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A Genetic Algorithm Based Multi-Objective Shape Optimization Scheme for Cementless Femoral Implant
The objective of this study was to develop a novel multi-objective custom-based shape optimization scheme for cementless femoral implant by integrating finite element (FE) analysis and a multi-objective genetic algorithm (GA). The FE model of a proximal femur was based on a subject-specific CT-scan dataset. Eighteen parameters describing the nature of four key sections of the implant were identified as design variables. Two objective functions, one based on implant-bone interface failure criterion, and the other based on resorbed proximal bone mass fraction (BMF), were formulated. The results predicted by the two objective...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Computational Simulation of the Adaptive Capacity of Vein Grafts in Response to Increased Pressure
Vein maladaptation, leading to poor long-term patency, is a serious clinical problem in patients receiving coronary artery bypass grafts (CABGs) or undergoing related clinical procedures that subject veins to elevated blood flow and pressure. We propose a computational model of venous adaptation to altered pressure based on a constrained mixture theory of growth and remodeling (G&R). We identify constitutive parameters that optimally match biaxial data from a mouse vena cava, then numerically subject the vein to altered pressure conditions and quantify the extent of adaptation for a biologically reasonable set of bounds fo...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Characterizing the Importance of Free Space in the Numerical Human Body Models
The geometric fidelity of the inner organs on finite-element model (FEM) of the human body and the choice to use discontinuous mesh engender the appearance of empty spaces that do not reflect the real-life situation of human body cavities. The aim of this study is to assess the influence of these empty spaces on the behavior of a simplified FEM built with three different structures in interaction which properties are relevant with the abdominal cavity. This FEM is made up of a large sphere (peritoneum) containing two hemispheres (liver and spleen). The space between peritoneum and inner organs was defined with two differen...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Decreased Elastic Energy Storage, Not Increased Material Stiffness, Characterizes Central Artery Dysfunction in Fibulin-5 Deficiency Independent of Sex
Central artery stiffness has emerged over the past 15 years as a clinically significant indicator of cardiovascular function and initiator of disease. Loss of elastic fiber integrity is one of the primary contributors to increased arterial stiffening in aging, hypertension, and related conditions. Elastic fibers consist of an elastin core and multiple glycoproteins; hence defects in any of these constituents can adversely affect arterial wall mechanics. In this paper, we focus on mechanical consequences of the loss of fibulin-5, an elastin-associated glycoprotein involved in elastogenesis. Specifically, we compared the bia...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

