A variable temperature dewar has been designed and built at the solid state laboratory of the University of British Columbia for infra-red absorption experiments at low temperatures. The dewar features a rotatable sample holder which brings any one of three samples into the light beam for comparison measurements. A removable tail section permits easy access to the samples. The dewar has been successfully operated over the 4°K to 50°K range. It can maintain sample temperatures to within 1°K for periods up to two hours. Approximately ten minutes is required to achieve any desired temperature in the operating range. The construction and calibration of a copper vs. constantan thermocouple is described. The thermocouple was used to measure the sample temperatures to an accuracy of about 1°K. Temperature variations of a few tenths of a degree could be detected. As a demonstration of the dewar's capabilities, an experiment was performed to measure the line width dependence of hole transitions from the ground state of the P3/2 band to the first excited state in the P1/2 band in boron doped silicon. The experiment showed that the line broadening starts at about 20°K and increases at higher temperatures. Several methods of improving the performance of the dewar are suggested. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Integrated optical devices use light to perform circuit functions. One class of devices using Ti indiffused waveguides in LiNb0₃ are investigated in this thesis. The applications studied include series and multibranch interferometers, a comparatorless A/D converter, and a high voltage sensor. An Impedance transformation equation for an exponential line is derived and used to obtain relations for the propagation constant of an optical waveguide with linearly graded index. The results are used to study the effect of a Ta₂O₅ film on the propagation constant of a Ti diffused waveguide. Heating in O₂ of the TA₂0₅ film, loading one arm of the Mach-Zehnder modulator, is shown to tune the modulator. The fabrication of devices in Y-cut LiNb0₃ by Ti diffusion is described. Microscope objectives are used to couple 0.6328 μm light into 4 μm wide waveguides through polished edges. An application of the Mach-Zehnder modulator and a two mode BOA (Bifurcation optique active) modulator to high voltage measurement is discussed. The output Intensity of the series interferometric filter is calculated. Measured results on a two section filter are presented. Also, the output intensity of a multibranch interferometric filter is determined. Experimental results on a three branch filter are included. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

No abstract available. Copyright / Dissertation (MMus)--University of Pretoria, 2008. / Music / unrestricted

Black and white photographs included. / Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1981 (Endodontics) / Bibliography : leaves 293-298. / Endodontic instruments are manufactured by many companies throughout the world.　Since no evidence exists in the literature concerning the variable quality of the instruments on the market, the following investigation was undertaken with the objective to compare a sample of instruments from some of the various companies. A total　of　1,680 files, reamers and hedstrom files representing seven different manufacturing companies were tested. Sizes 15, 30　and　50　were selected to represent the total size range of instruments.　The following physical　properties were measured: 1) Torsion; 2) Angular Deflection; 3) Stiffness; 4) Dimensional Standardization; 5) Preparation for Delivery; and　6) Corrosion Resistance. The data for each company was compared with the minimum Standard set by the ANSI　for the American Dental Association in Specification No. 28　for files and reamers and Specification No. 58　for headstrom files.　An analysis of variance and T-tests were also performed on the data to compare and contrast the instruments between companies. The results obtained showed that there was very little uniformity of standardization between manufacturers,　as well as within manufacturing companies.　The quality of the initial stainless steel　wire may determine the quality and strength of the final product of an endodontic instrument. It is difficult to determine whether one instrument is better than another.　Each instrument has different physical　properties than every other instrument.

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