Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947101
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Traditionally, surface plasmon resonance (SPR) biosensors utilize absorption of light radiation incident upon noble metal films above the total internal reflection angles. Herein we extend the SPR phenomenon to incorpora...Traditionally, surface plasmon resonance (SPR) biosensors utilize absorption of light radiation incident upon noble metal films above the total internal reflection angles. Herein we extend the SPR phenomenon to incorporate cavity plasmon resonance (CPR) excitation of metallic films at incidence angles below the critical angle. While SPR occurs for TM polarized light only and requires very specific excitation conditions, which could be disadvantageous in some practical designs, CPR does not require complicated evanescent field excitation above the critical total internal reflection angle and can be implemented for both transverse electric (TE) and transverse magnetic (TM) fields even under normal incidence (TEM). These and other unique features of CPR enable a more flexible design of highly efficient and sensitive biosensing devices.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947100
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This paper represents a novel magnetic nanoparticle measurement method for applications in clinical diagnostics. Planar microcoils and impedance bridge measurement are used to measure the amount of the particles. Macro s...This paper represents a novel magnetic nanoparticle measurement method for applications in clinical diagnostics. Planar microcoils and impedance bridge measurement are used to measure the amount of the particles. Macro size coils made on PCB are used to test and verify the measurement method and measurement electronics. Experimental tests and simulative results will be used for a future microscale sensing system.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947099
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Locating functionally important protein surfaces and identifying the catalytic site residues are critical for studying enzyme functions. Here, we present methods for predicting and characterizing catalytic sites of enzym...Locating functionally important protein surfaces and identifying the catalytic site residues are critical for studying enzyme functions. Here, we present methods for predicting and characterizing catalytic sites of enzymes at atomic level that is fold-independent. By extract atomic patterns of catalytic residues in surface pockets computed geometrically, we develop a library of atomic patterns on protein functional surfaces of ca 700 structures. Together with propensities of secondary structures and residue occurrence in active sites, we develop methods to identify functionally important surfaces on protein structures and to locate key residues. We discuss application of our methods to amylase, dioxygenase, deaminase, dehalogenase, and hydratase. A large scale cross-validated prediction study shows that our method is sensitive and specific.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947098
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The ability to discriminate nucleic acid sequences is necessary for a wide variety of applications: high throughput screening, distinguishing genetically modified organisms (GMOs), molecular computing, differentiating bi...The ability to discriminate nucleic acid sequences is necessary for a wide variety of applications: high throughput screening, distinguishing genetically modified organisms (GMOs), molecular computing, differentiating biological markers, fingerprinting a specific sensor response for complex systems, etc. Hybridization-based target recognition and discrimination is central to the operation of nucleic acid sensor systems. Therefore developing a quantitative correlation between mishybridization events and sensor out put is critical to the accurate interpretation of results. In this work, using experimental data produced by introducing single mutations (single nucleotide polymorphisms, SNPs) in the probe sequence of computational catalytic molecular beacons (deoxyribozyme gates) [1], we investigate coding theory algorithms for uniquely categorizing SNPs based on the calculation of syndromes.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947097
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We prove that the introns play the role of a decoy in absorbing mutations in the same way hollow uninhabited structures are used by the military to protect important installations. Our approach is based on a probability...We prove that the introns play the role of a decoy in absorbing mutations in the same way hollow uninhabited structures are used by the military to protect important installations. Our approach is based on a probability of error analysis, where errors are mutations which occur in the exon sequences. We derive the optimal exon length distribution, which minimizes the probability of error in the genome. Furthermore, to understand how can Nature generate the optimal distribution, we propose a diffusive random walk model for exon generation throughout evolution. This model results in an alpha stable exon length distribution, which is asymptotically equivalent to the optimal distribution. Experimental results show that both distributions accurately fit the real data. Given that introns also drive biological evolution by increasing the rate of unequal crossover between genes, we conclude that the role of introns is to maintain a genius balance between stability and adaptability in eukaryotic genomes.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947096
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Solution of the electroencephalogram (EEG) forward problem in a realistic head model is necessary for accurate source analysis. Realistic head models are usually derived from volumetric magnetic resonance images that pro...Solution of the electroencephalogram (EEG) forward problem in a realistic head model is necessary for accurate source analysis. Realistic head models are usually derived from volumetric magnetic resonance images that provide a voxel resolution of about 1 mm3. The availability of an electrical head model with this resolution would therefore be extremely advantageous. Head models with resolution in the millimeter range that incorporate the anisotropic properties of their elements have been formulated with the finite element method (FEM). However, these FEM models are fraught with complications related to irregular grids and meshes, along with the incumbent segmentation problems. Presented here is a finite volume method (FVM) formulation of the realistic head model in cubic elements that can ameliorate some of these problems, can incorporate tissue anisotropy, and is both physically intuitive and simple to implement.
