Search for: physiological-models
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    Modeling of Human Decision Making in Problem Solving Based on Physiological Models of Neuron

    , M.Sc. Thesis Sharif University of Technology Shirzadeh, Hossein (Author) ; Vosughi Vahdat, Bijan (Supervisor)
    How the human nervous system works is one of the most important topics in science and in this topic providing a model of it is scientists' main concern. The human brain that has been formed from a large number of nerve cells lets it do complex computations. The structure of cognition, memorizing and processing which are some of human features are being studied in many fields of science named "brain and cognitive science".
    In this study, we will point to modeling of one of the human cognitive phenomena (decision making in problem solving). In this modeling, we aim to connect the microscopic and macroscopic levels of the nervous system to each other.
    First, we will give an introduction... 

    Modeling the Relationship between Central Aortic Pressure and Radial Photoplethysmogram in Flow-mediated Dilation Test

    , Ph.D. Dissertation Sharif University of Technology Parsafar, Mohammad Habib (Author) ; Vosughi Vahdat, Bijan (Supervisor) ; Zahedi, Edmond (Supervisor)
    According to the World Health Organization, about 35% of deaths worldwide are due to cardiovascular diseases, therefore the evaluation of vascular endothelial function has great prognostic and diagnostic value for cardiovascular diseases. The conventional noninvasive method for endothelial function evaluation is the measurement of flow-mediated dilation in brachial artery using ultrasound imaging (FMD-US). As the accuracy of FMD-US depends on the operator's skill and the resolution of the ultrasound images, this method has not been adopted. In this work, we propose to use a low cost, easily-accessible surrogate signal, the photoplethysmogram (PPG) to implement the FMD test. Whereas previous... 

    Variations in trunk muscle activities and spinal loads following posterior lumbar surgery: A combined in vivo and modeling investigation

    , Article Clinical Biomechanics ; Volume 30, Issue 10 , 2015 , Pages 1036-1042 ; 02680033 (ISSN) Jamshidnejad, S ; Arjmand, N ; Sharif University of Technology
    Background Iatrogenic injuries to paraspinal muscles during posterior lumbar surgery cause a reduction in their contractile cross-sectional area and thus presumably their postoperative activation. This study investigates the effect of such intraoperative injuries on postoperative patterns of muscle activations and spinal loads during various activities using a combined modeling and in vivo MR imaging approach. Methods A three-dimensional, multi-joint, musculoskeletal model was used to estimate pre- and postoperative muscle forces and spinal loads under various activities in upright and flexed postures. According to our in vivo pre- and postoperative (∼ 6 months) measurements in six patients... 

    Uncontrolled manifold analysis of gait kinematic synergy during normal and narrow path walking in individuals with knee osteoarthritis compared to asymptomatic individuals

    , Article Journal of Biomechanics ; Volume 141 , 2022 ; 00219290 (ISSN) Shafizadegan, Z ; Sarrafzadeh, J ; Farahmand, F ; Salehi, R ; Rasouli, O ; Sharif University of Technology
    Elsevier Ltd  2022
    Knee osteoarthritis (KOA) is a common musculoskeletal disorder resulting in altered gait patterns. Uncontrolled manifold (UCM) analysis has been demonstrated as a useful approach for quantitative analysis of motor variability and synergies. The present study aimed to investigate the changes in the kinematic synergy, controlling the center of mass (COM) position while walking on normal and narrow paths in people with KOA compared to asymptomatic participants. In this cross-sectional study, twenty people with mild to moderate KOA and twenty asymptomatic individuals walked at their comfortable preferred speed across normal and narrow paths on a treadmill. The UCM analysis was performed... 

    Tracking the 3D configuration of human joint using an MR image registration technique

    , Article ASME 2010 5th Frontiers in Biomedical Devices Conference and Exhibition, BIOMED 2010, 20 September 2010 through 21 September 2010 ; 2010 , Pages 93-94 ; 9780791849453 (ISBN) Mostafavi Yazdi, S. K ; Farahmand, F ; Jafari, A ; Sharif University of Technology
    Surface registration is a necessary step and widely used in medical image-aided surgery. It's relevance to medical imaging is that there is much useful anatomical information in the form of collected surface points which originate from complimentary modalities. In this study, the kinematic relations between two point clouds with different coordinate definitions have been generated. Using Influence Method of surface modeling for extracting point clouds functions, the transformation matrix would be resulted. The proposed method was applied for an experimental femur data points(651 points) using the MRI images. These data points were transformed in a 30 degrees flexion of knee. This... 

