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

Criticité des dispositifs médicaux : méthodes et taux normé
Publication date: Available online 28 February 2015 Source:IRBM News Author(s): G. Farges (Source: IRBM News)
Source: IRBM News - February 28, 2015 Category: Biomedical Engineering Source Type: research

Robotic-Assisted Gait Training in Neurological Patients: Who May Benefit?
Abstract Regaining one's ability to walk is of great importance for neurological patients and is a major goal of all rehabilitation programs. Gait training of severely affected patients after the neurological event is technically difficult because of their motor weakness and balance disturbances. An innovative locomotor training that incorporates high repetitions of task-oriented practice by the use of body weight-supported treadmill training (BWSTT) was developed to overcome these obstacles. To facilitate the delivery of BWSTT, a motorized robotic driven gait orthosis (robotic-assisted gait training-RAGT) was deve...
Source: Annals of Biomedical Engineering - February 28, 2015 Category: Biomedical Engineering Authors: Schwartz I, Meiner Z Tags: Ann Biomed Eng Source Type: research

An Efficient Compartmental Model for Real-Time Node Tracking Over Cognitive Wireless Sensor Networks
In this paper, an efficient compartmental model for real-time node tracking over cognitive wireless sensor networks is proposed. The compartmental model is developed in a multi-sensor fusion framework with cognitive bandwidth utilization. The multi-sensor data attenuation model using radio, acoustic, and visible light signal is first derived using a sum of exponentials model. A compartmental model that selectively combines the multi-sensor data is then developed. The selection of individual sensor data is based on the criterion of bandwidth utilization. The parameters of the compartmental model are computed using the modif...
Source: IEEE Transactions on Signal Processing - February 27, 2015 Category: Biomedical Engineering Source Type: research

A Cognitive Algorithm for Received Signal Strength Based Localization
In this paper, we propose a method to localize a wireless and stationary blind node based on received signal strength measurements; the positioning scheme relies on the statistical path loss model. The operating environment is either non-homogeneous, i.e., the attenuation factors of the various links are different, or homogeneous, i.e., all links share one and the same attenuation factor. We introduce a cognitive procedure to circumvent the a priori uncertainty on the actual scenario being in force: the first stage is a properly designed hypothesis test, fed by measurements between anchors, moving along known trajectories,...
Source: IEEE Transactions on Signal Processing - February 27, 2015 Category: Biomedical Engineering Source Type: research

Harvest-Then-Cooperate: Wireless-Powered Cooperative Communications
In this paper, we consider a wireless-powered cooperative communication network consisting of one hybrid access-point (AP), one source, and one relay. In contrast to conventional cooperative networks, the source and relay in the considered network have no embedded energy supply. They need to rely on the energy harvested from the signals broadcasted by the AP for their cooperative information transmission. Based on this three-node reference model, we propose a harvest-then-cooperate (HTC) protocol, in which the source and relay harvest energy from the AP in the downlink and work cooperatively in the uplink for the source's ...
Source: IEEE Transactions on Signal Processing - February 27, 2015 Category: Biomedical Engineering Source Type: research

Cramér-Rao Bounds for SNR Estimation of Oversampled Linearly Modulated Signals
Most signal-to-noise ratio (SNR) estimators use the receiver matched filter output sampled at the symbol rate, an approach which does not preserve all information in the analog waveform due to aliasing. Thus, it is relevant to ask whether avoiding aliasing could improve SNR estimation. To this end, we compute the corresponding data-aided (DA) and nondata-aided (NDA) Cramér-Rao bounds (CRBs). We adopt a novel dual filter framework, which is shown to be information-preserving under suitable conditions and considerably simplifies the analysis. It is shown that the CRB can be substantially reduced by exploiting any avai...
Source: IEEE Transactions on Signal Processing - February 27, 2015 Category: Biomedical Engineering Source Type: research

Energy-Efficient Bandwidth and Power Allocation for Multi-Homing Networks
This paper investigates resource allocation for multi-homing networks where users can simultaneously transmit data to multiple radio access networks (RANs) using multiple air interfaces. We aim at optimally assigning the bandwidth and power to each user-RAN connection so as to maximize energy-efficiency of the entire network subject to user specific QoS requirements as well as the available resource budgets. First, we study the problem of resource allocation for scenarios where the connections between the users and the RANs are predefined, which naturally leads to a fractional program. To obtain the optimal solution effici...
Source: IEEE Transactions on Signal Processing - February 27, 2015 Category: Biomedical Engineering Source Type: research

