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Title: PRFA-LIKE TRANSCRIPTION FACTOR, LMO0753, CONTRIBUTES TO VIRULENCE, L-RHAMNOSE UTILIZATION, AND PERSISTENCE OF LISTERIA MONOCYTOGENES HUMAN FOODBORNE OUTBREAK LINEAGES
Creator: Salazar, Joelle Krieger
Date: 2013, 2013-12
Description: Listeria monocytogenes is a foodborne bacterial pathogen and the causative agent of a human and animal disease, listeriosis. Among the three...
Show moreListeria monocytogenes is a foodborne bacterial pathogen and the causative agent of a human and animal disease, listeriosis. Among the three major genetic lineages of L. monocytogenes (i.e. LI, LII, and LIII), LI and LII are predominantly associated with foodborne listeriosis outbreaks, whereas LIII is rarely implicated in human infections. In a previous study, we identified a Crp/Fnr family transcription factor lmo0753 that was highly specific to outbreak-associated LI and LII but absent from LIII. Lmo0753 shares two conserved functional domains including a DNA-binding domain with the well-characterized master virulence regulator PrfA in L. monocytogenes. In this study, lmo0753 deletion and complementation mutants were constructed in two fully sequenced L. monocytogenes LII strains 10403S and EGDe, and compared virulence-associated mechanisms of flagellar motility, phospholipase C production, hemolysis, and intracellular growth of the mutants and their respective wild types. Persistence-associated mechanisms of growth, biofilm production, attachment and soil survival were also assayed. Results suggested that lmo0753 plays a role in some virulence- and persistence-associated mechanisms in both EGDe and 10403S. More importantly, it was found that deletion of lmo0753 led to the loss of L-rhamnose utilization in EGDe but not in 10403S. Transcriptomic comparison of the EGDe lmo0753 deletion mutant and the wild type incubated in Phenol-red medium containing L-rhamnose as the sole carbon source revealed 126 (4.5%) and 546 (19.5%) out of 2,798 genes in the EGDe genome that were up- and down-regulated for more than 2-fold, respectively. Genes involved in biotin biosynthesis, general stress response and rhamnose metabolism were shown to be differentially regulated by Lmo0753. Findings from this study may partially explain why xvi LIII of L. monocytogenes is underrepresented in the environment and rarely associated with human listeriosis outbreaks due to the inability of rhamnose utilization.
PH.D in Biology, December 2013
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Title: BAX EXON 2 CONTAINS A CRITICAL ACCEPTOR SITE FOR ALTERNATIVE SPLICING OF THE BAXΔ2 ISOFORM BY SAMUEL KISSINGER Submitted in partial fulfillment of the requirements for
Creator: Kissinger, Samuel
Date: 2013-04-17, 2013-05
Description: Previous studies have revealed that BAXΔ2, an alternatively spliced form of BAX with a microsatellite mutation (G8 to G7) on BAX exon 3, is a...
Show morePrevious studies have revealed that BAXΔ2, an alternatively spliced form of BAX with a microsatellite mutation (G8 to G7) on BAX exon 3, is a more potent inducer of cell death and a potential means of treatment for cancers with microsatellite instability (MSI). To define the critical splicing points for the splicing of the BAXΔ2 isoform, BAX mini-gene constructs with GFP reporter genes were used for site directed mutagenesis based disruption of predicted critical splicing points. The mutant constructs were transfected into mammalian cells, and expression of BAX-GFP fusion proteins were examined by both fluorescence microscopy and Western blot analysis. Our results indicate that the BAX exon 2 A667T mutation could completely abolish generation of the BAXΔ2 isoform. These results suggest that the acceptor site AG in BAX exon 2 position 667 is critical for alternative splicing to the BAXΔ2 isoform in microsatellite unstable BAX G7 tumor cells.
