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International Journal for Numerical Methods in Biomedical Engineering

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https://www.readbyqxmd.com/read/28749579/a-new-type-of-neurons-for-machine-learning
#1
Fenglei Fan, Wenxiang Cong, Ge Wang
In machine learning, the use of an artificial neural network is the mainstream approach. Such a network consists of layers of neurons. These neurons are of the same type characterized by the two features: (1) an inner product of an input vector and a matching weighting vector of trainable parameters and (2) a nonlinear excitation function. Here we investigate the possibility of replacing the inner product with a quadratic function of the input vector, thereby upgrading the 1(st) order neuron to the 2(nd) order neuron, empowering individual neurons, and facilitating the optimization of neural networks...
July 27, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28744968/benchmark-problems-for-numerical-treatment-of-backflow-at-open-boundaries
#2
C Bertoglio, A Caiazzo, Y Bazilevs, M Braack, M Esmaily, V Gravemeier, A Marsden, O Pironneau, I E Vignon-Clementel, W A Wall
In computational fluid dynamics, incoming velocity at open boundaries, or backflow, often yields to unphysical instabilities already for moderate Reynolds numbers. Several treatments to overcome these backflow instabilities have been proposed in the literature. However, these approaches have not yet been compared in detail in terms of accuracy in different physiological regimes, in particular due to the difficulty to generate stable reference solutions apart from analytical forms. In this work, we present a set of benchmark problems in order to compare different methods in different backflow regimes (with a full reversal flow and with propagating vortices after a stenosis)...
July 25, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28744962/inverse-estimation-of-cardiac-activation-times-via-gradient-based-optimisation
#3
Siri Kallhovd, Mary M Maleckar, Marie E Rognes
Computational modeling may provide a quantitative framework for integrating multi-scale data to gain insight into mechanisms of heart disease, identify and test pharmacological and electrical therapy and interventions, and support clinical decisions. Patient-specific computational cardiac models can help guide such procedures, and cardiac inverse modelling is a promising alternative to adequately personalize these models. Indeed, full cardiac inverse modelling is currently becoming computationally feasible; however, fundamental work to assess the feasibility of emerging techniques is still needed...
July 25, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28677268/integration-of-element-specific-persistent-homology-and-machine-learning-for-protein-ligand-binding-affinity-prediction
#4
Zixuan Cang, Guo Wei Wei
Protein-ligand binding is a fundamental biological process that is paramount to many other biological processes, such as signal transduction, metabolic pathways, enzyme construction, cell secretion, gene expression, etc. Accurate prediction of protein-ligand binding affinities is vital to rational drug design and the understanding of protein-ligand binding and binding induced function. Existing binding affinity prediction methods are inundated with geometric detail and involve excessively high dimensions, which undermines their predictive power for massive binding data...
July 5, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28636811/performance-evaluation-of-gpu-parallelization-space-time-adaptive-algorithms-and-their-combination-for-simulating-cardiac-electrophysiology
#5
Rafael S Oliveira, Bernardo M Rocha, Denise Burgarelli, Wagner Meira, Christakis Constantinides, Rodrigo Weber Dos Santos
The use of computer models as a tool for the study and understanding of the complex phenomena of cardiac electrophysiology has attained increased importance nowadays. At the same time, the increased complexity of the biophysical processes translates into complex computational and mathematical models. In order to speed up cardiac simulations and to allow more precise and realistic uses, two different techniques have been traditionally exploited: parallel computing and sophisticated numerical methods. In this work, we combine a modern parallel computing technique based on multicore and graphics processing units (GPUs), and a sophisticated numerical method based on a new space-time adaptive algorithm...
June 21, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28621037/gingival-morphology-controlled-design-of-the-complete-denture-baseplate
#6
Ning Dai, Xiaoling Yu, Yuchun Sun
A removable complete denture is still the main selection for edentulous patients. Over the last five years, digital technologies for producing complete dentures have rapidly developed. Nevertheless, the design method for the baseplate has become the bottleneck of digital complete denture technology development. In this study, we report a novel method for the generation of aesthetic gingiva and polished surfaces of complete dentures that are driven by the feature curve, which can be conveniently modified using the gingival shape factor...
June 16, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28618187/physically-consistent-data-assimilation-method-based-on-feedback-control-for-patient-specific-blood-flow-analysis
#7
Satoshi Ii, Mohd Azrul Hisham Mohd Adib, Yoshiyuki Watanabe, Shigeo Wada
This paper presents a novel data assimilation method for patient-specific blood flow analysis based on feedback control theory called the physically consistent feedback control-based data assimilation (PFC-DA) method. In the PFC-DA method, the signal, which is the residual error term of the velocity when comparing the numerical and reference measurement data, is cast as a source term in a Poisson equation for the scalar potential field that induces flow in a closed system. The pressure values at the inlet and outlet boundaries are recursively calculated by this scalar potential field...
