Determining the unknown material parameters of intact ventricular myocardium can be challenging due to highly nonlinear material behavior. Previous studies combining a gradient-search optimization procedure with finite element analysis (FEA) were limited to two-dimensional (2D) models or simplified three-dimensional (3D) geometries. Here we present a novel scheme to estimate unknown material parameters for ventricular myocardium by combining a genetic algorithm (GA) with nonlinear finite element analysis. This approach systematically explores the domain of the material parameters. The objective function to minimize was the error between simulated strain data and finite element model strains. The proposed scheme was validated for a 2D problem using a realistic material law for ventricular myocardium. Optimized material parameters were generally within 0.5% of the true values. To demonstrate the robustness of the new scheme, unknown material parameters were also determined for a realistic 3D heart model with an exponential hyperelastic material law. When using strains from two material points, the algorithm converged to parameters within 5% of the true values. We conclude that the proposed scheme is robust when estimating myocardial material parameters in 2D and 3D models.
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http://dx.doi.org/10.1016/j.jbiomech.2006.07.018 | DOI Listing |
J Clin Endocrinol Metab
January 2025
Department of Internal Medicine and Therapeutics, University of Pavia, 27100 Pavia, Italy.
Background: Thyroid nodules classified cytologically as low-risk indeterminate lesions (TIR3A) on fine-needle aspiration biopsy (FNAB) present a clinical challenge due to their uncertain malignancy risk. This single-center study aimed to evaluate the natural history of TIR3A nodules.
Materials And Methods: FNABs performed between July 2017 and December 2019 were retrospectively retrieved and patients with TIR3A nodules were evaluated at baseline and throughout a follow-up based on ultrasound (US) parameters and clinical data.
JMIR Res Protoc
January 2025
Department of Dermatology, Hospital Universitario Ramon y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain, Madrid, Spain.
Background: Psoriasis is an inflammatory disease primarily treated through molecular-targeted therapies. However, emerging evidence suggests that dietary interventions may also play a role in managing inflammation associated with this condition. The Mediterranean diet (MedDiet), prevalent in southern European countries, has been widely recognized for its ability to reduce cardiovascular mortality, largely due to its anti-inflammatory properties.
View Article and Find Full Text PDFJ Speech Lang Hear Res
January 2025
Division of Phoniatrics and Pediatric Audiology, Department of Otolaryngology, Munich University Hospital and Faculty of Medicine, Munich University (Ludwig-Maximilians-Universität), Germany.
Purpose: This study explores the effects of water intake and a hyaluronic acid (HA)-containing lozenge on acoustic measurements and vocal oscillation patterns investigated after a vocal loading test (VLT).
Method: Ten healthy subjects (five females, five males) read out loud a standardized text for 10 min at a target level of 80 dB(A), measured 30 cm from the mouth, under three conditions but each after fasting for 2 hr: (a) drinking 0.7 l of water, (b) sucking an HA-containing lozenge, and (c) neither of both before the VLT.
Phys Rev Lett
December 2024
University of Michigan, Department of Physics, Ann Arbor, Michigan 48109, USA.
Anisotropy is a fundamental property of both material and photonic systems. The interplay between material and photonic anisotropies, however, has hardly been explored due to the vastly different length scales. Here we demonstrate exciton polaritons in a 2D antiferromagnet, CrSBr, coupled with an anisotropic photonic crystal cavity, where the spin, atomic, and photonic anisotropies are strongly correlated.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
National University of Singapore, Department of Materials Science and Engineering, 9 Engineering Drive 1, Singapore 117575.
By virtue of being atomically thin, the electronic properties of heterostructures built from two-dimensional materials are strongly influenced by atomic relaxation. The atomic layers behave as flexible membranes rather than rigid crystals. Here we develop an analytical theory of lattice relaxation in twisted moiré materials.
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