    Sex-Dependent estimation of spinal loads during static manual material handling activities—combined in vivo and in silico analyses

    , Article Frontiers in Bioengineering and Biotechnology ; Volume 9 , 2021 ; 22964185 (ISSN) Firouzabadi, A ; Arjmand, N ; Pan, F ; Zander, T ; Schmidt, H ; Sharif University of Technology
    Frontiers Media S.A  2021
    Manual material handling (MMH) is considered as one of the main contributors to low back pain. While males traditionally perform MMH tasks, recently the number of females who undertake these physically-demanding activities is also increasing. To evaluate the risk of mechanical injuries, the majority of previous studies have estimated spinal forces using different modeling approaches that mostly focus on male individuals. Notable sex-dependent differences have, however, been reported in torso muscle strength and anatomy, segmental mass distribution, as well as lifting strategy during MMH. Therefore, this study aimed to use sex-specific models to estimate lumbar spinal and muscle forces during... 

    Robust control of LVAD based on the sub-regional modeling of the heart

    , Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2934-2943 ; 10263098 (ISSN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Sharif University of Technology  2016
    Left Ventricular Assist Devices (LVAD) have received renewed interest as a bridge-to-transplantation as well as a bridge-to-recovery device. Ironically, reports of malfunction and complications have hindered the growth of this device. In particular, the main concern is LVAD's susceptibility to excessive backlash and suction as a result of ows that are either too low or high, respectively. This study utilizes a well-established physiological model of the cardiovascular system as a reliable platform to study a proposed adaptive robust controller for a rotary motor based LVAD which overcomes such shortcomings. Proposed controller performance is evaluated by comparing simulated natural heart... 

    Prosthetic knee using of hybrid concept of magnetorheological brake with a T-shaped drum

    , Article 2015 IEEE International Conference on Mechatronics and Automation, ICMA 2015, 2 August 2015 through 5 August 2015 ; Aug , 2015 , Pages 721-726 ; 9781479970964 (ISBN) Sayyaadi, H ; Zareh, S. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    This paper focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. Knee uses magnetic fields to vary the viscosity of the MR fluid, and thereby its flexion resistance. Exerted transmissibility torque of the knee greatly depends on the magnetic field intensity in the MR fluid. In this study a rotary damper using MR fluid is addressed in which a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main objective of this study is to investigate a prosthetic knee with one activating rotary disc to accomplish necessary braking torque in walking gait via implementing of Newton's equation of... 

    Probe into the molecular mechanism of ibuprofen interaction with warfarin bound to human serum albumin in comparison to ascorbic and salicylic acids: Allosteric inhibition of anticoagulant release

    , Article Journal of Chemical Information and Modeling ; Volume 61, Issue 8 , 2021 , Pages 4045-4057 ; 15499596 (ISSN) Kalhor, H. R ; Taghikhani, E ; Sharif University of Technology
    American Chemical Society  2021
    The release of anticoagulant drugs such as warfarin from human serum albumin (HSA) has been important not only mechanistically but also clinically for patients who take multiple drugs simultaneously. In this study, the role of some commonly used drugs, including s-ibuprofen, ascorbic acid, and salicylic acid, was investigated in the release of warfarin bound to HSA in silico. The effects of the aforementioned drugs on the HSA-warfarin complex were investigated with molecular dynamics (MD) simulations using two approaches; in the first perspective, molecular docking was used to model the interaction of each drug with the HSA-warfarin complex, and in the second approach, drugs were positioned... 

    Physiological and psychological neural system modeling for a key-pressing test

    , Article Proceedings of the IASTED International Conference on Biomedical Engineering, Salzburg, 25 June 2003 through 27 June 2003 ; 2003 , Pages 66-70 ; 0889863539 (ISBN) Mahmudi, H ; Shahdi, S. A ; Vahdat, B. V ; IASTED ; Sharif University of Technology
    The model introduced in this article for neural system describes both physiological and psychological concepts of neural system and is based on the models of individual elements of the system. This model includes psychological characteristics such as; perception, prediction, learning and response planning, and physiological features such as; sensory analysis, memory and motor execution. The model is designed in such a way that it describes the performance of the neural system for a key-pressing test. The key-pressing experiment consists of a screen with numbers from 1 to 9, which is shown to the operator where one of the numbers is specified by a special color and the operator is to push the... 