A Thick-Walled Fluid–Solid-Growth Model of Abdominal Aortic Aneurysm Evolution: Application to a Patient-Specific Geometry
We propose a novel thick-walled fluid–solid-growth (FSG) computational framework for modeling vascular disease evolution. The arterial wall is modeled as a thick-walled nonlinearly elastic cylindrical tube consisting of two layers corresponding to the media-intima and adventitia, where each layer is treated as a fiber-reinforced material with the fibers corresponding to the collagenous component. Blood is modeled as a Newtonian fluid with constant density and viscosity; no slip and no-flux conditions are applied at the arterial wall. Disease progression is simulated by growth and remodeling (G&R) of the load bearing cons...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Unidirectional Cell Crawling Model Guided by Extracellular Cues
Cell migration is a highly regulated and complex cellular process to maintain proper homeostasis for various biological processes. Extracellular environment was identified as the main affecting factors determining the direction of cell crawling. It was observed experimentally that the cell prefers migrating to the area with denser or stiffer array of microposts. In this article, an integrated unidirectional cell crawling model was developed to investigate the spatiotemporal dynamics of unidirectional cell migration, which incorporates the dominating intracellular biochemical processes, biomechanical processes and the prope...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Simulation of Occupant Response in Space Capsule Landing Configurations With Suit Hardware
The purpose of this study was to compare the response of the total human model for safety (THUMS) human body finite element model (FEM) to experimental postmortem human subject (PMHS) test results and evaluate possible injuries caused by suit ring elements. Experimental testing evaluated the PMHS response in frontal, rear, side, falling, and spinal impacts. The THUMS was seated in a rigid seat that mirrored the sled buck used in the experimental testing. The model was then fitted with experimental combinations of neck, shoulder, humerus and thigh rings with a five-point restraint system. Experimental seat acceleration data...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Immersive Visualization for Enhanced Computational Fluid Dynamics Analysis
We present a semi-automatic workflow for the import, processing, rendering, and stereoscopic visualization of high resolution, patient-specific imaging data, and CFD results in an IVE. Versatility of the workflow is highlighted with current clinical sequelae known to be influenced by adverse hemodynamics to illustrate potential clinical utility. (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Assessing the Local Mechanical Environment in Medial Opening Wedge High Tibial Osteotomy Using Finite Element Analysis
This study demonstrates the benefits of using image-based FE modeling and bone theory to fine-tune HTO implant design. (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Rotational Acceleration, Brain Tissue Strain, and the Relationship to Concussion
The mechanisms of concussion have been investigated by many researchers using a variety of methods. However, there remains much debate over the relationships between head kinematics from an impact and concussion. This review presents the links between research conducted in different disciplines to better understand the relationship between linear and rotational acceleration and brain strains that have been postulated as the root cause of concussion. These concepts are important when assigning performance variables for helmet development, car design, and protective innovation research. (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Simulations Reveal Adverse Hemodynamics in Patients With Multiple Systemic to Pulmonary Shunts
In this study, we hypothesize that multiple shunts may lead to undesirable flow competition, resulting in increased residence time (RT) and elevated risk of thrombosis, as well as pulmonary overcirculation. Computational fluid dynamics-based multiscale simulations were performed to compare a range of shunt configurations and systematically quantify flow competition, pulmonary circulation, and other clinically relevant parameters. In total, 23 cases were evaluated by systematically changing the PDA/CS diameter, pulmonary vascular resistance (PVR), and MBTS position and compared by quantifying oxygen delivery (OD) to the sys...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

Enhanced Targeted Drug Delivery Through Controlled Release in a Three-Dimensional Vascular Tree
“Controlled particle release and targeting” is a technique using particle release score map (PRSM) and transient particle release score map (TPRSM) via backtracking to determine optimal drug injection locations for achieving an enhanced target efficiency (TE). This paper investigates the possibility of targeting desired locations through an idealized but complex three-dimensional (3D) vascular tree geometry under realistic hemodynamic conditions by imposing a Poiseuille velocity profile and a Womersley velocity profile derived from cine phase contrast magnetic resonance imaging (MRI) data for steady and pulsatile simul...
Source: Journal of Biomechanical Engineering - January 29, 2015 Category: Biomedical Engineering Source Type: research

New Editorial Board
Publication date: February 2015 Source:IRBM, Volume 36, Issue 1 Author(s): Maximilien Vermandel , Christine Toumoulin (Source: IRBM)
Source: IRBM - January 29, 2015 Category: Biomedical Engineering Source Type: research

Call for papers for a Special Issue on Medical Image Analysis for Computer Aided Diagnosis
Publication date: February 2015 Source:IRBM, Volume 36, Issue 1 Author(s): Khalifa Djemal , Su Ruan , Christine Toumoulin (Source: IRBM)
Source: IRBM - January 29, 2015 Category: Biomedical Engineering Source Type: research

Multi-Focus Raw Bayer Pattern Image Fusion for Single-Chip Camera
Abstract In this paper, an efficient patch-based image fusion approach for raw images of single-chip imaging devices incorporated with the Bayer CFA pattern is presented. The multi-source raw Bayer pattern images are firstly parted into half overlapped patches. Then, the patches with maximum clarity measurement defined for raw Bayer pattern image are selected as the fused patches. Next, all the fused local patches are merged with weighted average method in order to reduce the blockness effect of fused raw Bayer pattern image. Finally, the real color fused image is obtained by gradient based demosaicing technology...
Source: Sensing and Imaging - January 28, 2015 Category: Biomedical Engineering Source Type: research

