VictorJuiz/thesis huggingface dataset:
Power MOSFETs with Enhanced Electrical Characteristics

The integration of high voltage power transistors with control circuitry to form smart Power Integrated Circuits (PIC) has numerous applications in the areas of industrial and consumer electronics. These smart PICs must rely on the availability of high performance power transistors. In this thesis, a vertical U-shaped gate MOSFET (UMOS) and a lateral Extended Drain MOSFET (EDMOS) with enhanced electrical characteristics are proposed, developed and verified via experimental fabrication. The proposed new process and structure offers superior performance, such as low on-resistance, low gate charge and optimized high breakdown voltage. In the vertical power UMOS, a novel trenched Local Oxidation of Silicon (LOCOS) process has been applied to the vertical gate structure to reduce the gate-to-source overlap capacitance (Cgs). A 40% reduction in Cgs is achieved when compared to conventional UMOS. A specific on-resistance Ron, sp = 60m2·mm2 is observed, which is 45% better than that of the conventional UMOS. The improvement in the device’s Figure-of-Merit (FOM = Ron × Qg) is about 58%. A floating RESURF EDMOS (BV=55V, Ron,sp=36.5m2·mm2) with a 400% improvement in the Safe Operating Area (SOA) when compared to the conventional EDMOS structure is also presented. The proposed EDMOS employs both drain and iii source engineering to enhance SOA, not only via reducing the base resistance of the parasitic bipolar transistor, but also suppressing the base current of the parasitic bipolar transistor under high Vgs and high Vds conditions. A buried deep Nwell allows the device to have better trade-off between breakdown voltage and on-resistance. Finally, in order to achieve low gate charge in the EDMOS, a novel orthogonal gate electrode is proposed to reduce the gate-to-drain overlap capacitance (Cgd). The orthogonal gate has both horizontal and vertical sections for gate control. This device is implemented in a 0.18?m 30V HV-CMOS process. Compared to a conventional EDMOS with the same voltage and size, a 75% Cgd reduction is observed. The FOM is improved by 53%.

Keywords: Power MOSFETs
Advisor: Ng, Wai Tung
Mediated Reality and Location Awareness to Facilitate Topographical Orientation

Topographical orientation is the ability to orient oneself within the environment and to navigate through it to specific destinations. Topographical disorientation (TD) refers to deficits in orientation and navigation in the real environment, and is a common sequela of brain injuries. People with TD often have difficulties interacting with and perceiving the surrounding environment. The literature suggests that patients with TD are likely to benefit from research leading to clinical standards of practice and technology to facilitate topographical orientation. In the light of the above, the objectives of this thesis were to investigate methods of realizing a context-aware, wearable mediated environment system for indoor navigation, and to develop a standard method of quantifying the impact of such a system on indoor navigation task performance. In realizing these objectives, we first conducted an extensive literature review of in-door localization systems. This review served to identify potential technologies for an indoor, in-situ wayfinding assistive device. Subsequently, an automated navigation algorithm was designed. Our algorithm reduced the navigational effort of simulated patients with topographical disorientation while accounting for the physical abilities of the patient, environmental barriers and dynamic building changes. We introduced and demonstrated a novel energy-based wayfinding metric, which is independent of route complexity. An experiment was conducted to identify preferred graphical navigation tools for mediated reality wayfinding guidance. Different combinations of spatial knowledge, graphical presentations and reference frames were considered in the experiment. The data suggested that the locator and minimap are the preferred navigational tools. Two unique optical-inertial localization systems for real-time indoor human tracking were created. The first localization system was oriented to pedestrians, while the second was implemented on a wheelchair. Empirical tests produced localization accuracies comparable to those reported in literature. Finally, a fully operational mediated reality location aware system for indoor navigation was realized. Tests with human participants indicated a significant reduction in physical effort in comparison to the no-tool condition, during wayfinding tasks in an unfamiliar indoor environment. Collectively, the findings and developments of this thesis lay the foundation for future research on wearable, location-based navigational assistance for individuals with wayfinding difficulties.

