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Biomedical Engineering (ICBME), 2013 20th Iranian Conference on

Date 18-20 Dec. 2013

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  • Predicting emotions induced by music using system identification theory

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB) |  | HTML iconHTML  

    Modeling the emotional content of music is of great importance, since it is believed that music is capable of inducing different emotions. In this study we present an Autoregressive with Exogenous Input (ARX) model based on system identification theory for modeling the emotional content of music in a two dimensional emotion space and also a nonlinear Autoregressive with Exogenous Input (NARX) model to capture the nonlinear characteristics of the system. We also investigate the causal relationship between musical features and the induced emotions by removing the autoregressive terms from the developed model. Finally A brief discussion about the most important features is presented. View full abstract»

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  • Mechanical design, simulation and nonlinear control of a new exoskeleton robot for use in upper-limb rehabilitation after stroke

    Page(s): 5 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (349 KB) |  | HTML iconHTML  

    Cerebrovascular accident (CVA) or stroke is one of the main causes of disability. It affects millions of people worldwide. One symptom of stroke is disabled arm function. Restoration of arm function is necessary to resuming activities of daily living (ADL). Along with traditional rehabilitation techniques, robot-aided therapy has emerged in recent years. Robot-aided arm therapy is more intensive, of longer duration and more repetitive. By using robots repetitive dull exercises can turn into a more challenging and motivating tasks such as games. Besides, robots can provide a quantitative measure of the rehabilitation progress. This paper introduces a new robot for shoulder rehabilitation. The shoulder rehabilitation system (S.R.S) has three degrees of freedom (DOFs) for three rotational degrees of freedom of the shoulder. It also allows the additional translational DOFs of the shoulder to avoid discomfort to the patient. A new open circular mechanism is proposed for the third joint. The mechanical structure is designed and optimized in Solidworks and it is based on the properties of upper limb of an adult person. The proposed control algorithm is inverse dynamics control which is intended to be used in passive rehabilitation. The proposed control can efficiently track the desired trajectory and reject constant bounded disturbance input to the system. View full abstract»

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  • A PCA-assisted EMG-driven model to predict upper extremities' joint torque in dynamic movements

    Page(s): 11 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (391 KB) |  | HTML iconHTML  

    To relate electromyographic signals (EMG) to net joint torque, different approaches have been taken into account. In this regard, some researchers chose to use Principal Component Analysis (PCA). A Study in 2001 reported a linear relationship between the PCA-processed EMG data and the joint torque while investigating isometric movements. In this project we questioned the possibility to use this method for free dynamic tasks. Four healthy subjects participated in the current study, performing three sets of Dumbbell Kick Back exercise for five different dumbbell weights. The net joint torque was calculated using the kinematic data in an inverse dynamics model. Meanwhile the EMG data were processed with a PCA method, and then were input to the model to estimate the joint torque. In order to predict this torque, we used two models; a single-input model that was fed with the PCA-processed EMG of the all corresponding muscles; and a double-input model that utilized the PCA-processed EMG data of the agonist and antagonist muscles separately. The results demonstrated that both the single-input and double-input models are capable of predicting the torque for both isometric and free dynamic tasks. Employing a paired t-test we found that the double-input model was significantly more successful in estimating the torque comparing to the single-input model (p <; 0.005). The other factor (the movement type) proved to also have a significant effect on the estimation outcome (p <; 0.0005). In general, this study suggests that a linear relationship exists between PCA-processed EMG data and the joint torque in both isometric and free dynamic movements; however, in order to have a better estimate of the net joint torque, distinguishing the agonist-antagonist muscle groups' generated torques may be beneficial. View full abstract»

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  • The appropriate dimensions of the porous micro-channel for blood ions separation

    Page(s): 17 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (797 KB) |  | HTML iconHTML  

