Correctness and Progress Verification of Non-Blocking Programs

The progression of multi-core processors has inspired the development of concurrency libraries that guarantee safety and liveness properties of multiprocessor applications. The difficulty of reasoning about safety and liveness properties in a concurrent environment has led to the development of tools to verify that a concurrent data structure meets a correctness condition or progress guarantee. However, these tools possess shortcomings regarding the ability to verify a composition of data structure operations. Additionally, verification techniques for transactional memory evaluate correctness based on low-level read/write histories, which is not applicable to transactional data structures that use a high-level semantic conflict detection. In my dissertation, I present tools for checking the correctness of multiprocessor programs that overcome the limitations of previous correctness verification techniques. Correctness Condition Specification (CCSpec) is the first tool that automatically checks the correctness of a composition of concurrent multi-container operations performed in a non-atomic manner. Transactional Correctness tool for Abstract Data Types (TxC-ADT) is the first tool that can check the correctness of transactional data structures. TxC-ADT elevates the standard definitions of transactional correctness to be in terms of an abstract data type, an essential aspect for checking correctness of transactions that synchronize only for high-level semantic conflicts. Many practical concurrent data structures, transactional data structures, and algorithms to facilitate non-blocking programming all incorporate helping schemes to ensure that an operation comprising multiple atomic steps is completed according to the progress guarantee. The helping scheme introduces additional interference by the active threads in the system to achieve the designed progress guarantee. Previous progress verification techniques do not accommodate loops whose termination is dependent on complex behaviors of the interfering threads, making these approaches unsuitable. My dissertation presents the first progress verification technique for non-blocking algorithms that are dependent on descriptor-based helping mechanisms

Representing Uncertainty: Beliefs and Habits in the International Development Evaluation Context

Evaluation can be imagined as an uncertainty management strategy and evaluators as a class of professionals whose role is reducing uncertainty for decision-makers. In the development sector, uncertainty about the efficacy of various interventions exists and evaluations are needed to improve organizational resource utilization. Representations of uncertainty impact decision-making. Evaluator beliefs and routines regarding uncertainty representation in evaluation reports contribute to the ability of evaluation to influence decisions about development programs and policies. This study aimed to explore these beliefs and habits and to understand how they are influenced by the evaluation context. Social Representations Theory is used to situate evaluator beliefs and habits within an evaluation context and explain how these beliefs and habits form. Data were collected from 196 evaluators working in the international development context via an online survey. Results indicate that evaluators are generally uncertainty-oriented people who believe uncertainty should be represented in evaluation reports. However, a gap between their beliefs and habits was identified. Latent profile analysis suggests the existence of two groups of evaluators. The majority of evaluators fall within a “Conventional Uncertainty Representing Evaluators” group, with a small minority of “Heterodox Uncertainty Representing Evaluators” exhibiting above average beliefs and habits. Evaluator Uncertainty Representing group membership is significantly predicted by organizational uncertainty management styles after controlling for evaluator experience and education. Organizational uncertainty management styles are also significantly associated with the beliefs-habits gap. Answers to the research questions in this study provide initial support for an evaluation context model in which evaluator habits and beliefs about uncertainty in the evaluation context are not only being shaped by the organizational context, but also shaping the organizational context. I argue that these findings suggest social representations about uncertainty that exist within particular organizational contexts explain the existence of a conventional majority and a heterodox minority of evaluator beliefs and habits and that evaluators working within these contexts reinforce such beliefs and habits among new colleagues

Impact of Peer Evaluation Confidentiality on Student Marks

Although group work is commonly used in university-level instruction, social loafing, domineering team members, poor attenders, and inequitable distribution of marks have been identified as obstacles to team-based learning. Peer evaluation has been proposed as one vehicle to address these issues. For use in grading, peer evaluations are often anonymous; however, as tools to address team functioning, they should not be conducted anonymously, but rather with the results discussed as feedback. It has been suggested, however, that non-confidential peer evaluations will artificially elevate students’ marks. In this study, we investigated the impact of peer evaluation confidentiality on students’ marks. Without a weighted correction, confidential evaluations significantly dropped students’ marks while non-confidential evaluations raised them. Implications for practice are discussed

Wilderness State Park Volunteers: A Qualitative Case Study of Meaning and Sustainability

In an increasingly urbanized world, parks, open space and wilderness areas are vitally important to human well-being. California State Parks provide people with the ability to connect with nature and engage in outdoor recreation. Moreover, these parks protect natural and cultural resources and preserve biodiversity. California State Parks are underfunded and rely on volunteers to support essential park services. The Wilderness State Park Uniformed Volunteer Program provides essential recreation, resource protection, and biodiversity services. In order to determine the elements of the volunteering experience that contribute to a strong sense of volunteer identity and meaning, a qualitative case study was conducted using semi-structured interviews and grounded theory analysis. Results show that three themes emerge as providing a strong sense of meaning for volunteers: connecting with nature, working together, and helping others. Volunteers in this study demonstrated that they construct deep meaning around their volunteer experiences and foster an environmental stewardship identity within a framework of shared values, significance, goal-orientation, and belonging. This study has implications for volunteer satisfaction and retention as well as for overall sustainability of the parks’ mission

Pathways to Empowerment in Substance Abuse Prevention: Citizen Participation, Sense of Community, and Police Responsiveness in an Urban U.S. Setting

Community-based substance abuse prevention initiatives often rely on the empowerment of community residents. Few studies, however, have examined predictors of empowerment in substance abuse prevention contexts. This study tested a path model that included two environment-related variables (i.e., residents’ awareness of community substance abuse problems and perceived incivilities in their community), two variables representing residents’ perceptions of their community (i.e., sense of community and perceived police responsiveness to drug crime) and citizen participation as predictors of the intrapersonal component of psychological empowerment. The model was found to provide a good fit to the data from a random sample of urban residents (n=283) who participated in an evaluation of a National Institute of Justice community policing initiative in the Southwestern United States. Findings suggest that empowerment-based interventions aimed at preventing substance abuse and its related harmful consequences should incorporate activities that specifically address sense of community and police responsiveness to drug crime. Limitations and directions for future research are discussed