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This thesis began with a question: How can we help children to learn? I examined this question by testing four distinct factors proposed to influence learning: number awareness, mindset, stereotyping and conscientiousness. Beginning with the effects of number awareness (Chapter 1), I focused on the approach of helping young children to understand the symbolic meaning of numbers. This idea was inspired by the study of Ramani and Siegler (2008) which tested whether playing a board game (e.g. snakes and ladders) in which their "player" was identified with a number would improve children's understanding of numbers and their numerical performance. I attempted to replicate this study in China but found no effect. Children who played the number board game did not show significant improvements in the post-manipulation numerical tests compared to children who played the coloured board game. I also noticed that children in my study showed a better baseline performance in counting and identification tests compared to children in the original study (in the U.S.). Therefore, I concluded that the board game manipulation was not helpful for raising number awareness among Chinese children. I then searched the literature for other manipulations that might help children on learning. The most prominent manipulation was based on mindset theory (Dweck, 2006), which measured whether children believe their intelligence is malleable or fixed (Chapter 2). Therefore, the second major theme, occupying most of the thesis, consisted of eight studies on mindset. In this vein, I firstly used both a mindset manipulation and a self-reported mindset scale to test whether having a growth mindset would improve children's cognitive performance after a challenge (Chapter 3). Children were firstly asked to solve a set of moderate difficulty cognitive problems, and then they were given a mindset manipulation: the experimenter either praised children for being smart (fixed mindset manipulation) or for working hard (growth mindset manipulation) on these problems (Mueller & Dweck, 1998). Following the mindset manipulation, the children were asked to work on a set of even more difficult problems (failure), and they were given negative feedback on their performance. This was followed by a final set of problems with moderate difficulty. I failed to find a consistent association between the growth mindset manipulation and improvement in children' postchallenge performance. The only nominally significant effect of growth mindset manipulation was found in my first study, but disappeared in the other two studies. I next tested whether children's own mindsets would be associated with their postfailure performance or school grades. Again, I failed to find a significant association between children's own mindsets and their post-failure performance or school grades. I then tested whether growth mindset would be associated with better grades only across a challenging transition or growth mindset would be beneficial only for children who encountered the greatest challenge when entering university (Chapter 4). Similar to my previous studies, I failed to find any significant effect of growth mindset on grades, either across a challenging transition (from high school to university), in any subsequent year in university, nor among children who encountered the greatest challenge when entering university. Finally, I explored whether children obtained their own mindsets from their parents' growth mindsets or parents' failure mindsets (Chapter 5). I found that children's own mindsets were significantly associated with their perceptions of parents' failure mindsets. However, these perceptions were biased by their own mind. Therefore, I concluded that mindset theory was not influential in the learning process, children might obtain their mindsets from their parents' failure mindsets, and children's perceptions of their parents' failure mindsets were biased. I also suggested that mindset manipulation has its limitations and suggested that rather than addressing mindset, addressing attitudes to hard work may be a viable direction. Next, I conducted a series of five studies to test a recent claim regarding the early origins of negative gender stereotypes about brilliance (Bian, Leslie, & Cimpian, 2017), that is proposed to reduce girls' interests in science-related subjects (Chapter 6). Consequently, the negative stereotypes would impair girls' academic performance and increase the gender gap in science-related subjects. I tested children' gender stereotypes about brilliance, kindness, and dullness, by presenting vignettes of people who were very high in these characteristics in both China and the U.K. (Chapter 7). I asked children to identify which person in two male and two female images presented to them was the person described in the vignette. The gender of the person chosen was used as an indicator of stereotyping. I failed to find the existence of a gender stereotype that brilliance was a male trait among Chinese children, but did find it among British children. For niceness, I did find that both Chinese and British children have a gender stereotype towards women. For dullness, both Chinese and British children hold a gender stereotype towards men. The final theme in this thesis was followed by the mindset theme, which consisted of four studies testing whether conscientiousness (i.e., attitudes towards hard work) would be associated with children' grades in both primary school and high school (Chapter 8). I found that conscientiousness was a significant and consistent predictor of grades in both primary school and high school. I also tested whether teachers' conscientiousness would be associated with children's grades. However, children's perceptions of their teachers' conscientiousness were not associated with children's grades. Thus, I concluded that conscientiousness was a powerful predictor of grades, but teachers' conscientiousness might not be. In the final chapter (Chapter 9) of this thesis, I concluded the main findings in the thesis, discussed the implications for each theory I explored, and made suggestions for further studies in the studied areas.

This thesis presents research at the intersection of Extended Reality (XR) and Cultural Heritage - Virtual Heritage (VH). Prior research in VH has used Virtual Reality (VR) for immersive visualisation and Augmented Reality (AR) has been used for enhancing exhibitions. These reality technologies were primarily configured for use within museums, which are limited in terms of physical touch and handling capabilities and remote accessibility. Recent advances in XR and its rapid growth and affordability across various consumer devices are providing new opportunities for cultural heritage to be accessed outside the walls of the museums. However, virtual exhibitions and physical visits are different in many ways. Challenges remain for XR in its ability to emulate physicality and materiality, and the social environments within which interpretation, knowledge and ideas are exchanged. Meanwhile, the diversity of devices that are adopted as a consequence of user preferences necessarily means that technologies developed for users should take into account such a need as audiences are central and core to the activities of cultural institutions. In view of such a need, XR presents many challenges that are unsolved, one aspect of which is related to the concept of Extended Reality itself in its broad spectrum between physical reality and virtual reality. As users adopt their preferred devices within the XR spectrum, it has become essential to investigate the intersection of such use if communication within the spectrum is to be made possible. In addressing the need and challenge, this research designed a Hybrid Virtual and Augmented Reality (HVAR) environment and evaluated what could work if users were to socialise between the spectrum of realities. This research presents two frameworks that conceptualise virtual objects and virtual exhibitions for the connections between the spectrum of realities. Three technological developments were made for experimenting with hybridity in terms of interaction, communication and engagement for users with different XR devices. The initial experimental study indicated that users prefer to have control of movement and object information over guided tours and automatically triggered information, providing insights into the interaction design in virtual exhibitions. Follow up studies found that user acceptance of HVAR is strongly affected by social influences, and their communication within HVAR can be explained through the understanding of perceived presence. Building upon these, this research further investigated factors influencing user engagement within HVAR with an innovated objective measure of engagement using a wearable electroencephalogram (EEG) device combined with user activity monitoring at system runtime, suggesting the effects of object interactivity, User-Generated Content (UGC) and avatar proximity on user engagement. This research innovates the use of Hybrid Virtual and Augmented Reality environments. It has implications for the future design, evaluation and application of XR in various domains that necessitates sociality.

