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  • ItemOpen Access
    Effects of background winds and temperature on bores, strong wind shears and concentric gravity waves in the mesopause region
    (Colorado State University. Libraries, 2009) Yue, Jia, author; She, Chiao-Yao, advisor; Reising, Steven C., advisor
    Using data from the CSU sodium lidar and Kyoto University OH airglow imager at Fort Collins, CO, this thesis provides a comprehensive, though qualitative, understanding for three different yet related observed fluid-dynamical phenomena in the mesopause region. The first project involves the convection-excited gravity waves observed in the OH airglow layer at 87 km. Case study on May 11, 2004 is discussed in detail along with statistical studies and a ray-tracing modeling. A single convection source matches the center of the concentric gravity waves. The horizontal wavelengths and periods of these gravity waves were measured as functions of both radius and time. The weak mean background wind between the lower and middle atmosphere determines the penetration of the gravity waves into higher altitude. The second project involves mesospheric bores observed by the same OH imager. The observation on October 9, 2007 suggests that when a large-amplitude gravity wave is trapped in a thermal duct, its wave front could steepen and forms bore-like structure in the mesopause. In turn, the large gravity wave and its bore may significantly impact the background. Statistical study reveals the possible link between the jet/front system in the lower atmosphere and the large-scale gravity waves and associated bores in the mesopause region. The third project involves the relationship between large wind shear generation and sustainment and convective/dynamic stabilities measured by the sodium lidar at the altitude of 80-105 km during 2002-2005. The correlation between wind shear, S, and Brunt-Vaisala frequency, N suggests that the maximum sustainable wind shear is determined by the necessary condition for dynamic instability of Richardson number, leading to the result that the maximal wind shear occurs at altitudes of lower thermosphere where the atmosphere is convectively very stable. The dominate source for sustainable large windshears appears to be the semidiurnal tidal-period perturbations with shorter vertical wavelengths and greater amplitude.
  • ItemOpen Access
    Epidemiology and veterinary public policy
    (Colorado State University. Libraries, 2008) Zepeda Sein, Cristóbal Andrés, author; Salman, Mo, advisor
    Official Veterinary Services are increasingly required to base veterinary public policy decisions on scientific grounds, epidemiology and risk analysis play an important role in shaping these decisions. A formal, in-depth analysis of the multiple interactions between epidemiology, risk analysis and veterinary public policy was conducted to enable decision-makers to direct resources more efficiently and facilitate compliance with international agreements, in particular the Agreement on the Application of Sanitary and Phytosanitary Measures (SPS) of the World Trade Organization. The SPS Agreement recognizes the World Organization for Animal Health (OIE) as the international organization responsible for developing animal health standards. The OIE's Terrestrial Animal Health Code contains scientifically based recommendations for international trade in animals and animal products. However, to date, these recommendations have not been assessed from a risk-based perspective. The study is divided in two major sections: (1) the role of epidemiology in veterinary public policy and (2) the application of risk-based approaches to the assessment of international animal health standards. The first section addresses the international framework, risk analysis and its use worldwide, and the development of international standards. The second section focuses on quantitative risk assessment approaches for the international movement of animals and products, as well as the application of compartmentalization to aquaculture production systems emphasizing the use of a HACCP approach to biosecurity.
  • ItemOpen Access
    The animal paradox: animals, sovereignty and the politics of eating
    (Colorado State University. Libraries, 2008) Young, Katherine E., author; Macdonald, Bradley J., advisor; Chaloupka, William J., advisor
    Looking at the history of political thought, it becomes clear that animals are the decisive political exception in Western politics. It is not that animals are simply excluded in the history of political thought, however, but that they are "inclusively excluded," demarcating the constitutive outside of politics. In other words, animals are characterized as unable to differentiate themselves from their world because they are irrational, speechless and/or appetite driven, and for these reasons, they function as markers for the state of nature and the exit point of politics. Expanding the Italian political theorist Giorgio Agamben's work on the state of exception, it appears that the sacrifice of animal bodies-not simply the idea of animality-becomes vital to sustaining key political concepts like sovereignty, democracy and rights. More specifically, there is an underlying politics of eating that nourishes the Western canon. In the simplest terms, the politics of eating is a secular transubstantiation of sovereign power, in which meat is the material good (signifying the good life) that is consumed by political subjects to mitigate the tension between individual and state sovereignty. Of course, this economy of relations is exacerbated under late capitalism. With the advent of the animal rights movement, however, animals are now drawn into this anthropological political space. Yet, because so many animal advocates (scholars and activists alike) embrace traditional understandings of rights, democracy and sovereignty, they inadvertently support juridical forms that undermine their projects. With this in mind, and given the exceptional political state of animals, it is timely to think about new political strategies that take seriously the irony of animals within the larger context of politics as well as restore the public spectacle of meat, in order to reveal and disrupt the sacrificial politics of eating, which includes both humans and animals.
