Quantum dislocations in solid Helium-4
Year of Dissertation:
2012
In this thesis the following problems on properties of solid 4He are considered: i) the role of long-range interactions in suppression of dislocation roughening at T = 0; ii) the combined effect of 3He impurities and Peierls potential on shear modulus softening; iii) the dislocation superclimb and its connection to the phenomenon of “giant isochoric compressibility” ; iv) non-linear dislocation response to the applied stress and stress-induces dislocation roughening as a I-order phase transition in 1D at finite temperature.
Neural Effects of Exposure to the Environmental Chemical, Bisphenol A, During Development
Year of Dissertation:
2010
Exposure to Bisphenol A (BPA), an environmental chemical, has been linked to changes in physiology, neural development, and behavior. The focus of this study was to determine the effects of BPA exposure, during a short developmental window, on physiology, activity, anxiety, cognition, and neurochemistry. In prenatal study, dams were administered 100 mcg/kg/day orally, from gestational day 16 to parturition. Postnatal study pups received subcutaneous injection of 60 or 100 mcg/kg BPA from postnatal day 0 to 6. All pups were weighed, examined for evidence of vaginal opening, and, at adulthood, performed behavioral tasks measuring locomotor activity, anxiety, and visual and spatial memory. Brain monoamines were measured using high performance liquid chromatography in the postnatal group. Prenatal BPA contributed to low juvenile body weight in both sexes and adult overweight in male subjects. Hyperactivity and memory deficits were observed in both sexes of BPA treated subjects. Postnatal 100 mcg/kg BPA females experienced delayed vaginal opening, less anxiety behavior in elevated plus maze, and spatial memory impairments. BPA treated subjects of both sexes had increased norepinephrine and dopamine turnover in basolateral amygdala and hippocampus, areas which are implicated in anxiety and cognition, respectively. The data suggests that BPA exposure during perinatal life causes disruptions in physiology, behavior, memory and neurochemistry that persist to adulthood. In addition, postnatal effects of BPA may be mediated by alterations in central monoaminergic function.
Factitious Virtue
Year of Dissertation:
2011
The primary aim of this project is to argue that empirical challenges to moral theories like virtue ethics should be co-opted rather than resisted. Virtue ethics has much to offer. Its vision of a flourishing life seems a better object of moral contemplation and evaluation than the sometimes dry rules of deontology and consequentialism; its focus on "thick" concepts like honesty and courage seems to bridge the is/ought gap; its weaving together of reasons and motivations obviates concerns about moral schizophrenia. Furthermore, the virtue ethical account of action paints a detailed picture of sensitivity to reasons, careful and correct construal of ambiguous information, and thoughtful deliberation.
Does Discovery-Based Instruction Enhance Learning?
Year of Dissertation:
2010
Since Bruner's (1961) call for research into discovery-based learning, controversy has surrounded the efficacy of such a constructivist approach to instruction (e.g., Tobias & Duffy, 2009). For decades, research has investigated to what extent discovery-based instruction enhances learning tasks or conversely, detracts from them. Research has included wide varieties of domains and discovery-based instructional approaches. Samples have included both children and adults and both novices and experts within their specific domains. It seems that what the field needs is a definition of discovery learning from a practical perspective because a review of the literature reveals that although there might be an implied sense of what discovery learning is, the methodologies employed vary greatly. Furthermore, the characteristics of effective discovery methodology(s) need to be examined with careful consideration of the domain involved, the age of the sample, the comparison condition, and the outcome assessments. Therefore, two meta-analyses were conducted using a sample of 164 studies: the first examined the effects of unassisted discovery learning versus explicit instruction and the second examined the effects of enhanced and/or assisted discovery versus other types of instruction (e.g., explicit, unassisted discovery, etc.). Random effects analyses of 580 comparisons revealed that outcomes were favorable for explicit instruction when compared to unassisted discovery under most conditions, d = -.38 (95% CI = -.44/-.31). In contrast, analyses of 360 comparisons revealed that outcomes were favorable for enhanced discovery when compared to other forms of instruction, d = .30 (95% CI = .23/.36). The findings suggest that unassisted discovery does not benefit learners, whereas feedback, worked examples, scaffolding, and elicited explanations do.