    Parameter estimation of a mathematical model describing the cardiovascular-respiratory interaction

    , Article Computing in Cardiology, 6 September 2015 through 9 September 2015 ; Volume 42 , 2015 , Pages 617-620 ; 23258861 (ISSN) ; 9781509006854 (ISBN) Goldoozian, L. S ; Hidalgo Muñoz, A. R ; Zarzoso, V ; Zahedi, E ; Murray A ; Sharif University of Technology
    IEEE Computer Society  2015
    Short-term interaction between heart rate (HR) and physiological measures like blood pressure and respiration reveals relevant information about autonomic nervous system (ANS) function. Complex mathematical models for describing their couplings have been proposed in the literature. However, an accurate estimation of their parameters in an inverse modeling problem is crucial to extract reliable ANS related indices. This study considers a physiologically-based model of the cardiovascular-respiratory system and ANS control that presents the neural and mechanical effects of respiration separately. The estimation method is evaluated on synthetic signals. An accurate estimation of the... 

    Multidimensional modeling of the stenosed carotid artery: A novel CAD approach accompanied by an extensive lumped model

    , Article Acta Mechanica Sinica/Lixue Xuebao ; Vol. 30, issue. 2 , 2014 , p. 259-273 Kashefi, A ; Mahdinia, M ; Firoozabadi, B ; Amirkhosravi, M ; Ahmadi, G ; Saidi, M. S ; Sharif University of Technology
    This study describes a multidimensional 3D/lumped parameter (LP) model which contains appropriate inflow/outflow boundary conditions in order to model the entire human arterial trees. A new extensive LP model of the entire arterial network (48 arteries) was developed including the effect of vessel diameter tapering and the parameterization of resistance, conductor and inductor variables. A computer aided-design (CAD) algorithm was proposed to efficiently handle the coupling of two or more 3D models with the LP model, and substantially lessen the coupling processing time. Realistic boundary conditions and Navier-Stokes equations in healthy and stenosed models of carotid artery bifurcation... 

    Modelling and analysis of the effect of angular velocity and acceleration on brain strain field in traumatic brain injury

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 3 A , 2013 ; 9780791856215 (ISBN) Hoursan, H ; Ahmadian, M. T ; Barari, A ; Beidokhti, H. N ; Sharif University of Technology
    Traumatic brain injury (TBI) has long been known as one of the most anonymous reasons for death around the world. A presentation of a model of what happens in the process has been under study for many years; and yet it remains a question due to physiological, geometrical and computational complications. Although the facilities for soft tissue modeling have improved and the precise CT-imaging of human head has revealed novel details of brain, skull and the interface (the meninges), a comprehensive FEM model of TBI is still being studied. This study aims to present an optimized model of human head including the brain, skull, and the meninges after a comprehensive study of the previous models.... 

    Model-based fiducial points extraction for baseline wandered electrocardiograms

    , Article IEEE Transactions on Biomedical Engineering ; Volume 55, Issue 1 , 2008 , Pages 347-351 ; 00189294 (ISSN) Sayadi, O ; Shamsollahi, M. B ; Sharif University of Technology
    A fast algorithm based on the nonlinear dynamical model for the electrocardiogram (ECG) is presented for the precise extraction of the characteristic points of these signals with baseline drift. Using the adaptive bionic wavelet transform, the baseline wander is removed efficiently. In fact by the means of the bionic wavelet transform, the resolution in the time-frequency domain can be adaptively adjusted not only by the signal frequency but also by the signal instantaneous amplitude and its first-order differential, which results in a better baseline wander cancellation. At the next step the parameters of the model are chosen to have the least square error with the original ECG. Determining... 

    Investigation of the different parameters contributing to bubble sticking inside physiological bifurcations

    , Article Medical and Biological Engineering and Computing ; Volume 60, Issue 2 , 2022 , Pages 599-618 ; 01400118 (ISSN) Salajeghe, R ; Saidi, M. S ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Gas embolotherapy (GE) is a developing medical method which can be utilized either as an autonomous therapeutic method to treat vascularized solid tumors, or it can be combined with other medical procedures—such as high-intensity focused ultrasound—to improve their efficiency. This paper is dedicated to investigating the different parameters which influence bubble lodging inside human vasculature via 2D-modeling of bubble dynamics in arteries’ and arterioles’ bifurcations which are potential sticking positions. Values used in the simulations are in accordance with the non-dimensional physiological numbers. It is found out that inlet pressure plays a decisive role in bubble lodging; the lower... 

