411 research outputs found

    Undergraduate Catalog of Studies, 2023-2024

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    Undergraduate Catalog of Studies, 2023-2024

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    Undergraduate Catalog of Studies, 2022-2023

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    Rebuilding the Appalachian Economy From the Ground Up: Towards A Holistic Organizational Framework for Community and Economic Development in Rural Extractive Areas

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    Central Appalachia specifically and rural extractive areas more generally face some of the most challenging socio-economic realities in North America. Community-based organizations (CBOs) are an important tool for addressing these challenges. As governments intensify efforts to mitigate climate change, and as fossil-fuel industries contract, extracted communities are experiencing economic, cultural, and environmental upheaval. Many leaders call for a “just transition” away from fossil-fuels, which would make local extraction communities whole. However, achieving a truly just transition away from fossil fuels is extraordinarily challenging, and many extracted communities were never whole to begin with. I argue CBOs are the crucial vehicle through which effective community and economic development (CED) outcomes can materialize for distressed rural communities. Yet CBOs do not receive nearly enough funding, policy-focus, or high-level partnership. Technical assistance provided to CBOs is often ineffective, especially in rural settings. Evaluation systems for measuring rural CBO effectiveness are inadequate. My research is primarily geared toward practitioners and aspiring practitioners. Findings, program designs and evaluative structures put forward herein are based on experience with Coalfield Development, a 501(c)3 non-profit organization I founded in southern West Virginia in 2010. Coalfield Development has essentially served as my research field lab. This dissertation provides four sections detailing organizational capabilities which local CBOs can develop and implement towards the goal of a just transition and improved quality of life for their unique rural place. In doing so, support is needed from funders and policy-makers in order to succeed. Much better evaluative systems are needed, as well, which could improve resource allocation decisions in these greatly under-invested communities and could also improve organizational effectiveness. The four capabilities and corresponding sections of this dissertation are: capacity building for rural CBOs incubating and investing in employment social enterprises human development for people facing barriers to employment and community-based real-estate revitalization In this dissertation, I use mixed-methods to draw insights and best-practices from more than a decade of interventions through Coalfield Development including case studies, focus groups, surveys, cost-benefit-analyses, program designs and program evaluations. My research illustrates and articulates the value of all four capabilities, finding them each as essential components for CBOs working in extracted local economies. While this research is based in central Appalachia it is intended to be useful to practitioners, policymakers, funders, local leaders and researchers in other rural fossil-fuel communities throughout the world

    Is Psychological Safety Increased during the Pre Briefing Phase? A Study of High-fidelity Simulation for Medical Students

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    The purpose of this quantitative, experimental pretest, posttest control group design was to examine if the level of psychological safety a student arrives with to a high-fidelity simulation is predictive of their stress and psychological safety levels after a simulation event. Because recent research has found inconsistencies in the goals of the prebriefing phase of a simulation learning event, there exists the question of whether a facilitator can adequately establish psychological safety during the prebriefing. This study sampled 114 students from a medical school in the mid-Atlantic region of the United States to examine if preexisting psychological safety can predict postsimulation stress and psychological safety when using an intervention of psychological safety elements in the prebriefing and controlling for team cohesion. To measure these items, this study used the Psychological Safety in High-Fidelity Simulation (PSHFS) scale, the Group Cohesion Scale (GCS), and the PSS through a combination of pretest and posttest electronic surveys. The data were analyzed using multiple regression and showed that preexisting psychological safety scores were a significant predictor for both postsimulation stress and psychological safety scores. However, team cohesion and the treatment intervention were not significant predictors. This research suggested the level of psychological safety a learner arrives with to a simulation may have a more significant influence than originally thought in previous research. Future research should explore if elements of providing psychological safety in the prebriefing are exchangeable based on a learner’s preexisting psychological safety

    Techniques intelligentes pour la gestion de la cohérence des Big data dans le cloud

