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Biomedical Engineering, IEEE Transactions on

Issue 4 • Date April 2008

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Displaying Results 1 - 25 of 29
  • [Front cover]

    Publication Year: 2008 , Page(s): C1
    Save to Project icon | Request Permissions | PDF file iconPDF (225 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Biomedical Engineering publication information

    Publication Year: 2008 , Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (40 KB)  
    Freely Available from IEEE
  • Table of contents

    Publication Year: 2008 , Page(s): 1253 - 1254
    Save to Project icon | Request Permissions | PDF file iconPDF (122 KB)  
    Freely Available from IEEE
  • Simulation of Patient Specific Cervical Hip Fracture Surgery With a Volume Haptic Interface

    Publication Year: 2008 , Page(s): 1255 - 1265
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2631 KB) |  | HTML iconHTML  

    The interest for surgery simulator systems with anatomical models generated from authentic patient data is growing as these systems evolve. With access to volumetric patient data, e.g., from a computer tomography scan, haptic and visual feedback can be created directly from this dataset. This opens the door for patient specific simulations. Hip fracture surgery is one area where simulator systems is useful to train new surgeons and plan operations. To simulate the drilling procedure in this type of surgery, a repositioning of the fractured bone into correct position is first needed. This requires a segmentation process in which the bone segments are identified and the position of the dislocated part is determined. The segmentation must be automatic to cope with the large amount of data from the computer tomography scan. This work presents the first steps in the development of a hip fracture surgery simulation with patient specific models. Visual and haptic feedback is generated from the computer tomography data by simulating fluoroscopic images and the drilling process. We also present an automatic segmentation method to identify the fractured bone and determine the dislocation. This segmentation method is based on nonrigid registration with the Morphon method. View full abstract»

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  • A Mathematical Model of Respiratory and Biothermal Dynamics in Brain Hypothermia Treatment

    Publication Year: 2008 , Page(s): 1266 - 1278
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB) |  | HTML iconHTML  

    Brain hypothermia treatment (BHT) requires proper mechanical ventilation and therapeutic cooling. The cooling strategy for BHT has been mainly discussed in the literature while little information is available on the respiratory management. We first developed a mathematical model that integrates the respiratory and biothermal dynamics to discuss the simultaneous managements of mechanical ventilation and therapeutic cooling. The effect of temperature on the linear approximations of hemoglobin-oxygen dissociation, together with temperature dependency of metabolism, is introduced during modeling to combine the respiratory system with the biothermal system. By comparing its transient behavior with published data, the model is verified qualitatively and then quantitatively. Second, model-based simulation of the current respiratory management in BHT suggests reduction of minute ventilation in reference to cooled brain temperature to stabilize the states of blood and brain oxygenation. Lastly, the relationship between cooling temperature and minute ventilation is approximated by a linear first-order transfer function of static gain 0.61 min-1degC-1 and time constant 8.9 h, which is used to develop a feedforward control to tune the mechanical ventilator in concert with temperature regulation of the cooling blanket. Discussion of the model encourages further studies that provide direct evidence from clinical experiments. View full abstract»

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  • Numerical Design of Experiment for Sensitivity Analysis—Application to Skin Burn Injury Prediction

    Publication Year: 2008 , Page(s): 1279 - 1290
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (813 KB) |  | HTML iconHTML  

    Temperature evolution and skin burn process resulting from a laser radiation exposure are investigated in this paper. Transient temperature in skin is numerically estimated using a 1-D multilayered model based on Penne's equation. The degree of burn injury is numerically evaluated by using an Arrhenius-type function. Unfortunately, most of the mathematical model parameters are not well defined in literature. Thus, a sensitivity analysis has been performed in order to evaluate the effect of each parameters inaccuracy on temperature estimation and on burn injuries prediction (according to several authors' characterization). Investigated parameters uncertainties that crucially invalidate the thermal model are as follows: epidermis and dermis volumetric heat, extinction coefficient, and skin thickness of the affected area. Considering the damage prediction, the activation energy is a key parameter for the validation of an efficient predictive tool. View full abstract»

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  • Relations Between the Timing of the Second Heart Sound and Aortic Blood Pressure

    Publication Year: 2008 , Page(s): 1291 - 1297
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (876 KB) |  | HTML iconHTML  

