Sharif Digital Repository

Researchers are faced with huge challenges when undertaking BME research projects in developing countries. Various administrative, technical, economic and even cultural barriers have to be overcome whereas the quality and quantity of the output has to be comparable with the developed world in order to make results publishable. This paper uses a real project context to highlight the major problems and the necessity of a holistic approach which would take into consideration all stakeholders interests. It is only by tackling problems such as relationship between academia-industry and administration efficiency at their root that significant progress can be achieved  

Automatic cell segmentation has various applications in different parts of science. The development of automated methods for cell segmentation, remains challenging in situations where there are touching cells. In this paper we propose a new method for separating touching cells. As the first step, we use a combination of graph segmentation algorithm and thresholding for segmenting foreground objects and producing a binary image. Next, boundary points of separation zone are selected by using a corner detection algorithm. Finally, the marker controller watershed transform is applied to separate touching cells at selected points. © 2008 IEEE  

In this paper, an approximate analysis for SNR improvement factor in non-coherent integrators for communication channels is introduced. The SNR improvement factor and loss function of the non-coherent integrator are calculated. Our results are very simple and illustrative. Although calculations are with some approximations and therefore the results are not exact, but the error is negligible, as it is shown. © 2005 IEEE  

The human being in the environments of modern technology has to endure stresses of many and varied kinds of vibrations. Measuring vibration is an important tool in rehabilitation and biomechanical fields of research. We have proposed image processing as a new method to record and determine the frequency response of human body. The subjects were exposed to whole body periodical vibration while standing on a shaking table. Two digital camcorders were used to capture the motion of colored pencil-dot markers on the skin of human body (forehead) and on the edge of the shaking table. After color spotting each frame, the binary image results were processed using new circle factor criteria proposed... 

This study is conducted with the aim of validating the Saadat non-invasive blood pressure (NIBP) module accuracy and reliability against direct intra arterial pressure measurement (IBP) according to the ANSI/AAMI SP10-2002 guidelines. Measurement and comparison procedure were done in a static population of 19 adult patients with brachial catheterized arterial line with total measurements of 195 under supervision of a highly experienced cardiovascular anesthesiologist in accordance with the ANSI/AAMI SP10-2002 regulation. Data analysis was performed based on the protocol criteria. In order to represent relationships between the test device and the reference method, Bland-Altman graphical... 

A coronavirus identified as COVID-19 is the reason for an infection outbreak which is started in December 2019. NO completely effective drugs and treatments are not recognized for this virus. Recently, saffron and its compounds were used to treat different viral diseases. Saffron extract and its major ingredients have shown antiviral effects. In this study, the steered molecular dynamics simulation was used for investigating the effect of four main components of saffron that include: crocin, crocetin, safranal, and picrocrocin as candidate for drug molecules, on COVID-19. The binding energies between drug molecules and spike protein and the main protease of the virus were evaluated. The... 

An approach based pulse on contour analysis is proposed for the development of an aging index for the vascular system. The approach is non-invasive, using photoplethysmography (PPG), which is in wide clinical use. A probe is applied to the subject's finger-tip to provide a measure of the pulse waveform. The measured waveforms are filtered, digitized and post-processed. Individual pulses are extracted and the best pulse was selected by using the best pulse selection algorithm. Pulse contour analysis is then performed with specially formulated PPG fitness equation. Results of measurements taken from 72 subjects are reported. The age range of the subjects was from 19 to 68 years, all of them... 

This paper presents recent developments on effects of rest and fatigue loading on properties of healthy vertebra discs. A comparison of different approaches used in literature to study the properties of intervertebral disc is presented. The major achievements in this area so far are discussed in the context of their advantages and disadvantages. The past approaches are based on bio-mechanical models which mostly used statistical techniques for the analysis and estimation of fatigue loaded Intervertebral Disc (IVD). However, those modeling techniques were not flexible enough for analysis of customized tests. In this paper, we applied System Identification (SI) based NLARX modeling technique... 

A one dimensional model of the pulmonary arterial network along with systemic circulation was introduced to quantify the human pulmonary artery hemodynamics. A lumped parameter model of the right ventricle was used as the inlet boundary condition. A time varying elastance related the volume and pressure of the right ventricle was imposed in the model. By using a four element Windkessel model, blood flow rate throughout the right ventricle was in hand. An asymmetric structured tree was chosen as the outlet boundary conditions. Simulation was based on solving one-dimensional equations of conservation of mass and momentum by using finite volume method. Blood flow rate, pressure and velocity... 

The front part of a cell is divided to two regions called lamellum and lamellipodium (lamellipodial). This part plays an essential role for cell migration. Indeed, there are many protein filaments called actin in lamellum and lamellipodium, which induce the cell motion with polymerization in the leading edge of the cell. The actin filaments adhere to the extracellular matrix (ECM) by means of focal adhesions and they have contact by myosin motor proteins. The myosin motor proteins cause actin retrograde and anterograde flow exerted contractile stress on them. The focal adhesions exert frictional stress on the actin filaments. In this work, we developed a two-dimensional continuum model of... 