  • ItemOpen Access
    Characterization of integrated optical waveguide devices
    (Colorado State University. Libraries, 2008) Yuan, Guangwei, author
    At the Optoelectronics Research Lab in ECE at CSU, we explore the issues of design, modeling and measurement of integrated optical waveguide devices of interest, such as optical waveguide biosensors and on-chip optical interconnects. A local evanescent-field array coupled (LEAC) sensor was designed to meet the needs for low-trace biological detection without florescent chemical agent aids. The measurement of LEACs sensor requires the aid of either a commercial near-field scanning optical microscope (NSOM) or new proposed buried detector arrays. LEAC sensors were first used to detect pseudo-adlayers on the waveguide top surface. These adlayers include SiNx and photoresist. The field modulation that was obtained based on NSOM measurement was approximately 80% for a 17 nm SiNx adlayer that was patterned on the waveguide using plasma reactive ion etching. Later, single and multiple regions of immunoassay complex adlayers were analyzed using NSOM. The most recent results demonstrated the capability of using this sensor to differentiate immunoassay complex regions with different surface coverage ratio. The study on buried detectors revealed a higher sensitivity of the sensor to a thin organic film on the waveguide. By detecting the optical intensity decay rate, the sensor was able to detect several nanometer thick film with 1.7 dB/mm/nm sensitivity. In bulk material analysis, this sensor demonstrated more than 15 dB/mm absorption coefficient difference between organic oil and air upper claddings. In on-chip optical interconnect research, optical waveguide test structures and leaky-mode waveguide coupled photodetectors were designed, modeled and measured. A 16-node H-tree waveguide was used to deliver light into photodetectors and characterized. Photodetectors at each end node of the H-tree were measured using near-field scanning microscopy. The 0.5 micrometer wide photodetector demonstrated up to 80% absorption ratio over just a 10 micrometer length. This absorption efficiency is the highest among reported leaky-mode waveguide coupled photodetectors. The responsivity and quantum efficiency of this photodetector are 0.35 A/W and 65%, respectively.
  • ItemOpen Access
    Characterizing the fluorescence intermittency of individual cadmium selenide/zinc sulfide quantum dot clusters with spatially correlated single molecule fluorescence spectroscopy and atomic force microscopy
    (Colorado State University. Libraries, 2008) Yu, Ming, author; Van Orden, Alan K., advisor
    In this thesis, I describe work done to study the optical behaviors of CdSe/ZnS quantum dots, especially the fluorescence blinking behavior of small quantum dot clusters. QDs have unique optical properties that impart several key advantages over molecular dyes. However, when examined at the single-molecule level, QDs emission exhibit novel fluorescence intermittency, or "blinking," behavior. This blinking is believed to be caused by trapping and de-trapping of the photoexcited carriers, causing the QDs to fluctuate between emissive and non-emissive states. A spatially correlated single molecule fluorescence spectroscopy and atomic force microscopy (AFM) apparatus was used to carry out these studies. Single molecule spectroscopy examines the blinking behavior of individual, isolated QDs and QD clusters, while the AFM images the nanometer scale topography of the particles. When multiple isolated QDs were probed simultaneously, the fluorescence behavior was consistent with independent blinking of the individual QDs. However, when close-packed QD clusters were probed, the fluorescence intermittency became much more rapid and intense than could be explained by the summation of multiple particles blinking independently. This suggests when the small QDs aggregate together, they become electronically coupled in some way that enhances the fluorescence blinking. Subsequently, we studied variations of the emission wavelengths of isolated small QD clusters possessing the enhanced blinking behavior. The emission wavelength of the coupled enhanced blinking is red shifted relative to that of normal blinking. We propose that red-shifting in emission is one of the characteristics of electronic coupling in the QD clusters and resulted from the quantum confinement Stark effect. In the following chapters, environment and substrate dependence were also studied. Compared with ambient air, dry nitrogen decreases the population, intensity and/or durations of "on" times. Both CTAB- and Mg 2+-mica substrates quench the fluorescence of single QDs and QD clusters, which is due to the dissociation of electron hole pairs of excited QDs by the electron attractive sites in CTAB molecules and Mg2+ ions.
  • ItemOpen Access
    Enantioselective rhodium-catalyzed [2+2+2] and [4+2+2] cycloaddition reactions of alkenyl heterocumulenes: applications to alkaloid synthesis
    (Colorado State University. Libraries, 2009) Yu, Robert Tzu Hsiang, author; Rovis, Tomislav, advisor
    An intermolecular rhodium-catalyzed [2+2+2] cycloaddition of alkenyl isocyanates and internal alkynes has been developed. In the presence of a catalytic amount of [Rh(C2H4)2Cl]2 and P(4-MeO-C6H4)3, the cycloaddition produces substituted indolizinones and quinolizinones with newly formed sp 3-stereocenters. Depending on the alkynyl partners, a CO migration process can be involved during the cycloaddition to furnish cycloadducts possessing vinylogous amide functionality. The use of TADDOL-based phosphoramidite ligands on rhodium allows for the incorporation of terminal alkynes in a highly enantioselective [2+2+2] cycloaddition with alkenyl isocyanates. Terminal alkyl alkynes provide bicyclic lactams, while the use of aryl alkynes provides complementary access to vinylogous amides through a CO migration process. Product selectivity seems to be governed by a combination of electronic and steric factors, with smaller and/or more electron-deficient substituents favoring lactam formation. The synthetic utility is demonstrated in an expedient asymmetric total synthesis of the alkaloid (+)-lasubine II. A highly enantioselective rhodium-catalyzed [2+2+2] cycloaddition of terminal alkynes and alkenyl carbodiimides has been realized. The cycloaddition with aryl alkynes provides complementary selectivity to the reaction previously described using isocyanates. In addition, this reaction demonstrates the feasibility of olefin insertion into carbodiimide-derived metalacycles, and provides a new class of chiral bicyclic amidines as the major products. A new catalyst system has been realized. The use of chiral biphenyl-based phosphoramidite ligands on rhodium provides an efficient cycloaddition between terminal alkyl alkynes and alkenyl isocyanates. The cycloaddition proceeds through a CO migration pathway, and generates various 5-alkyl indolizinone products with high enantiomeric excess. A four-step asymmetric synthesis of indolizidine (-)-209D has been achieved. A highly enantioselective rhodium-catalyzed [4+2+2] cycloaddition of terminal alkynes and dienyl isocyanates has been developed. The cycloaddition provides a rapid entry to highly functionalized and enantioenriched bicyclic azocines. This reaction represents the first [4+2+2] cycloaddition strategy to construct nitrogen-containing eight-membered rings.
