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Biomedical Engineering

This page shows you the most recent publications within this specialty of the MedWorm directory. This is page number 20.

A Novel Spatiotemporal Analysis of Peri-Ictal Spiking to Probe the Relation of Spikes and Seizures in Epilepsy.
Abstract The relation between epileptic spikes and seizures is an important but still unresolved question in epilepsy research. Preclinical and clinical studies have produced inconclusive results on the causality or even on the existence of such a relation. We set to investigate this relation taking in consideration seizure severity and spatial extent of spike rate. We developed a novel automated spike detection algorithm based on morphological filtering techniques and then tested the hypothesis that there is a pre-ictal increase and post-ictal decrease of the spatial extent of spike rate. Peri-ictal (around seizur...
Source: Annals of Biomedical Engineering - April 17, 2014 Category: Biomedical Engineering Authors: Krishnan B, Vlachos I, Faith A, Mullane S, Williams K, Alexopoulos A, Iasemidis L Tags: Ann Biomed Eng Source Type: research

Design considerations and quantitative assessment for the development of percutaneous mitral valve stent
Abstract: Percutaneous heart valve replacement is gaining popularity, as more positive reports of satisfactory early clinical experiences are published. However this technique is mostly used for the replacement of pulmonary and aortic valves and less often for the repair and replacement of atrioventricular valves mainly due to their anatomical complexity. While the challenges posed by the complexity of the mitral annulus anatomy cannot be mitigated, it is possible to design mitral stents that could offer good anchorage and support to the valve prosthesis. This paper describes four new Nitinol based mitral valve designs wit...
Source: Medical Engineering and Physics - April 17, 2014 Category: Biomedical Engineering Authors: Gideon Praveen Kumar, Fangsen Cui, Hui Qun Phang, Boyang Su, Hwa Liang Leo, Jimmy Kim Fatt Hon Tags: Papers Source Type: research

Effect of amplitude and duration of impulsive pressure on endothelial permeability in in vitro fluid percussion trauma
Conclusions: The changes in intracranial pressure during head impact impair endothelial barrier function by the disruption of the integrity of endothelial cell-cell junctions, and the degree of increase in endothelial permeability depends on the amplitude, duration, and direction (compressive and tensile) of the impulsive pressure. (Source: BioMedical Engineering OnLine)
Source: BioMedical Engineering OnLine - April 16, 2014 Category: Biomedical Engineering Authors: Hiromichi NakadateKoji InuzukaSuguru AkanumaAkira KakutaShigeru Aomura Source Type: research

Reducing the impact of insulin sensitivity variability on glycaemic outcomes using separate stochastic models within the STAR glycaemic protocol
Conclusions: SI levels increase significantly, while variability decreases during the first 18 hours of a patients stay in ICU. Virtual trials, using a separate stochastic model for this period, demonstrated a reduction in variability and hypoglycaemia during the first 18 hours without adversely affecting the overall level of control. Thus, use of multiple models can reduce the impact of SI variability during model-based glycaemic control. (Source: BioMedical Engineering OnLine)
Source: BioMedical Engineering OnLine - April 16, 2014 Category: Biomedical Engineering Authors: Felicity ThomasChristopher PrettyLiam FiskGeoffrey ShawJ ChaseThomas Desaive Source Type: research

Microtubule shuttles on kinesin-coated glass micro-wire tracks.
Abstract Gliding of microtubule filaments on surfaces coated with the motor protein kinesin has potential applications for nano-scale devices. The ability to guide the gliding direction in three dimensions allows the fabrication of tracks of arbitrary geometry in space. Here, we achieve this by using kinesin-coated glass wires of micrometer diameter range. Unlike previous methods in which the guiding tracks are fixed on flat two-dimensional surfaces, the flexibility of glass wires in shape and size facilitates building in-vitro devices that have deformable tracks. PMID: 24737133 [PubMed - as supplied by publish...
Source: Biomedical Microdevices - April 16, 2014 Category: Biomedical Engineering Authors: Kim K, Liao AL, Sikora A, Oliveira D, Nakazawa H, Umetsu M, Kumagai I, Adschiri T, Hwang W, Teizer W Tags: Biomed Microdevices Source Type: research

