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This page shows you the most recent publications within this specialty of the MedWorm directory. This is page number 13.

Arterial Pressure and Flow Wave Analysis Using Time-Domain 1-D Hemodynamics.
Abstract We reviewed existing methods for analyzing, in the time domain, physical mechanisms underlying the patterns of blood pressure and flow waveforms in the arterial system. These are wave intensity analysis and separations into several types of waveforms: (i) forward- and backward-traveling, (ii) peripheral and conduit, or (iii) reservoir and excess. We assessed the physical information provided by each method and showed how to combine existing methods in order to quantify contributions to numerically generated waveforms from previous cardiac cycles and from specific regions and properties of the numerical dom...
Source: Annals of Biomedical Engineering - August 20, 2014 Category: Biomedical Engineering Authors: Willemet M, Alastruey J Tags: Ann Biomed Eng Source Type: research

Development of a closed-loop J–T cryoablation device with a long cooling area and multiple expansion parts
Cryoablation is a surgical procedure used to freeze defective cells by inserting a low temperature probe into a human body to destroy malignant tissues. Miniaturized Joule–Thomson (J–T) refrigerators are often used to minimize the volume of the cooling device and reduce the destruction zone of normal tissue. The cooling effects of the existing probes are not uniformly generated along the longitudinal direction of the probe, which makes their applications less effective in surgeries of incompetent great saphenous veins (GSVs), where the target cells are distributed over a broad range. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - August 20, 2014 Category: Biomedical Engineering Authors: Cheonkyu Lee, Seungwhan Baek, Jisung Lee, Gyuwan Hwang, Sangkwon Jeong, Sang Woo Park Source Type: research

Measurement of compliance of infusion device consumable elements using an analytical weighing balance
The time of onset of occlusion of syringe drivers has been demonstrated to be influenced by the compliance of the connected circuit, where systems with high compliance which deform significantly with applied pressure will generally have increased times of occlusion [1–5]. This could potentially increase the time during which drugs are not being administered to the patient and where lines with increasing compliance will contribute to an increase of bolus volume at the release of the occlusion pressure. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - August 20, 2014 Category: Biomedical Engineering Authors: Douglas McG. Clarkson, Romain Barbosa Tags: Technical note Source Type: research

Hierarchical Interference Mitigation for Massive MIMO Cellular Networks
We propose a hierarchical interference mitigation scheme for massive MIMO cellular networks. The MIMO precoder at each base station (BS) is partitioned into an inner precoder and an outer precoder. The inner precoder controls the intra-cell interference and is adaptive to local channel state information (CSI) at each BS (CSIT). The outer precoder controls the inter-cell interference and is adaptive to channel statistics. Such hierarchical precoding structure reduces the number of pilot symbols required for CSI estimation in massive MIMO downlink and is robust to the backhaul latency. We study joint optimization of the oute...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

Multi-Stage Robust Chinese Remainder Theorem
It is well-known that the traditional Chinese remainder theorem (CRT) is not robust in the sense that a small error in a remainder may cause a large reconstruction error. A robust CRT was recently proposed for a special case when the greatest common divisor (gcd) of all the moduli is more than 1 and the remaining integers factorized by the gcd are co-prime. It basically says that the reconstruction error is upper bounded by the remainder error level $tau$ if $tau$ is smaller than a quarter of the gcd of all the moduli. In this paper, we consider the robust reconstruction problem for a general set of moduli. We first presen...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

A Barycentric Coordinate Based Distributed Localization Algorithm for Sensor Networks
This paper studies the problem of determining the sensor locations in a large sensor network using only relative distance (range) measurements. Based on a generalized barycentric coordinate representation, our work generalizes the DILOC algorithm to the localization problem under arbitrary deployments of sensor nodes and anchor nodes. First, a criterion and algorithm are developed to determine a generalized barycentric coordinate of a node with respect to its neighboring nodes, which do not require the node to be inside the convex hull of its neighbors. Next, for the localization problem based on the generalized barycentri...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

IRCI Free Range Reconstruction for SAR Imaging With Arbitrary Length OFDM Pulse
Our previously proposed OFDM with sufficient cyclic prefix (CP) synthetic aperture radar (SAR) imaging algorithm is inter-range-cell interference (IRCI) free and achieves ideally zero range sidelobes for range reconstruction. In this OFDM SAR imaging algorithm, the minimum required CP length is almost equal to the number of range cells in a swath, while the number of subcarriers of an OFDM signal needs to be more than the CP length. This makes the length of a transmitted OFDM sequence at least almost twice of the number of range cells in a swath and for a wide swath imaging, the transmitted OFDM pulse length becomes long, ...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