Distributed Fronthaul Compression and Joint Signal Recovery in Cloud-RAN
The cloud radio access network (C-RAN) is a promising network architecture for future mobile communications, and one practical hurdle for its large scale implementation is the stringent requirement of high capacity and low latency fronthaul connecting the distributed remote radio heads (RRH) to the centralized baseband pools (BBUs) in the C-RAN. To improve the scalability of C-RAN networks, it is very important to take the fronthaul loading into consideration in the signal detection, and it is very desirable to reduce the fronthaul loading in C-RAN systems. In this paper, we consider uplink C-RAN systems and we propose a d...
Source: IEEE Transactions on Signal Processing - January 27, 2015 Category: Biomedical Engineering Source Type: research

Compressive Phase Retrieval via Generalized Approximate Message Passing
In phase retrieval, the goal is to recover a signal $ { mbi {x}}in BBC ^{N}$ from the magnitudes of linear measurements $ { mbi {Ax}}in BBC ^{M}$. While recent theory has established that $Mapprox 4N$ intensity measurements are necessary and sufficient to recover generic $ { mbi {x}}$, there is great interest in reducing the number of measurements through the exploitation of sparse $ { mbi {x}}$, which is known as compressive phase retrieval. In this work, we detail a novel, probabilistic approach to compressive phase retrieval based on the generalized approximate message passing (GAMP) algorithm. We then present a numeric...
Source: IEEE Transactions on Signal Processing - January 27, 2015 Category: Biomedical Engineering Source Type: research

Compressive Two-Dimensional Harmonic Retrieval via Atomic Norm Minimization
This paper is concerned with estimation of two-dimensional (2-D) frequencies from partial time samples, which arises in many applications such as radar, inverse scattering, and super-resolution imaging. Suppose that the object under study is a mixture of $r$ continuous-valued 2-D sinusoids. The goal is to identify all frequency components when we only have information about a random subset of $n$ regularly spaced time samples. We demonstrate that under some mild spectral separation condition, it is possible to exactly recover all frequencies by solving an atomic norm minimization program, as long as the sample complexity e...
Source: IEEE Transactions on Signal Processing - January 27, 2015 Category: Biomedical Engineering Source Type: research

Deterministic Constructions of Binary Measurement Matrices From Finite Geometry
Deterministic constructions of measurement matrices in compressed sensing (CS) are considered in this paper. The constructions are inspired by the recent discovery of Dimakis, Smarandache and Vontobel which says that parity-check matrices of good low-density parity-check (LDPC) codes can be used as provably good measurement matrices for compressed sensing under $ell_1$-minimization. The performance of the proposed binary measurement matrices is mainly theoretically analyzed with the help of the analyzing methods and results from (finite geometry) LDPC codes. Particularly, several lower bounds of the spark (i.e., the smalle...
Source: IEEE Transactions on Signal Processing - January 27, 2015 Category: Biomedical Engineering Source Type: research

Dictionary Learning Over Distributed Models
In this paper, we consider learning dictionary models over a network of agents, where each agent is only in charge of a portion of the dictionary elements. This formulation is relevant in Big Data scenarios where large dictionary models may be spread over different spatial locations and it is not feasible to aggregate all dictionaries in one location due to communication and privacy considerations. We first show that the dual function of the inference problem is an aggregation of individual cost functions associated with different agents, which can then be minimized efficiently by means of diffusion strategies. The collabo...
Source: IEEE Transactions on Signal Processing - January 27, 2015 Category: Biomedical Engineering Source Type: research

Monotonic Mean-Squared Convergence Conditions for Random Pairwise Consensus Synchronization in Wireless Networks
Time synchronization is important for a variety of applications in wireless networks including scheduling communication resources, interference avoidance, and data fusion. This paper analyzes the problem of synchronizing nodes in a time-division-duplexed wireless network via consensus methods using only acknowledged message exchanges over existing network traffic. The nodes are assumed to communicate synchronization information randomly and asymmetrically, reflecting the random nature of the timing and the source of synchronization information gleaned from or embedded in existing network traffic. The synchronization method...
Source: IEEE Transactions on Signal Processing - January 27, 2015 Category: Biomedical Engineering Source Type: research