Evaluation of the effect of polymeric microneedle arrays of varying geometries in combination with a high-velocity applicator on skin permeability and irritation.
In conclusion, a faster application speed could significantly enhance skin permeability and damage and compensate for insufficient penetration of the larger tip radius and shorter needles, which are also important factors for effective insertion. PMID: 24733417 [PubMed - as supplied by publisher] (Source: Biomedical Microdevices)
Source: Biomedical Microdevices - April 15, 2014 Category: Biomedical Engineering Authors: Watanabe T, Hagino K, Sato T Tags: Biomed Microdevices Source Type: research

Analysis of the effects of surface stiffness on the contact interaction between a finger and a cylindrical handle using a three-dimensional hybrid model
Abstract: Contact interactions between the hand and handle, such as the contact surface softness and contact surface curvature, will affect both physical effort and musculoskeletal fatigue, thereby the comfort and safety of power tool operations. Previous models of hand gripping can be categorized into two groups: multi-body dynamic models and finite element (FE) models. The goal of the current study is to develop a hybrid FE hand gripping model, which combines the features of conventional FE models and multi-body dynamic models. The proposed model is applied to simulate hand-gripping on a cylindrical handle with covering ...
Source: Medical Engineering and Physics - April 15, 2014 Category: Biomedical Engineering Authors: John Z. Wu, Ren G. Dong, Christopher M. Warren, Daniel E. Welcome, Thomas W. McDowell Tags: Papers Source Type: research

Prophylactic vertebroplasty can decrease the fracture risk of adjacent vertebrae: An in vitro cadaveric study
In this study we determined whether prophylactic vertebroplasty can also reduce the fracture risk under off-axis loads.In a previous study, we tested vertebral bodies that were loaded axially or 20° off-axis representing vertebrae in an unfractured spine or vertebrae adjacent to a wedge fracture, respectively. In the current study, vertebral failure load and stiffness of our previously tested vertebral bodies were compared to those of a new group of vertebral bodies that were filled with bone cement and then loaded 20° off-axis. These vertebral bodies represented adjacent-level vertebrae with prophylactic bone cement fil...
Source: Medical Engineering and Physics - April 15, 2014 Category: Biomedical Engineering Authors: René Aquarius, Jasper Homminga, Allard Jan Frederik Hosman, Nico Verdonschot, Esther Tanck Tags: Technical Notes Source Type: research

A numerical investigation of flow around octopus-like arms: near-wake vortex patterns and force development.
Abstract The fluid dynamics of cephalopods has so far received little attention in the literature, due to their complexity in structure and locomotion. The flow around octopuses, in particular, can be complicated due to their agile and dexterous arms, which frequently display some of the most diverse mechanisms of motion. The study of this flow amounts to a specific instance of the hydrodynamics problem for rough tapered cylinder geometries. The outstanding manipulative and locomotor skills of octopuses could inspire the development of advanced robotic arms, able to operate in fluid environments. Our primary aim wa...
Source: Computer Methods in Biomechanics and Biomedical Engineering - April 14, 2014 Category: Biomedical Engineering Authors: Kazakidi A, Vavourakis V, Tsakiris DP, Ekaterinaris JA Tags: Comput Methods Biomech Biomed Engin Source Type: research

Determination of body segment masses and centers of mass using a force plate method
We would like to call the readers’ attention to a serious algebraic error we identified in the technical note co-authored by Damavandi, Farahpour, and Allard, entitled “Determination of body segment masses and centers of mass using a force plate method in individuals of different morphology,” and published in Medical Engineering and Physics . Subject-specific body segment masses and center of mass (COM) locations are used in biomechanical analyses aiming to assess accurately joint forces and moments arising during any activity. There is no direct way to measure these variables in a living individual, and therefore, v...
Source: Medical Engineering and Physics - April 14, 2014 Category: Biomedical Engineering Authors: Christopher Ramsey, Jongeun Choi, Clark J. Radcliffe, Jacek Cholewicki, John M. Popovich Jr, N. Peter Reeves, M. Cody Priess Tags: Letters to the Editor Source Type: research