    The second heart sound (S2) is triggered by an aortic valve closure as a result of the ventricular-arterial interaction of the cardiovascular system. The objective of this paper is to investigate the timing of S2 in response to the changes in hemodynamic parameters and its relation to aortic blood pressure (BP). An improved model of the left ventricular-arterial interaction was proposed based on the combination of the newly established pressure source model of the ventricle and the nonlinear pressure-dependent compliance model of the arterial system. The time delay from the onset of left ventricular pressure rise to the onset of S2 (RS2) was used to measure the timing of S2. The results revealed that RS2 bears a strong negative correlation with both systolic blood pressure and diastolic blood pressure under the effect of changing peripheral resistance, heart rate, and contractility. The results were further validated by a series of measurements of 16 normal subjects submitted to dynamic exercise. This study helps understand the relationship between the timing of S2 and aortic BP under various physiological and pathological conditions. View full abstract»

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  • Modeling Cellular Metabolism and Energetics in Skeletal Muscle: Large-Scale Parameter Estimation and Sensitivity Analysis

    Publication Year: 2008 , Page(s): 1298 - 1318
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2535 KB) |  | HTML iconHTML  

    Skeletal muscle plays a major role in the regulation of whole-body energy metabolism during physiological stresses such as ischemia, hypoxia, and exercise. Current experimental techniques provide relatively little in vivo data on dynamic responses of metabolite concentrations and metabolic fluxes in skeletal muscle to such physiological stimuli. As a complementary approach to experimental measurements and as a framework for quantitatively analyzing available in vivo data, a physiologically based model of skeletal muscle cellular metabolism and energetics is developed. This model, which incorporates key transport and reaction processes, is based on dynamic mass balances of 30 chemical species in capillary (blood) and tissue (cell) domains. The reaction fluxes in the cellular domain are expressed in terms of a generalized Michaelis-Menten equation involving energy controller ratios ATP/ADP and NADH/NAD+. This formalism introduces a large number of unknown parameters (~90). Estimating these parameters from in vivo sparse data and evaluating dynamic sensitivities of the model outputs with respect to these parameters is a challenging problem. Parameter estimation is accomplished using an efficient, nonlinear, constraint-based, optimization algorithm that minimizes differences between available experimental data and corresponding model outputs by explicitly utilizing equality constraints on resting fluxes and concentrations. With the estimated parameter values, the model is able to simulate dynamic responses to reduced blood flow (ischemia) of key metabolite concentrations and metabolic fluxes, both measured and nonmeasured. A general parameter sensitivity analysis is carried out to determine and characterize the parameters having the most and least effects on the measured outputs. View full abstract»

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  • An ECG Signals Compression Method and Its Validation Using NNs

    Publication Year: 2008 , Page(s): 1319 - 1326
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (665 KB) |  | HTML iconHTML  

    This paper presents a new algorithm for electrocardiogram (ECG) signal compression based on local extreme extraction, adaptive hysteretic filtering and Lempel-Ziv-Welch (LZW) coding. The algorithm has been verified using eight of the most frequent normal and pathological types of cardiac beats and an multi-layer perceptron (MLP) neural network trained with original cardiac patterns and tested with reconstructed ones. Aspects regarding the possibility of using the principal component analysis (PCA) to cardiac pattern classification have been investigated as well. A new compression measure called ldquoquality score,rdquo which takes into account both the reconstruction errors and the compression ratio, is proposed. View full abstract»

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  • Truncated Total Least Squares: A New Regularization Method for the Solution of ECG Inverse Problems

    Publication Year: 2008 , Page(s): 1327 - 1335
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1199 KB) |  | HTML iconHTML  