PROSBOT – Model and image controlled prostatic robot
The objective of the simulator is to improve the learning curve of systematic and targeted prostate biopsy acquisition through realistic simulations of the gesture and a multitude of pedagogic modules. This paper reports the developed versions of the simulator and their evaluation. The robotic assistance system, called Apollo, is a co-manipulated robotic probe holder that aims at improving the clinical gesture through several functions, amongst which are: a) locking the probe in a target position, b) providing haptic feed-back to reduce gland deformation and c) gravity compensation. Two cadaver studies have shown that the ...
Source: IRBM - February 27, 2015 Category: Biomedical Engineering Source Type: research

Ultrasound imaging using CMUT – Techniques developed in the frame of the ANR BBMUT project
Publication date: Available online 26 February 2015 Source:IRBM Author(s): O. Basset , A. Bouakaz , N. Sénégond , M. Toulemonde , R. Guillermin , D. Fouan , F. Lin , F. Tourniaire , A. Cristea , A. Novell , E. Franceschini The early diagnosis of liver diseases and/or the identification of any focal lesions are the key issues in considering a favorable prognosis. These objectives require non-invasive dedicated diagnostic tools and justify the development of innovative techniques. The BBMUT project aims to exploit the properties of a new technology of ultrasound probes, called CMUT to propose new techniques for imaging a...
Source: IRBM - February 27, 2015 Category: Biomedical Engineering Source Type: research

Statistical atlas-based morphological variation analysis of the asian humerus: Towards consistent allometric implant positioning
Conclusion Morphologic analysis based on statistical atlases is novel and useful to characterize the Asian humerus. The humerus demonstrates gender-specific morphology. This unique approach provides information that is useful to the clinician and biomedical engineer, not only in the modification of current or design of future humeral implants, but also in the precise dynamic positioning of Asian-specific humeral implants to Asian patients. Our findings support the need for further development of humeral implants, curvilinear robotics, and the questioning of whether gender-specific devices are necessary. (Source:...
Source: International Journal of Computer Assisted Radiology and Surgery - February 26, 2015 Category: Intensive Care Source Type: research

Can Science and Technology Fix a Broken Heart?
Heart disease is the No. 1 cause of death in the United States, accounting for one in four deaths. While much has been learned about the risk factors for and the pathophysiology of heart disease and major advancements have been made in the pharmacologic and surgical treatment of this condition, we remain technologically naive in our ability to fix these "broken hearts." As we wrap up National Heart Month, I thought it would be valuable to explore this question of can science and technology fix a broken heart? To help answer this question, I had a conversation with Dr. Adam Feinberg, professor and biomedical researcher at ...
Source: Healthy Living - The Huffington Post - February 26, 2015 Category: Consumer Health Advice Source Type: news

The Direct Incorporation of Perfusion Defect Information to Define Ischemia and Infarction in a Finite Element Model of the Left Ventricle
This paper describes the process in which complex lesion geometries (specified by computer generated perfusion defects) are incorporated in the description of nonlinear finite element (FE) mechanical models used for specifying the motion of the left ventricle (LV) in the 4D extended cardiac torso (XCAT) phantom to simulate gated cardiac image data. An image interrogation process was developed to define the elements in the LV mesh as ischemic or infarcted based upon the values of sampled intensity levels of the perfusion maps. The intensity values were determined for each of the interior integration points of every element ...
Source: Journal of Biomechanical Engineering - February 26, 2015 Category: Biomedical Engineering Source Type: research

Unified frame of reference improves inter-subject variability of seismocardiograms
Conclusions: The results indicate that using a unified frame of reference is a promising method for improving the inter-subject variability of three-dimensional seismocardiograms. Also, it is observed that three-dimensional seismocardiograms seem to have latent inter-subject similarities, which are feasible to be revealed. Because the projections of the cardiac vibrations on the measurement axes differ significantly, it seems obligatory to use three-dimensional measurements when seismocardiogram analysis is based on waveform morphology. (Source: BioMedical Engineering OnLine)
Source: BioMedical Engineering OnLine - February 26, 2015 Category: Biomedical Engineering Authors: Mikko PaukkunenPetteri ParkkilaRaimo KettunenRaimo Sepponen Source Type: research

