At present several groups are analysing quasar absorption spectra to search for variation of the fine structure constant, alpha, across space and time. These studies compare the wavelengths of several transitions observed in the absorption clouds with those seen in the laboratory, and interpret anomalies as variation in alpha. One group has already presented evidence that alpha may have been smaller at an early epoch. Other groups using different telescopes see no variation. These studies use the ???many-multiplet??? method, which relies on the utilisation of many transitions in many ions to enhance the size of the effects and remove sources of systematic error. While this method offers an order-of-magnitude improvement in sensitivity over the previously used alkali-doublet method, the alpha-dependence (relativistic shift) of every transition used in the analysis must be calculated ab initio. In this thesis we present a method for the precise calculation of relativistic shifts, based on an energy calculation involving combination of the configuration interaction method and many-body perturbation theory. The many-multiplet method also introduces a potential systematic error: if the relative isotope abundances of the absorbers differ from terrestrial abundances then there can be spurious shifts in the measured wavelengths, which may be incorrectly interpreted as variation of alpha. A ???conspiracy??? of several isotopic abundances may provide an alternative explanation for the observed spectral anomalies. To account for these systematic errors we need accurate values of the isotope shift. We calculate these shifts using the finite-field method to reduce the problem to that of an energy calculation, which in turn is done using the same method used for the relativistic shift. We present the results of our calculations for a variety of atoms and ions seen in quasar absorption spectra. The results of this research should allow astrophysicists to measure isotope abundances in the absorbers directly. This can provide a test for models of nuclear reactions in stars and supernovae, and of the chemical evolution of the Universe. Our calculations can also be used in conjunction with measurements to extract changes in nuclear charge radii between isotopes.

Bibliography: leaves 242-268 / viii, 268 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Quantifies the effects of sleep deprivation on performance, validates methods of objectively measuring the sleep-wake activity of shiftworkers and investigates the effects of shiftwork on both sleep and performance in the laboratory and the field. Shows that actigraphy is a valid and reliable method of determining sleep-wake in shiftworkers. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1999

Bibliography: leaves 242-268 / viii, 268 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Quantifies the effects of sleep deprivation on performance, validates methods of objectively measuring the sleep-wake activity of shiftworkers and investigates the effects of shiftwork on both sleep and performance in the laboratory and the field. Shows that actigraphy is a valid and reliable method of determining sleep-wake in shiftworkers. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1999

Este trabalho teve como objetivo o desenvolvimento de um phantom de cabeça, com características acústicas e magnéticas equivalentes à do cérebro humano, para a formação de imagens, tanto por ultrasom quanto em ressonância magnética, para uso de treinamento clínico em neuronavegação. Geralmente, nos procedimentos de neurocirurgia, são usadas ambas as modalidades de imagens, sendo a ressonância comumente usada durante o processo préoperatório e, o ultrasom usado durante o procedimento cirúrgico, a fim de localizar a lesão e guiar o ato cirúrgico. Para tanto, o material que mimetiza o tecido cerebral foi desenvolvido a base de gelatina animal e vegetal. Pó de vidro e outras substâncias químicas foram adicionados à gelatina de modo que a atenuação acústica, espalhamento da onda e velocidade acústica ficassem equivalentes ao observado no tecido humano. Para mimetizar o sinal de ressonância magnética, material paramagnético foi adicionado à gelatina de modo que os valores dos tempos de relaxação transversal (T2) e longitudinal (T1) ficassem equivalentes aos observados nos tecidos do cérebro humano. Testes de neuronavegação foram realizados com um sistema desenvolvido no próprio laboratório. Para simular um processo cirúrgico, uma janela de acesso ao tecido cerebral foi criada no lado esquerdo da cabeça. As propriedades acústicas e magnéticas do tecido mimetizador proporcionaram contraste nas imagens de ultrasom e ressonância magnética equivalentes aos observados no tecido do cérebro humano. A morfologia e o tamanho do phantom são equivalentes ao de um cérebro de uma criança de aproximadamente cinco anos. Para avaliar o potencial do phantom como uma ferramenta para treinamento de um processo précirúrgico, foi realizada o préprocessamento e reconstrução 3D do phantom a partir das imagens de ressonância magnética, utilizando um software comercial Brainvoyeger® . / The goal of this work was to make a head phantom that can be used either in Ultrasonography (US) or Magnetic Resonance Imaging (MRI) to be applied as guided training for head surgery in a neuronavigation system. Generally, for neurosurgery procedures, both images modality (US and MRI) are used as guide. MRI images are used for previous evaluation of surgery, for localization of the tumor, choice of window on the head for craniotomy and path into the brain to access the tumor. The ultrasonography of the brain is used during the surgery procedure to guide and control the removal of the tumor. The phantom was developed with mimickingtissue material to generate contrast and intensity in the MRI and US image equivalent to that one obtained in human brain. The base material was made of pork gelatin (Bloom 250). The acoustic properties of this material (velocity, attenuation and Speckle) were controlled adding formaldehyde and glass bids. The magnetic properties (T1 and T2 relaxation) were controlled by adding sodiumEDTA and cupric chloride (CuCl2). The morphology and size of the brain were modeled into a head shell of rubber with size and geometry equivalent to a head of a child of approximately 5 years old. The evaluation of the phantom as tools for neuronavigation training was done simulating a surgery procedure. First, a volume of MRI image of the phantom was acquired using a tomography of 1.5 T (Siemens Vision®). After, using a 3D special sensor coupled to micro convex ultrasound transducer, the ultrasound and MRI image, of a same region, was showed simultaneously using a navigator software developed in the own lab by another student. For this evaluation, a craniotomy was done in the right side of the phantom. The 3D reconstruction of the phantom from MRI images volume was evaluated using commercial software Brainvoyeger®. The size, morphology of the head and the US and MRI image quality 12 of the simulated brain were very close to those ones observed in the brain of a young person. This product is very useful as a tool for training neurosurgeons and for calibration of neuronavegator system.

