Ray tracing applications for high-frequency radar: characterizing artificial layers and background density perturbations in the ionosphere

Thesis (M.S.) University of Alaska Fairbanks, 2012In this thesis a numerical method of calculating ground-scattered power from the results of a ray tracing analysis is presented. The method is based on a conservation of energy approach and offers advantages over an alternative method derived from the radar equation. The improved numerical method is used to investigate two different physical phenomena by comparison with measured ground-scattered power observed by a high-frequency (HF) radar located in Kodiak, AK that is part of the Super Dual Auroral Radar Network (SuperDARN). First, the effects of artificial electron density layers on observed ground scatter is studied through a comparison of simulated and measured power profiles. The results demonstrate that the location and spatial dimensions of artificial layers may be estimated by a comparison of the location and amplitude of simulated and measured power enhancements. Second, a Monte-Carlo simulation method is used to characterize the temporal distribution of ground-scattered power. Random processes including background electron density perturbations, polarization, noise, and sample correlation are modeled in simulation and used to estimate statistical moment profiles. The simulated statistical moment profiles are compared to measured profiles as a means of model verification and to roughly approximate background electron density perturbations in the ionosphere

A Study of the Root Rot-Nematode Complex and the Comparative Yield of 17 Varieties of Alfalfa in Washington County, Utah

Alfalfa is the major forage crop in the state of Utah. It is especially important in Washington County where mild temperatures allow the production of 4 to 5 cuttings each year, and where the dairy industry is increasing

INVESTIGATING THE EFFECTS OF OROPHARYNGEAL SENSORY STIMULATION ON SWALLOWING

This series of studies examined the effects of oropharyngeal air-pulse stimulation on saliva swallowing. The first study sought to determine whether air-pulse trains delivered to the peritonsillar area facilitate swallowing in healthy young adult subjects. Trains of unilateral, or bilateral, air pulses were delivered to the peritonsillar area while swallows were simultaneously identified from their associated laryngeal and respiratory movements. Results in four subjects indicated that oropharyngeal air-pulse stimulation evoked an irrepressible urge to swallow, followed by an overt swallow as verified by laryngeal and respiratory movements. In addition, air-pulse stimulation was associated with a significant increase in saliva swallowing frequency. The second experiment examined the effects of oropharyngeal air-pulse stimulation on saliva swallowing in healthy older adults. Saliva swallowing rates were monitored across six conditions: baseline without mouthpiece, baseline with mouthpiece in situ, unilateral right oropharyngeal stimulation, unilateral left oropharyngeal stimulation, bilateral oropharyngeal stimulation, and sham stimulation. Results indicated that the bilateral oropharyngeal air-pulse stimulation condition was associated with a statistically significant increase in mean saliva swallowing rate compared to the baseline without mouthpiece, baseline with mouthpiece in situ, and sham stimulation conditions. In contrast to the perception by young adults of an irrepressible urge to swallow in response to oropharyngeal air-pulse delivery, the older adults did not perceive the air­ pulse stimulation as being associated with swallowing or other percept. These findings suggest that the facilitatory effect of oropharyngeal air-pulse stimulation on saliva swallowing may be robust across the adult age span. iii The third study evaluated the effects of oropharyngeal air-pulse stimulation on saliva swallowing frequency in hemispheric stroke using a single-subject research design. Visual analysis indicated that four of the eight subjects demonstrated increased saliva swallowing rates in association with bilateral oropharyngeal stimulation compared to baseline saliva swallowing rates. Descriptive analysis of subject demographics was conducted to identify participant and stroke-related features related to various air-pulse response patterns. Future research is required to elucidate the swallowing impairment profiles for which oropharyngeal air-pulse stimulation affects swallowing, and to determine whether oropharyngeal air-pulse stimulation can enhance recovery of swallowing function secondary to hemispheric stroke

Successful Negotiations: A Phenomenological Study of the Lived Experiences of Superintendents Who Successfully Negotiate Teacher Contracts

New York State has a long history related to teachers’ unions. Superintendents are often the main players for school districts when negotiating teachers’ contracts. While much has been researched about negotiations, there is a gap in the literature in relation to the motivating factors of superintendents to successfully negotiate teachers’ contracts. The purpose of this transcendental phenomenological study was to describe the lived experiences of school superintendents who have successfully negotiated teachers’ contracts within suburban areas of New York State. The central research question was: What are the lived experiences of school superintendents who have successfully negotiated teachers’ contracts in public school districts in suburban New York? Sub-questions explored motivations, external factors, and internal or personal characteristics of the superintendents who have lived experience. The theories guiding this study included the negotiation theory (Zartman, 1978) and the self-determination theory (Deci & Ryan, 2000b). The methodology that was utilized was a transcendental phenomenological design that includes purposeful sampling of participants, data collection obtained through questionnaires, interviews, and document analysis for 11 participants. Data analysis utilized Moustakas’ (1994) prescribed procedures for constructing thematic portrayals of the lived experiences of the participants. When the data were analyzed, four themes emerged: negotiations processes, opportunities of negotiating, obstacles of negotiating, and effectuation of success. Results described the lived experiences of superintendents and how these experiences play a role in administration, with teachers’ unions and within the community