Characterization of Amphora sp., a newly isolated diatom wild strain, potentially usable for biodiesel production.
Abstract Microalgae as feedstock for biofuel production have attracted serious consideration as an important sustainable source of energy. For biodiesel production with microalgae, a series of consecutive processes should be performed as selection of adequate microalgal strains, mass culture, cell harvesting, oil extraction and transesterification. The aim of this study was to investigate the growth and lipid accumulation of a new isolated marine microalgal strain by optimizing culture medium composition and applying different stressful culture conditions. Microalga CTM 20023 was isolated from the evaporating salt-...
Source: Bioprocess and Biosystems Engineering - February 26, 2015 Category: Biomedical Engineering Authors: Chtourou H, Dahmen I, Jebali A, Karray F, Hassairi I, Abdelkafi S, Ayadi H, Sayadi S, Dhouib A Tags: Bioprocess Biosyst Eng Source Type: research

Influence of wheel configuration on wheelchair basketball performance: Wheel stiffness, tyre type and tyre orientation
The aim of the current investigation was to explore the lateral stiffness of different sports wheelchair wheels available to athletes in ‘new’ and ‘used’ conditions and to determine the effect of (a) stiffness, (b) tyre type (clincher vs. tubular) and (c) tyre orientation on the physiological and biomechanical responses to submaximal and maximal effort propulsion specific to wheelchair basketball. Eight able-bodied individuals participated in the laboratory-based testing, which took place on a wheelchair ergometer at two fixed speeds (1.1 and 2.2 m s−1). (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - February 25, 2015 Category: Biomedical Engineering Authors: B.S. Mason, M. Lemstra, L.H.V. van der Woude, R. Vegter, V.L. Goosey-Tolfrey Source Type: research

Effect of ion concentration on mechanosynthesis of carbonated chlorapatite nanopowders
Publication date: 1 May 2015 Source:Materials Letters, Volume 146 Author(s): Abbas Fahami , Bahman Nasiri-Tabrizi , Gary W. Beall , Belinda Pingguan-Murphy Carbonated chlorapatite nanopowders (n-CCAp) with different degrees of substitution were successfully synthesized by the one-step mechanochemical process. Results demonstrated that the formation of n-CCAp was influenced strongly by the carbonate content (x). From X-ray analysis, crystallite size, crystallinity degree, and unit cell volume of n-CCAp decreased significantly as carbonate content (x) increased from 0 to 2. Conversely, the lattice strain and the volume fra...
Source: Materials Letters - February 25, 2015 Category: Materials Science Source Type: research

Heterologous expression, purification, and phylogenetic analysis of oil-degrading biosurfactant biosynthesis genes from the marine sponge-associated Bacillus licheniformis NIOT-06.
In this study, the biosurfactant biosynthesis genes; 4'-pantetheinyl transferase (sfp), phosphopantetheinyl transferase (sfpO), and surfactin synthetase (srfA) have been characterized from the marine sponge-associated Bacillus licheniformis NIOT-06 from the Andaman and Nicobar Islands. The purified recombinant biosurfactant revealed excellent emulsification activity with crude oil and kerosene. Reverse-phase high-performance liquid chromatography resolved the purified recombinant biosurfactant into several fractions and one of which had significant surface tension reducing property. Fourier transform infrared spectroscopy ...
Source: Bioprocess and Biosystems Engineering - February 25, 2015 Category: Biomedical Engineering Authors: Anburajan L, Meena B, Raghavan RV, Shridhar D, Joseph TC, Vinithkumar NV, Dharani G, Dheenan PS, Kirubagaran R Tags: Bioprocess Biosyst Eng Source Type: research