  • ItemOpen Access
    African-American women college and university presidents: their role, experiences, challenges and barriers
    (Colorado State University. Libraries, 2008) Woodard, Sophia J., author; Davies, Timothy G., advisor
    The purpose of this study was to examine four phenomena: role, experiences, challenges, and barriers of African-American women college and university presidents with a particular focus on the role based on the social conscious concept of "race upliftment" as espoused by Dr. W.E.B. DuBois and other African American scholars of the early 20th century. The review of literature suggests that there is a tendency to advocate for race upliftment primarily when leading an African-American institution or an Historically Black College and University (HBCU). As a qualitative phenomenological study, in-depth personal and telephone one to two hour interviews were conducted with eight African-American women college and university presidents of two and four-year institutions. Each interview was tape-recorded with the full permission of the president. A demographic questionnaire was completed by each president prior to conducting the interview. All eight recorded tapes were transcribed and the data analysis process involved six major steps based on Creswell (1994). The qualitative software HyperRESEARCH was used to assist in analyzing and coding the data, and in compiling the qualitative report. Reading and memoing were used for code and theme development, and a reflexive journal, member checking, clarifying research bias and peer review were used for validity and trustworthiness. The findings of this study revealed that role plays a significant component for these women and is categorized into several areas that include: (1) nurturer and protector of students; (2) fiscal manager; (3) values and skills practitioner; (4) spiritual practitioner and servant; and (5) communications expert. Their work in role directly impacts and influences how they view and serve in their role as leaders. In fact, these African-American women college and university presidents developed many of their concepts of role based on the multi-faceted experiences they encountered both on their journey to the presidency and in this journey. Many of their experiences encompassed their formative years of education and training/rearing in their homes and communities, the educational journeys they traveled through college and graduate school, as well as the varied professional encounters in academia prior to becoming presidents. The collective energy of these experiences were an exciting and foundational part of their leadership development and journeys to the presidency which were also consumed with challenges and barriers. These challenges and barriers were centered around five specific areas that comprised the challenges of leadership: (1) addressing and resolving fiscal insolvency; (2) personal challenges such as parenting roles and living apart from family members(children and husbands); (3) managing health and wellness; (4) gender, race and age disparity; and (5) professional challenges such as status quo issues, college-wide communication issues, dealing with alumni concerns and problems with overbearing board-of-trustee members. In essence, the role, experiences, challenges and barriers that emerged from the data (voices) of these African-American women college and university presidents comprise the journey they traveled in becoming and being president.
  • ItemOpen Access
    Estimation for Lévy-driven CARMA processes
    (Colorado State University. Libraries, 2008) Yang, Yu, author; Brockwell, Peter J., advisor; Davis, Richard A., advisor
    This thesis explores parameter estimation for Lévy-driven continuous-time autoregressive moving average (CARMA) processes, using uniformly and closely spaced discrete-time observations. Specifically, we focus on developing estimation techniques and asymptotic properties of the estimators for three particular families of Lévy-driven CARMA processes. Estimation for the first family, Gaussian autoregressive processes, was developed by deriving exact conditional maximum likelihood estimators of the parameters under the assumption that the process is observed continuously. The resulting estimates are expressed in terms of stochastic integrals which are then approximated using the available closely-spaced discrete-time observations. We apply the results to both linear and non-linear autoregressive processes. For the second family, non-negative Lévy-driven Ornestein-Uhlenbeck processes, we take advantage of the non-negativity of the increments of the driving Lévy process to derive a highly efficient estimation procedure for the autoregressive coefficient when observations are available at uniformly spaced times. Asymptotic properties of the estimator are also studied and a procedure for obtaining estimates of the increments of the driving Lévy process is developed. These estimated increments are important for identifying the nature of the driving Lévy process and for estimating its parameters. For the third family, non-negative Lévy-driven CARMA processes, we estimate the coefficients by maximizing the Gaussian likelihood of the observations and discuss the asymptotic properties of the estimators. We again show how to estimate the increments of the background driving Lévy process and hence to estimate the parameters of the Lévy process itself. We assess the performance of our estimation procedures by simulations and use them to fit models to real data sets in order to determine how the theory applies in practice.
