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Delta-Sigma Modulators with Low Oversampling RatiosCaldwell, Trevor 23 February 2011 (has links)
This dissertation explores methods of reducing the oversampling ratio (OSR) of both delta-sigma modulators and incremental data converters. The first reduced-OSR architecture is the high-order cascaded delta-sigma modulator. These delta-sigma modulators are shown to reduce the in-band noise sufficiently at OSRs as low as 3 while providing power savings. The second low OSR architecture is the high-order cascaded incremental data converter which possesses signal-to-quantization noise ratio (SQNR) advantages over equivalent delta-sigma modulators at low OSRs. The final architecture is the time-interleaved incremental data converter where two designs are identified as potential methods of increasing the throughput of low OSR incremental data converters. A prototype chip is designed in 0.18um CMOS technology which can operate in three modes by simply changing the resetting clock phases. It can operate as an 8-stage pipeline analog-to-digital (A/D) converter, an 8th-order cascaded delta-sigma modulator, and an 8th-order cascaded incremental data converter with an OSR of 3.
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Ground Reaction Forces in Feet with Morton's SyndromeGraydon, Maclean 14 January 2013 (has links)
Morton’s syndrome is a foot condition where the 1st metatarsal does not protrude as far distally as the 2nd metatarsal. Clinicians believe that short 1st metatarsal protrusion affects foot mechanics and leads to painful conditions of the foot. Normal protrusion ratio of the 1st and 2nd metatarsal has not been delineated in scientific literature, and little is known about the mechanics of feet with short 1st metatarsal protrusion beyond anecdotal clinical evidence. In the first part of this two-part study, a novel tool was developed to guide metatarsal measurement and reduce measurement error so values for normal metatarsal protrusion ratios could be established. In the second part, subjects were divided into those with shorter and longer than average 1st metatarsal protrusion ratio and we measured if there were any differences in the foot-floor forces between the two groups.
In Part 1, the feet of 65 healthy subjects were measured with a novel measurement tool and it was determined that the average ratio (1st metatarsal/2nd metatarsal) was 0.902, suggesting a 1st metatarsal that does not protrude as far distally as the 2nd metatarsal. For Part 2, participants were divided into two groups: the short 1st metatarsal group had a ratio of more than one standard deviation below the mean (0.866 or lower) while the control group had a metatarsal ratio of more than one standard deviation above the mean (0.938 or higher).
We hypothesized that short 1st metatarsal protrusion would cause an imbalance across the forefoot because the 1st metatarsal would not be able to carry the required load on the medial side of the foot; however, the results of the gait study did not show this as only forces in the walking direction near toe-off correlated with metatarsal protrusion ratio. We can only speculate as to the relationship between the metatarsal protrusion ratio and increased shear force in the walking direction, but it is possible that to compensate for the diminished stabilizing capacity of the shorter 1st metatarsal, the foot must push off with more force to propel the body forward. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2013-01-14 14:38:55.255
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Variations on the Theme of CachingGaspar, Cristian January 2005 (has links)
This thesis is concerned with caching algorithms. We investigate three variations of the caching problem: web caching in the Torng framework, relative competitiveness and caching with request reordering. <br /><br /> In the first variation we define different cost models involving page sizes and page costs. We also present the Torng cost framework introduced by Torng in [29]. Next we analyze the competitive ratio of online deterministic marking algorithms in the BIT cost model combined with the Torng framework. We show that given some specific restrictions on the set of possible request sequences, any marking algorithm is 2-competitive. <br /><br /> The second variation consists in using the relative competitiveness ratio on an access graph as a complexity measure. We use the concept of access graphs introduced by Borodin [11] to define our own concept of relative competitive ratio. We demonstrate results regarding the relative competitiveness of two cache eviction policies in both the basic and the Torng framework combined with the CLASSICAL cost model. <br /><br /> The third variation is caching with request reordering. Two reordering models are defined. We prove some important results about the value of a move and number of orderings, then demonstrate results about the approximation factor and competitive ratio of offline and online reordering schemes, respectively.
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A Comparison Of Pharmacist Managed Anticoagulation Therapy To Non-Pharmacist Managed Therapy: A Meta-analysisBishop, Benjamin January 2010 (has links)
Class of 2010 Abstract / OBJECTIVES: To compare the INR-based results of pharmacist anticoagulation management services to non-pharmacist managed anticoagulation therapy.
