Study on tracheal collapsibility, compliance, and stress by considering nonlinear mechanical property of cartilage

Tracheal cartilage has been widely regarded as a linear elastic material either in experimental studies or in analytic and numerical models. However, it has been recently demonstrated that, like other fiber-oriented biological tissues, tracheal cartilage is a nonlinear material, which displays higher strength in compression than in extension. Considering the nonlinearity requires a more complex theoretical frame work and costs more to simulate. This study aims to quantify the deviation due to the simplified treatment of the tracheal cartilage as a linear material. It also evaluates the improved accuracy gained by considering the nonlinearity. Pig tracheal rings were used to exam the mechanical properties of cartilage and muscular membrane. By taking into account the asymmetric shape of tracheal cartilage, the collapse behavior of complete rings was simulated, and the compliance of airway and stress in the muscular membrane were discussed. The results obtained were compared with those assuming linear mechanical properties. The following results were found: (1) Models based on both types of material properties give a small difference in representing collapse behavior; (2) regarding compliance, the relative difference is big, ranging from 10 to 40% under negative pressure conditions; and (3) the difference in determining stress in the muscular membrane is small too: <5%. In conclusion, treating tracheal cartilage as a linear material will not cause big deviations in representing the collapse behavior, and mechanical stress in the muscular part, but it will induce a big deviation in predicting the compliance, particularly when the transmural pressure is lower than -0.5 kPa. The results obtained in this study may be useful in both understanding the collapse behavior of trachea and in evaluating the error induced by the simplification of treating the tracheal cartilage as a linear elastic material.

Nonlinear mechanical property of tracheal cartilage: A theoretical and experimental study

Background: Despite being the stiffest airway of the bronchial tree, the trachea undergoes significant deformation due to intrathoracic pressure during breathing. The mechanical properties of the trachea affect the flow in the airway and may contribute to the biological function of the lung. Method: A Fung-type strain energy density function was used to investigate the nonlinear mechanical behavior of tracheal cartilage. A bending test on pig tracheal cartilage was performed and a mathematical model for analyzing the deformation of tracheal cartilage was developed. The constants included in the strain energy density function were determined by fitting the experimental data. Result: The experimental data show that tracheal cartilage is a nonlinear material displaying higher strength in compression than in tension. When the compression forces varied from -0.02 to -0.03 N and from -0.03 to -0.04 N, the deformation ratios were 11.03±2.18% and 7.27±1.59%, respectively. Both were much smaller than the deformation ratios (20.01±4.49%) under tension forces of 0.02 to 0.01 N. The Fung-type strain energy density function can capture this nonlinear behavior very well, whilst the linear stress-strain relation cannot. It underestimates the stability of trachea by exaggerating the displacement in compression. This study may improve our understanding of the nonlinear behavior of tracheal cartilage and it may be useful for the future study on tracheal collapse behavior under physiological and pathological conditions.

Conceptualising the challenge of integrating digital technologies in pedagogy

The integration of digital technologies in pedagogy is positioned as an important change in education, but widespread innovative use of digital technologies is yet to be truly realised. The gap between the potential and the reality of digital technology integration is commonly attributed to a range of challenging extrinsic and intrinsic influences. Activity Theory (Engeström, 2009) is used to analyse challenges created by extrinsic influences (Nielsen, Miller, & Hoban, 2012); a complementary theory is needed to conceptualise intrinsic influences. System 1 and System 2 thinking theory (Kahneman, 2011) will be advanced as a conceptual framework for understanding conscious and unconscious aspects of teacher practice, particularly the interaction between innovation and teacher routine, attitudes and beliefs. Transformative Learning Theory (Mezirow, 2009) will be positioned to comprehend the nexus of extrinsic and intrinsic influences. This paper will propose how, when faced with extrinsic and intrinsic influences on innovative practice, educators can use these theories to conceptualise the challenge of integrating digital technologies in pedagogy.

