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
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Item READING COMPREHENSION STRATEGY INSTRUCTION IN UPPER-ELEMENTARY CLASSROOMS WITH ENGLISH LANGUAGE LEARNERS: A STUDY OF PRACTICES AND OUTCOMES(2015) Doyle, Candice Briece; Silverman, Rebecca D; Special Education; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The goal of this study was to investigate the relationship between reading comprehension strategy instruction (explicit or skills-based) in general education settings and third through fifth grade students' reading comprehension outcomes. In addition, I was interested in whether relationships between instruction and outcomes differed for students from English only (EO) and English language learner (ELL) backgrounds. To address these goals I conducted a secondary data analysis of 59 Reading/Language Arts classroom observation transcripts. These represented observations of 19 teachers at three time points (fall, winter, spring). I analyzed transcripts by employing an iterative coding process including open, axial, and selective coding (Strauss & Corbin, 1990). I coded teacher talk at the utterance (Crookes, 1990) level for either explicit instruction (instruction that included all of the following: introduction, modeling, collaborative practice, guided practice, independent practice) or skills-based practice (teacher practice in which students were asked to apply a comprehension strategy absent of instruction of how to do so). In addition I coded for separate parts of the explicit instruction model (introduction, modeling, collaborative practice, guided practice, independent practice). Then, I quantitized (Tashakori & Tedlie, 1998) the instructional code data into average frequency counts across observations in order to conduct multiple regression analyses with student reading comprehension outcome measures. I found no statistically significant results related to the explicit instruction model (as a whole), or skills-based practice and students' outcomes. However, when analyzing separate parts of explicit instruction, results suggested that more guided practice was associated with higher scores on one outcome measure. In exploring interactions between language background and instructional codes, I found no differences in relationships between instructional codes and reading comprehension for EOs versus ELLs.Item Error Observation in Schizophrenia(2009) Mann-Wrobel, Monica Constance; Blanchard, Jack J.; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Despite the pervasive and impairing nature of social difficulties in schizophrenia, the causes of these problems are not fully understood. It has been suggested that problems with cognitive functioning contribute to the social deficits of schizophrenia. However, little is known about the neural mechanisms that underlie cognitive processes directly linked to social dysfunction in schizophrenia. Recent studies of the mirror neuron system have focused on the error-related negativity (ERN), a negatively-deflected event-related brain potential that is elicited following the commission of an erroneous response. This study examined ERN activity in schizophrenia patients and psychiatrically healthy controls during performance and observation of a confederate performing a computerized flanker task. The lateralized readiness potential (LRP) allowed for a direct comparison of brain activation reflecting response readiness verses error signaling. Correlations between ERN activity during flanker observation, social cognition (i.e., theory of mind), and community social functioning were explored. Finally, correlations between verbal memory, executive functioning, and social functioning were examined and social cognition was explored as a mediator between neurocognition and social functioning. Results indicated that controls produced a robust ERN during execution of the flanker task, whereas ERN activity among patients was comparatively attenuated in amplitude. During observation, there were no significant group differences and no identifiable observation ERN; however, there was greater negative activity following error than correct trials in this condition for all participants. LRP activity did not parallel that of the ERN, supporting the differentiation of motor activity and error-related processing during observation. The only significant correlation to emerge between ERN activity and social cognition and social functioning was between occupational status and execution ERN activity among controls only. Unexpectedly, neurocognition and social functioning were negatively correlated in the patient group. Expectedly, these variables were positively correlated among controls. Therefore, regression analyses were conducted separately by group; however, neither neurocognition nor social cognition predicted a significant proportion of the variance in social functioning. Despite limitations, this research is discussed as a starting point for integrating the study of psychophysiological activity with social behavior and functioning, particularly in a clinical population with pronounced social deficits.Item A DEEP X-RAY SURVEY OF THE LOCKMAN HOLE NORTHWEST(2005-08-26) Yang, Yuxuan; Mushotzky, Richard F; Astronomy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)I present the X-ray analysis of the Chandra Large Area Synoptic X-ray Survey (CLASXS) of the Lockman Hole Northwest field. The contiguous solid angle of the survey is about 0.4 sqr degree and the flux limits are 5x10^-16 erg/cm^2/s in the 0.4-2 keV band and 3x10^-15 erg/cm^2/s in the $2-8$~keV band. The survey bridges the gap between deep pencil beam surveys, and shallower, larger area surveys, allowing a better probe of the X-ray sources that contribute most of the 2--10 keV cosmic X-ray background. A total of 525 X-ray point sources and 4 extended sources have been found. The number counts, X-ray spectra evolution, X-ray variability of the X-ray sources are presented. We show 3 of the 4 extended sources are likely galaxy clusters or galaxy groups. We report the discovery of a gravitational lensing arc associated with one of these sources. I present the spatial correlation function analysis of non-stellar X-ray point sources in the CLASXS and Chandra Deep Field North (CDFN). I calculate both redshift-space and projected correlation functions in comoving coordinates.The correlation function for the CLASXS field over scales of 3 Mpc < s < 200 Mpc can be modeled as a power-law of the form xi(s)=(s/s_0)^{-gamma}, with gamma = 1.6^{+0.4}_{-0.3} and s_0 = 8.05^{+1.4}_{-1.5} Mpc. The redshift-space correlation function for CDFN on scales of 1 Mpc <s < 100 Mpc is found to have a similar correlation length, but a shallower slope. The real-space correlation functions are derived from the projected correlation functions. By comparing the real- and redshift-space correlation functions, we are able to estimate the redshift distortion parameter beta = 0.4 +/- 0.2 at an effective redshift z = 0.94. We found the clustering does not dependence significantly on X-ray color or luminosity. A mild evolution in the clustering amplitude is found, indicating a rapid increase of bias with redshift. The typical mass of the dark matter halo derived from the bias estimates show little change with redshift. The average halo mass is found to be log(M_{halo}/M_sun}) ~ 12.4.