Thesis (M.S.)--University of Michigan, 1950.

Thesis (M.S.)--University of Michigan, 1947.

Thesis--Universidade de Minas Gerais, 1960.

Thesis--Universidade de Minas Gerais, 1960.

The International Linear Collider (ILC) project aims at colliding electrons and positrons at an initial centre of mass energy of 500 GeV with high luminosity, and thus will allow scientists to probe new energy regimes. A general consensus within the accelerator physics and particle physics community has been made to utilise superconducting technology rather than normal conducting technology. A superconducting radio frequency (SRF) cavity will be used to accelerate bunches of particles to the design energy before delivering them to an interaction point. The major financial cost of the ILC lies in the area of the main linacs. These linacs consist of nine-cell cavities and are based on the TESLA design. An option being considered to reduce the overall footprint and project cost is to enhance the cavity gradient. This research concerns itself with my new cavity design with a view to reaching higher gradients. This design is focussed on minimising the surface electromagnetic fields and maximising the bandwidth of the accelerating mode. This new shape, which is referred to as the New Low Surface Field (NLSF) design, bears a similarity to the current Ichiro and Reentrant designs. A design of a complete nine-cell cavity, including power couplers and higher order mode damping couplers is presented. An equivalent circuit model theory is applied to represent the radio frequency (rf) mode properties of the cavity for both the fundamental accelerating mode and higher order modes. This represents an almost complete design, including HOM damping, for a unique high gradient superconducting cavity.

No description available.

No description available.

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No description available.

A research report submitted to the faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in the partial fulfillment of the requirements for the Degree of Master of Science in Dentistry, Johannesburg, 2017 / Chemotherapy and radiation therapy are the most widely used interventions for the treatment of cancer. Several adverse effects including mucositis are associated with these therapies, which affect a patient’s quality of life, resulting in morbidity and mortality. Cancer therapy also causes an imbalance in the oral flora which allows colonization of the oral cavity with uncommon bacteria, including aerobic gram negative bacteria and less commonly, Candida. These organisms can become established in the lesions of oral mucositis. These gram negative bacteria produce endotoxins. Although the involvement of endotoxins in the development of systemic infections is well described, the role of endotoxins in oral mucositis is not known. Therefore, this study investigated the presence of aerobic gram negative bacteria and endotoxins in the oral cavities of patients receiving cancer treatment and their role in the development of oral mucositis. Oral cavity rinse samples were collected from 100 cancer patients on cancer treatment and 50 healthy individuals. Ethical clearance was obtained from The Committee for Research on Human Subjects (Medical). The demographic and clinical data were recorded. Samples were serially diluted and cultured onto Mitis Salivarius Agar for Streptococci, Baird Parker Agar for Staphylococcus aureus, MacConkey Agar for aerobic gram negative bacteria (AGNB) and Chromagar for Candida species. Colony counts were obtained and the cultures of AGNB and Candida species were further identified at the species level using the API technique. An antimicrobial susceptibility test was performed on AGNB. Oral rinse samples were further tested for the presence of endotoxin using the Hycult Biotech Limulus Amebocyte Lysate (LAL) assay. Results were analysed using the Mann-Whitney and chi-square test. P-values of ≤ 0.05% were considered significant. Eighty percent of cancer patients were females with breast (58%) or cervical cancer (9%). The majority of these patients were on chemotherapy (61%), were receiving a combination of chemotherapeutic drugs and had completed many cycles of chemotherapy treatment. Twelve percent of patients had oral mucositis of various grades. Healthy individuals also comprised of mainly females (76%). All cancer patients and 98% of healthy individuals carried Streptococci. No significant difference in the carriage of S. aureus was found between the two groups. However, the Candida carrier rate was significantly high in cancer patients (55%) compared to the healthy (20%) individuals (p<0.01). Although the Candida counts were not different between the groups (p>0.05), cancer patients carried a variety of Candida species and some patients carried more than one type of Candida species in their oral cavity. In addition, C. glabrata was only found in cancer patients. Between the groups of cancer patients and healthy individuals, no significant difference in the carrier rate of AGNB was found (cancer 24% vs 14% healthy). However, cancer patients carried a variety of AGNB. Enterobacter cloacae and Klebsiella pneumonia was isolated from the oral cavities of both the study groups. These bacteria were resistant to many antibiotics. When the prevalence of these oral bacteria was compared between patients with and without oral mucositis, it was found that the percentage prevalence of Candida species was significantly high in patients with oral mucositis. A mean endotoxin concentration of 3.65ng/ml and 3.37ng/ml was detected in the oral rinse samples of cancer patients and healthy individuals respectively. The difference in the endotoxin between the two groups was not significant (p=0.5). Mean values of 4.1ng/ml and 3.53ng/ml were found in cancer patients with and without oral mucositis respectively. The difference in the quantities of endotoxins between the two groups was not significant (p=0.6). In addition, endotoxin present in cancer patients with AGNB (3.39ng/ml) and without AGNB (3.8ng/ml) was also not significantly different. These results suggest that although cancer patients carry aerobic gram negative bacteria and endotoxins in their oral cavities, they may not contribute in the exacerbation of oral mucositis. However, Candida species may contribute in the exacerbation of oral mucositis and therefore, during cancer treatment, it is important to take preventative measures to reduce the colonization of Candida to prevent infection. / MT2017