Long CJ, Purdon RL, Temereanca S
… +3 more, Desai NU, Hämäläinen M, Brown EN
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947095
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Computational solutions to the high-dimensional Kalman filtering problem are described in the setting of the MEG inverse problem. The overall objective of the described work is to localize and estimate dynamic brain acti...Computational solutions to the high-dimensional Kalman filtering problem are described in the setting of the MEG inverse problem. The overall objective of the described work is to localize and estimate dynamic brain activity from observed extraneous magnetic fields recorded at an array of sensor positions on the scalp and to do so in a manner that takes advantage of the true underlying statistical continuity in the current sources. To this end, we outline inverse mapping procedures that combine models of current dipoles with dynamic state-space estimation algorithms. While these algorithms are eminently well-suited to this class of dynamic inverse problems, they possess computational limitations that need to be addressed either by approximation or through the use of high performance computational resources. In this work we describe such a high performance computing (HPC) solution to the Kalman filter and demonstrate its applicability to the magnetoencephalography (MEG) inverse problem.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947094
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We propose a novel approach to image 3- dimensional (3-D) cardiac electrical activity from intra-cavity electrical potentials. The 3-D cardiac electrical activity is estimated by minimizing the difference between the rec...We propose a novel approach to image 3- dimensional (3-D) cardiac electrical activity from intra-cavity electrical potentials. The 3-D cardiac electrical activity is estimated by minimizing the difference between the recorded and model-generated intra-cavity potential distributions. The feasibility of the proposed concept is tested by a computer simulation.
Karunajeewa AS, Abeyratne UR, Rathnayake SI
… +1 more, Swarnkar V
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947093
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Obstructive Sleep Apnea (OSA) is a serious disease caused by the collapse of upper airways during sleep. The present method of measuring the severity of OSA is the Apnea Hypopnea Index (AHI). The AHI is defined as the av...Obstructive Sleep Apnea (OSA) is a serious disease caused by the collapse of upper airways during sleep. The present method of measuring the severity of OSA is the Apnea Hypopnea Index (AHI). The AHI is defined as the average number of Obstructive events (Apnea and Hypopnea, OAH-events) during the total sleep period. The number of occurrence of OAH events during each hour of sleep is a random variable with an unknown probability density function. Thus the measure AHI alone is insufficient to describe its true nature. We propose a new measure Dynamic Apnea Hypopnea Index Time Series (DAHI), which captures the temporal density of Apnea event over shorter time intervals, and use its higher moments to obtain a dynamic characterization of OSA.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947092
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The aim of this study was to capture and analyze the nonlinear characteristics of asthmatic wheezes, reflected in the quadrature phase coupling of their harmonics, as they evolve over time within the breathing cycle. To...The aim of this study was to capture and analyze the nonlinear characteristics of asthmatic wheezes, reflected in the quadrature phase coupling of their harmonics, as they evolve over time within the breathing cycle. To achieve this, the continuous wavelet transform was combined with third-order statistics/spectra. Wheezes from diagnosed asthmatic patients were drawn from a lung sound database and analyzed in the time-bi-frequency domain. The analysis results justified the efficient performance of this combinatory approach to reveal and quantify the evolution of wheeze nonlinearities with time.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947091
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The aim of this study was to reveal and analyze the nonlinear characteristics of heart sounds, reflected in the quadrature phase coupling of the contained frequencies, as they evolve over time. To achieve this, the conti...The aim of this study was to reveal and analyze the nonlinear characteristics of heart sounds, reflected in the quadrature phase coupling of the contained frequencies, as they evolve over time. To achieve this, the continuous wavelet transform was combined with third-order statistics/spectra in order to analyze their non Gaussian character, taking into account their non-stationarity. Heart sounds from patients with several pathologies that exhibit murmurs were drawn from a heart sound database and analyzed in the time-bi-frequency domain. The analysis results justified the efficient performance of this combinatory approach to reveal and quantify the evolution of heart murmurs nonlinearities with time.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947090
