VictorJuiz/thesis huggingface dataset:
The Magnetometric Off-Shore Electrical Sounding (MOSES) Method and Its Application in a Survey of Upper Jervis Inlet, British Columbia

Magnetometric off-shore electrical sounding, acronym MOSES, is an adaptable sea floor electrical exploration method. It circumvents the shortcomings of traditional exploration methods, such as dipole arrays and magnetotelluric soundings, which are adversely affected by the high conductivity of sea water. In this thesis, I describe the development of the MOSES theory, the equipment and methodology, and the processing and interpretation of data from a successful test survey. The method employs a vertical bipolar wire source. Current is injected through a sea floor source electrode and returns to a sea surface sink electrode. The current penetrating the sea bed generates a sea floor azimuthal magnetic field which is proportional to the contra.st between sea and crustal resistivities. Transverse isotropy does not affect the inherent axial symmetry of the method. I derive the magnetic field equations in wavenumber domain for a. transversely isotropic layered earth. The solutions for a halfspace with and without a thin intermediate layer show that intermediate conductive and resistive layers can be resolved. Current channelling is affected more by the host medium anisotropy than by the layer anisotropy. I derive apparent resistivity and anisotropy formulae which aid interpretation. The sea floor receiver is a remote encapsulated microprocessor controlled magnetometer which is deployed at the start of a survey and recovered at the end. My algorithm triggers the preset periodic data acquisition and stacking cycles, and the data retrieval. The transmitter is driven by a ship-board 2 kilowatt square-wave current transvertor which is synchronized with the receiver clock. I show that the source-receiver geometry must be known for proper data interpretation. Survey lines were placed in Princess Royal and Queen's Reaches of Jervis Inlet. I process the stacked station data to yield only the transmitted signal harmonics, and interpret the data using one- and two-dimensional and angled wire source models. The sediment resistivities are about 2 ohm-metres; the apparent porosities agree with core samples. The Princess Royal Reach sediment thickness and basement resistivity are not resolved. The Queen's Reach sediments a.re about 600 metres thick. The basement is very resistive; thus if basement hydrothermal flow is causing observed high heat flow in upper Jervis Inlet, it is localized.

Keywords: Geophysics
Advisor: Edwards, R. Nigel
The Development and Evaluation of a Crosshole Seismic System for Crystalline Rock Environments

Crosshole seismic techniques appear to be useful in the evaluation of the mechanical properties of inhomogeneous crystalline rock masses, particularly when near surface weathered zones prohibit the use of high resolution surface seismic methods. A project has been undertaken to develop a crosshole seismic system specifically designed to meet the criteria of the Canadian Nuclear Fuel waste Management Program. Because the rock masses to be studied are at depth, the system was required to operate in environments with high hydrostatic pressures of up to 15 mPa, and was required to be non-destructive, because of the high cost of the boreholes. The system that has been built utilizes piezoelectric ceramics in a wall-clamped accelerometer geometry as both receiving and transmitting transducers. Although the peak power of the transmitter is limited by the design criteria, the highly controllable nature of the piezoelectric ceramic allows the use of a continuous transmitted signal. The impulse response of the rock mass is then estimated using cross-correlation techniques. In this manner significant noise reduction is obtained and the detection of low level signals is enhanced. The received signals are digitized and processed in the field using a microcomputer system. Tests have been conducted which demonstrate that crosshole seismology is capable of evaluating the mechanical properties of rock masses. P-wave transmissions on paths of up to 300 m and S-wave transmissions on paths of up to so m nave been recorded, and show that both velocity and amplitude information in the data reflect geological and geophysical effects observed using other methods. The system has also been used to study tube wave phenomena, which can provide information on the shear modulus of the rock in the absence of direct shear arrivals. Although problems exist in accurately determining the position of the probes and in calibrating the amplitude response of the system, valuable information can be collected and interpreted with the present system. Future developments in instrument design and in methods of tomographic reconstruction hold great promise in several fields of application, including mining engineering and rock mass assessment.

Keywords: Geophysics
Advisor: West, G. F.
The calculation of electromagnetic fields in a horizontally layered earth for an arbitrary source

In order to explore sedimentary environments with electromagnetics techniques, a greater understanding of the benefits and problems with the available methods must be obtained. In this thesis, an efficient method of calculating the response of a horizontally layered earth to an electric or magnetic dipole source has been developed. The computational effort involved in calculating response of a large grounded or ungrounded source was significantly reduced by using the concept of lagged convolution, and a novel integration technique. The integration technique permits the evaluation of the fields due to any arbitrary source on the surface of a layered earth. The combination of the two techniques will hopefully reverse the present thinking that it is much too expensive to do routine interpretation of large source responses using generalized inversion schemes. Since many rocks exhibit anisotropy and induced polarization, both effects are described in terms of the fields of a grounded electric bipole on the surface of a layered earth. Furthermore, the concept of considering a grounded source as two individual sources is used to explain the field responses to half-space and layered earth models. In general, the galvanic part of the source is sensitive to anisotropy and IP, while the inductive part of the source is not. The major advantage of a bipole source is that the fields due to subtle changes in conductivity can be discriminated. This makes a grounded bipole source suitable for EM exploration of sedimentary environments where various conductivity contrasts may exist between different layers in a stratigraphic section.