VEGF-Loaded Nanoparticle-Modified BAMAs Enhance Angiogenesis and Inhibit Graft Shrinkage in Tissue-Engineered Bladder.
In this study, we investigated the use of bladder acellular matrix allografts (BAMAs) modified with vascular endothelial growth factor (VEGF)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) for the long-term sustained release of VEGF to enhance blood supply and inhibit graft shrinkage in a rabbit model of bladder reconstruction. Rabbits underwent partial bladder cystectomy using a 2 × 3 cm BAMA modified with VEGF-loaded PLGA NPs in the experimental group, while no modification was used in the control. Histology and immunohistochemical analyses showed that urothelium, smooth muscle fibers and blood vesse...
Source: Annals of Biomedical Engineering - February 25, 2015 Category: Biomedical Engineering Authors: Jiang X, Xiong Q, Xu G, Lin H, Fang X, Cui D, Xu M, Chen F, Geng H Tags: Ann Biomed Eng Source Type: research

Tissue Engineered Constructs: Perspectives on Clinical Translation.
Abstract In this article, a "bedside to bench and back" approach for developing tissue engineered medical products (TEMPs) for clinical applications is reviewed. The driving force behind this approach is unmet clinical needs. Preclinical research, both in vitro and in vivo using small and large animal models, will help find solutions to key research questions. In clinical research, ethical issues regarding the use of cells and tissues, their sources, donor consent, as well as clinical trials are important considerations. Regulatory issues, at both institutional and government levels, must be addressed prior to the ...
Source: Annals of Biomedical Engineering - February 25, 2015 Category: Biomedical Engineering Authors: Lu L, Arbit HM, Herrick JL, Segovis SG, Maran A, Yaszemski MJ Tags: Ann Biomed Eng Source Type: research

A Mathematical Model for Understanding Fluid Flow Through Engineered Tissues Containing Microvessels
Knowledge is limited about fluid flow in tissues containing engineered microvessels, which can be substantially different in topology than native capillary networks. A need exists for a computational model that allows for flow through tissues dense in nonpercolating and possibly nonperfusable microvessels to be efficiently evaluated. A finite difference (FD) model based on Poiseuille flow through a distribution of straight tubes acting as point sources and sinks, and Darcy flow through the interstitium, was developed to describe fluid flow through a tissue containing engineered microvessels. Accuracy of the FD model was as...
Source: Journal of Biomechanical Engineering - February 24, 2015 Category: Biomedical Engineering Source Type: research

Model Order Selection for Complex Sinusoids in the Presence of Unknown Correlated Gaussian Noise
We consider the problem of detecting and estimating the amplitudes and frequencies of an unknown number of complex sinusoids based on noisy observations from an unstructured array. In parametric detection problems like this, information theoretic criteria such as minimum description length (MDL) and Akaike information criterion (AIC) have previously been used for joint detection and estimation. In our paper, model selection based on extreme value theory (EVT), which has previously been used for enumerating real sinusoidal components from one-dimensional observations, is generalized to the case of multidimensional complex o...
Source: IEEE Transactions on Signal Processing - February 24, 2015 Category: Biomedical Engineering Source Type: research

Robust Adaptive Beamforming With a Novel Interference-Plus-Noise Covariance Matrix Reconstruction Method
Recently, a new robust adaptive beamforming (RAB) technique was proposed to remove the signal of interest (SOI) component from the sample covariance matrix based on interference-plus-noise covariance matrix reconstruction, which utilizes the Capon spectrum estimator integrated over a region separated from the direction of the SOI. However, the extreme condition of the reconstruction-based technique, that the precise information about the array structure is known in advance, is almost impossible in practice. In this paper, a novel method to reconstruct the interference-plus-noise covariance matrix is proposed. Considering t...
Source: IEEE Transactions on Signal Processing - February 24, 2015 Category: Biomedical Engineering Source Type: research

Multiperiod Scheduling for Wireless Sensor Networks: A Distributed Consensus Approach
In wireless sensor networks, many sensors face energy constraints and can switch among different work modes to save energy. How to properly schedule work modes is important for network utility maximization (NUM) in the long run. This paper proposes multiperiod scheduling to maximize total network utility by considering energy constraints and periodic sensing requirements. This NUM problem presents challenging mixed-integer programming, and it is difficult to solve by using a centralized approach under complete information. Thus, we first simplify the multiperiod problem to an equivalent single-period problem, and then furt...
Source: IEEE Transactions on Signal Processing - February 24, 2015 Category: Biomedical Engineering Source Type: research

