Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Marziyeh Ghanavaty; Seyyedeh Fatemeh Molaeezadeh; Mojtaba Navidi
Volume 17, Issue 2 , September 2023, , Pages 150-160
Abstract
Hypertension is the leading cause of death worldwide. Continuous blood pressure (BP) measurement is crucial for the elderly and people with myocardial infarction, cardiovascular disease, kidney disease and gestational hypertension. Cuff-based blood pressure Holters are the most common method for continuous ...
Read More
Hypertension is the leading cause of death worldwide. Continuous blood pressure (BP) measurement is crucial for the elderly and people with myocardial infarction, cardiovascular disease, kidney disease and gestational hypertension. Cuff-based blood pressure Holters are the most common method for continuous blood pressure measurement, but due to the use of an inflatable cuff, they often cause discomfort, particularly during sleep. A solution to such problems is the optical measurement of blood pressure using the photoplethysmogram (PPG) signal. This paper introduces a transfer deep learning framework for estimating systolic BP (SBP) and diastolic BP (DBP) using a single PPG signal. The proposed framework consists of three main parts: 1) downsampling by a factor of 4 aimed at reducing model complexity, 2) designing a pre-trained model including CNN and BiLSTM layers, and 3) personalizing the pre-trained model for each patient through transfer learning. We carry out Bland-Altman and correlation analysis to compare our method to the invasive arterial catheter (the gold-standard BP measurement method). Our model was validated on a wide range of BP signals acquired from 100 patients in MIMIC-III database. Results showed that the error and Pearson correlation coefficient of our model are 0.14±7.38 mmHg (mean ± standard deviation) and 0.95 for SBP, and 0.00±4.67 mmHg and 0.92 for DBP. The proposed method satisfies the requirements the AAMI and IEEE-1708a standard and receives a grade A according to the BHS standard. This research has shed light on long-term BP monitoring and the prevention of cardiovascular events.
Dental Biomechanics
Pedram Akhlaghi; Setareh Khorshidparast; Gholamreza Rouhi; Hamidreza Barikani
Volume 15, Issue 2 , August 2021, , Pages 151-159
Abstract
Primary stability is the initial mechanical engagement of the implant with its neighboring bone, which can be assessed through in-vitro assessment of stiffness and the ultimate load of the bone-implant complex. Implantation and the following loading on an implant after implantation, could cause mechanical ...
Read More
Primary stability is the initial mechanical engagement of the implant with its neighboring bone, which can be assessed through in-vitro assessment of stiffness and the ultimate load of the bone-implant complex. Implantation and the following loading on an implant after implantation, could cause mechanical damage in the peripheral bone, and subsequently, reduce the primary stability of the implant. This study aimed at finding the effects of damage induced in the bone through exerting compressive loading-unloading cycles on the primary stability of the bone-implant system. For this purpose, firstly, a cylindrical bone sample was extracted from the proximal part of a bovine tibia. After implantation and bone-implant preparation, a quasi-static compressive step-wise loading-unloading cycles, with a displacement rate of 0.0024 mm/s and displacement-controlled were applied to the bone-implant structure with the amplitudes of 0.04 mm to 1.28 mm. In each step, after unloading, µCT images was captured from the bone-implant sample. Finally, the stiffness of the structure in each step and ultimate load were obtained from the mechanical test. The distribution of plastic stain in the bone due to loading-unloading of the construct was calculated using digital volume correlation, through correlating the µCT images before and after each loading step. Results of this work showed that increasing the step-wise displacement amplitude from 0 to 0.96 mm caused a stiffness reduction of 40%, compared to the initial stiffness. Also, the digital volume correlation results showed that maximum plastic strain occurred in the neighboring bone in the crestal part of dental implant, and also increasing loading amplitude from 0.64 to 0.96 mm led to 1.5% increase in the maximum plastic strain. It is hoped that results of this kind of investigation can be helpful in optimizing the dental implants design, with the approach of increasing their stability.
Dental Biomechanics
Jalil Rezaei Pajand; Seyed Mohammad Chavoshi
Volume -1, Issue 2 , June 2005, , Pages 153-158
Abstract
The main objective of this study is to present a mathematical model for frictional forces in orthodontic tooth movements. In order to produce lighter and more efficient sliding movement, good estimation of frictional forces must be determined. For the purpose of analysis, a typical bracket with a circular ...
