abstract: Access control is one of the most fundamental security mechanisms used in the design and management of modern information systems. However, there still exists an open question on how formal access control models can be automatically analyzed and fully realized in secure system development. Furthermore, specifying and managing access control policies are often error-prone due to the lack of effective analysis mechanisms and tools. In this dissertation, I present an Assurance Management Framework (AMF) that is designed to cope with various assurance management requirements from both access control system development and policy-based computing. On one hand, the AMF framework facilitates comprehensive analysis and thorough realization of formal access control models in secure system development. I demonstrate how this method can be applied to build role-based access control systems by adopting the NIST/ANSI RBAC standard as an underlying security model. On the other hand, the AMF framework ensures the correctness of access control policies in policy-based computing through automated reasoning techniques and anomaly management mechanisms. A systematic method is presented to formulate XACML in Answer Set Programming (ASP) that allows users to leverage off-the-shelf ASP solvers for a variety of analysis services. In addition, I introduce a novel anomaly management mechanism, along with a grid-based visualization approach, which enables systematic and effective detection and resolution of policy anomalies. I further evaluate the AMF framework through modeling and analyzing multiparty access control in Online Social Networks (OSNs). A MultiParty Access Control (MPAC) model is formulated to capture the essence of multiparty authorization requirements in OSNs. In particular, I show how AMF can be applied to OSNs for identifying and resolving privacy conflicts, and representing and reasoning about MPAC model and policy. To demonstrate the feasibility of the proposed methodology, a suite of proof-of-concept prototype systems is implemented as well. / Dissertation/Thesis / Ph.D. Computer Science 2012

Context. With the development of computer software, hardware, and communication technologies, a new type of human-centered computing model, called Cloud Computing (CC) has been established as a commercial computer network service. However, the openness of CC brings huge security challenge to the identity-based access control system, as it not able to effectively prevent malicious users accessing; information security problems, system stability problems, and also the trust issues between cloud service users (CSUs) and cloud service providers (CSPs) are arising therefrom. User behavior trust (UBT) evaluation is a valid method to solve security dilemmas of identity-based access control system, but current studies of UBT based access control model is still not mature enough, existing the problems like UBT evaluation complexity, trust dynamic update efficiency, evaluation accuracy, etc. Objective. The aim of the study is to design and develop an improved UBT based CC access control model compare to the current state-of-art. Including an improved UBT evaluation method, able to reflect the user’s credibility according to the user’s interaction behavior, provides access control model with valid evidence to making access control decision; and a dynamic authorization control and re-allocation strategy, able to timely response to user’s malicious behavior during entire interaction process through real-time behavior trust evaluation. Timely updating CSUs trust value and re-allocating authority degree. Methods. This study presented a systematical literature review (SLR) to identify the working structure of UBT based access control model; summarize the CSUs’ behaviors that can be collected as UBT evaluation evidence; identify the attributes of trust that will affect the accuracy of UBT evaluation; and evaluated the current state-of-art of UBT based access control models and their potential advantages, opportunities, and weaknesses. Using the acquired knowledge, design a UBT based access control model, and adopt prototype method to simulate the performance of the model, in order to verify its validation, verify improvements, and limitations. Results. Through the SLR, two types of UBT based access control model working structures are identified and illustrated, essential elements are summarized, and a dynamic trust and access update module is described; 23 CSU’s behavior evidence items are identified and classified into three classes; four important trust attributes, influences, and corresponding countermeasures are identified and summarized; and eight current state-of-art of UBT based access control models are identified and evaluated. A Triple Dynamic Window based Access Control model (TDW) was designed and established as a prototype, the simulation result indicates the TDW model is well performed on the trust fraud problem and trust expiration problem. Conclusions. From the research results that we obtained from this study, we have identified several basic elements of UBT evaluation method, evaluated the current state-of-art UBT based access control models. Towards the weaknesses of trust fraud prevention and trust expiration problem, this paper designed a TDW based access control model. In comparing to the current state-of-art of UBT models, the TDW model has the following advantages, such as it is effectively preventing trust fraud problem with “slow rise” principle, able to timely response to malicious behavior by constantly aggravate punishment strategy (“rapid decrease” principle), effectively prevent malicious behavior and malicious user, and able to reflect the recent credibility of accessing user by expired trust update strategy and most recent trust calculation; finally, it has simple and customizable data structure, simple trust evaluation method, which has good scalability.

