scholarly journals Tissue material properties and computational modelling of the human tibiofemoral joint: a critical review

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4298 ◽  
Author(s):  
Abby E. Peters ◽  
Riaz Akhtar ◽  
Eithne J. Comerford ◽  
Karl T. Bates
Keyword(s):  
Systematic Review ◽  
Mechanical Behaviour ◽  
Material Properties ◽  
Computational Models ◽  
Computational Modelling ◽  
Biological Tissues ◽  
Future Research ◽  
Fe Modelling ◽  
Tibiofemoral Joint ◽  
Tissue Material

Understanding how structural and functional alterations of individual tissues impact on whole-joint function is challenging, particularly in humans where direct invasive experimentation is difficult. Finite element (FE) computational models produce quantitative predictions of the mechanical and physiological behaviour of multiple tissues simultaneously, thereby providing a means to study changes that occur through healthy ageing and disease such as osteoarthritis (OA). As a result, significant research investment has been placed in developing such models of the human knee. Previous work has highlighted that model predictions are highly sensitive to the various inputs used to build them, particularly the mathematical definition of material properties of biological tissues. The goal of this systematic review is two-fold. First, we provide a comprehensive summation and evaluation of existing linear elastic material property data for human tibiofemoral joint tissues, tabulating numerical values as a reference resource for future studies. Second, we review efforts to model tibiofemoral joint mechanical behaviour through FE modelling with particular focus on how studies have sourced tissue material properties. The last decade has seen a renaissance in material testing fuelled by development of a variety of new engineering techniques that allow the mechanical behaviour of both soft and hard tissues to be characterised at a spectrum of scales from nano- to bulk tissue level. As a result, there now exists an extremely broad range of published values for human tibiofemoral joint tissues. However, our systematic review highlights gaps and ambiguities that mean quantitative understanding of how tissue material properties alter with age and OA is limited. It is therefore currently challenging to construct FE models of the knee that are truly representative of a specific age or disease-state. Consequently, recent tibiofemoral joint FE models have been highly generic in terms of material properties even relying on non-human data from multiple species. We highlight this by critically evaluating current ability to quantitatively compare and model (1) young and old and (2) healthy and OA human tibiofemoral joints. We suggest that future research into both healthy and diseased knee function will benefit greatly from a subject- or cohort-specific approach in which FE models are constructed using material properties, medical imagery and loading data from cohorts with consistent demographics and/or disease states.

scholarly journals Tissue material properties and computational modelling of the human knee: A critical review

2017 ◽  
Author(s):  
Abby E Peters ◽  
Riaz Akhtar ◽  
Eithne J Comerford ◽  
Karl T Bates
Keyword(s):  
Systematic Review ◽  
Finite Element ◽  
Knee Joint ◽  
Mechanical Behaviour ◽  
Material Properties ◽  
Computational Modelling ◽  
Biological Tissues ◽  
Finite Element Models ◽  
Human Knee ◽  
Tissue Material

Understanding how structural and functional alterations of individual tissues impact on whole-joint function is challenging, particularly in humans where direct invasive experimentation is difficult. Finite element computational models produce quantitative predictions of the mechanical and physiological behaviour of multiple tissues simultaneously, thereby providing a means to study changes that occur through healthy ageing and disease such as osteoarthritis. As a result significant research investment has been placed in developing such models of the human knee. Previous work has highlighted that model predictions are highly sensitive to the various inputs used to build them, particularly the mathematical definition of material properties of biological tissues. The goal of this systematic review is two-fold. First, we provide a comprehensive summation and evaluation of existing material property data for human knee joint tissues, tabulating numerical values as a reference resource for future studies. Second, we review efforts to model whole-knee joint mechanical behaviour through finite element modelling with particular focus on how studies have sourced tissue material properties. The last decade has seen a renaissance in material testing fueled by development of a variety of new engineering techniques that allow the mechanical behaviour of both soft and hard tissues to be characterised at a spectrum of scales from nano- to bulk tissue level. As a result there now exists an extremely broad range of published values for human knee tissues. However, our systematic review highlights gaps and ambiguities that mean quantitative understanding of how tissue material properties alter with age and osteoarthritis is limited. It is therefore currently challenging to construct finite element models of the knee that are truly representative of a specific age or disease-state. Consequently, recent whole-joint finite element models have been highly generic in terms of material properties even relying on non-human data from multiple species. We highlight this by critically evaluating current ability to quantitatively compare and model 1) young and old and 2) healthy and osteoarthritis human knee joints. We suggest that future research into both healthy and diseased knee function will benefit greatly from a subject- or cohort-specific approach in which finite element models are constructed using material properties, medical imagery and loading data from cohorts with consistent demographics and/or disease states.