Read More
The main objective of this study is to present a mathematical model for frictional forces in orthodontic tooth movements. In order to produce lighter and more efficient sliding movement, good estimation of frictional forces must be determined. For the purpose of analysis, a typical bracket with a circular cross section arch wire is considered with a view to examine the effect of ligation technique (shape), geometry and properties of ligature, and arch wire on the friction forces between ligature and arch wire. Both uniform and non-uniform distributions of contact forces are considered. The result presented herein indicated that, for circular orthodontic arch wires, friction force between ligature and wire is proportional to tensile force in elastomeric ligature. This force is depended on the shape of ligation, material properties and geometries of wire, bracket and ligature.
Fluid-Structure Interaction in Biological Media / FSI
Ali Vazifedoost Saleh; Nasser Fatouraee; Mahdi Navidbakhsh; Farzad Izadi
Volume 11, Issue 2 , June 2017, , Pages 153-165
Abstract
In terms of mechanical behavior, human’s speaking and generating voice is a sophisticated process which is resulted in interaction between flowing air through the larynx and oscillating functionality of vocal folds. The sulcus vocalis is one of the individual cases of scarring in which the superficial ...
Read More
In terms of mechanical behavior, human’s speaking and generating voice is a sophisticated process which is resulted in interaction between flowing air through the larynx and oscillating functionality of vocal folds. The sulcus vocalis is one of the individual cases of scarring in which the superficial lamina propria is absent over the length of the vocal fold and can procreate several disorders in voice generation. In this study, for the first time, the effects of sulcus vocalis on vibrating functionality of vocal folds have been assessed by employing finite element numerical modeling. Two-dimensional models of either healthy or sulcus vocal folds were implemented which each one is coupled and solved via LS-dyne software. Also, the three e-layer linear elastic model was utilized for the structure phase and the arbitrary Lagrangian-Eulerian (ALE), incompressible continuity, and Navier- Stokes relations were used for the fluid domain. Type II patients’ self-excited oscillations have been exhibited and compared with the healthy model. The results of the healthy model were assessed and compared with numerical and experimental results of previous studies. Moreover, the influences of the sulcus not only on the flow components but also on the oscillating functionality of the vocal folds have been evaluated. The results indicated that the frequency of vocal folds’ vibrations and the value of volume flux tends to be remarkably declined and boosted up respectively.
Zeinab Tashakorizade; Nadia Naghavi; Seyed Kamal Hosseini Sani
Volume 8, Issue 2 , June 2014, , Pages 159-171
Abstract
Nature of the system, a novel adaptive control structure has been proposed for time-delayed systems, which is a combination of the model reference adaptive control with modified Smith Predictor. Due to extensive variability among patients in metabolism, an in silico trial consisting of 30 patients with ...
Read More
Nature of the system, a novel adaptive control structure has been proposed for time-delayed systems, which is a combination of the model reference adaptive control with modified Smith Predictor. Due to extensive variability among patients in metabolism, an in silico trial consisting of 30 patients with random changes and sinusoidal oscillation in parameters of Dalla Man glucose-insulin model has been used to simulate the personal variability in the glucose control system. Performance of the proposed algorithm has been compared to the PID controller with Smith Predictor, based on the quantitative and qualitative indicatirs. Simulation results show that the proposed control scheme is effective in fasting conditions, meal disturbance rejection, and robustness against inter-patients variability.Insulin therapy for type 1 diabetes patients often causes high fluctuations in their blood glucose and hypoglycemic/hyperglycemic events. Closed loop control of blood glucose using artificial pancreas can improve life quality of patients. In this paper, physiological behaviour of the system has been modeled inversely using daily patient data acquired GIM simulator. Then, considering the delaed.
Biomechanics / Biomechanical Engineering
Hadi Nickbakht; Seyyed Yousef Ahmadi Brooghani; Vahid Arbabi
Volume 16, Issue 2 , September 2022, , Pages 159-166
Abstract
In a varus knee, the load balance on two sides of the knee joint is disturbed and the stress applied to the medial side of the joint will be greater than that of a healthy knee. Such a case is often progressive and gradually leads to wear and pain. In this study, the finite element model for two 3D samples ...
Read More
In a varus knee, the load balance on two sides of the knee joint is disturbed and the stress applied to the medial side of the joint will be greater than that of a healthy knee. Such a case is often progressive and gradually leads to wear and pain. In this study, the finite element model for two 3D samples of healthy knee joint and varus knee in standing position was generated from MRI images and after loading and solving the problem, the stress distribution status in menisci and cartilage is obtained for both modes. The obtained results show the difference in maximum stresses and the difference in the shape of stress distribution areas. The results also show that the maximum values of von Mises stress and also the contact pressure in the inner area of the knee for the varus knee are much higher values compared to a healthy knee. In the standing position, the maximum contact pressure in the inner area of the joint, under a 400 N load applied to the upper end of the femoral head, was obtained 4.527 and 7.821 MPa for a healthy knee and varus, respectively. For maximum values of von Mises stress, 2.821 and 6.501 MPa was obtained respectively. Due to the results and differences in stresses, the need for surgery to balance the stresses and loads on two sides of the knee is essential for a patient with varus knees. The amount of correction can be determined in addition to examining the joint geometry by examining the differences in stresses on both sides of the joint in a more accurate way.
