UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item A Survey of Bees in the University of Maryland Campus Area(2021) Striegel, Theodore; Hawthorne, David; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)I sampled the wild bee community in the University of Maryland campus area in College Park, Maryland for one season and combined those data with that from previous years. The protocol was modified to significantly expand the geographic scope of the survey, covering a much wider spatial range of the campus. This combined data was used to assess population trends, best practices, and determine whether or not the expanded protocol offers advantages in capturing local wild bee diversity and/or analytical benefits over the previous survey. New data allowed for characterization of the local wild bee community and discerned a landscape driver of spatial variance in local diversity. Appropriateness of different geographic parameters was found to depend on survey goals.Item Adaptive Coping in African American Adolescents: The Role of Mother-Adolescent Relationship Quality, Parental Monitoring, and Racial Socialization(2018) Greene, Diamond; Smith-Bynum, Mia A; Family Studies; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Adolescence can be a stressful stage of development for adolescents and their families; however, it is particularly stressful for African American adolescents who also have to deal with additional stressors such as racial discrimination, which can be detrimental to one’s mental health. The purpose of this study is to examine how: (a) adolescents’ perception of mother-adolescent relationship quality, (b) adolescents’ perception of parental monitoring from their parents, and (c) adolescents’ perception of racial socialization (e.g., cultural coping with antagonism) messages, predicts adaptive coping strategies. The sample included 111 African American adolescents (55% female), ranging from ages 14 to 17 (mean age = 15.50), residing in the Washington, DC metropolitan area between 2010 and 2011. The median household income for this sample is $60,000-69,999. Results showed that adolescents’ perception of positive mother-adolescent relationship quality and receiving racial socialization messages, specifically cultural coping with antagonism messages, were significant predictors of adaptive coping.Item PREDICTION IN SOCIAL MEDIA FOR MONITORING AND RECOMMENDATION(2012) Wu, Shanchan; Raschid, Louiqa; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Social media including blogs and microblogs provide a rich window into user online activity. Monitoring social media datasets can be expensive due to the scale and inherent noise in such data streams. Monitoring and prediction can provide significant benefit for many applications including brand monitoring and making recommendations. Consider a focal topic and posts on multiple blog channels on this topic. Being able to target a few potentially influential blog channels which will contain relevant posts is valuable. Once these channels have been identified, a user can proactively join the conversation themselves to encourage positive word-of-mouth and to mitigate negative word-of-mouth. Links between different blog channels, and retweets and mentions between different microblog users, are a proxy of information flow and influence. When trying to monitor where information will flow and who will be influenced by a focal user, it is valuable to predict future links, retweets and mentions. Predictions of users who will post on a focal topic or who will be influenced by a focal user can yield valuable recommendations. In this thesis we address the problem of prediction in social media to select social media channels for monitoring and recommendation. Our analysis focuses on individual authors and linkers. We address a series of prediction problems including future author prediction problem and future link prediction problem in the blogosphere, as well as prediction in microblogs such as twitter. For the future author prediction in the blogosphere, where there are network properties and content properties, we develop prediction methods inspired by information retrieval approaches that use historical posts in the blog channel for prediction. We also train a ranking support vector machine (SVM) to solve the problem, considering both network properties and content properties. We identify a number of features which have impact on prediction accuracy. For the future link prediction in the blogosphere, we compare multiple link prediction methods, and show that our proposed solution which combines the network properties of the blog with content properties does better than methods which examine network properties or content properties in isolation. Most of the previous work has only looked at either one or the other. For the prediction in microblogs, where there are follower network, retweet network, and mention network, we propose a prediction model to utilize the hybrid network for prediction. In this model, we define a potential function that reflects the likelihood of a candidate user having a specific type of link to a focal user in the future and identify an optimization problem by the principle of maximum likelihood to determine the parameters in the model. We propose different approximate approaches based on the prediction model. Our approaches are demonstrated to outperform the baseline methods which only consider one network or utilize hybrid networks in a naive way. The prediction model can be applied to other similar problems where hybrid networks exist.Item A Hybrid Testing Platform for Realistic Characterization of Infrastructure Sensor Technology(2011) Mercado, Michael William; Zhang, Yunfeng; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In America's transportation infrastructure, maintaining safe and serviceable bridges is of paramount importance to America's transportation officials. In order to meet the