Parameter estimation for a phenomenological model of the cardiac action potential

The action potential (ap) of a cardiac cell is made up of a complex balance of ionic currents which flow across the cell membrane in response to electrical excitation of the cell. Biophysically detailed mathematical models of the ap have grown larger in terms of the variables and parameters required to model new findings in subcellular ionic mechanisms. The fitting of parameters to such models has seen a large degree of parameter and module re-use from earlier models. An alternative method for modelling electrically exciteable cardiac tissue is a phenomenological model, which reconstructs tissue level ap wave behaviour without subcellular details. A new parameter estimation technique to fit the morphology of the ap in a four variable phenomenological model is presented. An approximation of a nonlinear ordinary differential equation model is established that corresponds to the given phenomenological model of the cardiac ap. The parameter estimation problem is converted into a minimisation problem for the unknown parameters. A modified hybrid Nelder–Mead simplex search and particle swarm optimization is then used to solve the minimisation problem for the unknown parameters. The successful fitting of data generated from a well known biophysically detailed model is demonstrated. A successful fit to an experimental ap recording that contains both noise and experimental artefacts is also produced. The parameter estimation method’s ability to fit a complex morphology to a model with substantially more parameters than previously used is established.

Measuring driver responses at railway level crossings

Railway level crossings are amongst the most complex of road safety control systems, due to the conflicts between road vehicles and rail infrastructure, trains and train operations. Driver behaviour at railway crossings is the major collision factor. The main objective of the present paper was to evaluate the existing conventional warning devices in relation to driver behaviour. The common conventional warning devices in Australia are a stop sign (passive), flashing lights and a half boom-barrier with flashing lights (active). The data were collected using two approaches, namely: field video recordings at selected sites and a driving simulator in a laboratory. This paper describes and compares the driver response results from both the field survey and the driving simulator. The conclusion drawn is that different types of warning systems resulted in varying driver responses at crossings. The results showed that on average driver responses to passive crossings were poor when compared to active ones. The field results were consistent with the simulator results for the existing conventional warning devices and hence they may be used to calibrate the simulator for further evaluation of alternative warning systems.

Sit versus stand : can sitting be accurately identified using MTI accelerometer data?

High levels of sitting have been linked with poor health outcomes. Previously a pragmatic MTI accelerometer data cut-point (100 count/min-1) has been used to estimate sitting. Data on the accuracy of this cut-point is unavailable. PURPOSE: To ascertain whether the 100 count/min-1 cut-point accurately isolates sitting from standing activities. METHODS: Participants fitted with an MTI accelerometer were observed performing a range of sitting, standing, light & moderate activities. 1-min epoch MTI data were matched to observed activities, then re-categorized as either sitting or not using the 100 count/min-1 cut-point. Self-report demographics and current physical activity were collected. Generalized estimating equation for repeated measures with a binary logistic model analyses (GEE), corrected for age, gender and BMI, were conducted to ascertain the odds of the MTI data being misclassified. RESULTS: Data were from 26 healthy subjects (8 men; 50% aged <25 years; mean BMI (SD) 22.7(3.8)m/kg2). MTI sitting and standing data mode was 0 count/min-1, with 46% of sitting activities and 21% of standing activities recording 0 count/min-1. The GEE was unable to accurately isolate sitting from standing activities using the 100 count/min-1 cut-point, since all sitting activities were incorrectly predicted as standing (p=0.05). To further explore the sensitivity of MTI data to delineate sitting from standing, the upper 95% confidence interval of the mean for the sitting activities (46 count/min-1) was used to re-categorise the data; this resulted in the GEE correctly classifying 49% of sitting, and 69% of standing activities. Using the 100 count/min-1 cut-point the data were re-categorised into a combined ‘sit/stand’ category and tested against other light activities: 88% of sit/stand and 87% of light activities were accurately predicted. Using Freedson’s moderate cut-point of 1952 count/min-1 the GEE accurately predicted 97% of light vs. 90% of moderate activities. CONCLUSION: The distributions of MTI recorded sitting and standing data overlap considerably, as such the 100 count/min -1 cut-point did not accurately isolate sitting from other static standing activities. The 100 count/min -1 cut-point more accurately predicted sit/stand vs. other movement orientated activities.

It’s not me, it’s you : a participant observation case study of the self-publishing musician in the 21st century