    The reconstruction of epicardial potentials (EPs) from body surface potentials (BSPs) can be characterized as an ill-posed inverse problem which generally requires a regularized numerical solution. Two kinds of errors/noise: geometric errors and measurement errors exist in the ECG inverse problem and make the solution of such problem more difficulty. In particular, geometric errors will directly affect the calculation of transfer matrix A in the linear system equation AX = B. In this paper, we have applied the truncated total least squares (TTLS) method to reconstruct EPs from BSPs. This method accounts for the noise/errors on both sides of the system equation and treats geometric errors in a new fashion. The algorithm is tested using a realistically shaped heart-lung-torso model with inhomogeneous conductivities. The h-adaptive boundary element method [h-BEM, a BEM mesh adaptation scheme which starts from preset meshes and then refines (adds/removes) grid with fixed order of interpolation function and prescribed numerical accuracy] is used for the forward modeling and the TTLS is applied for inverse solutions and its performance is also compared with conventional regularization approaches such as Tikhonov and truncated single value decomposition (TSVD) with zeroth-, first-, and second-order. The simulation results demonstrate that TTLS can obtain similar results in the situation of measurement noise only but performs better than Tikhonov and TSVD methods where geometric errors are involved, and that the zeroth-order regularization is the optimal choice for the ECG inverse problem. This investigation suggests that TTLS is able to robustly reconstruct EPs from BSPs and is a promising alternative method for the solution of ECG inverse problems. View full abstract»

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  • Respiratory Sounds Compression

    Publication Year: 2008 , Page(s): 1336 - 1343
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (651 KB) |  | HTML iconHTML  

    Recently, with the advances in digital signal processing, compression of biomedical signals has received great attention for telemedicine applications. In this paper, an adaptive transform coding-based method for compression of respiratory and swallowing sounds is proposed. Using special characteristics of respiratory sounds, the recorded signals are divided into stationary and nonstationary portions, and two different bit allocation methods (BAMs) are designed for each portion. The method was applied to the data of 12 subjects and its performance in terms of overall signal-to-noise ratio (SNR) values was calculated at different bit rates. The performance of different quantizers was also considered and the sensitivity of the quantizers to initial conditions has been alleviated. In addition, the fuzzy clustering method was examined for classifying the signal into different numbers of clusters and investigating the performance of the adaptive BAM with increasing the number of classes. Furthermore, the effects of assigning different numbers of bits for encoding stationary and nonstationary portions of the signal were studied. The adaptive BAM with variable number of bits was found to improve the SNR values of the fixed BAM by 5 dB. Last, the possibility of removing the training part for finding the parameters of adaptive BAMs for each individual was investigated. The results indicate that it is possible to use a predefined set of BAMs for all subjects and remove the training part completely. Moreover, the method is fast enough to be implemented for real-time application. View full abstract»

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  • Robust Unsupervised Detection of Action Potentials With Probabilistic Models

    Publication Year: 2008 , Page(s): 1344 - 1354
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB) |  | HTML iconHTML  

    We develop a robust and fully unsupervised algorithm for the detection of action potentials from extracellularly recorded data. Using the continuous wavelet transform allied to probabilistic mixture models and Bayesian probability theory, the detection of action potentials is posed as a model selection problem. Our technique provides a robust performance over a wide range of simulated conditions, and compares favorably to selected supervised and unsupervised detection techniques. View full abstract»

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  • Analysis and Measurements of Magnetic Field Exposures for Healthcare Workers in SelectedMR Environments

    Publication Year: 2008 , Page(s): 1355 - 1364
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (797 KB) |  | HTML iconHTML  

    There are concerns about workers repeatedly exposed to magnetic fields exceeding regulatory limits with respect to modern magnetic resonance imaging (MRI). As a result, there is need for an ambulatory magnetic field dosimeter capable of measuring these fields in and around an MRI scanner in order to evaluate the regulatory guidelines and determine any underlying exposure risks. This study presents results of tri-axial measurements using an ambulatory magnetic field dosimeter worn by workers during normal working shifts. We recorded and analyzed magnetic field exposures in and around 1.5 T, 2 T, and 4 T magnets during routine patient procedures. The data was integrated and averaged over time and evaluated against the latest exposure standards. Time-varying magnetic fields occur when individuals move through spatially non-uniform static magnetic fields or during gradient-pulsed magnetic fields or a combination of both. Our previous numerical analysis shows that at certain positions surrounding the MRI scanner ends, such fields may induce current densities and electric fields that may exceed the relevant EU, ICNIRP, and IEEE standards. A high-speed acquisition version of the dosimeter measured gradient-pulsed fields at positions accessible by MRI workers near the scanner ends, and the results were evaluated and compared against the numerical simulations and the standards. Our measurements confirm that workers can be exposed to magnetic fields exceeding the guidelines at positions near the gradient coil ends during clinical imaging and a high degree of correlation exists with the numerical results. While the time-weighted average magnetic field exposures in 1.5 T, 2 T, and 4 T were all within the regulatory limits during static magnetic field measurements, the peak limits for the head can be exceeded in some circumstances. This study presents a small number of routine shifts of data that provide indicative results of magnetic field exposure in real situations. View full abstract»