The thesis is on coinduction in Horn clauses. Specifically, it considers productive corecursion, and presents a framework called Coinductive Uniform Proof as a principled approach to coinduction in first-order Horn clause logic. It addresses the challenges of 1) discovering sufficient conditions for logic programs to be productive, 2) providing an explanation of why unification (without occur-check) between goals in a SLD derivation can be exploited to capture productive corecursion, and 3) identifying the principle that unifies the diverse approaches to Horn clause coinduction which are scattered across the literature. The thesis advances the state of the art by 1) providing a sufficient condition for productive corecursion which requires that a logic program does not admit perpetual term-rewriting steps nor existential variables, 2) showing that the goal-unification technique can be used to capture productive corecursion if a goal is no less general than some previous goal to which it unifies, and 3) defining a coinductively sound proof construction method for Horn clauses where a Horn clause to be proved is first asserted as an assumption and then used for its own proof.

Artificial spin ice (ASI) is a class of magnetic patterned arrays consisting of interacting ferromagnetic nanomagnets. The nano-scale size and the elongated shape of each nanomagnet ensure the formation of a single domain, which behaves as a ‘macrospin’ and results in only two possible magnetisation directions along the long axis of the nanomagnet. ASI system has the potential ability not only as a magnonic crystal because of the microwave properties being associated with its intrinsically intricate magnetisation topologies and inter-element interaction, but as a tool to model the microstructure of atomic scale allowing its fundamental physics to be studied. This thesis addresses the field-induced properties of the static and dynamic magnetisation in square and pinwheel ASI. Firstly, the magnetic properties of the square ASI specimens were characterised using alternating gradient force magnetometry, Brillouin light scattering and ferromagnetic resonance. Micromagnetic simulations were employed to assist in understanding the experimental results. Secondly, the field-induced evolution of the magnetisation configuration in a finite-size pinwheel ASI array was imaged using Lorentz transmission electron microscopy. The square structure of the square ASI lattices allows a comparison of the response of the spin-wave modes in the two groups of magnetic elements which are orthogonally aligned to one another. The frequency of the spin-wave mode is dependent on the direction of the applied field, either along the easy or hard axes of the nanomagnet. It has been found that more spin-wave modes are found when the magnetic field lies along the hard axis of the nanomagnet compared to when the field is aligned with the easy axis of the island. This attributes to the formation of more edge modes of standing spin waves in the former case. The experimental behaviour of the static and dynamic magnetisation can be well described via the micromagnetic simulations where only an individual island is considered with an assumption that the inter-island interaction is negligible. Additionally, the field direction with respect to the square ASI lattices is also responsible for the changes in spin-wave frequencies. The results imply that the square ASI could act as a reconfigurable microwave resonator due to its spin-wave frequency being dependent on the changes in magnetisation configuration that were controlled by the applied field. The dependence of the nanomagnet thickness on the static and the dynamic properties of the square ASI was studied. The nanomagnet thickness is found to be responsible for the coercivity and the number of observed spin-wave modes of the square ASI array. The thicker ASI array has a larger coercive field and produces more spin-wave modes. Micromagnetic simulations suggest that the inter-island coupling contributes weakly to the coercivity and the spin-wave frequency of the thicker array whereas it is negligible for a thinner array. Furthermore, fitting to ferromagnetic resonance data allows for access to information on ferromagnetic parameters, such as gyromagnetic ratio and saturation magnetisation. Finally, static and dynamic magnetisation topologies in a pinwheel ASI is explored as a function of magnetic field. The pinwheel ASI is a square ASI modified by rotating each nanomagnet 45° around its central axis in the same direction. The energy spread between the pinwheel vertices significantly decreased as the geometrical structure transforms from the square vertices to the pinwheel vertices. The ferromagnetic magnetisation process shows the domain growth mediated via the propagation of domain walls. Intriguingly, some of the observed mesoscopic domain-wall topologies resemble the Néel and the crosstie walls seen in natural ferromagnetic films, while others mimic the configurations of the charged walls found in the ferroelectric materials. In addition, a rotational-field demagnetisation was carried out in order to anneal the pinwheel ASI to the ground state. The results show that the net moment of the entire array decreases and the short-range ground state is attained through the presence of the vortices (Type III) and antivortices (Type IV) vertices, rather than the global Landau-like flux closure structure predicted by Monte Carlo simulations.