Keywords: Localization
Navigation
Advisor: Chau, Tom
Mann, Steve
Modeling and Optimization of Delay and Power for Key Components of Modern High-performance Processors

In designing a new processor, computer architects consider a myriad of possible organizations and designs to decide which best meets the constraints on performance, power and cost for each particular processor. To identify practical designs, architects need to have insight into the physical-level characteristics (delay, power and area) of various components of modern processors implemented in recent fabrication technologies. During early stages of design exploration, however, developing physical-level implementations for various design options (often in the order of thousands) is impractical or undesirable due to time and/or cost constraints. In lieu of actual measurements, analytical and/or empirical models can offer reasonable estimates of these physical-level characteristics. However, existing models tend to be out-dated for three reasons: (i) They have been developed based on old circuits in old fabrication technologies; (ii) The high-level designs of the components have evolved and older designs may no longer be representative; and, (iii) The overall architecture of processors has changed significantly, and new components for which no models exist have been introduced or are being considered. This thesis studies three key components of modern high-performance processors: Counting Bloom Filters (CBFs), Checkpointed Register Alias Tables (RATs), and Compacted Matrix Schedulers (CMSs). CBFs optimize membership tests (e.g., whether a block is cached). RAT and CMS increase the opportunities for exploiting instruction-level parallelism; RAT is the core of the renaming stage, and CMS is an implementation for the instruction scheduler. Physical-level studies or models for these components have been limited or non-existent. In addition to investigating these components at the physical level, this thesis (i) proposes a novel speed- and energy-efficient CBF implementation; (ii) studies how the number of RAT checkpoints affects its latency and energy, and overall processor performance; and, (iii) studies the CMS and its accompanying logic at the physical level. This thesis also develops empirical and analytical latency and energy models that can be adapted for newer fabrication technologies. Additionally, this thesis proposes physical-level latency and energy optimizations for these components motivated by design inefficiencies exposed during the physical-level study phase.

Keywords: Processor design
Computer architecture
Physical-level implementation
Advisor: Moshovos, Andreas
Disinhibition at Feedforward Inhibitory Synapses in Hippocampal Area CA1 Induces a Form of Long-term Potentiation

One of the central questions of neuroscience research has been how the cellular and molecular components of the brain give rise to complex behaviours. Three major breakthroughs from the past sixty years have made the study of learning and memory central to our understanding of how the brain works. First, the psychologist Donald Hebb proposed that information storage in the brain could occur through the strengthening of the connections between neurons if the strengthening were restricted to neurons that were co-active (Hebb, 1949). Second, Milner and Scoville (1957) showed that the hippocampus is required for the acquisition of new long-term memories for consciously accessible, or declarative, information. Third, Bliss and Lømo (1973) demonstrated that the synapses between neurons in the dentate gyrus of the hippocampus could indeed be potentiated in an activity-dependent manner. Long-term potentiation (LTP) of the glutamatergic synapses in area CA1, the primary output of the hippocampus, has since become the leading model of synaptic plasticity due to its dependence on NMDA receptors (NMDARs), required for spatial and temporal learning in intact animals, and its robust pathway specificity. Using whole-cell recording in hippocampal slices from adult rats, I find that the efficacy of synaptic transmission from CA3 to CA1 can in fact be enhanced without the induction of classic LTP at the glutamatergic inputs. Taking care not to directly stimulate inhibitory fibers, I show that the induction of GABAergic plasticity at feedforward inhibitory inputs in CA1 results in the reduced shunting of excitatory currents, producing a long-term increase in the amplitude of Schaffer collateral-mediated postsynaptic potentials which is dependent on NMDAR activation and is pathway specific. The sharing of these fundamental properties with classic LTP suggests the possibility of a previously unrecognized target for therapeutic intervention in disorders linked to memory deficits, as well as a potentially overlooked site of LTP expression in other areas of the brain.

