Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The Universal Classifier Synchronizer (UCS) is a Cognitive Radio system/sensor that can detect, classify, and extract the relevant parameters from a received signal to establish physical layer communications using the received signal's profile. The current implementation is able to identify signals including AM, FM, MPSK, QAM, MFSK, and OFDM. The system is constructed to run on a Universal Software Radio Peripheral (USRP) with the GNU Radio software toolkit and also runs on an Anritsu™ signal analyzer. In both prototypes, the UCS system runs on a host computer's General Purpose Processor (GPP) and is constructed in Matlab™. The aim is to then create a portable and standalone version of the UCS system as an intermediate step towards building a future commercial implementation. This application and particular implementation aims to run on a Lyrtech SFF SDR platform and uses its FPGA and DSP modules for implementation. This platform is one of the more advanced SDR platforms available, and the aim is to develop parts of the UCS system to run on this platform. The aim is to eventually develop the complete UCS cognitive radio system on the Lyrtech SFF SDR platform that can act as a standalone portable cognitive radio system. The modules created and implanted/implemented on the SDR hardware are the Bandwidth Estimation, and Symbol Timing & Coarse Classification modules. This is the system decision path towards classification, synchronization, and demodulation of digital phase modulated signals (QAM and MPSK signal types) and also analog signals. The Digital Receiver Module (DRM) is implemented on the FPGA and takes care of all the digital down conversions, mixing, decimation, and low pass filtering. The FPGA is connected to the DSP module via a bus subsystem where the DSP receives real-time base-band complex IQ samples for further signal processing. The main UCS algorithm runs on the platform's DSP and is compiled from executable embedded C-code. Therefore, this system can then be implemented on virtually any setup that has an RF front end, digital receiver module, and processing module that will execute floating and fixed point C-code with minor changes. / Master of Science

This research developed two innovative test methods that were used to experimentally evaluate the performance of a novel blade tip timing (BTT) system from Prime Photonics, LC. The research focused on creating known blade tip offsets and tip vibrations so that the results from a BTT system can be validated. The topic of validation is important to the BTT field as the results between many commercial systems still are not consistent. While the system that was tested is still in development and final validation is not complete, the blade tip offset and vibration frequency validation results show that this BTT system will be a valuable addition to turbomachinery research and development programs once completed. For the first test method custom rotors were created with specified blade tip offsets. For the blade tip offset alternate measurement, the rotors were optically scanned and analyzed in CAD software with a tip location uncertainty of 0.1 mm. The BTT system agreed with the scanned results to within 0.13 mm. Tests were also conducted to ensure that the BTT system identified and indexed the blades properly. The second developed test method used an instrumented piezoelectric blade to create known dynamic deflections. The active vibration rotor was able to create measureable deflection over a range of frequencies centered on the first bending mode of the blade. The results for the 110 Hz, 150 Hz, 180 Hz first bending resonance, 200 Hz, and 1036 Hz second bending resonance cases are presented. A strain gage and piezoelectric sensor were attached to the active blade during the dynamic deflection tests to provide an alternate method for determining blade vibration frequency. The BTT system correctly identified the active blade excitation frequencies as well as a 120 Hz frequency from the drive motor. This thesis also explored applying BTT methods and testing to more realistic blade geometry and vibration. Blade vibrations are usually classified by their frequency relative to the rotation speed. Synchronous vibrations are integer multiples of the rotational speed and are often excited by struts or vanes fixed to the engine case. For this reason, special probe placement algorithms were explored that use sine curve fitting to optimize the probe placement. Knowing how the blade will vibrate at operation before testing is critical as well. In preparation for future research, ANSYS Mechanical was used to predict the first three modes of a PT6A-28 first stage rotor blade at 1,966, 5,539, and 7,144 Hz. These frequencies were validated to within 4% using scanning laser vibrometry. The simulation was repeated at speed to produce a Campbell Diagram to highlight synchronous excitation crossings. / Master of Science

Introduction: People with Parkinson's disease require individualised medication regimens to achieve symptomatic control whilst managing complications of the treatments and the underlying disease. Patients should continue to receive their individualised regimen when they are admitted to hospital but studies have highlighted that this may not happen. There is a paucity of research about patients' perceptions of the management of anti-parkinsonian medicines during a hospital admission and the aim of this study was to explore the perceptions of Parkinson's disease patients admitted to Leeds Teaching Hospitals about the management of their anti-parkinsonian medications.Method: Grounded theory methodology was used to allow detailed exploration of patients' perceptions and to generate theory about this under-researched area. Face to face, semi-structured interviews were conducted with 13 Parkinson's disease patients during their hospital admission, fully transcribed and analysed using the constant comparative approach. Results: Categories contributing to the core category of 'patient anxiety' were identified as 'maintaining usual medication routine', 'access to anti-parkinsonian medications', 'accuracy and consistency', 'trust in healthcare professionals' and 'staff knowledge about Parkinson's disease'. Strategies used to manage the anxiety were related to the categories 'utilising expertise' in Parkinson's disease and 'patient involvement' in their care. Discussion: The theory suggests that some patients have negative perceptions about the management of their medicines during a hospital admission. Areas for practice development are presented along with areas for future research. Conclusion: This study provides new insight into the perceptions of patients with Parkinson's disease about the management of their medicines during a hospital admission.

