1,070 research outputs found

    ENHANCING CLOUD SYSTEM RUNTIME TO ADDRESS COMPLEX FAILURES

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    As the reliance on cloud systems intensifies in our progressively digital world, understanding and reinforcing their reliability becomes more crucial than ever. Despite impressive advancements in augmenting the resilience of cloud systems, the growing incidence of complex failures now poses a substantial challenge to the availability of these systems. With cloud systems continuing to scale and increase in complexity, failures not only become more elusive to detect but can also lead to more catastrophic consequences. Such failures question the foundational premises of conventional fault-tolerance designs, necessitating the creation of novel system designs to counteract them. This dissertation aims to enhance distributed systems’ capabilities to detect, localize, and react to complex failures at runtime. To this end, this dissertation makes contributions to address three emerging categories of failures in cloud systems. The first part delves into the investigation of partial failures, introducing OmegaGen, a tool adept at generating tailored checkers for detecting and localizing such failures. The second part grapples with silent semantic failures prevalent in cloud systems, showcasing our study findings, and introducing Oathkeeper, a tool that leverages past failures to infer rules and expose these silent issues. The third part explores solutions to slow failures via RESIN, a framework specifically designed to detect, diagnose, and mitigate memory leaks in cloud-scale infrastructures, developed in collaboration with Microsoft Azure. The dissertation concludes by offering insights into future directions for the construction of reliable cloud systems

    The Individual And Their World

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    Towards a Digital Capability Maturity Framework for Tertiary Institutions

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    Background: The Digital Capability (DC) of an Institution is the extent to which the institution's culture, policies, and infrastructure enable and support digital practices (Killen et al., 2017), and maturity is the continuous improvement of those capabilities. As technology continues to evolve, it is likely to give rise to constant changes in teaching and learning, potentially disrupting Tertiary Education Institutions (TEIs) and making existing organisational models less effective. An institution’s ability to adapt to continuously changing technology depends on the change in culture and leadership decisions within the individual institutions. Change without structure leads to inefficiencies, evident across the Nigerian TEI landscape. These inefficiencies can be attributed mainly to a lack of clarity and agreement on a development structure. Objectives: This research aims to design a structure with a pathway to maturity, to support the continuous improvement of DC in TEIs in Nigeria and consequently improve the success of digital education programmes. Methods: I started by conducting a Systematic Literature Review (SLR) investigating the body of knowledge on DC, its composition, the relationship between its elements and their respective impact on the Maturity of TEIs. Findings from the review led me to investigate further the key roles instrumental in developing Digital Capability Maturity in Tertiary Institutions (DCMiTI). The results of these investigations formed the initial ideas and constructs upon which the proposed structure was built. I then explored a combination of quantitative and qualitative methods to substantiate the initial constructs and gain a deeper understanding of the relationships between elements/sub-elements. Next, I used triangulation as a vehicle to expand the validity of the findings by replicating the methods in a case study of TEIs in Nigeria. Finally, after using the validated constructs and knowledge base to propose a structure based on CMMI concepts, I conducted an expert panel workshop to test the model’s validity. Results: I consolidated the body of knowledge from the SLR into a universal classification of 10 elements, each comprising sub-elements. I also went on to propose a classification for DCMiTI. The elements/sub-elements in the classification indicate the success factors for digital maturity, which were also found to positively impact the ability to design, deploy and sustain digital education. These findings were confirmed in a UK University and triangulated in a case study of Northwest Nigeria. The case study confirmed the literature findings on the status of DCMiTI in Nigeria and provided sufficient evidence to suggest that a maturity structure would be a well-suited solution to supporting DCM in the region. I thus scoped, designed, and populated a domain-specific framework for DCMiTI, configured to support the educational landscape in Northwest Nigeria. Conclusion: The proposed DCMiTI framework enables TEIs to assess their maturity level across the various capability elements and reports on DCM as a whole. It provides guidance on the criteria that must be satisfied to achieve higher levels of digital maturity. The framework received expert validation, as domain experts agreed that the proposed Framework was well applicable to developing DCMiTI and would be a valuable tool to support TEIs in delivering successful digital education. Recommendations were made to engage in further iterations of testing by deploying the proposed framework for use in TEI to confirm the extent of its generalisability and acceptability

    Measuring the impact of COVID-19 on hospital care pathways

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    Care pathways in hospitals around the world reported significant disruption during the recent COVID-19 pandemic but measuring the actual impact is more problematic. Process mining can be useful for hospital management to measure the conformance of real-life care to what might be considered normal operations. In this study, we aim to demonstrate that process mining can be used to investigate process changes associated with complex disruptive events. We studied perturbations to accident and emergency (A &E) and maternity pathways in a UK public hospital during the COVID-19 pandemic. Co-incidentally the hospital had implemented a Command Centre approach for patient-flow management affording an opportunity to study both the planned improvement and the disruption due to the pandemic. Our study proposes and demonstrates a method for measuring and investigating the impact of such planned and unplanned disruptions affecting hospital care pathways. We found that during the pandemic, both A &E and maternity pathways had measurable reductions in the mean length of stay and a measurable drop in the percentage of pathways conforming to normative models. There were no distinctive patterns of monthly mean values of length of stay nor conformance throughout the phases of the installation of the hospital’s new Command Centre approach. Due to a deficit in the available A &E data, the findings for A &E pathways could not be interpreted

    How do adult survivors of childhood abuse, experience and understand their capacity to trust in relationships?

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    How do adult survivors of childhood abuse, experience and understand their capacity to trust in relationships? Feedback from adults with histories of developmental trauma indicated they experienced considerable difficulties ‘trusting in others generally’, which had significant consequences for their overall quality of life. Using a classic grounded theory design, this study examined the relational trust recovery paths of 13 (10 female, 3 male) survivors of childhood abuse to develop a three-phased model of recovery that highlighted the significance of the therapeutic relationship (Initializing phase), live experimentation (Input phase), and an internal journey from a traumatized self to a more empowered self-concept (Processing phase). The therapeutic work within each phase is described along with a suggested role for motivation to learn theories (Expectancy-Value and Attribution theories), specifically the potential contribution of ‘expectancy of success’ and ‘task value’ to motivate movement through the process. The internal journey to a more positive sense of self varied for each participant; however, in all cases, a reported shift in feelings of ‘personal agency’ and ‘selfïżœefficacy’ facilitated positive adjustment(s) to connect with others. Central to making positive changes was growth in the relational skillsets in two key areas, ‘feeling valued’ characterized by improved self-acceptance, self-esteem, and self-efficacy, and ‘adaptive and flexible responsiveness’ characterized by self-confidence, self-acceptance, and engagement. The therapeutic journey was perceived as challenging and fraught with risk and setbacks; however, perseverance brought the much-cherished rewards of a more trusting relationship with the self and others

    The Russian Empire, Slaving and Liberation, 1480–1725

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    The monograph realigns political culture and countermeasures against slave raids, which rose during the breakup of the Golden Horde. By physical defense of the open steppe border and embracing the New Israel symbolism (exodus from slavery in Egypt/among the Tatars), Muscovites found a defensive model to expand the empire. Recent debates on slaving are introduced to Russian and imperial history, while challenging entrenched perceptions of Muscovy

    Operational Research: methods and applications

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    This is the final version. Available on open access from Taylor & Francis via the DOI in this recordThroughout its history, Operational Research has evolved to include methods, models and algorithms that have been applied to a wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first summarises the up-to-date knowledge and provides an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion and used as a point of reference by a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes
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