Block-Wise QR-Decomposition for the Layered and Hybrid Alamouti STBC MIMO Systems: Algorithms and Hardware Architectures
Unlike the channel matrix in the spatial division multiplexing (SDM) multiple-input multiple-output (MIMO) communication system, the equivalent channel matrix in the layered Alamouti space-time block coding (STBC) MIMO system comprised 2-by-2 Alamouti sub-blocks. One novel property, found by Sayed about the QR-decomposition (QRD) of this equivalent channel matrix is that the produced ${rm Q}$- and ${rm R}$-matrices are also matrices with Alamouti sub-blocks. Taking advantage of this property, we propose a new block-wise complex Givens rotation (BCGR) based algorithm and a triangular systolic array (TSA) to compute the QRD ...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

A Variational Bayes Framework for Sparse Adaptive Estimation
Recently, a number of mostly $ell_1$ -norm regularized least-squares-type deterministic algorithms have been proposed to address the problem of sparse adaptive signal estimation and system identification. From a Bayesian perspective, this task is equivalent to maximum a posteriori probability estimation under a sparsity promoting heavy-tailed prior for the parameters of interest. Following a different approach, this paper develops a unifying framework of sparse variational Bayes algorithms that employ heavy-tailed priors in conjugate hierarchical form to facilitate posterior inference. The resulting fully automated variati...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

Construction of Doppler Resilient Complete Complementary Code in MIMO Radar
Orthogonal waveform design has become an important research topic in recent years due to the performance advantages of MIMO radar incorporating orthogonal transmitted signals. Complete complementary code (CCC) has ideal ambiguity along the zero Doppler axis, which is desirable in MIMO radar. However, the main obstacle for the extensive usage of CCC is its sensitivity to nonzero Doppler shift. In this paper, we introduce a systematic method of constructing Doppler resilient CCC in MIMO radar, where the range sidelobes can vanish at modest Doppler shifts. In the construction of Doppler resilient waveforms, the generalized Pr...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

Knowledge-Aided Parametric Adaptive Matched Filter With Automatic Combining for Covariance Estimation
In this paper, a knowledge-aided parametric adaptive matched filter (KA-PAMF) is proposed that utilizing both observations (including the test and training signals) and a priori knowledge of the spatial covariance matrix. Unlike existing KA-PAMF methods, the proposed KA-PAMF is able to automatically adjust the combining weight of a priori covariance matrix, thus gaining enhanced robustness against uncertainty in the prior knowledge. Meanwhile, the proposed KA-PAMF is significantly more efficient than its KA nonparametric counterparts when the amount of training signals is limited. One distinct feature of the proposed KA-PA...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

Elliptic Localization: Performance Study and Optimum Receiver Placement
Range based localization often relies on TOA that creates a circular contour or TDOA that yields hyperbolic surface to determine the position of an emitting object. Another approach that has gained attention recently is elliptic localization. Elliptic localization uses an active transmitter to send out a signal and several receivers to acquire the reflected or relayed signal from an object to obtain its location. This paper performs a fundamental investigation on the performance of elliptic localization, for both the synchronous and asynchronous cases between the transmitter and the receivers. Their performance is also cha...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

An Empirical-Bayes Approach to Recovering Linearly Constrained Non-Negative Sparse Signals
We propose two novel approaches for the recovery of an (approximately) sparse signal from noisy linear measurements in the case that the signal is a priori known to be non-negative and obey given linear equality constraints, such as a simplex signal. This problem arises in, e.g., hyperspectral imaging, portfolio optimization, density estimation, and certain cases of compressive imaging. Our first approach solves a linearly constrained non-negative version of LASSO using the max-sum version of the generalized approximate message passing (GAMP) algorithm, where we consider both quadratic and absolute loss, and where we propo...
Source: IEEE Transactions on Signal Processing - August 19, 2014 Category: Biomedical Engineering Source Type: research

IEEE Transactions on Industrial Electronics publication information
(Source: IEEE Transactions on Biomedical Engineering)
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

