1,436 research outputs found
Motor unit discharge characteristics in response to serotonin receptor blockade in healthy humans
No full textAll motor commands from the brain ultimately synapse on the motoneurones in the spinal cord to regulate the timing and amplitude of muscle contractions. The input-output relationship between command signals and motoneuron activation is relatively simple, whereby increases in the firing rate of the command signal cause a greater output response of the motoneuron. However, a complex parallel neuromodulation system is also present, where brainstem pathways release serotonin, otherwise known as 5-hydroxytryptamine (5-HT) in the central nervous system (CNS) to regulate the gain of motoneuron activity. The purpose of this project was to determine if serotonergic effects associated with muscle activation are dependent on the mode of contraction being performed. Healthy young adults were recruited into this study, where motor unit activity was extracted from high density electromyography (HDEMG) collected from the tibialis anterior during isometric dorsiflexion. Three modes of contractions were assessed: a rapid contraction to 30% maximal voluntary contraction (MVC), a slow ramped contraction to 30% MVC, and a sustained fatiguing contraction at 30% MVC that was held to failure. Each participant was tested under normal conditions (placebo) and a condition where 5-HT2A receptors were blocked in the CNS using cyproheptadine. The main finding of the project was that a blockade of 5-HT2A receptors suppressed discharge rate of motor units during a fatiguing isometric 30% MVC contraction of the tibialis anterior muscle. In contrast, there were no drug-related differences when examining the effects of 5-HT2A antagonism for shorter contraction times that were based on rapid contractions or slow ramped contractions to achieve a steady state. It is likely that the prolonged contraction evoked more release of 5-HT into the CNS compared to the shorter duration contractions, and cyproheptadine reduced the ability of 5-HT to excite motoneurons. This project provides a valuable foundation for future research that assessed pharmacological 3 intervention and motor function, as well as research that uses HDEMG to assess motor unit activity for submaximal contractions.Thesis (Masters)Master of Medical Research (MMedRes)School of Pharmacy & Med SciGriffith HealthFull Tex
Ensuring Corporate Misconduct: How Liability Insurance Undermines Shareholder Litigation
No full textShareholder litigation and class action suits play a key role in protecting investors and regulating big businesses. But Directors and Officers liability insurance shields corporations and their managers from the financial consequences of many illegal acts, as evidenced by the recent Enron scandal and many of last year’s corporate financial meltdowns. Ensuring Corporate Misconduct demonstrates for the first time how corporations use insurance to avoid responsibility for corporate misconduct, dangerously undermining the impact of securities laws. As Tom Baker and Sean J. Griffith demonstrate, this need not be the case. Opening up the formerly closed world of corporate insurance, the authors interviewed people from every part of the industry in order to show the different instances where insurance companies could step in and play a constructive role in strengthening corporate governance—yet currently do not. Ensuring Corporate Misconduct concludes with a set of readily implementable reforms that could significantly rehabilitate the system
Activate-CP: Let's Ride a Bike! Efficacy of a functional-electrical-stimulation cycling, adapted cycling and goal-directed training program for children with cerebral palsy
No full textBackground: Advances in modern medicine and a proliferation of high-quality research focused on the prevention, diagnosis and early intervention for children with Cerebral Palsy (CP) have led to remarkable declines in the incidence and severity of CP in high income countries over the past decade. The result is less children are being born with CP and the severity of motor impairments and associated conditions are decreasing. There is, however, more work to be done to develop safe and effective rehabilitative interventions for children living with CP who are marginally ambulant or non-ambulant (Gross Motor Function Classification Scale (GMFCS) levels III-V).
Some children with CP experience declining gross motor function as they transition from childhood to adolescence, resulting in the loss of ability to perform sit-to-stand (STS) transfers, ambulate or participate in leisure activities. Goal-directed training approaches to improve gross motor function in children with CP are substantiated by high quality evidence, with a strong focus on ambulant children (GMFCS I-III). Adapted cycling is part of a burgeoning area of interest for healthcare workers who are committed to finding safe and inclusive modes of exercise for children with CP across all GMFCS levels. It can be difficult, however, for some children to self-propel on an adapted bike, and the efficacy of cycling to improve gross motor function is unclear. Functional Electrical Stimulation (FES) cycling is a novel technology that may provide opportunities for children with CP to strengthen their lower limbs, improve functional independence and increase their capacity to cycle on an adapted bike in the community. In light of the scarcity of evidence-based rehabilitative interventions appropriate for both ambulant and non-ambulant children with CP, a program of goal-directed training, FES-cycling and adapted cycling was developed.
