Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

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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    HISTORICAL GRAPH DATA MANAGEMENT
    (2015) Khurana, Udayan; Deshpande, Amol; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Over the last decade, we have witnessed an increasing interest in temporal analysis of information networks such as social networks or citation networks. Finding temporal interaction patterns, visualizing the evolution of graph properties, or even simply comparing them across time, has proven to add significant value in reasoning over networks. However, because of the lack of underlying data management support, much of the work on large-scale graph analytics to date has largely focused on the study of static properties of graph snapshots. Unfortunately, a static view of interactions between entities is often an oversimplification of several complex phenomena like the spread of epidemics, information diffusion, formation of online communities, and so on. In the absence of appropriate support, an analyst today has to manually navigate the added temporal complexity of large evolving graphs, making the process cumbersome and ineffective. In this dissertation, I address the key challenges in storing, retrieving, and analyzing large historical graphs. In the first part, I present DeltaGraph, a novel, extensible, highly tunable, and distributed hierarchical index structure that enables compact recording of the historical information, and that supports efficient retrieval of historical graph snapshots. I present analytical models for estimating required storage space and snapshot retrieval times which aid in choosing the right parameters for a specific scenario. I also present optimizations such as partial materialization and columnar storage to speed up snapshot retrieval. In the second part, I present Temporal Graph Index that builds upon DeltaGraph to support version-centric retrieval such as a node’s 1-hop neighborhood history, along with snapshot reconstruction. It provides high scalability, employing careful partitioning, distribution, and replication strategies that effectively deal with temporal and topological skew, typical of temporal graph datasets. In the last part of the dissertation, I present Temporal Graph Analysis Framework that enables analysts to effectively express a variety of complex historical graph analysis tasks using a set of novel temporal graph operators and to execute them in an efficient and scalable manner on a cloud. My proposed solutions are engineered in the form of a framework called the Historical Graph Store, designed to facilitate a wide variety of large-scale historical graph analysis.
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    String Quartet
    (2012) Polasky, Jacob Abraham; Moss, Lawrence; Music; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This is a String Quartet in three movements. It is an example of the use of set theory and combinatorial analysis in music composition. Harmony is created by the combination of four-tone sets into eight-tone sets. Contrapuntal devices, such as the arrangement of set elements to create maximum intervallic variety are explored in the second movement. This movement is also the focus of a complex pattern based on eight tone sets. Five of the tones are used regularly, while the other three tones are used to disrupt a sense of regularity.
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    A PILOT STUDY TO DEVELOP DISCOURSE CODES SPECIFIC TO PREFRONTAL DYSFUNCTION
    (2004-08-12) Eshel, Inbal; Ratner, Nan B.; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This pilot study developed a set of codes designed to capture the "nonaphasic" but characteristic discourse deficits that may be present following prefrontal cortex damage (PFCD). The codes were utilized based on narrative sample elicitation to investigate between-group differences in two study populations: patients with left, right, or bi-frontal PFCD and age and education-matched healthy comparison group participants. Narrative samples were coded on indices of content units, thematic units, story grammar features, and discourse errors, and analyzed using CLAN. Results of this study support the original deficit hypotheses. The coding schema demonstrated fair to good inter-rater reliability, stronger performances by the healthy comparison group across all four levels of analysis, and poorer performance overall on the retell phase than the tell phase. Qualitative analysis revealed relatively few discourse errors associated with the healthy comparison group, while various classic discourse errors were associated with the PFCD group.