Theses and Dissertations from UMD
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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 give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Context and the Conceptual Building Blocks for Synthesis in the Literature Reviewing Process(2020) Morabito, John; Chan, Joel; Master in Information Management; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Conducting a literature review involves trying to capture knowledge in such a way that it can be reused during synthesis and writing and this can be a challenge. We set out to describe the information capture process with the goal of identifying patterns which could influence the design of software that would support the literature reviewing process. We conducted a qualitative user study of four participants with a protocol analysis of the information capture portion of their literature reviewing process, focusing on a detailed description of how they captured contextual information in their notes and annotations, and how this varied across tools used. Our analysis revealed three common patterns of context capture, and quantitative and qualitative differences in these patterns across tools for literature reviewing. These findings provide insights for system design to support information capture in literature reviewing systems.Item Modeling Deep Context in Spatial and Temporal Domain(2018) Dai, Xiyang; Davis, Larry S.; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Context has been one of the most important aspects in computer vision researches because it provides useful guidance to solve variant tasks in both spatial and temporal domain. As the recent rise of deep learning methods, deep networks have shown impressive performances on many computer vision tasks. Model deep context explicitly and implicitly in deep networks can further boost the effectiveness and efficiency of deep models. In spatial domain, implicitly model context can be useful to learn discriminative texture representations. We present an effective deep fusion architecture to capture both the second order and first older statistics of texture features; Meanwhile, explicitly model context can also be important to challenging task such as fine-grained classification. We then present a deep multi-task network that explicitly captures geometry constraints by simultaneously conducting fine-grained classification and key-point localization. In temporal domain, explicitly model context can be crucial to activity recognition and localization. We present a temporal context network to explicitly capture relative context around a proposal, which samples two temporal scales pair-wisely for precise temporal localization of human activities; Meanwhile, implicitly model context can lead to better network architecture for video applications. We then present a temporal aggregation network that learns a deep hierarchical representation for capturing temporal consistency. Finally, we conduct research on jointly modeling context in both spatial and temporal domain for human action understanding, which requires to predict where, when and what a human action happens in a crowd scene. We present a decoupled framework that has dedicated branches for spatial localization and temporal recognition. Contexts in spatial and temporal branches are modeled explicitly and fused together later to generate final predictions.Item FINDING OBJECTS IN COMPLEX SCENES(2018) Sun, Jin; Jacobs, David; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Object detection is one of the fundamental problems in computer vision that has great practical impact. Current object detectors work well under certain con- ditions. However, challenges arise when scenes become more complex. Scenes are often cluttered and object detectors trained on Internet collected data fail when there are large variations in objects’ appearance. We believe the key to tackle those challenges is to understand the rich context of objects in scenes, which includes: the appearance variations of an object due to viewpoint and lighting condition changes; the relationships between objects and their typical environment; and the composition of multiple objects in the same scene. This dissertation aims to study the complexity of scenes from those aspects. To facilitate collecting training data with large variations, we design a novel user interface, ARLabeler, utilizing the power of Augmented Reality (AR) devices. Instead of labeling images from the Internet passively, we put an observer in the real world with full control over the scene complexities. Users walk around freely and observe objects from multiple angles. Lighting can be adjusted. Objects can be added and/or removed to the scene to create rich compositions. Our tool opens new possibilities to prepare data for complex scenes. We also study challenges in deploying object detectors in real world scenes: detecting curb ramps in street view images. A system, Tohme, is proposed to combine detection results from detectors and human crowdsourcing verifications. One core component is a meta-classifier that estimates the complexity of a scene and assigns it to human (accurate but costly) or computer (low cost but error-prone) accordingly. One of the insights from Tohme is that context is crucial in detecting objects. To understand the complex relationship between objects and their environment, we propose a standalone context model that predicts where an object can occur in an image. By combining this model with object detection, it can find regions where an object is missing. It can also be used to find out-of-context objects. To take a step beyond single object based detections, we explicitly model the geometrical relationships between groups of objects and use the layout information to represent scenes as a whole. We show that such a strategy is useful in retrieving indoor furniture scenes with natural language inputs.Item EFFECTS OF REWARD CONTEXT ON FEEDBACK PROCESSING AS INDEXED BY TIME-FREQUENCY ANALYSIS(2016) Massey, Adreanna; Bernat, Edward; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The role of reward context has been investigated as an important factor in feedback processing. Previous work has demonstrated that the amplitude of the feedback negativity (FN) depends on the value of the outcome relative to the range of possible outcomes in a given context, not the objective value of the outcome. However, some research has shown that the FN does not scale with loss magnitude in loss-only contexts, suggesting that some contexts do not show a pattern of context-dependence. Time-frequency decomposition techniques have proven useful for isolating important activity, and have shown that time-domain ERPs can be better represented as separable processes in delta (0-3 Hz) and theta (3-7 Hz). Thus, the current study seeks to assess whether the role of context in feedback processing is better elucidated using time-frequency analysis. Results revealed that theta was more context-dependent and showed a binary response to best-worst differences in the gain and even contexts. Delta was more context-independent: the best outcomes scaled linearly with reward magnitude and best-worst differences scaled with context valence. Our findings reveal that theta and delta are differentially sensitive to context and that context valence may play a