Search for: sensitivity-and-specificity
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    Finger photoplethysmogram pulse amplitude changes induced by flow-mediated dilation

    , Article Physiological Measurement ; Volume 29, Issue 5 , 2008 , Pages 625-637 ; 09673334 (ISSN) Zahedi, E ; Jaafar, R ; Mohd Ali, M. A ; Mohamed, A. L ; Maskon, O ; Sharif University of Technology
    This study was conducted to investigate the utility and efficacy of finger photoplethysmogram pulse amplitude (PPG-AC) in comparison with the standard Doppler ultrasound in assessing an endothelial function via flow-mediated dilation (FMD). High-resolution B-mode scanning of the right brachial artery (BA) of 31 healthy subjects aged 39.7 ± 11.3 (range 22-64) years and 52 risk subjects aged 47.7 ± 10.8 (range 30-65) years were performed before and after 4 min of upper arm occlusion. Concurrent with the ultrasound measurement (where color Doppler imaging was used to enhance arterial boundary detection), PPG signals were recorded from both index fingers for cross evaluation and comparison. Our... 

    Sensitivity analysis of the OWA operator

    , Article IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics ; Volume 38, Issue 2 , 2008 , Pages 547-552 ; 10834419 (ISSN) Zarghami, M ; Szidarovszky, F ; Ardakanian, R ; Sharif University of Technology
    The successful design and application of the ordered weighted averaging (OWA) method as a decision-making tool depend on the efficient computation of its order weights. The most popular methods for determining the order weights are the fuzzy linguistic quantifiers approach and the minimal variability method, which give different behavior patterns for the OWA. These two methods will be first analyzed in detail by using sensitivity analysis on the outputs of the OWA with respect to the optimism degree of the decision maker, and then the two methods will be compared. The fuzzy linguistic quantifiers approach gives more information about the behavior of the OWA outputs in comparison to the... 

    QSAR study of heparanase inhibitors activity using artificial neural networks and Levenberg-Marquardt algorithm

    , Article European Journal of Medicinal Chemistry ; Volume 43, Issue 3 , 2008 , Pages 548-556 ; 02235234 (ISSN) Jalali Heravi, M ; Asadollahi Baboli, M ; Shahbazikhah, P ; Sharif University of Technology
    A linear and non-linear quantitative structure-activity relationship (QSAR) study is presented for modeling and predicting heparanase inhibitors' activity. A data set that consisted of 92 derivatives of 2,3-dihydro-1,3-dioxo-1H-isoindole-5-carboxylic acid, furanyl-1,3-thiazol-2-yl and benzoxazol-5-yl acetic acids is used in this study. Among a large number of descriptors, four parameters classified as physico-chemical, topological and electronic indices are chosen using stepwise multiple regression technique. The artificial neural networks (ANNs) model shows superiority over the multiple linear regressions (MLR) by accounting 87.9% of the variances of antiviral potency of the heparanase... 

    Classification of vascular function in upper limb using bilateral photoplethysmographic signals

    , Article Physiological Measurement ; Volume 29, Issue 3 , 2008 , Pages 365-374 ; 09673334 (ISSN) Hesam Shariati, N ; Zahedi, E ; Jajai, H. M ; Sharif University of Technology
    Bilateral PPG signals have been used for comparative study of two groups of healthy (free from any cardiovascular risk factors) and diabetic (as cardiovascular disease risk group) subjects in the age-matched range 40-50 years. The peripheral blood pulsations were recorded simultaneously from right and left index fingers for 90 s. Pulses have been modeled with the ARX440 model in the interval of 300 sample points with 100 sample points overlap between segments. Model parameters of three segments based on the highest fitness (higher than 80%) of modeled segments were retained for each subject. Subsequently, principal component analysis (PCA) was applied to the parameters of retained segments... 

    Images of finite sized spherical particles in confocal and conventional microscopes when illuminated with arbitrary polarization

    , Article Applied Optics ; Volume 47, Issue 3 , 2008 , Pages 453-458 ; 1559128X (ISSN) Alali, S ; Massoumian, F ; Sharif University of Technology
    OSA - The Optical Society  2008
    We investigate the form of the image of a finite sized spherical particle in confocal and conventional microscopes when the illuminating light has an arbitrary polarization. In particular, we take the cases of radial and azimuthal polarizations and use the Mie theory to find the scattered field from differently sized particles for these cases. We present numerical results for the changes in the detected intensity when subresolution and resolvable spherical particles are illuminated with particular wavelengths and polarizations. Further, we find the limiting size of a particle for which it can be considered a point scatterer for a particular wavelength. © 2008 Optical Society of America  

    Model-based fiducial points extraction for baseline wandered electrocardiograms

    , Article IEEE Transactions on Biomedical Engineering ; Volume 55, Issue 1 , 2008 , Pages 347-351 ; 00189294 (ISSN) Sayadi, O ; Shamsollahi, M. B ; Sharif University of Technology
    A fast algorithm based on the nonlinear dynamical model for the electrocardiogram (ECG) is presented for the precise extraction of the characteristic points of these signals with baseline drift. Using the adaptive bionic wavelet transform, the baseline wander is removed efficiently. In fact by the means of the bionic wavelet transform, the resolution in the time-frequency domain can be adaptively adjusted not only by the signal frequency but also by the signal instantaneous amplitude and its first-order differential, which results in a better baseline wander cancellation. At the next step the parameters of the model are chosen to have the least square error with the original ECG. Determining... 