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    Cette thĂšse aborde le problĂšme de cohĂ©rence des donnĂ©es de Bigdata dans le cloud. En effet, nos recherches portent sur l’étude de diffĂ©rentes approches de cohĂ©rence adaptative dans le cloud et la proposition d’une nouvelle approche pour l’environnement Edge computing. La gestion de la cohĂ©rence a des consĂ©quences majeures pour les systĂšmes de stockage distribuĂ©s. Les modĂšles de cohĂ©rence forte nĂ©cessitent une synchronisation aprĂšs chaque mise Ă  jour, ce qui affecte considĂ©rablement les performances et la disponibilitĂ© du systĂšme. À l’inverse, les modĂšles Ă  faible cohĂ©rence offrent de meilleures performances ainsi qu’une meilleure disponibilitĂ© des donnĂ©es. Cependant, ces derniers modĂšles peuvent tolĂ©rer trop d’incohĂ©rences temporaires sous certaines conditions. Par consĂ©quent, une stratĂ©gie de cohĂ©rence adaptative est nĂ©cessaire pour ajuster, pendant l’exĂ©cution, le niveau de cohĂ©rence en fonction de la criticitĂ© des requĂȘtes ou des donnĂ©es. Cette thĂšse apporte deux contributions. Dans la premiĂšre contribution, une analyse comparative des approches de cohĂ©rence adaptative existantes est effectuĂ©e selon un ensemble de critĂšres de comparaison dĂ©finis. Ce type de synthĂšse fournit Ă  l’utilisateur/chercheur une analyse comparative des performances des approches existantes. De plus, il clarifie la pertinence de ces approches pour les systĂšmes cloud candidats. Dans la seconde contribution, nous proposons MinidoteACE, un nouveau systĂšme adaptatif de cohĂ©rence qui est une version amĂ©liorĂ©e de Minidote, un systĂšme de cohĂ©rence causale pour les applications Edge. Contrairement Ă  Minidote qui ne fournit que la cohĂ©rence causale, notre modĂšle permet aux applications d’exĂ©cuter Ă©galement des requĂȘtes avec des garanties de cohĂ©rence plus fortes. Des Ă©valuations expĂ©rimentales montrent que le dĂ©bit ne diminue que de 3,5 % Ă  10 % lors du remplacement d’une opĂ©ration causale par une opĂ©ration forte. Cependant, la latence de mise Ă  jour augmente considĂ©rablement pour les opĂ©rations fortes jusqu’à trois fois pour une charge de travail oĂč le taux des opĂ©rations de mise Ă  jour est de 25 %

    Undergraduate Catalog of Studies, 2022-2023

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    University of Maine Undergraduate Catalog, 2022-2023

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    The University of Maine undergraduate catalog for the 2022-2023 academic year includes an introduction, the academic calendars, general information about the university, and sections on attending, facilities and centers, and colleges and academic programs including the Colleges of Business, Public Policy and Health, Education and Development, Engineering, Liberal Arts and Sciences, and Natural Sciences, Forestry and Agriculture

