Susceptibility of a spinon Fermi surface coupled to a U(1) gauge field

We study the theory of a U(1) gauge field coupled to a spinon Fermi surface. Recently this model has been proposed as a possible description of the organic compound $\kappa-(BEDT-TTF)_2 Cu_2 (CN)_3$. We calculate the susceptibility of this system and in particular examine the effect of pairing of the underlying spin liquid. We show that this proposed theory is consistent with the observed susceptibility measurements.Comment: 5 pages, 4 figure

Investigating The Impact Of Offset Fracture Hits Using Rate Transient Analysis In The Bakken And Three Forks Formation, Divide County, North Dakota

The common development plan for operators in the Williston Basin has been to initially drill and complete one well in order to hold a 1280 acre spacing unit. Once acreage is secure across the asset, operators return to each spacing unit and drill infill wells. By the time infill wells are drilled, reservoir depletion from the original (parent) well can be observed within the spacing unit. Reservoir depletion increases the likelihood of existing wells experiencing inter- communication when infill wells are hydraulically fractured. Such inter-well communication, or frac-hits, often have detrimental effects on existing wells. As such, understanding the effect of well timing and spacing on overall spacing unit performance is of critical importance when determining an appropriate development plan. Rate transient analysis (RTA) is an effective way to quantify the impact of offset frac hits, providing changes in reservoir properties such as stimulated rock volume (SRV) and well productivity. This study used pseudo normalized pressure versus material balance square root of time plots in order to determine the impact of offset frac hits on existing wells. The slope of the superposition time plot is inversely proportional to A_c â(k ) , which offers a good metric for early time well productivity and completion effectiveness. Superposition time plots were created, and a production lookback was performed on 71 operated wells in northern Divide County, North Dakota. Changes observed in reservoir properties and production performance were used to determine appropriate well spacing and infill timing. In addition, this study conducted a look back economic evaluation for 71 wells and 15 spacing units, using current commodity pricing, to assess the investment efficiencies of each project. Results from rate transient analysis, production analysis, and the economic evolution indicate that 5 â 6 wells is the optimal wells spacing per 1280 acre spacing unit within the study area

Use of Remote Sensing, Hydrologic Tree-Ring Reconstructions, and Forecasting for Improved Water Resources Planning and Management

Uncertainties were analyzed in three areas (remote sensing, dendroclimatology, and climate modeling) relevant to current water resources management. First, the research investigated the relationships between remotely sensed and in situ Snow Water Equivalent (SWE) datasets in three western U.S. basins. Agreement between SWE products was found to increase in lower elevation areas and later in the snowpack season. Principal Components Analysis (PCA) revealed two distinct snow regions among the datasets and Singular Value Decomposition (SVD) was used to link both data products with regional streamflow. Remotely sensed SWE was found to be sufficient to use in statistically based forecast models in which magnitude did not affect results. Second, the research investigated the dendroclimatic potential of a critical flood control and hydropower region in the southeastern U.S. (Tennessee Valley) using climate division precipitation and regional tree-ring chronology datasets. Tennessee Valley May–July precipitation was reconstructed from 1692 to 1980 (289 years) using a stepwise linear regression model (R2 = 0.56). Weibull analysis illustrated that the Tennessee Valley reconstruction model developed generally underestimated extreme precipitation and overestimated average precipitation. The longest May–July drought occurred over 10 consecutive years (1827–1836). Instrumental records indicated that the two most recent droughts (1985–1988 and 2006–2008) ranked second and third in severity in the past three centuries. Third, past, present, and future patterns and extremes in streamflow within the North Platte River Basin were investigated. A streamflow reconstruction dating back to 1383 using tree rings was created to provide a proxy for the long-term variability in the region. Projected streamflow datasets from the Community Climate System Model (CCSM) were gathered to acquire future insight of the hydroclimatic variability within the North Platte River Basin (NRPB). Drought analysis revealed that 2002–2008 was one of the driest periods in the past 600 years. Multiple CCSM projections suggest that in the future, drier (5th percentile) years will become wetter relative to 1970–1999 CCSM hindcasts. Future average (50th percentile) and wet (95th percentile) years may yield statistically higher streamflow compared to those seen in the historical (1383–1999) record, suggesting potential anthropogenic influence beyond the historic natural variability