M.S. in Biology, May 2013
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Title: PROFESSIONAL AND TECHNICAL COMMUNICATIONS CONTRIBUTIONS TO STUDENT AFFAIRS WRITING COMPETENCIES
Creator: Schaefer, Kelly
Date: 2016, 2016-05
Description: Student affairs practitioners in mid-level positions write in the workplace daily, but in many cases they do not formally or intentionally...
Show moreStudent affairs practitioners in mid-level positions write in the workplace daily, but in many cases they do not formally or intentionally train themselves or their staff members to write. I used qualitative methods of semi-structured interviews, observations, and document analysis to investigate how and to what extent mid-level managers are competent writers. And in terms of their organizations, I investigated the value placed on writing and how and to what extent writing training happens. The investigation of writing practices of professionals working in campus centers in the field of student affairs shows that mid-level campus center professionals write extensively in their positions, including writing across many document types (letters, memos, reports, financial documents), and for multiple audiences in and outside of the university setting (students, staff, peers, supervisors, community members, alumni). Mid-level managers value writing ability and the ability of their staff members to be able to write, and could improve writing knowledge and ability through competency training and development by connecting with work in the field of professional communication. Professional associations can and should support professionals using competency language that supports writing and writing training to develop writing skill and ability competencies. Mid-level managers, as both writers and supervisors, could join associations in employing intentional strategies for writing and writing training suggested by professional communication research.
Ph.D. in Technical Communication, May 2016
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Title: SEISMIC STUDY OF HYBRID SHEAR WALL SYSTEM
Creator: Xu, Lifeng
Date: 2013, 2013-07
Description: This thesis represents the seismic behavior of new hybrid shear wall system, which consists of two exterior precast wall layers and one...
Show moreThis thesis represents the seismic behavior of new hybrid shear wall system, which consists of two exterior precast wall layers and one interior cast-in-place concrete layer. The “sandwich” shaped shear walls were already tested as a full scale specimen subjecting to vertical pressure and cyclic horizontal load in Anhui University of Architecture, China (2010). A series of 3D non-linear finite element models which include all significant details and specifications were then created in ABAQUS to simulate the experiments. The pushover analyses method was employed to reproduce the test procedures. The response of the structure was computed both at macro and micro level at the result in order to validate the correctness of the analytical model. After verifying the good agreement between the experimental observations and simulation results, an extended parametric study was conducted towards this hybrid shear wall system to explore its damage mechanism and design optimization. Based on hybrid shear wall's specific seismic resisting capacity which derived from the previous simulation, a series of 2D models were created in SAP2000 to evaluate the seismic performance of hybrid shear wall structure. What's more, in order to precisely represent the 3D model effect into 2D model in SAP2000,3D model was created in ABAQUS to account for the influence of semi-rigid connection between the concrete diaphragm and hybrid shear wall. After applying the ability of semi-rigid connection and hybrid shear wall, pushover method and time history analysis were conducted towards this 18 story structure model. The global seismic performance factor is finally evaluated according to the FEMA-P695.
PH.D in Civil Engineering, July 2013
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Title: REMOVAL OF BACTERIAL CONTAMINANT FROM MODEL SUBSTRATES USING A MICELLAR NANOFLUID FORMULATION
Creator: Shim, Jiyoung
Date: 2017, 2017-05
Description: The oscillatory structural force (OSF) of a micellar film of sodium dodecyl sulfate (SDS) was monitored with atomic force microscope (AFM)...
