2015 UMKC Theses - Freely Available Online
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Item Expression Pattern of Drug-Resistance Genes in Candida Albicans at Different Fluconazole Concentrations(University of Missouri–Kansas City, 2015) Khanna, Aditi; White, Theodore C.Candida albicans is an opportunistic fungus that is part of the normal flora of our gastrointestinal and urinary tracts, but can cause infections in immune compromised individuals. Fluconazole (FLC), which is a fungistatic azole, is a common drug used for treatment of C. albicans infection by targeting lanosterol demethylase (ERG11). Some clinical isolates show resistance to FLC, which can be attributed to an over expression of ABC transporters (CDR1, CDR2), Major Facilitator Transporter (MDR1), and the azole target (ERG11). Commonly the expression pattern of these genes is compared across strains of susceptible and resistant strains in the absence of drugs. However, gene expression levels of each strain may be different in different drug doses. This study investigates the pattern of gene expression of MDR1, CDR1, CDR2, and ERG11 in different C. albicans matched isolates at different doses of FLC. Along with the wildtype strain SC5314, isolates from a single patient with varying susceptibility to FLC were selected. The Minimum Inhibitory Concentration (MIC80) to FLC for each strain was determined by microbroth dilution. The mRNA expression of the genes was analyzed using Quantitative Real-Time PCR (qRT-PCR) at FLC concentrations 4-fold lower, 4- fold higher, and at their respective MICs. Gene expression was analyzed with and without FLC induction and the MDR1/CDR1/CDR2/ERG11 gene expression levels of all the strains were normalized to their uninduced expression levels. The experiments show that in resistant strains, the genes MDR1 and ERG11 are over expressed even without FLC induction, consistent with previous work. Increasing the FLC concentration does not have any significant effect on gene expression in resistant strains. For the azolesusceptible strains, the gene expression of CDR1 and CDR2 increases at FLC concentration below its MIC80 and declines at concentrations above the MIC80. Hence, the gene expressions of clinical isolates vary according to their MIC80 values.Item Asymmetric Positron Annihilation in Chiral Tartrate and Tartaric Acid Crystals(University of Missouri–Kansas City, 2015) Corsiglia, Gerald A.; Van Horn, J. DavidPositron annihilation lifetime spectroscopy (PALS) has been used to study the interactions of positrons with chiral tartaric acids and tartrates. Differences in lifetimes of and its intensity I2 were compared between large crystals grown from the D- and L- enantiomers of sodium ammonium tartrate and tartaric acid. A tentative but statistical difference in and I2 between enantiomers is noted with the L- enantiomers exhibiting longer positronium lifetimes and lower intensities, signifying a more stable environment for the positron and positronium. Possible implications for the dominance of L-amino acids in living matter are discussed.Item Modeling and Design of a Silicon-Based High-Pressure 3HE Replacement Neutron Detector(University of Missouri–Kansas City, 2015) Rogers, Brent J.; Caruso, Anthony N.3He has stood as a major isotope used for neutron detection for many years. Due to national concerns of a possible 3He shortage, significant effort has been put forth, in the form of 3He alternative research, to push the community to develop more cost effective and higher intrinsic efficiency devices. The major focus of this thesis is on how a Si-based micro-structured neutron detector (MSND) assembly, of size and shape comparable to that of a commercially available high-pressure 3He-based neutron detector, can yield higher neutron detection efficiencies than its 3He-based counterpart. With careful consideration of MSND assembly geometry, along with clever utilization of neutron moderating high-density polyethylene (HDPE), a high-pressure 3He replacement (HP-HeRep) device, consisting of eighty tightly packed 1-cm2 MSND’s, has been designed and will be compared with a high-performance 8.3 absolute atmosphere 3He-based neutron detector. The MSND, designed and developed by the S.M.A.R.T. Lab at Kansas State University, is a high purity Si-based, highly anisotropic pin structure diode (i.e., 350-μm by 20-μm trenches in a 525-μm thick substrate). Given the novelty and complexity of the MSND, little is known in regard to its electric field character and resultant charge sweep-out properties. As a first step toward the development of a thorough understanding of these properties, this thesis also focuses on the equivalent circuit analysis and comparison of the MSND with a planar-type neutron detector, via impedance spectroscopy.Item Neutron Response Vectorization and Optimization of Moderating Neutron