Fluid-Structure Interaction in Biological Media / FSI
Mahdi Moradkhani; Bahman Vahidi
Volume 9, Issue 2 , July 2015, , Pages 179-190
Abstract
Investigating the mechanical stimuli on stem cells under in vitro and in vivo conditions is a very important topic to achieve an ability tocontrol the cellular responses like growth, proliferation and differentiation. Many investigations carried out about biomechanical factors involved in this phenomenon ...
Read More
Investigating the mechanical stimuli on stem cells under in vitro and in vivo conditions is a very important topic to achieve an ability tocontrol the cellular responses like growth, proliferation and differentiation. Many investigations carried out about biomechanical factors involved in this phenomenon and nowadays, it is proved that some factors like as cell morphology, subcellular elements configuration, scaffold architecture, substrate stiffness and mechanical stimulation via substrate displacement or fluid flow, have got an important effecton cellular responses. In this study, we have tried to evaluate the responses of a stem cell to the stiffness and thickness of the substrate by the means of finite element method. For this purpose, we have used collagen-based scaffolds as the artificial ECM and a cell culture in a bioreactor with fluid flow was simulated. By use of fluid-structure interaction method and solving the equations in two-way coupling scheme, the results show that the increase in thickness and stiffness of the substrate will result in15 percent change in cell-substrate stresses, respectively. Also, it was seen that the change of substrate stiffness only in the range of 0.1-100 KPa could affect the cell response to an external stimulation. These results, along with other similar investigations, could be used as an instructor by the researchers to optimize the stem cell’s microenvironment in vitro, and finally get the most out of their stem cell related Investigations.
Speech processing
Mohammad Reza Yazdchi; Seyed Ali Seyed Salehi
Volume 1, Issue 3 , June 2007, , Pages 201-213
Abstract
One of the most important challenges in automatic speech recognition is in the case of difference between the training and testing data. To decrease this difference, the conventional methods try to enhance the speech or use the statistical model adaptation. Training the model in different situations ...
Read More
One of the most important challenges in automatic speech recognition is in the case of difference between the training and testing data. To decrease this difference, the conventional methods try to enhance the speech or use the statistical model adaptation. Training the model in different situations is another example of these methods. The success rate in these methods compared to those of cognitive and recognition systems of human beings seems too much primary. In this paper, an inspiration from human beings' recognition system helped us in developing and implementing a new connectionist lexical model. Integration of imputation and classification in a single NN for ASR with missing data was investigated. This can be considered as a variant of multi-task learning because we train the imputation and classification tasks in parallel fashion. Cascading of this model and the acoustic model corrects the sequence of the mined phonemes from the acoustic model to the desirable sequence. This approach was implemented on 400 isolated words of TFARSDAT Database (Actual telephone database). In the best case, the phoneme recognition correction increased in 16.9 percent. Incorporating prior knowledge (high level knowledge) in acoustic-phonetic information (lower level) can improve the recognition. By cascading the lexical model and the acoustic model, the feature parameters were corrected based on the inversion techniques in the neural networks. Speech enhancement by this method had a remarkable effect in the mismatch between the training and testing data. Efficiency of the lexical model and speech enhancement was observed by improving the phonemes' recognition correction in 18 percent compared to the acoustic model.
Biomedical Image Processing / Medical Image Processing
Amin Mohammadian; Hasan Aghaeinia; Farzad Towhidkhah
Volume 6, Issue 3 , June 2012, , Pages 207-218
Abstract
In this paper, a method is proposed based on the prior knowledge from a new subject to improve the performance of person-independent facial expression recognition. First, in order to obtain a basic system, a combination of geometric features and texture descriptor is compared with global features (i.e., ...
Read More
In this paper, a method is proposed based on the prior knowledge from a new subject to improve the performance of person-independent facial expression recognition. First, in order to obtain a basic system, a combination of geometric features and texture descriptor is compared with global features (i.e., mapped face images using the Kernel-PCA and raw data of face images). The results of comparison under noisy conditions were investigated and evaluated by person-dependent/independent cross-validation method. The obtained basic system was evaluated by leave-one-subject-out cross-validation. Since the same subjects are not introduced in both training and test phases, the basic recognition system is person-independent and its performance is substantially lower than that of person-dependent cross-validation case. To improve the performance of the basic system, a method is proposed in which virtual samples are generated based on the prior knowledge from the new subject and are used in learning process. The results show that the recognition rate increases up to 96% for the person-dependent basic system, kernel-PCA method is more sensitive than the others to interpersonal variability, and the recognition rate is significantly (P<0.05) improved up to 91.39% compared to that of person-independent case.