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  • Designing the Optical Interface of a Transcutaneous Optical Telemetry Link

    Publication Year: 2008 , Page(s): 1365 - 1373
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (890 KB) |  | HTML iconHTML  

    Optical telemetry has long been an option for transcutaneous data transfer and has been used in various types of implanted systems. This telemetry modality and the efficiency of these optical links are becoming ever more important as higher bandwidth sources such as cortical recording arrays are being implemented in implanted systems. The design of the transmitter-skin-receiver interface (the ldquooptical interfacerdquo) is paramount to the operation of a transcutaneous optical telemetry link. This interface functions to achieve sufficient receiver signal power for data communication. This paper describes a mathematical analysis and supporting data that quantitatively describes the relationship between the primary interface design parameters. These parameters include the thickness of the skin through which the light is transmitted, the size of the integration area of the optics, the degree of transmitter-receiver misalignment, the efficiency of the optics system, and the emitter power. The particular combination of these parameters chosen for the hardware device will determine the receiver signal power and, therefore, the data quality for the link. This paper demonstrates some of the tradeoffs involved in the selection of these design parameters and provides suggestions for link design. This analysis may also be useful for transcutaneous optical powering systems. View full abstract»

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  • A Telemetric Pressure Sensor System for Biomedical Applications

    Publication Year: 2008 , Page(s): 1374 - 1381
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1087 KB) |  | HTML iconHTML  

    A new implantable pressure sensor for long-term monitoring of intracranial pressure is presented. The sensor is powered by telemetry and can be interrogated wirelessly. A capacitive pressure transducer, whose capacitance is converted to a frequency-encoded signal by an application-specific integrated circuit (ASIC), senses the absolute pressure. The pressure-encoded signal, the ASIC input voltage, and onboard calibration parameters are transmitted to an external reading unit. The proposed novel packaging solution is designed for long-term stability and reliability of the sensor. The accuracy of sensor at body temperature is better than 2 mbar across a pressure range of 600-1200 mbar. The sensor is 13 mm in diameter and 4.5 mm in height. View full abstract»

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  • Analysis of Cultured Neuronal Networks Using Intraburst Firing Characteristics

    Publication Year: 2008 , Page(s): 1382 - 1390
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1389 KB) |  | HTML iconHTML  

    It is an open question whether neuronal networks, cultured on multielectrode arrays, retain any capability to usefully process information (learning and memory). A necessary prerequisite for learning is that stimulation can induce lasting changes in the network. To observe these changes, one needs a method to describe the network in sufficient detail, while stable in normal circumstances. We analyzed the spontaneous bursting activity that is encountered in dissociated cultures of rat neocortical cells. Burst profiles (BPs) were made by estimating the instantaneous array-wide firing frequency. The shape of the BPs was found to be stable on a time scale of hours. Spatiotemporal detail is provided by analyzing the instantaneous firing frequency per electrode. The resulting phase profiles (PPs) were estimated by aligning BPs to their peak spiking rate over a period of 15 min. The PPs reveal a stable spatiotemporal pattern of activity during bursts over a period of several hours, making them useful for plasticity and learning studies. We also show that PPs can be used to estimate conditional firing probabilities. Doing so, yields an approach in which network bursting behavior and functional connectivity can be studied. View full abstract»

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  • Simulation Studies of Ultrashort, High-Intensity Electric Pulse Induced Action Potential Block in Whole-Animal Nerves

    Publication Year: 2008 , Page(s): 1391 - 1398
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1136 KB) |  | HTML iconHTML  

    A theoretical study of possible neuromuscular incapacitation based on the application of high-intensity, ultrashort electric pulses is presented. The analysis is applied to a rat, but the approach is general and can be extended to any whole-animal and applies for any arbitrary pulse waveform. It is hypothesized that repeatable and reversible action potential blocks in nerves can be attained based on the electroporation mechanism. Our numerical studies are based on the Hodgkin-Huxley distributed circuit representation of nerves, and incorporate a nodal analysis for the time-dependent and volumetric perturbing potentials and internal electric fields in whole animals. The predictions are compared to actual 600-ns experimental reports on rats and shown to be in very good agreement. Effective strength-duration plots for neuromuscular incapacitation are also generated. View full abstract»

