350 research outputs found

    Developing casual conversation skills of pre-school children learning English as a foreign language in the home context

    Full text link
    University of Technology, Sydney. Faculty of Education.The broad aim of this thesis is to investigate the development of the English conversation of two, pre-school children, who are learning English as a foreign language in the home context, by focusing on their language skills and their learning processes. In order to do this, there are two major aims: first, to describe the development of the children's English conversational language skills over a four year period, by focusing on their construction of five genres of casual conversation. And second, to describe the key learning processes involved in the development of the children's English conversational skills, in particular focusing on the role of the scaffolding process. The procedure involves the analysis of spoken data collected from the two children. The data is arranged according to genre. Data from the modeling and joint negotiation stages of the pedagogical cycle focuses on the role of the scaffolding process in the children's learning. Data from these two phases has been analyzed within the theoretical framework of sociocultural learning theory, arguing that this framework provides a description of the scaffolding process, which is fundamental to learning. Data from this phase is analyzed for mediation, contingency, the scaffolding steps, and the father's role as the teacher in the ZPD. However, data from the independent construction phase focuses on the language skills the children have independently produced, when the scaffolding has been removed. Language in this phase has been described and analyzed within the theoretical framework of systemic functional linguistics, arguing that this framework provides a systematic description of the children's conversational language. Data from this phase is analyzed for generic structure, mood and appraisal. The data set has been collected at random over a four year period. This focuses on the father's explicit teaching of five genres of casual conversation to his two daughters. The data set has been taken from the periods of explicit teaching, which occurs at set times of the day, mainly during 'dinner time talk', 'bed time talk', and 'before school study time'. In order to investigate the two aims of the thesis, the research questions focus on two main areas - questions related to the development of language skills, and questions related to the learning process. The four research questions related to the development of language skills are: • What is the extent to which the children can independently construct texts with appropriate generic structure? • What is the extent to which the children can structure their texts to reflect their speaking purposes? • What is the extent to which the children can give and exchange information appropriately within the five genres, using the interpersonal resources of mood? • What is the extent to which the children can express attitudes and take a stance by using the interpersonal resources of appraisal? The four research questions related to the learning process are: • What is the role of scaffolding in the children's learning? • What is the role of mediation in the children's learning? • What is the role of contingency in the children's learning? • What is the role of the teacher in the children's learning? The results of the study are based on the data findings in chapters 4, 5, and 6. Each text is analyzed and the findings are interpreted. Conclusions are then presented for each genre, and discussed in relation to the children's language skills and learning processes. The main conclusions of the thesis, incorporating all five genres, are presented in the final chapter. The significance of the thesis is discussed in terms of its implications for the fields of linguistics, second and foreign language education, and bilingualism. In terms of linguistics, it is argued that the thesis contributes to the descriptions and theorizing of casual conversation; for second and foreign language education, it illustrates the need for pedagogy to be based on functional and explicit theories of language and learning; and for bilingualism, it focuses on the importance of models in the development of identity. It is argued that the thesis makes a multidisciplinary contribution to each of these three academic fields. Also, by adopting an integrated theoretical stance to the data analysis, the thesis highlights the importance of providing different but complementary insights into the discourses of foreign language learning. These contributions reflect the significance of the thesis, which aims to merge language theory with learning pedagogy, relevant to children learning conversational English in a foreign language context

    Research Abstract: From Description to Practice

    Get PDF
    The purpose of this paper is to show how university students for whom English is a foreign language can be taught to write an abstract for a research paper. The paper draws on research from Systemic Functional Linguistics, in particular from genre theory (Martin, 1985; Martin & Rose, 2003; Swales, 1990; 2004; Swales & Freak, 2004; Freak & Swales, 2011). A genre-based rating scale is described that makes explicit the specific functions of each section of the abstract. Data from two student abstracts are then analyzed and interpreted, illustrating how the theory has been applied

    Coupled swelling and nematic reordering in liquid crystal gels

    Get PDF
    We derive a multiphysics model that accounts for network elasticity with spontaneous strains, swelling and nematic interactions in liquid crystal gels (LCGs). We discuss the coupling among the various physical mechanisms, with particular reference to the effects of nematic interactions on chemical equilibrium and that of swelling on the nematic-isotropic transition. Building upon this discussion and using numerical simulations, we explore the transient phenomena involving concurrent swelling and phase transition in LCGs subject to a temperature change. Specifically, we demonstrate separation in time scales between solvent uptake and phase change, in agreement with experiments, which determines a kinetic decoupling between shape and volume changes. Finally, we discuss possible applications in the context of microswimmers, where such a kinetic decoupling is exploited to achieve non-reciprocal actuation and net motion in Stokes flow

    Concurrent factors determine toughening in the hydraulic fracture of poroelastic composites

