1,727,845 research outputs found
2020 Commencement – School of Graduate Studies
No full textCeremony for students from the School of Graduate Studies
2021 Commencement – School of Graduate Studies
No full textCeremony for students from the School of Graduate Studies
Archived Website - Horace H. Rackham School of Graduate Studies, 2003
No full textTo access this archived Website, download the .ZIP file and extract the contents with the utility of your choice. Using a Web browser, open the 'BHL-start-here.html' file found within to review additional information from the Bentley Historical Library and follow a link to view the archived homepage.Archived version of the Horace H. Rackham School of Graduate Studies website as of May 22, 2003. Documents the academic programs, accomplishments, resources, events, and people at the Rackham Graduate School. Content includes important news and announcements, publications (such as newsletters and course catalogs), and information about admissions, curriculum, degree requirements, faculty, and the overall mission of the Rackham School of Graduate Studies. Specific publications include the 2002 Graduate Student Handbook, 2002-2003 issues of the Rackham E-Mail Newsletter, 2002-2003 Rackham Alumni Magazine, and The Rackham Dissertation Handbook. Website preserved using the Teleport Pro application.http://deepblue.lib.umich.edu/bitstream/2027.42/102025/1/2003RACKHAM.zi
Factoring and learning algorithms for low-depth algebraic circuits
No full textPolynomial factoring and learning arithmetic circuits (a.k.a. circuit-reconstruction) are two fundamental problems in algebraic complexity. They are deeply connected to the questions of circuit lower bounds and polynomial identity testing (PIT). In this dissertation, we present various new results on learning and factoring of low-depth circuits, while emphasizing these connections.Ph.D.Includes bibliographical reference
Performance evaluation of redundancy techniques for distributed storage and computing systems
No full textToday’s challenging problems in science and industry are solved by complex data-driven algorithms. Distributed computing paradigm has emerged as the way to satisfy the growing computational and storage demands of these algorithms. Systems that enable distributed computing are desired to execute workloads with fast and predictable performance. However these systems have long been plagued by the runtime performance variability, which in turn significantly slows down workload execution and reduce performance predictability.Includes bibliographical referencesPh.D
Role of short-term dynamics of synpses between dentate gyrus interneurons in shaping excitability in normal and epileptic circuits
No full textTemporal lobe epilepsy (TLE) is a relatively common form of epilepsy that is difficult to manage and is characterized by recurrent unprovoked seizures originating in the temporal lobe of the brain. Seizures in TLE often start in the hippocampus, and are associated with structural and functional changes in the dentate gyrus (DG), a region within the hippocampus. Seizure activity can lead to physiologic changes that can underlie or worsen the severity of epilepsy. In order to elucidate the mechanisms underlying TLE, it is important to develop a detailed understanding of the specific physiological changes and their effects on network activity patterns.
The main projection neuron in the DG is the granule cell (GC), an excitatory neuron. However, most of the other cell types in the DG are inhibitory interneurons. Two of these inhibitory interneurons are parvalbumin-expressing, fast-spiking basket cells (fsBCs), and accommodating cells (ACs). Recent research has shown that the synapses between ACs and fsBCs show a functional reduction in reliability of synaptic transmission after experimental seizure induction. Previous studies identified that this change affects oscillatory coupling in simulated networks including fsBCS and ACs. Similar network oscillation disruptions in the DG have been linked to complications of epilepsy. In addition to baseline characteristics of synaptic release, synapses show activity-dependent changes in synaptic properties. Of particular relevance, synapses from fsBCs undergo short-term depression and synapses from ACs undergo short-term facilitation. However, the impact of such short-term synaptic dynamics on large-scale circuit activity patterns is not commonly modeled.