The background to this study is an effort to exploit a magneto-inductive waveguide (MIW) for near-field contactless data and power transfer applications. MIWs are almost purely magnetically coupled metamaterial waveguides whose coupling strengths can never exceed the limit of conservation of magnetic flux. This study raises the hypothesis that the coupling strength limit of MIWs can be overcome by incorporating additional electric coupling into the structures; therefore, more strongly coupled metamaterial waveguides can be built and serve as contactless near-field communication channels with wider passbands and lower attenuations. The hypothesis was tested in this study by investigating a new variant of the metamaterial waveguide: the Capacitor-Connected Grid (CCG), in which additional electric coupling is introduced by connecting coupling capacitors over inter-element gaps between conventional MIW metallic loop resonators. The study investigates the dispersion and attenuation characteristics of both one- (1-D) and two-dimensional (2-D) CCG devices, leading to a discussion on their potential uses in ultra- wideband (UWB) contactless near-field data transfer applications. A mixed coupling model calculating inter-element mixed coupling coefficients for arbitrarily configured CCG waveguides is derived based on the state-of-the-art, taking into account the shift of resonant frequency caused by electric coupling. The study also looks at terminal optimizations for 1-D CCG with a view to maximizing power transfer efficiency. A highlight of this study is that a 1-D CCG demonstration device in theory should be able to achieve 192.4% fractional bandwidth, which exceeds the 20% requirement of a UWB channel by a factor of 9.6, and is only 1/10 of the minimum attenuation of an equivalent-sized MIW device. Similar communication characteristics have also been found at selected transmission paths on a 2-D CCG demonstration structure. The results of this study on CCG waveguides verify the hypothesis that incorporating additional electric coupling into an almost purely magnetically coupled waveguide can improve its coupling strength and thereby achieve a communication channel with larger bandwidths and lower losses.

This study is a qualitative analysis of direct cultural encounters between China and the West. It examines the subjective experiences of Chinese students in Britain and Western expatriate teachers in China from their own viewpoints – how they understood and interpreted different cultures and made sense of similarities and differences between one another, that is, how they experienced cultural translation. It employs focus group and individual interviewing methods. This study adopts an analytical framework of a before-during-after logic to answer three questions: 1) why did participants come to the host country and what did they think of it before arrival? 2) how did they relate to the host environment and make sense of differences? and 3) how these direct cross-cultural experiences influenced them as well as the wider context of cultural relations between China and the West? It presents the historical background of cultural and educational exchange between China and the West and identifies motives of participants coming to the host country under the current context of global cultural flows. Furthermore, it highlights factors that differentiated the subjective experiences of participants, such as gender, duration of time spent in the host country, relationships with local people and the subjects of study. The effects of participants’ experiences in the host country also varied according to these factors. What underpins the relationship between China and the West in terms of cultural and educational contacts, presented by Chinese students in Britain and Western expatriate teachers in China, is fundamentally an interplay between economic and cultural factors. Differences between China and the West are as much cultural as institutional. This study provides a detailed account of such differences. It discusses what aspects of Western cultural values have a strong influence on China and which traditional Chinese values still hold their importance during direct cultural encounters with the West. It reveals the internal struggle, caused by cultural differences and institutional limitations, amongst both Chinese students in Britain and Western expatriate teachers in China, but it also highlights the ways in which some differences have been exaggerated during direct cross-cultural encounters as well as the profound social and cultural similarities shared by China and the West, which tend to be overlooked.

Due to the fast growth of digital technology, daily activities can be easily captured and saved in digital images, and then transmitted via the Internet. Therefore, the huge amount of digital images need to be protected through authentication techniques. This thesis is concerned with digital image authentication (DIA) techniques used for anti-falsification, copyright protection and access control. DIA techniques can be generally categorised into data-hiding-based digital image authentication (DHBDIA) techniques and non-data-hiding-based digital image authentication (NDHBDIA) techniques, which are both studied in this thesis. DHBDIA techniques, which are also called watermarking schemes, realise image authentication by imperceptibly embedding a piece of authentication information into images. In this thesis, three watermarking schemes are proposed to serve different purposes. To improve the performance of current clustering-based watermarking schemes, an expandable progressive exponential clustering (EPEC)-based watermarking scheme is proposed, which embeds secret data in the host image by progressively and exponentially clustering the colour intensities in the spatial domain, expanding the cluster table under predetermined constraints and substituting the intensities in the same clusters. This scheme strikes a better balance between embedding capacity and embedding distortion than traditional clustering-based watermarking schemes. To enhance the security of current quantisation-based watermarking schemes, an adaptive quantisation index modulation (AQIM)-based watermarking scheme is proposed, which adaptively modifies the quantised values in the embedding phase, consequently preserving the histogram of the image and closes the security gap. For the image authentication, a repetitive index modulation (RIM)-based watermarking scheme is proposed to set up a non-deterministic dependence among pixels. This scheme achieves higher security and lower distortion than traditional LSB-based watermarking schemes. Meanwhile, to study the applicability of DHBDIA techniques, a multifunction digital image authentication system for medical image management on PACSs is proposed to perform three different security assurance functions, namely role-based access control, patient’s medical information integration with mammograms and forgery detection. In the study of the NDHBDIA techniques, a colour-decoupled photo response non-uniformity (CD-PRNU) is devised to serve as a camera fingerprint for both source camera identification and content integrity verification. In the image acquisition process, colour filtering and interpolation are two important operations that introduce large amounts of noise, which are not included in the traditional PRNU definition. The proposed CD-PRNU extends the traditional photo response non-uniformity (PRNU) extraction model by including such types of noise. As a result, the CD-PRNU is more accurate and effective in camera identification and content integrity verification. The main feature of the proposed CD-PRNU extraction algorithm is that it can separate physical colour components and artificial colour components without the prior knowledge about the Colour Filter Array (CFA) and then extract the PRNU from each individual colour channel, thus preventing interpolation noise of artificial components from diffusing into the sensor pattern noise of the physical colour components.

