Full Research Paper
Rehabilitation Engineering
Robabe Vatanparast; Hossein Karimi; Fariba Bahrami; Roya Narimani
Volume 3, Issue 3 , June 2009, Pages 171-178
Abstract
CNS applies Anticipatory Postural Adjustments (APA) strategy to reject or minimize perturbation during different voluntary movements. The postural control mechanisms associated with voluntary arm movement (rapid arm rising) in below knee amputees (BKA) was investigated and the results were compared with ...
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CNS applies Anticipatory Postural Adjustments (APA) strategy to reject or minimize perturbation during different voluntary movements. The postural control mechanisms associated with voluntary arm movement (rapid arm rising) in below knee amputees (BKA) was investigated and the results were compared with the normal subjects. Biomechanical variables including ground reaction forces and displacements of the center of pressure were used to investigate the APA in BKA. Six below knee amputees and six control subjects stood on a force plate under three conditions: 1. with both feet on the platform, 2. with right foot (prosthetic foot) and 3. with left foot on the plate. For each condition, the task was repeated 10 times. At the same time, a camera recorded the task performance. The recorded data were used to determine the start moment of the movement. The instant at which, for the first time before starting the movement, any one of the recorded biomechanical variables deviated from its initial value was considered as the beginning of the APA. To increase the validity of the test, efforts were made to match the subjects with regards to their age, gender, cause of amputation and prosthesis types. Our results indicated that the center of pressure in the BKA participants showed greater displacements in medial-lateral and anterior-posterior directions. It was also observed that the vertical components of the ground reaction forces, when the right foot was on the plate, were increased. There were no significant differences in other biomechanical variables between the two groups. We may conclude that the voluntary arm movement perturbs the posture in the BKA participants more than in the control group. The BKA participants shifted their weight to the intact limb by the anticipation of the disturbance to avoid balance loosing. Therefore, in our study the intact limb in below knee amputee subjects played an important role in the balance control. Based on our results, we suggest considering the role of the intact limb in the rehabilitation programs and strengthening the muscles of both limbs as a major part of theses programs.
Full Research Paper
Gait Analysis
Mohsen Sadeghi Mehr; Davoud Naderi; Nader Farahpour; Saeed Davoud Abadi Farahani
Volume 3, Issue 3 , June 2009, Pages 179-187
Abstract
The present study was devoted to determine the standing human body reactions to perturbation of a base plate in the frontal plane, in order to preserve its stability. A base plate with sinusoidal fluctuation was designed and built and then markers were mounted on the specified locations on it and the ...
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The present study was devoted to determine the standing human body reactions to perturbation of a base plate in the frontal plane, in order to preserve its stability. A base plate with sinusoidal fluctuation was designed and built and then markers were mounted on the specified locations on it and the skin of subjects before testing. During testing the subjects (N=10) tried to preserve their stability against perturbations. By using Motion Analysis System, the body responses of subjects were analyzed. Using inverse dynamic methods and experimental kinematic results, forces and moments applied to the joints and between feet soles and the base plate were determined. In theoretical study, the kinematic and dynamic equations of motion of a robotic model of human body in frontal plane by using repetitive Newton-Euler method were obtained. Based on the stability of the model and supporting vertical forces criterion an object function was defined, in order to assure the stability of the model. By optimization of the object function, angle of the model joints under perturbation and its first and second derivatives were determined. The good agreement of the theoretical and experimental results states that in similar conditions a robotic model can be used instead of expensive and time-consuming experiments.
Full Research Paper
Bioheat Transfer
Mehdi Maerefat; Manije Mokhtari Dizaji; Zahra Haddad Soleimani
Volume 3, Issue 3 , June 2009, Pages 189-197
Abstract
In this paper a comprehensive mathematical model for thermal analysis of liver tissue in thermotherapy of liver cancer by laser is presented. In the present model the diffusion approximation analytical method for radiative heat transfer modeling of heat transfer process in the tissue is used for the ...
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In this paper a comprehensive mathematical model for thermal analysis of liver tissue in thermotherapy of liver cancer by laser is presented. In the present model the diffusion approximation analytical method for radiative heat transfer modeling of heat transfer process in the tissue is used for the first time. Heat transfer modeling in the biological tissue is carried out using Penes model taking into account the influence of thermal and blood perfusion coefficient fluctuations due to temperature changes as well as the effect of lipid melting on temperature distribution through enthalpy method is taken into account. In the present study the tumor is considered as a sphere with thermo-physical properties different with those of healthy tissue. Finally, the obtained non-linear equations are solved using the numerical finite volume method. Temperature distribution at several instants during the thermotherapy is calculated. The comparison of the calculated results with those of experimental results indicate a good agreement between the results. Furthermore, the effects of different parameters such as laser specifications and optic coefficient changes (through proper photopherin injection) on laser-affected area are studied using the present analytical method. These results can help the specialists in order to come upon a safe LITT method for destruction of cancerous tissues without harming the healthy ones.
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Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Hosna Ghandeharion; Abbas Erfanian Omidvar
Volume 3, Issue 3 , June 2009, Pages 199-211
Abstract
Contamination of Electroencephalographic (EEG) recordings with different kinds of artifacts is the main obstacle to the analysis of EEG data. Independent Component Analysis (ICA) is now a widely accepted tool for detection of artifact in EEG data. This component-based method segregates artifactual activities ...