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, ...
Read More
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.
Biomedical Image Processing / Medical Image Processing
Saeed Kermani; Hamid Abrishami Moghaddam; Mohammad Hasan Moradi
Volume 2, Issue 3 , June 2008, , Pages 215-231
Abstract
This paper presents a new method for quantification analysis of left ventricular performance from the sequences of cardiac magnetic resonance imaging using the three-dimension active mesh model (3DAMM). AMM is composed of topology and geometry of L V and associated elastic material properties. The ...
Read More
This paper presents a new method for quantification analysis of left ventricular performance from the sequences of cardiac magnetic resonance imaging using the three-dimension active mesh model (3DAMM). AMM is composed of topology and geometry of L V and associated elastic material properties. The LV deformation is estimated by fitting the model to the initial sparse displacements which is measured by a new establishing point correspondence procedure. To improve the model, a new shape-based interpolation algorithm was proposed for reconstruction of the intermediate slices. The proposed approach is capable of estimating the displacement field for every desired point of the myocardial wall. Then it leads to measure dense motion field and the local dynamic parameters such as Lagrangian strain. To evaluate the performance of the proposed algorithm, eight image sequences (six real and two synthetic sets) were used and the findings were compared with those reported by other researchers. For synthetic image sequence sets, the mean square error between the length of motion field estimated by the Algorithm and the analytical values was less than 0.5 mm. The results showed that the strain measurements of the normal cases were generally consistent with the previously published values. The results of analysis on a patient data set were also consistent with his clinical evidence. In conclusion, the results demonstrated the superiority of the novel strategy with respect to our formerly presented algorithm. Furthermore, the results are comparable to the current state-of-the-art methods.
Saeed Rashidi; Ali Fallah; Farzad Towhidkhah
Volume 4, Issue 3 , June 2010, , Pages 219-230
Abstract
Nowadays, fast and accurate algorithms for signature verification are very attractive. In the area of dynamic signature verification, the features are classified into two groups: parametric and functional features. In parametric algorithms, although the speed of features extraction and classification ...
Read More
Nowadays, fast and accurate algorithms for signature verification are very attractive. In the area of dynamic signature verification, the features are classified into two groups: parametric and functional features. In parametric algorithms, although the speed of features extraction and classification process is faster than function based approaches but they are less accurate. The goal of this paper is modeling of the velocity signal that its pattern and properties are stable for a person. With using pole-zero models based on discrete cosine transform, a precise method is proposed for modeling and then features are extracted from strokes. These features are the deference of pole angles of strokes. Applying linear, parzen window and support vector machine classifiers, the proposed algorithm was tested on data set from Persian, Chinese, English and Turkish people and with common threshold, resulted equal error rates of 1.25% and 1.78% in the random and skilled forgeries, respectively.
Medical Instrumentation
Zahra-Sadat Fatemi; Mohammad Mahdi Ahmadi
Volume 12, Issue 3 , November 2018, , Pages 221-234
Abstract
The use of smart medical implants to study the human brain and the interaction of neurons with each other has recently gained much attention. These implants contain microelectrode arrays in which the size of an electrode is in the order of the size of a neuron; therefore they allow recording signals ...
Read More
The use of smart medical implants to study the human brain and the interaction of neurons with each other has recently gained much attention. These implants contain microelectrode arrays in which the size of an electrode is in the order of the size of a neuron; therefore they allow recording signals from single neuron or stimulating a single neuron with considerable precision. Design of such implants entails many challenges, one of which is the design of power and data recovery blocks. In this paper, we describe the design of a new power and data recovery unit for an implantable neural stimulating microsystem. The power recovery unit generates two supply voltages: a 1.8-V supply for the core circuits and a higher supply voltage for the stimulation front-end. An active rectifier is used to generate the 1.8-V supply. The active rectifier achives a 89% power conversion efficiency and 150mV voltage drop with a 3-V sinusoidal input voltage. In order to maximize the efficiency of the stimulation front-end, the supply voltage of that circuit should be adaptively adjusted according to the amplitude of the stimulation current. As a result, a phase-controlled active rectifier is utilized to generate the supply voltage for the neural stimulation front-end. The phase-controlled active rectifier can generate out voltages ranging from 1.8V to 2.5V. Using phase-controlled active rectifier can increase the power conversion efficiency up to 50%. In addition to power recovery, neuroelectrical stimulation microsystems should receive stimulation data from outside of the body. Hence, this paper also circuits required for clock and daterecovery. The data recovery block is able to demodulate the ASK-modulated signal with 3-V to 5-V amplitude and 5% to 25% modulation index.