Aim: This doctoral program aimed to: (i) determine the efficacy of cycling-based interventions to improve functional outcomes in children aged 2-18 years (GMFCS levels I-V); (ii) design an intervention of goal-directed training, FES-cycling and adapted cycling based on current evidence (Activate-CP); (iii) test the efficacy of Activate-CP to improve gross motor function, goal performance and satisfaction in children with CP compared to usual care; (iv) determine if functional improvements gained during Activate-CP training could be retained, eight weeks after completing the training, and (v) explore the experiences of participants and parents in the Activate-CP training program.
Methods: A systematic review and meta-analysis was completed to inform the development of Activate-CP: an eight-week program of goal-directed training, FES-cycling and adapted cycling. A waitlist randomized controlled trial (RCT) protocol was designed and implemented to test the efficacy of Activate-CP to improve gross motor function, goal performance and satisfaction in ambulant and non-ambulant children with CP (GMFCS II-IV), aged 6-18 years old. Participants were randomized to the intervention group (n=11) who commenced Activate-CP training immediately, or a waitlist control group (n=10). Outcomes were assessed at baseline, post-training and at eight-weeks post-training (follow-up). Primary outcomes were gross motor function assessed by the Gross Motor Function Measure (GMFM) and goal performance/satisfaction assessed by the Canadian Occupational Performance Measure (COPM). Secondary outcome measures included the five times sit-to-stand test (FTSTS), Pediatric Evaluation of Disability Index (PEDI-CAT), Participation and Environment Measure-Children and Youth (PEM-CY) and cycling power output and resistance. Pre-training, post-training and follow-up data from both groups were pooled to investigate retention of effects at eight-weeks follow-up. Semi-structured interviews were conducted at the end of Activate-CP and a thematic analysis undertaken to explore participant’s experiences.
Results: A systematic review identified nine studies (N=282) on cycling interventions for children with CP and suggested that cycling may improve muscle strength (effect size (ES): 0.77-0.93), cardiorespiratory function (ES: 1.13-1.77) and gross motor function (ES: 0.91) in children with CP. Studies were limited by small sample sizes and a lack of follow-up testing and focused predominantly on stationary cycling among ambulant children. The Activate-CP RCT was designed, developed, and delivered to 21 participants (intervention group n=11; waitlist group n=10). The intervention group had significant and clinically meaningful improvements on the GMFM (MD=7.7, 95% CI 2.3-12.6; p=0.007), COPM (MD=4.4; 95% CI 3.9-5.3; p<0.001;ES=3.32), and peak cycling resistance (MD=3.4; 95% CI 1.0-5.8; p=0.009) immediately post-training compared to the waitlist group. There were no significant between-group differences immediately post-training on secondary outcomes. Participants retained meaningful improvements on the GMFM and COPM that were higher than baseline values at eight-weeks follow up. Improvements in cycling power output and resistance, PEDICAT daily activities, PEMCY environmental barriers and FTSTS were also retained at follow-up. A thematic analysis of 17 interviews with participants (n=11) and their carers’ (n=18) revealed four major themes: facilitators and challenges to program engagement; perceived outcomes; the FES-cycling experience; and previous cycling participation.