This interpretive case study explored the effectiveness of listening strategy instruction that promoted self-regulated learning and gained insights into students' and instructors' perceptions of strategy-integrated listening instruction among second semester learners of Chinese as a second language at a military college in Northern California. Most of previous studies investigated listening strategy use and the relationship between listening strategy use and listening achievement. Few studies investigated the effectiveness of listening strategy instruction. Thus, this study addressed the gaps in research by examining the effectiveness of integrating listening strategies into regular curriculum and explored students' and instructors' perceptions of listening strategy instruction among learners of Chinese as a second language. An interpretive case study research design was employed to achieve the goal of this study. The participants included one instructor and six students who studied at an intensive Chinese basic course. Three sources of data were collected from 25 classroom observations, a focus group session with the student participants, and a face-to-face interview with the instructor. All data were transcribed, coded, and analyzed to answer the research questions. The findings of this study showed that some of cognitive, metacognitive, and motivational strategies were identified as effective in promoting self-regulated learning among learners of Chinese as a second language. The findings also supported that listening strategy instruction helped learners raise awareness of strategy use, increase self-confidence, improve listening abilities, and foster learner autonomy and self-regulation. The findings further indicated that implementing strategy-integrated listening instruction could improve teaching quality, but might face possible challenges from teachers. Finally, the findings suggested that teacher training on integrating listening strategies into regular curriculum should be provided. This study has implications for language teachers, foreign language learners, and language course developers, who are involved in the field of foreign language teaching and learning. More research on self-regulated learning and listening strategy instruction among learners of Chinese as a second/foreign language would further expand the understanding of listening strategy instruction in the field and better assist language learners to succeed in their learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]

The present study is an empirical investigation into repair in spoken discourse, specifically focusing on L2 learner conversation, group work and teacher-fronted classroom interaction. The core of the investigation concentrates on identification of the problem type, classification of repair strategies and examination of interaction in the repair process. A comparison between Conversation (CS), Group Work (GW), and Teacher-fronted classroom interaction (CR) suggests that more repair is undertaken in CS. The results of the study suggest that the fundamental differences between CS, GW and CR are of two types: in the frequency of repair and in the nature of the repair itself. It has been found that other-initiation for production problem repair occurs mainly in CR, other-completion is characteristic of GW and self-repair is most frequent in CS. Factors affecting the occurrence of repair in CS, GW and CR are related to content and social and communicative features of context. Importantly, the study shows the frequency of repair in GW falls between that of CS and CR in most of repair strategies. This result lends support to the argument that group work can assist L2 learners to develop their communicative competence. It is suggested that the analysis of the repair process in CS, GW and CR can be useful in throwing light on the intricacies of spoken discourse in general and can be exploited by applied linguists for both theoretical and pedagogical purposes.

This dissertation consists of three essays on empirical financial economics. The first essay, “External Litigation Risk and Corporate ES Performance: Evidence from Federal Judge Ideology”, explores how firms’ environmental and social (ES) performance are affected by external ES litigation risk, proxied by judge political ideology. The second essay, “Local Environmental Beliefs and Corporate Environmental Performance”, which was co-authored with Yuhai Xuan and Hong Wu, investigates the effect of local environmental beliefs on US establishments’ environmental performance and on firms’ pollution reallocation decisions. The third essay, “Information on Collateral Value and Bank Mortgage Lending”, studies the US residential property market and the effect of collateral information advantages on banks’ lending decisions.

5G and Simultaneous Transmit and Receive (STAR) at radio frequency have led to an ever-increasing demand for physically smaller, wider bandwidth communication devices. In addition to civilian demand, electronic warfare also calls for robust RF systems that provide high fidelity communication and sensing in the presence of numerous interferences. Ultra-wideband Integrated Phased Array Systems are a major part of the solution to all this growing demand. Two components of particular interest to building an Ultra-wideband Integrated Phased Array System have been constructed with Gallium Nitride (GaN) transistors. The constructed circulator and power amplifier (PA) components both have excellent broadband, small-form factor, and scalability properties.Using a switching network of transistors and transmission lines, it is possible to replicate the behavior of a traditional circulator. This constructed device, the Sequentially Switched Delay Line (SSDL), can overcome a circulator’s conventional limitations in insertion loss, form factor and bandwidth. Using passive bootstrapping, it is possible to increase the power handling and lower the insertion loss. Arranging SSDL devices in an array, it is possible to further raise the power handing and reduce distortions from the transistors’ higher order intermodulation terms. The SSDL in a 3,4,..,N-port setting, can provide a non-reciprocal device for simultaneous transmit and receive at the same radio frequency. The SSDL can also be used as a gyrator in a 2-port setting; it can provide a wideband conversion of a capacitor into an inductor.A new differential broadband GaN PA design for direct integration with a Tightly Coupled Dipole Array (TCDA) will also be discussed. Using differential amplifiers, the overall PA design can be made balun-less. Using direct integration to a TCDA load, the overall PA design can leverage the TCDA’s common mode rejection of the second harmonic. Combining these design principles, the new integrated PA is also able to overcome conventional limitations in form factor and bandwidth.