The Temporal Relationship between Daytime Napping and Memory Consolidation
Year of Dissertation:
2011
An extensive body of literature exists substantiating the idea that sleep facilitates the strengthening, stabilization, and protection of newly formed memories, aiding in consolidation from short-term to long-term stores. However, research as to the temporal boundaries of the benefit of sleep to declarative memory is deficient. It has been established that sleep benefits memory compared to equal time spent awake, but when sleep needs to occur relative to the learning period, as well as how much and what type of sleep is necessary, has been little explored. Additionally, researchers have focused on how the brain works on previously encoded information during sleep, but very few have addressed whether sleep prepares the brain to take on new information when it occurs prior to learning. Using efficient daytime naps, the present series of studies addressed these shortcomings and the results provided support exclusively to an active role for sleep in memory processing. Study I unexpectedly demonstrated superior performance for recognition memory with increased delay before sleep onset, resulting in increased slow wave sleep (SWS) in the later nap groups. Study II determined that sleep must progress into SWS, rather than merely Stages 1 and 2, for better short-term retention, subsequent protection from stimulus-related interference, and long-term consolidation, although even a brief nap provides temporary retention benefits over remaining awake. Examining sleep prior to learning in Study III, it was found that a 60-minute nap prepared the brain to more efficiently consolidate information, despite the fact that nap and wake groups encoded material equally. Overall, the present research provides clarification, although perhaps task-dependent, to the existing questions regarding the temporal relationship between sleep and learning. Additionally, the results proffer support for active processing during sleep potentially through standard consolidation and/or homeostatic downscaling of synaptic potentials, the major mechanistic theories ascribing a role for SWS in declarative memory processing.
IN THESE BONES THE ECONOMY OF THE WORLD: A MULTI-LOGICAL, MULTI-REPRESENTATIONAL CULTURAL STUDY
Year of Dissertation:
2011
In this work I offer critical interpretations of street skaters, images in schools, collaborative writing and discourses on Muslims in schools. Employing a phenomenological, hermeneutic approach, I have thought back on my experiences, made claims and supported them hermeneutically. As I have (in the tradition of critical pedagogy) told stories of being in the world, a critical perspective has anchored these stories to broader social, political and economic frameworks. Axiological concerns are at the forefront of this work, and the "so what?" question implicitly weaves through it. I do not seek to provide the answers, but rather to illuminate, through example, that asking questions of that which is taken for granted and connecting these questions to issues of power is a valid undertaking. In a world of truncated educational "accountability" this work joins those that seek to offer a counterpoints.
Power Supply Considerations for Capacitive Deionization Water Purification Systems
Year of Dissertation:
2009
Advisor:
Professor Norman Scheinberg
This research is about the power supply considerations and energy recovery schemes in water purification systems utilizing the Capacitive De-Ionization (CDI) method. The first chapter is a general introduction about the ever rising need for water in the world. It also talks about the drive behind this research. The most common methods for water desalination are discussed in Chapter II. Then, the method of CDI is discussed in detail in Chapter III. The model, applications and design considerations for CDI are discussed. Energy recovery in desalination methods is talked about in Chapter IV, with emphasis on energy recovery in CDI. Then a novel method for energy recovery in CDI is presented, showing superior results to prior art. Simulation and experimental results confirmed the validity of the method, and are presented. Power supply considerations for the CDI method are presented in Chapter V. Then, a novel power supply scheme is suggested.
THE EFFECTS OF ENRICHMENT ON COGNITION IN RATS (RATTUS NORVEGICUS)
Year of Dissertation:
2009
Abstract
The Vocal Behaviors of Captive North American River Otters (Lontra canadensis) Individual differences and shared repertoires
Year of Dissertation:
2011
The current information on the vocal repertoire of the North American River Otter is very limited. To date there have been no direct studies conducted on their repertories. In this study, I examined the vocal behavior of 12 captive river otters. The discriminant function analysis suggests that river otters have 4 distinct call types with 7 sub-call types and one call the whistle is unique to one group of pups. The results of the Kruskal-Wallis comparing acoustical structures shows strong evidence for the presence of individuality with some individuals showing greater differences in comparison to the others. I also examined the differences in sexes and age groups, and the results show that unique calls are present, and there are significant differences across groups when comparing acoustical structures. Finally, I examined the uses of vocalizations, and the results show a positive correlation between the duration, max frequency, and max power of the call and the arousal state of the individual producing the call. Specific call types also showed tendencies to be produced when the individual was in a particular interaction (asocial or social) and when in a particular arousal state.
ROUTING PROTOCOLS ENHANCEMENT FOR DELAY TOLERANT NETWORKS
Year of Dissertation:
2010
Routing in Delay/Disruption Tolerant Networks (DTN) is active area of research and acquires the attention of researchers as being the most adequate solution for the problem of intermittently connection in Mobile Ad hoc Networks (MANET). The challenge is to find a routing algorithm that can deal with dynamic environment causing networks to split and merge, considering nodes mobility.