M.Com. (Accounting) / Please refer to full text to view abstract

The current public food assistance system in the United States depends primarily on delivery through vouchers provided to families who cannot afford adequate food due to economic hardship that they can use in retail markets to purchase food. However, how to conceptualize, define, measure, and determine the importance of access to food retail for the nearly 50 million food insecure people in the U.S. remains a challenge. These three papers provide three different methods for measuring food access in the rural context with diverging purposes and applications, moving from simple conceptions of access to more complex approaches that combine quantitative and qualitative measures. I seek to answer the question: How can critical GIS be used to better understand the relationship between access to food retailers, public nutrition assistance programs, and food shopping patterns in rural Arizona? This question is further refined by three sub-questions: How can GIS be used to develop a better measure of physical access to food retail for nutrition assistance recipients in rural areas? What are the barriers to food access for recipients beyond physical access, and how can these be incorporated into measures of accessibility? How does accessibility of food retail affect recipients’ food shopping habits? Through using a grounded mixed-methods approach, I hope to integrate quantitative measures of access with qualitative insight into individual intentions and lived experience in using public assistance benefits to shop for food. Taken together, these papers provide a broad view on how to better quantify and measure food access in the rural setting, as well as avenues for further development of access measures and interventions to ensure equity in food access for all.

Vascular access (VA) is one of the most important determinants of outcomes in haemodialysis (HD). Poor VA outcomes have a significant adverse impact on patient experience, morbidity and mortality and also result in significant burden on the health economy. An arteriovenous fistula (AVF) is accepted as the best HD vascular access. However AVF prevalence is variable and AVFs are associated with a high early failure rate. A small but significant number of AVFs experience late failure further down the line. The purpose of this project, broadly, was to understand VA outcomes, focusing specifically on AVFs. This project involved a series of clinical studies that were specifically designed by the student researcher to investigate various time points in the life cycle of AVFs – from creation and maturation - to its use and subsequent failure. The MANVAS, OPEN and Coil embolisation studies focus on the early phase of AVF development and maturation, whilst, the VA in Home HD study investigates the impact of intensive self-use in a non-healthcare setting. It is followed by the prospective thrombosed vascular access study focusing on the late phase of VA failure. The MANVAS study, a prospective cohort study, was set up with an aim to follow up patients undergoing AVF formation with a view to defining the natural history and maturation process of AVFs, and determine factors which affect outcomes – demographic, clinical, and biological. The OPEN study was designed to investigate poor maturation due to anastomotic failure by the intervention of the OptiflowTM device. The results suggest high maturation rates that were significantly better than those reported in the literature. The coil embolisation study demonstrated that the intervention of coil embolisation is a safe and effective treatment option for failing AVFs with accessory draining veins. The Vascular Access in Home Haemodialysis (HHD) study demonstrated that VA outcomes are significantly better in HHD patients and unadjusted patient survival in the HHD cohort was associated with incident VA. The thrombosed access study is a prospective longitudinal study designed to assess the effectiveness of endovascular access salvage and investigation of factors that impact longer-term access survival. One of the major aims of the study was to analyse outcomes related to prompt restoration of flow for patients presenting with acute failure of fistulae and grafts. The study showed that timely endovascular salvage is highly effective in restoring immediate patency but long-term outcomes remain poor. It also confirms poor outcomes of grafts as compared to AVFs and demonstrates that progression to thrombosis in AVFs portends poorer prognosis. The endovascular technique of balloon maceration, compared to outcomes reported in the literature, appears to be equally safe and effective with no increased risk of clinically significant pulmonary embolism. The clinical studies in this thesis provide a unique insight into the different aspects of the lifecycle of an AVF, and pave the way for an improvement in our fundamental understanding of the natural history and biology of AVFs.