    Separation of nano-particles from the fluid in micro-channels has a wide application in industry and is the subject of a plenty of researches today. In the present paper, the flow of blood plasma which contains ions and is considered as nano-particles in a micro-channel has been studied. The channel inside wall is of a porous material which consists of amino functionalized group-type one that causes the ions to separate from the blood and absorb to the channel wall because of electrostatic interaction between blood ions and micro-channel wall material. Based on this study at first time, an optimum dimensions have been represented to decrease the process time and channel length. View full abstract»

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  • Blood flow simulation in a stenotic vessel surrounded by biological tissue

    Page(s): 22 - 26
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1083 KB) |  | HTML iconHTML  

    An abnormal narrowing of a blood vessel (stenosis) is investigated in this study. The present work provides a simulation of blood in a vessel with 50% stenosis. In addition, the effects of tissue surrounding the blood vessel on displacements and stresses in stenotic vessel wall are considered. The analysis consists of two distinct but coupled procedures: first, a fluid-dynamics analysis including a calculation of the velocity field and pressure distribution in the blood (variable in time and in space); second, a mechanical analysis of the deformation of the tissue and vessel. To do so, COMSOL Multiphysics as a powerful software was used to simulate the wall-blood interaction. The diameter of vessel is 8 millimeters and the blood assumed to be a Newtonian and incompressible fluid. In addition to, the walls of vessel and surrounding biological tissue were assumed to be a hyper-elastic material. The results indicated that the stresses and displacement of blood vessel are completely affected by surrounding tissue. In the other hand for studying blood flow in the vessel we cannot ignore the effects of surrounding tissue and flexibility of the vessel walls. Furthermore velocity and shear rate of blood flow were also investigated. View full abstract»

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  • Individual teeth segmentation in CBCT and MSCT dental images using watershed

    Page(s): 27 - 30
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (361 KB) |  | HTML iconHTML  

    Teeth segmentation is an important step in human identification and Content Based Image Retrieval (CBIR) systems. This paper proposes a new approach for teeth segmentation using morphological operations and watershed algorithm. In Cone Beam Computer Tomography (CBCT) and Multi Slice Computer Tomography (MSCT) each tooth is an elliptic shape region that cannot be separated only by considering their pixels' intensity values. For segmenting a tooth from the image, some enhancement is necessary. We use morphological operators such as image filling and image opening to enhance the image. In the proposed algorithm, a Maximum Intensity Projection (MIP) mask is used to separate teeth regions from black and bony areas. Then each tooth is separated using the watershed algorithm. Anatomical constraints are used to overcome the over segmentation problem in watershed method. The results show a high accuracy for the proposed algorithm in segmenting teeth. Proposed method decreases time consuming by considering only one image of CBCT and MSCT for segmenting teeth instead of using all slices. View full abstract»

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  • The representation of fuzzy model for auditory brainstem response to one syllable speech stimuli /da/

    Page(s): 31 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (691 KB) |  | HTML iconHTML  

    In this paper a nonlinear fuzzy model was introduced to reveal the dynamics of auditory brainstem response to one syllable speech stimuli /da/, in normal Persian speaking subjects. This model represents the input-output behavior of the brainstem in generating cABR (complex auditory brainstem response) to consonant-vowel /da/. Fuzzy models have been successfully applied to the identification of complex nonlinear dynamical systems such as biological process due to their ability to overcome the vagueness and uncertainty of these systems. The ability of model in predicting cABR signals using fuzzy rules that describing the dynamics of cABRs to /da/ was validated. The total error achieved by cross-validation of model is 0.1329 with variance of 9.02×10-4. Identification of the nonlinear behavior of auditory system can help to understand the brainstem function in encoding acoustic cues in normal subjects. View full abstract»

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  • Impairment of Long-Term Potentiation in Alzheimer's Disease: A computational study based on tripartite synapse structure

    Page(s): 37 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (918 KB) |  | HTML iconHTML  