Keywords: Geophysics
Advisor: West, G. F.
On the electromagnetic response of non-uniform overburden layers: scale model experiments

The first problem the interpreter of electromagnetic data in mineral exploration is required to solve is to differentiate between anomalies caused by metallic conductors in the bedrock and those caused by any other feature. Many subsurface conductors other than ore deposits are conductive enough to cause electromagnetic anomalies. One of the main sources of such "geological noise" is the overburden layer or inhomogeneities in it. In this thesis the electromagnetic response of these inhomogeneities are investigated by means of scale model experiments with the horizontal loop technique of geophysical prospecting, Several characteristics of the response that will help to distinguish the electromagnetic response of a non-uniform overburden layer, from that caused by a bedrock-mineralized conductor are reported. To recognize these characteristics, survey data at several frequencies or coil separations are required.

Keywords: Geophysics
Advisor: West, G. F.
Interpretation of Airborne EM (Electromagnetic) Measurements Based on Thin Sheet Models

An airborne electromagnetic (AEM) prospecting system is used as a very rapid means of economically searching large geologically potential areas for sulphide ore bodies within the top few hundred feet of the earth's surface. This is possible because massive sulphide ores are usually much more electrically conductive than most host rocks. The system usually consists of a transmitting coil and a receiving coil flown by an aircraft. The transmitting coil generates a time-varying magnetic field in the low audio-frequency range (100-4000 hz). Any small perturbations of a component of the field are then recorded continuously as the aircraft flies along flight lines. The record over a conducting body is called an anomaly profile. The magnitude of an anomaly depends on conductivity3 size and shape of the conducting body causing it3 and the flight direction and height of the AEM system. Interpretation is based on a qualitative or quantitative comparison of the observed response (anomaly) with the responses that would be observed by the system over simple idealized conductors. Many geological conductors are somewhat sheet-like in form and dip into the earth at an appreciable angle. The extent of the sheet is often large compared to the region sensed by the system. Both for airborne and ground EM measurements the single most important model has been the (thin) half-plane. For the multitude of AEM systems actually in use even this simple model has not been fully explored. The only available data are the peak amplitudes of the vertical half-plane for 'small-scale' systems (inaccurate) and the Lockwood quadrature system, and some profiles over perfectly conducting half-planes for a variety of systems plus a few random model profiles for a few systems. The thesis contains systematic studies with several AEM systems over vertical and dipping half-planes, vertical and flat ribbons, strike limited sheets, vertical half-plane under a thin flat overburden and two parallel half-planes. Studies have been restricted to thin conductors because of modelling convenience, and to keep the number of parameters under control. While thick bodies are interesting, the simpler thin case must obviously be done first. Field and model data have been compared in a number of cases and it is found that most of the field data is explicable without further elaboration of the models. However, certain discrepancies are found even in these selected cases which indicate that additional features of the conductors may have to be taken into account (and cast suspicion on the quality of altimetry). In the cases examined, it did not seem that the conductivity of host rocks was having much influence. The study indicates that it is often possible to discriminate flat-lying conductors from dipping conductors with the present systems. Other effects such as finite extent, influence of overburden, and fringe conductors are difficult to identify from a single flight with a current AEM system.

Keywords: Geophysics
Advisor: West, G. F.
A 131-Year High-Resolution Record of Coccolith Assemblages in Laminated Sediments from the Arabian Sea

This study looked at a 131-year high-resolution record of coccolith assemblages in laminated sediments from the Arabian Sea. The SO90-39KG core obtained from the northeastern Arabian Sea was sampled at an annual resolution for the period of 1861-1993 A.D. Analyses of Scanning Electron Microscope (SEM) images of these samples revealed a declining trend in the relative abundances of the upper to mid photic zones coccolithophore species and an increasing trend in the relative abundances of the lower photic zone coccolithophore species over the 20th century. These trends could be the result of a reduction in paleoproductivity caused by the deepening of the nutricline and the thermocline due to a warming climate. The 1883 A.D. Krakatau eruption was also evident in the results as decreased paleoproductivity. Similarities between the observed trends and monsoon precipitation as well as sunspot cycle records were also observed. No particular similarity with El-Nino Southern Oscillation (ENSO) record could be detected. Caution should be observed regarding the correlation of the results obtained here to past climatic and geologic events.