Lost sensory or motor functions can be restored using electrical neural prostheses (NP), which include surface NPs, implanted or subcutaneous NPs and the more recent Stimulus Router System (SRS). The latter type of NP outperforms the other types in its selective excitation and least invasiveness. In each case, the achieved performance depends on a multitude of design factors among which the electrical excitation waveform shape, frequency, duration of pulses, configuration of electrodes, number of intervals, thermal conditions and electrode material. To investigate the effects of these parameters on the distribution of electric current inside biological tissues, numerical modeling can be... 

The registration of images is a fundamental task in numerous applications in medical image processing. In this paper, a novel registration technique is proposed which combines landmark and intensity based approaches. In this framework, the free form deformation (FFD) is used as transformation which is the key point of our algorithm. Landmarks with FFD transformation define the guidance surface which increases robustness of intensity based registration to bias field (bias noise). In fact, the performance of registration is improved by matching both landmark and intensity information. The experimental results show that the proposed method is more accurate than only intensity based method... 

In this study, at first the cardiovascular system is modeled based on the 1D method and then the simulation of the reactive hyperemia experiment has been applied on the model. In this simulation, by applying a cuff at the brachial artery, the flow downstream of the cuff is occluded. Then with releasing the cuff immediately, a large amount of shear stress, about 4 times the basal amount, is applied downstream of the cuff and consequently to the endothelial cells in a very short moment. Considering a reported experimental transfer function between shear stress and vasodilation, the increase of the artery diameter due to the sudden increase of the shear stress is obtained. Finally, the... 

Cardiovascular diseases contribute to one third of the world's mortality and morbidity, therefore early cardiovascular disease diagnosis, treatment and monitoring has become an important market. Ideally, an early diagnosis device will need to be accurate, non-invasive, low cost and operator independent. Interestingly enough, there is a wide range of non-invasive devices available, but each with a different degree of accuracy and ease of use. In this paper, an attempt has been made to review commercially available technologies for non-invasive vascular screening. As stiffness index, reflection index, augmentation index, central aortic pressure are most commonly used to screen for vascular... 

Fuzzy Control of rowing exercise using Functional Electrical Stimulation (FES) concerns ankle, knee and hip joints. Muscular Modeling for each joint may contain two groups of muscles, namely extension and flexion. In the proposed method, joint controllers provide electrical stimulation pulses to the appropriate muscle group based on the trajectory error and according to a prescribed pattern designed for rowing exercise. Results indicate that the simulated Fuzzy control of desired angles closely match the experimental values for prescribed joints. Moreover, the robustness of the controller in presence of external disturbance is examined and the results show that the tracking of each joint... 

Modeling is one of assessing tools for better understanding of human body organs and study of diseases. One of the brain diseases is ADHD, which has been studied before, mostly by means of EEG signals. In this paper, the mean-field model, which is a model of neuron-population spiking, and the Power Spectrum of the resulting spikes have been studied by changing parameters of model. The results show that there is a meaningful relationship between firing activity of ADHD patients neuron population and the parameters of mean-field model and Power Spectrum of spikes. In addition, the effects of stimulant medications for ADHD patients on firing activity and power spectrum of firing activity of... 

Drug administration using infusion pumps can find application in treating patients with arrhythmias. These pumps can obviate the need to use drugs several times a day and automatically adapt the dosage to patient situation. Considering the importance of administration of right dosage, a perfect-controlled pump is needed to approach this goal. This paper focuses on controlling Atrial fibrillation (AF) arrhythmia. The abnormal heart rhythm that affects RR interval sequence and there have been some attempts to model these effects. One of these models is proposed by Cohen and colleges. Searching through the variables of this model, selecting the potential control variable (the one that its... 

We proposed a model to investigate the transient diffusion of drug (sulphate) into the intervertebral disc. Using finite element method, drug diffusion was simulated and the concentration of diffused drug in each region of disc including Nucleus pulpous (NP), Inner annulus fibroses (IA), and Outer annulus fibroses (OA) was measured. In addition, to investigate the role of CEP permeability on the amount of diffused drug, model was simulated with different cartilage endplate (CEP) permeability. Having obtained concentration distribution for different cases, it was clearly shown that the amount of diffused drug is affected by the endplate permeability and the more permeable CEP, the more... 

In this Paper a new approach is proposed for electrocardiogram (ECG) based human identification using wavelet distance measurement. The main advantage of this method is that it guarantees high accuracy even in abnormal cases. Furthermore, it possesses low sensitivity to noise. The algorithm was applied on 11 normal subjects and 10 abnormal subjects of MIT-BIH Database using single lead data, and a 100% human identification rate was on both normal and abnormal subjects. Adding artificial white noise to signals shows that the method is nearly accurate in SNR level above 5dB in normal subjects and 20dB in abnormal subjects  

Flow mediated dilation (FMD) measurement using ultrasound imaging (FMD-US) has been established as a standard method for assessing the endothelial function. Recently, a less skilled-operator demanding method has been proposed based on the photoplethysmogram (PPG) changes during reactive hyperemia. It was shown that the amplitude of the PPG pulse (FMD-PPG) changed in a quite similar manner to that of the artery diameter in the method of the FMD-US i.e. increases following releasing the cuff and then gradually returns to baseline. In this study PPG changes following reactive hyperaemia were modelled using time-varying passive electrical elements (R, L and C). The output of the electric analog...