The experiments described in this thesis use psychophysical techniques and human observers to investigate temporal processing in the millisecond range. The thesis contains five main sections. Introductory chapters provide a brief overview of the visual and auditory systems, before detailing our current understanding of duration processing. During the course of this review, several important questions are highlighted. The experiments detailed in Chapters 8-11 seek to address these questions using the psychophysical techniques outlined in Chapter 7. The results of these experiments increase our understanding of duration perception in several areas. Firstly, Experiments 1 and 2 (Chapter 8) highlight the role of low level stimulus features: even when equated for visibility stimuli of differing spatial frequency have different perceived durations. Secondly, a psychophysical hypothesis arising from the ¿duration channels¿ or ¿labelled lines¿ model of duration perception is given strong support by the adaptation experiments detailed in Chapter 9 and 10. Specifically, adaptation to durations of a fixed temporal extent induces repulsive duration aftereffects that are sensory specific and bandwidth limited around the adapted duration. Finally Chapter 11 describes the results of experiments designed to probe the processing hierarchy within duration perception by measuring the interdependency of illusions generated via duration adaptation and via multisensory cue combination. The results of these experiments demonstrate that duration adaptation is a relatively early component of temporal processing and is likely to be sub served by duration selective neurons situated in early sections of the visual and auditory systems.

This thesis explores the effects of three important factors on a firm's investment and financing decisions, using contingent claim structural model. The first essay investigates how implementation lag impacts investment timing for a levered firm. The main finding is that implementation lag can potentially have a substantial effect on a company’s investment trigger. A crucial determinant of the lag-investment relationship is the fraction of investment cost that has to be incurred upfront. If this fraction is small, investment trigger is a decreasing function of implementation lag and the effect can be economically significant. If this fraction is large, investment trigger can be either increasing or decreasing in lag, but the magnitude of the effect is not large. The second essay investigates how future uncertain growth opportunity impacts a firm's investment timing decision and optimal leverage ratio. The firm has an option to expand profits after the first investment. However, the exercise of the growth option depends not only on the underlying profit flow but also on the uncertain arrival of the growth opportunity. The model illustrates that such uncertainty can significantly impact the initial investment timing for unlevered firm in a non-monotonic way. For levered firm, the future growth uncertainty, along with debt overhang problem, can shape the firm’s financing decision at initial investment. The third essay shows how risk-compensating performance-sensitive debt can be used to mitigate the “overinvestment” agency problem. We show that properly designed performance-sensitive debt can add significant value relative to fixed-coupon debt, and identify the risk-compensation level that maximizes shareholder wealth. The optimal risk-compensation level is found to be smaller than that required to eliminate overinvestment; thus, it is optimal for shareholders to incur some agency cost of overinvestment. / Thesis / Doctor of Philosophy (PhD)

Pattern formation ensures that tissues, organs, and structures develop in the correct place and orientation within the body. Patterning processes are at the heart of morphogenesis yet remain poorly understood due to their complexity. The sea urchin larval skeleton provides a simple model to study skeletal patterning, where the skeleton-producing primary mesenchyme cells (PMCs) receive patterning cues from the overlying ectoderm. The normal skeletal patterning process requires the PMCs to migrate within the blastocoel to specific positions. While ectodermal and endodermal signals regulate PMC positioning and differentiation, additional signals act to regulate biomineralization per se in the PMCs. However, the distinction between these effects is not well understood and new efforts have been made to identify these patterning and biomineralization cues that regulate sea urchin skeletal development. Understanding the mechanism by which PMCs interpret and transduce patterning cues into a migratory bias and/or positional information will provide insight into tissue patterning and developmental plasticity both in sea urchins and, more broadly, in deuterostomes. Ethanol is a known vertebrate teratogen that causes craniofacial defects as a component of fetal alcohol syndrome. Perturbations to retinoic acid biosynthesis and the Hedgehog signaling pathway are thought to be causal for the fetal alcohol syndrome phenotype in vertebrates. We used the sea urchin embryo to gain evolutionary insight into how ethanol affects embryonic development in a basal deuterostome animal. We found that ethanol specifically perturbs skeletal patterning. When sea urchin embryos are exposed to ethanol, they exhibit conspicuously delayed development, and broad skeletal patterning defects that are potentially analogous to fetal alcohol syndrome associated facial patterning defects in vertebrates and humans. PMC transplantation experiments demonstrated that ethanol-induced defects are not specific to the PMCs, and instead reflect the perturbation of patterning cues. We also found that the expression of both patterning cues and PMC-specific genes was delayed by ethanol exposure. Surprisingly, our results indicate that retinoic acid and Hedgehog pathways are not functionally relevant for the teratogenic effects of ethanol in the larval skeletal patterning process, indicating a lack of evolutionary conservation of these pathways in ethanol-mediated teratogenesis among deuterostomes. Temporal transcriptome analysis revealed significant impacts of ethanol on signaling and metabolic gene expression and a disruption in the timing of expression for sea urchin specification gene regulatory network (GRN) genes. Surprisingly, multiple circuits with the GRN exhibit precocious expression while others are delayed. Taken together, our results suggest that the skeletal patterning perturbations in ethanol-treated sea urchin embryos arise from a loss of temporal synchrony within and between the instructive and responsive tissues during pattern formation.

