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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

STRUCTURAL GEOLOGY AND HYDROCARBON PRODUCTION

Patterson, Amy Atamanczuk 22 March 2011 (has links)
The location and orientation of tectonic structures and the size and distribution of karst-related disturbances in the Barnett must be known in order to maximize production of natural gas from the reservoir. Knowledge of these features has already been utilized in developing the Barnett Shale, both in selecting well sites and in choosing the direction to drill horizontal wells. In this study, I identify and map the faults and fractures in northwestern Johnson County, establish their relative ages, and determine their origins. Also, I relate well productivity to the detailed structural setting with the goal of establishing guidelines for selecting well sites and orienting horizontals.
22

A METHOD FOR EVALUATING THE EFFECTS OF STRESSES AND ROCK STRENGTH ON FLUID FLOW ALONG THE SURFACES OF MECHANICAL DISCONTINUITIES IN LOW PERMEABILITY ROCKS

Enderlin, Milton Bock 22 March 2011 (has links)
Changing stress can affect the ability of fluid to flow along mechanical discontinuities such as faults, fractures, or bedding planes. Stress can cause mechanical discontinuity to reactivate in shear, resulting in an increase in fluid flow. The values for present-day horizontal stress orientation and magnitude can be constrained from structural geology principles via interpretation of mapped active features and wellbore information such as drilling history and image logs. Stress magnitudes and orientation information is used to calculate the shear and normal stress magnitudes acting on the mechanical discontinuities of all possible orientations. Furthermore, the necessary magnitudes of fluid pressure within each mechanical discontinuity that would be required to encourage shear failure reactivation are evaluated. A laboratory experiment and an example from the Barnett Shale play are presented as an application of the method. The Barnett example identifies likely orientations of pre-existing fractures that could interact with fluids during hydraulic fracture stimulation.
23

LARYNGEAL AGING AND THE ACOUSTIC AND TEMPORAL CHANGES OF ULTRASONIC VOCALIZATIONS IN AGED RATS

Peterson, Jennifer R. 23 March 2011 (has links)
Human voice quality changes with senescence. There are corresponding age-related changes in laryngeal morphology. We investigated acoustic features of USVs in Long Evans male rats (Rattus norvegicus), young (5 months), middle-aged (18 months) and aged (26 months). Young rats produced more calls, followed by aged, and middle-aged. Cross-sectional analysis of all calls revealed that USVs of young rats were higher in mean peak frequency, amplitude, and max frequency, compared to middle-aged but they did not differ significantly from aged. Young rats produced more higher frequency calls, but the middle-aged and aged produced more lower frequency USVs and audible calls. These data suggest that age-related changes in USVs occur before 18 months. Histology revealed positive correlations between elastin and maximum frequency of USVs, while hyaluronic acid was positively correlated with peak frequency and maximum frequency. This data indicate that USVs may degrade due to micro-structural changes to aging vocal fold tissue.
24

STUDIES OF SURFACE STATES IN ZINC OXIDE NANOPOWDERS

Peters, Raul M. 28 March 2011 (has links)
The surface of ZnO semiconductor nanosystems is a key performance-defining factor in numerous applications. In this work we present experimental results for the surface defect-related properties of ZnO nanoscale systems. Surface photovoltage spectroscopy was used to determine the defect level energies within the band gap, the conduction vs. valence band nature of the defect-related transitions, and to probe key dynamic parameters of the surface on a number of commercially available ZnO nanopowders. In our experimental setup, surface photovoltage characterization is conducted in high vacuum in tandem with in situ oxygen remote plasma treatments. Surface photovoltage investigations of the as-received and plasma-processed samples revealed a number of common spectral features related to surface states. Furthermore, we observed significant plasma-induced changes in the surface defect properties. Ex situ positron annihilation and photoluminescence measurements were performed on the studied samples and correlated with surface photovoltage results. The average positron lifetimes were found to be substantially longer than in a bulk single crystalline sample, which is consistent with the model of grains with defect-rich surface and subsurface layers. Compression of the powders into pellets yielded reduction of the average positron lifetimes. Surface photovoltage, positron annihilation, and photoluminescence spectra consistently showed sample-to-sample differences due to the variation in the overall quality of the nanopowders, which partially obscures observation of the scaling effects. However, the results demonstrated that our approach is efficient in detecting specific surface states in nanoscale ZnO specimens and in elucidating their nature.
25