This study used computational modeling to examine how the short term dynamics of synapses between ACs and fsBCs modify network excitability and oscillations in networks with normal and epileptic synaptic characteristics. A model of the facilitation-depression synapse was successfully implemented in the NEURON programming environment and applied to a network of DG excitatory and inhibitory neurons. Cell-type specific short term synaptic dynamics were constrained based on published experimental data in specific cell types. Excitability was compared between models of a control network of DG neurons and a post-seizure network of DG neurons. The post-seizure network was modeled to mimic the functional reduction in reliability between ACs and fsBCs seen in experimental seizure induction by decreasing the probability of synaptic release in response to firing. Implementation of the seizure-induced decrease in AC to fsBC synaptic release probability failed to alter average granule cell firing frequency and duration in response to synchronous afferent activation. Excitability was also compared between networks incorporating synapse specific short term synaptic dynamics and networks that did not. Inclusion of short term synaptic dynamics led to modest increases in excitability which were not statistically significant. In contrast to the limited change in excitability, comparison of oscillatory behavior between control and post-seizure networks revealed an increase in coherence and a change in frequency power spectra. Addition of short term synaptic dynamics resulted in decreased coherence and a change in frequency power spectra. Overall, it was shown that a decrease in functional reliability in AC to fsBC synapses, when modeled with biologically realistic facilitation-depression synapses, has little effect on network excitability, but significant effects on network oscillatory behavior.M.S.Includes bibliographical references
Saintly borrowings: the hagiographic impulse in late Medieval texts
No full textThis dissertation looks at the generic tropes of hagiography and how late medieval writers in other genres borrowed them, namely explicit moral clarity, the ability to appeal to alternate forms of authority, and the capacity to rewrite genealogy. It then examines how and why these modes of thinking were used through a series of case studies. For instance, in the anonymous Sir Gowther, the author relies on the possibility of rewriting genealogy in a partially successful attempt to relieve anxiety about the role of violence in a chivalric society and the dangers of illegitimacy in a patrilineal culture. Kempe draws on the language of hagiography in order to establish herself in the communities of saints and to interpret the resistance and scorn she encounters as a form of martyrdom. Finally, The Legend of Good Women juxtaposes classical tradition with hagiographic structure, placing the two traditions in opposition to each other in order to create a liminal space wherein feminine voices may have room to speak.Ph.D.Includes bibliographical reference
Assessing the quality of user-generated content in the presence of automated quality scores
No full textWith the proliferation in participatory web culture, individuals not only create but also consume content present in crowdsourced environments such as blogs, question-answering systems. Studies have revealed users often employ the content present in them to make a range of choices, from issues in everyday life to important life decisions, without paying much attention to the quality. In the recent years, studies have demonstrated K-12 students’ over reliance on these crowdsourced sites to fulfil their academic course requirements. Therefore, it is important to evaluate users’ cognizance while evaluating the quality of content in these venues. But before identifying to what extent do users make use of quality while evaluating user-generated content, it is important to learn what constitutes of quality. To address these issues, this dissertation expounds to the problems in a three-step process. First, the dissertation begins by developing a conceptual framework for evaluating quality of user-generated content consisting of constructs such as correct, credible, clear, and complete. The second step involves validating the framework with the help of twelve experts i.e. librarians to attest the developed framework and using this validation to come to generate automated methodologies to evaluate the quality of content to provide quality scores. To further investigate, the third step delves deeper into users’ reliance on the automated quality scores by conducting a user study. 45 undergraduate students were recruited to investigate their use of automated quality scores while completing their tasks under three conditions – users provided with genuine quality scores, users provided with manipulated quality scores, and users provided with no quality scores (control). As prior research has indicated users task completion is dependent on the task-type provided, this user study involves providing users with different task types such as ranking and synthesis in the presence of quality scores. To further comprehend users’ use of quality scores while completing the tasks, the author makes use of eye-tracking metrics such as total number of gazes, gaze duration, and the number of gazes on the quality scores to evaluate their use by the users. Analyses was performed with the help of fixation data, users’ responses to pre and post task questionnaires, along with task scenarios along with interview transcripts. ANOVA and other statistical analyses were conducted and no statistical differences were found between users’ use of quality scores and the type of task. It was also found that users primarily considered the constructs - correct and credible from the charts from the qualitative data. Additionally, it was also found that users made use of the quality scores primarily when they had little familiarity with the topic. The study provided insights into how and to what extent do users considered the role of quality while completing the task provided. The contribution of this human information behavior study is of twofold: users’ reliance on an automated score provided by an intelligent tool along with studying users’ confidence in considering quality in evaluating user-generated content.Ph.D.Includes bibliographical reference