Bayesian Sequential Parameter Estimation by Cognitive Radar With Multiantenna Arrays
In this paper we consider the problem of Bayesian sequential parameter estimation of extended targets for cognitive radar with multi-antenna arrays using adaptive waveforms. The target is modeled as a complex Gaussian random process. Using iterative waveform transmission, the cognitive radar estimates the target's characteristic parameters and updates its probabilistic model based on new measurements. The adaptive waveform is designed by minimizing the conditional entropy from the posterior density of the model parameters. We analyze the performance of the developed Bayesian sequential estimation algorithm and derive expre...
Source: IEEE Transactions on Signal Processing - January 27, 2015 Category: Biomedical Engineering Source Type: research

Optimal Stochastic Coordinated Beamforming for Wireless Cooperative Networks With CSI Uncertainty
Transmit optimization and resource allocation for wireless cooperative networks with channel state information (CSI) uncertainty are important but challenging problems in terms of both the uncertainty modeling and performance optimization. In this paper, we establish a generic stochastic coordinated beamforming (SCB) framework that provides flexibility in the channel uncertainty modeling, while guaranteeing optimality in the transmission strategies. We adopt a general stochastic model for the CSI uncertainty, which is applicable for various practical scenarios. The SCB problem turns out to be a joint chance constrained pro...
Source: IEEE Transactions on Signal Processing - January 27, 2015 Category: Biomedical Engineering Source Type: research

IEEE Transactions on Biomedical Circuits and Systems information for authors
(Source: IEEE Transactions on Biomedical Circuits and Systems)
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

IEEE Transactions on Biomedical Circuits and Systems society information
(Source: IEEE Transactions on Biomedical Circuits and Systems)
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

A Single-Chip 32-Channel Analog Beamformer With 4-ns Delay Resolution and 768-ns Maximum Delay Range for Ultrasound Medical Imaging With a Linear Array Transducer
A single-chip 32-channel analog beamformer is proposed. It achieves a delay resolution of 4 ns and a maximum delay range of 768 ns. It has a focal-point based architecture, which consists of 7 sub-analog beamformers (sub-ABF). Each sub-ABF performs a RX focusing operation for a single focal point. Seven sub-ABFs perform a time-interleaving operation to achieve the maximum delay range of 768 ns. Phase interpolators are used in sub-ABFs to generate sampling clocks with the delay resolution of 4 ns from a low frequency system clock of 5 MHz. Each sub-ABF samples 32 echo signals at different times into sampling capacitors, whi...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

A Vestibular Prosthesis With Highly-Isolated Parallel Multichannel Stimulation
This paper presents an implantable vestibular stimulation system capable of providing high flexibility independent parallel stimulation to the semicircular canals in the inner ear for restoring three-dimensional sensation of head movements. To minimize channel interaction during parallel stimulation, the system is implemented with a power isolation method for crosstalk reduction. Experimental results demonstrate that, with this method, electrodes for different stimulation channels located in close proximity (${<} 2$ mm) can deliver current pulses simultaneously with minimum inter-channel crosstalk. The design features a...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

A Remotely Powered Implantable Biomedical System With Location Detector
An universal remote powering and communication system is presented for the implantable medical devices. The system be interfaced with different sensors or actuators. A mobile external unit controls the operation of the implantable chip and reads the sensor's data. A locator system is proposed to align the mobile unit with the implant unit for the efficient magnetic power transfer. The location of the implant is detected with 6 mm resolution from the rectified voltage level at the implanted side. The rectified voltage level is fedback to the mobile unit to adjust the magnetic field strength and maximize the efficienc...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

Respiration Detection Chip With Integrated Temperature-Insensitive MEMS Sensors and CMOS Signal Processing Circuits
An airflow sensing chip, which integrates MEMS sensors with their CMOS signal processing circuits into a single chip, is proposed for respiration detection. Three micro-cantilever-based airflow sensors were designed and fabricated using a 0.35 $mu$m CMOS/MEMS 2P4M mixed-signal polycide process. Two main differences were present among these three designs: they were either metal-covered or metal-free structures, and had either bridge-type or fixed-type reference resistors. The performances of these sensors were measured and compared, including temperature sensitivity and airflow sensitivity. Based on the measured results, th...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