  • ItemOpen Access
    Enhancing natural treatment systems by utilizing water treatment residuals
    (Colorado State University. Libraries, 2008) Yarkin, Mustafa, author; Carlson, Kenneth H., advisor
    The current project envisions the application of riverbank filtration (RBF) and aquifer recharge and recovery (ARR) in series as preliminary treatment steps of a multi-barrier treatment approach for the City of Aurora's Prairie Waters Project. The primary focus of the project is the removal of phosphorus, nitrogen, and carbon from the source water resulting in biologically stable water that can be stored in a terminal reservoir. In addition to nutrients, perchlorate and three commonly used pesticides, atrazine, alachlor, and metolachlor have been studied in terms of removal with the RBF and ARR systems. Aluminum based water treatment residual (WTR) was considered along with other sorbents for enhanced phosphorus removal. The experimental studies include the monitoring of an RBF field site and pilot columns that simulate RBF and ARR systems. Possible benefits of WTR as an amendment were tested by amending a column with 30% WTR under RBF and ARR conditions. Also an application scenario of RBF followed by a WTR amended ARR infiltration basin and ARR was simulated by a column study. Results of the studies indicated that the RBF and ARR systems are insufficient to provide sustainable phosphorus removal. Phosphorus removal mechanism is limited by the sorption capacity of the alluvial sand and minor biological activity. Use of the WTR amendment reduced phosphorus levels to less than the method detection limit of 0.03 mg/L with a high adsorption capacity. The ARR system in sequential RBF-ARR application suffers from the lack of labile organic carbon and therefore microbially mediated treatment processes are limited. Amending the infiltration of the ARR system with organic carbon rich WTR can promote biological activity, thus allowing further biodegradation of contaminants. Results of the study indicated that the RBF system is a sustainable barrier for nitrate removal while labile carbon limited ARR cannot achieve significant nitrate removal. To use the ARR system as a secondary barrier for nitrate, a labile carbon source should be introduced to the system. WTR was used as a supply of organic carbon to the ARR system and the experimental studies indicated that, once optimized, WTR can promote biological denitrification through the ARR system. The field and column studies also showed that both RBF and ARR can achieve perchlorate removal as long as sufficient electron donating compounds (e.g. organic carbon) are present in the environment. It has also been observed that the ability of RBF and ARR systems to remove alachlor and metolachlor is limited by the biodegradation through the alluvial sand while they achieve sustainable atrazine removal. WTR was tested as an amendment alternative the ARR infiltration basin. Concentrations of selected pesticides were reduced to the method detection limit of 0.3 μg/L during 1-foot 30% WTR amended column treatment with the residence time of 1.25 days under both abiotic and biotic conditions. The overall study suggested that once the source and type of the WTR was selected, the optimum amount of WTR can be obtained by adjusting the application ratio and the media depth for the efficient removal of all contaminants of concern.
  • ItemOpen Access
    Combinatorial discovery and optimization of novel metal oxide materials for photoelectrolysis using visible light
    (Colorado State University. Libraries, 2008) Woodhouse, Michael, author; Parkinson, Bruce, advisor
    Efficient and inexpensive production of hydrogen from water and sunlight has been the "holy grail" of photoelectrochemistry since Fujishima and Honda first demonstrated the feasibility of the process by illuminating TO2 single crystals with UV light. While it was a great proof of concept, a more suitable material will most likely be an oxide semiconductor containing multiple metals that will each contribute to the required properties of stability, light absorption, and being catalytic for hydrogen or oxygen evolution. Therefore we developed a high throughput combinatorial approach to prepare overlapping patterns of metal oxide precursors onto conducting glass substrates that can be screened for photolectrolysis activity by measuring the photocurrent generated by rasterng a laser over the materials while they are immersed in an electrolyte. A ternary oxide containing cobalt, aluminum and iron, and not previously known to be active for the photoelectrolysis of water, was identified using the combinatorial technique. The optimal composition and thickness for photoelectrochemical response of the newly identified material has been further refined using quantitative ink jet printing. Chemical analysis of bulk and thin film samples revealed that the material contains cobalt, aluminum and iron in a Co3O 4 spinel structure with Fe and Al substituted into Co sites with a nominal stoichiometry of Co3-x-yAlxFeyO4 where x and y are about 0.18 and 0.30 respectively. The material is a p-type semiconductor with an indirect band gap of around 1.5 eV, a value that is nearly ideal for the efficient single photoelectrode photoelectroylsis of water. Photoelectrochemical measurements indicate that the material has a respectable photovoltage but the photocurrent is limited by the slow kinetics for hydrogen evolution. This new cobalt iron aluminum oxide is most likely not the "holy grail" of photoelectrochemistry that we seek, but our methodology gives a rational approach for future materials discovery and optimization.