June 15, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28614900/computational-method-for-estimating-boundary-of-abdominal-subcutaneous-fat-for-absolute-electrical-impedance-tomography
#8
Tohru F Yamaguchi, Yoshiwo Okamoto
Abdominal fat accumulation is considered an essential indicator of human health. Electrical impedance tomography has considerable potential for abdominal fat imaging because of the low specific conductivity of human body fat. In this paper, we propose a robust reconstruction method for high-fidelity conductivity imaging by abstraction of the abdominal cross section using a relatively small number of parameters. Toward this end, we assume homogeneous conductivity in the abdominal subcutaneous fat area, and characterize its geometrical shape by parameters defined as the ratio of the distance from the center to boundary of subcutaneous fat to the distance from the center to outer boundary in 64 equiangular directions...
June 14, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28603939/mesh-free-based-variational-level-set-evolution-for-breast-region-segmentation-and-abnormality-detection-using-mammograms
#9
Kanchan L Kashyap, Manish K Bajpai, Pritee Khanna, George Giakos
Automatic segmentation of abnormal region is a crucial task in computer-aided detection system using mammograms. In this work, an automatic abnormality detection algorithm using mammographic images is proposed. In the preprocessing step, partial differential equation-based variational level set method is used for breast region extraction. The evolution of the level set method is done by applying mesh-free-based radial basis function (RBF). The limitation of mesh-based approach is removed by using mesh-free-based RBF method...
June 11, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28600860/estimating-the-accuracy-of-a-reduced-order-model-for-the-calculation-of-fractional-flow-reserve-ffr
#10
Etienne Boileau, Sanjay Pant, Carl Roobottom, Igor Sazonov, Jingjing Deng, Xianghua Xie, Perumal Nithiarasu
Image-based non-invasive fractional flow reserve (FFR) is an emergent approach to determine the functional relevance of coronary stenoses. The present work aimed to determine the feasibility of using a method based on coronary computed tomography angiography (CCTA) and reduced-order models (0D-1D) for the evaluation of coronary stenoses. The reduced-order methodology (cFFRro ) was kept as simple as possible and did not include pressure drop or stenosis models. The geometry definition was incorporated into the physical model used to solve coronary flow and pressure...
June 9, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28574647/robust-non-dimensional-estimators-to-assess-the-nasal-airflow-in-health-and-disease
#11
E Sanmiguel-Rojas, M A Burgos, C Del Pino, M A Sevilla-García, F Esteban-Ortega
There are significant variations of both human nose shapes and airflow patterns inside nasal cavities, so it is difficult to provide a comprehensive medical identification using a universal template for what otolaryngologists consider normal breathing at rest. In addition, airflow patterns present even more random characteristics in diseased nasal cavities. In order to give a medical assessment to differentiate the nasal cavities in health and disease, we propose two non-dimensional estimators obtained from both medical images and computational fluid dynamics (CFD)...
June 2, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28570783/on-the-importance-of-retaining-stresses-and-strains-in-repositioning-computational-biomechanical-models-of-the-cervical-spine
#12
Solomon Boakye-Yiadom, Duane S Cronin
Human body models are created in a specific posture and often repositioned and analyzed without retaining stresses that result from repositioning. For example, repositioning a human neck model within the physiological range of motion to a head-turned posture prior to an impact results in initial stresses within the tissues distracted from their neutral position. The aim of this study was to investigate the effect of repositioning on the subsequent kinetics, kinematics and failure modes of a lower cervical spine motion segment, to support future research at the full neck level...
June 1, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28558418/retraction-statement-mathematical-based-modeling-and-prediction-of-the-effect-of-external-stimuli-on-human-gait
#13
(no author information available yet)
Following acceptance within International Journal for Numerical Methods in Biomedical Engineering, and after publication as an Accepted Article on Wiley Online Library on 30 May 2017, a potential problem has been identified concerning "Retraction statement: Mathematical-based modeling and prediction of the effect of external stimuli on human gait" (doi: 10.1002/cnm.2902). We are suspending further publication pending investigation.
May 30, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28558162/a-numerical-investigation-and-experimental-verification-of-size-effects-in-loaded-bovine-cortical-bone
#14
J C Frame, M A Wheel, P E Riches
In this paper we present two and three dimensional finite element based numerical models of loaded bovine cortical bone that explicitly incorporate the dominant microstructural feature: the vascular channel or Haversian canal system. The finite element models along with the representation of the microstructure within them are relatively simple: two dimensional models, consisting of a structured mesh of linear elastic planar elements punctuated by a periodic distribution of circular voids, are used to represent beam samples of cortical bone in which the channels are orientated perpendicular to the sample major axis, while three dimensional models, employing a corresponding mesh of equivalent solid elements, represent those samples in which the canals are aligned with the axis...