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  • Optimal Filter Design to Compute the Mean of Cardiovascular Pressure Signals

    Publication Year: 2008 , Page(s): 1399 - 1407
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1093 KB) |  | HTML iconHTML  

    The mean pressure is a term used to describe the baseline trend of physiological pressure signals that excludes fluctuations due to the cardiac cycle and, in some cases, the respiratory cycle. In many clinical applications and bedside monitoring devices, the mean pressure is estimated with a 3-8 s moving average. We suggest that the mean pressure is best defined in terms of its frequency domain properties. This definition makes it possible to determine solutions that are both optimal and practical. We demonstrate that established methods of optimal finite impulse response (FIR) filter design produce estimates of the mean pressure that are significantly more accurate than the moving average. These filters have no more computational cost, are less sensitive to artifact, have shorter delays, and greater sensitivity to acute events. View full abstract»

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  • Linear Electrode Arrays for Stimulation and Recording Within Cardiac Tissue Space Constants

    Publication Year: 2008 , Page(s): 1408 - 1414
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (514 KB) |  | HTML iconHTML  

    In this paper, we document a fabrication process that yields linear arrays of rectangular platinum black electrodes spaced 25 mum apart with edge-to-edge separation of 20 mum. The spatial arrangement is therefore sufficiently fine to insure stimulation and recording within cardiac tissue space constants, as six electrodes with dimensions of either, 5x100 mum2, 5x250 mum2 or 5x500 mum2 were positioned in a 130-mum span in the arrays. Despite the small electrode sizes and available surface areas, favorable impedance characteristics were identifed. Averages ranged from 111 kOmega to 146 kOmega at 0.5 Hz and from 14 kOmega to 39 kOmega at 500 Hz. Differences in impedances between the electrode sizes tested were small. Potential differences (deltaPhis) recorded using the two central electrodes during stimulation with combinations at separations of only 75 mum , 100 mum , and 125 mum had low signal noise. As a preliminary test of the use of these arrays for possible application to impedance measurements in cardiac tissue, the deltaPhis recorded during stimulation were compared to deltaPhis obtained from finite-difference simulations using an isotropic volume conductor model. Anticipated decays in with widening electrode separation identified in those simulations matched the decays in the recorded s closely. These findings are significant because they suggest intracellular and interstitial microimpedance mesurements in heart experiments will be straightforward. View full abstract»

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  • New Accelerometric Method to Discriminate Between Asymptomatic Subjects and Patients With Medial Knee Osteoarthritis During 3-D Gait

    Publication Year: 2008 , Page(s): 1415 - 1422
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (621 KB) |  | HTML iconHTML  

    This study presents a new method to estimate 3-D linear accelerations at tibial and femoral functional coordinate systems. The method combines the use of 3-D accelerometers, 3-D gyroscopes and reflective markers rigidly fixed on an exoskeleton and, a functional postural calibration method. Marker positions were tracked by a six-camera optoelectronic system (VICON 460, Oxford Metrics). The purpose of this study was to determine if this method could discriminate between medial osteoarthritic and asymptomatic knees during gait. Nine patients with osteoarthritic knees and nine asymptomatic control subjects were included in this study. Eighteen parameters representing maximal, minimal, and range of acceleration values were extracted during the loading and preswing to mid-swing phase periods, and were compared in both groups. Results show good discriminative capacity of the new method. Eight parameters were significantly different between both groups. The proposed method has the potential to be used in comprehending and monitoring gait strategy in patients with osteoarthritic knee. View full abstract»

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  • The Effect of Resultant Force at the Pushrim on Shoulder Kinetics During Manual Wheelchair Propulsion: A Simulation Study

    Publication Year: 2008 , Page(s): 1423 - 1431
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (898 KB) |  | HTML iconHTML  

