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Exploring the efficacy of a spatial reasoning approach to teaching and learning fractions in the early years
No full textFractions are widely recognised as one of the most difficult areas of the school mathematics curriculum to teach and learn. A deep understanding of fractions supports further learning in areas such as algebra, proportional reasoning, and statistics. In Australia, research has established that many students in the primary and middle years of schooling experience considerable difficulty in recognising, naming, and renaming common fractions. This difficulty is consistently reflected in Australian students’ results on international assessments of mathematical literacy.
One issue contributing to these difficulties, is the way in which fractions are represented in the Australian Mathematics Curriculum content descriptors. Within the early years, children are expected to recognise equal parts of a whole, primarily emphasising the part-whole meaning of fractions. This focus promotes an additive, counting-based approach to the teaching and learning of fractions. Such an approach overlooks the critical foundations fractions have in fair sharing contexts and masks the multiplicative nature of fractions.
The foundation of early fraction understanding needs to be based on fair sharing or equal partitioning. Fair sharing is an intuitive idea that very young children experience in a range of contexts before they begin school. Research on children’s early number learning suggests that fair sharing is a highly spatial activity. This is particularly evident when children share collections of items, or partition continuous objects fairly based on attributes such as geometric similarities and spatial arrangements.
Spatial reasoning and its association with mathematics achievement is well established in the literature. Although there is increasing interest in examining young children's spatial reasoning and mathematical development in general, there is very little research that has examined the role spatial reasoning may play in relation to early fraction learning. This thesis aims to address this gap in the research.
A Design-Based Research (DBR) methodology was employed, to explore the extent to which young children could demonstrate an understanding of a broader range of fraction meanings, experienced through a spatial reasoning approach. Consistent with DBR, a local instruction theory was developed to frame the design and implementation of an iterative teaching experiment that introduced children to the fraction as an operator, fraction as a measure and fraction as a relation meanings. The local instruction theory was represented by a series of conjectured key indicators that proposed a pathway for developing the three meanings of fractions through a spatial reasoning approach. The key indicators informed the design of an intervention program comprising of 13 consecutive 60-minute lessons, which were implemented with 70, Year 1 and 2 children at three primary schools in regional South Australia. In its final form, the four key indicators of the local instruction theory were: creating and justifying equal shares; reinitialising the unit; recognising proportional equivalence and connecting multiplicative relations.
The results of the study revealed that young children developed rich understandings of the three meanings of fractions, which were directly supported by spatial reasoning. The children demonstrated an understanding of the fraction as an operator meaning, through a focus on spatial visualisation to predict and justify the outcome of sharing geometric shapes, and small collections of objects. The children developed the fraction as a measure meaning specifically in the way they were able to work with unit fractions, composite units, and their ability to name different fraction parts. Spatial structuring was a critical construct that supported the children’s ability to make connections about the associated fraction as a measure ideas, and fraction magnitude. Further, the children demonstrated an ability to recognise fraction and proportional equivalence, through contexts that developed their spatial proportional reasoning. The children were able to work with early fraction as a relation ideas, specifically simple ratio, which was supported by spatial structuring. Additionally, the influence of spatial structuring within fraction as a relation contexts, positively influenced children’s part-part relations for whole number quantities.
Another critical finding of this study was the way in which children used gesture to communicate both spatial and mathematical knowledge. The children's spontaneous use of gesture throughout the intervention provided greater insights into their use of spatial reasoning strategies, and how these were connected to their understanding of fractions. This is an important finding that makes a significant contribution to what is currently known about how young children use self-initiated gestures to explain and communicate their mathematical thinking.