Understanding how messages go viral and become distorted during the transmission process lays the foundation for enhancing surveillance, understanding the psychological drivers of information transmission, evaluating the real-world impact of misinformation, and developing effective responses. The two studies of my dissertation contribute to this field by identifying distinct patterns of virality and fidelity during the transmission of information with varying degrees of veracity. Furthermore, this dissertation investigates potential factors that are associated with the virality and fidelity of information transmission – network attributes, message features or entities, and the interactions between them. Study 1 focuses on the virality of information transmission. Specifically, this study collected tweets and corresponding retweets about COVID-19 vaccines in the first week of December 2021. Guided by diffusion of innovations theory, I scaled-up theory-driven content analysis of the tweets’ message features with deep neural network language models, and employed social network analysis to measure the follower networks’ clustering and the diffusion networks’ virality. The results of the multilevel models show that high-truthfulness tweets are more likely to go viral than low-truthfulness tweets. Clustering not only serves as a positive predictor of virality across tweets with low and high truthfulness, but also moderates how threat-based information affects information virality. For high-truthfulness tweets, threats of the pandemic fuel information virality in a non-clustered network, whereas threats of vaccines enhance virality in a more clustered network. Different types of efficacy information do not significantly predict virality in all tweets, irrespective of their truthfulness levels.Study 2 focuses on the fidelity of information transmission. Specifically, this study collected tweets and corresponding quote tweets about COVID-19 vaccines in December 2021. I coded ten categories of named entities within each tweet, which then served as the training data for the named entity recognition task. Guided by fuzzy trace theory, all named entities were classified into gist-based entities (e.g., key points) and verbatim-based entities (e.g., details). The results of the multilevel models indicate that gist-based entities maintain significantly higher fidelity than verbatim-based entities, suggesting that gist-based information and verbatim-based information are processed separately in the brain. Despite the relatively lower fidelity of verbatim-based entities compared to gist-based ones, tweets with low truthfulness tend to preserve high fidelity of verbatim-based entities more so than tweets with high truthfulness. In contrast, high-truthfulness tweets tend to maintain high fidelity of gist-based entities, such as side effects of vaccines. Moreover, certain verbatim-based entities (i.e., organizations and experts) conveyed by opinion leaders are significantly more likely to maintain high fidelity compared to those from non-opinion leaders. Threat-based entities (i.e., side effects of vaccines) from widely shared messages tend to maintain high fidelity compared to those from less frequently shared messages.The theoretical, methodological, and practical implications of both studies are also discussed in detail.

Decentralized applications (dApps), enabled by the blockchain and smart contract technology, are known for allowing distrustful parties to execute business logic without relying on a central authority. Compared to regular applications, dApps offer a wide range of benefits, including security by design, trustless transactions, and resistance to censorship. However, dApps need to access real-world data to achieve their full potential, relying on the data oracles. Oracles act as bridges between blockchains and the outside world, providing essential data to the smart contracts that power dApps. A significant challenge in integrating oracles into the dApp ecosystem is the Oracle Problem, which arises from the difficulty of securely and reliably providing off-chain data to smart contracts. Trust issues, centralization risks, and data manipulation are some concerns of the Oracle Problem. Addressing these challenges is vital for the continued growth and success of dApps. In this paper, we propose DEXO, a novel decentralized oracle mechanism designed to tackle the oracle problem by leveraging the power of Trusted Execution Environments (TEEs) and secure attestation mechanisms. DEXO aims to provide a more transparent, decentralized, and trustworthy solution for incorporating external data into dApps, ensuring that the data originates from regular, trustworthy dApp users. By empowering dApp users and developers to contribute diverse data types, DEXO fosters a more dynamic and enriched ecosystem. The proposed DEXO network not only addresses the challenges posed by the Oracle Problem but also encourages greater trust and confidence in the data provided to dApps, ultimately enhancing the overall user experience and promoting further growth in the decentralized application space.

This thesis is concerned with the challenge of deriving disparity from sparsely communicated depth for performing disparity-compensated view synthesis for compression and rendering of multiview images. The modeling of depth is essential for deducing disparity at view locations where depth is not available and is also critical for visibility reasoning and occlusion handling. This thesis first explores disparity derivation methods and disparity-compensated view synthesis approaches. Investigations reveal the merits of adopting a piece-wise continuous mesh description of depth for deriving disparity at target view locations to enable disparity-compensated backward warping of texture. Visibility information can be reasoned due to the correspondence relationship between views that a mesh model provides, while the connectivity of a mesh model assists in resolving depth occlusion. The recent JPEG 2000 Part-17 extension defines tools for scalable coding of discontinuous media using breakpoint-dependent DWT, where breakpoints describe discontinuity boundary geometry. This thesis proposes a method to efficiently reconstruct depth coded using JPEG 2000 Part-17 as a piece-wise continuous mesh, where discontinuities are driven by the encoded breakpoints. Results show that the proposed mesh can accurately represent decoded depth while its complexity scales along with decoded depth quality. The piece-wise continuous mesh model anchored at a single viewpoint or base-view can be augmented to form a multi-layered structure where the underlying layers carry depth information of regions that are occluded at the base-view. Such a consolidated mesh representation is termed a base-mesh model and can be projected to many viewpoints, to deduce complete disparity fields between any pair of views that are inherently consistent. Experimental results demonstrate the superior performance of the base-mesh model in multiview synthesis and compression compared to other state-of-the-art methods, including the JPEG Pleno light field codec. The proposed base-mesh model departs greatly from conventional pixel-wise or block-wise depth models and their forward depth mapping for deriving disparity ingrained in existing multiview processing systems. When performing disparity-compensated view synthesis, there can be regions for which reference texture is unavailable, and inpainting is required. A new depth-guided texture inpainting algorithm is proposed to restore occluded texture in regions where depth information is either available or can be inferred using the base-mesh model.