Show moreThe oscillatory structural force (OSF) of a micellar film of sodium dodecyl sulfate (SDS) was monitored with atomic force microscope (AFM) using an attached glass microsphere against a smooth flat and energy homogenous solid substrate. The force versus distance measurements for the 0.03M and 0.06 M SDS micellar solutions were monitored. The force versus distance had an oscillatory decay profile with a period of oscillation which was the same as the micellar diameter. The number of periodic oscillations increased with an increase in the micellar concentration. The OSF in the SDS micellar film confinement was also proved by a thinning single foam film formed from a micellar solution. It was observed that, due to micellar layering, the film thinned in a multiple regular stepwise manner promoted by the OSF. The results obtained by the AFM and thinning single foam film were used in the application of the OSF to remove bacteria from a model solid substrate. The experimental data for the OSF was complemented with modeling research. The theoretical OSF curves were obtained using the statistical mechanics approach. The experimental data and theoretical results for OSF for SDS micellar film were analyzed and found to be in fair agreement with each other. Based on the model prediction calculation, the structural film interaction energy barrier for the both the 0.03 M and 0.06 M SDS micellar solutions was calculated; the estimated structural film interaction energy barrier due to the presence of the OSF was about 10 3 kT / 􀝉􀬶 for the 0.03 M SDS micellar solution and about 5 x 10􀬷 kT /􀝉􀬶for the 0.06 M SDS micellar solution in film with micellar layers at about 25 ºC. Understanding the interactions between bacteria and solid surfaces that result in bacterial adsorption and removal is of immense importance for reducing foodborne illness outbreaks. Here, we used fluorescence microscope in conjunction with the concept of the diffusion of bacteria from the bulk suspension to the substrate and the adsorption isotherm to estimate the adsorption energy for E.coli K12; we obtained a value of about 2.5 kT. This value compares favorably with the value of 2.1 kT reported previously for E.coli NCTC 9002 [49]. We also used the dynamic light scattering method to estimate the radius of gyration of E.coli K12, which has a diameter of about 1 m and a length of 2 m to estimate the effective volume. The radius of gyration was also used to estimate the surface area covered by the bacterium and compared it to the surface area measured from the image taken with fluorescence microscope. A nanofluid formulation comprised of a sodium dodecyl sulfate (SDS) micellar aqueous solution in the presence of an organic acid (as a pH controller) was used to test the E. coli K12 removal from two substrates, polyvinylchloride (PVC) and partially hydrophobic glass. We investigated the bacterial removal efficacy based on the combined effect of the nanofluid’s structural forces and bacterial isoelectric point. We predicted the nanofilm oscillatory structural energy (NOSF) against the E.coli K12 adsorption energy by applying the statistical mechanics approach. Based on the model prediction, the NOSF was estimated at the vertex of three phase contact angle between a bacterium and the substrate (i.e., the wedge film’s interaction energy at one particle layer). The evaluated film’s repulsive energy due to the NOSF was about 15.6  4.4 kT of the 0.02 M SMNF (the SDS micellar nanofluid formulation) and several times higher than the bacterial adsorption energy, 2.5  0.2 kT. These findings suggest that the NOSF is capable of bacteria/microorganism removal from contaminated substrates. Here, we present a methodology based on NOSF to optimize the nanofluid formulation for bacterial substrate removal and bulk inactivation. The results of this study will assist the food industry with the design of proper sanitation and will enhance microbial removal and inactivation strategies.
Ph.D. in Chemical Engineering, May 2017
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Title: EXPERIMENTAL METHODS TO DETERMINE MECHANICAL PROPERTIES OF ALUMINUM FOAM LIGAMENTS
Creator: Mathur, Saurabh
Date: 2013, 2013-07
Description: Metal foams are widely used these days and their applications are far reaching from engineering to medical and beyond. This study is aimed at...
Show moreMetal foams are widely used these days and their applications are far reaching from engineering to medical and beyond. This study is aimed at characterizing the property of aluminum foam ligaments in terms of their strength and response to loads. The defining characteristic of metal foams is a very high porosity: typically 75– 95% of the volume consists of void spaces which give them high strength to weight ratio. The aluminum foam (Duocell by ERG Aerospace Corp.) that is used in this study is manufactured using the parent material aluminum alloy 6101-T6. Through this work an effort has been made to understand the mechanical properties of aluminum foam ligaments. The elastic modulus was estimated by conducting bending experiments on ligaments. The yield stress was estimated through both bending and tension experiments which are followed by estimation of ultimate tensile stress using tension experiments on ligaments. A comparative study was also done to understand the difference in mechanical properties of ligaments to that of bulk aluminum alloy 6101-T6. This work also laid emphasis on characterization of ligament geometry in order to understand the mechanical properties of material as geometry plays a very crucial role in the mechanical response of ligaments. The elastic modulus of ligaments was estimated as 13.3 GPa. The yield strength from tension experiment was estimated as 140 MPa and the ultimate tensile strength was estimated as 190MPa
M.S. in Mechanical and Aerospace Engineering, July 2013
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Title: SYNTHESIS AND INVESTIGATION OF NOVEL CATHODE MATERIALS FOR SODIUM ION BATTERIES
Creator: Sawicki, Monica
Date: 2015, 2015-12
Description: Environmental pollution and eventual depletion of fossil fuels and lithium has increased the need for research towards alternative electrical...