Conclusion: Activate-CP was effective to improve gross motor function, goal performance and satisfaction and peak cycling resistance in ambulant and non-ambulant children with CP, and improvements were retained in the short term. Findings reported in this thesis support Activate-CP as a new and alternative intervention to improve functional outcomes in children with CP. Facilitators and challenges to participant engagement were identified and hold practical relevance for clinicians who work with children with CP who have goals to improve functional independence or cycling. Environmental and personal factors should be carefully considered when developing future rehabilitation programs for ambulant and non-ambulant children with CP, to maximise opportunities for success.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School Allied Health SciencesGriffith HealthFull Tex
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Ensuring Corporate Misconduct: How Liability Insurance Undermines Shareholder Litigation
No full textShareholder litigation and class action suits play a key role in protecting investors and regulating big businesses. But Directors and Officers liability insurance shields corporations and their managers from the financial consequences of many illegal acts, as evidenced by the recent Enron scandal and many of last year’s corporate financial meltdowns. Ensuring Corporate Misconduct demonstrates for the first time how corporations use insurance to avoid responsibility for corporate misconduct, dangerously undermining the impact of securities laws. As Tom Baker and Sean J. Griffith demonstrate, this need not be the case. Opening up the formerly closed world of corporate insurance, the authors interviewed people from every part of the industry in order to show the different instances where insurance companies could step in and play a constructive role in strengthening corporate governance—yet currently do not. Ensuring Corporate Misconduct concludes with a set of readily implementable reforms that could significantly rehabilitate the system
Application of Tridentate Schiff Base Chromium (III) Complex Catalysts Towards the Total Synthesis of (-)- Lasonolide A and C-Disaccharide Mimics
No full textThis thesis describes the synthetic studies performed utilizing tridentate Schiff base Cr(III) complex catalysts towards the total synthesis of ()-lasonolide A resulting in the completion of synthetic efforts towards the C17-C25 segment. Further summarization is also given on completion of the C7-C16 segment and an overview of future directions toward to the total synthesis of ()-lasonolide A. Both tetrahydropyrans C7-C11 and C19-C23 were to be constructed utilising an asymmetric hetero-Diels–Alder protocol involving Jacobsen’s hetero-Diels–Alder catalyst providing a means to generate a number of the desired stereocentres simultaneously in each ring system, followed by novel macrolide formation using ruthenium catalysts for metathesis olefination and Alder-ene chemistry. Jacobsen's hetero-Diels–Alder catalyst has also been utilised to generate C-disacharide linked precursors under diastereolective control in an effort to generate stereospecific 13 linked disaccharides.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Biomolecular and Physical SciencesScience, Environment, Engineering and TechnologyFull Tex
Griffith Criterion for Brittle Fracture in Graphene
No full textThere are prevailing concerns with the critical dimensions when conventional theories break down. Here we find that the Griffith criterion remains valid for cracks down to 10 rim but overestimates the strength of shorter cracks. We observe the preferred crack extension along the zivag edge in graphene, and explain this phenomenon by local strength-based failure rather, than energy-based Griffith criterion. These results provide a mechanistic basis for reliable applications of graphene in miniaturized: devices and nanocomposites
Recommended from our members
Ensuring Corporate Misconduct: How Liability Insurance Undermines Shareholder Litigation
No full textShareholder litigation and class action suits play a key role in protecting investors and regulating big businesses. But Directors and Officers liability insurance shields corporations and their managers from the financial consequences of many illegal acts, as evidenced by the recent Enron scandal and many of last year\u27s corporate financial meltdowns. Ensuring Corporate Misconduct demonstrates for the first time how corporations use insurance to avoid responsibility for corporate misconduct, dangerously undermining the impact of securities laws. As Tom Baker and Sean J. Griffith demonstrate, this need not be the case. Opening up the formerly closed world of corporate insurance, the authors interviewed people from every part of the industry in order to show the different instances where insurance companies could step in and play a constructive role in strengthening corporate governance - yet currently do not. Ensuring Corporate Misconduct concludes with a set of readily implementable reforms that could significantly rehabilitate the syste
Futuring Design: Transforming Interior Design using Design Futures Theory
No full textDesign studies traditionally examine the process of design in the context of how that process contributes to the creation of the designed object, system or structure. That is, a successful design process is measured by the capacity and efficiency with which it results in an object, space or system. In many cases, there is no measure of how well-designed these outputs are, at most; such measures will generally be limited to cost, efficacy and user satisfaction. Further, the notion of what constitutes well-designed is arbitrary and inconsistent across disciplines. The theory of Design Futures highlights the crucial implications of design on society and the environment in which the designed object operates over its lifetime. This thesis deals with the challenge of finding ways to incorporate the principles of Design Futures to improve design practice so that it incorporates both the lessons learned from historical enquiry and the experience of design practitioners who have attempted to incorporate these historical lessons. Inevitably, any attempt to improve design practice must engage with education practice to ensure that designers acquire the principles and methods of design which they apply in their professional practice.