The Maritime Continent is a region with profound climatic importance on both local and global scales. However, correctly simulating the climate of the Maritime Continent and its interaction with other climate phenomena remains a great challenge for the modelling community. In this thesis, a range of simulations from a new atmosphere-ocean coupled regional model have been carried out to evaluate the model’s ability to represent the mean state and variability of precipitation. Given the existence of strong surface temperature gradients and the possibility of intense air-sea interactions in this region, targeted numerical simulations are further undertaken to test if air-sea interaction at different spatio-temporal scales can improve the simulation of precipitation from sub-daily to seasonal timescales. In particular, three factors are examined: 1) the coupled model’s horizontal resolution; 2) the coupled model’s coupling frequency and 3) the resolution of SST forcing in an atmosphere only configuration. An evaluation of the model showed dry biases in mean precipitation that decreased with resolution. However, although the diurnal evolution of across-shore propagation of winds and rainfall improved with resolution, increasing resolution led to little overall improvement in the timing of the diurnal cycle. We found that differences in the processes affecting the coastal diurnal cycle were strongly modulated by the direction of the prevailing winds relative to the coastline. Coupling frequency sensitivity experiments showed that mean and diurnal precipitation were only affected by sub-daily coupling in localised regions where air-sea interaction is known to be strong. In particular, precipitation changes off western Sumatra were tied to two interacting processes: a wind-thermocline-SST and precipitation-barrier layer-SST feedbacks. Finally even with large increases in SST resolution that resolve small scale ocean features, little discernible effect was found on either the long-term mean or spatio-temporal variability of precipitation and has only a small influence on daily timescale precipitation over the Maritime Continent. The thesis suggested that high frequency air-sea coupling frequency might provide significant added value for regional models, but only in certain areas where air-sea coupling is already important. However, the added cost of increased ocean resolution may result in limited improvements for high-resolution atmospheric simulations.

This quantitative study examined 1) the gender gaps in science, technology, engineering, and mathematics (STEM) faculty retention rates at two large, Midwestern, Research One universities; 2) the gender differences in STEM faculty’s perceptions of organizational and personal/professional factors, related to their retention outcomes; and 3) how faculty perceptions of organizational and personal/professional factors contributed to their actual retention at these two universities and what gender differences existed in modeling STEM faculty retention. Major findings included that 1) women STEM faculty, especially those hired initially as assistant professors, left the university at higher rates and stayed at the university for a shorter amount of time, compared to male faculty at the same rank; 2) male STEM faculty who departed held the least positive perceptions of their work life, male faculty who stayed had the most positive perceptions, while retained female held slightly less, negative views, than did departed males and females on most factors; 3) departed men and women faculty reported more positive perceptions of their self-efficacy and willingness to pursue leadership than did faculty who were retained; 4) retained female faculty held the most positive perceptions of departmental support for work-family balance among the four groups; 5) satisfaction served as a mediator between perceptions of organizational and personal/professional factors and retention outcomes for both female and male faculty; 6) a higher level of departmental support for work-family issues, less workplace incivility, and more positive attitudes about the university contributed to higher satisfaction, which in turn contributed to a greater likelihood of being retained at their universities for all faculty; 7) self-efficacy and willingness to pursue leadership had a significantly negative direct effect on retention for all faculty and for male faculty, but not for female faculty; 8) clarity and objectivity of departmental policies, respect, openness/transparency, and belief in university’s commitment to diversity had a significant effect on satisfaction for all faculty and for male, but not for female faculty; and 9) intersectionality among gender, race/ethnicity, and academic rank influenced certain aspects of faculty perceptions and retention outcomes. Policy implications included that university administrators should identify a specific set of leverage points to make policy and practice changes that are most likely to improve faculty retention outcomes. Institutional and departmental support for work-family balance should be implemented for all faculty across their life course. Institutions should provide local leadership opportunities to faculty in order to retain them at their institutions.

Professional development programs create communities of practice for environmental educators to exchange ideas and practice with each other through face-to-face and online activities. It is particularly important to understand how educators form networks through such communities, and how these networks impact their environmental education practice. Using multiple conceptual lenses -- including communities of practice, network formation, practice theory, professional development, and environmental education -- I examined the relationship between professional networks and practice change in environmental education. The professional development programs that are the focus of this study, including a state consortium that brought together environmental education and youth development professionals, an online learning community that explored urban environmental education, and a fellowship program focused on climate change education, are part of the North American environmental education professional development training program, EECapacity. First, I explore environmental educators’ communities of practice from a social network perspective by addressing the question: What were the characteristics of networks and the processes by which professional networks emerged in three environmental education professional development communities? I conducted surveys and social network analysis to examine educators’ networks before and after the professional development programs. The results showed that educators had more network ties among each other after the programs than before the programs across all three groups. Also participating in face-to-face meetings and online interactions increased the likelihood of educators’ forming professional networks. Next, I applied practice theory to explore the research question: How did environmental educators change their practice through participating in professional development communities? I conducted surveys and interviews to investigate educators’ practice change as measured by elements of practice including goals, audiences, settings, activities, resources and ideas. The results showed that environmental educators incorporated new resources and ideas into their practice across all three programs. However, changes in the other practice elements varied among programs, which I attribute to different program goals and professional development interventions. To explore the relationship between network properties, including in-degree, out-degree, closeness and betweenness centrality and tie strength, and practice change, I conducted correlation analysis. The results showed that in-degree centrality had a positive relationship with practice change in the state consortium and the online learning community, and other network measures only showed significant relationships with practice change in the state consortium. Finally, to better understand the process of change in networks and practice, I also conducted interviews in the state consortium and online learning community, and analyzed educators’ mid-term and final reports in the fellowship program, which showed how the fellowship program and networking opportunities impacted their practices. This dissertation explores dimensions of the communities of practice framework from social network and practice theory perspectives. It advances our understanding of the mechanisms of network formation, practice change, and the relationship between networks and practice change in environmental education. I also propose applications for professional development programs and recommendations for future research.