Sparse Generalized Eigenvalue Problem Via Smooth Optimization
In this paper, we consider an $ell_{0}$-norm penalized formulation of the generalized eigenvalue problem (GEP), aimed at extracting the leading sparse generalized eigenvector of a matrix pair. The formulation involves maximization of a discontinuous nonconcave objective function over a nonconvex constraint set, and is therefore computationally intractable. To tackle the problem, we first approximate the $ell_{0}$-norm by a continuous surrogate function. Then an algorithm is developed via iteratively majorizing the surrogate function by a quadratic separable function, which at each iteration reduces to a regular generalized...
Source: IEEE Transactions on Signal Processing - February 24, 2015 Category: Biomedical Engineering Source Type: research

Estimation of Inlet Flow Rates for Image-Based Aneurysm CFD Models: Where and How to Begin?
Abstract Patient-specific flow rates are rarely available for image-based computational fluid dynamics models. Instead, flow rates are often assumed to scale according to the diameters of the arteries of interest. Our goal was to determine how choice of inlet location and scaling law affect such model-based estimation of inflow rates. We focused on 37 internal carotid artery (ICA) aneurysm cases from the Aneurisk cohort. An average ICA flow rate of 245 mL min(-1) was assumed from the literature, and then rescaled for each case according to its inlet diameter squared (assuming a fixed velocity) or cubed (assuming ...
Source: Annals of Biomedical Engineering - February 24, 2015 Category: Biomedical Engineering Authors: Valen-Sendstad K, Piccinelli M, KrishnankuttyRema R, Steinman DA Tags: Ann Biomed Eng Source Type: research

Quantification of Shear Deformations and Corresponding Stresses in the Biaxially Tested Human Myocardium.
Abstract One goal of cardiac research is to perform numerical simulations to describe/reproduce the mechanoelectrical function of the human myocardium in health and disease. Such simulations are based on a complex combination of mathematical models describing the passive mechanical behavior of the myocardium and its electrophysiology, i.e., the activation of cardiac muscle cells. The problem in developing adequate constitutive models is the shortage of experimental data suitable for detailed parameter estimation in specific functional forms. A combination of shear and biaxial extension tests with different loading ...
Source: Annals of Biomedical Engineering - February 24, 2015 Category: Biomedical Engineering Authors: Sommer G, Haspinger DC, Andrä M, Sacherer M, Viertler C, Regitnig P, Holzapfel GA Tags: Ann Biomed Eng Source Type: research

Semantic interoperability platform for Healthcare Information Exchange
Conclusion: The TeRSan platform is an innovative semantic interoperability framework that (1) provides standard-based semantic services applicable to any HIE infrastructure and (2) preserves the use of local terminologies and local models by end users (health professionals' priority). (Source: IRBM)
Source: IRBM - February 22, 2015 Category: Biomedical Engineering Source Type: research

Effect of Potting Technique on the Measurement of Six Degree-of-Freedom Viscoelastic Properties of Human Lumbar Spine Segments
Polymethyl methacrylate (PMMA) and Wood's Metal are fixation media for biomechanical testing; however, the effect of each potting medium on the measured six degree-of-freedom (DOF) mechanical properties of human lumbar intervertebral discs is unknown. The first aim of this study was to compare the measured 6DOF elastic and viscoelastic properties of the disc when embedded in PMMA compared to repotting in Wood's Metal. The second aim was to compare the surface temperature of the disc when potted with PMMA and Wood's Metal. Six human lumbar functional spinal units (FSUs) were first potted in PMMA, and subjected to overnight ...
Source: Journal of Biomechanical Engineering - February 21, 2015 Category: Biomedical Engineering Source Type: research

Characterization of the Discrepancies Between Four-Dimensional Phase-Contrast Magnetic Resonance Imaging and In-Silico Simulations of Cerebrospinal Fluid Dynamics
The purpose of the present study was to compare subject-specific magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) simulations with time-resolved three-directional (3D) velocity-encoded phase-contrast MRI (4D PCMRI) measurements of the cerebrospinal fluid (CSF) velocity field in the cervical spinal subarachnoid space (SSS). Three-dimensional models of the cervical SSS were constructed based on MRI image segmentation and anatomical measurements for a healthy subject and patient with Chiari I malformation. CFD was used to simulate the CSF motion and compared to the 4D PCMRI measurements. Four-dimensio...
Source: Journal of Biomechanical Engineering - February 21, 2015 Category: Biomedical Engineering Source Type: research