Human-centred design focuses on the impact of the design on the user as they make use of the space, dwelling or object that has been designed and Design Thinking facilitates this by framing the problem as broadly and contextually as possible and iteratively reviewing the design approach with the user. Design Futures is one of a number of theories, or movements, that extends the context to the long term social, environmental and cultural implications of the design. This research builds on that work to discover a framework that connects theory to practice and how that framework might be used in educating designers to embed that theory into their practice thereby assisting them to take responsibility for the long term cultural, social and environmental implications of their design.
This research sets out to link the theory and the practice by creating a Design Futures framework and integrating it into the curriculum of an Interior Design course. This challenges the superficial view of Interior Design with a view to teaching a socially responsible design practice that takes a long-term view. Such a curriculum is built on the theoretical underpinnings of Design Futures and is informed by the key principle that a designer is responsible for the social, cultural and environmental impact of their design. The term sustainability is used in this research to include these impacts over the long-term.
This review unfolds in a narrative that moves from the literature review of Interior Design theory and practice in chapter one to an analysis of Urban Planning and its social impacts in chapter two. This second phase combines the literature review with interviews to explore the mechanics of change through an examination of the theory and practice of Urban Planning. The chapter on Authenticity extracts and examines a framework based on the variables of success developed by Price Waterhouse Coopers and summarised by the Greater Namoi Chamber of Commerce, to determine criteria for urban planners to measure the “Success of the City.”
Interviews were carried out with the founder and residents of Common Ground and with the urban planners commenting on authenticity. The practitioners actively engaged in the research as they commented on the value of authenticity as a framework for measuring the impact of gentrification as well as on the authenticity of their practice.
Given the apparent power of a framework to record and collate quantitative action research, these frameworks are then examined and compared with the Authenticity framework, to create the proposed Design Futures framework. This framework is then tested against Action Research previously undertaken by the author to explore its aptness for measuring Design Thinking and ways in which it might be employed pedagogically.
There are two separate sets of Action Research used to retrospectively review the Design Futures framework. Firstly, the author and colleagues undertook major external projects applying Design Futures theory to refine, develop and promote it. In addition, the students engaged in delivering design projects to real-world clients by applying Design Futures methodology and so were actively engaged in developing and testing the concepts that were later incorporated as the components of the Design Futures framework developed in this thesis.
By working with the students to refine and test the application of Design Futures theory, the research actively engages the students as participants in the research that they are applying. By developing the framework and the Action Research independently but from the same underpinning theory, it is possible that built in assumptions have been reinforced rather than exposed. Methods for overcoming this weakness are addressed in the conclusion.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)Queensland College of ArtArts, Education and LawFull Tex
Motor Unit Discharge Characteristics in People with Multiple Sclerosis During an Unfatigued and Fatigued Muscle Contraction Task
No full textIntroduction: Multiple sclerosis (MS) is a chronic autoimmune disease that leads to inflammation, demyelination, and neurodegeneration in the central nervous system, causing damage to both white and grey matter. This disruption affects motor and sensory pathways, leading to a wide range of physical and cognitive impairments. Fatigue is the most commonly reported symptom in MS, significantly impacting daily life and exercise adherence. The underlying causes of MS-related fatigue are complex, involving central mechanisms such as impaired signal propagation and axonal loss. Understanding motor unit behaviour, particularly during fatigue, offers valuable insights into central nervous system dysfunction in MS and could improve treatment approaches for MS-related fatigue.
