scholarly journals Coronary arterial dynamics computation with medical-image-based time-dependent anatomical models and element-based zero-stress state estimates

2014 ◽  
Vol 54 (4) ◽  
pp. 1047-1053 ◽  
Author(s):  
Kenji Takizawa ◽  
Ryo Torii ◽  
Hirokazu Takagi ◽  
Tayfun E. Tezduyar ◽  
Xiao Y. Xu
Keyword(s):  
Stress State ◽  
Medical Image ◽  
Time Dependent ◽  
Anatomical Models ◽  
Coronary Arterial Dynamics

On the Connection Between Geometry and Statically Determined Membrane Stresses in the Human Cornea

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
M. Angelillo ◽  
A. Montanino ◽  
A. Pandolfi
Keyword(s):  
Intraocular Pressure ◽  
Stress State ◽  
Principal Stress ◽  
Collagen Fibrils ◽  
Equilibrium Analysis ◽  
Time Dependent ◽  
Patient Specific ◽  
Shear Stresses ◽  
Human Cornea ◽  
The Matrix

Abstract Under the action of the intraocular pressure (IOP), the human cornea is stressed and deforms acquiring a quasi-spherical configuration. If the stressed configuration is known, and the cornea is regarded as a membrane, disregarding flexural behaviors with an equilibrium analysis only is possible to estimate the distribution of the average stress across the thickness. In the cornea, the action of the intraocular pressure is supported by collagen fibrils, immersed into an elastin-proteoglycan matrix, and organized in a very precise architecture to provide the necessary confinement and transparency to the light. With the goal of understanding the static consequences of shape modifications due to pathological dilatation (ectasia), we present a simplified stress analysis of the human cornea modeled as a membrane. A numerical investigation over 40 patient-specific corneas (20 normal and 20 ectatic) is carried out to establish a relationship between the physiological geometry and the distribution of the membrane stresses, and to assess the possibility to obtain information on the stress state based on topographic images only. Comparative analyses reveal that, with respect to normal corneas, in ectatic corneas the pattern of the principal stress lines is modified markedly showing a deviation from the hypothetical dominant orientation of the collagen fibrils. The rotation of the principal stress with respect to the fibril orientation can be thought as responsible of the transmission of a large amount of shear stresses onto the elastin-proteoglycan matrix. The anomalous loading of the matrix could be correlated to the evolution of time-dependent shape modifications leading to ectasia.

scholarly journals Medical-image-based aorta modeling with zero-stress-state estimation

2019 ◽  
Vol 64 (1) ◽  
pp. 249-271 ◽  
Author(s):  
Takafumi Sasaki ◽  
Kenji Takizawa ◽  
Tayfun E. Tezduyar
Keyword(s):  
Stress State ◽  
State Estimation ◽  
Medical Image

2A23 Arterial Wall Modeling and Medical Image Mapping Based on Element-Based Zero-Stress State Estimation Method

2015 ◽  
Vol 2015.27 (0) ◽  
pp. 315-316
Author(s):  
Takafumi SASAKI ◽  
Kenji TAKIZAWA ◽  
Keiichi ITATANI ◽  
Hirokazu TAKAGI ◽  
Tayfun E. Tezduyar ◽  
...  
Keyword(s):  
Stress State ◽  
State Estimation ◽  
Medical Image ◽  
Arterial Wall ◽  
Estimation Method ◽  
Image Mapping

scholarly journals A novel medical image data-based multi-physics simulation platform for computational life sciences

2013 ◽  
Vol 3 (2) ◽  
pp. 20120058 ◽  
Author(s):  
Esra Neufeld ◽  
Dominik Szczerba ◽  
Nicolas Chavannes ◽  
Niels Kuster
Keyword(s):  
Treatment Planning ◽  
Medical Image ◽  
Life Sciences ◽  
Image Data ◽  
Human Anatomy ◽  
Simulation Platform ◽  
Anatomical Models ◽  
Wide Range ◽  
Physics Simulation ◽  
Medical Image Data

Simulating and modelling complex biological systems in computational life sciences requires specialized software tools that can perform medical image data-based modelling, jointly visualize the data and computational results, and handle large, complex, realistic and often noisy anatomical models. The required novel solvers must provide the power to model the physics, biology and physiology of living tissue within the full complexity of the human anatomy (e.g. neuronal activity, perfusion and ultrasound propagation). A multi-physics simulation platform satisfying these requirements has been developed for applications including device development and optimization, safety assessment, basic research, and treatment planning. This simulation platform consists of detailed, parametrized anatomical models, a segmentation and meshing tool, a wide range of solvers and optimizers, a framework for the rapid development of specialized and parallelized finite element method solvers, a visualization toolkit-based visualization engine, a P ython scripting interface for customized applications, a coupling framework, and more. Core components are cross-platform compatible and use open formats. Several examples of applications are presented: hyperthermia cancer treatment planning, tumour growth modelling, evaluating the magneto-haemodynamic effect as a biomarker and physics-based morphing of anatomical models.

Short Stress State Questionnaire

2015 ◽  
Vol 31 (1) ◽  
pp. 20-30 ◽  
Author(s):  
William S. Helton ◽  
Katharina Näswall
Keyword(s):  
Stress State ◽  
Factor Structure ◽  
Human Performance ◽  
Self Report ◽  
Confirmatory Factor ◽  
Stress States ◽  
Related Stress ◽  
Using Data ◽  
Task Conditions ◽  
Multiple Samples

Conscious appraisals of stress, or stress states, are an important aspect of human performance. This article presents evidence supporting the validity and measurement characteristics of a short multidimensional self-report measure of stress state, the Short Stress State Questionnaire (SSSQ; Helton, 2004 ). The SSSQ measures task engagement, distress, and worry. A confirmatory factor analysis of the SSSQ using data pooled from multiple samples suggests the SSSQ does have a three factor structure and post-task changes are not due to changes in factor structure, but to mean level changes (state changes). In addition, the SSSQ demonstrates sensitivity to task stressors in line with hypotheses. Different task conditions elicited unique patterns of stress state on the three factors of the SSSQ in line with prior predictions. The 24-item SSSQ is a valid measure of stress state which may be useful to researchers interested in conscious appraisals of task-related stress.

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