While thorax and pelvis kinematics are usually measured via skin motion capture devices (with inherent errors on the proper identification of the underlying bony landmarks and the relative skin-sensor-bone movements), those of the intervening lumbar vertebrae are commonly approximated at fixed proportions based on the thorax-pelvis kinematics. This study proposes an image-based kinematics measurement approach to drive subject-specific (musculature, geometry, mass, and center of masses) MS models. Kinematics of the thorax, pelvis, and...