Biomedical Image Processing / Medical Image Processing
Maryam Momeni; Hamid Abrishami Moghaddam; Reinhard Grebe; Kamran Kazemi; Fabrice Wallois
Volume 5, Issue 3 , June 2011, , Pages 231-244
Abstract
Reliable gradation of neonatal brain development is important for clinical investigation of neurological disorders. A prerequisite for such quantification of development is knowledge about an appropriate temporal resolvability. For this purpose, we investigated the evolution of macroscopic morphological ...
Read More
Reliable gradation of neonatal brain development is important for clinical investigation of neurological disorders. A prerequisite for such quantification of development is knowledge about an appropriate temporal resolvability. For this purpose, we investigated the evolution of macroscopic morphological features of the neonatal brain to estimate, for the first time, the required temporal interval in the early weeks after birth. In a first step, we constructed two neonatal templates for the age ranges of 39-40 and 41- 42 weeks' gestational age using T1-weighted MR images. We compared the spatial variation of anatomical landmarks and the average and the maximal length of spatial deformation in 25 subjects normalized to the two templates along x, y and z directions. MANOVA confirmed the significant difference between spatial variations of the above macroscopic features in the two age ranges. Furthermore, quantitative analysis of feature scattering yielded the same result even in features for which the null hypothesis was not rejected by MANOVA. We conclude that minimal temporal interval of two weeks is required for acute macroscopic morphological studies of the developing brain in the early weeks after birth.
Biomedical Image Processing / Medical Image Processing
Pedram Masaeli; Hamid Behnam; Zahra Alizadeh Sani; Ahmad Shalbaf
Volume 7, Issue 3 , June 2013, , Pages 237-254
Abstract
Coronary artery diseases cause more than half of all deaths in the world. Obviously, early identification is an important way to control coronary artery disease that is diagnosed by measurement and scoring general and regional movement of left ventricle of heart (Normal, Hypokinetic and Akinetic). The ...
Read More
Coronary artery diseases cause more than half of all deaths in the world. Obviously, early identification is an important way to control coronary artery disease that is diagnosed by measurement and scoring general and regional movement of left ventricle of heart (Normal, Hypokinetic and Akinetic). The most common method of imaging the heart using ultrasound is called echocardiography. Using this method accurate view of the heart walls, valves and beginning of main arteries can be obtainbed. Due to the difficulty for the interpretation of these images, time consumption and errors in manual analysis methods, an automated analysis method is required. In this paper we calculate the displacement field in a cycle of heart motion from two-dimensional echocardiography images. To do this, a frame is usually chosen as the reference frame and then all images in a cycle are mapped to it with a mathematical equation. The main idea is to find a semi-local spatiotemporal parametric model for deformation created in a cardiac cycle with nonrigid registration using B-spline functions; as an optimization problem that effectively corrects differences due to movements by minimizing the difference between current frame and a reference frame. Motion estimation accuracy is measured using the sum of squares differences. We use gradient-descend algorithm and multiresolution method to acquire the coefficients in the motion model. The accuracy of the proposed method is assessed using a synthesis sequence of cardiac cycles produced with the simulation software Field II. This algorithm can be applied for the clinical analysis of regional left ventricle then movement parameters and threshold values for the scoring of each section can be extracted. The algorithm represents significant difference between a part of the normal heart and unhealthy heart that shows potential of clinical applications of the proposed method.
Human Computer Interaction / HCI
Bita Salimi Qadi; Mehdi Golsorkhtabaramiri
Volume 11, Issue 3 , September 2017, , Pages 243-254
Abstract
Wireless body area networks (WBANs) are specific kinds of wireless sensor network which have been widely used in many areas, especially for health monitoring in the areas of health services and healthcare. Among the most important challenges concerning these networks are performance, high throughput ...