    In this work we propose a model to describe impairment of Long-Term Potentiation (LTP) due to Amyloid Beta (Aβ) accumulation during Alzheimer's Disease (AD) in hippocampus. The model embeds astrocyte-neuron interactions and Spike Timing-Dependent Plasticity (STDP) in CA3-CA1 synapses. In our proposed model, considering physiological facts, each astrocyte has a bidirectional signaling with four neurons, consisting of two pre-synaptic and two post-synaptic neurons. Sustained elevation in strength of each synapse leads to an increase in strength of other adjacent synapse, and finally to coupling between those synapses; this is known as LTP. We increased probability of pre-synaptic glutamate release to the level of reported experimental data on AD. As expected, increase of pre-synaptic glutamate release elevates astrocytic calcium. Due to excessive elevation of astrocytic calcium loss of calcium homeostatic, depression in synaptic strength, disruption of slow inward NMDA currents and finally impairment of LTP occur. Our results confirm the hypothesis that although calcium endocytosis is vital to induce LTP, fast and excessive increase of astrocytic calcium makes major problems and impairments for the LTP. View full abstract»

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  • A fully automated segmentation of radius bone based on active contour in wrist MRI data set

    Page(s): 42 - 47
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1161 KB) |  | HTML iconHTML  

    Advanced medical imaging techniques require high performance segmentation algorithms. Extracting the structures of interest accurately is one of the main challenges in medical imaging segmentation. In this paper a methodological approach based on active contour is proposed for fully automated segmentation of radius bone. As soft tissues like tendons, muscles and fat around the bone have close intensities to internal parts of the bone, accurate segmentation is difficult. Here the designed framework takes an MR image including radius bone as input and produces the segmented radius bone in 3D voxel set. The multi-step approach for segmentation is as following. Since our data set was much noisier, at first we denoised and enhanced contrast of the data using wavelet transform. Then an initial segmentation was produced focusing on edge map. Next, according to anatomical knowledge about the radius bone shape and size in intermediate slices, radius bone was extracted in this slice and used as the mask slice for adjacent slices. This masking procedure was applied to all slices with a 3D approach. After that we derived a convex hull region around the radius bone. This step was done for whole slices as regions of interest. Finally the estimated convex region is used as an initial mask for active contour. This framework was tested on more than 600 coronal MR slices of 23 subjects. In comparison to manual segmentation our method showed an average Dice similarity coefficient DSC and kappa statistics of 94.82% and 92.46% respectively. In the future works we utilize the proposed approach as part of a computer-aided diagnosis system for bone age estimation. View full abstract»

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  • Modeling blood flow & pressure in systemic circulation with cuff occlusion

    Page(s): 48 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (879 KB) |  | HTML iconHTML  

    Flow Mediated Dilation (FMD) is a non-invasive method to assess vascular health. In this method cuff occlusion is used to create reactive hyperemia and measure the following dilation of brachial artery. Although many researches have been conducted in this area, there still exist many debates about the method as the position of the cuff, duration of the occlusion and the involved physiological procedures. This study is trying to provide a platform by using a model to analyze these procedures. In this regard an electrical model for circulation is implemented consisting of 63 segments for large and 30 for peripheral arteries. The resulted pressure and flow signals are presented which are close to what is expected according to the literature. Cuff occlusion is also added to this model as a variable resistor and the results are depicted and compared with real measurements. The provided platform will further be used to add the model of involved physiological mechanisms and regulations. View full abstract»

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  • Mathematical modeling of heart rate and blood pressure variations due to changes in breathing pattern

    Page(s): 54 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1148 KB) |  | HTML iconHTML  

    Analysis of the heart rate (HR) variation due to respiration, known as respiratory sinus arrhythmia (RSA), is a method to assess the autonomic nervous system (ANS) function. In this paper a physiologically-based mathematical model consisting of the cardiorespiratory system and ANS control has been used in order to study the cardiovascular response (mean arterial blood pressure and HR) to breathing with different respiration rates and tidal volumes. Simulation results show that RSA has its maximal amplitude at the respiration frequency of 0.12 Hz and that RSA amplitude varies linearly by tidal volume. These results are in agreement with real data from the literature. In addition, the amplitude of the variations of the simulated blood pressure (BP) in each respiratory cycle is maximum at almost the same respiratory rate as RSA. View full abstract»

