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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

Persistence of a Single Phytoplankton Species in a Water Column with Time-Periodic Light Intensity

Lee, Russell B. January 2021 (has links)
No description available.
252

An Analysis of Energy Intensities in the Manufacturing and Service Sectors in Canada

Robertson, Heather 04 1900 (has links)
<p> With fluctuations in energy price and the uncertainty of energy supply, particularly in the past decade, it has become increasingly important to forecast energy requirements. It is useful to know the response of energy demand to changes in both energy price and supply. In addition, the amount of substitution possibilities would allow forecasting demand for individual energy types. </p> <p> This study focuses on changes in energy intensities in the manufacturing and service sectors from 1962 to 1982. Trends for the sectors as a whole, and individual industries within each sector are analyzed on the basis of significant changes in; total consumption patterns and specific energy types. These trends are helpful in acting as a base for analyzing future energy needs in Canada. </p> / Thesis / Bachelor of Arts (BA)
253

The Impact of Counter-Rumor Strategy and Source on Non-Professional Investors' Judgments over Social Media

Li, Ziyin 08 1900 (has links)
Non-professional investors often rely on information obtained from social media to make investment decisions. Extant literature has not examined the most effective strategy for the target company to counter the rumors so that investors will be more willing to continue investing in the target firm. Drawing on source credibility theory and the moral intensity model, I propose that the most effective strategy would vary given different agents who are selected to counter the rumor. After conducting a 2 x 3 (counter-rumor source x counter-rumor strategy) experiment with 272 non-professional investors recruited from Amazon Mechanical Turk, my study shows that when an internal agent (e.g., the CEO) acts as a counter-rumor source, shareholders are more willing to invest in the company when the internal agent utilizes a denial strategy rather than a reassociation or a questioning strategy. In contrast, when an external agent (e.g., a famous food blogger) serves as the counter-rumor source, the external agent can also use a questioning strategy in addition to a denial strategy to motivate shareholders to be more willing to invest in the company; however, the external agent still needs to avoid from engaging a reassociation strategy. Moderated serial-mediation analysis shows that the persuasiveness of the counter-rumor information and investors' perceived rumor intensity serially mediate the effect of counter-rumor source on investors' willingness to invest, and this effect is conditioned on the different strategy used to counter the rumor. Overall, the main effect of counter-rumor source suggests that external agents are perceived as more persuasive, which leads investors to perceive less rumor intensity, making them more willing to invest in the target company. The results of my paper can thus inform companies' social media policy.
254

Mechanical High-Intensity Focused Ultrasound (Histotripsy) in Dogs with Spontaneously Occurring Soft Tissue Sarcomas

Yang, Ester 06 September 2023 (has links)
Background: Histotripsy is a non-thermal, non-invasive high-intensity focused ultrasound (HIFU) ablative technique that causes mechanical fragmentation of tissue, resulting in liquefied acellular debris with histologically clear demarcated boundaries between treated and non-treated tissues. The acellular debris may include tumor antigens with preserved immunogenicity and the potential to generate systemic immune response against tumor cells. Soft tissue sarcomas (STS) are a common form of cancer in dogs with biological behavior similar to STS in humans. Long-term tumor control requires complete removal with extensive surgical resection, which in many cases is not feasible. As a result, there is need for alternative therapies. Objectives: The primary objective of this study was to demonstrate safety and feasibility of histotripsy in a small animal model of spontaneous STS. The secondary objective was to characterize the impact of histotripsy on the immunologic response. Materials and methods: Pet dogs diagnosed with spontaneous STS were recruited. CT scan of the chest, abdomen, and the tumor was performed for staging and treatment planning. Pretreatment biopsies were obtained. Safety was monitored with physical examinations, owner reports, and CBC/serum biochemistry. Partial tumor ablation was performed using a 500 kHz prototype histotripsy system. A spherical treatment zone of up to 3 cm diameter in each tumor was treated with histotripsy according to the patient-specific treatment plan using 1-2 cycle pulses applied at a pulse repetition frequency (PRF) of 500 Hz. Anatomical ablation zones were evaluated with contrast CT at 1- and 4-days post-treatment, with tumor resection at 4-6 days post-treatment. Tumor microenvironment (TME) gene expression was evaluated with the Nanostring Canine IO panel, and the systemic immune response was evaluated using multiplex serum cytokine levels. Results: Ten dogs were recruited and treated. Tumor histologies included 3 grade III STS, 4 grade II STS, 2 grade I STS, and 1 malignant mesenchymoma. Six dogs were alive, three dogs were euthanized due to disease progression, and one dog was lost to follow up. Histotripsy-related complications were generally self-limiting, with only one patient having increased cutaneous injury score from 1 to 2 (scale 1-5) post-treatment, likely due to prefocal cavitation at the skin. No significant adverse events impacting patient outcome were noted in any of the patients. Visible histotripsy cavitation bubble clouds were seen on real-time ultrasound imaging in nine of ten treatments. Post-treatment histopathology indicated sharply defined regions of ablation that were clearly identifiable grossly and histologically in all samples. Treatment zones were characterized by loss of cell viability, hyalinization, and acute hemorrhage. Post-treatment contrast-enhanced CT images revealed clear, demarcated regions of histotripsy ablated tissue in seven of ten patients. Differential gene expression analysis identified 79 genes with at least 2-fold change following treatment. Genes associated with inflammation, immune cell migration, and immune cell interactions were the highest upregulated. Amongst the gene set analyses, the myeloid compartment gene sets obtained the highest significance score. There were no statistically significant differences between pre- and post-treatment cytokine concentrations for any of the analytes. Conclusions: Histotripsy can achieve safe and effective tumor ablation in dogs diagnosed with STS. Histotripsy induced pro-inflammatory changes within the tumor microenvironment. Histotripsy as an immunotherapeutic treatment option needs to be further investigated. Histotripsy has a potential to be a precise, non-invasive treatment for canine STS. / Master of Science / Histotripsy is a non-thermal high-intensity focused ultrasound (HIFU) ablative technique that uses controlled acoustic cavitation to cause mechanical fragmentation of tissue. To date, there are no reports investigating histotripsy for the treatment of soft tissue sarcoma (STS). This study aimed to investigate the in vivo feasibility of ablating STS with histotripsy and to characterize the impact of partial histotripsy ablation on the acute immunologic response in canine patients with spontaneous STS. CT of the chest, abdomen, and the tumor was performed for staging and treatment-planning. Pretreatment biopsies were obtained. Safety was monitored with physical examinations, through owner reports, and CBC/serum biochemistry. A custom 500 kHz histotripsy system was used to treat ten dogs with naturally occurring STS. Anatomical ablation zones were evaluated with contrast CT at 1- and 4-days post-treatment, with tumor resection at 4-days post-treatment. Safety was determined by monitoring vital signs during treatment and post-treatment physical examinations, routine lab work, and owners' reports. Ablation was characterized using radiologic and histopathologic analyses. Systemic immunological impact was evaluated by measuring changes in cytokine concentrations, and tumor microenvironment changes were evaluated by characterizing changes in infiltration with tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs) using multiplex immunohistochemistry and differential gene expression. Results showed histotripsy ablation can achieve safe and effective tumor ablation in all ten dogs. Immunological results showed histotripsy induced pro-inflammatory changes in the tumor microenvironment. Histotripsy as an immunotherapeutic treatment option needs to be further investigated. Overall, this study demonstrates histotripsy's potential as a precise, non-invasive treatment for STS.
255