  • ItemOpen Access
    Indirect electrochemical detection of DNA hybridization based on catalytic oxidation of cobalt(II) and concentration gradient formation in redox conducting polymers
    (Colorado State University. Libraries, 2008) Xue, Di, author; Elliott, C. Michael, advisor
    Since the new concept was introduced back in 1993, efforts to develop electrochemical methods for detecting nucleic acid hybridization (e.g., DNA) have mushroomed. Compared with nearly all other analytical techniques, electrochemical instrumentation is inexpensive, robust, and relatively simple to operate. The first part of the dissertation (Chapter 1 to Chapter 4) describes the development of a novel electrochemical DNA sensor based on catalytic oxidation of a cobalt bipyridine "mediator molecule" on an ITO electrode. Interaction of the surface bound DNA probe with the DNA target results in formation of hybrid duplex, which subsequently brings redox catalyst molecules from solution to the electrode surface. The mode of selective catalyst binding is intercalation between base pairs of ds-DNA. This surface-bound catalyst "turns on" the redox chemistry of the mediator molecule which is otherwise kinetically inert to oxidation on ITO. With this approach, we demonstrate detection of a 20-mer DNA target oligonucleotide at picomolar concentrations with outstanding signal-to-noise. The second part of our research (Chapter 5) mainly concerns redox polymer films containing permanently locked concentration gradients. Upon redox gradient formation, the conducting polymer displays interesting properties, such as solid diode behavior and electroluminescence. Previous methods explored drying and/or cooling the film to physically immobilize its gradient. Unfortunately, this preservation was temporary, and underwent degradation over time. Our work is aimed to overcome this limitation by covalently attaching counterions to the polymer backbone and thus permanently locking the redox gradients. Both parts of this dissertation utilize heteroleptic metal complexes possessing redox potentials close to zero (vs SSCE). Compounds with highly negative potentials are strongly reducing and highly positive potentials means strong oxidizing capabilities, which exerts strict requirements on supporting electrolytes and solvents, including high impurity, broad potential window as well as exclusion of environmental interference. Thus, the closer the potential to zero (vs SSCE), the more stable (electrochemically) the complex and the easier the electrochemical measurements.
  • ItemOpen Access
    Biochemical, biophysical and structural study of the nucleosome-MeCP2 complex
    (Colorado State University. Libraries, 2009) Yang, Chenghua, author; Luger, Karolin, advisor
    Methyl-CpG Binding Protein (MeCP2) is an abundant chromatin associated protein that is important in maintaining human health; mutations in this protein cause Rett Syndrome, a neurodevelopmental disease that is a common cause of mental retardation and autism in females. MeCP2 was initially identified as a protein that recognizes the genetic DNA methyl-CpG mark and it was thought to repress gene transcription by recruiting histone deacetylases. Recent studies show that MeCP2 can both repress and activate gene transcription. It also binds chromatin in the absence of the methylation mark, suggesting that its mode of action is more complex than previously assumed. The observation that MeCP2 compacts nucleosomal arrays in vitro and mediates silent chromatin loop formation in vivo suggests a novel mechanism by which MeCP2 regulates gene expression. To further characterize the interplay between MeCP2 and chromatin, it is important to understand the interactions between MeCP2 and nucleosomes, the fundamental component of chromatin. We used biochemical and biophysical approaches to study the interplay between MeCP2 and nucleosomes. Gel mobility assays showed that although MeCP2 can interact with a nucleosome with or without extra nucleosomal DNA, it has a higher affinity for nucleosomes with extra nucleosomal DNA. The N-terminal portion of human MeCP2 (amino acids 78-305) is sufficient to establish this interaction. Size-exclusion chromatography combined with multi-angle light scattering and fluoresecence resonance energy transfer (FRET) assays demonstrated that this interaction occurs at a 1:1 molar ratio and that MeCP2 brings the extra nucleosomal DNA ends in a closer proximity. Small angle X-ray scattering (SAXS) revealed the formation of a more compact complex when MeCP2 interacts with nucleosome with (versus without) extra nucleosomal DNA, indicating that the extra nucleosomal DNA is important in organizing the MeCP2-nucleosome complex. Our data suggest a model in which MeCP2 compacts chromatin by changing the extra nucleosomal DNA path. X-ray crystallography is also used to characterize the nucleosome-MeCP2 complex. Crystals of the nucleosomes with extra nucleosomal DNA in complex with MeCP2 were obtained and diffracted to 5.2 Ã…. Although MeCP2 dissociated from the crystals after soaking in cryo-protectant, the electron density map reveals the path of extra nucleosomal DNA which may be organized by MeCP2.