Contribution of Collagen Fiber Undulation to Regional Biomechanical Properties Along Porcine Thoracic Aorta
This study is focused on the role of layer-specific collagen undulation in the variation of mechanical properties along the porcine descending thoracic aorta. Planar biaxial tensile tests are performed to characterize the hyperelastic anisotropic mechanical behavior of tissues dissected from four locations along the thoracic aorta. Multiphoton microscopy is used to image the associated regional microstructure. Exponential-based and recruitment-based constitutive models are used to account for the observed mechanical behavior while considering the aortic wall as a composite of two layers with independent properties. An elev...
Source: Journal of Biomechanical Engineering - February 21, 2015 Category: Biomedical Engineering Source Type: research

A retrospective analysis of oxygen concentrator maintenance needs and costs in a low-resource setting: experience from The Gambia
Abstract Oxygen is an essential medicine for the treatment of pneumonia, the leading cause of death in children under five worldwide. Yet, providing a sufficient and reliable supply of oxygen is a major challenge for many health facilities in the developing world, particularly in paediatric care units. The cost-effectiveness of oxygen concentrators versus compressed gas cylinders as a source of oxygen in low-resource health facilities has been demonstrated, but evidence of their long-term functionality is scarce. The Biomedical Engineering Department at the Medical Research Council Unit in The Gambia manages and m...
Source: Health and Technology - February 21, 2015 Category: Information Technology Source Type: research

3-D trajectory of body sway angles: A technique for quantifying postural stability
In this study, ten patients with progressive cerebellar ataxia and eleven healthy subjects were measured and a statistical analysis was performed. The results yielded by new method show that the total trajectory lengths of patients with cerebellar disease are significantly larger than the total trajectory lengths of healthy subjects. It is evident from the median of the total trajectory lengths that the method based on the data obtained by an inexpensive orientation tracker may be used to quantify human postural stability and enables for studying body sway in 3-D space. For example, the 3-D deviations of the trunk angles i...
Source: Biocybernetics and Biomedical Engineering - February 21, 2015 Category: Biomedical Engineering Source Type: research

Iterative multi-channel radio frequency pulse calibration with improving B 1 field uniformity in high field MRI
Conclusions: Since the proposed RF pulse calibration is not based on B 1 mapping, the RF pulse calibration time could be much shorter than the B 1-mapping based methods. The proposed method is expected to be a practical substitute for the B 1-mapping-based B 1 shimming methods when long pre-scan time is not tolerable. (Source: BioMedical Engineering OnLine)
Source: BioMedical Engineering OnLine - February 21, 2015 Category: Biomedical Engineering Authors: Daniel HernandezMin ChoSoo Lee Source Type: research

Differential sequential patterns supporting insulin therapy of new-onset type 1 diabetes
Conclusions: The usefulness of the proposed approach was evident in the results of experiments in which juvenile diabetic patients actual data were used. It was confirmed that the proposed DSPs can be used to guide the therapy of numerous juvenile patients with type 1 diabetes. (Source: BioMedical Engineering OnLine)
Source: BioMedical Engineering OnLine - February 21, 2015 Category: Biomedical Engineering Authors: Rafa¿ DejaWojciech FroelichGra¿yna Deja Source Type: research

Large-scale crystallization of proteins for purification and formulation.
Abstract Since about 170 years, salts were used to create supersaturated solutions and crystallize proteins. The dehydrating effect of salts as well as their kosmotropic or chaotropic character was revealed. Even the suitability of organic solvents for crystallization was already recognized. Interestingly, what was performed during the early times is still practiced today. A lot of effort was put into understanding the underlying physico-chemical interaction mechanisms leading to protein crystallization. However, it was understood that already the solvation of proteins is a highly complex process not to mention th...
Source: Bioprocess and Biosystems Engineering - February 21, 2015 Category: Biomedical Engineering Authors: Hekmat D Tags: Bioprocess Biosyst Eng Source Type: research