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The etiology of skeletal muscle fatigue is not well understood partly because techniques portraying muscle performance in vivo are limited by either their invasiveness (e.g., needle electrodes) or poor spatial resolution...The etiology of skeletal muscle fatigue is not well understood partly because techniques portraying muscle performance in vivo are limited by either their invasiveness (e.g., needle electrodes) or poor spatial resolution (e.g., surface EMG). To better characterize effects of FES and muscle fatigue, we captured real-time high resolution dynamics of the human forearm before and after a fatigue exercise using ultrasound strain imaging. A 10 MHz linear ultrasound probe aligned with the fiber axis of the 3rd flexor digitorum superficialis (FDS) provided scans at 3-msec intervals during isometric twitch and tetanic contractions evoked by low and high frequency electrical stimuli (ES). Ultrasound images synchronized with traditional force and EMG were obtained for 5 healthy adults before and after a fatiguing exercise, induced by sustained maximal exertion of the middle finger pressed against a restraint until the initial force decreased by 75%. Immediately after fatigue, twitch and tetanic stimuli generated 55.1% and 19.5% less force, respectively, implying that low frequency fatigue dominated. The force deficit was associated with a decrease in several mechanical properties of the fatigued muscle during twitch contractions, such as transverse peak strain (34 +/- 15%) and half peak strain duration (32.3 +/- 12.5 msec). Changes were not uniform across the imaged section of the muscle, suggesting that boundary conditions or fiber heterogeneity affected the strain profile. Indeed, high stress zones appeared closer to the muscle-tendon junction during isometric contractions. This study provided new insight on the elastic behavior of muscle and potential mechanisms of injury, especially directed at prolonged stimulation and control of a neuromuscular prosthesis.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947089
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We have developed a hybrid neuromechanical joint to investigate the nonlinear properties of muscle in a physiologically relevant context. We constructed the hybrid system by connecting a live frog gastrocnemius muscle to...We have developed a hybrid neuromechanical joint to investigate the nonlinear properties of muscle in a physiologically relevant context. We constructed the hybrid system by connecting a live frog gastrocnemius muscle to a joint which is simulated as an inverted pendulum. We first tested this hybrid system with a spring as the actuator to ensure that the perturbation-response trajectories using living muscle would accurately describe the mechanical properties of the muscle. This hybrid neuromechanical system, with muscle as the actuator, responded to impulse torque perturbations with stable damped oscillations. Joint settling times to perturbations were measured while the joint mass and the initial muscle length were varied. Passive muscle alone stabilized small perturbations. With heavier joint masses and shorter initial muscle lengths the system became increasingly unstable. We found that the hybrid neuromechanical joint is an accurate tool to study the neuromuscular system.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947088
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The problem of automatically locating the fovea, a spot located in the center of the macula and responsible for sharp central vision, on the retinal surface image is considered. The uniqueness of the strategy presented h...The problem of automatically locating the fovea, a spot located in the center of the macula and responsible for sharp central vision, on the retinal surface image is considered. The uniqueness of the strategy presented here is the relatively small amount of computational expense of a quick and robust method conducive to real-time applications. The algorithm first identifies the main blood vessels using the modified active shape model (ASM) and then expeditiously attempts to fit the parabolic shape to the overall result to locate the fovea. A reliable tracking strategy is also proposed here to estimate the required vertex when the prior information of the optic disk is not available. When a patient's retinal vessel data have been modeled a priori and used as template, the technique brought up here should find its advantage in real-time image-guided applications like a computer-assisted photocoagulation treatment.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947087