  • ItemOpen Access
    Asymmetric epoxidation of various olefins catalyzed by fructose- and glucose-derived ketones
    (Colorado State University. Libraries, 2009) Wong, On Lo Andrea, author; Shi, Yian, advisor
    Numerous laboratories have studied dioxirane- and oxaziridinium-mediated epoxidations during the past two decades. Many chiral ketone and iminium salt catalysts, bearing a wide variety of structural features, have been investigated. Out of the systems studied a fructose-derived ketone has been proven to be one of the most general and practical catalysts. This catalyst epoxidizes trans- and trisubstituted olefins in good yield and enantioselectivity, and it has been employed in the syntheses of many complex molecules. In efforts to expand the substrate scope a series of glucose-derived, oxazinolidine-bearing ketones were reported to be excellent catalysts for the epoxidation of conjugated cis-olefins. The stereodifferentiation in the epoxidation transition state originates from the attraction between the N-substituent of the oxazolidinone and the RÏ€ substituent on the olefin. The existence of this interaction was supported by the observation that 6-substituted chromenes were epoxidized with higher enantioselectivities than 8-substituted chromenes. Using this glucose-derived ketone system, substituted chiral styrene oxides could be obtained in 80-92% ee. Fluoroolefins were investigated as epoxidation substrates with several fructose- and glucose-derived ketone catalysts. A fluorine substituent was found to improve enantioselectivity in some cases but was detrimental to enantioselectivity in others. The substrate scope of a diacetate-containing ketone was expanded. High enantioselectivities were obtained for the epoxidation of trans- and trisubstituted olefins, and cis-olefins bearing a bulky substituent. The optical rotations of the resulting cis-epoxides were opposite to those obtained using glucose-derived ketones. 1,1-Disubstituted terminal olefins were epoxidized in good enantioselectivities with a glucose-derived morpholinone ketone. From the absolute configuration of the resulting epoxides, the major transition state appears to be a planar-like transition state. Also studied was a glucose-derived dimethylmorpholinone ketone that has the combined features of several of the previously studied ketones. This catalyst epoxidizes trans- and trisubstituted olefins in high enantoselectivities, but compared to the oxazolidinone-containing ketones gives slightly lower enantioselectivities with cis- and 1,1-disubstituted olefin substrates. Lastly, the epoxidation transition state model was studied using 18O-labeled ketone catalysts, and the results support the currently accepted transition state model.
  • ItemOpen Access
    Computational modeling of the lower cervical spine: facet cartilage distribution and disc replacement
    (Colorado State University. Libraries, 2009) Womack, Wesley J., author; Puttlitz, Christian, advisor
    Anterior cervical fusion has been the standard treatment following anterior cervical discectomy and provides sufficient short-term symptomatic relief, but growing evidence suggests that fusion contributes to adjacent-segment degeneration. Motion-sparing disc replacement implants are believed to reduce adjacent-segment degeneration by preserving motion at the treated level. Such implants have been shown to maintain the mobility of the intact spine, but the effects on load transfer between the anterior and posterior elements remain poorly understood. In order to investigate the effects of disc replacement on load transfer in the lower cervical spine, a finite element model was generated using cadaver-based Computed Tomography (CT) imagery. The thickness distribution of the cartilage on the articular facets was measured experimentally, and material properties were taken from the literature. Mesh resolution was varied in order to establish model convergence, and cadaveric testing was undertaken to validate model predictions. The validated model was altered to include a disc replacement prosthesis at the C4/C5 level. The effect of disc-replacement on range of motion, antero-posterior load distribution, total contact forces in the facets, as well as the distribution of contact pressure on the facets were examined, and the effect of different facet cartilage thickness models on load sharing and contact pressure distribution predictions were examined. Model predictions indicate that the properly-sized implant retains the mobility, load sharing, and contact force magnitude and distribution of the intact case. Mobility, load sharing, nuclear pressures, and contact pressures at the adjacent motion segments were not strongly affected by the presence of the implant, indicating that disc replacement may not be a significant cause of post-operative adjacent-level degeneration. Variation in articular cartilage distribution did not substantially affect mobility, contact forces, or load sharing. However, mean and peak contact pressure, contact area, and center of pressure predictions were strongly affected by the cartilage distribution used in the model. These results indicate that oversimplification of the cartilage thickness distribution will negatively affect the ability of the model to predict facet contact pressures, and thus subsequent cartilage degeneration.
  • ItemOpen Access
    Comparison of radiobiological endpoints in cells from CXB RI mice
    (Colorado State University. Libraries, 2008) Xiao, Guanxiong, author; Weil, Michael M., advisor
    Recombinant inbred (RI) mouse strains have been used both for trait cosegregation studies and genetic linkage analysis. They are created by using a breeding scheme that consists of a cross between two inbred mouse strains (progenitor strains) followed by at least 20 generations of brother-sister inbreeding. Thus, RI strains are inbred (homozygous at every locus) and derive roughly half their genome from each of the two progenitor strains. The CXB RI strain set consists of 13 RI strains derived from matings of BALB/c (C) and C57BL/6(B) mice. The CXB progenitor strains, BALB/c and C57BL/6, differ in their susceptibility to radiation-induced mammary tumors with BALB/c being susceptible and C57BL/6 being resistant. In part, the susceptibility difference can be explained by a polymorphism in the Prkdc gene which encodes the catalytic subunit of DNA-dependent protein kinase. However, other, as yet unknown, loci may be involved. The CXB RI strain set provides a useful tool to unravel the events that lead to radiation-induced mammary tumorigenesis and to understand the interrelationships of cellular radiobiological endpoints to one-another. We have generated fibroblast strains from each of the CXB RI strains and from the progenitor strains. The fibroblast strains were assayed for a number of radiobiological endpoints including clonogenic survival following acute and low dose-rate exposures, γ-H2AX focus formation and clearance following acute and low dose-rate exposures, and G2 chromosomal aberrations. In addition, we genotyped the strains for a polymorphism in the gene encoding the catalytic subunit of the DNA-dependent protein kinase, Prkdc. We then determined the correlations of different endpoints between the RI strains. As expected, clonogenic survival at low dose rates and following acute exposures were positively correlated. γ-H2AX focus formation at low dose rate correlated well with survival endpoints, particularly clonogenic survival under low dose rate irradiation and the surviving fraction at 2 Gy acute exposures. These three endpoints are all significantly associated with the Prkdc genotype with radiosensitive strains having the BALB/c genotype. The data we have collected provides a baseline description of cellular radio sensitivity in CXB fibroblasts. The approach used in this dissertation can be used to correlate these cellular radiobiological endpoints with susceptibility to clinically significant adverse outcomes from cancer radiotherapy, such as normal tissue injury and radiation-induced second cancers.