Shiftwork is common in the private sector but not exclusive from the public sector like nursing. In order to secure a continuous operation, and optimization of equipment, businesses introduced shiftwork. The author wanted to test certain hypotheses to better understand the impact of shiftwork. In this research the author first embarked on a theoretical study into shiftwork and its associated problems, which include the impact on productivity, the impact on the employer’s attitude towards the work, the impact on the family life, the impact on social life, the impact on physical health and the psychological effects. Thereafter, an empirical study was conducted to ascertain to what extend shiftwork affects productivity and the life of the employees. The data was then analysed to explain the impact of shiftwork and productivity. Lastly, recommendations were made based on the research.

No description available.

This thesis presents a study of the applications of the variational principle to periodic lattices. A calculation of the conduction Knight Shift in the Alkali Meals is chosen as an example of the calculations possible with this method. The Knight Shift is discussed with reference to the contributions of both the core and conduction electrons. The approximation of neglect of the effect of the core electrons as found in previous calculations is discussed and its validity questioned. / Thesis / Master of Science (MS)

In phase shift interferometry (PSI), several factors affect measurement accuracy, such as piezoelectric transducer (PZT) calibration (i.e. PZT slope error) and PZT nonlinearity, vibration, spurious reflection, source bandwidth, detector nonlinearity, and detector noise. The effects of these error sources on several algorithms to solve the phase of the wavefront are studied. When the simple arctangent formula is used, if the PZT slope is properly adjusted, the error due to the PZT quadratic nonlinearity can be tremendously reduced. An exact solution is derived to remove the error when the PZT quadratic nonlinearity is large. Although Carre's formula is insensitive to PZT slope, this formula is more sensitive to the detector nonlinearity than the simple arctangent formula. For most error sources, the error of the phase solved has a double-frequency characteristic. Thus, averaging two measured phases of two runs, which have a ninety degree phase shift related to each other, can effectively reduce the error. For a small vibration, the phase error has a very simple relation to the vibration amplitude, and a very complex relation to the vibration frequency. Although the error caused by vibration has this double-frequency characteristic, the averaging technique does not apply. The error caused by spurious reflection does not have such a characteristic. A new algorithm is proposed to eliminate the phase error caused by certain types of spurious reflection. When detector noise is concerned, the phase error is inversely proportional to the modulation of the intensity times the square root of the number of steps/buckets. For the shot noise, the phase error is inversely proportional to the fringe contrast times the square root of the total number of photons. In practice, the shot noise is very much smaller than the detector noise. In a practical environment, PZT calibration, vibration, and spurious reflection have much more prominent effects on the PSI than the source bandwidth, detector nonlinearity, and detector noise. When spurious reflection and vibration are under control, and the signal-to-noise ratio is about 20, the PSI has an accuracy of 2 degrees, i.e. 3.3nm at 633nm. Because vibration and detector noise are random error sources, the errors caused by them can be reduced by averaging many measurements. However, the error caused by the other discussed sources cannot be reduced by averaging many measurements.

A Simultaneous Photometer for Infrared and Visual light (hereafter SPIV) has been constructed. SPIV uses three dichroic filters to divide light from a common aperture in the telescope focal plane into four colors with bandpasses (in microns) of: 0.42 to 0.7 (V(B)); 0.7 to 0.95 (I(B)); 1.45 to 1.8 (H); 1.97 to 2.27 (K). The H and K bands are detected by liquid helium cooled InSb diodes. I(B) is detected by a helium cooled Si diode, and V(B) by an uncooled EMI 9658R photomultiplier tube. The instrument response function (IRF) including the effect of atmospheric transmission is shown. The maximum usable aperture size of 2 mm corresponds to 7 arcseconds on the Multiple Mirror Telescope and to 20 arcseconds on the UAO 61" and 90" telescopes. Information about the sky brightness is combined with the IRF to calculate the expected background noise. These calculations show SPIV should be background noise limited in all bands. Observations show this is true except for I(B), which is detector noise limited. The optical alignment of the four channels is shown to be satisfactory. The SPIV instrumental magnitude system is defined. Observations of 40 radio galaxies and 39 non-radio first ranked cluster galaxies with known redshifts ranging from 0.019 to 1.6 are reduced on this system, correcting for atmospheric extinction, reddening, and aperture. The transformation to standard magnitude systems is derived. The reduced V(B)-H, I(B)-H and H-K colors as a function of redshift are compared for the radio and non-radio galaxies using statistical tests. No convincing differences are found, with the possible exception of H-K in the z = 0.2 to 0.4 range. These colors are also compared to a "no evolution" prediction generated by redshifting a composite spectrum of nearby elliptical galaxies, and to evolutionary models from Bruzual (1981). Passively evolving models with little residual star formation and a galaxy formation epoch z(f) > 3 are slightly favored by H-K observations. These models predict about one magnitude brightening at H by a redshift of one. The I(B)-H color becomes redder with redshift much faster than the reddest model, and shows large scatter for z 3. Residual star formation models require an older universe than is allowed by qₒ = 0.5, Hₒ = 80 km/sec/Mpc to fit the red V(B)-H envelope at high redshift. Some galaxies show strong blueward deviations for z > 0.4. This behavior is most easily explained by episodes of star formation involving small fractions of the total number of stars. Because of the flatness of H-K and I(B)-H at high redshift, and the scatter in V(B)-H, determining redshifts > 0.4 from broadband colors will be difficult.

No description available.