Show moreEnvironmental pollution and eventual depletion of fossil fuels and lithium has increased the need for research towards alternative electrical energy storage systems. In this context, research in sodium ion batteries (NIBs) has become more prevalent since the price in lithium has increased due to its demand and reserve location. Sodium is an abundant resource that is low cost, and safe; plus its chemical properties are similar to that of Li which makes the transition into using Na chemistry for ion battery systems feasible. In this study, we report the effects of processing conditions on the electrochemical properties of Na-ion batteries made of the NaCrO2 cathode. NaCrO2 is synthesized via solid state reactions. The as-synthesized powder is then subjected to high-energy ball milling under different conditions which reduces particle size drastically and causes significant degradation of the specific capacity for NaCrO2. X-ray diffraction reveals that the lattice distortion has taken place during high-energy ball milling and in turn affects the electrochemical performance of the cathode material. This study shows that a balance between reducing particle size and maintaining the layered structure is essential to obtain high specific capacity for the NaCrO2 cathode. In light of the requirements for grid scale energy storage: ultra-long cycle life (>20,000 cycles and calendar life of 15 to 20 years), high round trip efficiency (> 90%), low cost, sufficient power capability, and safety; the need for a suitable cathode materials with excellent capacity retention such as Na2MnFe(CN)6 and K2MnFe(CN)6 will be investigated. Prussian blue (A[FeIIIFeII (CN)6]•xH2O, A=Na+ or K+) and its analogues have been investigated as an alkali ion host for use as a cathode material. Their structure (FCC) provides large ionic channels along the <100> direction enabling facile insertion and extraction of alkali ions. This material is also capable of more than one Na ion insertion per unit formula which holds great promise in increasing the energy density of the NIB. The electrochemical performance of the cathode material will be analyzed using cyclic voltammetry, and galvanostatic charge/discharge investigation.
Ph.D. in Materials Science and Engineering, December 2015
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Title: KINETIC STUDY OF BOTRYOCOCCUS BRAUNII AND BACTERIAL STRAIN MASS PRODUCTION
Creator: Ghodsi, Seyed Mohammadreza
Date: 2014, 2014-07
Description: The increase on petroleum-based fuel demand, lack of sufficient petroleum resources, reaching hazardous limits of green house gases and the...
Show moreThe increase on petroleum-based fuel demand, lack of sufficient petroleum resources, reaching hazardous limits of green house gases and the need for energy security are motivating the development of an alternate fuel besides conventional gas. Bio-diesel, as a potential replacement to petrol, is technically feasible, environmentally friendly, produced locally and provides low gallon per Btu. Biodiesel obtained from microalgae is a form of fuel being used recently which gives the opportunity to obtain energy in environmental friendly and sustainable manner without competing on human’s food as biofuel feedstock; growing microalgae and turning it to biodiesel is not cost effecttive yet though. In order to minimize the cost of microalgae production, each step of algal growth should be studied and optimized. The separation of algae cells from their aquatic medium, known as harvesting, is the most challenging and energy consuming step of growth cycle. Different studies have shown more than 30% of algal production energy consumption is dedicated to the harvesting phase. Small size of algae cells, low concentration, small density difference between algae and medium and ionic charge of medium makes it impossible to sediment algae cells by gravity or coagulation. An effective method to separate algae from its medium could be bio-flocculation. In this research Botryococcus Braunii microalgae has been co-cultured with a bacterial flocculant to form clumps of easy-harvesting biomass. The growth kinetics of this novel feedstock has been studied for the very first time, based on literature, and its optimum growth conditions have been derived.