METHODS: A meta-analysis was performed using studies that reported on pharmacists’ services and interventions in anticoagulation. Two reviewers independently assessed each record retrieved by the literature search, and studies were eliminated if both reviewers agreed that the study did not meet the inclusion criteria. The analysis found eight studies that were eligible for inclusion. The primary independent variable was the presence or absence of pharmacist services. The primary dependent variables were the proportion of patients within INR range, the duration of time within that range, and the time required to achieve that range. Extracted data were pooled and entered into the meta-analysis, and a forest plot was constructed. The a-priori alpha level was 0.05.
RESULTS: The eight studies were divided into two groups: The INR group consisted of four studies which used INR test data points as the unit of analysis. The Patient group included four studies which measured the patient’s INR only at the end of the study. The INR group demonstrated a significant difference favoring pharmacist services, with a p-value of 0.02 for the group. There was no significant difference between pharmacist services and the control group with respect to the Patient group. When all eight studies were pooled together, the overall forest plot did demonstrate significant favorability for pharmacist services, with an odds ratio of 1.58, indicating that pharmacist provided services improved care by 58% (Z = 2.8;p p = 0.01).
CONCLUSIONS: The advantage of a pharmacist service in reaching goal INR was significant compared to the control group of non- pharmacist care.
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Characterizing octagonal and rectangular fibers for MAROON-XSutherland, Adam P., Stuermer, Julian, Miller, Katrina R., Seifahrt, Andreas, Bean, Jacob L. 22 July 2016 (has links)
We report on the scrambling performance and focal-ratio-degradation (FRD) of various octagonal and rectangular fibers considered for MAROON-X. Our measurements demonstrate the detrimental effect of thin claddings on the FRD of octagonal and rectangular fibers and that stress induced at the connectors can further increase the FRD. We find that fibers with a thick, round cladding show low FRD. We further demonstrate that the scrambling behavior of non-circular fibers is often complex and introduce a new metric to fully capture non-linear scrambling performance, leading to much lower scrambling gain values than are typically reported in the literature (<1000 compared to 10,000 or more). We find that scrambling gain measurements for small-core, non-circular fibers are often speckle dominated if the fiber is not agitated.
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Methods to measure mass transfer kinetics, partition ratios and atmospheric fluxes of organic chemicals in forest systemsBolinius, Damien Johann January 2016 (has links)
Vegetation plays an important role in the partitioning, transport and fate of hydrophobic organic contaminants (HOCs) in the environment. This thesis aimed at addressing two key knowledge gaps in our understanding of how plants exchange HOCs with the atmosphere: (1) To improve our understanding of the uptake of HOCs into, and transfer through, leaves of different plant species which can significantly influence the transport and fate of HOCs in the environment; and (2) To evaluate an experimental approach to measure fluxes of HOCs in the field. The methods presented in papers I, II and III contribute to increasing our understanding of the fate and transport of HOCs in leaves by offering straightforward ways of measuring mass transfer coefficients through leaves and partition ratios of HOCs between leaves, leaf lipids and lipid standards and reference materials like water, air and olive oil. The passive dosing study in paper III in particular investigated the role of the composition of the organic matter extracted from leaves in determining the capacity of the leaves to hold chemicals and found no large differences between 7 different plant species, even though literature data on leaf/air partition ratios (Kleaf/air) varies over 1-3 orders of magnitude. In paper IV we demonstrated that the modified Bowen ratio method can be extended to measure fluxes of persistent organic pollutants (POPs) if the fluxes do not change direction over the course of the sampling period and are large enough to be measured. This approach thus makes it possible to measure fluxes of POPs that usually require sampling times of days to weeks to exceed method detection limits. The experimental methods described in this thesis have the potential to support improved parameterization of multimedia models, which can then be evaluated against fluxes measured in the field using the modified Bowen ratio approach. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>
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Sex determination and sex ratio distortion in the mosquito Aedes aegyptiTeo, Tze Min January 2010 (has links)