A Home Sleep Apnea Screening Device With Time-Domain Signal Processing and Autonomous Scoring Capability
Current solutions of sleep apnea diagnosis require the patient to undergo overnight studies at a specialized sleep laboratory. Due to such inconvenience and high cost, millions of sleep apnea patients remain undiagnosed and thus untreated. Based on a micro-electro-mechanical systems (MEMS) sensor and an effective apnea detection algorithm, we propose a low-cost single-channel apnea screening solution applicable in the comfort of patients' homes. A prototype device was designed and assembled including a MEMS sensor for measuring the patient's nasal air flows, and a time-domain signal processing IC for apnea de...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

Neuronal Synapse as a Memristor: Modeling Pair- and Triplet-Based STDP Rule
We propose a new memristive model for the neuronal synapse based on the spike-timing-dependent plasticity (STDP) protocol, considering both long-term and short-term plasticity in the synapse. Higher-order behavior is modeled by a memristor with adaptive thresholds, which realizes the well-established suppression principle of Froemke. We assume a mechanism of variable thresholds adapting to synaptic potentiation (LTP) and depression (LTD), which reproduces the refractory time in the weight modification. The corresponding dynamical process is governed by a set of ordinary differential equations. Interestingly, the Froemke&#x...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

${rm A}~6~{mu{rm W}}$ per Channel Analog Biomimetic Cochlear Implant Processor Filterbank Architecture With Across Channels AGC
A new analog cochlear implant processor filterbank architecture of increased biofidelity, enhanced across-channel contrast and very low power consumption has been designed and prototyped. Each channel implements a biomimetic, asymmetric bandpass-like One-Zero-Gammatone-Filter (OZGF) transfer function, using class-AB log-domain techniques. Each channel's quality factor and suppression are controlled by means of a new low power Automatic Gain Control (AGC) scheme which is coupled across the neighboring channels and emulates lateral inhibition (LI) phenomena in the auditory system. Detailed measurements from a five-cha...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

An 81.6 $mu {rm W}$ FastICA Processor for Epileptic Seizure Detection
To improve the performance of epileptic seizure detection, independent component analysis (ICA) is applied to multi-channel signals to separate artifacts and signals of interest. FastICA is an efficient algorithm to compute ICA. To reduce the energy dissipation, eigenvalue decomposition (EVD) is utilized in the preprocessing stage to reduce the convergence time of iterative calculation of ICA components. EVD is computed efficiently through an array structure of processing elements running in parallel. Area-efficient EVD architecture is realized by leveraging the approximate Jacobi algorithm, leading to a 77.2% area reducti...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

A Compact and Autoclavable System for Acute Extracellular Neural Recording and Brain Pressure Monitoring for Humans
One of the most difficult tasks for the surgeon during the removal of low-grade gliomas is to identify as precisely as possible the borders between functional and non-functional brain tissue with the aim of obtaining the maximal possible resection which allows to the patient the longer survival. For this purpose, systems for acute extracellular recordings of single neuron and multi-unit activity are considered promising. Here we describe a system to be used with 16 microelectrodes arrays that consists of an autoclavable headstage, a built-in inserter for precise electrode positioning and a system that measures and controls...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

320-Channel Active Probe for High-Resolution Neuromonitoring and Responsive Neurostimulation
We present a 320-channel active probe for high-spatial-resolution neuromonitoring and responsive neurostimulation. The probe comprises an integrated circuit (IC) cell array bonded to the back side of a pitch-matched microelectrode array. The IC enables up to 256-site neural recording and 64-site neural stimulation at the spatial resolution of 400 $mu$ m and 200 $mu$ m, respectively. It is suitable for direct integration with electrode arrays with the shank pitch of integer multiples of 200 $mu$m. In the presented configuration, the IC is bonded with a 8$,times,$8 400 $mu$ m-pitch Utah electrode array (UEA) and up to additi...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