    The aim of this study was to determine, by simulation on real data, the effect of modifying the direction or effectiveness of a given force amplitude on the load sustained by the shoulder estimated by joint forces and moments. Kinematics and kinetics data were recorded on 14 manual wheelchair users (68.2plusmn5.2 years) for 10 s at sub-maximal speed (0.96-1.01 m/s). The simulation consisted in modifying force effectiveness at the pushrim while maintaining the same initial force amplitude. Shoulder kinetics were computed for simulated resultant forces from radial to tangent directions and also for initial force effectiveness. The results show that as the force was simulated tangent to the wheel, there was a significant increase in the average proximal and anterior shoulder joint forces. Also, significant increases in average internal rotation, flexion in the sagittal and horizontal plane moments were reported. Higher shoulder kinetics could accelerate the onset of fatigue and increase the risk of injury. A single-case analysis revealed an improvement window for force effectiveness (~10%) in which shoulder kinetics were not substantially increased. Our results provide useful information on what would happen to shoulder kinetics if we were able to teach manual wheelchair users to modify their force pattern at the pushrim. The results suggest that for an elderly population, it is not wise to aim at producing a mechanically optimal resultant force at the pushrim (i.e., tangent). Smaller increases of the initial force effectiveness would be preferable. View full abstract»

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  • Feasibility of Sonophoretic Delivery for Effective Skin Optical Clearing

    Publication Year: 2008 , Page(s): 1432 - 1437
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    In an attempt to find a noninvasive way to improve the efficacy of skin optical clearing with topical application of optical clearing agents (OCA), we exploited the effect of ultrasound on optical clearing of intact skin in vitro. Changes in optical transmittance and diffuse reflectance of the porcine skin under different treatment procedures were measured by a UV/Vis/NIR spectrophotometer. Clearing capability of glycerol or propylene glycol was much improved with the simultaneous application of ultrasound with a frequency of 1 MHz and a power of 0.75 W over a 3-cm probe. Light transmittance at 470 and 1276 nm increased by 112%-128% and 54%-65%, respectively. The most significant effect was seen where skin was treated with the combination of ultrasound and the chemical enhancer azone, resulting in a 2.3-fold increase of optical clearing at 1276 nm. We demonstrate the feasibility of using sonophoretic delivery methods to improve skin optical clearing with topical application of OCA. View full abstract»

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  • Anatomical Optical Coherence Tomography for Long-Term, Portable, Quantitative Endoscopy

    Publication Year: 2008 , Page(s): 1438 - 1446
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2887 KB) |  | HTML iconHTML  

    In this paper, we report on anatomical optical coherence tomography, a catheter-based optical modality designed to provide quantitative sectional images of internal hollow organ anatomy over extended observational periods. We consider the design and performance of an instrument and its initial intended application in the human upper airway for the characterization of obstructive sleep apnea (OSA). Compared with current modalities, the technique uniquely combines quantitative imaging, bedside operation, and safety for use over extended periods of time with no cumulative dose limit. Our experiments show that the instrument is capable of imaging subjects during sleep, and that it can record dynamic changes in airway size and shape. View full abstract»

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  • The Influence of Porous Silicon on Axonal Outgrowth in Vitro

    Publication Year: 2008 , Page(s): 1447 - 1449
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (553 KB) |  | HTML iconHTML  

    Axonal outgrowth on smooth and porous silicon surfaces was studied in organ culture. The pore size of the silicon substrata varied between 100 and 1500 nm. We found that axons preferred to grow and elongate on porous silicon surfaces only when pores of (150-500 nm) are available. View full abstract»

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  • Investigation of Short-Term Changes in Visual Evoked Potentials With Windowed Adaptive Chirplet Transform

    Publication Year: 2008 , Page(s): 1449 - 1454
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (554 KB) |  | HTML iconHTML  

    We propose a new application of the adaptive chirplet transform that involves partitioning signals into non-overlapping sequential segments. From these segments, the local time-frequency structures of the signal are estimated by using a four-parameter chirplet decomposition. Entitled the windowed adaptive chirplet transform (windowed ACT), this approach is applied to the analysis of visual evoked potentials (VEPs). It can provide a unified and compact representation of VEPs from the transient buildup to the steady-state portion with less computational cost than its non-windowed counterpart. This paper also details a method to select the optimal window length for signal segmentation. This approach will be useful for long-term signal monitoring as well as for signal feature extraction and data compression. View full abstract»

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Aims & Scope

IEEE Transactions on Biomedical Engineering contains basic and applied papers dealing with biomedical engineering. Papers range from engineering development in methods and techniques with biomedical applications to experimental and clinical investigations with engineering contributions.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Bin He
Department of Biomedical Engineering