Aedes aegypti is one of the most important mosquito vectors of human disease, transmitting dengue, Chikungunya and yellow fever viruses. New control methods are much needed for this species and an ability to skew sex ratios toward males would be very useful for a number of strategies. In this study, male-specific chromosomal regions were searched for in Ae. aegypti using novel approaches such as microdissection of chromosomes. The sex determination pathway of Ae. aegypti was also explored, using Drosophila melanogaster as a model, to find candidate genes that could be used to induce male biased sex ratios. The transformer-2 (tra-2) gene is necessary for sexual differentiation of females in D. melanogaster, but its role remains unknown in mosquitoes. A homolog of tra-2 was identified in Ae. aegypti. Rapid Amplification of cDNA ends (RACE) experiments were conducted to characterize this gene in Ae. aegypti. The Ae. aegypti tra-2 gene, as for D. melanogaster, was highly variable in transcription due to alternative splicing and alternative polyadenylation, with 9 different variants identified. RNA interference (RNAi) was then used to determine if knockdown of all variants of Ae. aegypti tra-2 can be achieved and if it would cause gender switching in individuals, initially by means of direct injection of double stranded RNA, and then progressing to germline transformation. A construct designed to produce tra-2 dsRNA was injected into Ae. aegypti embryos and integrated into the Ae. aegypti genome. The transgenic population showed up to 100% male bias in single pair crosses. The male bias effect could still be seen in the heterozygous population. The results suggest that knockdown of tra-2 could provide a useful tool for sex ratio distortion as part of the development of novel control methods for Ae. aegypti.
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Piano QuintetTan, Chee-Tick 05 1900 (has links)
The thesis is a traditional piano quintet in the manner of Bartok, incorporating compositional techniques such as golden ratio and using folk materials. Special effects on strings are limited for easy conversion to wind instruments. The piece is about 15 minutes long.
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Local mate competition and the sex ratios of malaria parasites, with a focus on Plasmodium mexicanumNeal, Allison T. 01 January 2014 (has links)
Sex ratio theory is a focus in evolutionary biology that explores how natural selection shapes investment in males and females. It has provided some of the best quantitative evidence of evolution and could find utility in public health efforts through its application to malaria parasites. These parasites have distinct male and female forms that are produced following massive asexual replication, and they mate within the blood-feeding insects that transmit them between vertebrate hosts. A very similar population structure is assumed by local mate competition (LMC), a model from sex ratio theory that predicts female-biased sex ratios dependent on the degree of selfing within a mating patch.
In this dissertation, I test a series of predictions from LMC for the lizard malaria parasite Plasmodium mexicanum. These include: (i) sex ratios have heritable variation that is not constrained by other life history traits; (ii) single-genotype infections have female-biased sex ratios that are determined by male fecundity; (iii) multiple-genotype infections have less biased sex ratios than single genotype infections; (iv) if males are limiting, sex ratios may be less biased when there are fewer parasites present (an extension of LMC called fertility insurance); and (v) less biased sex ratios may also be favored if increased female production yields diminishing returns on transmission to a new vertebrate host. To test these predictions, I combined the study of natural and experimental infections, microscopy (parasite density and sex ratio), molecular genetics (infection genetic diversity), and mathematical modeling (of how transmission patterns might affect sex ratio evolution).
Overall, the results were qualitatively consistent with both LMC and my new model predictions. Sex ratios showed evidence of heritable variation that was unlinked to other life history traits measured. Sex ratios in single-genotype infections were female biased and consistent with the male fecundity observed, and were lower than sex ratios in experimental multiple-genotype infections, as predicted. Sex ratios were not less biased with lower sexual cell density, suggesting that males were not limiting. In fact, the opposite trend was sometimes observed: sex ratios were less biased with more sexual cells. This pattern has been observed previously in this and other species, and the only model that currently predicts such a trend is the new transmission model I outline.
This dissertation contributes to our understanding of sex ratio evolution for malaria parasites in a number of ways. First, it adds evidence to the idea that the selective forces implicated in LMC are at work in malaria parasites and that malaria parasites are able to detect and respond to relevant cues. Second, it helps account for discrepancies in existing data, which have often reached conflicting conclusions. Third, it offers one of the first detailed studies of malaria parasite male fecundity, an essential piece of the sex ratio puzzle. Finally, it outlines a new theoretical extension of LMC that provides novel predictions and highlights areas of study that may be fruitful for future work on malaria parasites and other organisms.
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Estimateurs de calage pour les quantilesHarms, Torsten January 2004 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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