Micromechanics-Based Modeling of Biological Tissues Using the High-Fidelity Generalized Method of Cells

2004 ◽  
Vol 844 ◽  
Author(s):  
Marek-Jerzy Pindera
Keyword(s):  
Fundamental Problem ◽  
Biological Tissues ◽  
High Fidelity ◽  
Chordae Tendineae ◽  
Micromechanics Model ◽  
Deformation Regime ◽  
Generalized Method Of Cells ◽  
Infinitesimal Deformations ◽  
The Individual ◽  
Bio Engineering

ABSTRACTThe fundamental problem of micromechanics is the prediction of overall response of a composite material given the properties or response of the individual constituents and their internal geometric arrangement. The recently developed High-Fidelity Generalized Method of Cells is a promising micromechanics model whose predictive capability has been demonstrated for infinitesimal deformations in the presence of inelastic constituent behavior. The extension of this micromechanics model to the finite-deformation regime and incorporation of the quasi-linear viscoelasticity theory for the constituent response extends the range of this model's applicability to the bio-engineering area. Herein, an application involving the response of mitral valve chordae tendineae is presented that demonstrates the model's capability to mimic experimentally-observed response of this class of biological tissues rooted in their characteristic microstructures.

scholarly journals Modelling Polycrystalline Materials: An Overview of Three-Dimensional Grain-Scale Mechanical Models

2013 ◽  
Vol 05 (01) ◽  
pp. 1350002 ◽  
Author(s):  
I. Benedetti ◽  
F. Barbe
Keyword(s):  
Three Dimensional ◽  
Constitutive Modelling ◽  
Polycrystalline Materials ◽  
High Fidelity ◽  
Computational Capability ◽  
Mechanical Models ◽  
Three Dimensional Models ◽  
The Individual ◽  
Individual Grains ◽  
Micro Structures

A survey of recent contributions on three-dimensional grain-scale mechanical modelling of polycrystalline materials is given in this work. The analysis of material micro-structures requires the generation of reliable micro-morphologies and affordable computational meshes as well as the description of the mechanical behavior of the elementary constituents and their interactions. The polycrystalline microstructure is characterized by the topology, morphology and crystallographic orientations of the individual grains and by the grain interfaces and microstructural defects, within the bulk grains and at the inter-granular interfaces. Their analysis has been until recently restricted to two-dimensional cases, due to high computational requirements. In the last decade, however, the wider affordability of increased computational capability has promoted the development of fully three-dimensional models. In this work, different aspects involved in the grain-scale analysis of polycrystalline materials are considered. Different techniques for generating artificial micro-structures, ranging from highly idealized to experimentally based high-fidelity representations, are briefly reviewed. Structured and unstructured meshes are discussed. The main strategies for constitutive modelling of individual bulk grains and inter-granular interfaces are introduced. Some attention has also been devoted to three-dimensional multiscale approaches and some established and emerging applications have been discussed.

scholarly journals An individual-based mechanical model of cell movement in heterogeneous tissues and its coarse-grained approximation

2018 ◽  
Author(s):  
R. J. Murphy ◽  
P. R. Buenzli ◽  
R. E. Baker ◽  
M. J. Simpson
Keyword(s):  
Mechanical Model ◽  
Numerical Solutions ◽  
Cell Movement ◽  
Biological Tissues ◽  
Tissue Level ◽  
Cellular Level ◽  
Coarse Grained ◽  
Mechanical Heterogeneity ◽  
Single Scale ◽  
The Individual

AbstractMechanical heterogeneity in biological tissues, in particular stiffness, can be used to distinguish between healthy and diseased states. However, it is often difficult to explore relationships between cellular-level properties and tissue-level outcomes when biological experiments are performed at a single scale only. To overcome this difficulty we develop a multi-scale mathematical model which provides a clear framework to explore these connections across biological scales. Starting with an individual-based mechanical model of cell movement, we subsequently derive a novel coarse-grained system of partial differential equations governing the evolution of the cell density due to heterogeneous cellular properties. We demonstrate that solutions of the individual-based model converge to numerical solutions of the coarse-grained model, for both slowly-varying-in-space and rapidly-varying-in-space cellular properties. Applications of the model are discussed, including determining relative cellular-level properties and an interpretation of data from a breast cancer detection experiment.

scholarly journals Structure and mechanics of aegagropilae fiber network

2017 ◽  
Vol 114 (18) ◽  
pp. 4607-4612 ◽  
Author(s):  
Gautier Verhille ◽  
Sébastien Moulinet ◽  
Nicolas Vandenberghe ◽  
Mokhtar Adda-Bedia ◽  
Patrice Le Gal
Keyword(s):  
Mechanical Response ◽  
Posidonia Oceanica ◽  
Biological Tissues ◽  
Individual Response ◽  
Fiber Network ◽  
Friction Forces ◽  
Fiber Clustering ◽  
Wide Range ◽  
Natural Aggregates ◽  
The Individual