Mechanisms of Estrogen Receptor Alternative Splicing and the Consequences for Aging in the Female Brain

The advances in healthcare and scientific knowledge have resulted in longer life expectancies in women. These advanced ages in women now means that they are experiencing the effects of age-related changes in the body for much longer periods of time, mainly reproductive senescence, resulting in the loss of circulating ovarian hormones. The age at which menopause occurs has not changed, resulting in women now living over a third of their lives in a postmenopausal state. The major circulating estrogen produced by the ovaries, 17β-estradiol (E2), has many homeostatic effects in the body like neuroprotection and cardioprotection. Hormone replacement therapy (HT) was to become the standard in treating women undergoing reproductive senescence in order to abrogate the negative effects associated with the decline in circulating E2, however adverse effects of HT were observed mainly women who were at least 10 years removed from menopause. These findings led to the idea of a therapeutic window in which ET is beneficial, known as the “timing hypothesis”, pointing to age-related adjustments that occur during and after this critical period of declining E2 levels. E2 is known to regulate transcription through an important class of nuclear steroid receptors called estrogen receptors (ERs). ERβ mediate the actions of E2 upon binding through interactions within the promoter region of ER-regulated genes and is subject to alternative splicing. It is through this process that ERβ splice variants arise altering the receptor function and responsiveness to E2 in the brain. These observations led to the hypothesis that aging and diminished E2 levels affect the alternative splicing of ERβ in the aged female brain through altered expression of ER-regulated splicing factors. ERβ alternative splice variants were measured in the brain of young and aged female rats who were subjected to increasingly longer periods of hormone deprivation. In vitro data from brain-derived cell lines also provided mechanistic answers to how ERβ is alternatively spliced in the brain. This dissertation work contributes to our overall understanding of ERβ in the context of its expression and possible function in the aging female brain

Master of Science

thesisDuring reconstructive and free tissue transfer surgeries it is often necessary to cut and reattach multiple vessels. The current method of vessel anastomosis is traditional hand suturing. The scope of this venture is to create a commercially available vascular coupling device (VCD) that would allow surgeons to quickly attach vessels together. The VCD is designed to increase reliability and reduce the amount of time spent on connecting two vessels. Hand suturing a vessel is time consuming (20-30 minutes) and difficult (requires a skilled surgeon). The method that has been developed can reduce the amount of time in the operating room by 75% and provides a superior anastomosis. In order to reach this level of improvement a set of installation tools was developed. These tools compliment the VCD and perform the necessary functions to consistently anastomise vessels. These tools were developed using laser machining techniques developed for this project. The laser manufacturing techniques allowed for the rapid development of the VCD and its supporting tools. With further development the VCD will become an important tool for the microsurgical community

Exhumation of the Lesser Himalaya of Northwest India : Zircon U-Pb and (U-Th)/He constraints and implications for the Neogene seawater evolution