M.S. in Chemical Engineering, July 2014
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Title: HIGH ENERGY SODIUM BASED ROOM TEMPERATURE FLOW BATTERIES
Creator: Shamie, Jack
Date: 2015, 2015-12
Description: As novel energy sources such as solar, wind and tidal energies are explored it becomes necessary to build energy storage facilities to load...
Show moreAs novel energy sources such as solar, wind and tidal energies are explored it becomes necessary to build energy storage facilities to load level the intermittent nature of these energy sources. Energy storage is achieved by converting electrical energy into another form of energy. Batteries have many properties that are attractive for energy storage including high energy and power. Among many di erent types of batteries, redox ow batteries (RFBs) o er many advantages. Unlike conventional batteries, RFBs store energy in a liquid medium rather than solid active materials. This method of storage allows for the separation of energy and power unlike conventional batteries. Additionally ow batteries may have long lifetimes because there is no expansion or contraction of electrodes. A major disadvantage of RFBs is its lower energy density when compared to traditional batteries. In this Thesis, a novel hybrid Na-based redox ow battery (HNFB) is explored, which utilizes a room temperature molten sodium based anode, a sodium ion conducting solid electrolyte and liquid catholytes. The sodium electrode leads to high voltages and energy and allows for the possibility of multi-electron transfer per molecule. Vanadium acetylacetonate (acac) and TEMPO have been investigated for their use as catholytes. In the vanadium system, 2 electrons transfers per vanadium atom were found leading to a doubling of capacity. In addition, degradation of the charged state was found to be reversible within the voltage range of the cell. Contamination by water leads to the formation of vanadyl acetylacetonate. Although it is believed that vanadyl complex need to be taken to low voltages to be reduced back to vanadium acac, a new mechanism is shown that begins at higher voltages (2.1V). Vanadyl complexes react with excess ligand and protons to reform the vanadium complex. During this reaction, water is reformed leading to the continuous cycle in which vanadyl is formed and then reduced back to the original state. In the discharged state, it was found that precipitation occurs, but is due to solubility limits and not chemical reactions. The TEMPO system showed the potential of higher concentration catholytes although large capacity losses were found. Although no explanation is found, the behavior of the fade is related to time and concentration.
Ph.D. in Mechanical, Materials and Aerospace Engineering, December 2015
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Title: Serostatus Disclosure as a Predictor of Metal Health and Physical Health Among HIV-Seropositive Adults
Creator: Niel, Kristin
Date: 2011-05-09, 2011-05
Description: As estimated 1,200,000 people in the United States were living with HIV in 2009 (UNAIDS, 2010). African Americans have an incidence rate seven...
Show moreAs estimated 1,200,000 people in the United States were living with HIV in 2009 (UNAIDS, 2010). African Americans have an incidence rate seven times that of Caucasians. Research has shown that HIV-positive people have high levels of psychological distress (Cook et al., 2006); depression is the most frequently diagnosed disorder (Treisman, Angelino, & Hutton, 2001). Distress negatively impacts physical health (Comer, Henker, Kemeny, & Wyatt, 2000; Cruess et al., 2005) and medication adherence (Cook, et al., 2006; Mellins et al., 2002) in HIV-positive patients. Although disclosure of HIV-seropositivity can lead to increased social support (Armistead, Morse, Forehand, Morse, & Clark, 1999), it may also lead to social rejection, prejudice and increased distress (Cederfjall, Langius-Eklof, Lidman, & Wredling, 2001; Kalichman, DiMarco, Austin, Luke, & DiFonzo, 2003). This study examined 110 HIV-positive patients at an urban medical clinic. Patients completed self-report measures as part of a larger study investigating posttraumatic growth in HIV/AIDS. It was hypothesized that (a) more participants would disclose to friends and partners than to family; (b) participants who disclosed to more people would endorse fewer symptoms of distress; and (c) participants who disclosed to fewer people would be less likely to adhere to medical regimens and routinely attend medical appointments, and have poorer health outcomes. Distress was measured by Psychiatric Symptom Index (PSI), Beck Depression Inventory (BDI), and the Impact of Event Scale (IES). Viral load and CD4 cell counts were found in medical charts, and the AIDS Clinical Trails Group Adherence Follow-up Questionnaire measured adherence. Analyses reveal that 67.3% of participants disclosed to family, 55.5% to at least one partner, and 45.5% to friends. A negative association existed between full disclosure and IES Avoidance scale (r = -.20, p< .05). There were positive associations between disclosure to family and the PSI Depression Scale (r = .22, p < .05), Cognitive Disturbance Scale (r = .21, p < .05), and PSI Total Score (r = .22, p < .05), implying that disclosure to more groups of people may be associated with increases in psychological distress ratings. Implications of these findings are discussed.