Research was conducted in 2014 to evaluate the efficacy of harvest-aid systems and the performance of harvest aids applied at various timings in Mid-South soybean production. Evaluations included yield, desiccation, green stems and pods, and seed quality. Saflufenacil did not perform as well as the producer standard 14 DAT at the Starkville, MS location with desiccation levels of 78 and 98%, respectively. However, similar performance was observed 14 DAT at the Brooksville, MS location. When applied at R6.5, paraquat based treatments improved desiccation and reduced green stem 7 DAT compared to other treatments. No yield differences were observed between harvest aid treatments. However, yield differences were observed between the R6.0 and R6.5 timings. These data suggest saflufenacil is an effective harvest aid option, but may require up to 14 days for optimum desiccation. In addition, yield is not impacted by harvest aid product, but rather the timing of the application.

Research was conducted at the Mississippi State University Delta Research and Extension Center from 2015 to 2018 to (1) determine the effects of sub-lethal concentrations of paraquat, metribuzin, fomesafen, and cloransulam-methyl applied at different rice growth stages, determine the effects on rice growth of simulated off-target paraquat applications at varying concentration based on a proportionally decreased carrier volume characterize rice response to a sub-lethal concentration of paraquat in combination with common POST and residual herbicides, assess whether starter N fertilizer or different N fertilizer management strategies can aide in rice recover after exposure to a sub-lethal concentration of paraquat, and define a maximum soil concentration of S-metolachlor that will allow rice to germinate and emerge. Rice yield was negatively affected following exposure to paraquat applied any time after rice emergence. Paraquat applications to rice in early reproductive growth reduced rough rice yield and seed germination the greatest. Paraquat plus metribuzin injured rice 68 to 69% 14 and 28 d after treatment (DAT), which was 10 to 13% greater than following paraquat alone or paraquat plus fomesafen. Pooled across metribuzin and fomesafen treatments, paraquat reduced rough rice yields 23%. Paraquat plus 10 different residual herbicides injured rice ≥51% 28 DAT and reduced rough rice yields ≥21%. In spite of starter N fertilizer applications, paraquat injured rice ≥41%, reduced height 57%, reduced dry weight prior to flooding 77%, delayed maturity 10 d, reduced dry weight at maturity 33%, and reduced rough rice yield 35%. Similar results were observed in the N Fertilizer Timing Study. Soil concentrations of s-metolachlor 28 DAT were 30, 31, 32, 36, 61, and 488 ppm following exposure to s-metolachlor applied at 0, 1/64, 1/32, 1/16, 1/4, and 1X concentration. A soil analysis would be the best option to determine levels of s-metolachlor prior to planting rice if an off-target herbicide movement containing s-metolachlor occurred. These data indicate that paraquat can have negative impact on rice growth and development. Therefore, it is crucial that if environmental conditions are conducive for off-target herbicide movement extreme caution should be exercised when applying paraquat adjacent to fields devoted to rice production.

This thesis presents a series of human psychophysical experiments designed to examine the interaction between the reliability of spatial form information and the neural mechanisms responsible for the processing of sub-second durations. Duration discrimination sensitivity was found to be lower when event durations were defined by stimulus characteristics that caused reductions in spatial form sensitivity. This form-duration sensitivity coupling persisted across stimuli defined both by crossed and uncrossed retinal disparity and within monocularly visible texture-defined stimuli. The interaction was also observed when spatial form was degraded by physical instability within shape borders, and when physically stable borders became perceptually unstable. These effects could not be attributed to artefacts of stimulus visibility, temporal coherence or stimulus size. Adaptation experiments generated aftereffects of perceived duration within stimuli whose durations were defined solely by retinal disparity, providing the first demonstration of duration selectivity within exclusively cortical duration encoding mechanisms. The selectivity of these aftereffects was then investigated using adapting and testing durations defined by matching or opposing retinal disparities. Duration aftereffects were maximal when adapt and test disparities were matched. However, there was partial transfer of duration aftereffects across large changes in retinal disparity, implicating contributions from higher-level extra-striate mechanisms. Collectively, these experiments provide support for duration processing mechanisms that are inextricably linked to the mechanisms underpinning spatial processing across multiple levels of the visuo-spatial hierarchy.