As the three meanings of fractions are not typically taught or considered to be entirely appropriate for children in the early years, this study challenges the foundations of the current curriculum expectations that promote additive approaches to learning fractions. The findings provide powerful insights into what is possible in the early years of schooling. Specifically, the ability for children to develop a multiplicative foundation for an extended range of fraction meanings, though a spatial reasoning approach. Given the persistent difficulties children in the middle and upper years of primary education experience with fractions, an explicit emphasis on spatial reasoning in the early years of school provides an important alternative approach to the teaching and learning of factions
Investigation of the magneto-conductivity of topological materials
No full textTopological materials (TMs) have attracted wide attention from the scientific community due to their unique band structure. Applications exist for these materials in the fields of spintronics, memory devices and quantum computing. Among TMs, topological insulators (TIs) have arguably received the most attention and exhibit both insulating bulk states and conducting surface states (SS). The latter are protected by time-reversal symmetry (TRS). Dirac semimetals (DSMs) is another class that are characterized by the presence of Dirac cones with tilted dispersion relations and have been studied with potential applications in next generation electronic devices foreseen. The transport properties of these materials can reveal various physical parameters, such as charge carrier mobilities, residual resistance, conductivity, magnetoresistance (MR), as well as their temperature and magnetic field dependence. The SS can be probed by performing angle-resolved photoemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM) measurements. However, an indirect way to probe these topological surface states (TSS) is to study the impact of the applied magnetic field and temperature on the magneto-transport properties of TMs using a physical property measuring system (PPMS).
In this dissertation, measurements and analysis of TIs and DSMs are reported. Single crystals of these materials were grown by a solid-state reaction route using different heat treatments. They were subjected to structural and micro-structural characterization processes to confirm their phase purity, crystal structure, surface morphology and elemental composition. The magneto-transport properties were explored and measurements indicated significant weak antilocalization (WAL) and non-saturating MR. The overall magnetoconductivity (MC) was analysed by modified Hikami-Larkin-Nagaoka (HLN) model by considering the effect of quantum, classical and bulk contributions.
The pristine Bi single crystals exhibited Shubnikov-de Haas (SdH) oscillations confirmed the presence of the Fermi surface and Berry’s phase. Interestingly, a huge MR (17000%) is also observed. Moreover, angle-dependent MR measurements were performed for Bi0.95Sb0.05 and Bi0.95Sb0.05, which confirmed the dominant contribution to the transport mechanism from 2D surface charge carriers. In the subsequent chapters, a similar study was also carried out for both Bi2Se3 and Bi2Te3 TIs single crystals.
To deeply understand the phenomena driving the transport mechanism in TIs, thin films with different thicknesses of 5 nm, 10 nm, 15 nm, and 20 nm, were deposited using the physical vapour deposition technique. The MC measurements suggests the dominance of SS in all the samples.
Lastly, the Type II DSM PdTe2 was investigated and HLN analysis of the magneto-transport measurements suggested the presence of TSS. The MR was linear and found to be non-saturating with an increase in the field. The Dirac point in these materials lies far below the Fermi level so the transport is dominated by non-relativistic carriers. Although, the MR was comparatively lower, the higher surface electron mobility may be beneficial for the development of future electronics
Comparative analysis of biochar carbon stability methods and implications for carbon credits
No full textBiochar is an emerging negative emission technology. Its ability to sequester carbon and subsequent carbon credit valuation hinge on the stability of its carbon structure. The widely used indicators of carbon stability H:Corg and O:Corg provide conservative results as these are based on limited incubation experiments and associated modeling results. The results from these accepted methods and other derived methods have not been compared as indicators of carbon stability in a variety of biochar samples. Furthermore, the influence of contrasting feedstock and production techniques on biochar carbon stability is not well explored. Therefore, to address these challenges, a comprehensive stability analysis of 21 different biochar samples with contrasting feedstocks and pyrolysis techniques was conducted using a combination of instrumental methods and derived indicators of carbon stability. Methods such as biochar carbon half-life, thermo-stable fraction, oxidation resistance (R50), and carbon sequestration potential (CS) were used. Based on the initial carbon content of the biochar, simple pyrolysis techniques have similar potential for carbon credits as biochar produced from advanced pyrolysis techniques. Results indicate that the carbon stability of a biochar product is primarily a factor of feedstock type. We found that biochar carbon stability is not related to volatile matter or fixed carbon content for biochar produced using a simple pyrolysis technique and mixed feedstock. Biochars with H:Corg < 0.4 were deemed to have lower carbon stability when compared using different methods. No correlation was observed between the carbon stability of biochar using H:Corg and other methods, however, correlations were observed between half-life, O:Corg, fixed carbon, number of aromatic peaks in FTIR spectrum, R50, and CS. Therefore, it is recommended that data from additional incubation and modeling studies need to be considered to increase the confidence in carbon stability r