Investigation of continuous-batch mode of two-stage culture of Nannochloropsis sp. for lipid production.
In this study, the effects of culture conditions and modes on biomass productivity and lipid productivity of Nannochloropsis sp. in the two stages were comprehensively investigated. The optimal culture conditions for the two stages, aiming to high biomass productivity and lipid productivity respectively, were consistent, i.e., CO2 content in aeration (1 %), phosphorus concentration in medium (181 μmol/L), incident light intensity (150 μE/(m(2)s)), temperature (25 °C). Different culture modes of the two stages were compared. The overall lipid productivity of the two-stage continuous-batch mode achieved 0.123 g/(L d...
Source: Bioprocess and Biosystems Engineering - April 13, 2014 Category: Biomedical Engineering Authors: Zhang D, Xue S, Sun Z, Liang K, Wang L, Zhang Q, Cong W Tags: Bioprocess Biosyst Eng Source Type: research

M13 bacteriophage production for large-scale applications.
Abstract Bacteriophage materials have the potential to revolutionize medicine, energy production and storage, agriculture, solar cells, optics and many other fields. To fulfill these needs, this study examined critical process parameters during phage propagation to increase phage production capability. A representative scale-down system was created in tube spin reactors to allow parallel experimentation with single- and multi-variable analysis. Temperature, harvest time, media composition, feed regime, bacteriophage, and bacteria concentration were analyzed in the scale-down system. Temperature, media composition, ...
Source: Bioprocess and Biosystems Engineering - April 13, 2014 Category: Biomedical Engineering Authors: Warner CM, Barker N, Lee SW, Perkins EJ Tags: Bioprocess Biosyst Eng Source Type: research

Validation of Algorithms for the Estimation of Pulse Transit Time: Where do We Stand Today? Response to Commentaries by Papaioannou et al.
PMID: 24728865 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering)
Source: Annals of Biomedical Engineering - April 12, 2014 Category: Biomedical Engineering Authors: Gaddum NR, Alastruey J, Chowienczyk P, Schaeffter T Tags: Ann Biomed Eng Source Type: research

Measuring Subject Specific Muscle Model Parameters of the First Dorsal Interosseous In Vivo.
This study focused on the First Dorsal interosseous (FDI) given its unique function as the sole abductor of the second metacarpophalangeal joint. There were two purposes to this study: (1) to describe the procedures that can be used in vivo to determine the properties of a model of the FDI. (2). To determine the model parameters required to characterize the FDI for a group of four subjects. Parameters were determined using ultrasound imaging and a custom-built finger dynamometer. Some parameters were measured directly while other parameters had to be estimated using a least-squares criterion. For example, the parameters fo...
Source: Annals of Biomedical Engineering - April 12, 2014 Category: Biomedical Engineering Authors: Infantolino BW, Challis JH Tags: Ann Biomed Eng Source Type: research

Beyond MAP Estimation With the Track-Oriented Multiple Hypothesis Tracker
The track-oriented multiple hypothesis tracker (TOMHT) is a popular algorithm for tracking multiple targets in a cluttered environment. In tracking parlance it is known as a multi-scan, maximum a posteriori (MAP) estimator—multi-scan because it enumerates possible data associations jointly over several scans, and MAP because it seeks the most likely data association conditioned on the observations. This paper extends the TOMHT, building on its internal representation to support probabilistic queries other than MAP estimation. Specifically, by summing over the TOMHT's pruned space of data association hypotheses one c...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