Advisor: Bollmann, Jorg
Characterization of the role of domains and subdomains of aggrecan in post-translational processing and secretion

Aggrecan is the major proteoglycan in the articular cartilage. This molecule is crucial to the chondroskeletal morphogenesis during development and it is also important in the proper functioning of articular cartilage by providing hydrated gel structures (via its interaction with hyaluronic acid and link protein) which endow the cartilage with load bearing properties. Aggrecan is a multimodular molecule expressed by chondrocytes. To determine the role of each aggrecan domain in its post-translational modification and secretion, we generated a number of recombinant DNA constructs bearing various aggrecan domains individually or in combinations with other domains. We observed that G1 and G2 domains inhibited product secretion and GAG chain attachment whereas, G3 domain promoted secretion and GAG chain attachment. Knowing that G1 and G2 inhibited secretion, we set to identify which region of G1 and G2 shared the inhibition of secretion properties. Utilizing recombinant genes, we demonstrated that the first tandem repeats of G1 and G2 inhibited product secretion if expressed alone or in combinations with other domains and subdomains. We next tried to isolate the amino acid residues in the first tandem repeat of G1 involved in the inhibition of secretion by mutagenesis experiments. C-terminal mutagenesis of the first tandem repeat of G1 did not promote the secretion, however, N-terminal mutagenesis (point mutations and deletions) gave rise to enhancement of secretion. We noticed that there were four N terminal residues, FHYR, which seemed to be important in inhibition of secretion, however, we next realized that these four residues were part of a stretch of 55 amino acids required for the inhibitory property. Yeast two-hybrid analyses also indicated that TR1 of G1 is interacting with ER-bound chaperones.

Keywords: molecular biology
anatomy & physiology
animals
biological sciences
proteoglycan
articular cartilage
aggrecan
secretion
The Meaning of Alienation and the Struggle to Learn to Relate

Alienation, a pervasive contemporary problem, has been studied for many years by scholars who represent numerous and diverse disciplines. The issue has been associated with a plethora of sociological and psychological ills. But "alienation" as a concept has not been defined clearly. Separation of some sort seems to be the only theme that binds the various usages of alienation into a single concept. Few studies of the topic have been attempted in psychology and research into interpersonal alienation hardly exists. The main intent of this dissertation has been to clarify the meaning of peoples' struggle to learn to relate. A process of understanding had to be developed to elucidate the meaning of this particular form of separateness. Mainstream psychological research stresses the differentiation between subject and object, but this kind of split, within and between people, is frequently used in the literature to define alienation. A method could not be employed that took only a traditional object stance. Relational understanding needed to be added to empirical knowledge. Thus a second goal of this study has been to further the development of intersubjective research. As an ideal model, Martin Buber's conception of an alternating dialectic between I-It and I-Thou modalities of knowing was employed. To satisfy the empirical goal, a system of interpretation was used. From this process of understanding, eighteen inter-related variables emerged. These aspects of the experience were common to each participant in the study. These variables were further clarified through reflecting on the philosophical anthropology of Martin Buber and the psychosynthetic model of Roberto Assagioli. The dissertation ends with a discussion of some implications for: an understanding of interpersonal alienation and the struggle to learn to relate, intersubjective research, work with alienated people, and education.

Keywords: Education
alienation
relationship
Buber
Assagioli
Psychology
Advisor: Weiser, John
Analysis and processing of dark-field electron micrographs for three-dimensional reconstruction

Dark-field electron microscopy has the potential of providing high resolution images of biological molecules with a resolution of 5 A. The two dimensional information from dark-field electron micorgraphs may be used to generate a three dimensional structure of the molecule if the relative projection directions of the images are known. This thesis describes computational techniques aimed at recovering this three dimensional information from single images of molecules which adopt unknown orientations with respect to the imaging beam. Dark-field images contain large amounts of noise, primarily a result of structure in the carbon film used to support the specimen. The application of maximum entropy methods, in an attempt to enhance the quality of the original images by removing the noise, is described. It is seen that, to be useful, these methods require a number of other constraints. However, the additional constraints lead to significantly increased computational times which render the algorithm impractical. An algorithm is described that permits the a posteriori determination of the relative projection direction of a large number of molecules. The method uses the central section theorem to determine the relative orientations of the images. Quaternion mathematics is used to determine optimum alignments of images. A number of algorithm-specific parameters are developed to indicate the degree of success of the alignment procedure. Simulated images and dark-field electron micrographs of the Klenow Fragment of DNA Polymerase I are used to test the efficacy of the alignment algorithm. The simulations indicate, on the basis of signal-to-ratio as a measure of image quality, that the algorithm should be able to determine projection directions from dark-field micrographs of single molecules. However, application to electron micrographs provides low quality alignments. Reasons for the discrepancy between the simulations of experimental situations are discussed. Preliminary experiments indicate that visual selection of high quality images yields improved alignments. It is suggested that this improvement results from selection of particles that have retained their integrity during the imaging procedure. It is concluded that the alignment procedure will probably be successful when applied to higher quality dark-field electron micrographs.