    Introducing a distributed model of the heart

    , Article Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, 24 June 2012 through 27 June 2012 ; June , 2012 , Pages 419-424 ; 21551774 (ISSN) ; 9781457711992 (ISBN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Conventional models of cardiovascular system (CV) frequently lack required detail. Once utilized to study the heart function, these models focus primarily on the overall relationship between pressure, flow and volume. This study proposes a localized and regional model of the CV system. It utilizes non-invasive blood flow and pressure seed data and temporal cardiac muscle regional activation to predict the operation of the heart. Proposed localized analysis considers specific regions of the heart, namely base, mid and apex sections of the left ventricle. This modular system is based on a hydraulic electric analogy model, estimating desired parameters, namely resistance (R), compliance (C),... 

    Improved artificial neural networks for 3D body posture and lumbosacral moment predictions during manual material handling activities

    , Article Journal of Biomechanics ; Volume 131 , 2022 ; 00219290 (ISSN) Mohseni, M ; Aghazadeh, F ; Arjmand, N ; Sharif University of Technology
    Elsevier Ltd  2022
    Body posture measurement approaches, required in biomechanical models to assess risk of musculoskeletal injuries, are usually costly and/or impractical for use in real workplaces. Therefore, we recently developed three artificial neural networks (ANNs), based on measured posture data on several individuals, to predict whole body 3D posture (coordinates of 15 markers located on body's main joints), segmental orientations (Euler angles of 14 body segments), and lumbosacral (L5-S1) moments during static manual material handling (MMH) activities (ANNPosture, ANNAngle, and ANNMoment, respectively). These ANNs require worker's body height, body weight (only for ANNMoment), hand-load 3D position,... 

    Hyperthermia-induced protein corona improves the therapeutic effects of zinc ferrite spinel-graphene sheets against cancer

    , Article RSC Advances ; Vol. 4, issue. 107 , 2014 , p. 62557-62565 Hajipour, M. J ; Akhavan, O ; Meidanchi, A ; Laurent, S ; Mahmoudi, M ; Sharif University of Technology
    Superparamagnetic zinc ferrite spinel-graphene nanostructures were synthesized as potential therapeutic agents in the magnetic targeted photothermal therapy of cancer and/or drug delivery. The global temperature of the solution and the local temperature at the nanoparticle (NP) surface determine the protein corona composition/content, which in turn affects the biological effects of NPs and the corresponding physiological responses. Therefore, it is rational to hypothesize that spinel-graphene nanostructures may have distinct protein corona compositions and contents, and therapeutic and toxic effects under laser irradiation. To assess this hypothesis, the effects of laser irradiation on the... 

    Gut-on-a-chip: Current progress and future opportunities

    , Article Biomaterials ; Volume 255 , 2020 Ashammakhi, N ; Nasiri, R ; Barros, N. R. D ; Tebon, P ; Thakor, J ; Goudie, M ; Shamloo, A ; Martin, M. G ; Khademhosseni, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Organ-on-a-chip technology tries to mimic the complexity of native tissues in vitro. Important progress has recently been made in using this technology to study the gut with and without microbiota. These in vitro models can serve as an alternative to animal models for studying physiology, pathology, and pharmacology. While these models have greater physiological relevance than two-dimensional (2D) cell systems in vitro, endocrine and immunological functions in gut-on-a-chip models are still poorly represented. Furthermore, the construction of complex models, in which different cell types and structures interact, remains a challenge. Generally, gut-on-a-chip models have the potential to... 

    Evaluation of endothelial response to reactive hyperaemia in peripheral arteries using a physiological model

    , Article International Journal of Biomedical Engineering and Technology ; Volume 33, Issue 4 , 2020 , Pages 305-324 Parsafar, M. H ; Zahedi, E ; Vahdat, B. V ; Sharif University of Technology
    Inderscience Publishers  2020
    Non-invasive measurement of flow-mediated dilation (FMD) in the brachial artery for assessing endothelial function is costly and operator-dependent, limiting its application to research cases. In this paper, an approach based on a physiological model between normalized central blood pressure and finger photoplethysmogram is presented. Baseline model parameters are estimated using a genetic algorithm in 30 subjects consisting of ten normal blood pressure (BP), ten high-BP and ten elderly volunteers. Beat-to-beat fitness values after reactive hyperaemia are calculated using baseline (before cuff occlusion) data. Results show that stimulus-induced changes are fairly described with a first order...