M.S. in Psychology, May 2011
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Title: A THERMAL RESISTANCE STUDY OF SHIGA TOXIN-PRODUCING ESCHERICHIA COLI (STEC) IN LOW MOISTURE FOOD WITH THE USE OF A DIFFERENTIAL SCANNING CALORIMETER (DSC)
Creator: Liu, Shi
Date: 2014, 2014-12
Description: According to CDC's Foodborne Disease Outbreak Surveillance System database, from the years 2007-2011, there were eight outbreaks associated...
Show moreAccording to CDC's Foodborne Disease Outbreak Surveillance System database, from the years 2007-2011, there were eight outbreaks associated with low-moisture food including nuts, cheese, cookie dough, and wheat snack food involving Shiga toxinproducing Escherichia coli O157:H7 (STEC), which led to over 318 cases of foodborne illnesses. Yet, insufficient data on STEC thermal inactivation has been obtained in lowmoisture food. In this study, a novel methodology using a Differential Scanning Calorimeter was used to measure STEC thermal inactivation kinetics in low moisture environments. The objective of this study was to use a Differential Scanning Calorimeter to measure D- and z-values, and therefore to determine the microbial thermal resistance, of select STEC strains. Five strains of outbreak related E. coli O157:H7 and one strain of E. coli K12 were individually grown on tryptic soy agar with 0.6% yeast extract (TSAYE). The cells were harvested and inoculated into sample matrices. Matrices included a moist buffered peptone water solution, a simple model low-moisture food matrix (corn syrup), and lowmoisture food (oat flour and peanut butter). Samples were individually heated using a Differential Scanning Calorimeter (DSC). The DSC was able to achieve a reproducible and accurate thermal environment. Following heat treatment, microbial survivors were enumerated via a traditional plate counting method. The six strains showed greater thermal resistance in corn syrup than in a buffered solution and in peanut butter and oat flour compared with both the corn syrup or buffer solution (p < 0.05). At the same processing condition linearly rising temperature at 5oC/min, in low moisture food matrices, approximately 90oC and 95oC was needed to reduce the outbreak strains of STEC in peanut butter and oat flour by 5-log CFU/g; whereas 85oC and 75oC were needed for corn syrup and buffer solution, respectively. D65 o C ranged from 0.26-0.92 min for all strains tested in buffer. Those same strains exhibited a 10-100 times increase in resistance in corn syrup (D65 o C = 2.6-108.6 min). The measurement that quantifies the increased heat resistance of STEC in low moisture food will improve science-based risk reduction by ensuring process lethality in these types of food.
M.S. in Food Safety and Technology, December 2014
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Title: ENRICHMENT OF COXIELLA BURNETII FROM BOVINE AND NON-BOVINE MILKS USING AN AXENIC LIQUID CULTURE MEDIUM
Creator: Shi, Manman
Date: 2016, 2016-07
Description: Non-bovine milks are becoming more popular as beverages and for making cheeses, however little are understood regarding how pathogens are...