M.Sc. / The aim of this dissertation (referred to as thesis in the rest of the document) is to investigate the concept of Single Sign-on (SSO) in heterogeneous computing environments and to provide guidelines and reference frameworks for the selection and successful implementation of SSO solutions. In doing so. it also provides an overview of the basic types of SSO, Secure Single Sign-on (SSSO) solutions, enabling technologies, as well as products currently available. Chapter 1 introduces the sign-on problem, the purpose and organization of the thesis and terminology and abbreviations used. The crux of the sign-on problem is that users are required to sign on to multiple systems, developed at different times and based on different technologies, each with its own set of signon procedures and passwords. This inevitably leads to frustration, loss of productivity and weakened security. Users frequently resort to writing down passwords or using trivial password that can easily be guessed. In Chapter 2 the concepts of Single Sign-on and a special subset of SSO, Secure Single Sign-on are defined. Five types of SSO solutions are identified, namely: Synchronization, Scripting, Proxies and Trusted Hosts. Trusted Authentication Server and Hybrid solutions. Of the available types of solutions, only Trusted Authentication Server and Hybrid solutions can provide Secure Single Sign-on if properly implemented. The security services for SSSO are identified as authentication, authorization, integrity, confidentiality, non-repudiation, security management and cryptographic services. Additional SSSO concepts, as well as the vulnerabilities, obstacles and pitfalls to introducing SSO solutions are discussed. Chapter 3 provides an overview of the most important SSO enabling technologies. The following technologies are discussed: OSF DCE, SESAME, Kerberos, DSSA/SPX, TESS, NetSp, Secure Tokens, GSS-API and Public key Cryptography. Chapter 4 discusses the Open Software Foundation's (OSF) Distributed Computing Environment (DCE). OSF DCE is one of the two open standards for distributed processing which are having a major influence on the development of single sign-on solutions and forms the basis of many existing SSO products. DCE is not a SSO product. but consists of specifications and software. The goal of DCE is to turn a computer network into a single, coherent computing engine. It is considered to be one of the fundamental building blocks for SSO solutions in the future. In Chapter 5 SESAME is discussed in some detail as another major enabling technology for SSO. Secure European System for Applications in a Multi-vendor Environment (SESAME) is an architecture that implements a model for the provision of security services within open systems developed by the European Computer Manufacturers Association (ECMA). The architecture was developed and implemented on a trial basis, by Bull, ICL and Siemens-Nixdorf in an initiative supported by the European Commission. Chapter 6 presents a list of 49 commercial SSO products currently available, classified according to the type of SSO solution. A few representative products are discussed in more detail to give an indication what functionality a prospective buyer could expect. The 'Ideal Single Sign-on' solution is presented in Chapter 7. Detailed requirements are listed. These requirements are uniquely identified by a code and classified as essential or recommended functionality required. Chapter 8 assimilates the information in the previous chapters into a structured evaluation, selection and implementation plan for SSO solutions, consisting of nine separate phases. It also proposes a reference framework for the evaluation and selection process. Chapter 9 concludes the thesis. Findings and conclusions are summarized as to the importance and impact of Single Sign-on as well as the expected future directions to be expected. In addition, recommendations for the future implementation of SSO and SSSO solutions in heterogeneous computing environments are made.

The purpose of this study is to propose a top-down policy engineering framework for attribute-based access control (ABAC) that aims to automatically extract ACPs from requirement specifications documents, and then, using the extracted policies, build or update an ABAC model. We specify a procedure that consists of three main components: 1) ACP sentence identification, 2) policy element extraction, and 3) ABAC model creation and update. ACP sentence identification processes unrestricted natural language documents and identify the sentences that carry ACP content. We propose and compare three different methodologies from different disciplines, namely deep recurrent neural networks (RNN-based), biological immune system (BIS-based), and a combination of multiple natural language processing techniques (PMI-based) in order to identify the proper methodology for extracting ACP sentences from irrelevant text. Our evaluation results improve the state-of-the-art by a margin of 5% F1-Measure. To aid future research, we also introduce a new dataset that includes 5000 sentences from real-world policy documents. ABAC policy extraction extracts ACP elements such as subject, object, and action from the identified ACPs. We use semantic roles and correctly identify ACP elements with an average F1 score of 75%, which bests the previous work by 15%. Furthermore, as SRL tools are often trained on publicly available corpora such as Wall Street Journal, we investigate the idea of improving SRL performance using domain-related knowledge. We utilize domain adaptation and semi-supervised learning techniques and improve the SRL performance by 2% using only a small amount of access control data. The third component, ABAC model creation and update, builds a new ABAC model or updates an existing one using the extracted ACP elements. For this purpose, we present an efficient methodology based on a particle swarm optimization algorithm for solving ABAC policy mining with minimal perturbation. Experimental results demonstrate that the proposed methodology generates much less complex policies than previous works using the same realistic case studies. Furthermore, we perform experiments on how to find an ABAC state as similar as possible to both the existing state and the optimal state. Part of the data utilized in this study was collected from the University of North Texas Policy Office, as well as policy documents from the university of North Texas Health Science Center, for the school years 2015-2016 through 2016-2017.

