University of Maryland, Baltimore County
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Data-driven group analysis of complex-valued fMRI data
No full textAnalysis of functional magnetic resonance imaging (fMRI) data in its native, complex form has been shown to increase the sensitivity of the analysis both for data-driven techniques such as independent component analysis (ICA) and for model-driven techniques. The promise of an increase in sensitivity and specificity in clinical studies provides a powerful motivation for utilizing both the phase and magnitude data; however, the unknown and noisy nature of the phase poses a challenge for successful study of the fMRI data. In addition, complex-valued analysis algorithms, such as ICA, suffer from an inherent phase ambiguity, which introduces additional difficulty for group analysis and visualization of the results. We present solutions for these issues, which have been among the main reasons phase information has been traditionally discarded, and show their effectiveness when used as part of a complex-valued group ICA algorithm application. The developed methods become key components of a framework that allows the development of new fully complex data-driven and semi-blind methods to process, analyze, and visualize fMRI data. In this dissertation, we first introduce the methods developed as part of the fully complex framework for ICA of fMRI data. We introduce a physiologically motivated de-noising method that uses phase quality maps to successfully identify and eliminate noisy voxels--3D pixels--in the fMRI complex images so they can be used in individual and group studies. We also introduce a phase correction scheme that can be either applied sub-sequent to ICA of fMRI data or can be incorporated into the ICA algorithm in the form of prior information to eliminate the need for further processing for phase correction. Finally, we present two visualization methods that are used to augment the sensitivity and specificity in the detection of activated voxels. We show the benefits of using the developed methods on actual complex-valued fMRI data. In the remainder of the dissertation, we focus on developing constrained ICA (C-ICA) algorithms for complex-valued fMRI data. C-ICA uses prior information, hence providing a balance between model-based and data-driven approaches such as ICA to improve the source estimation performance and robustness to noise. C-ICA algorithms have been used to improve the estimation performance in real-valued fMRI data, but--to our knowledge--have not been applied to complex-valued fMRI data. We develop the first C-ICA algorithm that uses complex-valued references to constrain either the sources or the mixing coefficients. The designed algorithm is not restricted to having a unitary demixing matrix, which is a major assumption in existing C-ICA algorithms. We show, on both simulated and actual fMRI data, how the performance of ICA improves by using prior information about the fMRI paradigm
CRANK THAT BASS: IS RADIO RAP PERPETUATIG THE IDEALS OF INEQUALITY AMONGST COLLEGIATE MALES?
No full textThe rap music that is played on mainstream radio is currently laden with conspicuous consumption, negative portrayals of masculinity, and misogyny. These three themes are vehicles for stratification and inequality that could be potentially embedded into the psyche of all who listen to rap music on the radio. The purpose of this research is to see if listening to commercial rap music, with its pervasive themes perpetuating inequality, have impacted undergraduate collegiate males', who attend a mid-Atlantic research university, self esteem and or sentiments towards women. The research was conducted using a mixed methods procedure, featuring a content analysis of commercial rap music, an online survey (N = 168), and in person qualitative interviews (N = 5). The results of this study can be used in future studies concerning commercial rap music
Fabrication and Characterization of a Pd Nanowire-based Glucose Biofuel Cell
No full textThe use of glucose as a source in biofuel cell technology has received a lot of attention in part due to the potential applications of such systems. In addition to the being a clean energy alternative, it provides a pathway for implantable microelectronic devices, such as pacemakers, to be powered by interstitial fluid and eliminate the need for batteries. Furthermore, using interstitial fluid as fuel sources will drastically reduce necessary invasive surgeries to replace batteries. Additionally, cost to such patients will be reduced while quality of life enhanced. The research presents a unique platform for harvesting energy from glucose. Using semiconductor cleanroom techniques, electrically conductive palladium nanowires are grown on anodized aluminum oxide templates using silicon and glass as supporting substrates. Photolithography is used to create two non-continuous gold windows and contact pads on the substrates. AAO templates are attached to the two gold windows and palladium nanowires are electrochemically grown on the AAO templates. Glucose oxidase and catalase are immobilized on the anode and laccase on the cathode. In the presence of glucose, electrons are released that result in the generation of voltage and current. The current-voltage behavior of the fuel cell, as well as electrochemical properties, is characterized using standard performance metrics. In 5 mM glucose solution with a neutral pH of 7.3, the open circuit voltage obtained was 335 mV and the short circuit current of 6 �A to yield a maximum power output of 1.38 �W