A Markov Chain Channel Model for Active Transport Molecular Communication
In molecular communication, small particles such as molecules are used to convey information. These particles are released by a transmitter into a fluidic environment, where they propagate freely (e.g. through diffusion) or through externals means (e.g. different types of active transport) until they arrive at the receiver. Although there are a number of different mathematical models for the diffusion-based molecular communication, active transport molecular communication (ATMC) lacks the necessary theoretical framework. Previous works had to rely almost entirely on full Monte Carlo simulations of these systems. However, f...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Deepest Minimum Criterion for Biased Affine Estimation
A new strategy called the Deepest Minimum Criterion (DMC) is presented for optimally obtaining an affine transformation of a given unbiased estimator, when a-priori information on the parameters is known. Here, it is considered that the samples are drawn from a distribution parametrized by an unknown deterministic vector parameter. The a-priori information on the true parameter vector is available in the form of a known subset of the parameter space to which the true parameter vector belongs. A closed form exact solution is given for the non-linear DMC problem in which it is known that the true parameter vector belongs to ...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Tracking of Maneuvering Non-Ellipsoidal Extended Object or Target Group Using Random Matrix
For non-ellipsoidal extended object and group target tracking (NEOT and NGTT), using a random matrix to simplify the extension as an ellipsoid, although efficient, may not be accurate enough because of the loss of useful information in shape and orientation. In view of this, we model a non-ellipsoidal extended object or target group as a combination of multiple ellipsoidal sub-objects, each represented by a random matrix. Different sub-objects are distinguished by different dynamic models. Based on such models, a Bayesian approach is proposed to estimate the kinematic states and the extensions of the sub-objects. For maneu...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Adaptive Double Subspace Signal Detection in Gaussian Background—Part II: Partially Homogeneous Environments
In this part of the paper, we continue to study the problem of detecting a double subspace signal in Gaussian noise. Precisely, we address the detection problem in partially homogeneous environments, where the primary and secondary data share the same covariance matrix up to an unknown scaling factor. We derive the generalized likelihood ratio test (GLRT), Rao test, Wald test, and their two-step versions. We also introduce three spectral norm tests (SNTs). All these detectors possess the constant false alarm rate (CFAR) property. Moreover, various kinds of special cases of these detectors are given. At the stage of perform...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

A Bayesian Framework for Blind Adaptive Beamforming
In this work, the problem of blind adaptive beamforming in the presence of steering-vector uncertainty is addressed within a Bayesian estimation framework. We express the single-input multiple-output (SIMO) observation model in the short-time-Fourier-transform (STFT) domain and employ a variational formulation to obtain iterative closed-form learning rules for inferring approximate posteriors on the steering vector and the target signal. By varying the a priori belief in the top-level statistical model, i.e., modeling a quantity as a random process or an unknown deterministic entity, it is shown that the considered framewo...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Reconfigurable Adaptive Array Beamforming by Antenna Selection
Traditional adaptive array beamforming with a fixed array configuration can lead to significant inefficiencies and performance loss under different scenarios. As antennas become smaller and cheaper relative to front-ends, it becomes important to devise a reconfigurable adaptive antenna array (RAAA) strategy to yield high signal to noise and interference ratio using fewer antennas. This is achieved by selecting $K$ from $N$ antennas to minimize the Spatial Correlation Coefficient (SCC) between the desired signal and the interference. The lower bound of optimum SCC is formulated with two relaxation methods to give informatio...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Noncooperative Day-Ahead Bidding Strategies for Demand-Side Expected Cost Minimization With Real-Time Adjustments: A GNEP Approach
The envisioned smart grid aims at improving the interaction between the supply- and the demand-side of the electricity network, creating unprecedented possibilities for optimizing the energy usage at different levels of the grid. In this paper, we propose a distributed demand-side management (DSM) method intended for smart grid users with load prediction capabilities, who possibly employ dispatchable energy generation and storage devices. These users participate in the day-ahead market and are interested in deriving the bidding, production, and storage strategies that jointly minimize their expected monetary expense. The r...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Joint Space Decomposition-and-Synthesis Approach and Achievable DoF Regions for $K$ -User MIMO Interference Channels
The paper proposes a new approach of joint space decomposition-and-synthesis (JSDS) for deriving achievable degree-of-freedom (DoF) region by interference alignment without symbol extension for $K$-user MIMO interference channel. Solving the interference alignment problem is to find the precoders that align desired signal and interference with disjoint subspaces at receivers. A related property of these precoders is that the solution range for each one of them is a union of linear spaces, termed transmit spaces. Based on this property, the JSDS approach is developed to derive transmit spaces that fulfill alignment conditio...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