For decades, sexual expression in older adulthood was a taboo topic in the public discourse and ignored in the empirical literature. As a result of several significant sociocultural changes and medical developments as well as an increasingly older population, however, perspectives are shifting and acceptance and interest in the sexual lives of older adults is growing. The purpose of this dissertation was to investigate sexual well-being in older adulthood and explore its diversity. Study 1 involved a systematic review of the literature on factors associated with the maintenance and cessation of sexual activity in adults 60 years of age and older. Data were extracted from a total of 57 studies and each was assessed for methodological quality. Surprisingly, only four factors (i.e., partner’s interest in sexual activity, past frequency of sexual activity, presence of erectile dysfunction, and partner-related illness) were consistently related, in more than one study, to whether or not older adults were sexually active. Significant variability in study results highlighted methodological caveats of the body of literature, but also the heterogeneity of older adults’ sexuality. Study 2 built upon the findings and recommendations of Study 1 and further examined diversity in sexual well-being. Sexual function and satisfaction, the absence of sexuality-related distress, breadth of sexual experience, and overall frequency of sexual activity were considered as indicators of sexual well-being. The Dual Control Model of Sexual Response (DCM) was used as the theoretical framework in this study of women 50 years of age and older. The DCM posits that sexual response depends on the relative activation of sexual excitatory and sexual inhibitory processes, two separate and independent systems. Study 2 results indicated that, independently, women’s propensities for sexual excitation and sexual inhibition were significantly associated with the majority of the indicators of sexual well-being and the directions of associations were consistent with the tenets of the DCM. The only association that proved not statistically significant was the relationship between sexual excitation and sexual distress. When examined together, sexual excitation and sexual inhibition factors significantly predicted sexual function, satisfaction, and frequency. Sexual distress was predicted more strongly by sexual inhibition factors and sexual breadth by sexual excitation factors. Partner physical and mental health and participant mental health were further identified as moderating variables of these associations. The results of Study 2 expand current knowledge regarding the DCM and its relevance to older women; sexual excitation and sexual inhibition appear to have heuristic value to better understand the variability in sexual activity and well-being in women aged 50 years and older. The results of this dissertation have important implications for the study of sexuality and ageing, perhaps most prominently in terms of highlighting the inter-individual variation in older adulthood and the conclusion that generalizations about “older adults” as a group may not be appropriate.

The purpose of the study was to examine social workers 'experience of work-related stress atthe investigation unit for children, young people and families. Five semi-structuredinterviews were done. Results were analyzed using previous research, the requirementscontrol-support model and ’’sense of coherence’’ (SOC) as theoretical starting points. Theresults of the study show that the social workers who participated had a similar experience ofwork-related stress. The stress occurred because of the workload. An informant's experienceof stress differed from other informants as that informant's work-related stress wasknowledge-based. The results analysis shows that four out of five informants were in a tensejob based on requirements-control-support model due to the demands placed and the controlcarried out by the social workers being out of balance. An informant was at an active job andhad a higher SOC than the rest. All informants mention some type of support given to helpdeal with the work-related stress, how much this support helps the social workers havedifferent opinions about. The informants gave different suggestions for changes for the workrelated stress to reduce, but all suggestions lead to the factor that there is a shortage of staffand high staff turnover. / Syftet med studien var att undersöka socialsekreterares upplevelse av arbetsrelaterad stresspå utredningsenhet barn, ungdom och familj. Genom målstyrt bekvämlighetsurvalgenomfördes fem enskilda semistrukturerade intervjuer för att insamla empiri. Dessatranskriberades och tematiserades. Resultatet analyserades med hjälp av tidigare forskning,krav-kontroll-stödmodellen och ‘’känsla av sammanhang’’(KASAM) som teoretiskautgångspunkter. Under arbetets gång framträdde tre teman. Studiens resultat visar att fyraav fem socialsekreterare upplevde att stressen beror på den arbetsbelastning arbetsplatsenpräglas av. En informants upplevelse av stress skiljde sig från andra informanter dåinformantens arbetsrelaterade stress var kunskapsbaserad. Resultatanalysen visar på att fyraav fem informanter befann sig på ett spänt arbete enligt krav-kontroll och stöd modellen ochhade lägre KASAM jämfört med och en informant befann sig på aktivt arbete och hade högreKASAM. Alla informanter nämner någon typ av stöd som ges för att hjälpa till med atthantera den arbetsrelaterade stressen som uppstår, hur mycket detta stöd hjälper är det olikaåsikter om. De förslagen till förändring som uppgavs för att minska den arbetsrelateradestressen var olika, samtliga förslagen leder dock slutligen till det faktorn att det är brist påbemanning och hög personalomsättning.

As the development of highways, it is quite normal for buses running in a speed around 100km/h. When buses are running in a high speed, they may suffer from the influence of side wind disturbances at anytime. Sometimes, it may result in traffic accidents. Therefore, the study of bus stability under side wind disturbances becomes more and more important. Due to restrictions of real tests, computer simulation can be used to study this subject. The bus side wind response character is reflected through the driver’s manoeuvre , so open-loop analysis is hard to give a comprehensive evaluation of the side wind stability of the bus. Therefore, closed-loop analysis is studied in this thesis. An ADAMS bus model and a side wind force model are developed in this thesis, along with two driver models, the PID control model and the preview curvature model. The driver models are built in Simulink and co-simulation between ADAMS/View and Simulink is conducted. The results of co-simulation show that the two driver models can both control the bus from deviating from the desired course under side wind disturbances. The PID control model is simple and shows a very good control effect. The maximum lateral displacement of the bus by PID control model is just 0.0205m under maximum side wind load 1000N and 2500Nm when preview time is 1.2s, while it is 0.0702m by preview curvature model, however, it is difficult to determine the coefficients Kd, Kp, and Ki in the PID controller. The preview curvature model also shows a good control effect in terms of the maximum lateral displacement and yaw angle of the bus. Comparing these two models, the PID control model is more sensitive to deviations, with quicker response and larger steering input. The bus model system is stable under side wind disturbances. Through driver ’s proper steering manoeuvre, the bus is well controlled. The closed-loop analysis is a good method to study the bus stability under side wind disturbances.

