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The secant method is applied to an iterative algorithm of electromagnetic scattering from planar surfaces with periodic structure. The theory of convergent solutions for iterative techniques is discussed and examined. The Secant method is applied to the spectral iteration approach to accelerate and assure convergence of the basic iterative scheme. The derivation of the method as applied to surfaces containing parallel thin wire gratings is presented, and the conditions for achieving convergence are explored. This new method is also applied to gratings made of coated wires. The reflection characteristics of the grating as a function of wire spacing, wire conductivity, and polarization of the incident field are computed, and the results are compared with those of previous works. Suggestions and recommendations for applying the method to more complicated structures are also included.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23740号 / 理博第4830号 / 新制||理||1691(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 鹿内 利治, 教授 松下 智直, 准教授 竹中 瑞樹 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Cucurbita maxima and Cucurbita andreana are closely related species; however, the calcium phytate levels of the Cucurbita seeds differ significantly. Hybridization of the two Cucurbita species is difficult to achieve. The aim of my research was to extensively study the structure of C. maxima and C. andreana pollen and determine whether the pollen of the species differed in their elemental content. This thesis entails the most comprehensive study of the structure, chemical composition and elemental content of the pollen from a dicot plant. This study of Cucurbita pollen required the use of various light microscopy, electron microscopy and elemental analyses techniques. Histochemical stains revealed information about the chemical structure of pollen and pollen storage reserves. The primary storage reserve of Cucurbita pollen consisted of starch. Additional storage reserves consisted of protein, small amounts of lipids and mineral reserves. Additional studies of the external and internal structures of the Cucurbita pollen were carried out with transmission electron microscopy and scanning electron microscopy respectively. Preparation of sections of pollen for electron microscopy was difficult. Sectioning problems arose due to the thick pollen wall, the density of pollen cytoplasm, and inadequate infiltration of epoxy resin into pollen during processing. C. maxima and C. andreana pollen grains were fixed anhydrously because water-soluble phytates such as potassium phytate are extracted by aqueous fixatives . The cytoplasm of both species contained many small electron-dense globoid particles. Globoid particles were observed in sections of pollen and in samples of ground pollen. Elemental analysis of globoid particles from Cucurbita pollen was carried out, for the first time, with energy dispersive X-ray (EDX) analysis. EDX analysis spectra of globoid particles from C. maxima and C. andreana pollen were compared. Spectra of Cucurbita pollen globoid particles were similar to spectra from phytate deposits in seeds. EDX analysis of globoid particles of pollen revealed that the globoid particles contained mainly Mg, P and K. EDX analysis spectra of globoid particles of sections of Cucurbita pollen revealed that water soluble materials, likely K phytate, were extracted from sections cut onto water-filled microtome boats. Pollen sections cut onto absolute ethanol-filled microtome boats experienced less extraction of water soluble materials from the sections. Neutron activation analysis of whole pollen grains revealed that the individual concentrations of Mg, K, Ca and P were not significantly different from species to species. The elemental analyses results strongly suggest that phytate is stored in globoid particles of Cucurbita pollen. / Thesis / Master of Science (MS)

Recent advances in immunological technology have made it feasible to investigate the diagnosis and treatment of cancer with radiolabelled anti-tumor antibodies. The red bone marrow and endosteal cells of bone are likely to be the dose limiting tissues for systemic applications. Therefore, it is of clinical importance to quantitate their dose. Due to the small size of the marrow cavities in trabecular bone, it is experimentally difficult to measure the electron dose distribution. A computer simulation of electron transport is used to determine the dose distribution inside the marrow cavity. Electrons are backscattered more from bone than soft tissue, thereby increasing the dose to the radiosensitive endosteum and red bone marrow. A point source of beta activity (204Tl and 147pm) sandwiched between planar slabs of bone and red bone marrow equivalent plastics and 7LiF thermoluminescent dosimeters (TLD's) were used to determine the dose increase at various distances from the interface. Experimental results were compared with calculations using the Monte Carlo codes EGS (Electron Gamma Shower, SLAC) and CYLTRAN (Oak Ridge National Laboratory). The planar geometry was used as a benchmark geometry to compare the computer codes with experiment. After checking the accuracy of the codes for low energy electron transport, ACCEPT, a version of CYLTRAN, was used to investigate the radiation dose increase due to a point source of beta activity inside a polystyrene sphere bounded by aluminum. Spheres with radii of 200 and 500 microns were used. / Thesis / Master of Science (MS)