Keywords: Synaptic plasticity
Hippocampus
Advisor: Woodin, Melanie A.
Molecular Mechanism of Podosome Formation and Proteolytic Function in Human Bronchial Epithelial Cells

In the lung, epithelial cell migration plays a key role in both physiological and pathophysiological conditions. When the respiratory epithelium is injured, the epithelial lining in the respiratory system can be seriously damaged. Spreading and migrating of the surviving cells neighboring a wound are essential for airway epithelial repair. When the repair process is affected, aberrant remodeling may occur, which is important in the pathogenesis of lung diseases. However, in comparison with other cellular and molecular functions in the respiratory system, our understanding on lung epithelial cell migration and invasion is limited. To gain insight into the molecular mechanisms that govern these cellular processes, I asked whether normal (non-cancerous) human airway epithelial cells can form podosomes, a cellular structure discovered from cancer and mesenchymal cells that controls cell migration and invasion. I found that phorbol-12, 13-dibutyrate (PDBu), a protein kinase C (PKC) activator, induced podosome formation in primary normal human bronchial epithelial cells, and in normal human airway epithelial BEAS2B cells. PDBu-induced podosomes were capable of degrading fibronectin-gelatin-sucrose matrix. PDBu also increased the invasiveness of these epithelial cells. I further demonstrated that PDBu-induced podosome formation was mainly mediated through redistribution of conventional PKCs, especially PKCα, from the cytosol to the podosomes, whereas atypical PKCζ played a dominant role in the proteolytic activity of podosomes through recruitment of MMP-9 to podosomes, and MMP-9 secretion and activiation. I also found that that PDBu can activate PI3K/Akt/Src and ERK1/2 and JNK but not p38. PI3K, Akt and Src were critical for podosome formation, whereas ERK1/2 and JNK mediated the proteolytic activity of podosomes via MMP-9 recruitment, gene expression, release and activation without affecting podosome assembly. Podosomes are important for epithelial cell migration and invasion, thus contributing to respiratory epithelial repair and regeneration. My thesis work unveils the molecular mechanisms that regulate podosomal formation and proteolytic function in normal human bronchial epithelial cells. These novel findings may enhance our understanding of cell migration and invasion in lung development and repair. Similar mechanisms may be also applicable to other cell types in distinct organs.

Keywords: cell biology
cell migration
cell invasion
protein kinase C
podosome
matrix degradation
invadopodia
lamellipodia
membrane ruffle
Advisor: Liu, Mingyao
The Activation of Novel Calcium-dependent Pathways Downstream of N-methyl-D-aspartate Receptors

Calcium (Ca2+) influx through N-methyl-D-asparate receptors (NMDARs) is widely held to be the requisite step initiating delayed neuronal death following ischemic stroke. However, blocking NMDARs fails to prevent the accumulation of intracellular Ca2+ ([Ca2+]i) and subsequent neurotoxicity. This suggests that alternate, as yet uncharacterized Ca2+-influx pathways exist in neurons. Transient receptor melastatin 2 (TRPM2) is a Ca2+-permeable member of the transient receptor potential melastatin family of cation channels whose activation by reactive oxygen/nitrogen species (ROS/RNS) and ADP-ribose (ADPR) is linked to cell death. While these channels are broadly expressed in the central nervous system (CNS), the presence of TRPM2 in neurons remains controversial and more specifically, whether they are expressed in neurons of the hippocampus is an open question. Here, I employ a combination of molecular, biochemical and electrophysiological approaches to demonstrate that functional TRPM2 channels are expressed in pyramidal neurons of the hippocampus. Unlike in heterologous expression systems, the ADPR-dependent activation of TRPM2 in neurons required a concomitant rise in [Ca2+]i via either voltage-dependent Ca2+ channels or NMDARs. While short, repeated NMDA applications activated a TRPM2-like current in the absence of exogenous ADPR, sustained NMDA application to hippocampal neurons resulted in the activation of a pannexin1 (Px1) hemichannel. Px1 hemichannels are large conductance, nonjunctional gap junction channels that can be activated following periods of oxygen-glucose deprivation (OGD) in neurons. Activation of Px1 required the influx of Ca2+ through NMDARs. Supplementing the intracellular milieu with adenosine triphosphate (ATP) prevented Px1 activation, suggesting that hemichannels may be activated during periods of mitochondrial dysfunction and metabolic failure. Our findings have potential implications for the treatment of diseases such as cerebral ischemia and Alzheimer’s disease (AD) as they implicate two novel ion channels in the excitotoxic signaling cascade activated downstream of NMDARs.