Australia’s Voice in the Indo-Pacific
No full textThis book lays out the argument for a full re-boot of a well-funded and independent Australian public broadcaster that operates transnationally to provide trustworthy journalism in the Indo-Pacific region. As the provider of trusted news and information it is argued that the Australian Broadcasting Corporation is ideally positioned to amplify local voices and promote peace and security. By emphasising the need in the Indo-Pacific for Australian-produced journalism that can be disseminated across radio, television, online, social media and digital channels, thiss chapter sets up the book as a coherent work that explores the changing media landscape, the strategic importance of the Indo-Pacific, and the rise of transnational broadcasting services from countries, such as The People’s Republic of China, which do not share the same public service broadcasting heritage. It also examines the interplay between public diplomacy, propaganda, and journalism in the digital era, as well as the impact of social and mobile media on journalism during times of disaster. The book highlights the importance of fact-checking, verification, and media literacy, and provides a case study to illustrate the concerns which have arisen in Solomon Islands. It concludes that increased funding and support is necessary for Australia to operate a trusted transnational broadcaster in the region to counter disinformation and strengthen public service media
Fact-Checking and Verification: The Changing Role of Professional Journalists
No full textThis chapter sets out to discuss the impact of fake news on Indo-Pacific communities. In the first section it notes that media literacy is a problem across much of the region. In the second section it discusses the scale of the problem using interviews with working journalists in the Indo-Pacific to capture how they are increasingly using verification techniques, before looking at moderation and training of citizens, to illustrate how reporting techniques are adapting during the twenty-first century. We argue that greater fact-checking and verification training of journalists in the Indo-Pacific is needed, and while we acknowledge that public education in media is vital, we demonstrate how professional journalists can play a part in the solution
Distribution via Shortwave, Satellites, and Social Media
No full textAccess to independent trusted journalism in the Indo-Pacific requires a range of reception methods that rely on radio waves, shortwave frequencies, satellites signals, or undersea Internet cables. Drawing from interviews with leading journalists and broadcast managers across the region, this chapter outlines the significance of some of the changes to transnational news distribution. Acknowledging that governments and private entities can use the technology to block or support news and information getting to populations, this chapter pay particular attention to the security concerns that have arisen as a result of increasing reliance on the Internet, social media, and smart phone capabilities to publish and distribute information and particular concerns around the ownership of newer low-earth satellite technology
The Rise of China’s International Broadcasting Services
No full textIn consideration of the advancement of Internet and digital technologies, this chapter delves into strategic approaches and historical developments in establishing and expanding international broadcasting service networks in the global arena, specific to the case of China. This chapter examines the apparent motivation of these moves and the implications for the rest of the world. With the focus on the English-language international offering provided by the four state-run Chinese media outlets, known as the “Big Four”, including Xinhua News Agency, Central China Television (renamed as China Global Television Network), China Radio International, and China Daily, the discussion explores the broader implications of the rise of international broadcasting services for the expansion of international relations, beliefs, and ideologies
Advancing Troponin Point-of-Care Testing through Silicon Photonic Biosensors: Enhancing the Accuracy of Heart Attack Diagnosis
No full textThe adoption of cardiac troponin point-of-care testing in clinical settings remains challenging despite the rapid advancement of biosensing technology in the last decades. Point-of-care testing provides a faster troponin result at a fraction of the time, but its accuracy must correlate well with laboratory testing. The major drawback of point-of-care testing stems from its lower diagnostic sensitivity compared to central laboratory-based assays, such as benchtop chemiluminescent analyser, which can detect multiple cardiac biomarkers at a higher level of sensitivity within a single assay. However, this standard testing has its flaws. Even with the generation of the so called ‘high-sensitivity’ troponin assays, these benchmark assays still show discordant in the diagnoses of myocardial injury with different troponin I or T assays as shown by various comparative clinical studies published in the last 20 years.