Inhibition of histone deacetylase 3 via RGFP966 facilitates exceptionally specific and enduring memory for excitatory and inhibitory sound-signal associations
No full textEpigenetic mechanisms that modulate gene expression are key to regulating long-term memory (LTM) formation, and are known to exert control on memory formation in multiple systems of the adult brain, including the sensory cortex. Chromatin modifications have been shown to have powerful effects on experience-dependent transcription for neuroplasticity underlying memory processes. One mechanism for chromatin modification is histone acetylation. Histone acetyltransferases (HATs) generally facilitate LTM formation by promoting gene expression, while histone deacetylases (HDACs) tend to have gene silencing effects, and negatively regulate LTM. Thus, blocking the action of HDACs has been shown to facilitate LTM formation. Because sensory cortex undergoes learning-induced remodeling over a lifetime, here we aimed to identify the ways in which HDAC-inhibition acts to facilitate LTM using a standard model of auditory memory and cortical plasticity. Auditory cortical plasticity in particular has been extensively studied in learning and memory processes. Representational plasticity in primary auditory cortex (A1) is known to reflect the formation of strong and sound-selective associative memory for behaviorally relevant sound features. In this present study, we used RGFP966, a class I HDAC inhibitor with selectivity for HDAC3 that has been shown to modulate associative learning-induced A1 plasticity (Bieszczad et al., 2015), to facilitate memory consolidation in rats learning a 2-tone sound frequency discrimination (2TD) task. We found that systemic treatments of the HDAC3-inhibitor early in 2TD task training facilitated associative learning for both excitatory (CS+) and inhibitory (CS-) sound signals, and altered the LTM formed in two ways that were independent of the final performance level achieved, which was equivalent between groups. We found that HDAC3-inhibition enhanced memory specificity for the sound-frequency of the two pure-tone CS cues, and strengthened memory for the excitatory and inhibitory sound-specific associations. Moreover, the behavioral effects of an initial, limited bout of HDAC3-inhibitor were long-lasting, enduring for at least weeks following the last administration of RGFP966. The present results support a role for HDAC3 during auditory memory consolidation by regulating the specificity and strength of newly learned sound-signal associations. This conclusion complements existing research on the effects of HDAC-inhibitors by providing a potential behavioral explanation for long-term memory enhancements.M.S.Includes bibliographical referencesby Andrea Shan
An investigation of the drying process in pickering foams
No full textPickering foams, aqueous foams stabilized by solid particles, can be used as a precursor to fabricate solid porous polymers, ceramics, and composite materials. The fabrication process usually comprises of two subsequent steps of drying and solidification (e.g. sintering) after foam is prepared. Drying (or aging) in aqueous Pickering foams is a complex transport process which involves evaporation and drainage (induced by gravity) of the excess liquid along with deformation of the foam and possible formation of cracks caused by capillary-induced stresses. Crack formation is therefore depended on the drying conditions and the mechanical properties of sample. A comprehensive understanding of the drying process can provide us with predictive tools to select efficient process parameters (e.g. required drying time prior to sintering) as well as providing input prameters for developing numerical models. In this thesis, we first provide experimental data (end of drying time, average moisture content, and effective moisture diffusivity) on drying of Pickering foams stabilized by polymer particles under controlled conditions (i.e. relative humidity and temperature). Drying curves are presented for samples of various initial thicknesses and shapes on substrates of different hydrophobicity and temperatures. Moisture transport is represented via calculating the effective moisture diffusivity coefficients using method of slope. Also, we investigate drying for a bi-component Pickering foam prepared using Multi-walled Carbon Nanotubes (MWCNTs) and polymer particles. We show that the effective moisture diffusivity increases as the average moisture content decreases for all trials and that all data can be collapsed on a master curve. Also, effective moisture diffusivity increased as initial sample thickness as well as substrate temperature increase. On the other hand, effective moisture diffusivity does not depend strongly on the sample shape and MWCNTs concentration. In next part, we explore the effect of initial sample thickness and shape, substrate temperature and wettability, as well as MWCNTs concentration on the crack formations in the samples. We demonstrate that substrate wettability, initial sample thickness, and MWCNTs concentration have a strong influence on the formation and propagation of cracks. We found that decreasing the wettability of the substrate reduces crack formation. Also, increasing the initial sample thickness reduces crack formation. On the contrary, increasing the MWCNTs concentration increases crack formation for all types of substrates. We demonstrate that substrate temperature and sample shape do not seem to influence crack formation but these parameters influence the crack patterns. Such information can be beneficial in using these foams as a precursor to fabricate porous composite porous materials.Ph.D.Includes bibliographical referencesby Omer S. Alabidalkree
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