Fiber networks encompass a wide range of natural and manmade materials. The threads or filaments from which they are formed span a wide range of length scales: from nanometers, as in biological tissues and bundles of carbon nanotubes, to millimeters, as in paper and insulation materials. The mechanical and thermal behavior of these complex structures depends on both the individual response of the constituent fibers and the density and degree of entanglement of the network. A question of paramount importance is how to control the formation of a given fiber network to optimize a desired function. The study of fiber clustering of natural flocs could be useful for improving fabrication processes, such as in the paper and textile industries. Here, we use the example of aegagropilae that are the remains of a seagrass (Posidonia oceanica) found on Mediterranean beaches. First, we characterize different aspects of their structure and mechanical response, and second, we draw conclusions on their formation process. We show that these natural aggregates are formed in open sea by random aggregation and compaction of fibers held together by friction forces. Although formed in a natural environment, thus under relatively unconstrained conditions, the geometrical and mechanical properties of the resulting fiber aggregates are quite robust. This study opens perspectives for manufacturing complex fiber network materials.

Cloud-Based Application Integration in Virtual Enterprises

2019 ◽  
pp. 46-85 ◽  
Author(s):  
José Carlos Martins Delgado
Keyword(s):  
Information Systems ◽  
Fundamental Problem ◽  
Virtual Enterprise ◽  
Collaborative Network ◽  
Virtual Enterprises ◽  
Application Integration ◽  
Enterprise Information ◽  
Enterprise Information Systems ◽  
Integration Problem ◽  
The Individual

A key characteristic of a virtual enterprise (VE) is the heterogeneity of the applications that compose its enterprise information systems (EIS), since it builds on the EIS of the individual enterprises that are part of the collaborative network of that VE. This raises an application integration problem, which is even more serious than within any given EIS because a VE has a temporary nature, and therefore, integration requirements can change frequently. Current integration technologies, such as Web Services and RESTful APIs, solve the interoperability problem but usually entail more coupling than needed, since they require sharing data schemas between interacting applications, even if not all values of those schemas are actually used. The fundamental problem of application integration is therefore how to provide at most the minimum coupling possible while ensuring at least the minimum interoperability requirements. This chapter proposes compliance and conformance as the concepts to achieve this goal.

The high-fidelity generalized method of cells (HFGMC) micromechanics theory

2021 ◽  
pp. 261-319
Author(s):  
Jacob Aboudi ◽  
Steven Arnold ◽  
Brett Bednarcyk
Keyword(s):  
High Fidelity ◽  
Generalized Method Of Cells

Theory of Shocks About States in Static and Dynamic Economics

2021 ◽  
pp. 202-240
Keyword(s):  
Middle Class ◽  
Financial Stability ◽  
Fundamental Problem ◽  
Informal Institutions ◽  
The State ◽  
Social Conditions ◽  
Public Healthcare ◽  
Individual Values ◽  
Economic Agents ◽  
The Individual

The place of the state in the theory of shocks is predetermined by the increasing importance of the subjective component of the processes of self-movement of systemic integrities. The main problem is that the state formalizes the actions of subjects as economic agents, abstracting from social conditions that generate the individual values of a person implemented in the economy. So, the economic subject acquires its own individual values in a society with a sharp polarization of citizens' incomes, inequality of opportunities, a shrinking middle class, and an ineffective public healthcare system, as demonstrated by the coronavirus pandemic. As a result, a fundamental problem arises of the discrepancy between society and economy as well as formal and informal institutions that predetermine the opportunistic behavior of the economic subjects. Thus, the state persistently strives for financial stability in the economy, abstracting from the problems of social disunity.

Analysis of Locally Irregular Composites Using High-Fidelity Generalized Method of Cells

AIAA Journal ◽  
2003 ◽  
Vol 41 (12) ◽  
pp. 2331-2340 ◽  
Author(s):  
Marek-Jerzy Pindera ◽  
Jacob Aboudi ◽  
Steven M. Arnold
Keyword(s):  
High Fidelity ◽  
Generalized Method Of Cells

Strain Rate Effects on Structure-Property Relationship in the Rabbit Patellar Tendon

2009 ◽  
Author(s):  
Deborah Davis ◽  
John Clemmer ◽  
Jun Liao ◽  
Mark F. Horsetemeyer ◽  
Lakiesha N. Williams
Keyword(s):  
Patellar Tendon ◽  
Biological Tissues ◽  
Structure Property ◽  
Strain Rate Effects ◽  
Anterior Cruciate Ligaments ◽  
Property Relationship ◽  
Functional Capabilities ◽  
Structure Property Relationship ◽  
Anterior Cruciate ◽  
The Individual