May 30, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28557354/modeling-liver-electrical-conductivity-during-hypertonic-injection
#15
Quim Castellví, Patricia Sánchez-Velázquez, Xavier Moll, Enrique Berjano, Anna Andaluz, Fernando Burdío, Bart Bijnens, Antoni Ivorra
Metastases in the liver frequently grow as scattered tumor nodules which neither can be removed by surgical resection nor focally ablated. Previously, we have proposed a novel technique based on irreversible electroporation which may be able to simultaneously treat all nodules in the liver while sparing healthy tissue. The proposed technique requires increasing the electrical conductivity of healthy liver by injecting a hypersaline solution through the portal vein. Aiming to assess the capability of increasing the global conductivity of the liver by means of hypersaline fluids, here it is presented a mathematical model which estimates the NaCl distribution within the liver and the resulting conductivity change...
May 30, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28548240/viscoelastic-computational-modeling-of-the-human-head-neck-system-eigenfrequencies-and-time-dependent-analysis
#16
E Boccia, A Gizzi, C Cherubini, M G C Nestola, S Filippi
A subject-specific three-dimensional viscoelastic finite element model of the human head-neck system is presented and investigated based on Computed Tomography and Magnetic Resonance biomedical images. Ad hoc imaging processing tools are developed for the reconstruction of the simulation domain geometry and the internal distribution of bone and soft tissues. Materials viscoelastic properties are characterized point-wise through an image-based interpolating function used then for assigning the constitutive prescriptions of a heterogenous viscoelastic continuum model...
May 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28548237/simulation-of-non-linear-transient-elastography-finite-element-model-for-the-propagation-of-shear-waves-in-homogeneous-soft-tissues
#17
W Ye, A Bel-Brunon, S Catheline, A Combescure, M Rochette
In this study, visco-hyperelastic Landau's model which is widely used in acoustical physic field is introduced into a finite element formulation. It is designed to model the non-linear behaviour of finite amplitude shear waves in soft solids, typically, in biological tissues. This law is employed in finite element models based on elastography experiments reported in [1], the simulations results show a good agreement with the experimental studyred: it is observed in both that a plane shear wave generates only odd harmonics and a nonplane wave generates both odd and even harmonics in the spectral domain...
May 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28544269/a-novel-approach-for-early-evaluation-of-orthodontic-process-by-a-numerical-thermo-mechanical-analysis
#18
Z Heidary, A Mojra, M Shirazi, M Bazargan
The main objective of this paper is to propose a novel method that provides an opportunity to evaluate an orthodontic process at early phase of the treatment. This was accomplished by finding out a correlation between the applied orthodontic force and thermal variations in the tooth structure. To this end, geometry of the human tooth surrounded by the connective soft tissue called the periodontal ligament and the bone was constructed by employing dental CT scan images of a specific case. The periodontal ligament was modeled by finite strain viscoelastic model through a nonlinear stress-strain relation (hyperelasticity) and nonlinear stress-time relation (viscoelasticity)...
May 21, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28523829/the-prediction-of-viscous-losses-and-pressure-drop-in-models-of-the-human-airways
#19
A K Wells, I P Jones, S Hamill, R Bordas
This paper examines the viscous flow resistance in branching tubes as applied to simplified models of the lungs, and compares the results of Computational Fluid Dynamics (CFD) simulations for a range of conditions with measurement data. The results are in good agreement with the available measurement data for both inspiration and expiration. A detailed sensitivity analysis of the dissipation and viscous resistance in a branch then examines the ratio of the viscous resistance to that for a fully developed Poiseuille flow, Z...
May 18, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28521384/analysis-of-tenodesis-techiques-for-treatment-of-scapholunate-instability-using-the-finite-element-method
#20
Teresa Alonso Rasgado, Qinghang Zhang, David Jimenez Cruz, Colin Bailey, Elizabeth Pinder, Avanthi Mandaleson, Sumedh Talwalkar
Chronic Scapholunate ligament (SL) injuries are difficult to treat and can lead to wrist dysfunction. Whilst several tendon reconstruction techniques have been employed in the management of SL instability, SL gap reappearance after surgery has been reported. Using finite element model and cadaveric study data we investigated the performance of the Corella, schapolunate axis (SLAM) and modified Brunelli tenodesis (MBT) techniques. Virtual tenodesis surgery was undertaken in 3D finite element (FE) models to obtain the scapholunate (SL) gap and angle resulting from the three reconstruction techniques...
May 18, 2017: International Journal for Numerical Methods in Biomedical Engineering
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