Fatigue Crack Growth Under Residual Stresses Around Holes

Nagaralu, Ramesh 10 December 2005 (has links)
Compressive residual stresses induced by tensile overloads, compressive under loads, or by a cold-expansion process in specimens containing a circular hole and their influence on subsequent fatigue crack growth in aluminum alloys are studied. The finite element method is used to calculate residual stresses. The superposition method, which uses crack-tip stress intensity factors for cases involving remote loading and residual stresses, is used to calculate crack growth life for three kinds of tests from the literature: (1) fatigue of a circular hole specimen after an overload or under load, (2) single crack growing from a circular hole after a severe tensile overload, and (3) single crack growing from a circular hole after cold-working, reaming and notching. All specimens were subjected to subsequent constant amplitude loading. The superposition method worked fairly well for most cases, but tended to over predict fatigue life for small cracks and for cracks growing under residual stresses, which produce compressive (maximum and minimum) stress intensity factors.
256

An Archaeological Investigation of Four Woodland-period Sites in the North Central Hills Physiographic Region of Mississippi

Parrish, Jason Lee 05 August 2006 (has links)
Woodland-period archaeological sites in the North Central Hills physiographic region of Mississippi appear to be highly variable in occupation size, site function, duration, and occupational intensity. To better understand the occupational history and settlement patterns of such sites, several characteristics of four Woodland-period sites located within the Tombigbee National Forest, Ackerman Unit, Mississippi, are evaluated and compared to a larger, previously investigated site, 22WI516. From the data obtained in the field and laboratory, a determination of the causes of the variability among Woodland-period sites in the study area is attempted. Physiographic constraints appear to underlie much of the variability presented by the archaeological record.
257

Vector Intensity and Holography-Based Acoustic Source Characterization of a Military Jet Aircraft

Stout, Trevor Alden 01 July 2015 (has links)
The scientific community has employed multiple methods to analyze and describe the jet noise emanating from the turbulent exhaust flow from modern military aircraft engines, with the goal that better characterization of the sound radiation will improve noise reduction efforts. This thesis utilizes three different approaches to characterize the noise source region from a static F-22A Raptor. First, the energy flow field along planes near the aircraft and along an arc is measured using a multidimensional vector intensity probe. The resulting vector intensity maps give a clear indication of the directionality of the noise as a function of frequency at different engine conditions. A straightforward ray-tracing method show the utility of vector intensity measurements in source characterization by estimating the region from which the loudest portions of sound are emanating. Second, intensity reconstructions from near-field acoustical holography (NAH) provide an estimate of the three-dimensional radiated energy flow field. The sound field is shown to be dominated by mutually incoherent radiation lobes, which can be partially isolated by a partial decomposition method. Lastly, a wavepacket source model is optimized in light of amplitude-based NAH reconstructions near the jet axis. The wavepacket model successfully fits the NAH-reconstructed partial fields, especially at frequencies above 50 Hz, indicating that the source may be modeled by multiple wave packets at each frequency.
258

Intensity Auto- and Cross-Correlations and Other Properties of a <sup>85</sup>Rb Atom Coupled to a Driven, Damped Two-Mode Optical Cavity

Hemphill, Patrick A. 24 July 2009 (has links)
No description available.
259

The Effects of Land Cover Type on Tornado Intensity in the Southeastern U.S.

Butler, Kelly M. 14 September 2017 (has links)
No description available.
260

The Effect of Creatine Supplementation on Exercise Performance following a Short-term Low Carbohydrate Diet

Born, Stephanie Ann 18 October 2017 (has links)
No description available.

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