    Get PDF
    Brittle materials fail catastrophically. In consequence of their limited flaw-tolerance, failure occurs by localized fracture and is typically a dynamic process. Recently, experiments on epithelial cell monolayers have revealed that this scenario can be significantly modified when the material susceptible to cracking is adhered to a hydrogel substrate. Thanks to the hydraulic coupling between the brittle layer and the poroelastic substrate, such a composite can develop a toughening mechanism that relies on the simultaneous growth of multiple cracks. Here, we study this remarkable behaviour by means of a detailed model, and explore how the material and loading parameters concur in determining the macroscopic toughness of the system. By extending a previous study, our results show that rapid loading conveys material toughness by promoting distributed cracking. Moreover, our theoretical findings may suggest innovative architectures of flaw-insensitive materials with higher toughness. ArXI

    Equilibrium and transient response of photo-actuated Liquid Crystal Elastomer beams

    Get PDF
    Light actuation is one of the preferred and advantageous approaches to remotely induce and control deformations in soft materials such as photoactive Liquid Crystal Elastomers (LCEs). Various experimental and numerical works have been carried out in the literature to study the actuation of photoactive LCE sheets under illumination. In this study, we have developed a reduced multi-physics model to predict the equilibrium and dynamic response of photoactive LCE beams under illumination. We test our model against an experiment in which a double-clamped thin nematic LCE beam is subjected to UV light, and the stress is generated in the beam due to induced contraction under illumination. Our numerical results demonstrate reasonable agreement with the experiment regarding stress evolution trend and saturation time. We also investigate the bending response of a photoactive LCE beam subjected to UV light. Based on our parameters, we observe that the nematic beam bends towards the light only due to the photochemical strain gradient along the thickness. Finally, to test our model in a dynamic situation, we perform the simulation for the self-oscillations of an LCE beam under illumination. We show that the alternate activation of the top and bottom surfaces of the LCE beam by uniform steady illumination can pump energy into the system, resulting in the phenomenon of self-oscillations

    Swelling dynamics of a thin elastomeric sheet under uniaxial pre--stretch

    Get PDF
    It has been demonstrated experimentally that pre-stretch affects the swelling of an elastomeric membrane when it is exposed to a solvent. We study theoretically the one-dimensional swelling of a pre-stretched thin elastomeric sheet, bonded to an impermeable rigid substrate, to quantify the influence of pre-stretch. We show that the solvent uptake increases when pre-stretch increases, both at equilibrium and during the swelling transient, where it exhibits two different scaling regimes. The coupling between the solvent uptake and pre-stretch may be practically exploited to design soft actuators where the swelling-induced deformations can be controlled by varying the pre-stretch

    Mechanics of tubular helical assemblies: ensemble response to axial compression and extension

    Get PDF
    Abstract Nature and technology often adopt structures that can be described as tubular helical assemblies. However, the role and mechanisms of these structures remain elusive. In this paper, we study the mechanical response under compression and extension of a tubular assembly composed of 8 helical Kirchhoff rods, arranged in pairs with opposite chirality and connected by pin joints, both analytically and numerically. We first focus on compression and find that, whereas a single helical rod would buckle, the rods of the assembly deform coherently as stable helical shapes wound around a common axis. Moreover, we investigate the response of the assembly under different boundary conditions, highlighting the emergence of a central region where rods remain circular helices. Secondly, we study the effects of different hypotheses on the elastic properties of rods, i.e., stress-free rods when straight versus when circular helices, Kirchhoff's rod model versus Sadowsky's ribbon model. Summing up, our findings highlight the key role of mutual interactions in generating a stable ensemble response that preserves the helical shape of the individual rods, as well as some interesting features, and they shed some light on the reasons why helical shapes in tubular assemblies are so common and persistent in nature and technology. Graphic Abstract We study the mechanical response under compression/extension of an assembly composed of 8 helical rods, pin-jointed and arranged in pairs with opposite chirality. In compression we find that, whereas a single rod buckles (a), the rods of the assembly deform as stable helical shapes (b). We investigate the effect of different boundary conditions and elastic properties on the mechanical response, and find that the deformed geometries exhibit a common central region where rods remain circular helices. Our findings highlight the key role of mutual interactions in the ensemble response and shed some light on the reasons why tubular helical assemblies are so common and persistent

    Nutations in growing plant shoots: the role of elastic deformations due to gravity loading

    Get PDF
    Abstract The effect of elastic deformations induced by gravity loading on the active circumnutation movements of growing plant shoots is investigated. We consider first a discrete model (a gravitropic spring-pendulum system) and then a continuous rod model which is analyzed both analytically (under the assumption of small deformations) and numerically (in the large deformation regime). We find that, for a choice of material parameters consistent with values reported in the available literature on plant shoots, rods of sufficient length may exhibit lateral oscillations of increasing amplitude, which eventually converge to limit cycles. This behavior strongly suggests the occurrence of a Hopf bifurcation, just as for the gravitropic spring-pendulum system, for which this result is rigorously established. At least in this restricted set of material parameters, our analysis supports a view of Darwin's circumnutations as a biological analogue to structural systems exhibiting flutter instabilities, i.e., spontaneous oscillations away from equilibrium configurations driven by non-conservative loads. Here, in the context of nutation movements of growing plant shoots, the energy needed to sustain oscillations is continuously supplied to the system by the internal biochemical machinery presiding the capability of plants to maintain a vertical pose
    • …
    corecore