The kinematic and exhumational evolution of the Lesser Himalayan (LH) of Northwest India remains a topic of debate; the resolution of which may provide insight into the relationship between the weathering of chemically distinct Himalayan source rocks and observed shifts in global seawater chemistry. Two contrasting models have been proposed to explain the origin of the now southward dipping Tons Thrust, which separates the LH into the inner Lesser Himalaya (iLH) of late Paleo-Mesoproterozoic rocks and the younger outer Lesser Himalaya (oLH) of low grade Cryogenian to Cambrian metasedimentary rocks. The initial exhumation of Cambrian black shales of the oLH anomalously enriched in 187Os has been proposed to drive a rapid increase in global seawater 187Os/188Os at ~16 Ma, thus testing these contrasting tectonic models is critical to elucidate this proposed relationship. While one model suggests that the Tons Thrust shared an original decollement with the South Tibetan Fault System and that the oLH is a far-traveled klippe emplaced against the iLH during the Eocene-Oligocene prior to out-of-sequence activation of the Main Central Thrust (MCT), a second model suggests that the oLH is a short-traveled, in sequence thrust sheet emplaced in the Late Miocene, post-dating movement along the MCT. Given the temporal discrepancy for oLH emplacement of at least 14 Myrs and broad constraints on the thermal history of the oLH, iLH, and MCT hanging wall, zircon (U-Th)/He (ZHe) thermochronology can effectively be used to test these hypotheses and reconstruct the exhumational evolution of the LH. New bedrock and foreland basin ZHe data support the short-traveled oLH model and provide direct evidence for rapid exhumation and southward advancement of thrusting away from the Main Central Thrust (MCT) to the Tons Thrust starting at ~16 Ma, resulting in a shift in exhumation to LH strata highly enriched in Os and relatively less in Sr compared to MCT hanging-wall rocks. This shift in exhumation directly corresponds to coeval shifts in global 187Os/188Os and 87Sr/86Sr seawater records. While these seawater records are commonly utilized as deep-time proxies to track global silicate weathering intensity responsible for CO2 drawdown and climatic cooling, our data, coupled with mass balance box-modeling, indicates that regional weathering of isotopically unique source rocks can drive these seawater records independently from shifts in global-scale weathering rates, consequently hindering this utility of these records.Geological Science

Timing and genesis of fractures in the Niobrara Formation, northeastern Front Range and Denver Basin, Colorado

Department Head: Sally J. Sutton.2010 Summer.Includes bibliographical references (pages 139-152).Naturally-occurring fractures in foreland basins, particularly in self-sourced resource plays, are critical to the production of hydrocarbons from low permeability reservoirs. Both shear and extensional fractures commonly cause reservoir anisotropy as well as providing critical tests of tectonic hypotheses. The objective of this research is to determine the mechanisms and timing of naturally-occurring fractures in the upper Cretaceous Niobrara Formation along the northeastern Front Range and in the Denver Basin of the Rocky Mountain Foreland. Previous hypotheses for the origin of fractures within the Denver Basin have focused largely on mechanisms invoking basement reactivation either by vertical block motion or by Laramide subhorizontal shortening. Contrasting hypotheses include multidirectional slip, regional and/or local detachment, and post-Laramide extension in the direction of previous compression. This study analyzes the kinematics, modes and mechanisms of deformation in the Niobrara Formation from fractures examined along the northeastern Front Range and from faults identified in 3D seismic data from the Denver Basin. Surface fracture data collected from 61 locations include minor faults, joints, calcite-filled fractures, and pressure solution stylolites. Subsurface data includes two 3D seismic surveys (Sooner Field and Dana Point) were fault geometries were examined. In outcrops, ideal σ1 analysis of strike–slip and thrust fault data document a subhorizontal Laramide compression with an average attitude of 086°-08°. Normal faults identified through the study are highly variable with an average slip direction of 183°- 73°. Normal dip-slip reactivation of right-lateral shear planes indicates normal faults are younger. Two joint systems are observed throughout the study area with J1 joints averaging 078° and later J2 joints averaging 171°. Subsurface 3D seismic data show listric and planar normal fault sets cut the Niobrara and lower Pierre formations. Calculated fault dip angles at Sooner Field average 8°, and those at Dana Point average 27°. These low fault dip angles suggest layer-parallel detachment, but diverse fault strikes are problematic and suggest multiple slip directions. No basement-to-Cretaceous faults were identified in either volume, casting doubt on basement reactivation hypotheses. Fracture sets in the Niobrara Formation show evidence for four different fracture mechanisms. Initial faulting generated by Laramide subhorizontal compression (086°) was followed by later, but still Laramide, ENE- to E-W-striking J1 splitting joints. Post- Laramide extension is indicated by NNW to N-S-striking J2 joints. Lastly, low-angle listric and planar normal faults in seismic data are interpreted to be post-Laramide. They were probably caused by local detachment, but their mechanisms and timing require further investigation