$L_{1/2}$ Regularization: Convergence of Iterative Half Thresholding Algorithm
In recent studies on sparse modeling, the nonconvex regularization approaches (particularly, $L_{q}$ regularization with $qin(0,1)$ ) have been demonstrated to possess capability of gaining much benefit in sparsity-inducing and efficiency. As compared with the convex regularization approaches (say, $L_{1}$ regularization), however, the convergence issue of the corresponding algorithms are more difficult to tackle. In this paper, we deal with this difficult issue for a specific but typical nonconvex regularization scheme, the $L_{1/2}$ regularization, which has been successfully used to many applications. More specifically,...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

“Quasi-Blind” Calibration of an Array of Acoustic Vector-Sensors That Are Subject to Gain Errors/Mis-Location/Mis-Orientation
This paper advances a new “quasi-blind” calibration algorithm to calibrate a multi-array network (MAN) of acoustic-vector-sensors, whose component-sensors may have non-ideal gain/phase responses, incorrect orientations, and imprecise locations. This proposed calibration is “quasi-blind” in not requiring any prior knowledge/estimation of any training signal's arrival-angle. This proposed algorithm is computationally orders-of-magnitude more efficient than maximum-likelihood estimation. These advantages are achieved here by exploiting the acoustic vector-sensor's quintessential characters, to inte...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Adaptive Double Subspace Signal Detection in Gaussian Background—Part I: Homogeneous Environments
In this two-part paper, we consider the problem of adaptive multidimensional/multichannel signal detection in Gaussian noise with unknown covariance matrix. The test data (primary data) is assumed as a collection of sample vectors, arranged as the columns of a rectangular data array. The rows and columns of the signal matrix are both assumed to lie in known subspaces, but with unknown coordinates. Due to this feature of the signal structure, we name this kind of signal as the double subspace signal. Part I of this paper focuses on the adaptive detection in homogeneous environments, while Part II deals with the adaptive det...
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Table of Contents
(Source: IEEE Transactions on Signal Processing)
Source: IEEE Transactions on Signal Processing - April 11, 2014 Category: Biomedical Engineering Source Type: research

Effects of stent design on new clinical issue of longitudinal stent compression in interventional cardiology.
Abstract In recent years, interventional cardiologists have discussed over a new clinical issue called longitudinal stent compression (LSC), a failure mode not previously observed in coronary stents. This phenomenon occurs when the physician attempts to cross a deployed stent with a second device, causing the stent to dramatically shorten when two devices are accidentally entangled. While this phenomenon has been observed with a number of stent platforms, it seems more common with the Element stent. In this paper, a computational LSC model using finite element analysis was developed. A systematic investigation was ...
Source: Biomedical Microdevices - April 11, 2014 Category: Biomedical Engineering Authors: Hsiao HM, Yeh CT, Wang C, Chao LH, Li DR Tags: Biomed Microdevices Source Type: research

BIT: Biosignal Igniter Toolkit
Abstract: The study of biosignals has had a transforming role in multiple aspects of our society, which go well beyond the health sciences domains to which they were traditionally associated with. While biomedical engineering is a classical discipline where the topic is amply covered, today biosignals are a matter of interest for students, researchers and hobbyists in areas including computer science, informatics, electrical engineering, among others. Regardless of the context, the use of biosignals in experimental activities and practical projects is heavily bounded by the cost, and limited access to adequate support mate...
Source: Computer Methods and Programs in Biomedicine - April 11, 2014 Category: Bioinformatics Authors: Hugo Plácido da Silva, André Lourenço, Ana Fred, Raúl Martins Tags: Section II: Systems and Programs Source Type: research