Read More
Wireless body area networks (WBANs) are specific kinds of wireless sensor network which have been widely used in many areas, especially for health monitoring in the areas of health services and healthcare. Among the most important challenges concerning these networks are performance, high throughput and increasing network lifespan. One of the possible ways to increase network lifetime is to use energy harvesting possibility. In energy harvesting WBANs, the energy of the sensor nodes does not end, but upon reaching a threshold, the node goes into a power-consuming mode and becomes blocked and does not participate in the network operation until it reaches the required energy. In this paper, an energy-efficient routing protocol for energy harvesting WBANS is proposed. In this protocol, the medical sensor nodes on the patient's body have the ability of energy harvesting while the routing method and transmitter node are used to transfer data from sensor nodes to the sink. This method uses single hob routing when the distance between the sensor node and the sink is less than that of the sensor node to the transmitter node. Also, if emergency data is detected, a single hob routing is used to send data, otherwise, multi hob routing is used to do so. Also, to increase throughput during energy harvesting, the sensor node does not block, but sends the data to its nearest neighbor. This protocol has been able to improve network throughput and lifetime. We used energy harvesting to increase network lifetime and routing techniques to reduce energy consumption.
Bioheat Transfer
Farshad Bahramian; Afsaneh Mojra
Volume 10, Issue 3 , October 2016, , Pages 245-256
Abstract
The aim of this study is to investigate the use of thermography technique for detection of thyroid gland embedded in the neck through a numerical and an experimental approach. To this end, a real 3D model of the human neck and its primary organs including trachea, thyroid gland, common carotid artery ...
Read More
The aim of this study is to investigate the use of thermography technique for detection of thyroid gland embedded in the neck through a numerical and an experimental approach. To this end, a real 3D model of the human neck and its primary organs including trachea, thyroid gland, common carotid artery and internal jugular vein is constructed based on the computerized tomography (CT) scan images of a healthy case and a case of thyroid cancer. The model is used for analyzing bio-heat transfer in the neck. In the thermal analysis the thyroid gland is considered as a heat source via specific function that generates heat based on the thyroid temporal temperature. Moreover, external convection through the neck skin surface and the ambient air, an internal convection through the inner layer of trachea and breathed air and heat transfer through the artery and the vein are considered. The result is the temperature distribution (thermogram) on the skin surface of the neck which reveals an approximate 0.5 -1.4 ˚C temperature increase on the area above thyroid gland for the healthy case. Studying effects of the thyroid cancer on the thermogram shows an approximate 0.7 -1.6 ˚C temperature increase due to the increased metabolic rate of the cancerous tumor compared to the healthy tissue. In order to practically investigate the applicability of thermography technique, a healthy case is examined by a high precision thermographic camera in similar conditions to the numerical simulation. Similar temperature increase due to the existence of the thyroid gland by the simulation and experiment affirmed the capability of the thermography method in the thyroid gland detection on the skin surface of the neck.
Seyedeh Somayeh Naghibi; Ali Fallah; Ali Maleki; Farnaz Ghassemi
Volume 13, Issue 3 , October 2019, , Pages 247-257
Abstract
The correct prediction of the optimal motor trajectory is necessary for movement rehabilitation and control systems such as functional electrical stimulation and robotic therapy. It seems that human reaching movements are composed of a set of submovements, each of which is a correction of the overall ...
Read More
The correct prediction of the optimal motor trajectory is necessary for movement rehabilitation and control systems such as functional electrical stimulation and robotic therapy. It seems that human reaching movements are composed of a set of submovements, each of which is a correction of the overall movement trajectory. Therefore, it is possible to interpret complex movements, learning, adaptability and other features of the motion control system using submovements. The purpose of this study is predicting and generating planar reaching movements using a realistic model similar to the actual mechanism of human movement and based on the submovement. The data used consists of different replications of four types of planar movement Performed by three healthy subjects. After the preprocessing and phasing, the movements decomposed to minimum-jerk submovement. In the next step, the training of three distinct neural networks was carried out to learn the submovement parameters including the amplitude, duration, and initiation time. Finally, the ANNs were combined to form a closed-loop model that generated accurate reaching movements based on the error correction. The target access rate for all predicted movements by the closed loop model was 100%. Also, the mean distance to the target, the VAF, and the mean MSE error between the predicted and main movement trajectory showed that the predicted movements are a good approximation of the main movements. The results showed that when trained neural networks with submovements, were placed in a closed loop model, they were able to predict proper submovements for complete access to targets due to the compensation of propagated errors from the previous steps. The results of this study can be used to improve motor rehabilitation methods.
Targeted Drug Delivery / Smart Drug Delivery / Drug Targeting
Fariba Ganji; Fateme Hoobakht; Farzane Ghasemi Tahrir; Ebrahim Vasheghani-Farahani
Volume 8, Issue 3 , September 2014, , Pages 249-260
Abstract
Somanis one of the strongest nerve agents and treatment of poisoning with Soman is difficult and time-critical. Pyridostigmine bromide is an inhibitor of cholinesterase used for protecting against toxicity by Soman. In this study, a new injectable thermosensitive sustained release dosage form of pyridostigmine ...