  • ItemOpen Access
    Spatial analyses of vector-borne disease risk for allocation of disease prevention and control resources
    (Colorado State University. Libraries, 2009) Winters, Anna M., author; Eisen, Lars, advisor; Moore, Chester G., advisor
    Vector-borne diseases are major threats to human health and well-being, inflicting enormous health and economic burden around the world. Meeting the challenge of emerging and resurging vector-borne diseases is a difficult undertaking as vaccines are limited, and future vaccine prospects are slow in coming. This underscores the importance of appropriately applied vector control and disease prevention efforts to decrease morbidity and mortality caused by vector-borne diseases. The objective of this dissertation was, therefore, to investigate spatially and temporally-explicit methods to enhance targeting of vector control and disease prevention efforts. Three diseases were investigated: West Nile virus disease in Colorado, USA; human plague in the West Nile region of Uganda; and dengue in Merida, Mexico. Various methods were explored to present spatial information representing risk of vector-borne diseases. Spatial models were developed indicating the risk of human exposure to WNV in the state of Colorado; and Yersinia pestis, the causative agent of plague, in Uganda. The resulting models provided robust validations indicating that the spatial risk maps contained useful information for disease prevention and control efforts. The final chapter expanded from spatially-explicit methods to also account for the temporal aspect of disease outbreaks or epidemics. This chapter describes the evaluation of the feasibility of an early detection system to identify outbreaks in a timely fashion in Merida, Mexico. The early detection system has the potential to provide Merida public health authorities with a resource to clearly recognize when the current dengue burden is exceeding historical norms and may be applicable and useful in other dengue endemic areas. The chapters composing this dissertation describe the application of cross-cutting methods used to determine spatial risk in different vector-borne disease systems. Furthermore, the methods used are applicable to the current public health situation where new vector-borne diseases are emerging and "old" diseases are resurging, further underscoring the importance of targeting limited public health resources.
  • ItemOpen Access
    Examination of molecular genetic factors involved in sensitivity to breast cancer following radiation exposure
    (Colorado State University. Libraries, 2008) Williams, Abby J., author; Ullrich, Robert L., advisor; Bailey, Susan M., advisor
    Understanding DNA repair is not only an important aspect of cell biology, but also has important implications for the field of carcinogenesis since cancer most likely occurs from genetic damage that occurs over one's lifetime. DNA repair needs to be accurate and efficient in order for a cell to maintain genomic stability, and defects in repair systems can result in radiosensitivity. Because radiation exposure, DNA repair deficiency and telomere malfunction are associated with cancer risk, we investigated Lymphoblastoid Cell Lines (LCLs) from breast cancer patients and controls for chromosomal radiosensitivity, relative telomere length, and gene expression changes. The importance of studying peripheral blood lymphocytes from cancer patients lies in the fact that minimally invasive techniques are lacking for the detection of individuals with high risk for cancer, and that telomere length has been proposed to be useful in this regard. Identification of radiosensitivity markers would be a valuable contribution for clinicians in hopes of avoiding excessive radiation or chemotherapy treatment given to patients. Failure to adequately repair DNA damage can result in cell suicide or halting of cell cycle progression in an attempt to allow repair mechanisms to operate. If damage persists, a cell can be pushed toward transformation and the pathway of carcinogenesis. A second aspect of the current work was to study the Homologous Recombination double-strand break repair protein, Rad51D. The emerging interrelations between DNA repair and telomere maintenance also prompted us to evaluate Rad51D's role in telomere function. The final aspect of this research involved examination of how DNA repair related proteins are linked to the indirect effect of ionizing radiation exposure known as the bystander effect (BSE). We are the first to demonstrate that DNA-PKcs and ATM are required to generate, but not receive, a bystander signal. We also show that mouse embryonic fibroblasts do not generate bystander signals to neighboring cells, while their adult cell counterparts do. Taken together, this work makes important contributions to our appreciation of the many and varied roles DNA repair related proteins play in maintenance of chromosomal integrity, proper telomere function, inhibition of carcinogenesis and now, regulation of the BSE.