    A nonlinear Bayesian filtering framework for ECG denoising

    , Article IEEE Transactions on Biomedical Engineering ; Volume 54, Issue 12 , November , 2007 , Pages 2172-2185 ; 00189294 (ISSN) Sameni, R ; Shamsollahi, M. B ; Jutten, C ; Clifford, G. D ; Sharif University of Technology
    In this paper, a nonlinear Bayesian filtering framework is proposed for the filtering of single channel noisy electrocardiogram (ECG) recordings. The necessary dynamic models of the ECG are based on a modified nonlinear dynamic model, previously suggested for the generation of a highly realistic synthetic ECG. A modified version of this model is used in several Bayesian filters, including the Extended Kalman Filter, Extended Kalman Smoother, and Unscented Kalman Filter. An automatic parameter selection method is also introduced, to facilitate the adaptation of the model parameters to a vast variety of ECGs. This approach is evaluated on several normal ECGs, by artificially adding white and... 

    Determination of fentanyl in human plasma by head-space solid-phase microextraction and gas chromatography-mass spectrometry

    , Article Journal of Pharmaceutical and Biomedical Analysis ; Volume 43, Issue 5 , 2007 , Pages 1763-1768 ; 07317085 (ISSN) Bagheri, H ; Es-haghi, A ; Khalilian, F ; Rouini, M. R ; Sharif University of Technology
    A head-space solid-phase microextraction (HS-SPME) method coupled to GC-MS was developed to extract fentanyl from human plasma. The protein binding was reduced by acidification and, eventually, the sample was deproteinized with trichloroacetic acid. The parameters influencing adsorption (extraction time, temperature, pH and salt addition) and desorption (desorption time and temperature) of the analyte on the fibre were investigated and validated for method development. The developed method proved to be rapid, simple, easy and inexpensive and offers high sensitivity and reproducibility. Linear range was obtained from 0.1 ng/ml to 2 μg/ml. The limit of detection was 0.03 ng/ml while an... 

    Headspace solvent microextraction as a simple and highly sensitive sample pretreatment technique for ultra trace determination of geosmin in aquatic media

    , Article Journal of Separation Science ; Volume 29, Issue 1 , 2006 , Pages 57-65 ; 16159306 (ISSN) Bagheri, H ; Salemi, A ; Sharif University of Technology
    A headspace solvent microextraction method was developed for the trace determination of geosmin, an odorant compound, in water samples. After performing the extraction by a microdrop of an organic solvent, the microdrop was introduced directly into a GC-MS injection port. One-at-the-time optimization strategy was applied to investigate and optimize some important extraction parameters such as type of solvent, drop volume, temperature, stirring rate, ionic strength, sample volume, and extraction time. The analytical data exhibited an RSD of less than 5% (n = 5), a linear calibration range of 5-900 ng/L (r2 > 0.998), and a detection limit of 0.8 and 3.3 ng/L using two different sets of... 

    Altered expression of STAT genes in periodontitis

    , Article Human Antibodies ; Volume 29, Issue 3 , 2021 , Pages 209-216 ; 10932607 (ISSN) Gholami, L ; Movafagh, A ; Badrlou, E ; Nazer, N ; Yari, M ; Sadeghi, G ; Mirzajani, S ; Shadnoush, M ; Sayad, A ; Ghafouri Fard, S ; Sharif University of Technology
    IOS Press BV  2021
    Signal Transducer and Activator of Transcription (STAT) pathway is functionally located downstream of Janus kinases proteins and can integrate signals from diverse pathways, thus regulating several aspects of immune responses. Although contribution of STAT proteins in the pathogenesis of several inflammatory conditions has been confirmed, their role in the development of periodontitis has been less appraised. Thus, we assessed levels of STAT transcripts in the periodontal tissues and circulation of affected individuals compared with the corresponding controls. Expression of STAT1 was remarkably lower in tissues samples of patients compared with control tissues (Ratio of mean expression (RME)... 