Show moreNon-bovine milks are becoming more popular as beverages and for making cheeses, however little are understood regarding how pathogens are inactivated in these milks during pasteurization. Recently, a tissue culture-PCR method has been developed to quantify inactivation of Coxiella burnetii, the obligate intracellular bacterium which is the reference pathogen for milk pasteurization. Unfortunately, this method is time-consuming and quite laborious. A potential improvement over the ICC-PCR method may be the use of a new specialized liquid medium which has been shown to allow growth of pure cultures of C. burnetii outside of host cells. In this study, ACCM-2 was evaluated for its’ ability to enrich C. burnetii from bovine and non-bovine milks as a potential alternative to tissue culture enrichment for Most Probably Number (MPN) quantification of inactivation of C. burnetii in milks. C. burnetii in bovine whole milk and cream (as a surrogate for a high fat product), camel, water buffalo, and goat milk were grown in ACCM-2 media (1:10) in 10 mL volumes in T-25 flasks at 37 °C under 5% CO2 and 2.5% O2 with sampling over 14 days. C. burnetii levels were determined by quantitative PCR (qPCR) against a standard curve for the Coxiella-specific IS1111a gene. C. burnetii in all milks grew at least 3 logs over 10 days with the exception of the water buffalo milk which did not allow growth. Bovine milk allowed the least growth and additional studies determined that the detection limit for growth of C. burnetii from this milk is about 6 ge/mL. Additional studies showed that adjustment of the pH from ~5.0 to 4.75 results in much improved growth of C. burnetii from bovine milk. Adjustment of pH did not allow growth from water buffalo milk, however additional dilution of the milk did allow improved C. burnetii growth but the added dilution also decreases the detection limit of the proposed new MPN-PCR assay. Further studies were completed to determine how thermal injury affects recover and growth of Coxiella burnetii in ACCM-2 media after thermal processing at 64 °C for up to 8 minutes. Although injury did increase the lag phase period and reduce the log phase growth rate from these samples, recovery and growth of at least 0.5 log was possible from all samples indicating that this media should be useful as an alternative enrichment method for use in an MPN format for quantification of thermal inactivation of C. burnetii in both bovine and non-bovine milks.
M.S. in Food Safety and Technology, July 2016
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Title: WIRELESS LINK SCHEDULING UNDER PHYSICAL INTERFERENCE MODEL
Creator: Ma, Chao
Date: 2014, 2014-07
Description: Latency minimization and capacity maximization are fundamental combinatorial optimization problems in wireless networks. Given a set of...
Show moreLatency minimization and capacity maximization are fundamental combinatorial optimization problems in wireless networks. Given a set of communication links in a multihop wireless network, the former computes a schedule satisfying all link demands with shortest latency, while the latter aims at selecting a maximum feasible subset of these links. We study both the Shortest Link Schedule (SLS) and Maximum Independent Set of Links (MISL) from a theoretical perspective, striving for generalized algorithmic treatments and provable approximation guarantees. Wireless devices are prone to radio frequency interference emanating from other devices. Interference can be major inhibitor to transmission performance, degrading the signal quality or even causing the communication to fail. Several models have been used for modeling wireless interference over the past decades. In contrast to graph-based protocol models, which assume the interference end at some boundary, we consider a more realistic SINR-based physical interference model. Under physical interference model, the problem SLS and MISL are hard to solve due to the technical obstacles caused by the ambient noise, non-local and additive nature of interference. In this dissertation, we consider both fixed transmission powers and power control. We explore interference natures under physical interference model and propose a generalization of independent set, which is capable of modeling the independent sets of wireless links. In addition, we present constant-approximation algorithm for MISL with monotone and sub-linear power assignment in both unidirectional and bidirectional mode, and for MISL with sub-mean power assignment in bidirectional mode. We also present constant-approximation algorithm for Maximum Weighted Independent Set of Links (MWISL) with linear power assignment in both unidirectional and bidirectional mode. For MISL with power control in unidirectional mode, we develop a constant-approximation algorithm with the canonical iterative power assignment.