Read More
Somanis one of the strongest nerve agents and treatment of poisoning with Soman is difficult and time-critical. Pyridostigmine bromide is an inhibitor of cholinesterase used for protecting against toxicity by Soman. In this study, a new injectable thermosensitive sustained release dosage form of pyridostigmine bromide was achieved by chitosan/glycerolphosphate solution. In this study, thermosensitivity and rheological properties of chitosan solution (2% w/v) in aqueous hydrochloric acid (0.1 molar) with different percent of glycerolphosphate salt as well as the release profile of pyridostigmine bromide have been investigated. It was observed that increasing the glycerolphosphate salt concentration would increase the pH of chitosan solution, while decrease its gelation time and loss or storage modulus. It was also observed that glycerolphosphate salt concentration has direct effect on hydrogel thermoreversibility. The presented results indicated that hydrogel containing 2% w/v of chitosan and 16% w/v of glycerolphosphate salt could sustain the delivery of pyridostigmine bromide, through Fickian diffusion, up to four days.
Bioelectrics
Zohre Mojiri; Amir Akhavan; Ehsan Rouhani
Volume 16, Issue 3 , December 2022, , Pages 257-269
Abstract
Deep brain stimulation (DBS) is a technique to stimulate the deep areas of the brain which can be used in both invasive and non-invasive methods. In invasive DBS, the electrodes are surgically implanted inside the brain to achieve the desired depth of the stimulation. The invasive DBS approach suffers ...
Read More
Deep brain stimulation (DBS) is a technique to stimulate the deep areas of the brain which can be used in both invasive and non-invasive methods. In invasive DBS, the electrodes are surgically implanted inside the brain to achieve the desired depth of the stimulation. The invasive DBS approach suffers from intracranial bleeding. One solution is using non-invasive DBS by temporal interference (TI) method. In TI stimulation, the constructive interference of two electric fields generated by two high-frequency sinusoidal currents increases the stimulation intensity at a certain depth. The objective of this paper is to investigate quantitatively as well as qualitative analysis of TI stimulation effect on the activation of primary motor cortex area of the rat. To this end, a 4-channel stimulator is used. The experiment is conducted on one anesthetized rat. The transcranial stimulation is applied by the electrode fixed on the skull with screw and the results are evaluated qualitatively and the quantitatively in the domains of time, frequency, and space. To quantify the results, a three-axis accelerometer sensor is used to record the movement acceleration of the right hand. The results showed that, the variation of the stimulation parameters (stimulation current intensity, frequency difference and ratio of currents of the two electrodes) changed the stimulation area inside the two hemispheres of the brain and movement range of the right hand. Moreover, the relationship between the difference frequency of the stimulation of the two pairs of electrodes and the range of motion was analyzed using a three-order polynomial regression model.
Seyed Hojat Sabzpoushan; Azadeh Ghajarjazy
Volume 9, Issue 3 , December 2015, , Pages 267-282
Abstract
Time constant is a physical concept that one may deduce the speed of response and reaction of a system from it. Experimental findings confirm the dependency of the speed of opening-closing of ionic channels to the membrane voltage. In this paper a model for time constant of membrane voltage in neurons ...
Read More
Time constant is a physical concept that one may deduce the speed of response and reaction of a system from it. Experimental findings confirm the dependency of the speed of opening-closing of ionic channels to the membrane voltage. In this paper a model for time constant of membrane voltage in neurons has been presented. At first, the presented model has been established as a theorem and then the theorem has been proved. According to the presented theorem, one can simulate different morphology and time course of action potential (AP) in neurons by adjusting the model parameters. The validation of the presented theorem (model) has been shown by simulation examples of some kinds of neurons and cells APs. Regarding the generality of the presented theorem, our model not only can be applied in biomedical systems but also it may be used in any physical systems.
Robotic Surgery / Robot-Assisted Surgery
Mohadese Yaryan; Mahyar Naraghi; Seyed Mehdi Rezaei; Mohammad Zareinejad; Hamed Ghafarirad
Volume 6, Issue 4 , June 2012, , Pages 287-297
Abstract
This paper addresses a new control scheme for bilateral telesurgical system with flexible links surgical robot. In this regard, hybrid structure of feedback and feedforward controller is suggested for flexible slave robot. This approach utilizes capability of Input Shaping (IS) as feedforward controller ...