DEVELOPMENT OF AN ADULT ATTACHMENT SCALE: PRELIMINARY STUDY

McKenzie, Lewis Brooks 28 March 2011 (has links)
This is a preliminary study of a new and unnamed attachment scale. The scale consists of 160 Likert-type items on a 4 point scale. Item generation was based upon the states of mind scales contained within the Adult Attachment Inventory (AAI) and upon the authors own clinical experience. Item response modeling was used to generate item parameter estimates for items in each of the three main attachment classifications: avoidant, secure, and entangled. Parameter estimates were based upon the responses of 484 participants. Additionally, parameter estimates for 9 categories that may be indicative of an unresolved classification were established from the responses of 792 participants. Initial sample distributions of attachment classification closely reflect the established population distributions for the AAI. As the AAI is currently the only validated measure of adult attachment, and its use can incur a cost of $500 per participant, this unnamed scale may prove to be a low-cost alternative to the assessment of adult attachment. This scale may facilitate the research of adult attachment and allow for screening in real-world situations (e.g., adoption) where the cost of the AAI prohibits its use.
26

DEPOSITIONAL SYSTEMS IN THE ATOKA AND MORROW SERIES (PENNSYLVANIAN), HALEY FIELD AREA, LOVING COUNTY, TEXAS

Hasler, William Everett 02 April 2009 (has links)
Haley Field, Loving County, Texas has produced over 300 bcf of gas from Morrowan and Atokan strata in the Delaware Basin. However, only one in four wells drilled in the field is economic. These reservoirs were deposited in a deep-water setting in a basin undergoing active tectonism in response to the Marathon-Ouachita orogeny. The Central Basin Uplift, the Grisham Anticline, and the Red Hills Arch all altered sediment distribution in the basin. Lower and middle Morrow strata are multiple-source submarine ramp turbidites that flowed from the Northwest Shelf and the Central Basin Uplift. A carbonate shelf edge developed along the Northwest Shelf during the late Morrowan and prograded basinward during the Atokan. Channels cut into the high-relief shelf edge fed sand-rich turbidites deposited on the basin plain. Exploration potential exists in stacked channels, fan lobes and overbank deposits associated with turbidites both in the Morrow and the Atoka.
27

Appropriate Design Elements and Native Plant Selection for Living Roofs in North Central Texas

Kinder, Jonathan William 03 April 2009 (has links)
<bold>Living roofs</bold>, or green roofs, provide ecosystem function to rooftops. Plant selection for living roofs in North America has been dominated by members of the <italic>Sedum</italic> genus and other rocky ecosystem plants. This paper investigates the <bold>Walnut Limestone barrens and glades</bold> communities as an appropriate ecosystem from which to choose plant species for use on living roofs in <bold>north central Texas</bold>. This study presents plant performance data from six months of monitoring five test module treatments and two field sites. Performance data suggests the Walnut barrens and glades are viable ecosystems to use as a template for plant selection. First growing season results indicate <bold>commercial growth medium substrate provides stability</bold> and predictability, while a <bold>native soil substrate provides resilience</bold> and an active <bold>seedbank</bold> for annual germination. Four species were identified as viable living roof candidates for north central Texas: <italic>Buchloe dactyloides, Muhlenbergia reverchonii, Opuntia phaeacantha</italic> var. <italic>major</italic>, and <italic>Yucca pallida</italic>.
28