scholarly journals Tissue material properties and computational modelling of the human knee: A critical review

2017 ◽  
Author(s):  
Abby E Peters ◽  
Riaz Akhtar ◽  
Eithne J Comerford ◽  
Karl T Bates
Keyword(s):  
Systematic Review ◽  
Finite Element ◽  
Knee Joint ◽  
Mechanical Behaviour ◽  
Material Properties ◽  
Computational Modelling ◽  
Biological Tissues ◽  
Finite Element Models ◽  
Human Knee ◽  
Tissue Material

Understanding how structural and functional alterations of individual tissues impact on whole-joint function is challenging, particularly in humans where direct invasive experimentation is difficult. Finite element computational models produce quantitative predictions of the mechanical and physiological behaviour of multiple tissues simultaneously, thereby providing a means to study changes that occur through healthy ageing and disease such as osteoarthritis. As a result significant research investment has been placed in developing such models of the human knee. Previous work has highlighted that model predictions are highly sensitive to the various inputs used to build them, particularly the mathematical definition of material properties of biological tissues. The goal of this systematic review is two-fold. First, we provide a comprehensive summation and evaluation of existing material property data for human knee joint tissues, tabulating numerical values as a reference resource for future studies. Second, we review efforts to model whole-knee joint mechanical behaviour through finite element modelling with particular focus on how studies have sourced tissue material properties. The last decade has seen a renaissance in material testing fueled by development of a variety of new engineering techniques that allow the mechanical behaviour of both soft and hard tissues to be characterised at a spectrum of scales from nano- to bulk tissue level. As a result there now exists an extremely broad range of published values for human knee tissues. However, our systematic review highlights gaps and ambiguities that mean quantitative understanding of how tissue material properties alter with age and osteoarthritis is limited. It is therefore currently challenging to construct finite element models of the knee that are truly representative of a specific age or disease-state. Consequently, recent whole-joint finite element models have been highly generic in terms of material properties even relying on non-human data from multiple species. We highlight this by critically evaluating current ability to quantitatively compare and model 1) young and old and 2) healthy and osteoarthritis human knee joints. We suggest that future research into both healthy and diseased knee function will benefit greatly from a subject- or cohort-specific approach in which finite element models are constructed using material properties, medical imagery and loading data from cohorts with consistent demographics and/or disease states.

Reframing Climate-Induced Socio-Environmental Conflicts: A Systematic Review

2020 ◽  
Author(s):  
Cesare M Scartozzi
Keyword(s):  
Climate Change ◽  
Systematic Review ◽  
Computational Models ◽  
Descriptive Statistics ◽  
Future Research ◽  
Environmental Conflicts ◽  
Changement Climatique ◽  
Social Ecological ◽  
Revisión Sistemática ◽  
Methodological Approaches