  • ItemOpen Access
    Art-based narrative inquiry with Native American breast cancer survivors
    (Colorado State University. Libraries, 2008) Warson, Elizabeth, author; Kees, Natalie, advisor; Carlson, Laurie, advisor
    Background and aims. Breast cancer rates for American Indian and Alaska Native women are lower than any ethnic or racial group. This fact alone has contributed to the perception that breast cancer is not an "Indian" problem among health officials. Cancer statistics in general for American Indian and Alaska Natives are unreliable because of the frequency of racial misclassification, underreporting, and clustering data under the "other" category. Inclusive data from The Intercultural Cancer Council suggests that rates of breast cancer for American Indians and Alaska Natives, who experience the poorest 5-year survivorship, have been increasing over the past 20 years. The majority of the cancer research among Native people has concentrated on eliminating social, cultural, and structure barriers to healthcare. What has not been included in the literature are culturally-relevant psychosocial interventions incorporating the expressive arts. Behavioral research in cancer care for Native American women is needed to address quality of life factors. The purpose of this post modern narrative inquiry is to explore, through artmaking and storytelling, the belief systems surrounding wellness and physical illness from the perspective of Native women diagnosed with breast cancer. This narrative inquiry would provide the ground work for culturally-competent psychosocial interventions utilizing the expressive arts. Method. The participants were 2 American Indian women diagnosed with breast cancer from the Coharie tribe in Clinton, North Carolina, ages 74 and 66. These women were co-collaborators in an emergent narrative inquiry, incorporating a demographic interview, 3 main art task, and 8 open-ended interview questions. Their stories were analyzed discursively using the zoom model. To supplement the emergent themes from the analysis, 3 additional data sources, comprising interviews from a traditional healer and two tribal representatives, were included in the situational analysis. Results. Two positional "maps" were created from the layers of narrative and visual discourse analysis. The maps charted different positions along a four different continuums: cancer related medical treatment, traditional American Indian healing practices, wellness, and breast cancer and breast cancer treatment. The maps showed that wellness and spirituality were inseparable and a core belief to undergoing breast cancer treatment and survivorship. Traditional healing practices were viewed as a complementary approach to Western medicine; however, this approach was not a shared position with providers. The positional maps suggested that a more culturally-relevant, holistic, approach to cancer care was needed in this community.
  • ItemOpen Access
    Estrogen receptors alpha and beta: Opposing roles in hypothalamic-pituitary-adrenal axis function and stress-related behaviors
    (Colorado State University. Libraries, 2008) Weiser, Michael James, author; Handa, Robert, advisor
    Estradiol has reported effects on mood ranging from anxiogenic to anxiolytic and depressant to anti-depressant. These opposing actions of estradiol may be explained by the existence of two distinct estrogen receptor (ER) systems, ER alpha (ERα) and ER beta (ERβ). Furthermore, there exists a sex difference in stress-related psychiatric disorders such as anxiety and depression, for which women are more susceptible than men. Common to the pathology of these disorders is a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis where glucocorticoid negative feedback is impaired leading to chronically high levels of circulating glucocorticoids. The HPA axis is the main neuroendocrine axis that governs physiological responses to stressors. In rodents, basal and stress-induced activity of the HPA axis is higher in females than in males. This suggests that, if transferable to humans, the sex difference observed in HPA axis function in animal models may help explain the female predisposition for certain psychiatric disorders. The studies described in this dissertation were aimed at characterizing the distinct roles for ERα and ERβ in HPA axis activity and stress-related behaviors. The studies in Chapter 3 examine the effect of estradiol signaling through ERα or ERβ on glucocorticoid negative feedback of the HPA axis. Results indicate that estradiol impairs glucocorticoid-dependent negative feedback by activating ERα specifically at the level of the paraventricular nucleus (PVN). The studies in Chapter 4 examine the effect of estradiol signaling through ERα or ERβ on anxiety-like and depressive-like behaviors. Results indicate that selective activation of ERα is anxiogenic and depressant, whereas selective activation of ERβ is anxiolytic and antidepressant. Finally, the studies in Chapter 5 examine the effect of estradiol signaling through ERβ on behavior and HPA axis activity induced by glucocorticoid receptor (GR) activation in the central nucleus of the amygdala (CeA). Results indicate that delivery of a GR agonist to the CeA is anxiogenic and augments the HPA axis response to a stressor, and peripheral administration of an ERβ agonist blocks this effect. Collectively, these studies point to an antagonistic relationship between estradiol signaling through ERα and ERβ with respect to HPA axis activity and stress-related behaviors.
  • ItemOpen Access
    The process of designing and constructing an accessible residence hall for people with disabilities on a public university campus
    (Colorado State University. Libraries, 2008) Wernsman, M. Gayle, author; Lehmann, Jean P., advisor
    One of the great challenges to older universities and colleges is that of fashioning campuses that once disregarded and discouraged people with disabilities into welcoming and inclusive environments. Handicap accessibility can impact a university's recruitment of students, faculty and staff, building costs and budgets, the raising of public and private funding, and the marketability of the campus for events beyond academic uses, such as conventions, conferences, meetings and entertainment. This qualitative case study examined the process by which physical barrier removal and compliance with accessibility codes, such as the Americans with Disabilities Act, is accomplished on a public university campus and to identify the individuals who most influence these projects. The study was bounded by and limited to a newly constructed residence hall on the campus of Colorado State University. Methodology included three types of data gathering: interviews, site visit, and archival and documents search. The list of interview participants evolved in a chain or snowball sampling method. Data reduction was done by inductive analysis. What emerged is a story revealing the chronology of the funding, design and construction process of a residence hall. The apportionment and sequence of the responsibilities of each participant and their degree of influence on accessibility are discussed. Information gained from site visits and document findings was worked into this descriptive narrative. Themes that emerged were related to construction funding, bid proposals, accessibility issues and the experience and training of those interviewed. Also identified as themes were the construction of a full-scale model of a typical student room and the issue of why students with disabilities choose to live in an older dormitory. Findings are generalized into suggestions that administrators, architects, designers and facility planners can use to improve future university construction.