    Merging Queries in OLTP Workloads

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    OLTP applications are usually executed by a high number of clients in parallel and are typically faced with high throughput demand as well as a constraint latency requirement for individual statements. In enterprise scenarios, they often face the challenge to deal with overload spikes resulting from events such as Cyber Monday or Black Friday. The traditional solution to prevent running out of resources and thus coping with such spikes is to use a significant over-provisioning of the underlying infrastructure. In this thesis, we analyze real enterprise OLTP workloads with respect to statement types, complexity, and hot-spot statements. Interestingly, our findings reveal that workloads are often read-heavy and comprise similar query patterns, which provides a potential to share work of statements belonging to different transactions. In the past, resource sharing has been extensively studied for OLAP workloads. Naturally, the question arises, why studies mainly focus on OLAP and not on OLTP workloads? At first sight, OLTP queries often consist of simple calculations, such as index look-ups with little sharing potential. In consequence, such queries – due to their short execution time – may not have enough potential for the additional overhead. In addition, OLTP workloads do not only execute read operations but also updates. Therefore, sharing work needs to obey transactional semantics, such as the given isolation level and read-your-own-writes. This thesis presents THE LEVIATHAN, a novel batching scheme for OLTP workloads, an approach for merging read statements within interactively submitted multi-statement transactions consisting of reads and updates. Our main idea is to merge the execution of statements by merging their plans, thus being able to merge the execution of not only complex, but also simple calculations, such as the aforementioned index look-up. We identify mergeable statements by pattern matching of prepared statement plans, which comes with low overhead. For obeying the isolation level properties and providing read-your-own-writes, we first define a formal framework for merging transactions running under a given isolation level and provide insights into a prototypical implementation of merging within a commercial database system. Our experimental evaluation shows that, depending on the isolation level, the load in the system, and the read-share of the workload, an improvement of the transaction throughput by up to a factor of 2.5x is possible without compromising the transactional semantics. Another interesting effect we show is that with our strategy, we can increase the throughput of a real enterprise workload by 20%.:1 INTRODUCTION 1.1 Summary of Contributions 1.2 Outline 2 WORKLOAD ANALYSIS 2.1 Analyzing OLTP Benchmarks 2.1.1 YCSB 2.1.2 TATP 2.1.3 TPC Benchmark Scenarios 2.1.4 Summary 2.2 Analyzing OLTP Workloads from Open Source Projects 2.2.1 Characteristics of Workloads 2.2.2 Summary 2.3 Analyzing Enterprise OLTP Workloads 2.3.1 Overview of Reports about OLTP Workload Characteristics 2.3.2 Analysis of SAP Hybris Workload 2.3.3 Summary 2.4 Conclusion 3 RELATED WORK ON QUERY MERGING 3.1 Merging the Execution of Operators 3.2 Merging the Execution of Subplans 3.3 Merging the Results of Subplans 3.4 Merging the Execution of Full Plans 3.5 Miscellaneous Works on Merging 3.6 Discussion 4 MERGING STATEMENTS IN MULTI STATEMENT TRANSACTIONS 4.1 Overview of Our Approach 4.1.1 Examples 4.1.2 Why Naïve Merging Fails 4.2 THE LEVIATHAN Approach 4.3 Formalizing THE LEVIATHAN Approach 4.3.1 Transaction Theory 4.3.2 Merging Under MVCC 4.4 Merging Reads Under Different Isolation Levels 4.4.1 Read Uncommitted 4.4.2 Read Committed 4.4.3 Repeatable Read 4.4.4 Snapshot Isolation 4.4.5 Serializable 4.4.6 Discussion 4.5 Merging Writes Under Different Isolation Levels 4.5.1 Read Uncommitted 4.5.2 Read Committed 4.5.3 Snapshot Isolation 4.5.4 Serializable 4.5.5 Handling Dependencies 4.5.6 Discussion 5 SYSTEM MODEL 5.1 Definition of the Term “Overload” 5.2 Basic Queuing Model 5.2.1 Option (1): Replacement with a Merger Thread 5.2.2 Option (2): Adding Merger Thread 5.2.3 Using Multiple Merger Threads 5.2.4 Evaluation 5.3 Extended Queue Model 5.3.1 Option (1): Replacement with a Merger Thread 5.3.2 Option (2): Adding Merger Thread 5.3.3 Evaluation 6 IMPLEMENTATION 6.1 Background: SAP HANA 6.2 System Design 6.2.1 Read Committed 6.2.2 Snapshot Isolation 6.3 Merger Component 6.3.1 Overview 6.3.2 Dequeuing 6.3.3 Merging 6.3.4 Sending 6.3.5 Updating MTx State 6.4 Challenges in the Implementation of Merging Writes 6.4.1 SQL String Implementation 6.4.2 Update Count 6.4.3 Error Propagation 6.4.4 Abort and Rollback 7 EVALUATION 7.1 Benchmark Settings 7.2 System Settings 7.2.1 Experiment I: End-to-end Response Time Within a SAP Hybris System 7.2.2 Experiment II: Dequeuing Strategy 7.2.3 Experiment III: Merging Improvement on Different Statement, Transaction and Workload Types 7.2.4 Experiment IV: End-to-End Latency in YCSB 7.2.5 Experiment V: Breakdown of Execution in YCSB 7.2.6 Discussion of System Settings 7.3 Merging in Interactive Transactions 7.3.1 Experiment VI: Merging TATP in Read Uncommitted 7.3.2 Experiment VII: Merging TATP in Read Committed 7.3.3 Experiment VIII: Merging TATP in Snapshot Isolation 7.4 Merging Queries in Stored Procedures Experiment IX: Merging TATP Stored Procedures in Read Committed 7.5 Merging SAP Hybris 7.5.1 Experiment X: CPU-time Breakdown on HANA Components 7.5.2 Experiment XI: Merging Media Query in SAP Hybris 7.5.3 Discussion of our Results in Comparison with Related Work 8 CONCLUSION 8.1 Summary 8.2 Future Research Directions REFERENCES A UML CLASS DIAGRAM
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