Dissertation (Ph.D.) - Simon Fraser University, 2005. / Dissertation (Dept. of Psychology) / Simon Fraser University. Includes bibliographical references (leaves 86-93).

Thesis (M.P.A. )--Kutztown University of Pennsylvania, 2006. / Source: Masters Abstracts International, Volume: 45-06, page: 2945. Typescript. Abstract precedes thesis as 2 leaves (iii-iv). Includes bibliographical references (leaves 52-56).

A dilemma is posed by studies of galaxy evolution at intermediate redshifts. If evolutionary effects are neglected, simple models predict number densities of faint galaxies which are 2—5x lower than observed at z ≅ 0.4. Yet the faint galaxy redshift distribution appears to be well modelled by the same no—evolution models. If low-mass starbursting galaxies are responsible for the excess, then the excess faint galaxy population should have rotation velocities lower than those of quiescent galaxies with the same luminosity. This thesis describes the results of a limited survey of the internal kinematics of intermediate redshift (z = 0.25—0.45) field galaxies. The goal of this survey was to find the unmistakable kinematical signature of low-mass starbursting galaxies. Using the Canada-France-Hawaii Telescope, spatially resolved spectra of the [O II] λλ 3726—3729 Å doublet emission line have been obtained for 22 galaxies. High-spatial resolution has made it possible to extract [special characters omitted] and [O II] disk scale length from each galaxy spectrum using synthetic galaxy rotation curve fitting. It is found that about 25% of the galaxies in the sample have [OIl] kinematics unrelated to rotation. [OIl] emission is concentrated in the nucleus in these “kinematically anomalous" galaxies. A Doppler ellipse similar to those found in local dwarf irregular galaxies has been observed in a z = 0.35 galaxy. An intermediate redshift Tully-Fisher (TF) relation defined by 12 kinematically normal galaxies shows that these galaxies have a systematically lower rotation velocity (i.e. mass) for their luminosity than expected from the local TF relation. These galaxies would have to fade by ~ 1.5-2 mag to lie on the local TF relation. This is consistent with starbursting dwarf galeixy models. Although the sample is small, there is also a hint that massive galaxies do not lie as far off the local TF relation as low-mass ones. However, as shown using a large sample of local galaxies, the scatter in the local TF relation is large, especially for late-type galaxies. Selection effects, particularly [OIl] emission strength, could be responsible for part of the observed TF shift if different star formation rates are responsible for the local TF scatter. A comparison with other works indicates that the luminosity-dependent luminosity evolution scenario neatly explains all the available internal kinematics and surface brightness data. / Graduate

New techniques are developed for relating the statistics of close galaxy pairs to the galaxy merger and accretion rates. Unlike the traditional pair fraction approach, these methods are shown to be robust to a number of selection effects related to the depth and completeness of the sample. These techniques are applied to the large, well-defined SSRS2 (z ∼ 0) and CNOC2 (0.1 ≤ ± ≤ 0.55) redshift surveys, yielding the first secure measurements of close pair statistics at low and moderate redshift. These results imply that the galaxy merger and accretion rates increase with redshift, approximately as (1 + z)2±1.5, for galaxies brighter than MB = –18. The CNOC2 survey is used to carry out a detailed comparison between close companions and field galaxies. Paired galaxies are found to be of slightly earlier spectral type, with a larger spread in properties. In particular, the spectral indices of close companions imply a more complex star formation history, as would be expected if galaxy interactions and mergers are prevalent. / Graduate

No description available.

This dissertation is the beginning of the development of a microscopic theory of the Knight shift. The Knight shift experiment has been used in superconductivity research throughout history, however, a complete understanding of the Knight shift in conventional as well as unconventional superconductors does not yet exist. Motivated by the results of a literature review, which discusses Knight shift anomalies in multiple superconducting materials, this research studies a new model of the Knight shift, which involves the processes involved in nuclear magnetic resonance measurements in metals. The result of this study is a microscopic model of nuclear magnetic resonance in metals. The spins of the spin-1/2 local nucleus and its surrounding orbital electrons interact with the arbitrary constant ${\bf B}_0$ and perpendicular time-oscillatory magnetic inductions ${\bf B}_1(t)$ and with each other via an anisotropic hyperfine interaction. An Anderson-like Hamiltonian describes the excitations of the relevant occupied local orbital electrons into the conduction bands, each described by an anisotropic effective mass with corresponding Landau orbits and an anisotropic spin ${\bf g}$ tensor. Local orbital electron correlation effects are included using the mean-field decoupling procedure of Lacroix. The metallic contributions to the Knight shift resonance frequency and linewidth shifts are evaluated to leading orders in the hyperfine and Anderson excitation interactions. While respectively proportional to $(B_1/B_0)^2$ and a constant for weak $B_0 > > B_1$, both shifts are shown to depend strongly upon ${\bf B}_0$ when a Landau level is near the Fermi energy.

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / The architecture of the High Rate (600 Mega-bits per second) Digital Demodulator (HRDD) ASIC capable of demodulating BPSK and QPSK modulated data is presented in this paper. The advantages of all-digital processing include increased flexibility and reliability with reduced reproduction costs. Conventional serial digital processing would require high processing rates necessitating a hardware implementation other than CMOS technology such as Gallium Arsenide (GaAs) which has high cost and power requirements. It is more desirable to use CMOS technology with its lower power requirements and higher gate density. However, digital demodulation of high data rates in CMOS requires parallel algorithms to process the sampled data at a rate lower than the data rate. The parallel processing algorithms described here were developed jointly by NASA’s Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL). The resulting all-digital receiver has the capability to demodulate BPSK, QPSK, OQPSK, and DQPSK at data rates in excess of 300 Mega-bits per second (Mbps) per channel. This paper will provide an overview of the parallel architecture and features of the HRDR ASIC. In addition, this paper will provide an overview of the implementation of the hardware architectures used to create flexibility over conventional high rate analog or hybrid receivers. This flexibility includes a wide range of data rates, modulation schemes, and operating environments. In conclusion it will be shown how this high rate digital demodulator can be used with an off-the-shelf A/D and a flexible analog front end, both of which are numerically computer controlled, to produce a very flexible, low cost high rate digital receiver.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / An algorithm for automatic modulation recognition of ASK, PSK and FSK was developed by Azzouz and Nandi. The algorithm has some serious problems at SNR of 10 dB and below. This paper describes a modification to the algorithm that significantly improves the performance for detection of ASK and FSK at moderate and low SNR.

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.

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.