Microfabricated infuse-withdraw micropump component for an integrated inner-ear drug-delivery platform.
Abstract One of the major challenges in treatment of auditory disorders is that many therapeutic compounds are toxic when delivered systemically. Local intracochlear delivery methods are becoming critical in emerging treatments and in drug discovery. Direct infusion via cochleostomy, in particular, is attractive from a pharmacokinetics standpoint, as there is potential for the kinetics of delivery to be well-controlled. Direct infusion is compatible with a large number of drug types, including large, complex molecules such as proteins and unstable molecules such as siRNA. In addition, hair-cell regeneration therapy...
Source: Biomedical Microdevices - February 20, 2015 Category: Biomedical Engineering Authors: Tandon V, Kang WS, Spencer AJ, Kim ES, Pararas EE, McKenna MJ, Kujawa SG, Mescher MJ, Fiering J, Sewell WF, Borenstein JT Tags: Biomed Microdevices Source Type: research

3D printing of soft lithography mold for rapid production of polydimethylsiloxane-based microfluidic devices for cell stimulation with concentration gradients.
Abstract Three-dimensional (3D) printing is advantageous over conventional technologies for the fabrication of sophisticated structures such as 3D micro-channels for future applications in tissue engineering and drug screening. We aimed to apply this technology to cell-based assays using polydimethylsiloxane (PDMS), the most commonly used material for fabrication of micro-channels used for cell culture experiments. Useful properties of PDMS include biocompatibility, gas permeability and transparency. We developed a simple and robust protocol to generate PDMS-based devices using a soft lithography mold produced by 3...
Source: Biomedical Microdevices - February 20, 2015 Category: Biomedical Engineering Authors: Kamei K, Mashimo Y, Koyama Y, Fockenberg C, Nakashima M, Nakajima M, Li J, Chen Y Tags: Biomed Microdevices Source Type: research

Alternating Optimization of Sensing Matrix and Sparsifying Dictionary for Compressed Sensing
This paper deals with alternating optimization of sensing matrix and sparsifying dictionary for compressed sensing systems. Under the same framework proposed by J. M. Duarte-Carvajalino and G. Sapiro, a novel algorithm for optimal sparsifying dictionary design is derived with an optimized sensing matrix embedded. A closed-form solution to the optimal dictionary design problem is obtained. A new measure is proposed for optimizing sensing matrix and an algorithm is developed for solving the corresponding optimization problem. Experiments are carried out with synthetic data and real images, which demonstrate promising perform...
Source: IEEE Transactions on Signal Processing - February 20, 2015 Category: Biomedical Engineering Source Type: research

Gaussian Mixture Models Reduction by Variational Maximum Mutual Information
Gaussian mixture models (GMMs) are widely used in a variety of classification tasks where it is often important to approximate high order models by models with fewer components. The paper proposes a novel approach to this problem based on a parametric realization of the maximum mutual information (MMI) criterion and its approximation by a closed-form expression named variational-MMI (VMMI). The maximization of the VMMI can be carried out in an analytically tractable manner and it aims at improving the discrimination ability of the reduced set of models, a goal that was not targeted in previous approaches that simplify each...
Source: IEEE Transactions on Signal Processing - February 20, 2015 Category: Biomedical Engineering Source Type: research

3D Pseudolinear Target Motion Analysis From Angle Measurements
The paper presents a new pseudolinear estimator for 3D target motion analysis by a single moving ownship collecting azimuth and elevation angle measurements. The 3D pseudolinear estimator is derived as a small-noise approximation to the maximum-likelihood estimator and consists of a 2D pseudolinear estimator for the $xy$-components of the target motion parameters and a least-squares estimator for the $z$-component. To improve the poor bias performance of the 3D pseudolinear estimator, alternative estimators are proposed employing bias compensation and weighted instrumental variables. A selective-angle-measurement implement...
Source: IEEE Transactions on Signal Processing - February 20, 2015 Category: Biomedical Engineering Source Type: research

The Theory of Quaternion Matrix Derivatives
A systematic framework for the calculation of the derivatives of quaternion matrix functions with respect to quaternion matrix variables is introduced. The proposed approach is equipped with the matrix product and chain rules and applies to both analytic and nonanalytic functions of quaternion variables. This rectifies a mathematical shortcut in the existing methods, which incorrectly use the traditional product rule. We also show that within the proposed framework, the derivatives of quaternion matrix functions can be calculated directly, without using quaternion differentials or resorting to the isomorphism with real vec...
Source: IEEE Transactions on Signal Processing - February 20, 2015 Category: Biomedical Engineering Source Type: research