Abstract This article draws a comprehensive map of conflict climate change scholarship. It uses visualizations and descriptive statistics to trace the temporal, spatial, and topical evolution of the field of study via a bibliometric analysis of more than six hundred publications. It then proceeds to summarize findings, theoretical explanations, and methodological approaches. Overall, this systematic review shows a remarkable inconsistency of evidence among publications. As a way forward, this article recommends future research to use computational models, informed by a social-ecological perspective, to better explore the link between climate change and conflict. Resumen En este artículo se traza un mapa integral de la erudición conflictiva del cambio climático. Se utilizan visualizaciones y estadísticas descriptivas para rastrear la evolución temporal, espacial y temática del campo de estudio mediante un análisis bibliométrico de más de seiscientas publicaciones. Luego, continúa con un resumen de los hallazgos, las explicaciones teóricas y los enfoques metodológicos. En términos generales, esta revisión sistemática muestra una notable incoherencia de evidencias entre las publicaciones. En este artículo se recomiendan investigaciones a futuro para utilizar los modelos computacionales, informados con una perspectiva socioecológica, a fin de explorar mejor la conexión entre el cambio climático y los conflictos. Extrait Cet article offre une représentation complète des recherches portant sur les conflits liés au changement climatique. Il utilise des visualisations et des statistiques descriptives pour retracer l’évolution temporelle, spatiale et thématique de ce domaine d’étude via une analyse bibliométrique de plus de six cents publications. Il résume ensuite les constatations, explications théoriques et approches méthodologiques. Globalement, cette synthèse systématique montre une incohérence remarquable des preuves entre les publications. Pour aller de l'avant, cet article recommande que les recherches futures passent par des modèles informatiques éclairés par une perspective socio-écologique pour mieux explorer le lien entre le changement climatique et les conflits.

scholarly journals Estimating the Effect of Chirality and Size on the Mechanical Properties of Carbon Nanotubes Through Finite Element Modelling

2014 ◽  
Author(s):  
Muhammad Jibran Shahzad Zuberi ◽  
Volkan Esat
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Finite Element ◽  
Carbon Nanotube ◽  
Material Properties ◽  
Computational Models ◽  
Computational Modelling ◽  
Thermal And Electrical Properties ◽  
New Generation ◽  
Walled Carbon Nanotubes

Carbon nanotubes (CNTs) are considered to be one of the contemporary materials exhibiting superior mechanical, thermal and electrical properties. A new generation state-of-the-art composite material, carbon nanotube reinforced polymer (CNTRP), utilizes carbon nanotubes as the reinforcing fibre element. CNTRPs are highly promising composite materials possessing the potential to be used in various areas such as automotive, aerospace, defence, and energy sectors. The CNTRP composite owes its frontline mechanical material properties mainly to the improvement provided by the CNT filler. There are challenging issues regarding CNTRPs such as determination of material properties, and effect of chirality and size on the mechanical material properties of carbon nanotube fibres, which warrant development of computational models. Along with the difficulties associated with experimentation on CNTs, there is paucity in the literature on the effects of chirality and size on the mechanical properties of CNTs. Insight into the aforementioned issues may be brought through computational modelling time- and cost-effectively when compared to experimentation. This study aims to investigate the effect of chirality and size of single-walled carbon nanotubes (SWNTs) on its mechanical material properties so that their contribution to the mechanical properties of CNTRP composite may be understood more clearly. Nonlinear finite element models based on molecular mechanics using various element types substituting C-C bond are generated to develop zigzag, armchair and chiral SWNTs over a range of diameters. The predictions collected from simulations are compared to the experimental and computational studies available in the literature.

scholarly journals Active Inference as a Computational Framework for Consciousness

2021 ◽  
Author(s):  
Martina G. Vilas ◽  
Ryszard Auksztulewicz ◽  
Lucia Melloni
Keyword(s):  
Empirical Data ◽  
Computational Models ◽  
Computational Modelling ◽  
Process Theory ◽  
Future Research ◽  
Active Inference ◽  
Structural Validity ◽  
Computational Framework ◽  
Validity Testing ◽  
Neural Data

AbstractRecently, the mechanistic framework of active inference has been put forward as a principled foundation to develop an overarching theory of consciousness which would help address conceptual disparities in the field (Wiese 2018; Hohwy and Seth 2020). For that promise to bear out, we argue that current proposals resting on the active inference scheme need refinement to become a process theory of consciousness. One way of improving a theory in mechanistic terms is to use formalisms such as computational models that implement, attune and validate the conceptual notions put forward. Here, we examine how computational modelling approaches have been used to refine the theoretical proposals linking active inference and consciousness, with a focus on the extent and success to which they have been developed to accommodate different facets of consciousness and experimental paradigms, as well as how simulations and empirical data have been used to test and improve these computational models. While current attempts using this approach have shown promising results, we argue they remain preliminary in nature. To refine their predictive and structural validity, testing those models against empirical data is needed i.e., new and unobserved neural data. A remaining challenge for active inference to become a theory of consciousness is to generalize the model to accommodate the broad range of consciousness explananda; and in particular to account for the phenomenological aspects of experience. Notwithstanding these gaps, this approach has proven to be a valuable avenue for theory advancement and holds great potential for future research.

scholarly journals Stochastic strength prediction of masonry structures: a methodological approach or a way forward?