Methods: 11 people with MS (mean age = 44 ± 9) and 11 age- and gender-matched controls participated in this study. Participants attended a 2 hour in-person testing session at the Neural Basis of Movement Laboratory at Griffith University on the Gold Coast. During testing, participants completed two fatigue questionnaires (the Fatigue Severity Scale and Modified Fatigue Impact Scale), four clinical tests (6-minute walk test, timed sit to stand test, stair climb test and wall squat hold), and a series of isometric knee extension contractions. During the isometric knee extension tasks, high density electromyography (HD-EMG) data was recorded from the vastus lateralis muscle of the participant's dominant leg. Participants were required to complete voluntary knee extensions at 30%, 50% and 70% of their maximal voluntary contraction. These contractions were completed in an unfatigued state and then again following a task designed to induce fatigue to the muscle.
Results: Compared to healthy controls, participants with MS exhibited reduced maximal knee extension (~10-50%) torque, significantly poorer outcomes on all clinical tests, and reported higher levels of fatigue in the questionnaires. Motor unit analysis from HD-EMG data revealed that discharge rate increased with increasing contraction intensity across both the control and MS groups, and decreased after the introduction of motor fatigue. Spike count was significantly lower for the MS group compared to the control group in the presence of motor fatigue. Spike variability was significantly higher for the MS group (~200%) compared to the control group in the presence of motor fatigue. Notably, individuals with MS showed increased motor unit coherence in the 0-5 Hz delta band, indicative of volitional force control, as well as in the 5-15 Hz alpha and 15-35 Hz beta bands, associated with afferent input regulation and descending motor commands, respectively. Furthermore, following correlative analysis, the combination of clinical tests used in this study were able to explain 23.57% of the coefficient of variation of the interspike interval and 32.76% of mean motor unit discharge characteristics in people with MS.
Discussion: In this study, people with MS demonstrated reduced motor unit discharge rates, reduced torque steadiness, and higher exertion perception during submaximal and fatiguing contractions compared to healthy controls. Intra-muscular coherence analysis revealed altered synaptic input contributions, with MS showing coherence in the 5-15 Hz alpha and 15-35 Hz beta bands. While clinical tests had little impact on baseline discharge rates, this study found that while the selected clinical tests have little relationship to the variance in baseline motor unit discharge rate, there is some predictive value when examining fatigued discharge rates and baseline coefficient of variation of the interspike interval.Thesis (Masters)Master of Medical ResearchSchool of Pharmacy and Medical SciencesGriffith HealthFull Tex
Visually Communicating Climate Change Adaptation to Children is Serious Fun!
No full textThe serious and imminent threat of anthropogenic induced climate change, and the inaction of decision makers, is driving the increasing concern children have for their future. The most prominent manifestation of this concern can be observed by children’s participation in global school strikes as students cry in the streets to have their voices heard. Since these protests, a growing demand to find novel approaches that communicate, and support children’s engagement in climate change adaptation has never been more significant. This demand reflects that children are placed outside of adaptation discourses and emphasises that children deserve to participate and author visions for their future. In response, the focus of this thesis is to experiment with creative outcomes that engage children in conversations about adaptation from a critical visual communication design perspective. The outcomes in this research experiment with games that have many unique affordances for participation where the seriousness of climate change can be approached in a playful engagement. This thesis will include practice-based research located at the nexus of community-based adaptation, critical visual communication design and serious fun. This includes the Design Away Carbon Challenge, which opened Australia’s largest one-day educational event, the Future BNE Challenge in March 2019, and the Play to Adapt game, which was included in a classroom workshop with grade seven students at the Queensland Academy of Science, Mathematics and Technology. These two events are documented in this thesis and described using semi-structured interview with facilitators, participant observations and images of the events. The creative experiments are also informed by a critical visual discourse analysis on 25 climate change adaptation frameworks. This explored how climate change adaptation discourses are visualised and identifies methods of visually communicating transformational adaptation which seeks to disrupt current visual discourses. The contribution this research has reaches beyond the design field and has implications for education, government, and non-government organisations or anyone who is seeking to engage children in the climate crisis. The imperative for this research, and any other research exploring methods of communicating climate change adaptation to children, is growing immensely as we have come to understand the implications climate change has for humans and the worlds we have created.Thesis (Masters)Master of Arts Research (MARes)Queensland College of ArtArts, Education and LawFull Tex
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