Active Electrode IC for EEG and Electrical Impedance Tomography With Continuous Monitoring of Contact Impedance
The IC presented integrates the front-end for EEG and Electrical Impedance Tomography (EIT) acquisition on the electrode, together with electrode-skin contact impedance monitoring and EIT current generation, so as to improve signal quality and integration of the two techniques for brain imaging applications. The electrode size is less than 2 ${rm cm}^{2}$ and only 4 wires connect the electrode to the back-end. The readout circuit is based on a Differential Difference Amplifier and performs single-ended amplification and frequency division multiplexing of the three signals that are sent to the back-end on a single wire whic...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

An Optically Powered CMOS Tracking System for 3 T Magnetic Resonance Environment
In this work, a fully optical Complementary Metal Oxide Semiconductor (CMOS) based catheter tracking system designed for 3 T Magnetic Resonance Imaging (MRI) environment is presented. The system aims to solve the Radio Frequency (RF) induced heating problem present in conventional wired catheter tracking systems used in MRI. It is based on an integrated circuit, consisting of a receiver and an optical power supply unit. The optical power supply unit includes a single on-chip photodiode and a DC-DC converter that boosts the low photodiode voltage output to voltages greater than 1.5 V. Through an optically driven switch, the...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

A 13.56-Mbps Pulse Delay Modulation Based Transceiver for Simultaneous Near-Field Data and Power Transmission
A fully-integrated near-field wireless transceiver has been presented for simultaneous data and power transmission across inductive links, which operates based on pulse delay modulation (PDM) technique. PDM is a low-power carrier-less modulation scheme that offers wide bandwidth along with robustness against strong power carrier interference, which makes it suitable for implantable neuroprosthetic devices, such as retinal implants. To transmit each bit, a pattern of narrow pulses are generated at the same frequency of the power carrier across the transmitter (Tx) data coil with specific time delays to initiate decaying rin...
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

IEEE Transactions on Biomedical Circuits and Systems publication information
(Source: IEEE Transactions on Biomedical Circuits and Systems)
Source: IEEE Transactions on Biomedical Circuits and Systems - January 27, 2015 Category: Biomedical Engineering Source Type: research

A Novel Paradigm for Engineering Education: Virtual Internships With Individualized Mentoring and Assessment of Engineering Thinking
Engineering virtual internships are a novel paradigm for providing authentic engineering experiences in the first-year curriculum. They are both individualized and accommodate large numbers of students. As we describe in this report, this approach can (a) enable students to solve complex engineering problems in a mentored, collaborative environment; (b) allow educators to assess engineering thinking; and (c) provide an introductory experience that students enjoy and find valuable. Furthermore, engineering virtual internships have been shown to increase students'—and especially women's—interest in and motivation to purs...
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

Measurement Systems for Cell Adhesive Forces
Cell adhesion to the extracellular matrix (ECM) involves integrin receptor–ligand binding and clustering to form focal adhesion (FA) complexes, which mechanically link the cell’s cytoskeleton to the ECM and regulate fundamental cell signaling pathways. Although elucidation of the biochemical events in cell-matrix adhesive interactions is rapidly advancing, recent studies show that the forces underlying cell-matrix adhesive interactions are also critical to cell responses. Therefore, multiple measurement systems have been developed to quantify the spatial and temporal dynamics of cell adhesive forces, and these systems ...
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

Deconstructing the Anterior Cruciate Ligament: What We Know and Do Not Know About Function, Material Properties, and Injury Mechanics
Anterior cruciate ligament (ACL) injury is a common and potentially catastrophic knee joint injury, afflicting a large number of males and particularly females annually. Apart from the obvious acute injury events, it also presents with significant long-term morbidities, in which osteoarthritis (OA) is a frequent and debilitative outcome. With these facts in mind, a vast amount of research has been undertaken over the past five decades geared toward characterizing the structural and mechanical behaviors of the native ACL tissue under various external load applications. While these efforts have afforded important insights, b...
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