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The automatic detection of the position of the optic disc is an important step in the automatic analysis of retinal images. A method to detect the approximate position of the optic disc using kNN regression is presented....The automatic detection of the position of the optic disc is an important step in the automatic analysis of retinal images. A method to detect the approximate position of the optic disc using kNN regression is presented. The method starts by building a regression model of the optic disc position. Using a prior vessel segmentation all vessel pixels are searched for those which are inside the optic disc according to the regression model. The regression output is blurred to handle noise. The point which is closest to the middle of the optic disc is chosen. The method was tested on 1000 screening images and was able to find the correct position in 99.9% of all cases.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947086
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Traditional stand-alone computer-assisted surgery (CAS) systems impede the ubiquitous and simultaneous access by multiple users. With advances in computing and networking technologies, ubiquitous access to CAS systems be...Traditional stand-alone computer-assisted surgery (CAS) systems impede the ubiquitous and simultaneous access by multiple users. With advances in computing and networking technologies, ubiquitous access to CAS systems becomes possible and promising. Based on our preliminary work, CASMIL, a stand-alone CAS server developed at Wayne State University, we propose a novel mobile CAS system, UbiCAS, which allows surgeons to retrieve, review and interpret multimodal medical images, and to perform some critical neurosurgical procedures on heterogeneous devices from anywhere at anytime. Furthermore, various optimization techniques, including caching, prefetching, pseudo-streaming-model, and compression, are used to guarantee the QoS of the UbiCAS system. UbiCAS enables doctors at remote locations to actively participate remote surgeries, share patient information in real time before, during, and after the surgery.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947085
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The feasibility of using 2D real-time control to navigate ferromagnetic entities in an MRI bore for novel medical interventions is assessed. Preliminary experimental results confirm that a simple PID controller can be su...The feasibility of using 2D real-time control to navigate ferromagnetic entities in an MRI bore for novel medical interventions is assessed. Preliminary experimental results confirm that a simple PID controller can be suitable for several applications where targeting out-of-reach locations within the cardiovascular system is essential.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947084
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An approach for the robust feedback control of a class of biomedical systems in chained form is presented. The control approach is based on modeling error compensation techniques and a recursive cascade scheme. Numerical...An approach for the robust feedback control of a class of biomedical systems in chained form is presented. The control approach is based on modeling error compensation techniques and a recursive cascade scheme. Numerical simulations on three biomedical models of VIH-1, cancer and glucose systems are provided to illustrate our findings.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947083
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Progressive preictal dynamical convergence and postictal divergence of dynamical EEG descriptors among brain regions has been reported in human temporal lobe epilepsy (TLE) and in a rodent model of TLE. There are also re...Progressive preictal dynamical convergence and postictal divergence of dynamical EEG descriptors among brain regions has been reported in human temporal lobe epilepsy (TLE) and in a rodent model of TLE. There are also reports of anticonvulsant effects of high frequency stimulation of the hippocampus in humans. We postulate that this anticonvulsant effect is due to dynamical resetting by the electrical stimulation. The following study investigated the effects of acute hippocampal electrical stimulation on dynamical transitions in the brain of a spontaneously seizing animal model of TLE to test the hypothesis of divergence in dynamical values by electrical stimulation of the hippocampus.
Kinoshita H, Yoshizawa M, Inagaki M
… +3 more, Uemura K, Sugimachi M, Sunagawa K
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17947082
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In this study, we have introduced the pattern classifier using the self-organizing map (SOM) for detecting fatal cardiac arrhythmia in implantable cardioverter-defibrillators (ICDs). The SOM has learned patterns of sinus...In this study, we have introduced the pattern classifier using the self-organizing map (SOM) for detecting fatal cardiac arrhythmia in implantable cardioverter-defibrillators (ICDs). The SOM has learned patterns of sinus rhythm, ventricular fibrillation and ventricular tachycardia with the feature vectors extracted from electrocardiogram and right ventricular volume measured during an arrhythmia induction experiment of a dog. After learning, neurons of the SOM were labeled by using the k-Nearest Neighbor method. It was shown that the accuracy of the proposed method was higher than other competitive methods applied to the same test data.