Nonlinear analysis for the pre- and post-yield behaviour of a composite structure with the refined plastic hinge approach

The computational technique of the full ranges of the second-order inelastic behaviour evaluation of steel-concrete composite structure is not always sought forgivingly, and therefore it hinders the development and application of the performance-based design approach for the composite structure. To this end, this paper addresses of the advanced computational technique of the higher-order element with the refined plastic hinges to capture the all-ranges behaviour of an entire steel-concrete composite structure. Moreover, this paper presents the efficient and economical cross-section analysis to evaluate the element section capacity of the non-uniform and arbitrary composite section subjected to the axial and bending interaction. Based on the same single algorithm, it can accurately and effectively evaluate nearly continuous interaction capacity curve from decompression to pure bending technically, which is the important capacity range but highly nonlinear. Hence, this cross-section analysis provides the simple but unique algorithm for the design approach. In summary, the present nonlinear computational technique can simulate both material and geometric nonlinearities of the composite structure in the accurate, efficient and reliable fashion, including partial shear connection and gradual yielding at pre-yield stage, plasticity and strain-hardening effect due to axial and bending interaction at post-yield stage, loading redistribution, second-order P-δ and P-Δ effect, and also the stiffness and strength deterioration. And because of its reliable and accurate behavioural evaluation, the present technique can be extended for the design of the high-strength composite structure and potentially for the fibre-reinforced concrete structure.

Future learning landscapes for architectural education: Linking space, place, pedagogy, technology + context

Diversification and expansion of global higher education in the 21st century, has resulted in Learning Landscapes for architectural education that can no longer be sustained by the traditional model. Changes have resulted because of surging student numbers, extensions to traditional curricula, evolving competency standards and accreditation requirements, and modified geographical and pedagogical boundaries. The influx of available new technology has helped to democratise knowledge, transforming when, where and how learning takes place. Pressures on government funded higher education budgets highlight the need for a critical review of the current approach to the design and use of learning environments. Efficient design of physical space contributes significantly to savings in provision, management and use of facilities, while also potentially improving pedagogical quality. The purpose of this research is to identify emerging trends in the design of future Learning Landscapes for architectural education in Australasia; to understand where and how students of architecture are likely to learn, in the future context. It explores the important linkages between space, place, pedagogy, technology and context, using a multi methodological qualitative research approach. An Australasian context study will explore the Learning Landscapes of 23 Schools of Architecture across Australia, New Zealand and Papua New Guinea. The focus of this paper is on the methodology which is being employed to undertake dynamic data collection for the study. The research will be determined through mapping all forms of architectural learning environments, pedagogical approaches and contextual issues, to bridge the gap between academic theory, and architectural design practice. An initial understanding that pedagogy is an intrinsic component imbedded within the design of learning environments, will play an important role. Active learning environments which are exemplified by the architectural design studio, support dynamic project based and collaborative connected learning models. These have recently become a lot more common in disciplines outside of design and the arts. It is anticipated, therefore, that the implications for this research may well have a positive impact far beyond the confines of the architectural studio learning environment.

"It makes you think anything is possible”: Representing diversity in music theory pedagogy

This paper critiques a traditional approach to music theory pedagogy. It argues that music theory courses should draw on pedagogies that reflect the diversity and pluralism inherent in 21st century music making. It presents the findings of an action research project investigating the experiences of undergraduate students undertaking an innovative contemporary art music theory course. It describes the students’ struggle in coming to terms with a course that integrated composing, performing, listening and analysing coupled with what for many was their first exposure to the diversity of contemporary art music. The paper concludes with suggesting that the approach could be adopted more widely throughout music programs.