This thesis explores the business environment for self-publishing musicians at the end of the 20th century and the start of the 21st century from theoretical and empirical standpoints. The exploration begins by asking three research questions: what are the factors affecting the sustainability of an Independent music business; how many of those factors can be directly influenced by an Independent musician in the day-to-day operations of their musical enterprise; and how can those factors be best manipulated to maximise the benefit generated from digital music assets? It answers these questions by considering the nature of value in the music business in light of theories of political economy, then quantitative and qualitative examinations of the nature of participation in the music business, and then auto-ethnographic approaches to the application of two technologically enabled tools available to Independent musicians. By analyzing the results of five different examinations of the topic it answers each research question with reference to four sets of recurring issues that affect the operations of a 21st century music business: the musicians’ personal characteristics, their ability to address their business’s informational needs; their ability to manage the relationships upon which their business depends; and their ability to resolve the remaining technological problems that confront them. It discusses ways in which Independent self-publishing musicians can and cannot deal with these four issues on a day-to-day basis and highlights aspects for which technological solutions do not exist as well as ways in which technology is not as effective as has been claimed. It then presents a self-critique and proposes some directions for further study before concluding by suggesting some common features of 21st century Independent music businesses. This thesis makes three contributions to knowledge. First, it provides a new understanding of the sources of musical value, shows how this explains changes in the music industries over the past 30 years, and provides a framework for predicting future developments in those industries. Second, it shows how the technological discontinuity that has occurred around the start of the 21st century has and has not affected the production and distribution of digital cultural artefacts and thus the attitudes, approaches, and business prospects of Independent musicians. Third, it argues for new understandings of two methods by which self-publishing musicians can grow a business using production methods that are only beginning to be more broadly understood: home studio recording and fan-sourced production. Developed from the perspective of working musicians themselves, this thesis identifies four sets of issues that determine the probable success of musicians’ efforts to adopt new technologies to capture the value of the musicians’ creativity and thereby foster growth that will sustain an Independent music business in the 21st century.

A nanoscratch method for measuring hardness of thin films

Thin solid films were extensively used in the making of solar cells, cutting tools, magnetic recording devices, etc. As a result, the accurate measurement of mechanical properties of the thin films, such as hardness and elastic modulus, was required. The thickness of thin films normally varies from tens of nanometers to several micrometers. It is thus challenging to measure their mechanical properties. In this study, a nanoscratch method was proposed for hardness measurement. A three-dimensional finite element method (3-D FEM) model was developed to validate the nanoscratch method and to understand the substrate effect during nanoscratch. Nanoindentation was also used for comparison. The nanoscratch method was demonstrated to be valuable for measuring hardness of thin solid films.

YouTube and the formalisation of amateur media

This chapter describes how, as YouTube has scaled up both as a platform and as a company, its business model and the consequences for its copyright regulation strategies have co-evolved, and so too the boundaries between amateur and professional media have shifted and blurred in particular ways. As YouTube, Inc moves to more profitably arrange and stabilise the historically contentious relations among rights-holders, uploaders, advertisers and audiences, some forms of amateur video production have become institutionalised and professionalised, while others have been further marginalised and driven underground or to other, more forgiving, platforms.

The effect of simulated astigmatic refractive error on reading performance

Background: Few studies have specifically investigated the functional effects of uncorrected astigmatism on measures of reading fluency. This information is important to provide evidence for the development of clinical guidelines for the correction of astigmatism. Methods: Participants included 30 visually normal, young adults (mean age 21.7 ± 3.4 years). Distance and near visual acuity and reading fluency were assessed with optimal spectacle correction (baseline) and for two levels of astigmatism, 1.00DC and 2.00DC, at two axes (90° and 180°) to induce both against-the-rule (ATR) and with-the-rule (WTR) astigmatism. Reading and eye movement fluency were assessed using standardized clinical measures including the test of Discrete Reading Rate (DRR), the Developmental Eye Movement (DEM) test and by recording eye movement patterns with the Visagraph (III) during reading for comprehension. Results: Both distance and near acuity were significantly decreased compared to baseline for all of the astigmatic lens conditions (p < 0.001). Reading speed with the DRR for N16 print size was significantly reduced for the 2.00DC ATR condition (a reduction of 10%), while for smaller text sizes reading speed was reduced by up to 24% for the 1.00DC ATR and 2.00DC condition in both axis directions (p<0.05). For the DEM, sub-test completion speeds were significantly impaired, with the 2.00DC condition affecting both vertical and horizontal times and the 1.00DC ATR condition affecting only horizontal times (p<0.05). Visagraph reading eye movements were not significantly affected by the induced astigmatism. Conclusions: Induced astigmatism impaired performance on selected tests of reading fluency, with ATR astigmatism having significantly greater effects on performance than did WTR, even for relatively small amounts of astigmatic blur of 1.00DC. These findings have implications for the minimal prescribing criteria for astigmatic refractive errors.

Perceived gender differences in STEM learning in the middle school

Women are underrepresented in science, technology, engineering and mathematics (STEM) university coursework, reflecting long-standing gender issues that have existed in core middle-school STEM subject areas. Using data from a survey and written responses, we report on findings following the introduction of engineering education in middle school classes across three schools (grade level 7, n=122). The engineering experiences fused science, technology and mathematics concepts. The survey revealed higher percentages for girls than boys in 13 of the 24 items; however there were six items with a 20% difference in their perceptions about learning in STEM. For instance, despite girls recording that they have been provided equal or more opportunities than boys in STEM, they believed they do not do as well as boys (80% boys, 48% girls) or want to seek a career in STEM (39% boys, 17% girls). The written responses revealed gender differences across a number of themes in the students’ responses, including resources, group work, the nature and type of learning experiences, content knowledge, and teachers’ instructional style. Exposing students to STEM education facilitates an awareness of their learning and may assist girls to consider studying STEM subjects or STEM careers.