Abstract: Neurological disorders are among major causes of disability in Canada. In the diagnostic procedure, Magnetic Resonance Imaging (MRI) is commonly used as it is non-invasive and can produce dramatic contrast between different brain tissues. Brain tissue segmentation is a fundamental step in brain MR images analysis. Corpus Callosum (CC) is an important brain tissue and is always adopted as the landmark of human brain. In this thesis, we propose an intelligent computer-aided detection (CAD) system for automatic segmentation of CC in T1-weighted midsagittal brain MRI slices. The proposed CAD system has three modules: Adaptive Mean Shift Clustering (AMS), Automated CC Contour Initialization (ACI), and Geometric Active Contour (GAC) based Segmentation. In the first module, homogenous regions in the input image are divided into clusters with an adaptive mean shift clustering method. In the second module, area analysis, template matching, shape and location analysis are used to identify the cluster that contains CC and extract a rough boundary of CC as the initial contour. In the last module, the boundary of recognized CC region is used as the initial contour in the GAC model, and is evolved to obtain the final segmentation result of CC. Experimental results demonstrate that the proposed AMS-ACI technique is able to provide accurate initial CC contour, and the proposed AMS-ACI-GAC technique overcomes the problem of user-guided initialization in existing GAC techniques, and provides a reliable and accurate performance in CC segmentation.

Java reflection is increasingly used in a range of software and framework architectures. It allows a software system to examine itself and make changes that affect its execution at run-time, but creates significant challenges to static analysis. This is because the usages of reflection are quite complicated in real-world Java programs, and their dynamic behaviors are mainly specified by string arguments, which are usually unknown statically. As a result, in almost all the static analysis tools, reflection is either ignored or handled partially, resulting in missed, important behaviors, i.e., unsound results. Improving or even achieving soundness in reflection analysis will provide significant benefits to many clients, such as bug detectors, security analyzers and program verifiers. This thesis first introduces what Java reflection is, and conducts an empirical study on how reflection is used in real-world Java applications. Many useful findings are concluded for guiding the designs of more effective reflection analysis methods and tools. Based on this study, this thesis then presents two new techniques for handling reflection statically: a self-inferencing analysis called Elf, and a soundness-guided analysis called Solar. Elf is able to analyze reflection more effectively than the previous string resolution approach by exploiting a self-inferencing property found in our study. Such property is inherent in almost every reflective call, but not fully exploited by existing methods. Elf could make a disciplined trade-off among soundness, precision and scalability, while also discovering usually more reflective targets than in the previous work. Solar allows its soundness to be reasoned about when some reasonable assumptions are met, and yields significantly improved under-approximations otherwise. In addition, Solar is able to accurately identify where reflection is analyzed unsoundly or imprecisely and it provides a mechanism to guide users to iteratively refine the analysis results by lightweight annotations until their specific requirements are satisfied. For both Elf and Solar, this thesis presents their methodologies and formalisms and evaluates them against the state-of-the-art solutions with a set of large Java benchmarks and applications. The experimental results demonstrate their effectiveness as the new state-of-the-art reflection analyses in practice. Both Elf and Solar have been made available as open-source tools.

This work investigates how the provision of a variety of public policies affects individual life-cycle decisions. In Chapter 2, I examine the effects of the Affordable Care Act (ACA) by considering a dynamic interaction between extending health insurance coverage and the demand for federal disability insurance. I argue that as the ACA provides insurance coverage to the uninsured, it improves this group's health and reduces their demand for federal disability insurance. In order to provide a quantitative assessment of this dynamic link, I extend the Bewley-Huggett-Aiyagari incomplete markets model by endogenizing health accumulation and disability decisions. Findings suggest that the ACA reduces the fraction of working-age people receiving disability benefits from 5.7 to 4.9 percent. Chapter 3 analyzes the effects of social security survivors benefits and argues that survival benefits provide insurance against the heterogeneity of mortality rates. Specifically, the provision of survivors benefits mitigates the inequality induced by within cohort mortality differences and the associated price variations in the private life insurance market. Further, survivors benefits also help insure the uncertainties of income shocks and life events. The risk spreading provided by survivors benefits, however, is funded via taxes that distort individual decisions. Counterfactual results from a dynamic model suggest that removing survivors benefits for dependent children and aged spouses generates an ex-ante utility change equivalent to a 0.3 percent decline and 0.8 percent increase of permanent consumption, respectively. In Chapter 4, considering that people choose both years of education and their area of specialization, I estimate the impacts of technological progress and immigration on educational choices of native-born Americans. Results derived from a general equilibrium model suggest that these two changes lead to opposite effects on educational choices. In particular, the influx of immigrants reduces natives' incentives to complete college degrees and major in natural sciences and engineering fields.

The Indian and Australian summer monsoon systems have considerable socioeconomic and environmental importance. Here we investigate monsoon seasonality, biennial variability and the interaction with Tropical sea surface temperatures (SST) in the Indo-Pacific sector. We consider a variety of observational and reanalysis products and also assess climate models from the Coupled Model Intercomparison Project Phase 3 and 5 (CMIP3 and CMIP5). In particular, the transitions between successive Indian and Australian monsoons, that form essential parts of the Tropospheric Biennial Oscillation (TBO) have been evaluated. We use Monte Carlo statistical techniques to examine the predictive skill that is inherent in these monsoon transitions and investigate the possible teleconnections between SST anomalies in the Indo-Pacific region, particularly associated with the El Niño-Southern Oscillation (ENSO). Most climate models reproduce enhanced rainfall in the correct seasons for both the Indian and Australian monsoons. However, there are a number of biases in wet season duration and rainfall strength. While little improvement is seen in the overall strength of the monsoon rainfall from CMIP3 to CMIP5, there is a clear improvement in the seasonality particularly in simulating low rainfall rates outside of the monsoon season. Enhanced predictability associated with the Indian-Australian monsoon in-phase transition is present in all observational and reanalysis datasets and most CMIP climate models, i.e. we have some skills in predicting whether an Australian monsoon will be stronger/weaker than normal, given information on the strength of preceding Indian monsoon. The SST anomalies in the Niño 3.4 region in December-March (DJFM) after the Indian monsoon season appear to be important for this transition. For the Indian-Indian monsoon out-of-phase transition, enhanced predictability only occurs in long-term observations but with little consistency across models. DJFM SST anomalies in the Niño 3.4 region over successive years appear to strongly affect this transition. The enhanced predictability for the other transitions shows little consistency between observational and reanalysis datasets, climate models and time periods. Multi-decadal variability in the TBO transitions is clearly seen in both observational and reanalysis products and climate models.