critical role in determining how the brain processes good and bad outcomes.Item FROM SOUND TO MEANING: QUANTIFYING CONTEXTUAL EFFECTS IN RESOLUTION OF L2 PHONOLEXICAL AMBIGUITY(2014) Lukianchenko, Anna; Gor, Kira; Second Language Acquisition and Application; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In order to comprehend speech, listeners have to combine low-level phonetic information about the incoming auditory signal with higher-order contextual information. Unlike native listeners, nonnative listeners perceive speech sounds through the prism of their native language, which sometimes results in perceptual ambiguity in their second language. Across four experiments, both behavioral and electrophysiological, this dissertation provides evidence that such perceptual ambiguity causes words to become temporarily indistinguishable. To comprehend meaning, nonnative listeners disambiguate words through accessing their semantic, syntactic and morphological characteristics. Syntactic and semantic cues produce a stronger context effect than morphological cues in both native and nonnative groups. Thus, although nonnative representations may differ in that they may lack phonological specification, the mechanisms associated with the use of higher-order contextual information for meaning resolution in auditory sentence comprehension are essentially the same in the native and nonnative languagesItem The Unique Political Attitudes and Behaviors of Individuals in Aged Communities(2012) Bramlett, Brittany H.; Gimpel, James G; Government and Politics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation examines the political attitudes and behaviors of individuals residing in communities with large proportions of older adults. These types of locations are growing in number in the United States as the Baby Boomer Generation arrives at retirement age. Many scholars and journalists rely on theories of `senior power' and predict that the places with large numbers of senior citizens should be especially politically powerful. However, many studies have provided little evidence to support these claims. I explore the old questions with updated data, methods and approaches--theorizing that older adults living among their elderly peers will, in fact, exhibit unique levels of political knowledge, efficacy, and participation as well as hold distinct attitudes for safety net issues. Using large-scale surveys and multilevel modeling techniques, I find that older adults residing in aged communities display higher levels of political knowledge than their elderly peers living in places without the same aged context. However, they are less politically efficacious and somewhat less likely to vote. Older adults living among their peers are also more likely to support social welfare programs, controlling for party identification. I also examine the contextual effect of the aged context for younger residents. In particular, I find that young people are also quite supportive of the safety net policies, which provide assistance for their elder neighbors. Because of this support from the younger generation, older adults in aged communities may rarely, if ever, face threats to their livelihood, driving them into political action. Taken together, the results from this dissertation show that older adults living amongst their peers are certainly equipped for intense political engagement or senior power--but they choose political retreatism rather than activism.Item Information Seeking in Context: Teachers' Content Selection during Lesson Planning Using the Shoah Foundation's Visual History Archive of Holocaust Survivor Testimony(2011) Lawley, Kathryn Newton; Soergel, Dagobert; Library & Information Services; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study explored the information seeking task of content selection. An integrative conceptual framework used existing models to examine the context and process of information seeking, evaluation, and selection. The conceptual framework incorporated three main elements of the information seeking process: * The information need context, * The information search process, * Relevance criteria. Among teachers' many duties are the creation, implementation, and revision of lesson plans. A subtask of lesson planning is content selection, which occurs when teachers seek outside content, such as readings or audio recordings, to incorporate into lesson plans. Content selection is seen here as a work-task-embedded information seeking process. A qualitative study was implemented within the setting of a week-long professional development workshop, during which eight teachers used a custom software product that combined a lesson-planning module with an information retrieval (IR) system. The IR system provided access to a subset of the Shoah Foundation's Visual History Archive. Data types included interviews, fly-on-the-wall transcripts, transaction logs, relevance judgments, and lesson plans. Analysis combined inductive and deductive techniques, including start codes, constant comparison, emergent themes, and matrix analysis. Findings depict associations among each component of the framework. 1. The information need context consists of five layers (Environment, Role, Person, Task, Information Source), each of which influences information search and relevance. 2. The ISP includes two cognitive-behavioral facets: Conceptualizing and Actualizing. 3. Relevance criteria are the situationally-driven embodiment of contextual elements that apply to information seeking. These findings have theoretical and practical implications for information studies and education. For information studies, this study contributes to understanding of the ISP as contextual, cognitive, and interactive. Information need, while unobservable in its native form, can be depicted in enough detail to supply meaningful requirements for the design of information systems and processes. Content selection is a form of exploratory search, and this study's implications suggest that the "traditional" reference interview should be used as an interaction model during exploratory search. For education, this study extends the discourse about consequences of standards-based education for teacher practice and contributes to models of teacher planning as an iterative, cognitive process.Item Resurrecting an Old Place with a New Purpose(2008) Schneller, Martiena L.; Hurtt, Steven W; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis will be based on the environs of Petersburger Strasse, in East Berlin, Germany; the cluttered street and underutilized surroundings will be reinvented, by providing refurbished housing with mixed use ground floors all catering to the general public as well as the young entrepreneurs and artists of the neighborhood. Directly adjacent to House 68, my thesis project, a cultural center composed of both restored and new buildings will be located facing the nearby community park, providing galleries and flexible spaces for art performances, classes, public gatherings, all while reinforcing a place of importance and identity in the community. This thesis contends that an architectural expression, pulling from regional traditions, can heal a scarred environment; providing a sense of community while acting as a catalyst for future cultural traditions that can point the way to a more sustainable future.