The subjective experience of negative symptoms : characteristics of emotional withdrawal

According to the diagnosis of schizophrenia in the DSM-IV-TR (American Psychiatric Association, 2000), negative symptoms are those personal characteristics that are thought to be reduced from normal functioning, while positive symptoms are aspects of functioning that exist as an excess or distortion of normal functioning. Negative symptoms are generally considered to be a core feature of people diagnosed with schizophrenia. However, negative symptoms are not always present in those diagnosed, and a diagnosis can be made with only negative or only positive symptoms, or with a combination of both. Negative symptoms include an observed loss of emotional expression (affective flattening), loss of motivation or self directedness (avolition), loss of speech (alogia), and also a loss of interests and pleasures (anhedonia). Positive symptoms include the perception of things that others do not perceive (hallucinations), and extraordinary explanations for ordinary events (delusions) (American Psychiatric Association, 2000). Both negative and positive symptoms are derived from watching the patient and thus do not consider the patient’s subjective experience. However, aspects of negative symptoms, such as observed affective flattening are highly contended. Within conventional psychiatry, the absence of emotional expression is assumed to coincide with an absence of emotional experience. Contrasting research findings suggests that patients who were observed to score low on displayed emotional expression, scored high on self ratings of emotional experience. Patients were also observed to be significantly lower on emotional expression when compared with others (Aghevli, Blanchard, & Horan, 2003; Selton, van der Bosch, & Sijben, 1998). It appears that there is little correlation between emotional experience and emotional expression in patients, and that observer ratings cannot help us to understand the subjective experience of the negative symptoms. This chapter will focus on research into the subjective experiences of negative symptoms. A framework for these experiences will be used from the qualitative research findings of the primary author (Le Lievre, 2010). In this study, the primary author found that subjective experiences of the negative symptoms belonged to one of the two phases of the illness experience; “transitioning into emotional shutdown” or “recovering from emotional shutdown”. This chapter will use the six themes from the phase of “transitioning into emotional shutdown”. This phase described the experience of turning the focus of attention away from the world and onto the self and the past, thus losing contact with the world and others (emotional shutdown). Transitioning into emotional shutdown involved; “not being acknowledged”, “relational confusion”, “not being expressive”, “reliving the past”, “detachment”, and “no sense of direction” (Le Lievre, 2010). Detail will be added to this framework of experience from other qualitative research in this area. We will now review the six themes that constitute a “transition into emotional shutdown” and corresponding previous research findings.

The enterprising artist and the arts entrepreneur : Emergent pedagogies for new disciplinary habits of mind

Traditional pedagogies in the arts in higher education focus largely on the studio experience in which a novice artist studies under one or more master teachers (e.g., Don, Garvey, & Sadeghpour, 2009). In more recent times, however, a shift in higher education curriculum and pedagogy in the arts has expanded this traditional conservatory model of training to include, among other components, career self-management and enterprise creation—in a word, entrepreneurship.This chapter examines the developing field of arts enterprise and arts entrepreneurship in higher education in a multinational context. The field is contextualized within the broader landscape of the creative industries and the consequential development of knowledge, skills, and the habits of mind necessary for artistic venture creation, sustainability, and success. Whereas the discourse about learning and teaching for business entrepreneurship is well established (e.g., Fiet, 2001), equivalent conversations about arts enterprise and entrepreneurship have only recently begun (Beckman, 2007, 2011; Essig, 2009). This chapter will address the contested definitions of key terms and concepts and also the question of how arts educators, although mindful of the pedagogic traditions of the arts school, are also drawing on the pedagogies of business entrepreneurship and cognitive theories of entrepreneurship to create innovative new transdisciplinary signature pedagogies for creative enterprise and entrepreneurship education in the arts.

Closing the loop 21st century style : providing feedback on written assessment via MP3 recordings

Feedback on student performance, whether in the classroom or on written assignments, enables them to reflect on their understandings and restructure their thinking in order to develop more powerful ideas and capabilities. Research has identified a number of broad principles of good feedback practice. These include the provision of feedback that facilitates the development of reflection in learning; helps clarify what good performance is in terms of goals, criteria and expected standards; provides opportunities to close the gap between current and desired performance; delivers high quality information to students about their learning; and encourages positive motivational beliefs and self-esteem. However, high staff–student ratios and time pressures often result in a gulf between this ideal and reality. Whilst greater use of criteria referenced assessment has enabled an improvement in the extent of feedback being provided to students, this measure alone does not go far enough to satisfy the requirements of good feedback practice. Technology offers an effective and efficient means by which personalised feedback may be provided to students. This paper presents the findings of a trial of the use of the freely available Audacity program to provide individual feedback via MP3 recordings to final year Media Law students at the Queensland University of Technology on their written assignments. The trial has yielded wide acclaim by students as an effective means of explaining the exact reasons why they received the marks they were awarded, the things they did well and the areas needing improvement. It also showed that good feedback practice can be achieved without the burden of an increase in staff workload.