The Effects of Mechanical Stimulation on Controlling and Maintaining Marrow Stromal Cell Differentiation Into Vascular Smooth Muscle Cells
In this study, initial experiments where a cyclic 10% strain was imposed on MSCs for 24 h at 0.1 Hz, 0.5 Hz, and 1 Hz determined that cells stretched at 1 Hz expressed significantly higher levels of VSMC-specific genetic and protein markers compared to samples stretched at 0.1 Hz. Conversely, samples stretched at 0.1 Hz expressed higher levels of osteoblast-specific genetic and protein markers compared to the samples stretched at 1 Hz. More importantly, sequential application of 24–48 h periods of 0.1 Hz and 1 Hz strain-induced genetic and protein marker expression levels similar to the VSMC profile s...
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

Is My Model Good Enough? Best Practices for Verification and Validation of Musculoskeletal Models and Simulations of Movement
We present a series of case studies to illustrate key principles. In closing, we discuss challenges the community must overcome to ensure that modeling and simulation are successfully used to solve the broad spectrum of problems that limit human mobility. (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

Biophysical Analysis of Dystrophic and Osteogenic Models of Valvular Calcification
Calcific aortic valve disease (CAVD) is a significant cardiovascular disorder characterized by the formation of calcific nodules (CN) on the valve. In vitro assays studying the formation of these nodules were developed and have led to many significant mechanistic findings; however, the biophysical properties of CNs have not been clearly defined. A thorough analysis of dystrophic and osteogenic nodules utilizing scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and atomic force microscopy (AFM) was conducted to describe calcific nodule properties and provide a link between calcific nodule morphogenes...
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

A Subject-Specific Musculoskeletal Modeling Framework to Predict In Vivo Mechanics of Total Knee Arthroplasty
We present a methodology to develop subject-specific models able to simultaneously predict muscle, ligament, and knee joint contact forces along with secondary knee kinematics. The MS architecture of a generic cadaver-based model was scaled using an advanced morphing technique to the subject-specific morphology of a patient implanted with an instrumented total knee arthroplasty (TKA) available in the fifth “grand challenge competition to predict in vivo knee loads” dataset. We implemented two separate knee models, one employing traditional hinge constraints, which was solved using an inverse dynamics technique, and ano...
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

Epigenetic Changes During Mechanically Induced Osteogenic Lineage Commitment
Osteogenic lineage commitment is often evaluated by analyzing gene expression. However, many genes are transiently expressed during differentiation. The availability of genes for expression is influenced by epigenetic state, which affects the heterochromatin structure. DNA methylation, a form of epigenetic regulation, is stable and heritable. Therefore, analyzing methylation status may be less temporally dependent and more informative for evaluating lineage commitment. Here we analyzed the effect of mechanical stimulation on osteogenic differentiation by applying fluid shear stress for 24 hr to osteocytes and then applying...
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

2014 World Congress of Biomechanics Student Paper Competition
(Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

Harnessing Biomechanics to Develop Cartilage Regeneration Strategies
This article provides a review of important steps toward regeneration of articular cartilage with suitable biomechanical properties. As a first step, biomechanical and biochemical characterization studies at the tissue level were used to provide design criteria for engineering neotissues. Extending this work to the single cell and subcellular levels has helped to develop biochemical and mechanical stimuli for tissue engineering studies. This strong mechanobiological foundation guided studies on regenerating hyaline articular cartilage, the knee meniscus, and temporomandibular joint (TMJ) fibrocartilage. Initial tissue engi...
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research

2014 Editors' Choice Papers
As part of the Annual Special Issue, the Journal of Biomechanical Engineering (JBME) Associate Editors selected the top papers published in the journal during 2014. Those Editors' Choice papers, listed below in chronological order, exemplified both the high quality and the breadth of papers published in the journal. Congratulations to these authors and to all authors whose work appeared in JBME over the past year! (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - January 24, 2015 Category: Biomedical Engineering Source Type: research