Mechanical properties, functional capabilities, and internal structure have all been investigated in tendons. The patellar tendon, specifically, is commonly used for replacing damaged or torn anterior cruciate ligaments (ACL). Many areas of engineering and research seek to determine aspects of biological tissues that can be modeled and mimicked in making artificial constructs. A proper and adequate understanding of the macro and micro-composition and structure-property relationship is essential to computational modeling of the tissue. The behavior of the tendon as a whole is dependent on the mechanics of the individual sublevels of hierarchy in combination.

scholarly journals A One-Month Monitoring of Exposure to Solar UV Radiation of a Group of Construction Workers in Tuscany

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6035
Author(s):  
Alberto Modenese ◽  
Fabriziomaria Gobba ◽  
Valentina Paolucci ◽  
Swen Malte John ◽  
Pietro Sartorelli ◽  
...  
Keyword(s):  
Central Italy ◽  
Personal Exposure ◽  
Biological Tissues ◽  
Mean Value ◽  
Construction Workers ◽  
Solar Ultraviolet Radiation ◽  
Adverse Health Effects ◽  
Uv Irradiance ◽  
The Individual ◽  
Solar Radiation Exposure

Solar radiation exposure at work is a relevant heath risk in the construction sector. Our objective was to monitor for a full month the individual solar ultraviolet radiation (UVR) exposure of a group of three construction workers active in Siena (latitude = 43°19′ N), a town in Tuscany (Italy). We used personal electronic dosimeters “X-2012-10” (Gigahertz, Turkenfeld, Germany) to register the UV irradiance in the UVA and UVB/C regions separately and we consulted a specific database to retrieve the corresponding ambient erythemal UVR dose (cloud-free conditions). In spring, construction workers from central Italy received a quite variable UVR dose, between 0.9 standard erythemal doses (SED) and 15.6 SED/day, 5.7 on average. Considering the proportion with respect to the potential environmental exposure, personal exposure resulted between 2.7% and 31.2% of the ambient erythemal dose, with a mean value of 12.5%. Cumulatively, the three construction workers received in one working month a UVR dose of more than 120 SED. In a year, we estimated that a construction worker from Tuscany region is exposed to about 750 SED. This data demonstrates that construction workers in Italy are exposed to extremely high levels of solar UVR, with a relevant risk of developing adverse health effects related to the potential accumulation of UVR-induced damage in susceptible biological tissues, such as the skin and the eyes.

Perceptions of the Collective Other

1998 ◽  
Vol 2 (4) ◽  
pp. 243-250 ◽  
Author(s):  
Robert P. Abelson ◽  
Nilanjana Dasgupta ◽  
Jaihyun Park ◽  
Mahzarin R. Banaji
Keyword(s):  
Fundamental Problem ◽  
Group Behavior ◽  
Negative Consequences ◽  
Social Psychological ◽  
Research Focus ◽  
Individual Level ◽  
Single Person ◽  
Or Groups ◽  
The Social ◽  
The Individual

It is contended that perceptions of groups are affected by particular variables that do not apply to individuals (e.g., intragroup similarity and proximity). Importantly, the perception of outgroup threat has incomplete analogs at the individual level. Results from 3 studies support predictable distinctions between representations of individuals and of groups. Study I showed that priming of the word they produces more extreme negative judgments of the protagonist(s) in a story about 4 individuals acting jointly than in the same story with a single person acting alone. The opposite result holds for priming with the word he. Study 2, with Korean participants, demonstrates that actions by individuals or groups elicit differing preferences for redress. Individual responses (e.g., getting mad) to an individual racial insult (e.g., a snub by a waitress) are preferred to collective responses (e.g., circulating a petition), whereas the reverse preferences holdfor a group insult (e.g., taunts from a gang of White youths). In Study 3, cues to the entitivity of a group are introduced. This concept, introduced by Donald Campbell (1958), distinguishes different degrees of “groupness. ” Visual depictions of collections of unfamiliar humanoid creatures (greebles) were used to convey that they were either similar or dissimilar and either proximate or scattered. Results confirm the expectation that similarity and proximity-two entitive conditions-elicit more negative judgments of the group. Attention to other cues for entitivity may enrich social psychological views of stereotyping and prejudice by focusing on perceptions of groups as coordinated actors with the potential to bring about negative consequences. Such experiments point to the needfor greater research focus on the vastly understudied but fundamental problem of the social cognition of group behavior.

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