increasing demands for information-based maintenance and repair of civil infrastructures such as highway bridges, an increasing number of structural health monitoring sensors and other non-destructive evaluation (NDE) devices have begun to be implemented on these structures. Before these health monitoring sensors can be implemented on a large scale, they must first be validated and characterized in a controlled environment. This thesis proposes and demonstrates the use of a hybrid testing platform to create a more realistic testbed to evaluate these structural health monitoring sensors for steel bridges. The details of this hybrid testing platform are discussed including the effects of ramp time, stress level, complexity of the virtual model, fatigue, and high temperature testing. The accuracy and practical implementation of this hybrid testing platform are also addressed.Item Parenting and Delinquency: An Exploration of Gender Effects(2006-12-11) Wilkins, Lynda; Gottfredson, Denise; Criminology and Criminal Justice; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In the search for the causes and correlates of juvenile delinquency, parenting has historically been recognized as one of the primary contributing or inhibiting factors to delinquent behaviors. The current study focuses on the relationship between the specific parenting practices of monitoring and attachment, and the delinquent behaviors of both males and female children, in the preadolescent ages of 7-11. This study finds that while parents monitor male and female children equally, parents report a higher level of attachment to their male children. Additionally, although most of the measures of parenting have similar impacts for male and female children, there are certain practices which produce divergent results based upon the child's gender. Parental reports of monitoring are a stronger inhibitor of intentions to use illicit substances for males, while the parent's attachment is a greater inhibitor of self-reported rebellious behavior for females. These results have implications for future research and program design.Item Stream restoration in the Chesapeake Bay watershed: Data synthesis and analysis of interviews with practitioners(2006-05-08) Hassett, Brooke A.; Palmer, Margaret A; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Chesapeake Bay is the focus of a high profile restoration program and river restoration is one part of the strategy. A comprehensive database of over 4700 stream restoration projects across the watershed was compiled to examine where money is spent, what issues motivate restoration, and what approaches are used. The majority of projects were implemented to restore riparian vegetation and improve water quality. While over $400 million has been spent on stream restoration projects since 1990, less than 6% of written project records indicated that related monitoring had occurred. Comprehensive interviews with project managers were conducted for a subsample projects to characterize patterns in project goals, design, expenditures, project evaluation, and project success. Interviewed practitioners reported that the majority of projects were initiated to address environmental degradation, 70% were linked to other projects within the same watershed, and 76% of projects had some form of associated monitoring.Item Monitoring land degradation in Southern Africa by assessing changes in primary productivity.(2005-06-15) Wessels, Konrad; Prince, Stephen D.; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Land degradation is one of the most serious environmental problems of our time. Land degradation describes circumstances of reduced biological productivity. The fundamental goal of this thesis was to develop land degradation monitoring approaches based on remotely sensed estimates of vegetation production, which are capable of distinguishing human impacts from the effects of natural climatic and spatial variability. Communal homelands in South Africa (SA) are widely regarded to be severely degraded and the existence adjacent, non-degraded areas with the same soils and climate, provides a unique opportunity to test regional land degradation monitoring methods. The relationship between 1km AVHRR, growth season sumNDVI and herbaceous biomass measurements (1989-2003) was firstly tested in Kruger National Park, SA. The relationship was moderately strong, but weaker than expected. This was attributed to the fact that the small areas sampled at field sites were not representative of the spatial variability within 1x1km. The sumNDVI adequately estimated inter-annual changes in vegetation production and should therefore be useful for monitoring land degradation. Degraded areas mapped by the National-Land-Cover in north-eastern SA were compared to non-degraded areas in the same land capability units. The sumNDVI of the degraded areas was consistently lower, regardless of large variations in rainfall. However, the ecological stability and resilience of the degraded areas, as measured by the annual deviations from each pixel's mean sumNDVI, were no different to those of non-degraded areas. This suggests that the degraded areas may be in an alternative, but stable ecological state. To monitor human-induced land degradation it is essential to control for the effects of rainfall on vegetation production. Two methods were tested (i) Rain-Use Efficiency (RUE=NPP/Rainfall) and (ii) negative trends in the differences between the observed sumNDVI and the sumNDVI predicted by the rainfall using regressions calculated for each pixel (RESTREND). RUE had a strong negative correlation with rainfall and did not provide a reliable index of degradation. The RESTREND method identified areas in and around the degraded communal lands that exhibit negative trends in production per unit rainfall. This research made a significant contribution to the development of remote sensing based land degradation monitoring methods.