“Come in and look around.” Professional development of student teachers through public pedagogy in a library exhibition

This paper describes a public pedagogy project embedded into "The Global Teacher", a subject within the Bachelor of Education program for student teachers at an Australian university. The subject provides a global perspective on socio-political issues that shape education. In 2013, The Global Teacher introduced an approach that asked student teachers to create a museum-style exhibition depicting six global education themes. This exhibition was displayed in the State Library and the public were invited to engage with the installations and the student teachers who created them. Our paper describes how the project was implemented by means of close collaboration between the QUT teacher educators, curators at the State Library of Queensland (SLQ), and student groups working on visually translating their understandings of global educational issues into a public exhibition. We discuss what was learned by our students and ourselves, as teacher educators, by engaging in this public pedagogy.

Education, pedagogy and sport for development: Addressing seldom asked questions

This special issue features the growing field of Sport for Development. Importantly few questions have been raised about the educative quality of sport for development programs or the pedagogies by which they are delivered. This seems to be something of an oversight since; by definition development infers some sort of learning or educative process. This introductory paper provides an editorial commentary and summary on the papers included in this issue. We also comment on Sport for Development as a growing field of research and identify what might be some fruitful areas of research direction based on the papers included in the issue. Our reading of the papers suggest that there are important concerns related to pedagogy and educational practices in sport for development projects that stem from a dominance of neoliberal agendas, unintended though this may be. At the same time however, it is apparent that this challenge is being met head on by a growing number of researchers, and reports of this progress can be found in this issue.

R1SVM: A randomised nonlinear approach to large-scale anomaly detection

The problem of unsupervised anomaly detection arises in a wide variety of practical applications. While one-class support vector machines have demonstrated their effectiveness as an anomaly detection technique, their ability to model large datasets is limited due to their memory and time complexity for training. To address this issue for supervised learning of kernel machines, there has been growing interest in random projection methods as an alternative to the computationally expensive problems of kernel matrix construction and sup-port vector optimisation. In this paper we leverage the theory of nonlinear random projections and propose the Randomised One-class SVM (R1SVM), which is an efficient and scalable anomaly detection technique that can be trained on large-scale datasets. Our empirical analysis on several real-life and synthetic datasets shows that our randomised 1SVM algorithm achieves comparable or better accuracy to deep auto encoder and traditional kernelised approaches for anomaly detection, while being approximately 100 times faster in training and testing.

The performance in context model: A 21st century tertiary dance teaching pedagogy

Despite tertiary institutions acknowledging that reflective practice is an essential component of undergraduate dance teacher training, there is often a disparity between the tertiary students’ reflective skills and the more sophisticated reflective ability needed to navigate the 21st century workforce (Silva 2008). This paper charts the evolution of a dance teaching reflective pedagogy within a suite of three units across a three-year undergraduate dance teacher-training course for school, community and studio dance teachers. This reflective pedagogy based on exploration, collaboration, critical questioning and connections with community forms the basis of a model of tertiary dance teacher- training; the Performance in Context Model (PCM). Over the past four years, through four cycles of action research, the PCM pedagogy, context and engagement with community has developed into a successful model integrating practical dance teaching skills, artistry and community engagement. The PCM represents a holistic collaborative approach to dance teacher education: the marrying of ‘teacher-as-artist’, ‘teacher-as-performer’ and ‘teacher-as-researcher’. More specifically, it emphasises the need for mature, reflective, receptive and flexible approaches in response to dance teaching and learning. These are enacted in a variety of contexts, with tertiary dance teaching students identifying as teaching artists, as well as researchers of their own practice.

Building teachers' pedagogy practices in reasoning, to improve students' dispositions towards mathematics

Drawing on participatory action research, this study identifies the pedagogies necessary to advance reasoning, which is one of the proficiencies from the Australian Curriculum Mathematics, and explores how reasoning leads to greater productive disposition. With the current emphasis on STEM in schools, this research is timely. This thesis makes an original and substantive contribution to the understanding of why and how teachers can most effectively advance student proficiency in reasoning through targeted instructional strategies and style of instruction. The study explores the ways in which teacher practices, when focused on reasoning, enhance the disposition of students towards greater mathematical proficiency.