Between-centre variability in transfer function analysis, a widely used method for linear quantification of the dynamic pressure–flow relation: The CARNet study
The objective of this study was to evaluate between-centre variability in TFA outcome metrics. 15 centres analysed the same 70 BP and CBFV datasets from healthy subjects (n=50 rest; n=20 during hypercapnia); 10 additional datasets were computer-generated. Each centre used their in-house TFA methods; however, certain parameters were specified to reduce a priori between-centre variability. Hypercapnia was used to assess discriminatory performance and synthetic data to evaluate effects of parameter settings. Results were analysed using the Mann–Whitney test and logistic regression. A large non-homogeneous variation was foun...
Source: Medical Engineering and Physics - April 11, 2014 Category: Biomedical Engineering Authors: Aisha S.S. Meel-van den Abeelen, David M. Simpson, Lotte J.Y. Wang, Cornelis H. Slump, Rong Zhang, Takashi Tarumi, Caroline A. Rickards, Stephen Payne, Georgios D. Mitsis, Kyriaki Kostoglou, Vasilis Marmarelis, Dae Shin, Yu-Chieh Tzeng, Philip N. Ainslie, Tags: Papers Source Type: research

CDRH OSEL Recruitment for ORISE - Postdoctoral Fellowship (Biomedical Engineer)
(Source: Food and Drug Adminstration (FDA): CDRHNew)
Source: Food and Drug Adminstration (FDA): CDRHNew - April 10, 2014 Category: Medical Equipment Source Type: news

Controlled ultrasonic micro-dissection of thin tissue sections.
Abstract In order to obtain sufficient quantities of pure populations of cells or a single cell from surrounding tissue for analytical investigation, we have developed an ultrasonic microdissection system. The system utilizes a vision-based method for detecting the contact between the microdissection needle tip and a target surface. A multilayer stack piezoelectric actuator is employed to generate ultrasonic vibrations for histological isolation. Automated micro-dissection is also realized using visual feedback and vision-based control. Experimental results on tumor tissue sections show that the system has a high d...
Source: Biomedical Microdevices - April 10, 2014 Category: Biomedical Engineering Authors: Ru C, Liu J, Pang M, Sun Y Tags: Biomed Microdevices Source Type: research

Mixotrophic cultivation of oleaginous Chlorella sp. KR-1 mediated by actual coal-fired flue gas for biodiesel production.
Abstract Flue gases mainly consist of CO2 that can be utilized to facilitate microalgal culture for bioenergy production. In the present study, to evaluate the feasibility of the utilization of flue gas from a coal-burning power plant, an indigenous and high-CO2-tolerant oleaginous microalga, Chlorella sp. KR-1, was cultivated under mixotrophic conditions, and the results were evaluated. When the culture was mediated by flue gas, highest biomass (0.8 g cells/L·d) and FAME (fatty acid methyl esters) productivity (121 mg/L·d) were achieved in the mixotrophic mode with 5 g/L glucose, 5 mM nitrate, and a flow rat...
Source: Bioprocess and Biosystems Engineering - April 10, 2014 Category: Biomedical Engineering Authors: Praveenkumar R, Kim B, Choi E, Lee K, Cho S, Hyun JS, Park JY, Lee YC, Lee HU, Lee JS, Oh YK Tags: Bioprocess Biosyst Eng Source Type: research

Modeling Pressure Drop Using Generalized Scaffold Characteristics in an Axial-Flow Bioreactor for Soft Tissue Regeneration.
Abstract The goal of this study was to better understand how analytical permeability models based on scaffold architecture can facilitate a non-invasive technique to real time monitoring of pressure drop in bioreactors. In particular, we evaluated the permeability equations for electrospun and freeze dried scaffolds via pressure drop comparison in an axial-flow bioreactor using computational fluid dynamic (CFD) and experimentation. The polycaprolactone-cellulose acetate fibers obtained by co-axial electrospinning technique and Chitosan-Gelatin scaffolds prepared using freeze-drying techniques were utilized. Initial...
Source: Annals of Biomedical Engineering - April 10, 2014 Category: Biomedical Engineering Authors: Podichetty JT, Bhaskar PR, Khalf A, Madihally SV Tags: Ann Biomed Eng Source Type: research