2020 ◽  
Vol 4 ◽  
pp. 122-129
Author(s):  
Vasilis Sarhosis ◽  
Tamas Forgacs ◽  
Jose Lemos
Keyword(s):  
Spatial Variability ◽  
Failure Mode ◽  
Mechanical Behaviour ◽  
Material Properties ◽  
Computational Models ◽  
Strength Prediction ◽  
External Loading ◽  
Masonry Structures ◽  
Material Parameters ◽  
Masonry Material

Today, there are several computational models to predict the mechanical behaviour of masonry structures subjected to external loading. Such models require the input of material parameters to describe the mechanical behaviour and strength of masonry constructions. Although such masonry material parameters are characterised by stochastic-probabilistic nature, engineers are assigning the same material properties throughout the structure to be analysed. The aim of this paper is to propose a methodology which considers material spatial variability and stochastic strength prediction for masonry structures. The methodology is illustrated on a case study covering the in-plane behaviour of a low bond strength masonry wall panel containing an opening. A 2D non-linear computational model based on the Discrete Element Method (DEM) is used. The computational results are compared against those obtained from the experimental findings in terms of failure mode and structural capacity. It is shown that computational models which consider the spatial variability of masonry material properties better predict the load carrying capacity, stiffness and failure mode of the masonry structures. These observations provide new insights into structural behaviour of masonry constructions and lead to suggestions for improving assessment techniques for masonry structures.

Computational Models

2014 ◽  
Author(s):  
Laurent Itti ◽  
Ali Borji
Keyword(s):  
Recent Progress ◽  
Computational Models ◽  
Computational Modelling ◽  
Complex Problem ◽  
Future Research ◽  
Top Down ◽  
Research Directions ◽  
Computational Approaches ◽  
Future Research Directions ◽  
The Many

This chapter reviews recent progress in computational modelling of visual attention. The authors start with early concepts and models, which have emphasized stimulus-driven guidance of attention towards salient objects in the visual world. They then present a taxonomy of the many different approaches which have emerged in recent research efforts. They then turn to the more complex problem of modelling top-down, task- and goal-driven influences on attention. While early top-down models have been more qualitative in nature, the authors describe several recent fully computational approaches that address top-down biasing in space, over features, and towards objects. This chapter finally provides an outlook and describes promising future research directions.

Telepractice for Adult Speech-Language Pathology Services: A Systematic Review

2020 ◽  
Vol 5 (1) ◽  
pp. 326-338 ◽  
Author(s):  
Kristen Weidner ◽  
Joneen Lowman
Keyword(s):  
Systematic Review ◽  
Primary Progressive Aphasia ◽  
Future Research ◽  
Service Delivery Model ◽  
Speech Language Pathology ◽  
Review Of The Literature ◽  
Research Designs ◽  
Assessment And Treatment ◽  
Language Pathology ◽  
Screening Assessment

Purpose We conducted a systematic review of the literature regarding adult telepractice services (screening, assessment, and treatment) from approximately 2014 to 2019. Method Thirty-one relevant studies were identified from a literature search, assessed for quality, and reported. Results Included studies illustrated feasibility, efficacy, diagnostic accuracy, and noninferiority of various speech-language pathology services across adult populations, including chronic aphasia, Parkinson's disease, dysphagia, and primary progressive aphasia. Technical aspects of the equipment and software used to deliver services were discussed. Some general themes were noted as areas for future research. Conclusion Overall, results of the review continue to support the use of telepractice as an appropriate service delivery model in speech-language pathology for adults. Strong research designs, including experimental control, across multiple well-described settings are still needed to definitively determine effectiveness of telepractice services.