IEEE Transactions on Biomedical Engineering information for authors
(Source: IEEE Transactions on Biomedical Engineering)
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Coherent Photoacoustic-Ultrasound Correlation and Imaging
Both photoacoustics and ultrasound have been researched extensively but separately. In this letter, we report an initial study on the coherent correlation between pulsed photoacoustic wave and pulse-echo ultrasound wave. By illuminating an object with a pulsed laser and external ultrasound sequentially, both the endogenous photoacoustic wave and pulse-echo ultrasound wave are received and coherently correlated, demonstrating enhanced signal-to-noise ratio. Image contrast of the proposed coherent photoacoustic-ultrasound imaging is also demonstrated to be improved significantly on vessel-mimicking phantom, due to fusion of ...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Effects of Tracer Arrival Time on the Accuracy of High-Resolution (Voxel-Wise) Myocardial Perfusion Maps from Contrast-Enhanced First-Pass Perfusion Magnetic Resonance
First-pass perfusion cardiac magnetic resonance (CMR) allows the quantitative assessment of myocardial blood flow (MBF). However, flow estimates are sensitive to the delay between the arterial and myocardial tissue tracer arrival time (tOnset) and the accurate estimation of MBF relies on the precise identification of tOnset. The aim of this study is to assess the sensitivity of the quantification process to tOnset at voxel level. Perfusion data were obtained from series of simulated data, a hardware perfusion phantom, and patients. Fermi deconvolution has been used for analysis. A novel algorithm, based on sequential decon...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Multisurgeon, Multisite Validation of a Trajectory Planning Algorithm for Deep Brain Stimulation Procedures
This study suggests, albeit on a limited number of surgeons, that the same system can be used to provide assistance across multiple sites and surgeons. (Source: IEEE Transactions on Biomedical Engineering)
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Comparison of Cephalic and Extracephalic Montages for Transcranial Direct Current Stimulation—A Numerical Study
While studies have shown that the application of transcranial direct current stimulation (tDCS) has been beneficial in the stimulation of cortical activity and treatment of neurological disorders in humans, open questions remain regarding the placement of electrodes for optimal targeting of currents for a given functional area. Given the difficulty of obtaining in vivo measurements of current density, modeling of conventional and alternative electrode montages via the finite element method has been utilized to provide insight into tDCS montage performance. It has been shown that extracephalic montages might create larger t...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Characterization of Radiofrequency Ablation Lesion Development Based on Simulated and Measured Intracardiac Electrograms
Radiofrequency ablation (RFA) therapy is the gold standard in interventional treatment of many cardiac arrhythmias. A major obstacle is nontransmural lesions, leading to recurrence of arrhythmias. Recent clinical studies have suggested intracardiac electrogram (EGM) criteria as a promising marker to evaluate lesion development. Seeking for a deeper understanding of underlying mechanisms, we established a simulation approach for acute RFA lesions. Ablation lesions were modeled by a passive necrotic core surrounded by a borderzone with properties of heated myocardium. Herein, conduction velocity and electrophysiological prop...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Surgical Robot for Single-Incision Laparoscopic Surgery
This paper introduces a novel surgical robot for single-incision laparoscopic surgeries. The robot system includes the cone-type remote center-of-motion (RCM) mechanism and two articulated instruments having a flexible linkage-driven elbow. The RCM mechanism, which has two revolute joints and one prismatic joint, is designed to maintain a stationary point at the apex of the cone shape. By placing the stationary point on the incision area, the mechanism allows a surgical instrument to explore the abdominal area through a small incision point. The instruments have six articulated joints, including an elbow pitch joint, which...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Improved Subspace Estimation for Low-Rank Model-Based Accelerated Cardiac Imaging
Sparse sampling methods have emerged as effective tools to accelerate cardiac magnetic resonance imaging (MRI). Low-rank model-based cardiac imaging uses a predetermined temporal subspace for image reconstruction from highly undersampled $({bf k},{hbox{t}})$-space data and has been demonstrated effective for high-speed cardiac MRI. The accuracy of the temporal subspace is a key factor in these methods, yet little work has been published on data acquisition strategies to improve subspace estimation. This paper investigates the use of non-Cartesian ${bf k}$-space trajectories to replace the Cartesian trajectories that are om...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Pulsatile Flow Characterization in a Vessel Phantom With Elastic Wall Using Ultrasonic Particle Image Velocimetry Technique: The Impact of Vessel Stiffness on Flow Dynamics
This study aims to experimentally investigate the impact of vessel stiffness on the flow dynamics of pulsatile vascular flow. Vessel phantoms with elastic walls were fabricated using polyvinyl alcohol cryogel to result in stiffness ranging from 60.9 to 310.3 kPa and tested with pulsatile flows using a flow circulation set-up. Two-dimensional instantaneous and time-dependent flow velocity and shear rate vector fields were measured using ultrasonic particle image velocimetry (EchoPIV). The waveforms of peak velocities measured by EchoPIV were compared with the ultrasonic pulse Doppler spectrum, and the measuring accuracy was...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Quantitative Gait Measurement With Pulse-Doppler Radar for Passive In-Home Gait Assessment
In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step ...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Quantifying Spatiotemporal Properties of Vocal Fold Dynamics Based on a Multiscale Analysis of Phonovibrograms
In this study, an automated wavelet-based analysis of laryngeal high-speed videos based on phonovibrograms is presented. The phonovibrogram is an image representation of the spatiotemporal pattern of vocal fold vibration and constitutes the basis for a computer-based analysis of laryngeal dynamics. The features extracted from the wavelet transform are shown to be closely related to a basic set of video-based measurements categorized by the European Laryngological Society for a subjective assessment of pathologic voices. The wavelet-based analysis further offers information about irregularity and lateral asymmetry and async...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