Since early 1990s, the measurement of cardiac troponin assay has been based on the specific detection of either cardiac troponin I or troponin T subunit proteins, which are released into the bloodstream during myocardial infarction. However, these commercial troponin assays do not capture the complete extent of the infarction, as cardiac troponin is a complexed protein that metabolises into different isomeric forms of troponin molecules. The chosen antibodies, usually in pair for capturing and detection purposes, only detect selected few isomer forms, resulting in serious underestimation of cardiac troponin in patient samples and increases the potential for misdiagnosis. Recent studies published by Katrukha et al emphasised the differences of troponin composition in blood over time following acute myocardial infarction. These findings highlight the importance of using multiple antibodies to capture different isomeric forms of troponin for a more comprehensive diagnosis of the severity and extent of myocardiac injury.
To that end, in order to achieve a highly sensitive and accurate point-of-care testing that can rival the laboratory benchmark, it is first necessary to develop an assay that has the capability of discerning and quantifying troponin isomers in the blood. These studies provide insight and motivation for this doctoral thesis to detect the various troponin isomers during acute myocardial infarction progression to enhance the accuracy of troponin point-of-care testing. Ultimately, the next generation of troponin assays should provide clinical profiling of patients with acute myocardial infarction based on the composition of troponin in blood. This would enable clinicians to identify early to late acute myocardial infarction patients, potentially impacting timely treatment for these patients.
Photonic biosensors offer high sensitivity, multiplexing and label-free sensing capabilities, making them an emerging field with significant potential for advancing point-of-care diagnostics. First, they require no additional labelling that complicates the detection process. This increases the speed of analysis and lowers the overall cost, both of which are important for point-of-care diagnostic testing. Second, they can be easily integrated into a compact platform which is crucial for medical testing in emergency situations especially in remote areas. Medical professionals require access to devices that are easy to use and quick to deliver result to save lives. Third, photonic biosensors have the capability to be multiplexed, allowing the testing of all isomeric forms of troponin simultaneously, which increases the overall assay specificity. In future, this can be extended into the addition of other cardiac biomarkers to further enhance the specificity. Lastly, they can achieve high sensitivities, with some studies reporting detection limits in the attomolar to femtomolar range which can ensure troponin to be detected even in samples with ultra-low concentration.
Initially, a commercial surface plasmon resonance biosensor was utilised with a two-step approach to detect all troponin I forms. While the approach could differentiate between these isomers, it fell short of fully quantifying them. The insights gained, including the limitations found with surface plasmon resonance, led to the consideration of silicon photonic biosensor as a more suitable platform. An integrated Mach-Zehnder-based silicon photonic biosensor, coupled with an automated microfluidic system, was then employed, enabling precise sample manipulation necessary for biosensing. The performance of this biosensor was analysed in terms of sensitivity, reproducibility, and selectivity for troponin complex. The biosensor exhibited selective troponin detection within 10 minutes, operating across the ng/mL-µg/mL range with high reproducibility, and achieving a low limit of detection of 3 ng/mL, highlighting its potential for rapid and precise troponin detection. Nevertheless, further enhancements in sensitivity, reproducibility and selectivity were imperative to advance this system towards clinical point-of-care applications. A one-step silicon surface functionalisation using Silane-PEG molecules, based on the research of Cosa et al research on functionalising glass surfaces for fluorescence studies, was then introduced. This method was carefully adapted and optimised to be applied on silicon surfaces, with the purpose of creating a uniform monolayer of antibodies across the sensor surface and generating reproducible biosensors for cardiac troponin detection. This surface chemistry method was tested on the silicon photonic biosensor and the biosensor response was compared to the previous physiosorbed method. Despite the inherent limitations of this new approach, a significant improvement of at least 76% was observed in the biosensor response. The findings of this thesis demonstrated the capability of integrated silicon photonic biosensors for troponin detection. Further refinement of surface functionalisation and testing of the two-step methodology are necessary to enable the technology’s use with blood samples. The ultimate objective is to advance this technology for clinical readiness, with the goal of developing a point-of-care device that can improve patient outcomes and alleviate long-term burdens on the healthcare system.</p
Optical Clocks in GNSS Positioning
No full textAtomic clocks are highly precise timing devices crucial for Positioning, Navigation, and Timing (PNT) applications both on Earth and in space. In recent years, advancements in technology have led to the introduction of more precise timing solutions based on optical technology. State-of-the-art optical clocks, considered the next evolution of traditional atomic clocks, have achieved an unprecedented uncertainty of 1 × 10−18, surpassing the best atomic clock performance by two orders of magnitude. This breakthrough has garnered significant attention from academia and industry, opening up new opportunities for exploitation.