Keywords: ion channels
TRPM2
pannexin
calcium
NMDA receptors
Advisor: MacDonald, John F.
Red October: Left-Indigenous Struggles in Bolivia, 2000-2005

This dissertation provides an analytical framework for understanding the left-indigenous cycle of extra-parliamentary insurrection in Bolivia between 2000 and 2005. It draws from Marxist and indigenous-liberationist theory to challenge the central presuppositions of liberal-institutionalist understandings of contemporary indigenous politics in Latin America, as well as the core tenets of mainstream social movement studies. The central argument is that a specific combination of elaborate infrastructures of class struggle and social-movement unionism, historical traditions of indigenous and working-class radicalism, combined oppositional consciousness, and fierce but insufficient state repression, explain the depth, breadth, and radical character of recent left-indigenous mobilizations in Bolivia. The coalition of insurrectionary social forces in the Gas Wars of 2003 and 2005 was led by indigenous informal workers, acting in concert with formal workers, peasants, and to a smaller degree, middle-class actors. The indigenous informal working classes of the city of El Alto, in particular, utilized an elaborate infrastructure of class struggle in order to overcome structural barriers to collective action and to take up their leading role. The supportive part played by the formal working class was made possible by the political orientation toward social-movement unionism adopted by leading trade-union federations. Radicalized peasants mobilized within the broader alliance through their own rural infrastructure of class struggle. The whole array of worker and peasant social forces drew on longstanding popular cultures of indigenous liberation and revolutionary Marxism which they adapted to the novel context of the twenty-first century. These popular cultures ultimately congealed in a new combined oppositional consciousness, rooted simultaneously in the politics of indigenous resistance and class struggle. This collective consciousness, in turn, strengthened the mobilizing capacities of the popular classes and reinforced the radical character of protest. At key junctures, social movement leaders were able to synthesize oppositional consciousness into a focused collective action frame of nationalizing the natural gas industry. Finally, throughout the left-indigenous cycle, ruthless state repression was nonetheless insufficiently powerful to wipe out opposition altogether and therefore acted only to intensify the scale of protests and radicalize demands still further. The legitimacy of the neoliberal social order and the coercive power required to reproduce it were increasingly called into question as violence against civilians increased.

Keywords: Bolivia
indigenous
left
working class
social movements
neoliberalism
class struggle
Latin America
multiculturalism
Marxism
Advisor: Teichman, Judith A.
Nature and the Moral Evolution of Humanity in Nietzsche's "On the Genealogy of Morals"

The dissertation begins by discussing recent critical treatments of Nietzsche in the work of Alasdair MacIntyre and Jürgen Habermas, then gives a brief discussion of the broader scholarly reception of Nietzsche’s political thought. The body of the dissertation proceeds through the text of the Second Essay of Nietzsche’s On the Genealogy of Morals, trying to explicate his account of the origin of political society. The dissertation attempts in the first place to show that the historical narrative Nietzsche offers in the Second Essay is coherent, then to illuminate the details of his account of the rise of political society, and thus of civilized morality (what Nietzsche calls “the bad conscience”), and finally to detail the different stages in the development of the bad conscience. The dissertation lays particular emphasis on determining the relation between what Nietzsche calls ressentiment and the bad conscience. The dissertation also attempts to shed light on Nietzsche’s view of the relation between nature and political society and morality, as he expresses it both in his analysis of the bad conscience and in the somewhat more thematic discussion of this question at the beginning of the Essay.