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  • Investigating the role of foot placement on the muscular forces of knee extensors in horizontal leg press: A static optimization approach

    Page(s): 59 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (735 KB) |  | HTML iconHTML  

    Horizontal leg press is a basic weight training exercise to strengthen extensor muscles of knee joint. Considering the specific purpose of this training, it's performed with different techniques. One of the major debates about performing this task concerns foot placement on the foot-plate. In this study, in order to investigate the effect of foot placement on the muscle contraction of knee extensors, a 3-DOF musculoskeletal model of lower-extremity was developed. This model was comprised of 40 skeletal muscles of lower-extremity. Each muscle was modeled with a phenomenological Hill-based model in accompanied with a rigid tendon. Considering the position of feet on the foot-plate (high or low), two types of experiments were designed: Leg Press High (LPH) and Leg Press Low (LPL). 6 healthy volunteers (2 women and 4 men) participated in this study. Experiments were performed at 30% and 70% of each person's MVC (the maximum weight in which a person could perform the exercise correctly) on the LPL and LPH protocols. Amalgamating the mean values of kinematic data and a constrained static optimization (sum of squared activations as the objective function and discritisized state equations of the multibody system as constraints), the required activation level of each muscle was obtained. The results showed a significant difference between the obtained muscle forces for knee extensors (vastus intermedius, vastus lateralis, vastus medialis, and rectus femoris) in each technique (p<;0.05). The muscle forces obtained in LPH technique were significantly smaller from the same ones in LPL. This observation suggests that if strengthening the knee extensors is of desire, LPH technique is not the correct format for performing the exercise. Another important spotlight in the results concerned the activation patterns of knee extensors. Despite the synergic behavior of all the extensors, because of the different operating range of these muscles, dissimilarity between activation pa- terns was observed. View full abstract»

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  • Analyzing synergistic and antagonistic muscle behavior during elbow planar flexion-extension: Entropy-assisted vs. shift-parameter criterion

    Page(s): 65 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4722 KB) |  | HTML iconHTML  

    Providing a capable musculoskeletal model for predicting antagonistic muscle forces has been dramatically flourished in recent decades. To reach this destiny, many researchers have struggled to modify objective functions in optimization-based models. The purpose of this paper is to compare two objective functions (Entropy-assisted and shift parameter objective function) exhibited in the literature for predicting muscle co-contraction. Furthermore, the effect of these objective functions in forecasting synergic muscles pattern was taken into account. To do so, a 2 DOF upper limb skeletal model actuated with 15 muscles, has been developed. A phenomenological Hill-based model in accompanied with a rigid tendon was employed to represent musculotendon units. While performing a flexion/extension in the elbow, the upper arm was held stationary in a vertical pose. Exploiting the kinematic data and considering different values (range 0 to 1 with step of 0.1) for entropy weight and shift parameter in the objective function of the static optimization problems, activation level of muscles spanning the elbow was obtained. The results showed that by increasing either of these parameters activation level of agonist and antagonist muscles rise. Besides, inspecting the results, it was clear that both of the optimization problems led to a same trend in the results and by choosing proper weight and shift parameter it was possible to minimize the difference between the obtained results from these two objective functions. Furthermore, considering a graphical approach it was showed that the entropy-assisted problem was a convex one which tried to obtain a minimum state of total activation. Contemplating this fact and utilizing each muscle's moment generation capacity, synergic behavior of muscles spanning elbow was discussed. We also examined the validity of the results, using EMG signals of Brachioradialis (BRD) and lateral head of Triceps (TRILAT). Although EMG signal of BRD was some- ow consistent with activation level of this muscle, EMG signal of TRILAT was in conflict with the results of static optimization problem. View full abstract»

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  • Quantifying variability of young and older adults during gait with linear and nonlinear tools