Chasing the Anchor: A Systematic Review and Meta-analysis of Perceptual Anchoring Deficits in Developmental Dyslexia

2020 ◽  
Author(s):  
Kurt D Shulver ◽  
Nicholas A Badcock
Keyword(s):  
Systematic Review ◽  
Reading Ability ◽  
English Language ◽  
Prediction Interval ◽  
Meta Analysis ◽  
Visual Assessment ◽  
Individual Performance ◽  
Future Research ◽  
Significant Heterogeneity ◽  
Eligibility Criteria

We report the results of a systematic review and meta-analysis investigating the relationship between perceptual anchoring and dyslexia. Our goal was to assess the direction and degree of effect between perceptual anchoring and reading ability in typical and atypical (dyslexic) readers. We performed a literature search of experiments explicitly assessing perceptual anchoring and reading ability using PsycInfo (Ovid, 1860 to 2020), MEDLINE (Ovid, 1860 to 2019), EMBASE (Ovid, 1883 to 2019), and PubMed for all available years up to June (2020). Our eligibility criteria consisted of English-language articles and, at minimum, one experimental group identified as dyslexic - either by reading assessment at the time, or by previous diagnosis. We assessed for risk of bias using an adapted version of the Newcastle-Ottawa scale. Six studies were included in this review, but only five (n = 280 participants) were included in the meta-analysis (we were unable to access the necessary data for one study).The overall effect was negative, large and statistically significant; g = -0.87, 95% CI [-1.47, 0.27]: a negative effect size indicating less perceptual anchoring in dyslexic versus non-dyslexic groups. Visual assessment of funnel plot and Egger’s test suggest minimal bias but with significant heterogeneity; Q (4) = 9.70, PI (prediction interval) [-2.32, -0.58]. The primary limitation of the current review is the small number of included studies. We discuss methodological limitations, such as limited power, and how future research may redress these concerns. The variability of effect sizes appears consistent with the inherent variability within subtypes of dyslexia. This level of dispersion seems indicative of the how we define cut-off thresholds between typical reading and dyslexia populations, but also the methodological tools we use to investigate individual performance.

Impact of surgery timing for craniosynostosis on neurodevelopmental outcomes: a systematic review

2019 ◽  
Vol 23 (4) ◽  
pp. 442-454 ◽  
Author(s):  
Rachel Mandela ◽  
Maggie Bellew ◽  
Paul Chumas ◽  
Hannah Nash
Keyword(s):  
Systematic Review ◽  
Beneficial Effect ◽  
Data Extraction ◽  
Sociodemographic Factors ◽  
Future Research ◽  
Neurodevelopmental Outcomes ◽  
Age At Surgery ◽  
Data Extraction Form ◽  
Surgery Timing ◽  
Anesthetic Exposure

OBJECTIVEThere are currently no guidelines for the optimum age for surgical treatment of craniosynostosis. This systematic review summarizes and assesses evidence on whether there is an optimal age for surgery in terms of neurodevelopmental outcomes.METHODSThe databases MEDLINE, PsycINFO, CINAHL, Embase + Embase Classic, and Web of Science were searched between October and November 2016 and searches were repeated in July 2017. According to PICO (participants, intervention, comparison, outcome) criteria, studies were included that focused on: children diagnosed with nonsyndromic craniosynostosis, aged ≤ 5 years at time of surgery; corrective surgery for nonsyndromic craniosynostosis; comparison of age-at-surgery groups; and tests of cognitive and neurodevelopmental postoperative outcomes. Studies that did not compare age-at-surgery groups (e.g., those employing a correlational design alone) were excluded. Data were double-extracted by 2 authors using a modified version of the Cochrane data extraction form.RESULTSTen studies met the specified criteria; 5 found a beneficial effect of earlier surgery, and 5 did not. No study found a beneficial effect of later surgery. No study collected data on length of anesthetic exposure and only 1 study collected data on sociodemographic factors.CONCLUSIONSIt was difficult to draw firm conclusions from the results due to multiple confounding factors. There is some inconclusive evidence that earlier surgery is beneficial for patients with sagittal synostosis. The picture is even more mixed for other subtypes. There is no evidence that later surgery is beneficial. The authors recommend that future research use agreed-upon parameters for: age-at-surgery cut-offs, follow-up times, and outcome measures.

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