FABRICATION AND OPTICAL PROPERTIES OF ERBIUM-DOPED GROUP IV NANOWIRES AND THEIR CORRESPONDING OXIDES

Wu, Ji 04 April 2007 (has links)
As photolithography-based top-down methods are approaching their fundamental limits, new conceptual methods are emerging as possible alternatives to replace them. Alternatives based on bottom-up approach rely on the assembly of basic building blocks such as nanowires. One-dimensional Group IV semiconductors (Ge, SiGe) are very important electronic materials. However, they cannot be used in optoelectronics due to their intrinsic indirect band gap properties. One of the most effective approaches to make them luminescent is the introduction of impurities such as Er3+ ions. Er3+ is of technologically important because its emission lies at the transmission window of silica. Another focus of our research is to fabricate one-dimensional Er-doped Group IV oxide amplifiers. Ideally, these NWs could be used as building blocks in the field of near-IR nanophotonics. The basic building block Ge NWs were first fabricated via a vapor-liquid-solid synthetic route. Next, these Ge NWs were doped with Er3+ ions. These NWs were characterized using electron microscopy and spectroscopy, showing that these nanowires possess a core-shell structure. Activation and possible underlying mechanism for the Er-related emission have also been explored. Since Ge NWs are readily oxidized, Si was introduced to form stable SiGe alloys in order to circumvent this problem. Three different alloyed architectures were prepared. A combination of electron microscopes in concert with both elemental and Raman microanalyses were used to investigate the composition and structure of these Er-doped SiGe NWs. The Er coordination environment and Er-related luminescence properties have also been investigated. Er-doped group IV oxide nanofibers were fabricated via an electrospinning approach. These nanofibers were then characterized using X-ray diffraction, electron microscopy, and spectroscopy to investigate their structures and compositions. The Er3+ ions in Er-doped GeO2 nanofibers were found to be excited through a GeOx-mediated process. Lastly, the Er sensitizer, GeOx was introduced deliberately into Er-doped SnO2 nanofibers. These composite nanofiber structures were characterized using electron microscopy and spectroscopy, showing that SnO2 can be reduced by Ge to form Sn metal. A longer Ge deposition time leads to the formation of Ge nanorods. The Er-related luminescence from these sensitized nanofibers has been enhanced by almost 2 orders of magnitude.
29

The impact of counselor burnout on therapeutic relationships: a multilevel analytic approach

Garner, Bryan 11 April 2006 (has links)
Research has long recognized the importance of the client-counselor therapeutic relationship in providing effective treatment. However, only limited research to date has examined the factors that are involved in its development, especially the impact of counselor factors. Likewise, research has long assumed that burnout has a detrimental impact on service relationships, however this fundamental assumption has remained virtually untested since the concept of burnout was first introduced 30 years ago. In an attempt to address both of these gaps in the literature, the current study used a multilevel modeling technique to examine the impact of counselor factors, including burnout, on the client-rated therapeutic relationship. Data for the current study came from two corrections-based therapeutic communities and included 734 clients nested within 44 counselors. Findings suggest that although limited, counselor factors do indeed impact the therapeutic relationships as rated by the client. In the current study, significantly higher counselor rapport ratings were given to counselors who were older and who had higher levels of burnout. Counselor gender, race, certification status, and experience were not found to be significantly associated with counselor rapport.
30

The Relation of Norms and Memory for Emotion

Hiles, Amanda Roberta 11 April 2006 (has links)
The SWB measures have been shown to converge and diverge in interesting ways. Specifically, people memory for emotion differs from their momentary experience of emotions. Systematic factors such as norms guide the reconstruction of memories for past emotions. Several studies have shown that norms play a role in shaping reports of emotions. However, these studies have only used global and retrospective reports of emotion, or have not measured norms directly. The current study directly examined the level at which norms operate on emotions current mood and recalled emotions using the experience sampling method. Results indicate that norms operate on recalled emotion and not momentary emotion. Further, the correlation between recalled emotion and norms is stronger for pleasant than unpleasant emotion.

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