An In Vitro Evaluation of the Impact of Eccentric Deployment on Transcatheter Aortic Valve Hemodynamics.
The objective of this study is to evaluate whether eccentric deployment of TAVRs lead to turbulent blood flow and blood cell damage. Particle Image Velocimetry was used to quantitatively characterize fluid velocity fields, shear stress and turbulent kinetic energy downstream of TAVRs deployed in circular and eccentric orifices representative of deployed TAVRs in vivo. Effective orifice area (EOA) and mean transvalvular pressure gradient (TVG) values did not differ substantially in circular and eccentric deployed valves, with only a minor decrease in EOA observed in the eccentric valve (2.0 cm(2) for circular, 1.9 cm(2) f...
Source: Annals of Biomedical Engineering - April 10, 2014 Category: Biomedical Engineering Authors: Gunning PS, Saikrishnan N, McNamara LM, Yoganathan AP Tags: Ann Biomed Eng Source Type: research

Validation of Algorithms for the Estimation of Pulse Transit Time: Where do We Stand Today?
PMID: 24719049 [PubMed - as supplied by publisher] (Source: Annals of Biomedical Engineering)
Source: Annals of Biomedical Engineering - April 10, 2014 Category: Biomedical Engineering Authors: Papaioannou TG, Vardoulis O, Stergiopulos N Tags: Ann Biomed Eng Source Type: research

Pro-Atherogenic Shear Stress and HIV Proteins Synergistically Upregulate Cathepsin K in Endothelial Cells.
Abstract Major advances in highly active antiretroviral therapies (HAART) have extended the lives of people living with HIV, but there still remains an increased risk of death by cardiovascular diseases (CVD). HIV proteins have been shown to contribute to cardiovascular dysfunction with effects on the different cell types that comprise the arterial wall. In particular, HIV-1 transactivating factor (Tat) has been shown to bind to endothelial cells inducing a range of responses that contribute to vascular dysfunction. It is well established that hemodynamics also play an important role in endothelial cell mediated at...
Source: Annals of Biomedical Engineering - April 10, 2014 Category: Biomedical Engineering Authors: Parker IK, Roberts LM, Hansen L, Gleason RL, Sutliff RL, Platt MO Tags: Ann Biomed Eng Source Type: research

Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow
The objective of this review was to provide an overview of transfer function techniques used in the assessment of CA.113 publications were included. This literature showed that there is no gold standard for the execution and implementation of the transfer function. There is a high diversity in settings and criteria used for transfer function analysis. Notable is also the high number of studies which report little on the settings.This disparity makes it difficult to replicate or compare the results of the different studies and further hinders the opportunity to make a distinction between intact and impaired CA in different ...
Source: Medical Engineering and Physics - April 10, 2014 Category: Biomedical Engineering Authors: Aisha S.S. Meel-van den Abeelen, Arenda H.E.A. van Beek, Cornelis H. Slump, Ronney B. Panerai, Jurgen A.H.R. Claassen Tags: Review Source Type: research

The effect of signal acquisition and processing choices on ApEn values: Towards a “gold standard” for distinguishing effort levels from isometric force records
This study determined the effect of sampling and parameter choices by examining changes in ApEn values across a range of submaximal isometric contractions of the first dorsal interosseus. Reducing the sample rate by decimation changed both the value and pattern of ApEn values dramatically. The pattern of ApEn values across the range of effort levels was not sensitive to the filter cut-off frequency, or the criterion used to extract the section of data for analysis. The complexity increased with increasing effort levels using a fixed ‘r’ value (which accounts for measurement noise) but decreased with increasing effort l...
Source: Medical Engineering and Physics - April 10, 2014 Category: Biomedical Engineering Authors: Sarah M. Forrest, John H. Challis, Samantha L. Winter Tags: Papers Source Type: research