    Page(s): 71 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    Variability of the S1 displacement in frontal plane during gait was quantified with nonlinear and traditional linear tools including Largest Lyapunov Exponent, Approximate entropy and standard deviation to discriminate between 2 healthy groups in mediolateral and vertical direction and to understand the relation between local stability and complexity. In both young and older adults, mediolateral direction was less stable and less complex than vertical direction which means that mediolateral direction is more sensitive to small perturbation and it's more predictable in comparison to vertical direction. The result from linear tools shows greater variability in mediolateral direction. These results give information about the quality of gait in different age groups and may lead us in diagnosis and prognosis. View full abstract»

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  • Time series analysis of the Twinkling Artifact in color Doppler sonography for surface roughness differentiation: An in vitro feasibility study

    Page(s): 76 - 80
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (634 KB) |  | HTML iconHTML  

    Color Doppler Twinkling Artifact (TA) images acquired from the internal body stones contain coded information about the roughness level of the tissue calculi which can be used for treatment management. The TA time series however have never been mathematically studied for roughness identification. This paper investigates the feasibility of estimating the roughness level of a surface by analyzing its TA time series. The TA data of a roughness phantom was used in this study in 2 classes and 1000 TA time series were extracted for each of the classes. Then, three subsets of temporal, spectral, and wavelet features were extracted from each time series. Next, the Bayesian and Support Vector Machines (SVM) classifiers were employed for roughness differentiations. The performance of the proposed method was investigated for cross-comparison of feature subsets, classifiers, and dimension reduction efficiency. Results showed that with only first two principle components projected from the extracted features, an accuracy of 96.06% was obtained which proves the feasibility of roughness recognition by time series analysis of the TA data. View full abstract»

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  • Adaptive 3D MV beamforming in medical ultrasound imaging

    Page(s): 81 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (518 KB) |  | HTML iconHTML  

    In the recent years, volumetric imaging or 3D ultrasound imaging has been very attractive in comparison with the other diagnostic tools in medical imaging systems. In this paper, we used 2D planar array probe to obtain the RF data in order to construct the 3D image of a volume. The conventional method of beamforming in both 2D and 3D medical ultrasound imaging systems is delay and sum (DAS). We used a 2D Hanning window to simultaneously apply the Hanning window in x and y directions. DAS is a non-adaptive beamformer, then 3D adaptive minimum variance (MV) beamformer was proposed to apply to the simulated data derived from Field-II. In contrast to 3D conventional beamformer (3D DAS), adaptive 3D MV beamformer can significantly improve the imaging resolution of the simulated point targets. We implemented these beamformers in the MATLAB and survey the authenticity of them. The results illustrated that for a 32×32 elements probe with the central frequency of 3.5 MHz and sampling frequency of 20 MHz, FWHM of 3D MV beamformer for a point target is 9.36 times less than of 3D DAS beamformer and also side lobe level of 3D MV for a single point target, is 13.6dB lower than 3D DAS beamformer. It means that the resolution of 3D MV beamformer is better than 3D DAS. In order to compare the contrast of two types of beamformer, a cyst phantom was simulated in a speckle pattern. The results show that the proposed adaptive 3D MV beamformer significantly outperforms the 3D DAS. View full abstract»

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  • Controlling a drug delivery micropump using surface acoustic wave correlator

    Page(s): 87 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    A secure self-biased remote controller for precisely adjusting the micropump of a drug delivery system, working at 956 MHz, is proposed. The controller transceiver is secured by using a Barker code sequence. Surface acoustic wave device, as a bandpass filter, is designed with minimum insertion loss and a sharp bandwidth matching the single frequency of operation. In the receiver, a correlation is introduced between input codded electromagnetic wave and output Inter Digital Transducers (IDTs), creating an output voltage that electrostatically actuates the micropump diaphragm. The finite element simulation results show that the actuation voltage is a function of the coded input signal. Besides, a maximum voltage with amplitude of 5.8 V is created only at coded frequency. The generated voltage creates 9.3353 nm displacement in the conductive microdiaphragm of the micropump. View full abstract»

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