An Investigation into the Emotional and Behavioral Profiles of Youth At Risk for Psychosis using the Behavior Assessment System for Children, Second Edition
No full textInterest in predicting psychosis-risk, and psychopathology associated with risk, has grown exponentially as research has suggested a link between early intervention for psychosis and better outcomes. Researchers have identified the clinical high-risk (CHR) state as a means of identifying vulnerable individuals potentially at risk for psychosis. Although youth at CHR tend to be in need of mental health services, there is a current lack of understanding regarding the distress specifically associated with this state. Investigating various methods of assessing psychosis-specific symptoms as well as other psychosocial difficulties experienced by CHR individuals might serve to guide clinicians in the identification and treatment of this population. Within a help-seeking sample of 81 youth aged 12-22, and a subsample of 56 youth-caregiver dyads, the current study examined the types of distress associated with psychosis-risk symptoms using the Behavior Assessment System for Children, Second Edition (BASC-2). Additionally, parent and youth reports of BASC-2 atypicality, a construct designed to capture symptoms similar to those associated with the psychosis-risk, were evaluated against clinician-rated risk symptoms. Results indicated that CHR symptoms are associated with a broad range of symptoms that warrant further investigation. Findings also suggested that BASC-2 atypicality (as reported by youth and parents) may be particularly useful for the assessment of CHR symptoms, as this construct appears to be predictive of clinician-rated risk. Given this evidence for convergent validity between atypicality and risk symptoms, as well as the additional clinical information the full measure affords, the BASC-2 may be a promising tool for psychosis-risk screening
Recent divergence in the Orchard Oriole complex: using molecular genetics and vocalizations to examine species boundaries
No full textUnderstanding species boundaries and the process of speciation is a fundamental part of understanding the biodiversity of the world around us. Studies of recently diverged/diverging species can be used to examine species boundaries to better understand the nature of species/speciation. Orchard Oriole (Icterus spurius) and Fuertes' Oriole (I. fuertesi) are sister taxa with different breeding grounds and different adult plumage coloration, yet their mtDNA are intermixed, indicating a possible recent divergence event. I compared the molecular genetics (mtDNA and nuDNA) of both taxa and found that I. spurius and I. fuertesi are in the earliest stages of speciation - at a point where most neutral markers within their nuclear DNA do not yet reflect their divergence. As birdsong has the capability of diverging rapidly as two taxa speciate, I looked for evidence of divergence in the songs and jeet alarm calls of the two taxa. My analyses failed to find fixed song differences, yet the jeet calls show differentiation in a number of acoustic characteristics, such as in call duration and number of parts of the call. These differences may reflect ecological adaptation or divergence due to stochastic processes acting independently in these two taxa - indicating a degree of divergence between them. To test whether adult males were able to cue into subtle song variations that were not captured by the quantitative analyses, I conducted playback experiments on male I. spurius in Maryland - exposing focal males to homotypic songs (I. spurius), I. fuertesi songs and the songs of a negative control (I. galbula). Focal males in these experiments reacted to both conspecific and I. fuertesi songs - indicating they are identifying I. fuertesi as a potential sexual competitor. Thus, songs have not yet diverged enough that males no longer identify the other taxon's songs as potential sexual competition. However, there is some evidence that males respond more weakly to I. fuertesi songs. Regardless, song is likely not acting as a strong barrier to gene flow between these taxa. This study indicates that these two taxa are likely in the earliest stages of speciation, making them a model system to understand the process of speciation
Two Gentlemen of Verona (2012)
No full textPromotional materials produced for Two Gentlemen of Verona, performed by the UMBC Theatre Department in April 2013. Includes play bill, program, and ten publicity photographs.April 18-April 27, 201