Today, the use of embedded Dynamic Random Access Memory (eDRAM) is increasing in our electronics that require large memories, such as gaming consoles and computer network routers. Unlike external DRAMs, eDRAMs are embedded inside ASICs for faster read and write operations. Until recently, eDRAMs required high manufacturing cost. Present process technology developments enabled the manufacturing of eDRAM at competitive costs. Unlike SRAM, eDRAM exhibits retention time bit fails from defects and capacitor leakage current. This retention time fail causes memory bits to lose stored values before refresh. Also, a small portion of the memory bits are known to fail at a random retention time. At test conditions, more stringent than use conditions, if all possible retention time fail bits are detected and replaced, there will be no additional fail bits during use. However, detecting all the retention time fails requires long time and also rejects bits that do not fail at the use condition. This research seeks to maximize the detection of eDRAM fail bits during test by determining effective test conditions and model the failure rate of eDRAM retention time during use conditions.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17874号 / 工博第3783号 / 新制||工||1578(附属図書館) / 30694 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 谷口 栄一, 教授 藤井 聡, 教授 清野 純史 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The terrorist attacks of September 11, 2001 propelled the issue of aviation security to the forefront of the U.S. domestic agenda. Although hundreds of individual airports exist in the U.S., the travel activities at each of these airports combine to holistically comprise an aviation system that represents a significant portion of the U.S. social and economic infrastructure. Disruption at one airport resulting from a criminal act, such as terrorism, could exert detrimental effects upon the aviation system and U.S national security (9/11 Commission, 2004). Each U.S. airport is individually responsible for various aspects of security including the control of physical access to sensitive and secure areas and facilities (9/11 Commission, 2004). Biometric technology has been examined as one method of enhancing airport access control to mitigate the possibility of criminal acts against airports. However, successful implementation of biometric technology depends largely on how individual security directors at each airport perceive, understand, and accept that technology. Backgrounds, attitudes, and personal characteristics influence individual decisions about technology implementation (Rogers, 1995; Tornatzky and Fleischer, 1990). This study examines the problem of airport access control, as well as, the current trends in biometric technology. Utilizing a survey of airport security directors and security managers, this study draws upon innovation diffusion theory and organizational theories to determine what personal, organizational, and technical variables contribute to the propensity of airport security directors and managers to adopt biometric technology for airport access control.

In Canada, less than half of the drugs that the World Health Organization classifies as Essential Medicines for the treatment of Neglected Diseases like Chagas disease, drug-resistant tuberculosis, echinococcosis, leishmaniasis, leprosy, malaria and sleeping sickness are formally available, even as collectively hundreds of patients require access to them each year. Essential Medicines, according to the WHO, are those “intended to be available within the context of functioning health systems at all times in adequate amounts, in the appropriate dosage forms, with assured quality, and at a price the individual and the community can afford”. Nevertheless, many of these Essential Medicines, like the conditions they treat, are neglected by pharmaceutical companies and governments alike in low-burden, high-income countries like Canada. The result is a reversal of the usual access to medicines narrative around novel, patented medicines unavailable in low-income countries; these are old, off-patent Essential Medicines, many of which have become widely available in low and middle-income countries yet increasingly difficult to access in many high-income countries. Their absence from countries like Canada is not due to their lack of medical utility – many of them are recognized domestically as the standard of care – but their lack of commercial value. Unfortunately, Canada’s regulatory system is premised upon keeping unsafe, ineffective or poor-quality drugs out, not bringing Essential Medicines in. As a result, these drugs must be accessed through ill-fitting mechanisms like Canada’s Special Access Programme (SAP). Other high-income countries face similar access challenges, though they may manifest in different ways; in the United States for instance, drugs that have disappeared from the Canadian market or simply never been introduced in the first place have instead had de facto monopolies unscrupulously exploited. In turn, as the COVID-19 pandemic has served to underscore, access to these Essential Medicines for Neglected Diseases is an issue that cannot be solved solely at the domestic level. Essential Medicines that threaten to disappear before the diseases they treat do also serve to highlight broader issues of domestic and international concern, from drug shortages to antimicrobial resistance. This thesis provides an in-depth exploration of the problem, and offers guidance on what Canada in particular can do about improving access to medicines, especially those for Neglected Diseases that have been largely absent from the Canadian pharmaceutical agenda.

To support wireless-oriented services, a new generation of Web services called Mobile services (M-services) has emerged. M-services provide mobile users access to services through wireless networks. One of the important issues in M-service environment is how to discover and access M-services efficiently. In this dissertation, we propose time and power efficient access methods for M-services. We focus on methods for accessing broadcast based M-services from multiple wireless channels. We first discuss efficient access methods in data-oriented wireless broadcast systems. We then discuss how to extend current wireless broadcast systems to support simple M-services. We present a novel infrastructure that provides a multi-channel broadcast framework for mobile users to effectively discover and access composite M-services. Multi-channel algorithms are proposed for efficiently accessing composite services. We define a few semantics that have impact on access efficiency in the proposed infrastructure. We discuss semantic access to composite services. Broadcast channel organizations suitable for discovering and accessing composite services are proposed. We also derive analytical models for these channel organizations. To provide practical study for the proposed infrastructure and access methods, a testbed is developed for simulating accessing M-services in a broadcast-based environment. Extensive experiments have been conducted to study the proposed access methods and broadcast channel organizations. The experimental results are presented and discussed. / Ph. D.