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Contamination of Electroencephalographic (EEG) recordings with different kinds of artifacts is the main obstacle to the analysis of EEG data. Independent Component Analysis (ICA) is now a widely accepted tool for detection of artifact in EEG data. This component-based method segregates artifactual activities in separate sources hence, the reconstruction of EEG recordings without these sources leads to artifact reduction. Identification of the artifactual components is a major challenge to artifact removal using ICA is the. Although, during past several years, it has been proposed for automatic detecting the artifactual component, there is still little consensus on criteria for automatic rejection of undesired components. In this paper we present a new identification procedure based on statistics and time-frequency properties of independent components for fully automatic ocular artifact suppression. By comparing the statistics and time-frequency properties of independent components, the artifactual components were identified and removed. The results on 2000 4-s EEG epochs indicate that the artifact components can be identified with an accuracy of 92.8%. Moreover, statistical test indicates that the statistics and time-frequency properties of artifactual components are significantly different from that of non-artifactual components.
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Biomedical Image Processing / Medical Image Processing
Meysam Torabi; Emadoddin Fatemizadeh
Volume 3, Issue 3 , June 2009, Pages 213-225
Abstract
In this paper, an MRI-based diagnosing approach has been proposed which simultaneously analyzes T1-MR and T2-MR images. The dataset contains 120 cross-sectional images of abnormal and also normal brains as control group. Due to inherent proprieties of T1 and T2 images and their principal differences, ...
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In this paper, an MRI-based diagnosing approach has been proposed which simultaneously analyzes T1-MR and T2-MR images. The dataset contains 120 cross-sectional images of abnormal and also normal brains as control group. Due to inherent proprieties of T1 and T2 images and their principal differences, particular features have been extracted from each image. Then, more meaningful data has been structured by automatically eliminating redundant data and generating a semi-linear combination of the remaining features. Considering the fact that Alzheimer's disease mainly damages the gray and white matter of the brain and knowing that these parts of the brain can be more clearly observed in T1 images, the classifier which works under a nonlinear structure, allocates more weight for processing the T1 images comparing to T2 image. The images, after being registered, have been processed in two groups of training and test sets. According to the results, three forth of the dataset which was obtained from Harvard University's dataset (The Whole Brain Atlas) has been correctly diagnosed.
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Biological Computer Modeling / Biological Computer Simulation
Siamak Haghipour; Seyed Mohammad Reza Hashemi Golpayegani; Seyed Mohammad Firouzabadi; Sirous Momenzadeh
Volume 3, Issue 3 , June 2009, Pages 227-241
Abstract
The procedure of pain formation embarks on primary sensory neurons and then ends in central nervous system which is the first stage in the dorsal horn of the spinal cord. Nowadays the great challenge of some researchers for pain control has been to elucidate the mechanisms that are able to switch the ...
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The procedure of pain formation embarks on primary sensory neurons and then ends in central nervous system which is the first stage in the dorsal horn of the spinal cord. Nowadays the great challenge of some researchers for pain control has been to elucidate the mechanisms that are able to switch the state of the dorsal horn of the spinal cord from an unwanted state to a favorite one. In order to achieve such an aim, a model of the function of the dorsal horn of the spinal cord is extracted in order to be able to control the created pains with changing the parameters of the aforementioned model. In this study a cybernetic model is presented with the aid of bifurcation methodologies and reconstructing the dynamics linked with the process of pain formation via clinical experiment that can express different states in the dorsal horn of the spinal cord as normal, suppressed, sensitized, the functionality of memory, the effect of other primary afferents and the effect of descending signals. Input signals in this model consist of thermal stimulation degree proportional to action potential firing rate from Ab afferents, inhibitory descending signals from midbrain and inhibitory or excitatory descending signal from thalamus and cortex and the output signal is the action potential firing rate from transmission cells in dorsal horn of the spinal cord proportional to pain level have been sensed. The significant and remarkable characteristic of this model is applying a cybernetical model based on a sequence of input-output data which can obviate the drawbacks of other models in which simplification and reduction of terms reduce the operation of components of a system. On the other hand, unlike previous models which have been modeled based on membrane (slow) potential, this model is based on the action potential firing rate from transmission cells of the dorsal horn of the spinal cord that has the adaptability with cellular recording as well as having a higher accuracy.
Full Research Paper
Biomechanics of Bone / Bone Biomechanics
Shahab Mansourbaghaei; Majid Haghayegh; Seyed Mohammad Rajaei
Volume 3, Issue 3 , June 2009, Pages 243-253
Abstract
An analytical method to predict the response of the inclined impact of a fluid filled elastic spherical shell having an arbitrary thickness with an elastic toroid is investigated in this paper which can be a model for analytical evaluation of blunt impact on the human head. The study is performed under ...
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An analytical method to predict the response of the inclined impact of a fluid filled elastic spherical shell having an arbitrary thickness with an elastic toroid is investigated in this paper which can be a model for analytical evaluation of blunt impact on the human head. The study is performed under a combination of Hertzian contact theory and the local effect of membrane and bending of the shell in order to state the implicit equation to determine the transmitted force. With respect to the analytical responses, it is concluded that transmitted force decreases and contact duration increases by increasing of attack angle in constant initial velocity. In addition, closed form solution is presented to obtain impact parameters including the duration, the maximum transferred load and the maximum acceleration of the shell which particularly important for the researchers. Therefore investigation of the important quantities of the impact problem with closed form solution is possible. On the other hand, limiting cases will be discussed in next step and the concluded results are validated by finite element methods to verify the response of the model. In this step, a good agreement between analytical responses and numerical results is observed that reveals the correctness of analytical equations. In the final step of this research, obtained results are compared with experimental data.