Coronary artery disease (CAD), underpinned by atherosclerosis, remains a leading cause of morbidity and mortality, particularly in the Western World. Although the advent of percutaneous transluminal coronary angioplasty (PTCA) has provided a fundamental change in the treatment of CAD and drug-eluting stents (DES) have brought about marked improvement, there still remain significant challenges such as restenosis and late stent thrombosis. Coronary artery bypass grafting (CABG) has been acknowledged as the most effective way to treat CAD. However saphenous vein graft failures still present a problem due to stenosis. Vascular smooth muscle cell (VSMC) proliferation and migration is the primary driver of restenosis after percutaneous coronary interventions (PCI) and vein graft failure after CABG. Endothelial dysfunction also plays an important role in both restenosis and late thrombosis following PCI. Therefore, key to the prevention of restenosis and late stent thrombosis is to suppress SMC proliferation and migration, and to enhance re-endothelialisation. The broad aim of work in this thesis is to seek more effective strategies to inhibit SMC hyperplasia and intimal thickening while promoting re-endothelialisation. More specifically, the effects of three kinds of bio-molecules on prevention of restenosis are investigated in this thesis. Firstly, a novel “cocktail” consisting of a combination of VEGF-A, VEGF-D and cRGD, which has not been studied with SMC and EC in response to injury, is tested in a rat carotid balloon injury model. Secondly, the efficacy of the DNAzyme, Dz13, targeting c-Jun is tested in the rabbit autologous vein bypass graft model using the lipid-based transfection agent 1,2- dioleoyl-3-trimethylammonium propane (DOTAP) / 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). Lastly, the anti-restenotic potential of miR-191, a natural microRNA inhibitor of the immediate early gene Egr-1, is examined in the balloon-injured rat carotid artery model. The data presented in this thesis demonstrates that localised delivery of Dz13, miR191 and a novel cocktail of VEGF-A, VEGF-D and cRGD can inhibit neointima formation in animal models. According to these studies, the cocktail, Dz13 and miR191 may be useful approaches for reducing in-stent restenosis and late thrombosis. The ability of these biomolecules to be delivered at a local level makes them ideal for inclusion in stent-based strategies.

Previous studies from our lab showed that terminal Schwann cells (TSCs) are actively involved in the restoration of functional synapses during reinnervation at mammalian neuromuscular junctions (NMJs). However, it is unclear what induces TSCs to extend processes that guide the nerve growth (Son and Thompson, 1995a,b). Is it the loss of the axon or instead, some signal arising from denervated muscle fibers? The main objective of my dissertation was to examine whether muscle fibers can be the source of signals affecting TSC growth. In Chapter 2, I report that both TSCs and nerve terminals are maintained at the former junction even after their underlying muscle fiber degenerates. Some of the original AChRs are surprisingly sustained at the synaptic sites for a long time with the preserved pretzel pattern. These results show that the postsynaptic target is not necessary for the maintenance of presynaptic structures. In Chapter 3, I report that following fiber regeneration, newly formed AChRs are clearly separated from the persisting receptors at most locations and they are apposed by the nerves. Moreover, as the fiber regenerates, TSCs begin to grow processes. Nerve sprouts then follow these processes to form new synaptic sites beyond the old receptor territory. My observations therefore show that signals for nerve growth arise from regenerating fibers and they appear to act by first affecting TSCs. Such signals seem diffusible because I saw that TSCs on surrounding fibers also began to grow during regeneration. In Chapter 4, I report that new junctions on the regenerated fibers are very dynamic. They undergo continual remodeling and eventually take on an 'en grappe' pattern. Since the synapses on undamaged fibers are normally very stable, these observations suggest that regeneration has set in place a process whereby the synapses are unable to stabilize. Interestingly, this appears to be the case in muscles that degenerate as a consequence of muscular dystrophy. My findings are important because they suggest an active role of the postsynaptic muscle fiber not in synapse maintenance but rather in generating signals that attract innervation after injury.

This thesis presents an innovative approach to pattern recognition, by using self-organized, invariant representations integrating continuous observation and saccade movements. This biologically motivated approach can achieve visual perception through a retina like sampling of high resolution images with lower resolution artificial retina. The neural network uses hierarchical feedback structures to build object representations, self-organizes invariant transformations, while iterates on the images received from the retina model. The network identifies the whole image by using winner-take-all scheme through temporal association of sufficiently accurate saccades. By using our invariance building scheme, the network can identify different views of the same object.

As a new technique for structural dynamic analysis, local structural modification is playing a more and more important role in solving practical engineering problems. This thesis develops methods for vibration reduction via local structural modification. In this thesis, the reduction of unwanted vibration in a structural system is principally analysed in two ways, (i) relocation of resonance, and (ii) relocation of anti-resonance - both of which are realised by using local structural modification techniques. The local structural modification is characterised by locally varying the physical parameters of the structural system, and, an algorithm is developed for the finite element implementation. The algorithm which determines the physical parameters to achieve the desired resonances and anti-resonances can be obtained by solving a non-linear polynomial eigen-problem. Examples illustrating the use of various finite element models along with a practical structure are provided to verify the algorithms developed in this thesis and to illustrate the potential of the methods for solving vibration reduction problems in complicated engineering structural systems. In addition, a procedure for structural dynamic optimisation is developed to eliminate the unwanted resonance peak from frequency response functions using the 'POLE-ZERO' cancellation principle via local structural modification. This procedure enables the structural system to preserve certain dynamic properties after structural modification. Numerical and experimental simulations are presented to illustrate the general procedure and to demonstrate the capability of the method.