    Using distance on the Riemannian manifold to compare representations in brain and in models

    , Article NeuroImage ; Volume 239 , 2021 ; 10538119 (ISSN) Shahbazi, M ; Shirali, A ; Aghajan, H ; Nili, H ; Sharif University of Technology
    Academic Press Inc  2021
    Representational similarity analysis (RSA) summarizes activity patterns for a set of experimental conditions into a matrix composed of pairwise comparisons between activity patterns. Two examples of such matrices are the condition-by-condition inner product and correlation matrix. These representational matrices reside on the manifold of positive semidefinite matrices, called the Riemannian manifold. We hypothesize that representational similarities would be more accurately quantified by considering the underlying manifold of the representational matrices. Thus, we introduce the distance on the Riemannian manifold as a metric for comparing representations. Analyzing simulated and real fMRI... 

    External parameter orthogonalization-support vector machine for processing of attenuated total reflectance-mid-infrared spectra: A solution for saffron authenticity problem

    , Article Analytica Chimica Acta ; Volume 1154 , 2021 ; 00032670 (ISSN) Amirvaresi, A ; Parastar, H ; Sharif University of Technology
    Elsevier B.V  2021
    In the present work, a new approach based on external parameter orthogonalization combined with support vector machine (EPO-SVM) is proposed for processing of attenuated total reflectance-Fourier transform mid-infrared (ATR-FT-MIR) spectra with the goal of solving authentication problem in saffron, the most expensive spice in the world. First, one-hundred authentic saffron samples are clustered by principal component analysis (PCA) with EPO as the best preprocessing strategy. Then, EPO-SVM is used for the detection of four commonly used plant-derived adulterants (i.e. safflower, calendula, rubia, and style) in binary mixtures (saffron and each of plant adulterants) and its performance is... 

    Noninvasive estimation of tissue temperature via high-resolution spectral analysis techniques

    , Article IEEE Transactions on Biomedical Engineering ; Volume 52, Issue 2 , 2005 , Pages 221-228 ; 00189294 (ISSN) Nasiri Amini, A ; Ebbini, E. S ; Georgiou, T. T ; Sharif University of Technology
    We address the noninvasive temperature estimation from pulse-echo radio frequency signals from standard diagnostic ultrasound imaging equipment. In particular, we investigate the use of a high-resolution spectral estimation method for tracking frequency shifts at two or more harmonic frequencies associated with temperature change. The new approach, employing generalized second-order statistics, is shown to produce superior frequency shift estimates when compared to conventional high-resolution spectral estimation methods Seip and Ebbini (1995). Furthermore, temperature estimates from the new algorithm are compared with results from the more commonly used echo shift method described in Simon... 

    A metabonomics study on crohn's disease using nuclear magnetic resonance spectroscopy

    , Article HealthMED ; Volume 6, Issue 11 , July , 2012 , Pages 3577-3583 ; 18402291 (ISSN) Fathi, F ; Kyani, A ; Nejad, M. R ; Rezaye Tavirani, M ; Naderi, N ; Zali, M. R ; Tafazzoli, M ; Oskouie, A. A ; Sharif University of Technology
    Objective: Crohn's disease (CD) is one the important illnesses can affect any part of the gastrointestinal tract. CD is not easily diagnosed using the clinical tests. Thus, the discovery of proper methods would be a major step towards CD diagnosis. The aim of this study was to seek the metabolic biomarkers causes of CD compare to control group. Materials and Methods: In present study, we employed metabolic profiling using proton nuclear magnetic resonance spectroscopy (1HNMR) to find metabolites in serum which are helpful for the diagnosis of CD. Classification of CD and healthy subject was done using classification and regression trees (CART). The metabolites that caused changes in people... 

    Antepartum fetal heart rate feature extraction and classification using empirical mode decomposition and support vector machine

    , Article BioMedical Engineering Online ; Volume 10 , 2011 ; 1475925X (ISSN) Krupa, N ; MA, M. A ; Zahedi, E ; Ahmed, S ; Hassan, F. M ; Sharif University of Technology
    Background: Cardiotocography (CTG) is the most widely used tool for fetal surveillance. The visual analysis of fetal heart rate (FHR) traces largely depends on the expertise and experience of the clinician involved. Several approaches have been proposed for the effective interpretation of FHR. In this paper, a new approach for FHR feature extraction based on empirical mode decomposition (EMD) is proposed, which was used along with support vector machine (SVM) for the classification of FHR recordings as 'normal' or 'at risk'.Methods: The FHR were recorded from 15 subjects at a sampling rate of 4 Hz and a dataset consisting of 90 randomly selected records of 20 minutes duration was formed from... 