Despite this progress, limited research has been conducted to assess the impact of optical clocks on Global Navigation Satellite System (GNSS) precise positioning applications. Consequently, it remains uncertain whether more precise clocks would improve positioning solutions, from the perspectives of both GNSS community and clock manufacturers. Most research efforts have been directed towards clock development, further advancements, fundamental physics tests, gravity field determination, time and frequency transfer experiments, and metrology applications, with limited focus on evaluating the practical implications of optical clocks for GNSS positioning.
To address this gap, this thesis aims to investigate the advancements in optical clocks in comparison to atomic clocks and their potential to enhance GNSS positioning applications. The study addresses three primary research questions: exploring the development, characteristics, and significance of optical clocks in PNT; comparing their frequency stability with current GNSS satellites; and evaluating their impact on GNSS positioning performance.
To answer the research questions, the research conducts two key assessments along with an overview of optical clock development in existing literature. The first assessment involves a comprehensive analysis of clock stability, comparing the frequency stability of three state-of-the-art optical clocks with existing atomic clocks onboard GNSS satellites as of 2022. Using Allan Deviation (ADEV) metrics, this comparison reveals that optical clocks exhibit superior stability, indicating potential improvements in satellite-based positioning systems. Furthermore, the literature highlights challenges in optical clock maturity, including Size, Weight, and Power consumption (SWaP) parameters for practical deployments, and suggests future research directions to address these challenges.
The second assessment evaluates the impact of optical clocks on GNSS user positioning precision and the success rate in resolving carrier-phase ambiguities through a simulated GNSS Precise Point Positioning – Real Time Kinematic (PPP-RTK) application in MATLAB. The simulation assumes deployment of the three aforementioned optical clocks on GNSS satellites as the primary source of oscillation. Each clock undergoes an identical simulation scenario to isolate its impact from other error sources. The corresponding ADEV values driven by white noises are modelled as process noise in the Kalman Filter processing. The results demonstrate that optical clocks significantly enhance positioning precision and reliability, highlighting their potential to improve GNSS PPP-RTK applications.</p
Year End Project '(YEP)
No full textThe Year End Project is a locative art series that captures and visualizes the artist's daily movements over a year in 2015. Through the use of GPS technology, the project transforms everyday patterns of mobility into a digital art form, showcasing twelve GPS drawings—one for each month of the year. The evident geographic latitude longitude coordinated point on earth when elevated beyond its instrumental status can be understood as an existential proof – a beautiful evidence of one’s existence. The philosophy of existentialism has always been an influential undercurrent in art and human existential anxiety often becomes a recurring subject in art. Through arts artists question and express the meaning, purpose or value of existence. Subjective existence purported by Rene Descartes’s ‘I think, therefore I am’ has dominated our understanding of consciousness for nearly four centuries. However, in this digital era, the omnipresent GPS-based technologies and Internet connectivity in support of the constant communication of location is increasing the fluidity between physical world and virtual world. The result is a seamless experience that requires us to merge the body and mind as one. This extends the linear narratives of individual subject to include the possibility of multidimensional understanding of self and consciousness. This phenomenon presents to the artist an emerging potential to rethink the mind-body problems and the legacies of earlier existentialists’ approaches to mind, body and phenomenon. This series of GPS drawings (NTROs) presents an understanding of properties and attributes of presence and how it may be manifested through locative media.</p