Spectrometers for Active Interrogation(University of Missouri–Kansas City, 2015) Myers, Eliot R.; Caruso, Anthony N.The detection of special nuclear material (SNM) is no trivial task; the low activity of isotopes such as 235U and the ease of shielding make their passive detection virtually impossible in the maritime environment. Active interrogation, while increasing the radiative signature, also increases the radiative background such that measuring SNM signatures becomes difficult, if not impossible, especially given an unknown and complex environment. Over the last two decades, numerous active interrogation methods and technologies have been proposed, many of which reduce or filter the relevant background by interrogating one type of radiation and measuring another type or property domain. However, by focusing on single properties of the SNM signature (e.g. time or energy) in laboratory conditions, the effectiveness of these methods in dynamic and unknown environments remains inadequate. In order for a method—or combination of methods—to be effective, it must be able to incorporate as much of the SNM signature as possible into the measurement, including the signature’s energy, time, and directional (or spatial) properties. The first part of this thesis provides a review of these methods and their limitations with an emphasis on outlining all of the SNM signature properties available to active interrogation applications. The second part discusses two improvements to multi-detector moderating neutron spectrometers in order to exploit all of these SNM signature parameters: time, energy, and space. The two new methods are: 1) an energy-specific optimization method for application driven spectrometer design via virtual detector simulations and genetic algorithms, and 2) a neutron response vectorization method for determining neutron source location by vectorizing the moderating neutron response functions. Although these new approaches by no means solve the problem of SNM detection, they provide a crucial step in tailoring moderating spectrometers to detecting the SNM signature, upon which future works can expand.Item Using WISE to Find Obscured AGN Activity in SDSS Mergers and Interactions(University of Missouri–Kansas City, 2015) Weston, Madalyn E.; McIntosh, Daniel H.In simulations, major encounters between gas-rich galaxies are predicted to drive gas to the centers of interacting and merging systems triggering new star formation (SF) and fueling an active galactic nucleus (AGN). Depending on the rate of SF, large amounts of obscuring dust can make detection of merger-induced activity difficult and may be at the heart of the ongoing merger-AGN connection debate. To provide better constraints on the importance of obscured AGNs, we use data from the Wide-field Infrared Survey Explorer (WISE) for a comprehensive sample of over 1000 major galaxy interactions and ongoing mergers visually selected from the SDSS with 1010 M and 0.01 < z < 0.08. We examine the [3.4]- [4.6] versus [4.6]-[12] color-color plane and find that most interactions and mergers have the same colors as “normal” (non-interacting and non-merging) galaxies, which define a narrow [3.4]-[4.6] locus and span a wide range in [4.6]-[12] colors from spectroscopically quiescent (blue, no warm dust) to galaxies with obscured SF. We find that 2 – 9 percent of mergers (and 1.0 – 2.5 percent of interactions) have unusually red [3.4]-[4.6] colors, which are associated with dust-obscured (Type-2) AGNs. Mergers (interactions) are 5 – 18 (3 – 5) times more likely to host a buried AGN than normal galaxies. This increased likelihood of dusty AGN activity in mergers and interactions supports an AGN-merger connection. We investigate the nature of merging and interacting galaxies with dusty AGN. We find that dusty AGN mergers and interactions favor smaller pair separations, smaller dark matter halo masses, and higher [OIII] luminosities (a proxy for AGN power) than the bulk of mergers and interactions with normal WISE colors. Using SDSS urz colors to distinguish quiescent from star-forming galaxies, we find that more than three-quarters of the WISE AGN subpopulation of mergers and interactions are forming stars. We find that AGNs also classified as ongoing mergers are 2 – 6 times more likely to be obscured than AGNs in nonmerging, non-interacting galaxies. Around half of merging AGNs are obscured, suggesting that shorter wavelengths will be inadequate in selecting AGNs in merging systems. We find no association between merging systems and optically identified AGNs (Seyferts), suggesting that central star formation (and thus dust obscuration) is the key to making an AGN in a merger. Our findings indicate a strong association between ongoing star formation and dust-enshrouded black hole growth in merging galaxies as predicted in the modern merger hypothesis.