A Novel Use of Transfer Function Estimation for Early Assessment of Brain Injury Outcome
Normal blood flow in the brain as a response to pressure fluctuations is commonly referred to as cerebral autoregulation. Linear, nonparametric models of cerebral autoregulation were estimated for 77 human subjects afflicted with brain injury, with mean arterial pressure used as input, and invasively measured regional cerebral blood flow used as output. The data were continuously monitored from the beginning of subject hospital stay. Mean transfer function gain as a function of frequency was calculated for each subject over a limited time window spanning 48 h, starting postsurgery. The mean transfer function gain of...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Human Brain Distinctiveness Based on EEG Spectral Coherence Connectivity
In this study, we propose a novel approach that fuses spectral coherence-based connectivity between different brain regions as a possibly viable biometric feature. The proposed approach is tested on a large dataset of subjects (N = 108) during eyes-closed (EC) and eyes-open (EO) resting state conditions. The obtained recognition performance shows that using brain connectivity leads to higher distinctiveness with respect to power-spectrum measurements, in both the experimental conditions. Notably, a 100% recognition accuracy is obtained in EC and EO when integrating functional connectivity between regions in t...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Murine Heart Volume: Numerical Comparison and Calibration of Conductance Catheter Models
A full set of finite-element method (FEM) studies of the catheter within a cylindrical cuvette and within an elliptical cuvette are presented along with novel insight on the fundamental electromagnetic properties of the catheter. An in vitro experiment with modified small mouse pressure–volume catheters was conducted and the results are presented as a validation of the FEM models. In addition, sensitivity analysis on the electrode size and position is conducted and the results allow for a novel calibration factor based on catheter geometry to be presented. This calibration factor is used in conjunction with Wei ...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Automated Grouping of Action Potentials of Human Embryonic Stem Cell-Derived Cardiomyocytes
Methods for obtaining cardiomyocytes from human embryonic stem cells (hESCs) are improving at a significant rate. However, the characterization of these cardiomyocytes (CMs) is evolving at a relatively slower rate. In particular, there is still uncertainty in classifying the phenotype (ventricular-like, atrial-like, nodal-like, etc.) of an hESC-derived cardiomyocyte (hESC-CM). While previous studies identified the phenotype of a CM based on electrophysiological features of its action potential, the criteria for classification were typically subjective and differed across studies. In this paper, we use techniques from signa...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Control of an Electromechanical Hydrocephalus Shunt—a New Approach
Hydrocephalus is characterized by an excessive accumulation of cerebrospinal fluid (CSF). Therapeutically, an artificial pressure relief valve (so-called shunt) is implanted which opens in case of increased intracranial pressure (ICP) and drains CSF into another body compartment. Today, available shunts are of a mechanical nature and drainage depends on the pressure drop across the shunt. According to the latest data, craniospinal compliance is considered to be even more important than mean ICP alone. In addition, ICP is not constant but varies due to several influences. In fact, heartbeat-related ICP waveform patterns dep...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research

Iterative Reconstruction for X-Ray Computed Tomography Using Prior-Image Induced Nonlocal Regularization
In this study, to realize radiation dose reduction by reducing the X-ray tube current and exposure time (mAs) in repeated CT scans, we propose a prior-image induced nonlocal (PINL) regularization for statistical iterative reconstruction via the penalized weighted least-squares (PWLS) criteria, which we refer to as “PWLS-PINL”. Specifically, the PINL regularization utilizes the redundant information in the prior image and the weighted least-squares term considers a data-dependent variance estimation, aiming to improve current low-dose image quality. Subsequently, a modified iterative successive overrelaxation ...
Source: IEEE Transactions on Biomedical Engineering - August 19, 2014 Category: Biomedical Engineering Source Type: research