Keywords: Biophysics
Biological sciences
Neuroimaging evidence for the representation of salience in the neural correlates of attention and awareness in the human brain

Sensory stimuli must be at the focus of attention to reach conscious awareness. Attention may serve as a mechanism for identifying salient (i.e., potentially behaviourally relevant) features of the sensory environment. Neuroimaging studies have identified a frontal-parietal-cingulate network of regions involved in attentional control and conscious sensation. The present work was designed to test the hypothesis that these regions represent the salience of sensory stimuli. Brain regions sensitive to stimulus salience across multiple sensory modalities were identified in four studies using event-related functional magnetic resonance imaging. A right-lateralized network of frontal, parietal, cingulate, and insular cortical areas responded to salient changes in visual, auditory, and tactile stimuli. These areas also showed sensitivity to both top-down and bottom-up factors affecting stimulus salience. They responded more strongly to changes in visual or auditory stimuli when the stimuli were task-relevant rather than task-irrelevant. In the absence of a task, these areas responded more strongly to novel than familiar visual, auditory, and tactile stimuli. These areas also showed prolonged responses to stimuli with prolonged salience. They responded tonically throughout the duration of a prolonged painful stimulus but only transiently to the onset and offset of a prolonged non-painful stimulus. Consistently salience-sensitive regions included the temporoparietal junction, inferior frontal gyrus, anterior insula, anterior cingulate cortex/cingulate motor area/supplementary motor area, and thalamus. These findings suggest a functional role for the frontal-parietal-cingulate networks involved in attentional control and awareness. These areas may serve as arbiters of salience, identifying currently important features of the sensory environment within the current behavioural context of the organism. The importance of these areas for subjective conscious experience may stem from their role in representing features of the external sensory environment in terms of how they relate to the intrinsically subjective needs of the organism, within the context of its current behaviour, motivations, and homeostatic requirements.

Keywords: Biological sciences
Neuroimaging
Attention
Awareness
Brain
Neurology
Advisor: Davis, Karen
Cathode interface structure in organic semiconductor devices

As organic semiconductor technology matures, enhancement requires understanding/engineering of the cathode/organic interface. In this work, using X-ray photoelectron spectroscopy (XPS) and common materials for organic light emitting diodes (OLEDs), the expected interfacial structure in conventionally fabricated devices has been described and some simple predictive methods developed. The buried electrode/active layer interface was examined by analysing: (1) both sides of the interface in conventionally fabricated devices under high vacuum with the unique peel-off technique, and (2) monolayers of one material grown atop another. Connections were drawn between the interfacial structures in devices, those observed during traditional surface science investigations, and the device behaviour. A critical insight is that no one metal or metal/interlayer combination may be used as a universal cathode. Rather, certain criteria for interfacial structure and stability must be confirmed to ensure adequate performance. This can be determined through simple material property information, such as lattice constants, or with inorganic analogues for organic molecules. For combinations of metals and 8-tris(hydroxyquinoline aluminum) (Alq 3 ), interfacial reactions can be predicted by assuming Al2 O 3 as an inorganic analogue. Using this analogue, molecular fragmentation may be described as a simple metal-exchange oxidation-reduction reaction. As cathode complexity increases, such simple descriptions lose validity. This work shows that all three components (organic/LiF/metal) are required to adequately describe the interfacial structure of bi-layer cathodes. The major conclusions regarding the role of LiF are: (1) that 5-10Å LiF changes the cathode oxidation behaviour, predicted by the lattice mismatch of the interlayer with the metal. Oxidation is suppressed for Al, which is well matched to LiF; for Mg, which has poor matching, preferential formation of carbonates occurs. Device behaviour is related to the metal oxidation, such that Al/LiF cathodes are superior to Mg/LiF ones. (2) that near the interface, LiF forms charge transfer complexes with electron transporting molecules. (3) that the cathode should be considered a metal-insulator-metal capacitor with the organic layer acting as the bottom electrode. The usable thickness of LiF is dependent on the conductivity of the layer. These insights indicate some of the conditions necessary for adequate device performance and longevity, useful for future device optimization.

Keywords: Materials Science
Advisor: Lu, Zhenghong