Read More
This paper addresses a new control scheme for bilateral telesurgical system with flexible links surgical robot. In this regard, hybrid structure of feedback and feedforward controller is suggested for flexible slave robot. This approach utilizes capability of Input Shaping (IS) as feedforward controller to reduce vibration at robot’s end tip and the feedback controller based on collocated Proportional-Derivative (PD) for control rigid body motion of the system. Stability of closed loop input shaper for nonlinear systems is discussed for the first time in this article. The stability conditions for overall system with constant communication time delay are derived using lyapunov method. Due to the independence of the system parameters, combination of these controllers results stability robustness to parameter uncertainties. Moreover, It is shown that reshaped master command to slave’s controller improves tracking performance in the presence of robot flexibility. Simulation results are used to verify the main theoretical points of this paper and demonstrate the effectiveness of proposed control framework in terms of input tracking and vibration suppression.
Tissue Engineering
Mehdi Navidbakhsh; Milade Jafarnejad
Volume 3, Issue 4 , June 2009, , Pages 299-306
Abstract
The cancer changes the cytoskeleton of the cells .This change has some effects on the cell mechanobiology and will lead to some changes in the deformability of the cells. The moving ability of the cancer cells would be more than healthy cells. Thus, they can migrate through the tissue in human body. ...
Read More
The cancer changes the cytoskeleton of the cells .This change has some effects on the cell mechanobiology and will lead to some changes in the deformability of the cells. The moving ability of the cancer cells would be more than healthy cells. Thus, they can migrate through the tissue in human body. In this survey, a valid FEM of a cancer cell is presented. Then the effects of various factors such as membrane thickness, elasticity, strain, and frequency response are studied during a process of being converted from normal cells into cancerous malignant cells. Besides, the initial mathematical models are provided. The results clarify that an increase in membrane elasticity, strain, and frequency would lead to increase in the reaction force. However, an increase in the membrane thickness decreases the reaction force.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Masoud Reza Aghabozorgi Sahaf
Volume 1, Issue 4 , June 2007, , Pages 301-310
Abstract
The extraction of the fetal electrocardiogram (FECG) from the skin electrode signals recorded of the mother's body is a problem of concern to signal processing. Blind signal separation (BSS) technique that separates some signals from their combinations without acknowledgments about transmission channel, ...
Read More
The extraction of the fetal electrocardiogram (FECG) from the skin electrode signals recorded of the mother's body is a problem of concern to signal processing. Blind signal separation (BSS) technique that separates some signals from their combinations without acknowledgments about transmission channel, is a fundamental method for solving this problem. The most proposed BSS algorithm for separation of fetal electrocardiogram (FECG) and mother electrocardiogram (MECG) relies on the independence of these signals (ICA). This paper introduces a novel technique for the cases that signals are correlated with each other, i.e. considering a real assumption. The method uses Wold decomposition principle for extracting the desired and proper information from the predictable part of the measured data, and exploits approaches based on the second-order statistics to estimate source signals. Simulation results are showed the effectiveness of the method for separation of electrocardiogram signals.
Biomedical Image Processing / Medical Image Processing
Mohammad Hasan Moradi; Mohammad Sajad Manuchehri; Reza IraniRad
Volume 5, Issue 4 , June 2011, , Pages 313-331
Abstract
During the centuries, palpation has always been a crucial procedure in diagnosing the diseases. At first, these procedures were invasive, but nowadays numerous attempts by the name of elastographyhave been madeforreaching to noninvasive methods. Elastographys basic datais tissues relative displacement ...
Read More
During the centuries, palpation has always been a crucial procedure in diagnosing the diseases. At first, these procedures were invasive, but nowadays numerous attempts by the name of elastographyhave been madeforreaching to noninvasive methods. Elastographys basic datais tissues relative displacement which is tracked by ultrasound waves. First in these systems in order to attain the displacements gradient, an image of tissue is taken and then it is compared to image of that same tissue after applying a small mechanical impulse into it. Mechanical strain is calculated by estimating the displacements gradient and demonstrated as an image with gray levels named elastogram (strains image) .Based on how the mechanical vibration is given, ultrasound-elastography will separate into four categories as follows: static, dynamic, shear-wave and passive elastography. In static-elastography, the force is applied manually by the clinician and therefore it depends on operators skill and cannot be considerable. In dynamic type the movement of tissue is constantly provided by an external vibrator, so in order to prevent the interference of impulses we must use a rapid imaging system that eventually will cost extra expense and unavailability. Shear-wave elastography which currently is the most common method used in elastography systems,has an external vibratorLike dynamic method, but due to momentary impulses, it skips the problem of impulse interference. In passive method, physiologic movements of body will be given to tissue as itsvibration. This technique is hypothetical yet.
