MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Medical Engineering and Physics' source. Tue, 07 Feb 2012 07:42:49 +0100 http://www.medworm.com/index.php?rid=5595018&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311003377%2Fabstract%3Frss%3Dyes As this is my first editorial as Editor-in-Chief of your journal I offer the following words by way of introduction. I am a biomedical engineer with a background in Haemodynamics, Biomaterials and Tissue Engineering. I graduated from the University of Edinburgh with a Bachelor’s degree in Engineering Science, and gained my PhD at the University of Liverpool, where I was lecturer in Medical Device Design. In 2007 I joined the Department of Bioengineering at Strathclyde, where I am currently Course Director of the UK Engineering and Physical Sciences Research Council’s Doctoral Training Centre in Medical Devices. I have been a member of the Institute of Physics and Engineering in Medicine since its formation therefore I am honoured to become editor of Medical Engineering and Physics, one... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595018 Sun, 01 Jan 2012 05:00:00 +0100 5595018 http://www.medworm.com/index.php?rid=5595017&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311003389%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595017 Sun, 01 Jan 2012 05:00:00 +0100 5595017 http://www.medworm.com/index.php?rid=5405180&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311002839%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405180 Mon, 14 Nov 2011 23:47:03 +0100 5405180 http://www.medworm.com/index.php?rid=5595031&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331100155X%2Fabstract%3Frss%3Dyes This study demonstrates that for a hole smaller than this size, optical motion capture with a cluster-based multi-segment foot model is feasible for measure foot in shoe kinematics in vivo. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595031 Mon, 05 Sep 2011 04:00:00 +0100 5595031 http://www.medworm.com/index.php?rid=5158156&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311002049%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158156 Fri, 26 Aug 2011 13:04:58 +0100 5158156 http://www.medworm.com/index.php?rid=5595030&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001615%2Fabstract%3Frss%3Dyes Abstract: Heart rate variability (HRV) is used as a marker of autonomic modulation of heart rate. Nonlinear HRV parameters providing information about the scaling behaviour or the complexity of the cardiac system were included. In addition, the chaotic behaviour was quantified by means of the recently developed numerical noise titration technique. 24h Holter recordings of a large healthy population (N=276, 141 males, 18–71 years of age) were available. The goal was to investigate the influence of gender, age and day–night variation on these nonlinear HRV parameters. Numerical titration yielded similar information as other nonlinear HRV parameters do. However, it does not require long and cleaned data and therefore applicable on short (5min) noisy time series. A higher nonlinear behavio... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595030 Thu, 18 Aug 2011 04:00:00 +0100 5595030 http://www.medworm.com/index.php?rid=5103224&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001731%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5103224 Sun, 07 Aug 2011 08:55:27 +0100 5103224 http://www.medworm.com/index.php?rid=5595028&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001597%2Fabstract%3Frss%3Dyes This study proposes an advanced finite element (FE) head modeling technique through which high-resolution FE meshes adaptive to the degree of tissue anisotropy can be generated. Our adaptive meshing scheme (called wMesh) uses MRI structural information and fractional anisotropy maps derived from diffusion tensors in the FE mesh generation process, optimally reflecting electrical properties of the human brain. We examined the characteristics of the wMeshes through various qualitative and quantitative comparisons to the conventional FE regular-sized meshes that are non-adaptive to the degree of white matter anisotropy. We investigated numerical differences in the FE forward solutions that include the electrical potential and current density generated by current sources in the brain. The quan... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595028 Fri, 05 Aug 2011 04:00:00 +0100 5595028 http://www.medworm.com/index.php?rid=5595029&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001603%2Fabstract%3Frss%3Dyes Abstract: Phase space reconstruction, which is performed by converting echocardiogram-derived strain data from different ventricular regions into phase space trajectories, is applied in this study to describe nonlinear behaviour of myocardial coordination. A new method was developed to quantify patterns of phase space trajectories. Echocardiograms of 31 healthy individuals and 63 patients with left bundle branch block (LBBB) and different left ventricular ejection fractions (LVEFs) were used to evaluate this method. The LBBB patients were separated into two groups: LBBB with a LVEF≥50% and LBBB with a LVEF (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595029 Thu, 04 Aug 2011 04:00:00 +0100 5595029 http://www.medworm.com/index.php?rid=5595026&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001573%2Fabstract%3Frss%3Dyes Abstract: Prostate brachytherapy guided by transrectal ultrasound is a common treatment option for early stage prostate cancer. Prostate cancer accounts for 28% of cancer cases and 11% of cancer deaths in men with 217,730 estimated new cases and 32,050 estimated deaths in 2010 in the United States alone. The major current limitation is the inability to reliably localize implanted radiation seeds spatially in relation to the prostate. Multimodality approaches that incorporate X-ray for seed localization have been proposed, but they require both accurate tracking of the imaging device and segmentation of the seeds. Some use image-based radiographic fiducials to track the X-ray device, but manual intervention is needed to select proper regions of interest for segmenting both the tracking fidu... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595026 Mon, 01 Aug 2011 04:00:00 +0100 5595026 http://www.medworm.com/index.php?rid=5405188&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001275%2Fabstract%3Frss%3Dyes Abstract: This paper presents a new thermal model for bone drilling with applications to orthopaedic surgery. The new model combines a unique heat-balance equation for the system of the drill bit and the chip stream, an ordinary heat diffusion equation for the bone, and heat generation at the drill tip, arising from the cutting process and friction. Modeling of the drill bit-chip stream system assumes an axial temperature distribution and a lumped heat capacity effect in the transverse cross-section. The new model is solved numerically using a tailor-made finite-difference scheme for the drill bit-chip stream system, coupled with a classic finite-difference method for the bone. The theoretical investigation addresses the significance of heat transfer between the drill bit and the bone, hea... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405188 Mon, 01 Aug 2011 04:00:00 +0100 5405188 http://www.medworm.com/index.php?rid=5595027&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001585%2Fabstract%3Frss%3Dyes Abstract: Objective: To investigate the influence of exercise conditions (speed and method to impose power) on the applied force, force effectiveness and distribution of work during handcycling.Method: Ten able-bodied men performed handcycling on a treadmill. To test the effect of speed, subjects propelled at different velocities (1.38m/s, 1.66m/s, 1.94m/s) with a constant power output (35W). To test the effect of method to impose power, subjects cycled at a constant speed (1.66m/s) and different power outputs imposed by incline (1%, 2.5%, 4%) versus pulley system (simulated resistance of incline conditions). From the applied forces, fraction of effective force and work production over the propulsion cycle were calculated.Results: While total force (24.2 to 18.2N) and tangential force (20.... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595027 Thu, 28 Jul 2011 04:00:00 +0100 5595027 http://www.medworm.com/index.php?rid=5595025&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001561%2Fabstract%3Frss%3Dyes Abstract: For the development of articular cartilage replacement material, it is essential to study the dependence between mechanical stimulation and cell activity in cellular specimens. Bioreactor cultivation is widely used for this purpose, however, it is hardly possible to obtain a quantitative relationship between collagen type II production and applied loading history. For this reason, a bioreactor system is developed, measuring applied forces and number of loading cycles by means of a load cell and a forked light barrier, respectively. Parallel to the experimental study, a numerical model by means of the finite element method is proposed to simulate the evolution of material properties during cyclic stimulation. In this way, a numerical model can be developed for arbitrary deformatio... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595025 Tue, 26 Jul 2011 04:00:00 +0100 5595025 http://www.medworm.com/index.php?rid=5595019&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001470%2Fabstract%3Frss%3Dyes Abstract: The incidence of osteoporosis continues to increase with progressively aging populations. The purpose of this study was to detect the effects of glucocorticoid (GC) treatment on bone mineral density (BMD), biomechanical strength and micro-architecture in cancellous and cortical bone in ovariectomized (OVX) rabbits. Twenty adult female New Zealand white rabbits were randomly divided into three groups. The OVX-GC group (n=8) received a bilateral ovariectomy first and then daily GC treatment (methylprednisolone sodium succinate, 1mg/kg/day) for 4 weeks beginning 2 weeks after ovariectomy treatment. The OVX group (n=4) received a bilateral ovariectomy without GC treatment. The sham group (n=8) only received the sham operation. BMD was determined prior to and 6 weeks after the operati... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595019 Wed, 20 Jul 2011 04:00:00 +0100 5595019 http://www.medworm.com/index.php?rid=5595032&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001536%2Fabstract%3Frss%3Dyes Abstract: In this paper we investigate blood flow in the ophthalmic artery (OA) which is the major artery supplying blood to the eyes. An OA and several other cerebral arteries are digitized from a computed tomography angiography (CTA) image of an aneurysm patient. Utilizing a reduced version (1D) of the governing Navier–Stokes equations we solve the transient flow in these arteries. The flow waveform of the patient–OA is compared with that in a healthy vascular tree, and also with published ultrasonic measurements. We found that hyperemia rather than ischemia occurred in the OA, and we suggest that this was unlikely to be the cause of impaired vision in the patient. A more likely explanation is the compression of the optic nerves caused by the mass of the aneurysm. (Source: Medical En... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595032 Mon, 18 Jul 2011 04:00:00 +0100 5595032 http://www.medworm.com/index.php?rid=5595024&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001548%2Fabstract%3Frss%3Dyes The objective of this study was to investigate the control algorithm in both experiment and simulation. We tested reactions on a slip with different fixed increases in stimulator command and an algorithm with adaptive increase in stimulator command based on the amplitude of the processed nerve signal. Further, the application of a number of maximum stimulator commands with double the instantaneous stimulation frequency as an initial reaction to a slip was investigated. We tested three different surfaces of the held object, representing different frictional conditions of the skin-object contact. A discussion of the slip-based controller concludes the paper. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595024 Mon, 18 Jul 2011 04:00:00 +0100 5595024 http://www.medworm.com/index.php?rid=5595023&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001524%2Fabstract%3Frss%3Dyes Abstract: The finite element analysis (FEA) has been identified as a useful tool for the stress and strain behaviour determination in lower limb prosthetics. The residual limb and prosthetic socket interface was the main subject of interest in previous studies. This paper focuses on the finite element analysis for the evaluation of structural behaviour of the Sure-flex™ prosthetic foot and other load-bearing components. A prosthetic socket was not included in the FEA. An approach for the finite element modelling including foot analysis, reverse engineering and material property testing was used. The foot analysis incorporated ground reaction forces measurement, motion analysis and strain gauge analysis. For the material model determination, non-destructive laboratory testing and its FE s... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595023 Mon, 18 Jul 2011 04:00:00 +0100 5595023 http://www.medworm.com/index.php?rid=5595022&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001512%2Fabstract%3Frss%3Dyes Abstract: In this paper, we present a novel decentralized robust methodology for control of quiet upright posture during arm-free paraplegic standing using functional electrical stimulation (FES). Each muscle–joint complex is considered as a subsystem and individual controllers are designed for each one. Each controller operates solely on its associated subsystem, with no exchange of information between them, and the interaction between the subsystems are taken as external disturbances. In order to achieve robustness with respect to external disturbances, unmodeled dynamics, model uncertainty and time-varying properties of muscle–joint dynamics, a robust control framework is proposed. The method is based on the synergistic combination of an adaptive nonlinear compensator with sliding m... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595022 Mon, 18 Jul 2011 04:00:00 +0100 5595022 http://www.medworm.com/index.php?rid=5595021&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001494%2Fabstract%3Frss%3Dyes In this study, computational fluid dynamics was applied to in vivo data to provide quantitative insight into the hemodynamic response of the deep venous system to static external compression. The geometry and flow information of deep veins before and after compression was acquired from ten healthy volunteers using magnetic resonance imaging.Our results indicated that application of the compression stocking led to a small reduction in blood flow rate but a significant reduction in cross-sectional area of the peroneal veins in the calf, resulting in an increase in wall shear stress (WSS), but the individual effects were highly variable. The mean volume reduction of the deep veins was 58%, while the time-averaged WSS showed an average increase of 398% after compression (median 98%). The analy... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595021 Mon, 18 Jul 2011 04:00:00 +0100 5595021 http://www.medworm.com/index.php?rid=5405196&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001457%2Fabstract%3Frss%3Dyes In conclusion, our findings did not support the idea that JLE is a major contributor to midflexion instability for this particular ultra-congruent implant design. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405196 Mon, 18 Jul 2011 04:00:00 +0100 5405196 http://www.medworm.com/index.php?rid=5405195&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001469%2Fabstract%3Frss%3Dyes This study presents a new method of vertebra tracking, based on image template matching of the contour of the vertebral body for an accurate intervertebral kinematics analysis. An image gradient operator was utilized to obtain the vertebral contours; it operates after an edge-preserving smoothing filter designed to reduce low dose X-ray image noise. Once a template is defined for each vertebra, this is used to determine the best vertebral location in each image throughout the fluoroscopic sequence. Accuracy of the proposed method was tested using images of a calibration model. Average error achieved for the intervertebral angle is of the order of 0.4° and approximately 2mm for the intervertebral centre of rotation. Five fluoroscopic lumbar sequences of healthy volunteers undergoing passiv... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405195 Mon, 18 Jul 2011 04:00:00 +0100 5405195 http://www.medworm.com/index.php?rid=5405192&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001305%2Fabstract%3Frss%3Dyes This study presents a new method for the 3D reconstruction of the human cranial vault from routine Computed Tomography (CT) data. The reconstruction method was based on the conceptualization of the shape of the cranial vault with a parametric description. An initialization was first realized with the identification of anatomical landmarks and contours on Digitally Reconstructed Radiographs (DRR) in order to obtain a pre-personalized reconstruction. Then an optimization of the reconstruction was performed to segment the internal and external surfaces of the cranial vault for thickness computation. The method was validated by comparing final reconstructions issued from our approach and from a manual slice-by-slice segmentation method on ten CT-scans. Errors were comparable to the CT image re... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405192 Mon, 18 Jul 2011 04:00:00 +0100 5405192 http://www.medworm.com/index.php?rid=5595020&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001482%2Fabstract%3Frss%3Dyes Abstract: A model has been developed to definitively characterize the resistance properties and the joint loading (i.e., shear and compressive components of the joint reaction force) in single-joint exercises with ideal elastic bands. The model accounts for the relevant geometric and elastic properties of the band, the band pre-stretching, and the relative positioning among the joint center of rotation and the fixation points of the band. All the possible elastic torque profiles of ascending–descending, descending, or ascending type were disclosed in relation to the different ranges of joint angles. From these results the elastic resistance setting that best reproduces the average-user's knee extensor torque in maximal isometric/isokinetic efforts was determined. In this optimized settin... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5595020 Fri, 15 Jul 2011 04:00:00 +0100 5595020 http://www.medworm.com/index.php?rid=5405199&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001445%2Fabstract%3Frss%3Dyes In this study, we propose a robust procedure for structured mesh generation, tailoring the mesh structure to the subject-specific vessel topology. The proposed methodology is based on centerline-based synthetic descriptors (i.e. centerlines, radii and centerlines’ normals) which are used to solve the meshing problem following a bottom-up approach. First, topologically equivalent block-structures are placed inside and outside the lumen domain. Then, a projection operation is performed, returning a parametric volume mesh which fits the original triangulated model with sub-micrometric accuracy. Additionally, a three-layered arterial wall (resembling the intima, media and adventitia) is artificially generated, with the possibility of setting variable thickness (e.g. proximal-to-distal taperi... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405199 Fri, 15 Jul 2011 04:00:00 +0100 5405199 http://www.medworm.com/index.php?rid=5405184&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001238%2Fabstract%3Frss%3Dyes Highlights: ► We geometrically revised an epiphyseal hip prosthesis using finite element models. ► High stresses in the prototype implant promoted failure after implantation. ► Revision reduced the implant stresses while ensuring the implant stability. ► Numerical findings were corroborated by destructive tests before and after revision. ► The new device is a potential alternative to current hip epiphyseal devices.Abstract: An innovative epiphyseal device has been recently proposed claiming an effective bone–prosthesis load transfer and a nearly physiological bone stresses distribution. However preliminary experimental tests showed a 23% weakening of the femoral neck after implantation. Aim of this study was to revise the prosthesis geometry with the goal of enhancing the femor... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405184 Fri, 15 Jul 2011 04:00:00 +0100 5405184 http://www.medworm.com/index.php?rid=5405194&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001433%2Fabstract%3Frss%3Dyes Abstract: This paper presents a 3D finite element upper arm model, validated by experiments as well as clinical data, used to study the error introduced in blood pressure measurements due to variability of arm tissue mechanical properties. The model consists of three separate cylindrical parts: soft tissue, bone and brachial artery. The artery volume changes under the cuff are used to represent the cuff pressure oscillations for analyzing blood pressure measurements. These oscillation trends are identical to observed clinical data. Also an upper arm simulator is designed and built for model validation. The model shows that the variation of soft tissue compressibility introduces an error up to 5% in blood pressure measurements. It is also revealed that the variation of the brachial artery a... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405194 Wed, 13 Jul 2011 04:00:00 +0100 5405194 http://www.medworm.com/index.php?rid=5405193&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001329%2Fabstract%3Frss%3Dyes Abstract: Image quality assessment is required for an optimal use of mammographic units. On the one hand, there are objective image quality assessment methods based on the measurement of technical parameters such as modulation transfer function (MTF), noise power spectrum (NPS) or detection quantum efficiency (DQE) describing performances of digital detectors. These parameters are, however, without direct relationship with lesion detectability in clinical practice. On the other hand, there are image quality assessment methods involving time consuming procedures, but presenting a direct relationship with lesion detectability. This contribution describes an X-ray source/digital detector model leading to the simulation of virtual contrast-detail phantom (CDMAM) images. The virtual image compu... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405193 Mon, 11 Jul 2011 04:00:00 +0100 5405193 http://www.medworm.com/index.php?rid=5405191&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001317%2Fabstract%3Frss%3Dyes Abstract: Multiple mouse models have been developed to increase our understanding of the natural history of abdominal aortic aneurysms. An advantage of such models is that one can quantify the time course of changes in geometry, histology, cell biology, and mechanics as a lesion develops. One of the most commonly used mouse models yields lesions in the suprarenal abdominal aorta whereas most other models target the infrarenal abdominal aorta, consistent with the clinical observation that nearly all abdominal aneurysms in humans occur in the infrarenal aorta. Understanding reasons for similarities and differences between diverse mouse models and human lesions may provide increased insight that would not be possible studying a single situation alone. Toward this end, however, we must first c... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405191 Mon, 11 Jul 2011 04:00:00 +0100 5405191 http://www.medworm.com/index.php?rid=5405198&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001330%2Fabstract%3Frss%3Dyes Abstract: This paper describes a non-invasive human brain-actuated robotic arm experiment, which allows remote writing. In the local environment, the participant decides on an arbitrary word to transmit. A mental speller interface is then used to select the letters. A robot arm placed in the remote environment writes the word on a whiteboard in real time. A multidisciplinary framework such as the one presented here exemplifies a class of interactive applications with possible relevance in a variety of fields, such as entertainment and clinical environments. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405198 Fri, 08 Jul 2011 04:00:00 +0100 5405198 http://www.medworm.com/index.php?rid=5405181&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001202%2Fabstract%3Frss%3Dyes This study attempted to lower strains by altering the orthogonal geometry and avoiding extended vertical saw cuts. Finite element models were utilized to predict biomechanical behavior and were subsequently compared against experimental data. On the resected surface of the extended saw cut model, the greatest strains showed a 50% increase over a standard implant; conversely, the strains decreased by 40% for the radial-corner shaped model. For all UKA models, the peak strains below the resection level increased by 40% relative to an intact tibia. There was no significant difference among the implanted models. This study demonstrated that a large increase in strains arises on the tibial plateau to resist a cantilever-like bending moment following UKA. Surgical errors generally weaken the tib... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405181 Fri, 08 Jul 2011 04:00:00 +0100 5405181 http://www.medworm.com/index.php?rid=5405190&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001299%2Fabstract%3Frss%3Dyes Abstract: In this paper a self-opening intrafascicular neural interface (SELINE) has been modeled using both a theoretical approach and a Finite Element (FE) analysis. This innovative self opening interface has several potential advantages such as: higher selectivity due to its three-dimensional structure and efficient anchorage system. Mechanical, structural and micro-technological issues have been considered to obtain an effective design of the electrode, as a feasibility study of the self-opening approach. A simple framework has been provided to model the insertion and partial retraction into peripheral nerves, resulting in the opening of wings.This integrated approach results in a rational procedure to optimize kinematics, geometry, and structural properties of peripheral interfaces. T... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405190 Thu, 30 Jun 2011 04:00:00 +0100 5405190 http://www.medworm.com/index.php?rid=5405185&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331100124X%2Fabstract%3Frss%3Dyes Highlights: ► Analysis of 4 metal-on-metal hip resurfacing patients with known metal ion levels. ► Activity patterns (gait & stairs), published hip forces and FEA were combined. ► Steeply inclined acetabular components edge-load: Contact stress increase is ≥50%. ► High metal ion levels result from inclination angle influenced edge-loading. ► Individuals activity patterns can reduce the effects of steep acetabular components.Abstract: The occurrence of pseudotumours (soft tissue masses relating to the hip joint) following metal-on-metal hip resurfacing arthroplasty (MoMHRA) has been associated with high serum metal ion levels and consequently higher than normal bearing wear. We investigated the relationship between serum metal ion levels and contact stress on the acetabular comp... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405185 Mon, 27 Jun 2011 04:00:00 +0100 5405185 http://www.medworm.com/index.php?rid=4968178&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001354%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968178 Sun, 26 Jun 2011 19:54:05 +0100 4968178 http://www.medworm.com/index.php?rid=5405197&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001226%2Fabstract%3Frss%3Dyes This study examined the absolute differences in neutral positions of the joints of the foot with different footwear. This addresses the question of whether separate static trials should be collected for each footwear condition to establish neutral positions.Methods: A multi-segment kinematic foot model and optical motion analysis system measured four inter-segmental joints of the foot: (1) hindfoot-to-midfoot in the frontal plane, (2) forefoot-to-midfoot in the frontal plane, (3) hallux-to-forefoot in the sagittal plane, and (4) the height-to-length ratio of the medial longitudinal arch. Barefoot was compared to three shoe condition using Nike Free trainers of varying longitudinal torsional stiffness in ten male volunteers.Findings: There was high variability both within subjects and shoe ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405197 Thu, 23 Jun 2011 04:00:00 +0100 5405197 http://www.medworm.com/index.php?rid=5405186&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001263%2Fabstract%3Frss%3Dyes Abstract: Orthopaedic drilling operations without optimum operating parameters by surgeons may cause bone defects such as bone fracture, cracks, osteolysis and tissue loss around the drilling zone. For the sake of optimum drilling parameters, an in vitro study was performed by considering the bone mineral density, bone sex, drill tip angle, drill speed, drill force and feed-rate. The specimens were taken from the drilled sites of fresh male and female calf tibias. The temperature changes at the drill site were investigated throughout the statistical and histopathological analysis. It was observed that the temperature increased with an increasing drill speed and decreased with high feed-rates and applied drill forces. The drilling temperatures of the female bovine tibias were found to be hi... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405186 Thu, 23 Jun 2011 04:00:00 +0100 5405186 http://www.medworm.com/index.php?rid=5405189&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001287%2Fabstract%3Frss%3Dyes In conclusion, the present stiffness meter may be used to quantify in vivo mechanical properties of soft tissues in the forearm, sensitively modulated by soft tissue swelling and muscle loading. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405189 Wed, 22 Jun 2011 04:00:00 +0100 5405189 http://www.medworm.com/index.php?rid=5332780&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000944%2Fabstract%3Frss%3Dyes Abstract: Non-invasive quantification of bone shape is crucial in orthopaedic research. The primary objective of this study was to develop an automated statistical morphometry method for comparing the cross-sectional images of normal and diseased bones. The secondary objective involved demonstrating the effectiveness of the proposed method in distinguishing AIS patients from normal controls. This framework is composed of bone segmentation followed by measurements of maximum and minimum bone diameters, inter-group and intra-group statistical morphometry, and statistical analysis of bone thickness. The proposed framework was applied to detect bone morphological abnormality in adolescent idiopathic scoliosis (AIS) patients. The forearm bones in cross-sectional peripheral quantitative computed... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332780 Wed, 22 Jun 2011 04:00:00 +0100 5332780 http://www.medworm.com/index.php?rid=5405183&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001214%2Fabstract%3Frss%3Dyes Abstract: Background: Historically, single port valveless pneumatic blood pumps have had a high incidence of thrombus formation due to areas of blood stagnation and hemolysis due to areas of high shear stress.Methods: To ensure minimal hemolysis and favorable blood washing characteristics, particle image velocimetry (PIV) and computational fluid dynamics (CFD) were used to evaluate the design of a new single port, valveless counterpulsation device (Symphony). The Symphony design was tested in 6-h acute (n=8), 5-day (n=8) and 30-day (n=2) chronic experiments in a calf model (Jersey, 76kg). Venous blood samples were collected during acute (hourly) and chronic (weekly) time courses to analyze for temporal changes in biochemical markers and quantify plasma free hemoglobin. At the end of the st... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405183 Fri, 17 Jun 2011 04:00:00 +0100 5405183 http://www.medworm.com/index.php?rid=5405187&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001251%2Fabstract%3Frss%3Dyes In this study, the FE model of foot and ankle was validated during balance standing. There was a good agreement in the overall patterns of predicted and measured plantar pressure distribution published in literature. The coupled foot–boot model will be fully validated in the subsequent works under both static and dynamic loading conditions for further studies on injuries investigation in military and sports, foot wear design and characteristics of parachute landing impact in military. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405187 Wed, 15 Jun 2011 04:00:00 +0100 5405187 http://www.medworm.com/index.php?rid=5332785&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001172%2Fabstract%3Frss%3Dyes This study demonstrated that a cervical spine model can be developed at the tissue level and provide accurate biofidelic kinematic and local tissue response, leading to injury prediction in automotive crash scenarios. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332785 Mon, 13 Jun 2011 04:00:00 +0100 5332785 http://www.medworm.com/index.php?rid=5332772&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000919%2Fabstract%3Frss%3Dyes Abstract: Given the limited availability of donor hearts, ventricular assist device (VAD) therapy is fast becoming an accepted alternative treatment strategy to treat end-stage heart failure. The field of mechanical ventricular assistance is littered with novel and unique ideas either based on volume displacement or rotary pump technology, which aim to sufficiently restore cardiac output. However, only a select few have made the transition to the clinical arena.Clinical implants were initially dominated by the FDA approved volume displacement Thoratec HeartMate I, IVAD, and PVAD, whilst Berlin Heart's EXCOR, and Abiomed's BVS5000 and AB5000 offered suitable alternatives. However, limitations associated with an inherently large size and reduced lifetime of these devices stimulated the devel... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332772 Mon, 13 Jun 2011 04:00:00 +0100 5332772 http://www.medworm.com/index.php?rid=5405182&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001196%2Fabstract%3Frss%3Dyes Abstract: In some cases of aortic valve leaflet disease, the implant of a stentless biological prosthesis represents an excellent option for aortic valve replacement (AVR). In particular, if compared to more classical surgical approaches, it provides a more physiological hemodynamic performance and a minor trombogeneticity avoiding the use of anticoagulants. The clinical outcomes of AVR are strongly dependent on an appropriate choice of both prosthesis size and replacement technique, which are, at present, strictly related to surgeon's experience and skill. Therefore, also this treatment, like most reconstructive procedures in cardiac surgery, remains “more art than science” . Nowadays computational methodologies represent a useful tool both to investigate the aortic valve behavior, in... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5405182 Fri, 10 Jun 2011 04:00:00 +0100 5405182 http://www.medworm.com/index.php?rid=5332784&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001184%2Fabstract%3Frss%3Dyes Abstract: The anterior tympanomeatal angle (ATA) blunting is clinically defined as a certain degree of the ATA obliteration due to excessive fibrous tissue formation, which is a relatively common complication of external auditory canal (EAC) related operations. The aim of this study was to examine the effect of ATA blunting on the middle ear transfer function using a finite element (FE) model. Results showed that the displacements at the tympanic membrane (TM), at the manubrium and at the stapes footplate, and also the ratio of stapes footplate velocity to the sound pressure in the EAC were decreased to various degrees from ATA blunting of Grades 1–4. This was more significant with TM thickening at the frequencies below 3.2kHz, particularly in Grades 3 and 4 when analyzing the anterior r... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332784 Fri, 10 Jun 2011 04:00:00 +0100 5332784 http://www.medworm.com/index.php?rid=5332782&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001123%2Fabstract%3Frss%3Dyes Conclusion: There is shown to be increased value of LV Ees and a more favorable decreased value of AVM index in those IDCM patients who underwent SVR. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332782 Mon, 06 Jun 2011 04:00:00 +0100 5332782 http://www.medworm.com/index.php?rid=5332787&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001093%2Fabstract%3Frss%3Dyes Conclusion: This is the first instrumented handbike system that can register 3-dimensional forces. It can be concluded that the instrumented handbike system allows for an accurate force analysis based on forces registered at the handle bars. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332787 Thu, 02 Jun 2011 04:00:00 +0100 5332787 http://www.medworm.com/index.php?rid=5332783&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001111%2Fabstract%3Frss%3Dyes Abstract: Accelerometer-based activity monitoring sensors have become the most suitable means for objective assessment of mobility trends within patient study groups. The use of minimal, low power, IC (integrated circuit) components within these sensors enable continuous (long-term) monitoring which provides more accurate mobility trends (over days or weeks), reduced cost, longer battery life, reduced size and weight of sensor. Using scripted activities of daily living (ADL) such as sitting, standing, walking, and numerous postural transitions performed under supervised conditions by young and elderly subjects, the ability to discriminate these ADL were investigated using a single tri-axial accelerometer, mounted on the trunk. Data analysis was performed using Matlab® to determine the acc... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332783 Thu, 02 Jun 2011 04:00:00 +0100 5332783 http://www.medworm.com/index.php?rid=5332781&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331100110X%2Fabstract%3Frss%3Dyes Abstract: When ultrasound imaging is used for breast cancer diagnosis, the lesion's morphology is usually used to determine if the lesion is benign or malignant. Sometimes, the information provided by the procedure may not be adequate to make an accurate judgment. Additional information is needed, such as the stiffness of the lesion relative to its surrounding tissue. This paper presents an ultrasound accessory device designed to achieve this purpose. The device is easy to operate and is similar in use to a normal clinical breast ultrasound examination. A sonologist must only attach an ultrasound probe to the device and then slide it across the lesion maintaining a constant compression depth. The built-in inverse biomechanical model of the device will then calculate the predicted stiffness... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332781 Mon, 30 May 2011 04:00:00 +0100 5332781 http://www.medworm.com/index.php?rid=5332777&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331100097X%2Fabstract%3Frss%3Dyes This study compared the effects of monopolar and bipolar electrode configurations on interference pattern analysis of the surface electromyographic (sEMG). Twenty-four college-aged male participants performed isometric actions of the elbow flexors at 40, 60, 80, and 100 percent of maximal voluntary contraction (MVC). Separate (Ag/AgCl) electrodes were used for both configurations. There were five measures associated with “spike shape” analysis: mean spike amplitude (MSA), mean spike frequency (MSF), mean spike slope (MSS), mean spike duration (MSD) and mean number of peaks per spike (MNPPS). A load-cell and wrist-cuff assembly was used to record isometric elbow flexion forces. Both electrode configurations resulted in the same trends force changes in spike shape measures across force l... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332777 Mon, 30 May 2011 04:00:00 +0100 5332777 http://www.medworm.com/index.php?rid=5332774&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000932%2Fabstract%3Frss%3Dyes Abstract: A simple model is presented for the description of relaxation, creep, and strain stiffening phenomena that are observed in parallel-fibered collagenous tissues such as ligaments and tendons. In the model formulation, the tissues are assumed to be composed of collagen fibers aligned along their physiological loading direction. The collagen fibers are gradually recruited under strain and are arranged in parallel with a Maxwell element which accounts for the viscoelasticity of the proteoglycan-rich matrix. Once straight, the collagen fibers are assumed to behave as linear elastic springs. Experimental data published by Hingorani et al. are used to estimate the five model parameters by fitting relaxation and strain stiffening data and the predictions are evaluated by using creep data... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332774 Mon, 30 May 2011 04:00:00 +0100 5332774 http://www.medworm.com/index.php?rid=5332786&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000981%2Fabstract%3Frss%3Dyes Abstract: An oscillatory platform can be used as a simple measuring instrument for modelling balancing capacity. We sought (1) to determine the test–retest reliability of the Lehr's damping ratio for characterizing the balancing ability on an unstable oscillatory platform of 20 healthy young and 20 healthy elderly participants and (2) to compare balancing ability on an unstable oscillatory platform between groups. Tests were performed during standing on both limbs and on one limb (dominant or non-dominant). The average of differences of the Lehr's damping ratio was 0.004±0.003 (3.77%±3.89%), and tests conducted at different times showed strong correlations (range 0.978–0.998). The average value of the Lehr's damping ratio was significantly smaller for elderly compared to young partic... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332786 Fri, 27 May 2011 04:00:00 +0100 5332786 http://www.medworm.com/index.php?rid=5332773&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000889%2Fabstract%3Frss%3Dyes Abstract: Currently, the study of ion composition and performance in human biofluids plays an important role in biomedical engineering research and technology. This field may become universal for human diagnostics; it allows early detection of different diseases in humans by measuring changes in ion behaviour in human biofluids. Practical experiments were conducted to analyse the liquid composite electrolyte conductivity in an alternating electric current field. These experiments allow the contribution of separate types of ions to the overall conductivity to be estimated. The method of estimating the concentration of active ions contained in biofluids is also introduced; it illustrates the possibility of performing qualitative and quantitative analysis over a wide range of concentrations a... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332773 Fri, 27 May 2011 04:00:00 +0100 5332773 http://www.medworm.com/index.php?rid=5332779&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000956%2Fabstract%3Frss%3Dyes Abstract: Breast augmentation surgery is a widespread practice for aesthetic purposes. Current techniques, however, are not able to reliably predict the desired final aspect of the breast after the intervention, whose success relies almost completely on the surgeon's skill. In this way, patient-specific methodologies capable of predicting the outcomes of such interventions are of particular interest. In this paper, a finite element biomechanical model of the breast of a female patient before an augmentation mammoplasty was generated using computer tomography images. Prosthesis insertion during surgery was simulated using the theory of finite elasticity. Hyperelastic constitutive models were considered for breast tissues and silicone implants. The deformed geometry obtained from finite elem... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332779 Wed, 25 May 2011 04:00:00 +0100 5332779 http://www.medworm.com/index.php?rid=5332778&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000968%2Fabstract%3Frss%3Dyes Abstract: The aim of this study was to extract multi-parametric measures characterizing different features of sit-to-stand (Si-St) and stand-to-sit (St-Si) transitions in older persons, using a single inertial sensor attached to the chest. Investigated parameters were transition's duration, range of trunk tilt, smoothness of transition pattern assessed by its fractal dimension, and trunk movement's dynamic described by local wavelet energy. A measurement protocol with a Si-St followed by a St-Si postural transition was performed by two groups of participants: the first group (N=79) included Frail Elderly subjects admitted to a post-acute rehabilitation facility and the second group (N=27) were healthy community-dwelling elderly persons. Subjects were also evaluated with Tinetti's POMA scal... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332778 Wed, 25 May 2011 04:00:00 +0100 5332778 http://www.medworm.com/index.php?rid=5332775&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000907%2Fabstract%3Frss%3Dyes Abstract: An adaptive step length estimation algorithm operating with optimal parameters and a movement status awareness algorithm are proposed. The proposed algorithm was developed as a means for increasing the accuracy in estimating walking distances. The algorithm was applied to pedestrian navigation system, ubiquitous health monitoring systems, and so forth. The algorithm's optimal parameters were derived after measurement errors were taken into consideration. The movement status awareness algorithm was designed using a walking characteristic called the acceleration variance. After estimating a subject's walking distance using the proposed algorithm, the measured error was 4.8% with respect to actual walking distance. Alternatively, estimating a subject's walking distance without the a... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332775 Wed, 25 May 2011 04:00:00 +0100 5332775 http://www.medworm.com/index.php?rid=5332776&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000890%2Fabstract%3Frss%3Dyes In this study we integrated between confocal-based cell-specific finite element (FE) modeling and Virtual Cell (VC) transport simulations in order to determine trends of relationship between externally applied compressive deformations and build-up rates of oxygen in myoblast cells, and to further test how mild culture temperature drops (∼3°C) might affect such trends. Geometries of two different cells were used, and each FE cell model was computationally subjected to large compressive deformations. Build-up of oxygen concentrations within the deformed cell shapes over time were calculated using the VC software. We found that the build-up of oxygen in the cells was slightly but consistently hindered when compressive cell deformations were applied. Temperature drops characteristic to isch... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5332776 Fri, 20 May 2011 04:00:00 +0100 5332776 http://www.medworm.com/index.php?rid=4840967&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311001007%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840967 Thu, 19 May 2011 23:34:46 +0100 4840967 http://www.medworm.com/index.php?rid=5158172&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000841%2Fabstract%3Frss%3Dyes Abstract: Wave propagation models of blood flow and blood pressure in arteries play an important role in cardiovascular research. For application of these models in patient-specific simulations a number of model parameters, that are inherently subject to uncertainties, are required. The goal of this study is to identify with a global sensitivity analysis the model parameters that influence the output the most. The improvement of the measurement accuracy of these parameters has largest consequences for the output statistics. A patient specific model is set up for the major arteries of the arm. In a Monte-Carlo study, 10 model parameters and the input blood volume flow (BVF) waveform are varied randomly within their uncertainty ranges over 3000 runs. The sensitivity in the output for each sy... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158172 Thu, 19 May 2011 23:00:00 +0100 5158172 http://www.medworm.com/index.php?rid=5158173&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000877%2Fabstract%3Frss%3Dyes Abstract: Endotracheal intubation is a complex medical procedure in which a ventilating tube is inserted into the human trachea. Improper positioning carries potentially fatal consequences and therefore confirmation of correct positioning is mandatory. This paper introduces a novel system for endotracheal tube position confirmation. The proposed system comprises a miniature complementary metal oxide silicon sensor (CMOS) attached to the tip of a semi rigid stylet and connected to a digital signal processor (DSP) with an integrated video acquisition component. Video signals are acquired and processed by a confirmation algorithm implemented on the processor. The confirmation approach is based on video image classification, i.e., identifying desired expected anatomical structures (upper trach... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158173 Mon, 09 May 2011 23:00:00 +0100 5158173 http://www.medworm.com/index.php?rid=5158174&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000865%2Fabstract%3Frss%3Dyes Abstract: Functional Electrical Stimulation (FES) is a well known clinical rehabilitation procedure, however the neural mechanisms that underlie this treatment at Central Nervous System (CNS) level are still not completely understood. Functional magnetic resonance imaging (fMRI) is a suitable tool to investigate effects of rehabilitative treatments on brain plasticity. Moreover, monitoring the effective executed movement is needed to correctly interpret activation maps, most of all in neurological patients where required motor tasks could be only partially accomplished. The proposed experimental set-up includes a 1.5T fMRI scanner, a motion capture system to acquire kinematic data, and an electro-stimulation device. The introduction of metallic devices and of stimulation current in the MRI... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158174 Sun, 08 May 2011 23:00:00 +0100 5158174 http://www.medworm.com/index.php?rid=5103230&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000786%2Fabstract%3Frss%3Dyes Abstract: In order to address the problem of blood flow over the endothelium in small arteries, the near-endothelial region is here studied in more detail. The method used is a finite-volume discretisation of a Lattice Boltzmann equation over unstructured grids, named unstructured Lattice Boltzmann equation (ULBE). It is a new scheme based on the idea of placing the unknown fields at the nodes of the mesh and evolving them based on the fluxes crossing the surfaces of the corresponding control volumes. The study shows a significant variation and a high sensitivity of wall shear stress to the height of the endothelium corrugation and the presence of erythrocytes. The latter were modelled as deformable, viscous particles within a fluid continuum. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5103230 Thu, 05 May 2011 23:00:00 +0100 5103230 http://www.medworm.com/index.php?rid=5158175&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000853%2Fabstract%3Frss%3Dyes Abstract: Vocoder simulation has been long applied as an effective tool to assess factors influencing the intelligibility of cochlear implants listeners. Considering that the temporal envelope information contained in contiguous bands of vocoded speech is correlated and redundant, this study examined the hypothesis that the intelligibility measure evaluating the distortions from a small number of selected envelope cues is sufficient to well predict the intelligibility scores. The speech intelligibility data from 80 conditions was collected from vocoder simulation experiments involving 22 normal-hearing listeners. The relative importance of temporal envelope information in cochlear-implant vocoded speech was modeled by correlating its speech-transmission indices (STIs) with the intelligibil... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158175 Wed, 04 May 2011 23:00:00 +0100 5158175 http://www.medworm.com/index.php?rid=5158171&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331100083X%2Fabstract%3Frss%3Dyes Abstract: Distraction osteogenesis can result in high forces developing in the limb. To determine and control the distraction forces (DF), a motorized distractor driven by feedback from DF was developed and used to lengthen the tibiae of 6 sheep undergoing distraction osteogenesis. The forces were measured continually, and, in 4 of the sheep, a force threshold was set, above which an increase in rate was initiated. The rate kept increasing to a set limit if forces remained above the threshold; otherwise, the rate was decreased. Radiographs were acquired biweekly, and muscle samples were analyzed from both the operated and contralateral limbs upon termination of the experiment. Results demonstrated a drop in DF associated with increased lengthening rate, attributed to separation of the call... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158171 Sun, 01 May 2011 23:00:00 +0100 5158171 http://www.medworm.com/index.php?rid=5158170&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000816%2Fabstract%3Frss%3Dyes Abstract: The smallest functional unit of cancellous bone is the single trabecula. To investigate its influence at the macroscopic level, a mechanical characterization is required.The aim of this work is to present a new procedure for measuring the elastic behavior of a single trabecula, assumed as an isotropic material, by means of a bending protocol. Our experimental setup permits the measurement of the bending force and deflection of a single trabecula within the natural network. The exact geometry of the trabecula is attained by using a laser scanning microscopy of the labeled sample and subsequently using it as the input for FE simulation. The results between the FE analysis and experimental data are compared in order to determine an isotropic elastic modulus of the trabecula.The syst... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158170 Sun, 01 May 2011 23:00:00 +0100 5158170 http://www.medworm.com/index.php?rid=5103225&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000828%2Fabstract%3Frss%3Dyes The 2nd Micro and Nano Flows Conference, MNF2009, was held at Brunel University, Uxbridge, West London, UK, 1–2 September 2009, attracting around 115 participants from the UK and overseas. The MNF conference series originated in 2006 with a two-day colloquium held at the University of Strathclyde, Glasgow. These conferences provide a forum for scientists and engineers working in the field to present results of their recent research and to discuss issues that need resolving in progressing the understanding in the areas of biofluid mechanics and thermofluids engineering. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5103225 Thu, 28 Apr 2011 23:00:00 +0100 5103225 http://www.medworm.com/index.php?rid=5158169&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000804%2Fabstract%3Frss%3Dyes This study aimed to determine if the contra-lateral bone is a suitable control for the purpose of quantifying bone remodelling. CT scans of 8 pairs of ovine tibia were used to determine the likeness of left and right bones. The deviation between the outer surfaces of the bone pairs was used to quantify geometric similarity. The density differences were determined by dividing the bones into discrete volumes along the shaft of the tibia. Density differences were also determined for fractured and contra-lateral bone pairs to determine the magnitude of implant related remodelling. Left and right ovine tibiae were found to have a high degree of similarity with differences of less than 1.0mm in the outer surface deviation and density difference of less than 5% in over 90% of the shaft region. Th... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158169 Sun, 17 Apr 2011 23:00:00 +0100 5158169 http://www.medworm.com/index.php?rid=5158168&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000798%2Fabstract%3Frss%3Dyes Abstract: Detection of nonlinearity should be the first step before any analysis of nonlinearity or nonlinear behavior in biological signal. The question is which method should be used in each case and which one can best respect the different characteristics of the signals under investigation. In this paper we compare three methods widely used in nonlinearity detection: approximate entropy, correntropy and time reversibility. The false alarm rates with the numbers of surrogates for the three methods were computed on linear, nonlinear stationary and nonlinear nonstationary signals. The results indicate the superiority of time reversibility over the other methods for detecting linearity and nonlinearity in different signal types. The application of time reversibility on uterine electromyogra... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158168 Sun, 17 Apr 2011 23:00:00 +0100 5158168 http://www.medworm.com/index.php?rid=5158166&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000671%2Fabstract%3Frss%3Dyes Abstract: Functional electrical stimulation is commonly used to restore function in post-stroke patients in upper and lower limb applications. Location of the electrodes can be a problem hence some research groups have begun to experiment with electrode arrays. Electrode arrays are interfaced with a thin continuous hydrogel sheet which is high resistivity to reduce transverse currents between electrodes in the array. Research using electrode arrays has all been conducted in a laboratory environment over short time periods but it is suspected that this approach will not be feasible over longer time periods due to changes in hydrogel resistivity.High resistivity hydrogel samples were tested by leaving them in contact with the skin over a seven day period. The samples became extremely conduct... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158166 Sun, 10 Apr 2011 23:00:00 +0100 5158166 http://www.medworm.com/index.php?rid=5158163&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000622%2Fabstract%3Frss%3Dyes Abstract: Segmental measurements of limb resistances permit to evaluate the regional distribution of fat-free-mass (FFM). As shown by Organ et al. (J Appl Physiol 1994;77:98–112) “virtual” limb resistances can be measured with only peripheral electrodes at ankle and wrist, which is faster and does not require undressing. This paper presents a different method for obtaining “virtual” limb resistances from peripheral electrodes and compares it with that of Organ et al. and with segmental measurements using same protocol. It is found that virtual arm resistances of both methods were overestimated as compared to segmental values, by 6.8% in men and 5.8% in women for our method and by 7.4% and 8% for Organ et al. one. Virtual leg resistances were found, for both methods, to be slightl... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158163 Sun, 10 Apr 2011 23:00:00 +0100 5158163 http://www.medworm.com/index.php?rid=5158162&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000609%2Fabstract%3Frss%3Dyes This study developed and assessed a computerized scheme to detect breast abnormalities and predict the risk of developing cancer based on bilateral mammographic tissue asymmetry. A digital mammography database of 100 randomly selected negative cases and 100 positive cases for having high-risk of developing breast cancer was established. Each case includes four images of cranio-caudal (CC) and medio-lateral oblique (MLO) views of the left and right breast. To detect bilateral mammographic tissue asymmetry, a pool of 20 computed features was assembled. A genetic algorithm was applied to select optimal features and build an artificial neural network based classifier to predict the likelihood of a test case being positive. The leave-one-case-out validation method was used to evaluate the class... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158162 Sun, 10 Apr 2011 23:00:00 +0100 5158162 http://www.medworm.com/index.php?rid=5158161&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331100066X%2Fabstract%3Frss%3Dyes Abstract: This paper proposes a novel method for fast 3D reconstructions of the scoliotic spine from two planar radiographs. The method uses a statistical model of the shape of the spine for computing the 3D reconstruction that best matches the user input (about 7 control points per radiograph). In addition, the spine was modelled as an articulated structure to take advantage of the dependencies between adjacent vertebrae in terms of location, orientation and shape.The accuracy of the method was assessed for a total of 30 patients with mild to severe scoliosis (Cobb angle [22°, 70°]) by comparison with a previous validated method. Reconstruction time was 90s for mild patients, and 110s for severe. Results show an accuracy of ∼0.5mm locating vertebrae, while orientation accuracy was up ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158161 Sun, 10 Apr 2011 23:00:00 +0100 5158161 http://www.medworm.com/index.php?rid=5158167&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000658%2Fabstract%3Frss%3Dyes Abstract: Two new prototype assembly methods have been evaluated for biosensors that combine an integrated circuit (IC) sensor with a culture chamber. The first method uses a poly-ethylene glycol (PEG) mould to mask the IC sensor during application of a room temperature vulcanising (RTV) silicone elastomer used to insulate the bondpads and bondwires. The second method utilises the ‘partial encapsulation’ service offered by Quik-Pak, USA. Both methods were shown to provide good electrical insulation and demonstrated biocompatibility with the NG108-15 cell line. These methods are particularly useful for the assembly of low-cost ICs with a small ( (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158167 Thu, 07 Apr 2011 23:00:00 +0100 5158167 http://www.medworm.com/index.php?rid=5158165&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000646%2Fabstract%3Frss%3Dyes Abstract: The optimum time to treat abdominal aortic aneurysms (AAAs) still remains an uncertain issue. The decision to intervene does not take in account the effects that wall curvature, intraluminal thrombus (ILT) properties and thickness have on rupture. The role of ILT in aneurysm dynamics and rupture has been controversial. In vitro testing of four silicone AAA models incorporating the ILT and aortic bifurcation was studied under physiological conditions. Pressures (P) and diameters (D) were analysed for models with and without ILT at different locations. The diametral strain, compliance and P/D curves were influenced by the presence, elastic stiffness and thickness of the ILT. In this case, the inclusion of ILT reduced the lumen area by 77% that resulted in a 0.5–81% reduction in c... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158165 Thu, 07 Apr 2011 23:00:00 +0100 5158165 http://www.medworm.com/index.php?rid=5158164&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000634%2Fabstract%3Frss%3Dyes Abstract: A new sensor array intended to accurately and directly measure spatial and time-dependent pressures within a highly curved biological intra-articular joint was developed and tested.To evaluate performance of the new sensor array for application within intra-articular joints generally, and specifically to fit within the relatively restrictive space of the lumbar spine facet joint, geometric constraints of length, width, thickness and sensor spatial resolution were evaluated. Additionally, the effects of sensor array curvature, frequency response, linearity, drift, hysteresis, repeatability, and total system cost were assessed.The new sensor array was approximately 0.6mm in thickness, scalable to below the nominal 12mm wide by 15 high lumbar spine facet joint size, offered no inher... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158164 Thu, 07 Apr 2011 23:00:00 +0100 5158164 http://www.medworm.com/index.php?rid=4683936&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000695%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683936 Thu, 07 Apr 2011 17:56:31 +0100 4683936 http://www.medworm.com/index.php?rid=5158176&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000610%2Fabstract%3Frss%3Dyes We buy products because we find them useful, but also appeal to our aesthetic senses. We buy glasses as a statement of the personal image we wish to project to the world. We choose chairs that complement the interior design of our homes. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158176 Wed, 06 Apr 2011 23:00:00 +0100 5158176 http://www.medworm.com/index.php?rid=5158160&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000592%2Fabstract%3Frss%3Dyes This study introduced synergy matrices to extract fluid wrist movement intents by sEMG to allow individuals with wrist amputations to use wrist prostheses. A non-negative muscle synergy matrix was used to map muscle activities in the forearm into four predefined wrist movement intents (flexion/extension and radial/ulnar deviation). The directions of the predefined intents were constrained to two perpendicular axes, so each movement spanned only a one-dimensional space. A joint synergy matrix was used to span the whole two-dimensional space by combining the four wrist movement intents. Ten healthy subjects volunteered for a validation experiment, which was built as a virtual environment in which people with wrist amputation could receive myoelectric control training. The results showed that... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158160 Fri, 18 Mar 2011 00:00:00 +0100 5158160 http://www.medworm.com/index.php?rid=4968193&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000439%2Fabstract%3Frss%3Dyes In this study the wrist kinematics and the wrist extensors’ musculotendon patterns were investigated during a manual task believed to elicit LE symptoms in susceptible subjects. A 42-year-old right-handed male, with no history of LE, performed a repetitive movement involving pushing and turning a spring-loaded mechanism. Motion capture data were acquired for the upper limb and an inverse kinematic and dynamic analysis was subsequently carried out. Results illustrated the presence of eccentric contractions sustained by the extensor carpi radialis longus (ECRL), together with an almost constant level of tendon strain of both extensor carpi radialis brevis (ECRB) and extensor digitorum communis lateral (EDCL) branch. It is believed that these factors may partly contribute to the onset of LE... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968193 Thu, 17 Mar 2011 00:00:00 +0100 4968193 http://www.medworm.com/index.php?rid=4591809&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331100049X%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591809 Wed, 16 Mar 2011 00:19:59 +0100 4591809 http://www.medworm.com/index.php?rid=5158159&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000452%2Fabstract%3Frss%3Dyes Abstract: In our laboratory, an implantable centrifugal blood pump (CBP) with a two degrees-of-freedom radially controlled magnetic bearing (MB) to support the impeller without contact has been developed to assist the pumping function of the weakened heart ventricle. In order to maintain the function of the CBP after damage to the electromagnets (EMs) of the MB, fault-tolerant strategies for the CBP are proposed in this study.Using a redundant MB design, magnetic levitation of the impeller was maintained with damage to up to two out of a total of four EMs of the MB; with damage to three EMs, contact-free support of the impeller was achieved using hydrodynamic and electromagnetic forces; and with damage to all four EMs, the pump operating point, of 5l/min against 100mmHg, was achieved using... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158159 Tue, 08 Mar 2011 00:00:00 +0100 5158159 http://www.medworm.com/index.php?rid=5158158&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000464%2Fabstract%3Frss%3Dyes Abstract: The overall aim of this study was to assess the accuracy, reproducibility and stability of a high resolution passive stereophotogrammetry system to image a female mannequin torso, to validate measurements made on the textured virtual surface compared with those obtained using manual techniques and to develop an approach to make objective measurements of the female breast. 3D surface imaging was carried out on a textured female torso and measurements made in accordance with the system of mammometrics. Linear errors in measurements were less than 0.5mm, system calibration produced errors of less than 1.0mm over 94% over the surface and intra-rater reliability measured by ICC=0.999. The mean difference between manual and digital curved surface distances was 1.36mm with maximum and m... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158158 Tue, 08 Mar 2011 00:00:00 +0100 5158158 http://www.medworm.com/index.php?rid=5158157&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000440%2Fabstract%3Frss%3Dyes Abstract: We developed and analyzed an inverse numerical model based on Fick's second law on the dynamics of drug release. In contrast to previous models which required two state descriptions of diffusion for long- and short-term release processes, our model is valid for the entire release process. The proposed model may be used for identifying and reducing experimental errors associated with measurements of diffusion based release kinetics. Knowing the initial and boundary conditions, and assuming Fick's second law to be appropriate, we use the methods of Lagrange multiplier along with least-square algorithms to define a cost function which is discretized using finite difference methods and is optimized so as to minimize errors. Our model can describe diffusion based release kinetics for ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5158157 Tue, 08 Mar 2011 00:00:00 +0100 5158157 http://www.medworm.com/index.php?rid=4968190&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000427%2Fabstract%3Frss%3Dyes Abstract: In recent years several world-wide ambient assisted living (AAL) programs have been activated in order to improve the quality of life of older people, and to strengthen the industrial base through the use of information and communication technologies. An important issue is extending the time that older people can live in their home environment, by increasing their autonomy and helping them to carry out activities of daily livings (ADLs). Research in the automatic detection of falls has received a lot of attention, with the object of enhancing safety, emergency response and independence of the elderly, at the same time comparing the social and economic costs related to fall accidents. In this work, an algorithmic framework to detect falls by using a 3D time-of-flight vision techno... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968190 Tue, 08 Mar 2011 00:00:00 +0100 4968190 http://www.medworm.com/index.php?rid=4968187&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000166%2Fabstract%3Frss%3Dyes Abstract: Physiological relevance of parameters of three arterial models, denominated W4P, W4S and IVW, was assessed by computation of parameter-related generalized sensitivity functions (GSFs), which allow the definition of heart-cycle time intervals where the information content of experimental data, useful for estimation of each model parameter, is concentrated. The W4P and W4S are derived from the three-element windkessel by connecting an inductance, L, in parallel or in series, respectively, with aortic characteristic impedance, Rc. In the IVW, L is placed in series at the input of a viscoelastic windkessel, incorporating a Voigt cell (a resistor, Rd, in series with a capacitor, C). Pressure and flow measured in the ascending aorta of five ferrets and five dogs were used to estimate a... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968187 Mon, 07 Mar 2011 00:00:00 +0100 4968187 http://www.medworm.com/index.php?rid=4968179&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000415%2Fabstract%3Frss%3Dyes Abstract: The present study focusses on the determination, comparison and constitutive modelling of the passive mechanical properties of the swine carotid artery over very long stretches in both proximal and distal regions. Special attention is paid to the histological and mechanical variations of these properties depending on the proximity to the heart. The results can have clinical relevance, especially in the research field of intravascular device design. Before the final clinical trials on humans, research in the vascular area is conducted on animal models, swine being the most common due to the similarities between the human and swine cardiovascular systems as well as the fact that the swine size is suitable for testing devices, in this case endovascular carotid systems. The design of... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968179 Mon, 07 Mar 2011 00:00:00 +0100 4968179 http://www.medworm.com/index.php?rid=4968191&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000178%2Fabstract%3Frss%3Dyes Abstract: A mechanical-conditioning bioreactor has been developed to provide bi-axial loading to three-dimensional (3D) tissue constructs within a highly controlled environment. The computer-controlled bioreactor is capable of applying axial compressive and shear deformations, individually or simultaneously at various regimes of strain and frequency. The reliability and reproducibility of the system were verified through validation of the spatial and temporal accuracy of platen movement, which was maintained over the operating length of the system. In the presence of actual specimens, the system was verified to be able to deliver precise bi-axial load to the specimens, in which the deformation of every specimen was observed to be relatively homogeneous. The primary use of the bioreactor is... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968191 Mon, 28 Feb 2011 00:00:00 +0100 4968191 http://www.medworm.com/index.php?rid=4968189&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331100018X%2Fabstract%3Frss%3Dyes Abstract: Truly representative architectural parameters of trabeculea can be extremely difficult to achieve based on scanning images because of variable porosity and distribution of trabeculae within the specific overall scanned volume of bone. Accordingly, in present study different selective volume of interests, measured from centroid of μ-CT scanned human vertebral body, were analyzed to determine the architectural parameters (BV/TV, BS/BV, Tb.Th, Tb.N, Tb.Sp) of trabeculae within these volumes and to suggest an optimal volume for representative architectural parameters of the overall scanned volume. Nonlinear curve fitting method was also applied to obtain the correlation between the parameters and the volume of interests. The results show different volumes of interests give different... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968189 Mon, 28 Feb 2011 00:00:00 +0100 4968189 http://www.medworm.com/index.php?rid=4968188&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000191%2Fabstract%3Frss%3Dyes We present a finite element based simulation and analysis method to describe the spatial extent of stimulation and the effects of electrode–tissue interactions in subretinal prostheses. In particular, we estimate the threshold stimulation current needed to depolarise and evoke action potentials in the ganglion cells to be stimulated at a particular distance from the electrode. This is achieved through the application of a threshold electric field to a spherical neuronal soma model of a retinal ganglion cell under consideration. Threshold stimulation currents and the lateral extent of the stimulation zone were computed for disc microelectrodes in subretinal stimulation mode. Recent evidence indicates a decrease in threshold charge with time following subretinal implantation. Consequently,... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968188 Mon, 28 Feb 2011 00:00:00 +0100 4968188 http://www.medworm.com/index.php?rid=4968186&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000154%2Fabstract%3Frss%3Dyes Abstract: The present study investigated the effect of metal plasma immersion ion implantation and deposition (MePIIID) process parameters, i.e., plasma sources of magnesium and calcium, ion dose, and acceleration voltage on the surface chemistry and morphology of screw-type titanium implants that have been most widely used for osseointegrated implants. It is found that irrespective of plasma ion source, surface topography and roughness showed no differences at the nanometer level; that atom concentrations increased with ion dose but decreased with acceleration voltage. Data obtained from X-ray photoelectron spectroscopy and auger electron spectroscopy suggested that MePIIID process produces ‘intermixed’ layer of cathodic arc deposition and plasma immersion ion implantation. The MePIII... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968186 Mon, 21 Feb 2011 00:00:00 +0100 4968186 http://www.medworm.com/index.php?rid=4968192&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000142%2Fabstract%3Frss%3Dyes Abstract: Incisional hernias following median laparotomy have a high incidence and recurrence rate after repair, so that a better understanding of the linea alba biomechanics is desirable. The mechanical stress exerted on the linea alba in living humans is primarily generated by the musculature. In this human cadaver study, intraabdominal pressure was simulated by insertion of a balloon that was increasingly filled to maximal pressures of 200mbar. The related forces acting transversely on the linea alba at maximum pressure were found to be between 41.6 and 52.2N/cm (mean=45.9N/cm), which is in agreement with a recent modeling of the related forces. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968192 Fri, 18 Feb 2011 00:00:00 +0100 4968192 http://www.medworm.com/index.php?rid=4968183&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000117%2Fabstract%3Frss%3Dyes In this study, we address the limitations of two common TWA estimation methods, spectral method (SM) and modified moving average (MMA). To overcome their limitations, we propose a modified TWA quantification framework, called Adaptive SM, that uses non-linear time–frequency distribution (TFD). In order to increase the robustness of TWA detection in ambulatory ECGs, we also propose a new technique, called non-negative matrix factorization (NMF)-Adaptive SM. We present the analytical background of these methods, and evaluate their accuracy in detecting synthetic TWA signal in simulated and real-world ambulatory ECG recordings under conditions of noise and data non-stationarity. The results of the numerical simulations support the effectiveness of the proposed approaches for TWA analysis, w... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968183 Fri, 18 Feb 2011 00:00:00 +0100 4968183 http://www.medworm.com/index.php?rid=4968185&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000130%2Fabstract%3Frss%3Dyes Abstract: The emergence of full field laser Doppler blood flow imaging systems based on CMOS camera technology means that a large amount of data from each pixel in the image needs to be processed rapidly and system resources need to be used efficiently. Conventional processing algorithms that are utilized in single point or scanning systems are therefore not an ideal solution as they will consume too much system resource. Two processing algorithms that address this problem are described and efficiently implemented in a field programmable gate array. The algorithms are simple enough to use low system resource but effective enough to produce accurate flow measurements. This enables the processing unit to be integrated entirely in an embedded system, such as in an application-specific integra... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968185 Mon, 14 Feb 2011 00:00:00 +0100 4968185 http://www.medworm.com/index.php?rid=4968184&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000129%2Fabstract%3Frss%3Dyes Abstract: Tortuosity can be described as the variation in blood vessel curvature. Abnormal tortuosity is an important clinical indicator of various conditions. Despite considerable research, there has been very little agreement on an accurate, unique measure of this phenomenon for clinical applications. It has been demonstrated that a single value is insufficient to describe vessel tortuosity. In this work, the fast Fourier transform of the vessel's curvature as a measure of tortuosity is introduced. Spectral analysis of a suite of computed-simulated vessels, a phantom and clinical data is carried out. Observation of the acquired spectra permits detection of the local curvature variations. Spectral analysis of curvature provides a compact and graphic representation of tortuosity. This pape... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968184 Mon, 14 Feb 2011 00:00:00 +0100 4968184 http://www.medworm.com/index.php?rid=4840969&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002961%2Fabstract%3Frss%3Dyes Abstract: Based on a single time-point study of 34 healthy and 19 osteoarthritic knees in three different age groups (early, middle and late adulthood), this paper reports the potential of knee acoustic emission as a biomarker to monitor joint ageing and degeneration. Measurements were made of short transient high frequency acoustic emission signals generated by knee joints under stress during repeated sit–stand–sit movements along with joint angle. A statistically significant feature profile was established using a four-phase model of sit–stand–sit movements and two waveform features. The four-phase movement model is derived from joint angle measurement during repeated sit–stand–sit movements, and it consists of the ascending-acceleration and ascending-deceleration phases in t... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840969 Fri, 11 Feb 2011 00:00:00 +0100 4840969 http://www.medworm.com/index.php?rid=4840982&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000051%2Fabstract%3Frss%3Dyes Abstract: In this work, we report the development of a novel device, integrated into a shoe, to monitor plantar pressure under real-life conditions by reducing the spatial and temporal resolution. The device consists of a shoe insole with seven pressure-sensitive conductive rubber sensors and a wireless data transmission unit incorporated into a smaller measurement unit. One advantage of this approach is that the mass and volume of the measurement unit are less than 1/10th and 1/50th, respectively, of that reported for other devices. A comparison experiment was conducted for validation of the device using the F-scan system, and the initial test of the device was conducted by recording unobstructed gaits of one young adult subject and two elderly subjects. Each subject performed a straight,... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840982 Thu, 10 Feb 2011 00:00:00 +0100 4840982 http://www.medworm.com/index.php?rid=4968181&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000087%2Fabstract%3Frss%3Dyes Abstract: Assessment of coronary flow reserve (CFR) with a commercially available pressure-sensor-tipped guide wire using the principle of thermal anemometry could provide major clinical benefits both in determining and in distinguishing between epicardial and microvascular coronary artery disease. In constant-temperature thermal anemometry, the electrical power required to maintain an element at a constant temperature is a measure for the local shear rate. Here, the feasibility of applying this thermoconvection method to a pressure-sensing guide wire is investigated using an in vitro model.A theoretical relation between electrical power and steady shear rate based on boundary layer theory was tested in an experimental set-up. In steady flow, a reproducible relation between electrical powe... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968181 Thu, 03 Feb 2011 00:00:00 +0100 4968181 http://www.medworm.com/index.php?rid=4968180&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000099%2Fabstract%3Frss%3Dyes Abstract: Osteoarthritis is a chronic degenerative disease affecting body joints. Abnormal mechanical loading could be an initiating factor of cartilage damage, by influencing chondrocytes activity. To date, devices performing mechanical studies of viable tissues are mostly uniaxial. In this work, we developed and validated a multi-axial device for static and dynamic mechanical testing of viable soft tissues. The system, named RPETS, is composed of a motor driven indenter, moving vertically and horizontally along the bottom of a tank containing tissue samples and it can apply combined compression, sliding, and rolling on viable samples. Validation studies were performed with standard rubber and bovine nasal cartilage tissue. Static tests demonstrated that the system is comparable to existi... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968180 Thu, 03 Feb 2011 00:00:00 +0100 4968180 http://www.medworm.com/index.php?rid=4840980&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000075%2Fabstract%3Frss%3Dyes This study investigated the validity of a portable gait assessment tool in objectively assessing the temporal gait parameters in subjects with spinal cord injury. The portable gait assessment tool consisted of a pair of insoles instrumented with force sensing resistors that were strategically positioned over the sole of each foot.Aim: To demonstrate the validity of the gait assessment tool by assessing the change in walking ability in incomplete spinal cord injured (ISCI) subjects, who participated in a robot-assisted gait training program.Methods: Eighteen subjects with either an acute or chronic ISCI participated in this study (age range 26–63 years). Each subject participated in a robot assisted gait training programme for 6 weeks. Assessments were performed using the gait assessment ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840980 Wed, 02 Feb 2011 00:00:00 +0100 4840980 http://www.medworm.com/index.php?rid=4968182&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000105%2Fabstract%3Frss%3Dyes Abstract: Fetal activity is an important indicator of fetal well-being. It is proposed to assess this activity using the pulsed wave Doppler method to collect fetal activity data and dedicated software for on-line processing. The system, addressed to 3rd trimester pregnancies, provides information on presence of pseudobreathing, the heart rate trace, the fetal movement trace, the movement velocity spectrogram, histograms of the velocity and acceleration of both the body movements and pseudobreathing, parameters of these histograms (mean values, standard deviations, shape descriptors), and cumulative counts of the velocity histograms. These parameters form the feature vector of the fetal activity. The system was validated by simultaneous echographic and cardiotocographic recordings and duri... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4968182 Mon, 31 Jan 2011 00:00:00 +0100 4968182 http://www.medworm.com/index.php?rid=4840981&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000063%2Fabstract%3Frss%3Dyes Abstract: Time irreversibility is a subject of increasing interest in biomedicine. However, measurements of this property have been limited to a two-dimensional state space and few effective methods for high-dimensional time irreversibility testing have been reported. Using a strategy based on multiple bidimensional tests, we propose an extension of the traditional low-dimensional method for the estimation of time irreversibility in a high-dimensional state space. The method is applied to both physiological and synthetic interbeat (RR) intervals and the results indicate that time irreversibility should be an intrinsic characteristic of human RR intervals and is complementary to the conventional properties that can be measured in the time and frequency domain. Furthermore, a loss of time ir... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840981 Fri, 28 Jan 2011 00:00:00 +0100 4840981 http://www.medworm.com/index.php?rid=4840974&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002997%2Fabstract%3Frss%3Dyes Abstract: A decomposed electromyographic (EMG) signal provides information that can be used clinically or for physiological investigation. However, in all instances the validity of the extracted motor unit potential trains (MUPTs) must first be determined because, as with all pattern recognition applications, errors will occur during decomposition. Moreover, detecting invalid MUPTs during EMG signal decomposition can enhance decompositions results. Eight methods to validate an extracted MUPT using its motor unit potential (MUP) shape information were studied. These MUPT validation methods are based on existing cluster analysis algorithms, four were newly developed adaptive methods and four were classical cluster validation methods. The methods evaluate the shapes of the MUPs of a MUPT to d... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840974 Thu, 27 Jan 2011 00:00:00 +0100 4840974 http://www.medworm.com/index.php?rid=4840972&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002936%2Fabstract%3Frss%3Dyes Abstract: Quantitative description of cardiac motion is desirable to assist in detecting myocardial abnormalities from gated myocardial perfusion (GMP) emission computed tomography (ECT) images. While “optical flow” type of cardiac motion estimation (ME) techniques have been developed in the past, there has been no quantitative evaluation of their performance. Moreover, no investigation has been performed in terms of applying an ME technique to quantify cardiac motion abnormalities. Using the four-dimensional NCAT beating heart phantom with known built-in motion, the current work aimed at addressing the aforementioned two issues. A three-dimensional cardiac ME technique was developed to search for a motion vector field (MVF) that establishes voxel-by-voxel correspondence between two GM... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840972 Thu, 27 Jan 2011 00:00:00 +0100 4840972 http://www.medworm.com/index.php?rid=4840984&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000038%2Fabstract%3Frss%3Dyes This article describes the construction and application of a new system capable of locally modifying the epicardial temperature of isolated hearts and of carrying out cardiac mapping with sufficient spatial resolution. The system is based on a thermoelectric refrigerator and an array of 128 stainless steel unipolar electrodes in encapsulated epoxy of good thermal conductivity. The surface of the electrode is shaped to match the ventricular curvature. The electrode-device was tested on 7 isolated perfused rabbit hearts following the Langendorff technique. Quality recordings were obtained for the left ventricle at temperatures of 37°C, 22°C and 42°C. The effects of temperature were explored in relation to two electrophysiological parameters: the QT interval during sinus rhythm and the VV ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840984 Mon, 24 Jan 2011 00:00:00 +0100 4840984 http://www.medworm.com/index.php?rid=4840979&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453311000026%2Fabstract%3Frss%3Dyes We examined this effect by using a finite element modeling approach. Firstly, a geometric model was created by scanning a polyethylene replica of fetal skull model with a white light three-dimensional scanner. Secondly, a nonlinear finite element model was proposed based on the geometric model. Next, the simulation results of the proposed model were verified against the experimental data reported in other literatures and they showed good agreement with the experimental observations. After this validation, the proposed model was used to simulate the fetal skull deformations under different labor forces. Simulation results illustrated that the fetal skull diameters and modified molding index (MMI) increased when the labor force was increased. Parietal bone around bregma and frontal bone arou... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840979 Fri, 21 Jan 2011 00:00:00 +0100 4840979 http://www.medworm.com/index.php?rid=4840977&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310003139%2Fabstract%3Frss%3Dyes This study investigates the application of non-destructive testing based on the impedance theory in the cyclic fatigue evaluation of endodontic Ni–Ti rotary instruments. Fifty Ni–Ti ProTaper instruments were divided into five groups (n=10 in Groups A to E). Groups A to D were subjected to cyclic fatigue within an artificial canal (Group E was the control group). The mean value of the total life limit (TLL), defined as the instrument being rotated until fracture occurred was found to be 104s in Group A. Each rotary instrument in Groups B, C and D were rotated until the tested instruments reached 80% (84s), 60% (62s) and 40% (42s) of the TLL. After fatigue testing, each rotary instrument was mounted onto a custom-developed non-destructive testing device to give the tip of the instrument ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840977 Fri, 21 Jan 2011 00:00:00 +0100 4840977 http://www.medworm.com/index.php?rid=4683939&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002766%2Fabstract%3Frss%3Dyes Abstract: The purpose of this study was to develop an algorithm for automated muscle fatigue detection in sports related scenarios. Surface electromyography (sEMG) of the biceps muscle was recorded from ten subjects performing semi-isometric (i.e., attempted isometric) contraction until fatigue. For training and testing purposes, the signals were labelled in two classes (Non-Fatigue and Fatigue), with the labelling being determined by a fuzzy classifier using elbow angle and its standard deviation as inputs. A genetic algorithm was used for evolving a pseudo-wavelet function for optimising the detection of muscle fatigue on any unseen sEMG signals. Tuning of the generalised evolved pseudo-wavelet function was based on the decomposition of twenty sEMG trials. After completing twenty indepen... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683939 Fri, 21 Jan 2011 00:00:00 +0100 4683939 http://www.medworm.com/index.php?rid=4840970&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331000295X%2Fabstract%3Frss%3Dyes This article introduces a method and step-by-step instructions for the design of a low-cost, flexible electrogoniometer, suitable for kinesiology, rehabilitation, and biometric applications. Two unidirectional flexible sensors are placed back-to-back, and a multivariate linear regression model was used to combine measurements from the two sensors. Following a short calibration procedure, the electrogoniometer can be reliably used for measurement of flexion/extension angles of various hinge joints. The performance of the goniometer has been tested on a population of 21 healthy subjects performing flexion/extension of index finger, wrist and elbow. The proposed device achieves the quality of joint angle measurements comparable to that of commercial electrogoniometers, while having a signific... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840970 Wed, 19 Jan 2011 00:00:00 +0100 4840970 http://www.medworm.com/index.php?rid=4840985&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002985%2Fabstract%3Frss%3Dyes Abstract: We combine linear and nonlinear signal analysis techniques to investigate the transmission of pressure signals along a one-dimensional model of fluid flow in an elastic tube. We derive a simple, generally applicable measure for the robustness of a simulated vessel against in vivo pressure fluctuations, based on quantifying the degree of synchronization between proximal and distal pressure pulses. The practical use of this measure will be in its application to simulated pulses generated in response to a stochastic forcing term mimicking biological variations of root pressure in arterial blood flow. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840985 Tue, 18 Jan 2011 00:00:00 +0100 4840985 http://www.medworm.com/index.php?rid=4840978&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310003140%2Fabstract%3Frss%3Dyes In this study, a novel force-sensitive micro-robot applied a rich set of three-dimensional deformations to the skin surface of different areas of the arms of 20 volunteers. The force–displacement response of each area in different directions was measured. All tested areas exhibited a non-linear, viscoelastic, and anisotropic force–displacement response. There was a wide quantitative variation in the stiffness of the response. For the right anterior forearm, the ratio of the maximum probe reaction force to maximum probe displacement ranged from 0.44Nmm−1 to 1.45Nmm−1. All volunteers exhibited similar qualitative anisotropic characteristics. For the anterior right forearm, the stiffest force–displacement response was when the probe displaced along the longitudinal axis of the forea... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840978 Tue, 18 Jan 2011 00:00:00 +0100 4840978 http://www.medworm.com/index.php?rid=4840975&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310003127%2Fabstract%3Frss%3Dyes Abstract: Additive manufacturing, covering processes frequently referred to as rapid prototyping and rapid manufacturing, provides new opportunities in the manufacture of highly complex and custom-fitting medical devices and products. Whilst many medical applications of AM have been explored and physical properties of the resulting parts have been studied, the characterisation of AM materials in computed tomography has not been explored. The aim of this study was to determine the CT number of commonly used AM materials. There are many potential applications of the information resulting from this study in the design and manufacture of wearable medical devices, implants, prostheses and medical imaging test phantoms. A selection of 19 AM material samples were CT scanned and the resultant imag... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840975 Tue, 18 Jan 2011 00:00:00 +0100 4840975 http://www.medworm.com/index.php?rid=4840971&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002948%2Fabstract%3Frss%3Dyes Abstract: There are methodological concerns with combined use of transcranial Doppler (TCD) and Finapres to measure dynamic cerebral autoregulation. The Finapres calibration mechanism (“physiocal”) causes interruptions to blood pressure recordings. Also, TCD is subject to signal loss due to probe movement. We assessed the effects of “physiocals” and TCD signal loss on transfer function estimates in recordings of 45 healthy subjects. We added artificial “physiocals” and removed sections of TCD signal from 5min Finapres and TCD recordings. We also compared transfer function results from 5min time series with time series as short as 1min. Accurate transfer function estimates can be achieved in the 0.03–0.07Hz band using beat-by-beat data with linear interpolation, while data los... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840971 Tue, 18 Jan 2011 00:00:00 +0100 4840971 http://www.medworm.com/index.php?rid=4683937&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002821%2Fabstract%3Frss%3Dyes This study proposes that directly embedded sensors within the femoral stem of the implant will reduce signal attenuation effects and eliminate potential complications and variability associated with fixing the sensor to the sample. Data was collected during in vitro testing of implanted constructs, and information from both embedded and externally mounted AE sensors was compared and corroborated by micro-Computed Tomography (micro-CT) images taken before and after testing. The results of this study indicate that the embedded sensors gave a closer corroboration to observed damage using micro-CT and were less affected by unwanted noise sources. This has significant implications for the use of AE in assessing the state of THR constructs in vitro and it is hypothesised that directly embedded A... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683937 Tue, 18 Jan 2011 00:00:00 +0100 4683937 http://www.medworm.com/index.php?rid=4840973&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310003000%2Fabstract%3Frss%3Dyes Abstract: Stents play an important role in management of cerebral aneurysms. A stent reconstructs the parent artery, assists coil embolization, and decreases flow activity within an aneurysm. However, an in-stent stenosis often occurs within the stented artery and compromises the circulation at the parent artery. Hemodynamic basis of re-stenoses from aneurysm stenting is not fully understood. An 8mm cavernous carotid aneurysm with a wide neck was treated by a Neuroform stent first and by coils five weeks later. A comparison of the difference in morphology during this five-week period reveals the presence of intimal hyperplasia in the internal carotid artery, 1.3mm thick at the proximal end and 1mm at the distal end of the stent, and 1mm thick thrombus at the postero-inferior side of the an... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840973 Fri, 14 Jan 2011 00:00:00 +0100 4840973 http://www.medworm.com/index.php?rid=4840976&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310003115%2Fabstract%3Frss%3Dyes Abstract: The complete understanding of the mechanisms leading to the initiation, maintenance and self-termination of atrial fibrillation (AF) still is an unsolved challenge for cardiac electrophysiology. Studies in which AF has been induced have shown that electrophysiological and structural remodeling of the atria during the arrhythmia could play an important role in the transition from paroxysmal to persistent AF. However, to this day, the time course of the atrial remodeling along onward episodes of non-induced paroxysmal AF has not been investigated yet. In this work, a non-invasive method, based on the regularity estimation of AF through sample entropy (SampEn), has been used to assess the organization evolution along onward episodes of paroxysmal AF. Given that AF organization has b... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840976 Wed, 12 Jan 2011 00:00:00 +0100 4840976 http://www.medworm.com/index.php?rid=4840983&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002912%2Fabstract%3Frss%3Dyes Abstract: The purpose of this paper is to calculate the specific absorption rate (SAR) reduction in a muscle cube with metamaterial attachment. The finite-difference time-domain (FDTD) method has been used to evaluate the SAR in a realistic anatomically based model of the muscle cube. In this paper, we have designed the single-negative metamaterials from a periodic arrangement of split ring resonators (SRRs). By properly designing the structural parameter of the SRRs, the effective medium parameter can be tuned negative at the 900MHz and 1800MHz bands. Numerical results concerning the SAR values in the muscle cube in the presence of resonators exhibit significant SAR reduction. These results can provide useful information when designing safety-compliant mobile communication equipment. (Sou... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840983 Mon, 10 Jan 2011 00:00:00 +0100 4840983 http://www.medworm.com/index.php?rid=4840968&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002973%2Fabstract%3Frss%3Dyes Abstract: The rehabilitation engineering community is working towards the development of robotic devices that can assist during gait training of patients suffering from neurologic injuries such as stroke and spinal cord injuries (SCI). The field of robot assisted treadmill training has rapidly evolved during the last decade. The robotic devices can provide repetitive, systematic and prolonged gait training sessions. This paper presents a review of the treadmill based robotic gait training devices. An overview of design configurations and actuation methods used for these devices is provided. Training strategies designed to actively involve the patient in robot assisted treadmill training are studied. These training strategies assist the patient according to the level of disability and type ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4840968 Mon, 10 Jan 2011 00:00:00 +0100 4840968 http://www.medworm.com/index.php?rid=4683950&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002900%2Fabstract%3Frss%3Dyes This study aims to quantify and map the complexity of the EEG during PS, where complexity is measured as the degree of unpredictability resulting from local linear prediction. EEG activity was recorded with eyes closed (EC) and eyes open (EO) during resting and PS at 5, 10, and 15Hz in a group of 30 healthy subjects and in a case-report of a patient suffering from cerebral ischemia. The mean squared prediction error (MSPE) resulting from k-nearest neighbour local linear prediction was calculated in each condition as an index of EEG unpredictability. The linear or nonlinear nature of the system underlying EEG activity was evaluated quantifying MSPE as a function of the neighbourhood size during local linear prediction, and by surrogate data analysis as well. Unpredictability maps were obtai... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683950 Mon, 10 Jan 2011 00:00:00 +0100 4683950 http://www.medworm.com/index.php?rid=4683951&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002894%2Fabstract%3Frss%3Dyes Abstract: Despite the widespread use of porcine bone as a substitute for human bone in the development of surgical technique and the use of fixation devices, relatively few studies have reported on the mechanical behaviour of porcine long bones. Regional variation in the mechanical properties of cortical bone from porcine femora was investigated using three-point bending and cutting tests. Results were related to measurements of bone architecture and composition and Rutherford backscattering spectrometry (RBS) was used to calculate the calcium to phosphorus ratio. There was significant, but limited, regional variation in the strength of the femur with bone from the distal, posterior quadrant (241.4±10.43MPa) being significantly stronger than that of the lateral quadrant (162.3±17.96MPa).... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683951 Fri, 07 Jan 2011 00:00:00 +0100 4683951 http://www.medworm.com/index.php?rid=4683952&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002869%2Fabstract%3Frss%3Dyes Abstract: Package opening tasks have been identified as some of the most challenging that individuals need to perform to access food. There is little previous study of the 3D hand loading that is required to open these products. A novel load measuring device was used to characterise torque, squeeze and compression forces during the dynamic action of jar opening for young and older adults. The current study showed that the older adults used lower squeeze forces (86.1N vs. 95.4N) and higher compressive forces (26.9N vs. 25.2N) on the jar lid than younger adults. Older adults tended to apply loading to the jar lid slower (0.038Nm/s vs. 0.044Nm/s) and to open the jar at a slower rate (0.84Rad/s vs. 1.59Rad/s) than young adults whilst using a higher proportion of their maximal grip strength (40... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683952 Thu, 06 Jan 2011 00:00:00 +0100 4683952 http://www.medworm.com/index.php?rid=4683949&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002882%2Fabstract%3Frss%3Dyes Abstract: Articular cartilages and menisci are generally considered to be elastic in the published human knee models, and thus the fluid-flow dependent response of the knee has not been explored using finite element analysis. In the present study, the fluid pressure and site-specific collagen fiber orientation in the cartilages and menisci were implemented into a finite element model of the knee using fibril-reinforced modeling previously proposed for articular cartilage. The geometry of the knee was obtained from magnetic resonance imaging of a healthy young male. The bones were considered to be elastic due to their greater stiffness compared to that of the cartilages and menisci. The displacements obtained for fast ramp compression were essentially same as those for instantaneous compres... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683949 Thu, 06 Jan 2011 00:00:00 +0100 4683949 http://www.medworm.com/index.php?rid=4371773&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310003024%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4371773 Sat, 01 Jan 2011 00:00:00 +0100 4371773 http://www.medworm.com/index.php?rid=4683947&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002857%2Fabstract%3Frss%3Dyes Abstract: Closed intramedullary nailing is a common technique for treatment of femur and tibia fractures. The most challenging step in this procedure is the precise placement of the lateral screws that stabilize the fragmented bone.The present work concerns the development and the evaluation of a method to accurately identify in the 3D space the axes of the nail hole canals. A limited number of projection images are acquired around the leg with the help of a C-arm. On two of them, the locking hole entries are interactively selected and a rough localization of the hole axes is performed. Perpendicularly to one of them, cone-beam computed tomography (CBCT) reconstructions are produced. The accurate identification and localization of the hole axes are done by an identification of the centers ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683947 Thu, 23 Dec 2010 00:00:00 +0100 4683947 http://www.medworm.com/index.php?rid=4371774&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002845%2Fabstract%3Frss%3Dyes (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4371774 Thu, 23 Dec 2010 00:00:00 +0100 4371774 http://www.medworm.com/index.php?rid=4683948&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002870%2Fabstract%3Frss%3Dyes Abstract: The surgical devices for the treatment of degenerative disc disease are based on different concepts (rods for spine fusion, ROM-restricting or load-bearing devices for dynamic stabilization). In the present work, the effects of some stabilization systems on the biomechanics of the lumbar spine were investigated by means of a finite element model of the L2–L5 spine segment. Pedicular screws and stabilization devices were added at L4–L5. Different rods were considered: stainless steel, titanium, PEEK and the composite ostaPek. Two pedicular devices aimed at motion preservation were also considered: the FlexPLUS and the DSS. All models were loaded by using the hybrid protocol in flexion, extension, lateral bending and axial rotation. The spine biomechanics after implantation res... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683948 Wed, 22 Dec 2010 00:00:00 +0100 4683948 http://www.medworm.com/index.php?rid=4683945&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002808%2Fabstract%3Frss%3Dyes Abstract: While surface electromyography (SEMG) can accurately register electrical activity of muscles during gait, there are no methods to estimate muscular force non-invasively. To better understand the mechanical behavior of muscle, we evaluated surface muscle pressure (SMP) in conjunction with SEMG. Changes in anterior thigh radial pressure during isometric contractions and gait were registered by pressure sensors on the limb. During isometric knee extensions by a single subject, SMP waveforms correlated well with SEMG (r=0.97), and SEMG onsets preceded those of SMP by 35–40ms. SMP and SEMG signals were simultaneously recorded from the quadriceps of 10 healthy subjects during gait at speeds of 0.4, 0.8, 1.1, 1.4 and 2.2m/s. Muscle activity onset and cessation times were objectively d... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683945 Tue, 21 Dec 2010 00:00:00 +0100 4683945 http://www.medworm.com/index.php?rid=4683942&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002791%2Fabstract%3Frss%3Dyes Abstract: Disc swelling pressure (Pswell) facilitated by fixed charged density (FCD) of proteoglycans (Pfcd) and strain-dependent permeability (Pstrain) are of critical significance in the physiological functioning of discs. FCD of proteoglycans prevents any excessive matrix deformation by tissue stiffening, whereas strain-dependent permeability limits the rate of stress transfer from fluid to solid skeleton. To date, studies involving the modeling of FCD of proteoglycans and strain-dependent permeability have not been reported for the cervical discs. The current study objective is to compare the relative contributions of strain-dependent permeability and FCD of proteoglycans in predicting cervical disc biomechanics. Three-dimensional finite element models of a C5–C6 segment with three d... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683942 Fri, 17 Dec 2010 00:00:00 +0100 4683942 http://www.medworm.com/index.php?rid=4683946&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002833%2Fabstract%3Frss%3Dyes Abstract: The ligamentous spinal column buckles under compressive loads of even less than 100N. Experimental results showed that under the follower load constraint, the ligamentous lumbar spine can sustain large compressive loads without buckling, while at the same time maintaining its flexibility reasonably well. The purpose of this study was to investigate the feasibility of follower loads produced by spinal muscles in the lumbar spine in a quiet standing posture. A three-dimensional static model of the lumbar spine incorporating 232 back muscles was developed and utilized to perform the optimization analysis in order to find the muscle forces, and compressive follower loads (CFLs) along optimum follower load paths (FLPs). The effect of increasing external loads on CFLs was also investig... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683946 Thu, 16 Dec 2010 00:00:00 +0100 4683946 http://www.medworm.com/index.php?rid=4683943&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002778%2Fabstract%3Frss%3Dyes Abstract: Although the surface electroenterogram (EEnG) is a weak signal contaminated by strong physiological interference, such as ECG and respiration, abdominal surface recordings of the EEnG could provide a non-invasive method of studying intestinal activity. The goal of this work was to develop a modular, active, low-cost and easy-to-use sensor to obtain a direct estimation of the Laplacian of the EEnG on the abdominal surface in order to enhance the quality of bipolar surface monitoring of intestinal activity. The sensor is made up of a set of 3 concentric dry Ag/AgCl ring electrodes and a battery-powered signal-conditioning circuit. Each section is etched on a different printed circuit board (PCB) and the sections are joined to each other by surface mount technology connectors. This ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683943 Thu, 16 Dec 2010 00:00:00 +0100 4683943 http://www.medworm.com/index.php?rid=4683944&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331000281X%2Fabstract%3Frss%3Dyes In this study, the effects of the presence of the torsional load in addition to the compressive load on the predicted stresses of the fracture fixation bone-plate system are examined at different healing stages. The effects on the stress on the fracture site when using contacted and non-contacted bone-plate systems are also studied. The FE modelling results indicate that the torsional load has significant effects on the resultant stress on the fracture fixation bone-plate system, which should be taken into consideration during the design and the analysis. The results also show that the stress shielding at the fracture site decreases significantly when using FG bone-plates compared to Ti alloy or SS bone-plates. The presence of a gap between the bone and the plate results in a remarkable re... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683944 Mon, 13 Dec 2010 00:00:00 +0100 4683944 http://www.medworm.com/index.php?rid=4683941&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331000278X%2Fabstract%3Frss%3Dyes This study investigated the sensitivity of the five sEMG measures during the force gradation process. Tissue and electrode filtering effects were further evaluated using a sEMG model. Subjects (N=8) performed isometric elbow flexion contractions from 0 to 100% MVC. The sEMG signals from the biceps brachii were recorded simultaneously with force. The basic building block of the sEMG model was the detection of single fibre action potentials (SFAPs) through a homogeneous, equivalent isotropic, infinite volume conduction medium. The SFAPs were summed to generate single motor unit action potentials. The physiologic properties from a well-known muscle model and motor unit recruitment and firing rate schemes were combined to generate synthetic sEMG signals. The following pattern classification me... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683941 Mon, 13 Dec 2010 00:00:00 +0100 4683941 http://www.medworm.com/index.php?rid=4683940&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002754%2Fabstract%3Frss%3Dyes This study suggests that porous coated metal percutaneous implants are at a significantly lower risk of infection when compared to smooth metal implants. The smooth surface percutaneous implants were inadequate in allowing a long-term seal to develop with the soft tissue, thus increasing vulnerability to the migration of infecting microorganisms. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683940 Mon, 13 Dec 2010 00:00:00 +0100 4683940 http://www.medworm.com/index.php?rid=4683938&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002705%2Fabstract%3Frss%3Dyes Abstract: The investigation of patellar tendon reflex involves development of a reflex hammer holder, kinematic data collection and analysis of patellar reflex responses using motion analysis techniques. The main aim of this research is to explore alternative means of assessing reflexes as a part of routine clinical diagnosis. The motion analysis system was applied to provide quantitative data which is a more objective measure of the patellar tendon reflex. Kinematic data was collected from 28 males and 22 females whilst subjected to a knee jerk test. Further analysis of kinematic data was performed to predict relationships which might affect the patellar tendon reflex. All subjects were seated on a high stool with their legs hanging freely within the capture volume of the motion analysis ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4683938 Mon, 13 Dec 2010 00:00:00 +0100 4683938 http://www.medworm.com/index.php?rid=4591825&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002742%2Fabstract%3Frss%3Dyes In conclusion, our new endoscope successfully provided a detailed view of the placental vessels in vivo. The results are promising for future TTTS laser surgery. (Source: Medical Engineering and Physics) Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591825 Mon, 13 Dec 2010 00:00:00 +0100 4591825 http://www.medworm.com/index.php?rid=4591821&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002699%2Fabstract%3Frss%3Dyes Abstract: Electrical impedance spectroscopy offers many applications in the medical field due the fast response, non-invasiveness and low cost. One promising area is the use of this method for diagnostics. This paper describes the design and experimental evaluation of a multifrequencial complex bioimpedance analyzer. Impedance amplitude and phase were calculated using Discrete Fourier Transform (DFT) and high frequency signals were measured with undersampling. The prototype was able to measure values from 1Ω to 50kΩ (frequency range from 50Hz to 500kHz). The accuracy of the technique was compared with a commercial equipment. The analysis of passive components resulted in a mean error of 2.9% for the magnitude and 0.69 degrees for the phase. Besides, an initial study for head and neck can... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591821 Mon, 13 Dec 2010 00:00:00 +0100 4591821 http://www.medworm.com/index.php?rid=4591824&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002730%2Fabstract%3Frss%3Dyes Abstract: In order to design a good cementless femoral implant many requirements need to be fulfilled. For instance, the range of micromotions at the bone–implant interface should not exceed a certain threshold and a good ratio between implant–bone stiffness that does not cause bone resorption, needs to be ensured. Stiff implants are known to evoke lower interface micromotions but at the same time they may cause extensive resorption of the surrounding bone. Composite stems with reduced stiffness give good remodeling results but implant flexibility is likely to evoke high micromotions proximally. Finding a good balance between these incompatible design goals is very challenging. The current study proposes a finite element methodology that employs subsequent ingrowth and remodeling simul... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591824 Fri, 10 Dec 2010 00:00:00 +0100 4591824 http://www.medworm.com/index.php?rid=4591820&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002560%2Fabstract%3Frss%3Dyes This article used a statistical method to analyze the altered stride interval in patients with ALS. We first estimated the probability density functions (PDFs) of stride interval from the outlier-processed gait rhythm time series, by using the nonparametric Parzen-window approach. Based on the PDFs estimated, the mean of the left-foot stride interval and the modified Kullback–Leibler divergence (MKLD) can be computed to serve as dominant features. In the classification experiments, the least squares support vector machine (LS-SVM) with Gaussian kernels was applied to distinguish the stride patterns in ALS patients. According to the results obtained with the stride interval time series recorded from 16 healthy control subjects and 13 patients with ALS, the key findings of the present stud... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591820 Mon, 06 Dec 2010 00:00:00 +0100 4591820 http://www.medworm.com/index.php?rid=4591819&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002547%2Fabstract%3Frss%3Dyes The objective of our study was to develop and validate an apparatus, that allows to perform intraoperative in vivo measurements to determine both the applied force and the resulting motion in three dimensional space. The proposed setup combines force measurement with an instrumented distractor and motion tracking with an optoelectronic system. As the orientation of the applied force and the three dimensional motion is known, not only force–displacement, but also moment-angle relations could be determined. The validation was performed using three cadaveric lumbar ovine spines. The lateral bending stiffness of two motion segments per specimen was determined with the proposed concept and compared with the stiffness acquired on a spinal loading simulator which was considered to be gold stand... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591819 Mon, 06 Dec 2010 00:00:00 +0100 4591819 http://www.medworm.com/index.php?rid=5103233&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002535%2Fabstract%3Frss%3Dyes Abstract: Left–right symmetry breaking in the mammalian embryo is believed to occur in a transient embryonic structure, the node: rotational motion of cilia within this structure creates a leftward flow of liquid that is the first asymmetric event observed. A hypothesis, often referred to as the “two-cilia” hypothesis, proposes that the node contains two kinds of primary cilia: motile cilia, driven by motor proteins, that rotate clockwise generating the leftward flow and passive cilia that act as mechano-sensors, reacting mechanically to the emerging flow. The exact mechanism that underlies the initial breaking of symmetry remains unclear, in spite of several studies that have attempted to elucidate the processes involved. In this paper, we present two computational models to (i) sim... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=5103233 Thu, 02 Dec 2010 00:00:00 +0100 5103233 http://www.medworm.com/index.php?rid=4591823&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002717%2Fabstract%3Frss%3Dyes Abstract: Most of the knowledge on falls of older persons has been obtained from oral reports that might be biased in many ways. Fall simulations are widely used to gain insight into circumstances of falls, but the results, at least concerning fall detection, are not convincing. Variation of acceleration and maximum jerk of 5 real-world backward falls of 4 older persons (mean age 68.8 years) were compared to the corresponding signals of simulated backward falls by 18 healthy students. Students were instructed to “fall to the back as if you were a frail old person” during experiment 1. In experiment 2, students were instructed not to fall, if possible, when released from a backward lean. Data acquisition was performed using a tri-axial acceleration sensor. In experiment 1, there was sig... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591823 Thu, 02 Dec 2010 00:00:00 +0100 4591823 http://www.medworm.com/index.php?rid=4591817&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002511%2Fabstract%3Frss%3Dyes Abstract: As predicted by the Pennes equation, skin blood flow is a major contributor to the removal of heat from an external heat source. This protects the skin from erythema and burns. But, for a person in a thermally neutral room, the skin is normally much cooler than arterial blood. Therefore, if skin blood flow (BF) increases, it should initially warm the skin paradoxically. To examine this phenomenon, 10 young male and female subjects participated in a series of experiments to examine the contribution of skin blood flow in the initial warming the skin after the application of local heat. Heat flow was measured by the use of a thermode above the brachioradialis muscle. The thermode was warmed by constant temperature water at 44°C entering the thermode at a water flow rate of 100cm3/m... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591817 Wed, 01 Dec 2010 00:00:00 +0100 4591817 http://www.medworm.com/index.php?rid=4591827&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002572%2Fabstract%3Frss%3Dyes Abstract: Accurate in vivo estimation of muscle volume is important as it indicates the amount of power a muscle can produce. By tracking muscle volume changes in vivo, a muscle's response to disease or rehabilitation training can be quantified. The purpose of this study was to validate the use of imaging ultrasound to estimate the volume of a small muscle, specifically the First Dorsal Interosseous (FDI) muscle. The perimeter of the FDI was imaged using ultrasound in 22 cadaver hands. For each FDI, serial cross-sectional areas were determined by manual digitization, volumes were then estimated using the Cavalieri principle. The muscles were then dissected from the cadavers, and muscle volume was determined via the water displacement method. The water displacement measures of muscle volume... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591827 Mon, 29 Nov 2010 00:00:00 +0100 4591827 http://www.medworm.com/index.php?rid=4591822&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002729%2Fabstract%3Frss%3Dyes Abstract: Murmur is the result of various heart abnormalities. A new robust approach for separation of murmur from heart sound has been suggested in this article. Singular spectrum analysis (SSA) has been adapted to the changes in the statistical properties of the data and effectively used for detection of murmur from single-channel heart sound (HS) signals. Incorporating a cleverly selected a priori within the SSA reconstruction process, results in an accurate separation of normal HS from the murmur segment. Another contribution of this work is selection of the correct subspace of the desired signal component automatically. In addition, the subspace size can be identified iteratively. A number of HS signals with murmur have been processed using the proposed adaptive SSA (ASSA) technique a... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591822 Mon, 29 Nov 2010 00:00:00 +0100 4591822 http://www.medworm.com/index.php?rid=4591818&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002559%2Fabstract%3Frss%3Dyes Abstract: Stapedial annular ligament (SAL) provides a sealed but mobile boundary between the stapes footplate and oval window bony wall. Mechanical properties of the SAL affect the transmission of ossicular movement into the cochlea in sound conduction. However, the mechanical properties of this tissue have never been investigated due to its complexity. In this paper, we report measurement of the viscoelastic properties of SAL on human cadaver temporal bones using a micro-material testing system with digital image correlation analysis. The measured load–deformation relations of SAL samples were converted into shear stress–shear strain relationship, stress relaxation function, and ultimate shear stress and shear strain of the SAL. The hyperelastic Ogden model was used to describe consti... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591818 Mon, 29 Nov 2010 00:00:00 +0100 4591818 http://www.medworm.com/index.php?rid=4591812&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331000247X%2Fabstract%3Frss%3Dyes Abstract: Effectiveness of orthotic treatment for scoliosis depends on how much time and how well the orthosis is worn. Questionnaires and clinical judgment are subjective methods to wear compliance. Even though using a temperature sensor can objectively record how long the orthosis has been used, it may not be able to answer the orthosis effectiveness without knowing the wear tightness. Custom made thoracolumbosacral orthoses (TLSO) were instrumented with low power wireless data acquisition systems to measure the time and loads imposed by the pressure pad during daily activities. Force measurements were recorded at 1sample/min and the system was able to record data up to 4 months without patient-involvement. Ten subjects (9F, 1M), age between 9 and 13.5 years, average 11.6±1.3 years, who... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591812 Mon, 29 Nov 2010 00:00:00 +0100 4591812 http://www.medworm.com/index.php?rid=4591816&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS135045331000250X%2Fabstract%3Frss%3Dyes In this study we numerically investigate pulsatile blood flow in a simplified model of the aorta (curved pipe) with coexisting coarctation of the aorta and aortic stenosis. Three severities of aortic stenoses (0.61cm2, 1.0cm2 and 1.5cm2) coexisting with aortic coarctations (50%, 75% and 90% by area) are investigated. An experimentally validated numerical model from literature is used and baseline results are validated against it. To ensure having a physiologically relevant model using this geometry, flow properties are set so that the Dean number falls in the physiological range for the aorta. The results show that the coexistence of these pathologies significantly modifies the flow in a curved pipe. The maximal velocity is shifted towards the outer wall and can reach values as high as 5m/... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591816 Wed, 24 Nov 2010 00:00:00 +0100 4591816 http://www.medworm.com/index.php?rid=4591826&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002523%2Fabstract%3Frss%3Dyes This study describes the development and evaluation of a platform for the investigation of the human tactile ability. Specifically, it enables precise and reproducible application of time-varying 3D force stimuli to the skin of an immobilized human limb. We proceeded in the following steps: (1) programming a low-cost haptic interface to apply time-varying 3D force stimuli to a fixed rigid target, (2) implementing a combined feed-forward/feedback controller to improve the platform's precision and reliability in force stimulation, (3) determining the optimal tuning of the control loop parameters and (4) evaluating the system's performances when applying time-varying 3D force stimuli to an immobilized human finger pad. The system's performances were evaluated in terms of the accuracy and repe... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591826 Mon, 22 Nov 2010 00:00:00 +0100 4591826 http://www.medworm.com/index.php?rid=4591814&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002444%2Fabstract%3Frss%3Dyes Abstract: Background: The mechanical characterization of prostate tissue has not received much attention and is often disconnected from the clinic, where samples are readily attained.Methods: We developed a spherical indenter for the clinic to generate force–displacement data from ex vivo prostate tissue. Indentation velocity, depth, and sphere diameter, and four means of estimating elastic modulus (EM) were validated. EM was then estimated for 26 prostate specimens obtained via prostatectomy and 6 samples obtained from autopsy. Prostatectomy prostates were evaluated clinically upon digital rectal exam and pathologically post-extirpation.Findings: Whole-mount measurements yielded median EM of 43.2kPa (SD=59.8kPa). Once sliced into cross-sections, median EM for stage T2 and T3 glands were... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591814 Mon, 22 Nov 2010 00:00:00 +0100 4591814 http://www.medworm.com/index.php?rid=4371775&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310001694%2Fabstract%3Frss%3Dyes Abstract: The aim of the study is to characterise mechanical properties of human abdominal fascia according to its direction of loading and localization. The one-dimensional tensile behaviour of human abdominal fascia and its orthotropy has been studied experimentally using human umbilical (UF) and transversalis fascia (FT). The specimens have been cut and stretched parallel and orthogonal to the main fibre bundles. 90 specimens 10mm wide and up to 70mm long have been tested. The following mechanical parameters, characterising tensile properties of human abdominal fascia, have been calculated from the obtained stress–stretch ratio curves: maximal stress , stretch ratio at maximal stress λTmax, maximal stretch ratio at failure λmax, and a secant modulus E(i). The tissue strips obtained ... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4371775 Mon, 22 Nov 2010 00:00:00 +0100 4371775 http://www.medworm.com/index.php?rid=4591815&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310002432%2Fabstract%3Frss%3Dyes Abstract: Cementless hip implants have some osteolysis, stress shielding, and/or revision problems while the cemented ones have cement fracture problems. To overcome these problems, a new concept of implant fixation using a sleeve between the implant and the bone is proposed. This is a cementless fixation using a sleeve in place of the cement with a press-fit stem.The sleeved implant fixation is compared with the conventional cemented fixation by measuring the bone volume fraction and interface strength in a rat model. The tapered implant was manufactured using a stainless-steel Kirschner-wire with a diameter of 1.6mm, and PEEK (polyetheretherketone) was used for the sleeve. The Sprague–Dawley rats had implantations in their bilateral diaphyseal cut femurs using cemented and sleeved fixa... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4591815 Fri, 19 Nov 2010 00:00:00 +0100 4591815 http://www.medworm.com/index.php?rid=4371776&cid=s_35854_169_f&fid=35854&url=http%3A%2F%2Fwww.medengphys.com%2Farticle%2FPIIS1350453310001797%2Fabstract%3Frss%3Dyes Abstract: The BION (Bionic Neuron) is a single channel implantable neurostimulator of unique design that can be delivered by injection. The development of the BION injectable neurostimulators exemplifies a challenging, but well posed medical design problem addressed with a successful strategy for prioritizing and resolving the biomedical and technological challenges. Though some performance requirements required post-evaluation revision, all fundamental goals were realized. A small number of significant design corrections occurred because the device requirements did not include the full scope of environmental demands. The design has spawned a number of variants optimized for diverse biomedical applications, and its clinical applications continue to evolve. The BION development history demo... Medical Engineering and Physics journals http://www.medworm.com/rss/comments.php?id=4371776 Fri, 19 Nov 2010 00:00:00 +0100 4371776