Hire, Train, Retain: Addressing the Arkansas Special Education Teacher Shortage

The purpose of this mixed methods study was to identify factors affecting special education teacher recruitment and retention throughout the Northwest Arkansas/River Valley region. This study contains both quantitative and qualitative survey data from 30 public school districts and 401 special education teachers currently serving in the field. The survey, deployed over a 30-day period, contained a series of multiple choice, Likerttype, and open-ended questions that were analyzed by the researcher to answer seven research questions. The results of this study indicate that perceptions of job commitment do not differ significantly based on the demographic characteristics of special educators. Yet, data did suggest that a special educator’s teaching role does play a role in their level of job commitment. According to the data, special educators serving in the self-contained teaching role were found to be more committed than those teachers serving in inclusion. This study suggests that special educators who are satisfied with their current position are more committed to their jobs and will teacher longer. However, stress was negatively correlated with both job satisfaction and career longevity. Data also indicates that paperwork issues, workload issues, lack of administrative support, and low salaries were the most prevalent reasons given for wanting to exit the profession. Less than 50% of respondents indicated that their intent was to stay in the profession for longer than three to five years. Of those wanting to leave the field of special education, the most frequently selected reasons were retirement, to teach in general education, and to seek employment outside of the field of education. To recruit and retain more special educators, respondents suggest offering additional financial incentives, which the majority of schools within this region do not currently offer. Increased support and viii paperwork assistance were also frequently suggested ways to improve recruitment and retention efforts. Additionally, this study found that special educators are often intrinsically motivated and enter the profession due to their love for special education students

Effects of Dietary Conjugated Linoleic Acid Supplementation on Bovine Oocyte Lipid Metabolism, Lipid Composition and Embryo Cryotolerance

Variation in cryotolerance exists between embryos from different animal breed, species and management conditions. Reduced tolerance to chilling and cryotolerance of oocytes and embryos has been associated with greater cytoplasmic lipids (Kim et al., 2001; Seidel, 2006). Previous studies in the cow have demonstrated nutrition-induced modification of follicular components. Trans-10, cis-12 conjugated linoleic acid (CLA) was identified as a potent inhibitor of milk fat synthesis in lactating cows (Baumgard et al., 2000) and inclusion of CLA in bovine embryo culture medium improved post-thaw embryo survival (Pereira et al., 2007). Dietary supplementation of cows with CLA could alter oocyte fatty acid metabolism, oocyte lipid composition and embryo cryotolerance, and responses may be different between Bos indicus and Bos taurus breeds of cattle. Therefore, a series of experiments were conducted to evaluate effects of dietary CLA supplementation of cows on (1) milk fat depression in lactating Holstein cows, (2) follicle and oocyte production and lipid content of oocytes from Brahman and Holstein cows, (3) mRNA expression of genes involved in lipid metabolism in oocytes from Brahman and Holstein cows and (4) cryosurvival of in vitro-produced embryos from CLA-supplemented oocyte donor cows. Milk fat was depressed by 10.1% in lactating Holstein cows fed CLA. Follicle, oocyte and embryo production of cows were not influenced by CLA supplementation. Dietary supplementation of cows with CLA before oocyte collection did not influence cryotolerance of in vitro-produced embryos or expression of genes in oocytes involved in lipid metabolism. Lipid content of oocytes was not influenced by CLA supplementation. The ovarian response to dietary CLA was similar among Brahman, Holstein and crossbred beef cows. The highly regulated mechanisms involved in fatty acid uptake by ovarian components may help explain the lack of ovarian response to dietary CLA in the current study