The purpose of this study is to add an understanding on the relationship between characteristics of prison population and environmental characteristics of prisons with prison misconduct in the context of Japan, where little empirical research on prison misconduct has been conducted. To aid in the analysis, three theories (the deprivation, importation, and administrative control models) that had been developed in Western countries will be utilized. This study will test thirteen predictors derived from these theories. Using time-series data obtained from annual official reports of Japanese prisons between 1972 and 2019, the relationships between characteristics of prison population (gender, age, violent conviction, criminality, and health problems) and environmental characteristic of prisons or environment-driven characteristics of prisoners (occupancy rate, sentence length, foreign prisoners, drug conviction, and staff-to-inmate ratio) on prison misconduct (total, violent, and non-violent misconduct and refusal to work) were examined through descriptive analysis, graphical portrayal, bivariate correlations, and multivariate analysis using ARIMA (autoregressive integrated moving average) analysis. The results showed that all models can predict prison misconduct partially. Staff-to-inmate ratio was the most consistently significant predictor in this study. Occupancy rate and old age were also significantly related to several types of prison misconduct. Limitations and policy implications are discussed considering these results.

The first essay formulates a dynamic general equilibrium optimal control model of an energy crop as part of a country's planned resource use over a period of time. The model attempts to allocate consumption, production, and factors of production to achieve the country's sustainable development goal. A Cobb-Douglas specification is used for both utility and production functions in the model. We calibrate the model with Thailand data. The selected model is used to generate the stationary state solution and to simulate the optimal policy function and optimal time paths. Two methods are used: a linear approximation method and the Runke-Kutta reverse shooting method. The model provides numerical results that can be used as information for decision makers and stakeholders to devise an economic plan to achieve sustainable development goals. The second essay studies the effect of international trade and changes in labor supply, land supply, and the price of imported energy on energy crop production for bio fuel and food, as well as impacts on social welfare. We develop a dynamic general equilibrium model to describe two baseline scenarios, a closed economy and an open economy. We find that international trade increases welfare and decreases the energy price. Furthermore, resources are allocated to produce more food under the open economy scenario than the quantities produced under a closed economy assumption. An increase in labor supply and land supply result in an increase in social welfare. An increase in imported energy price leads to a welfare loss, higher energy production, and lower food production. The third essay develops a partial equilibrium econometric model to project the impacts of an increase in ethanol production on the Thai agriculture sector over the next ten years. The model is applied to three scenarios for analyzing the effect of government ethanol production targets. The results from the baseline model and scenario analysis indicate that an expansion in ethanol production will result in a significant increase in cassava production, price, and land use. The increase in cassava production will shift land use from maize and sugar cane, thus increasing in price of maize.

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The study of serial killer collaboration has received little attention in academia. While current explanatory theories of serial homicide can include subtypes of serial killers that operate alone, the study of collaborating serial killers has been neglected. In this paper, an integrated, explanatory theory of serial killer collaboration is proposed. The theory builds on concepts from social learning theory, the trauma control model, and relational self theory and aims to examine what interpersonal dynamics that characterize the partnerships of collaborating serial killers. Five cases of collaborating serial killers have been analyzed and compared with focus on individual life histories and how these are reflected in the interpersonal dynamics in serial killer collaboration. The study found that serial killer collaboration is fundamentally characterized by a mutual need for human connection and approval, and that sociocultural role expectations affect the interpersonal dynamics of collaborating serial killers in terms of dominance, victim-preference, victim-acquisition, and method of murder.

Syftet med studien är att undersöka betydelsen faktorer kopplade till schemaläggning har för upplevelse av delaktighet och inflytande. De faktorer som undersökts är schemaläggningssystem, organisatoriska aspekter, samarbete, och flexibilitet. De teorier som används är Job demand-control model, Social exchange theory och Structural empowerment theory. Det är en kvalitativ intervjustudie med fem informanter som jobbar hel- eller deltid inom äldrevård eller funktionshinderomsorg i Umeå kommun. Informanterna har tre olika schemasystem med det gemensamma att samtliga informanter får ge önskemål på hur de vill att deras schema för kommande schemaperiod ska se ut. Resultatet visar att informanterna upplever olika grad av delaktighet och inflytande i sitt schemaläggningssystem. Centralt schemastöd är den funktion som minskar upplevelsen av delaktighet och inflytande för majoriteten av informanterna. Ökad utbildning, avsatt tid för schemaläggning, stöd för att öka samarbete på arbetsplatsen och kontakt med Centralt schemastöd är faktorer som sammanfattningsvis föreslås kan öka de anställdas delaktighet och inflytande i schemaläggning.