    Discrimination between different degrees of coronary artery disease using time-domain features of the finger photoplethysmogram in response to reactive hyperemia

    , Article Biomedical Signal Processing and Control ; Volume 18 , 2015 , Pages 282-292 ; 17468094 (ISSN) Hosseini, Z. S ; Zahedi, E ; Movahedian Attar, H ; Fakhrzadeh, H ; Parsafar, M. H ; Sharif University of Technology
    Elsevier Ltd  2015
    Atherosclerosis is a major cause of coronary artery disease leading to morbidity and mortality worldwide. Currently, coronary angiography is considered to be the most accurate technique to diagnose coronary artery disease (CAD). However, this technique is an invasive and expensive procedure with risks of serious complications. Since the symptoms of CAD are not noticed until advanced stages of the disease, early and effective diagnosis of CAD is considered a pertinent measure. In this paper, a non-invasive optical signal, the finger photoplethysmogram (PPG) obtained before and after reactive hyperemia is investigated to discriminate between subjects with different CAD conditions. To this end,... 

    Simultaneous determination of epinephrine and acetaminophen concentrations using a novel carbon paste electrode prepared with 2,2′-[1,2 butanediylbis(nitriloethylidyne)]-bis-hydroquinone and TiO2 nanoparticles

    , Article Colloids and Surfaces B: Biointerfaces ; Volume 76, Issue 1 , 2010 , Pages 82-87 ; 09277765 (ISSN) Mazloum Ardakani, M ; Beitollahi, H ; Sheikh Mohseni, M. A ; Benvidi, A ; Naeimi, H ; Nejati Barzoki, M ; Taghavinia, N ; Sharif University of Technology
    A carbon paste electrode (CPE) modified with 2,2′-[1,2 butanediylbis(nitriloethylidyne)]-bis-hydroquinone (BBNBH) and TiO2 nanoparticles was used for the sensitive voltammetric determination of epinephrine (EP). The electrochemical response characteristics of the modified electrode toward EP and acetaminophen (AC) were investigated by cyclic and differential pulse voltammetry (CV and DPV). The results showed an efficient catalytic activity of the electrode for the electrooxidation of EP, which leads to a reduction in its overpotential by more than 270 mV. The effects of pH and potential sweep rate on the mechanism of the electrode process were investigated. The modified electrode exhibits an... 

    Electrospun magnetic polybutylene terephthalate nanofibers for thin film microextraction

    , Article Journal of Separation Science ; Volume 40, Issue 19 , 2017 , Pages 3857-3865 ; 16159306 (ISSN) Bagheri, H ; Najafi Mobara, M ; Roostaie, A ; Baktash, M. Y ; Sharif University of Technology
    A thin film microextraction method using elecrospun magnetic polybutylene terephthalate nanofibers is developed and implemented to isolate some selected triazines. Due to the high mechanical stability of these nanofibers, they are repeatedly used under harsh magnetic stirring and ultrasonic conditions without any damage and structure degradation. The presence of magnetic nanoparticles within the nanofiber structure increases the extraction efficiency while the fibers could be collected by an external magnet. The synthesized nanocomposite showed strong affinity toward the selected analytes. Apart from the concentration of magnetic nanoparticles within the nanocomposite network, the effect of... 

    A novel approach to spinal 3-D kinematic assessment using inertial sensors: towards effective quantitative evaluation of low back pain in clinical settings

    , Article Computers in Biology and Medicine ; Volume 89 , 2017 , Pages 144-149 ; 00104825 (ISSN) Ashouri, S ; Abedi, M ; Abdollahi, M ; Dehghan Manshadi, F ; Parnianpour, M ; Khalaf, K ; Sharif University of Technology
    This paper presents a novel approach for evaluating LBP in various settings. The proposed system uses cost-effective inertial sensors, in conjunction with pattern recognition techniques, for identifying sensitive classifiers towards discriminate identification of LB patients. 24 healthy individuals and 28 low back pain patients performed trunk motion tasks in five different directions for validation. Four combinations of these motions were selected based on literature, and the corresponding kinematic data was collected. Upon filtering (4th order, low pass Butterworth filter) and normalizing the data, Principal Component Analysis was used for feature extraction, while Support Vector Machine... 

    Alzheimer’s disease early diagnosis using manifold-based semi-supervised learning

    , Article Brain Sciences ; Volume 7, Issue 8 , 2017 ; 20763425 (ISSN) Khajehnejad, M ; Habibollahi Saatlou, F ; Mohammadzade, H ; Sharif University of Technology
    Alzheimer’s disease (AD) is currently ranked as the sixth leading cause of death in the United States and recent estimates indicate that the disorder may rank third, just behind heart disease and cancer, as a cause of death for older people. Clearly, predicting this disease in the early stages and preventing it from progressing is of great importance. The diagnosis of Alzheimer’s disease (AD) requires a variety of medical tests, which leads to huge amounts of multivariate heterogeneous data. It can be difficult and exhausting to manually compare, visualize, and analyze this data due to the heterogeneous nature of medical tests, therefore, an efficient approach for accurate prediction of the...