Journal of Biomedical Physics & Engineering
Volume:4 Issue: 1, Jan-Feb 2014

Numerical study of angulation effects of renal arteries on blood flow has been of great interest for many researchers. This paper aims at numerically determining the angulation effects of stenosed renal arteries on blood flow velocity and renal mass flow. An anatomically realistic model of abdominal aorta and renal arteries is reconstructed from CT-scan images and used to conduct numerical simulation of pulsatile non-Newtonian blood flow incorporating fluid-structure interaction. The renal arteries in the realistic model have left and right branch angles of 53° and 45°, respectively. Atrapezium shape stenosis is considered in the entrance of right renal artery. Two other branch angles, i.e. 90° and 135°, are also considered for right renal artery to study the angulation effects. Comparison between models with right renal branch angles of 45°, 90° and 135° reveals that high curvature of streamlines in the entrance of the renal artery with the angle of 135˚ causes the flow velocity and renal mass flow to be less than those of 45˚and 90˚. It is concluded that large renal branch angles cause the arteries to be unable to deliver blood in the requisite amounts to kidney. Kidney responds to counteract low blood flow by activating the renin-angiotension system which leads to severe hypertension.

Sun protection materials have been one of the major concerns in pharmaceutical industry since almost one century ago. Various materials have been found to have such an effect but there are still many unknown substances that have not been discovered. To introduce a novel mineral-based sun lotion with considerable UV absorption properties compared to commercially available sunscreens. UV absorption properties of transparent plastic sheets covered by a uniform cream layer of different mineral-based sun lotions and a commercially available sun lotion were tested. Sun lotions containing specific proportion of bentonite and zeolite minerals were capable of absorbing the highest level of UV light compared to that of the commercially available sun lotion. Mineral-based sun lotions can be considered as cost effective alternatives for current commercial sunscreens

Accurate brain tissue segmentation from magnetic resonance (MR) images is an important step in analysis of cerebral images. There are software packages which are used for brain segmentation. These packages usually contain a set of skull stripping, intensity non-uniformity (bias) correction and segmentation routines. Thus, assessment of the quality of the segmented gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) is needed for the neuroimaging applications. In this paper, performance evaluation of three widely used brain segmentation software packages SPM8, FSL and Brainsuite is presented. Segmentation with SPM8 has been performed in three frameworks: i) default segmentation, ii) SPM8 New-segmentation and iii) modified version using hidden Markov random field as implemented in SPM8-VBM toolbox. The accuracy of the segmented GM, WM and CSF and the robustness of the tools against changes of image quality has been assessed using Brainweb simulated MR images and IBSR real MR images. The calculated similarity between the segmented tissues using different tools and corresponding ground truth shows variations in segmentation results.Comparison with Existing A few studies has investigated GM, WM and CSF segmentation. In these studies, the skull stripping and bias correction are performed separately and they just evaluated the segmentation. Thus, in this study, assessment of complete segmentation framework consisting of pre-processing and segmentation of these packages is performed. The obtained results can assist the users in choosing an appropriate segmentation software package for the neuroimaging application of interest.

One of the main problems especially in operating room and monitoring devices is measurement of Blood Pressure (BP) by sphygmomanometer cuff. In this study we designed a new method to measure BP changes continuously for detecting information between cuff inflation times by using vital signals in monitoring devices. This will be achieved by extraction of the time difference between each cardiac cycle and a relative pulse wave. Finger pulse and ECG signals in lead I were recorded by a monitoring device. The output of monitoring device is inserted in a computer by serial network communication. A software interface is used to display and process the signals in the computer. Time difference between each cardiac cycle and pulse signal was calculated throughout R wave detection in ECG and peak of pulse signal by the software. The relation between time difference in two waves and BP was determined then the coefficients of equation were obtained in different physical situations. The results of estimating BP were compared with the results of sphygmomanometer method and the error rate was calculated. In this study, 25 subjects participated among them 15 were male and 10 were female. The results show that BP is linearly related to time difference. Average of coefficient correlation is 0.9±0.03 for systolic and 0.82±0.04 for diastolic blood pressure. The highest error percentage was calculated 8% for male and 11% for female group. Significant difference was observed between the different physical situation and arm movement changes. The relationship between time difference and age was estimated in a linear relationship with a correlation coefficient of 0.76. By determining linear relation values with high accuracy, BP can be measured with insignificant error. Therefore it can be suggested as a new method to measure the blood pressure continuously.

The electrocardiogram artifact is a major contamination in the electromyogram signals when electromyogram signal is recorded from upper trunk muscles and because of that the contaminated electromyogram is not useful. Removing electrocardiogram contamination from electromyogram signals. In this paper, the clean electromyogram signal, electrocardiogram artifact and electrocardiogram signal were recorded from leg muscles, the pectoralis major muscle of the left side and V4, respectively. After the pre-processing, contaminated electromyogram signal is simulated with a combination of clean electromyogram and electrocardiogram artifact. Then, contaminated electromyogram is cleaned using adaptive subtraction method. This method contains some steps; (1) QRS detection, (2) formation of electrocardiogram template by averaging the electrocardiogram complexes, (3) using low pass filter to remove undesirable artifacts, (4) subtraction. Performance of our method is evaluated using qualitative criteria, power spectrum density and coherence and quantitative criteria signal to noise ratio, relative error and cross correlation. The result of signal to noise ratio, relative error and cross correlation is equal to 10.493, 0.04 and %97 respectively. Finally, there is a comparison between proposed method and some existing methods. The result indicates that adaptive subtraction method is somewhat effective to remove electrocardiogram artifact from contaminated electromyogram signal and has an acceptable result.