Keywords: Nietzsche
morality
political philosophy
Advisor: Orwin, Clifford
Improving Breastfeeding Outcomes: A Pilot Randomized Controlled Trial of a Self-efficacy Intervention with Primiparous Mothers

Breastfeeding is recommended as the optimal source of nutrition for newborns for the first 6 months of life and beyond with the addition of complementary foods. While breastfeeding initiation rates have been increasing, duration rates remain a concern as many women prematurely discontinue due to difficulties encountered rather than maternal choice. In addition, there is a sizable gap between rates of exclusive breastfeeding and current recommendations. Targeting modifiable variables that may be amenable to intervention is one strategy to improve breastfeeding outcomes. One such modifiable variable is breastfeeding self-efficacy. Although research has clearly shown that breastfeeding self-efficacy is predictive of breastfeeding duration and exclusivity, it is unknown whether it can be enhanced to improve breastfeeding outcomes. The purpose of this pilot randomized controlled trial was to examine the feasibility and compliance of a newly developed trial protocol and the acceptability of an intervention to increase breastfeeding self-efficacy in the immediate postpartum period. Secondary outcomes included determining whether there were any trends between groups related to breastfeeding self-efficacy, duration, and exclusivity. Participants included 150 primiparous mothers who were breastfeeding their healthy, full-term infants. Eligible and consenting mothers were randomized to either a control group (standard postpartum care) or an intervention group (standard postpartum care plus the self-efficacy intervention). Participants allocated to the intervention group received three individualized, self-efficacy enhancing sessions with the researcher; two sessions were conducted in hospital, and one was administered via telephone 1 week following hospital discharge. A research assistant blinded to group allocation collected outcome data at 4 and 8 weeks postpartum. The results suggested that the administration of the intervention was feasible and that there was a high degree of protocol compliance; the majority of participants reported that the intervention was beneficial. Secondary outcomes identified that there was a trend among participants in the intervention group to have improved breastfeeding outcomes, including higher rates of breastfeeding self-efficacy, duration, and exclusivity at 4 and 8 weeks postpartum. Preliminary evidence also suggested that the self-efficacy intervention may have assisted to decrease perceptions of insufficient milk supply among the intervention group participants. Overall, the findings from this pilot trial indicated that a larger trial is warranted.

Keywords: breastfeeding
self-efficacy
randomized controlled trial
intervention
pilot study
Advisor: Dennis, Cindy-Lee E.
Stremler, Robyn
Norman, Cameron
Quantification of Chemical Erosion in the Divertor of the DIII-D Tokamak

The International Thermonuclear Experimental Reactor (ITER) is currently designed to use graphite targets in the divertor for power handling and impurity control. Understanding and quantifying chemical sputtering is therefore key to the success of fusion as a clean energy source. The principal goal of this thesis is to design and carry out experiments, then analyze and interpret the results in order to elucidate the role of chemical sputtering in carbon sources in the DIII-D tokamak. A self-contained gas puff system has been designed, constructed, and employed for in-situ study of chemical erosion. The porous plug injector (PPI) releases methane through a porous graphite surface into the divertor plasma at a precisely calibrated rate, minimizing perturbation to local plasma while replicating the immediate environment of methane molecules released from a solid graphite surface more accurately than done previously. For the first time in a tokamak environment, the methane flow rate used in a puffing experiment was the same order of magnitude as that expected from laboratory experiments for intrinsic chemical sputtering. Effective photon efficiencies for injection are reported; results are found to have significant dependencies on surface conditions and the divertor operating regime. The contribution of sputtering processes to sources of C0 and C+ are assessed through measurement of background and incremental spectroscopic emissions of both physically and chemically-released sputtering products and by CI, 910 nm line profile fitting. Comparison of background and incremental emissions of chemically-released products demonstrate a dramatic drop in production of CH in cold and detached conditions. Finally, the chemical erosion yield is calculated in both attached and cold-divertor conditions and found to be much closer to that measured ex-situ in ion beam experiments than previously determined in DII-D. These observations represent a positive result for ITER which will operate at all times with a detached divertor, i.e., a low chemical sputtering yield. Results and analysis techniques presented here point the direction for future experiments with the PPI for study of chemical sputtering in the tokamak edge environment.

Keywords: Plasma
Fusion
Spectroscopy
Hydrocarbon
Advisor: Stangeby, Peter C.