Ph.D. in Computer Science, July 2014
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Title: SYSTEMATIC CONSTRUCTION OF SALMONELLA ENTERITIDIS-SPECIFIC GENE DELETION MUTATIONS
Creator: Li, Ye
Date: 2013, 2013-12
Description: Salmonella enterica serovar Enteritidis infection is one of the major foodborne illnesses associated with egg, cattle and poultry products....
Show moreSalmonella enterica serovar Enteritidis infection is one of the major foodborne illnesses associated with egg, cattle and poultry products. Genes which are specific to S. Enteritidis may play an important functional role in the pathogens’ ability to survive and persist in these food products, and thus cause human foodborne outbreaks. Acquiring more knowledge on how this bacterium is capable of survival will aid in developing strategies to minimize its existence in the Nation’s food supply. In this study, we constructed S. Enteritidis-specific gene deletion mutants for use in subsequent functional studies. Out of more than 200 S. Enteritidis specific genes, 46 genes were selected for deletion in S. Enteritidis PT4. These 46 genes were selected because they are absent in both S. Typhimurium and S. Typhi based on percent identity scores retrieved from standalone BLAST software analysis. The deletion mutants were constructed using the lambda red recombinase method and a PCR product containing unique barcodes. This library of uniquely barcoded mutants will be useful in determining survival and persistence of this organism both in nature and in vivo.
M.S. in Food Safety and Technology, December 2013
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Title: HIGH PERFORMANCE LOGIC DESIGN FOR ADAPTIVE FIR FETAL ECG ESTIMATION
Creator: Wang, Sizhou
Date: 2014, 2014-05
Description: This thesis presents realizations of IEEE-754 single precision floating point non-invasive fetal ECG estimation based on QR Decomposition...
Show moreThis thesis presents realizations of IEEE-754 single precision floating point non-invasive fetal ECG estimation based on QR Decomposition Recursive Least Square algorithm (QRD-RLS). Experiments of the system, which is implemented on Xilinx Zynq SoC platform, are carried out with electrocardiogram (ECG) data and the results with analysis are presented. The embedded system design aims for saving resources, streaming pipeline performance and software-aid computation and integration. The challenge of exploiting the system full potential with pseudo-parallel computation on multiple fetal ECG data packets is also examined.
M.S. in Computer and Electrical Engineering, May 2014
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Title: MESOSCALE DEFORMATION IN A 9310 STEEL AND 2139 ALUMINUM ALLOY
Creator: Snyder, David
Date: 2012-09-10, 2012-12
Description: As technology continues to develop, the need for materials with superior structural performance grows. In recent years, the design of such...
Show moreAs technology continues to develop, the need for materials with superior structural performance grows. In recent years, the design of such high integrity alloys has led to a need for a more fundamental understanding of the deformation response of materials under various loading conditions. In this study, the deformation response of two high performance, high stacking fault metallic alloys are investigated. It has long been known that deformation in high stacking fault metals is a complex process of dislocation interactions that vary substantially with the loading conditions of strain, strain rate and temperature, as well as the chemistry and processing history of the alloy. The flow behavior and recrystallization response of a 9310 steel alloy deformed in the ferrite temperature range were studied in this work. Samples were compressed under various conditions of strain, strain rate and temperature using a Gleeble thermo-mechanical simulator. Deformation was characterized by both qualitative and quantitative means, using standard microscopy, electron backscatter diffraction (EBSD) analysis and flow stress modeling. The results indicate that deformation is primarily accommodated through dynamic recovery in sub-grain formation. EBSD analysis shows a continuous increase in sub-grain boundary misorientation with increasing strain, ultimately producing recrystallized grains from the sub-grains at high strains. This suggests that a sub-grain rotation recrystallization mechanism predominates in this temperature range. Demonstrated trends include a decreasing mean dynamically recrystallized grain size with increasing strain and Zener-Hollomon parameter, and an increasing recrystallized fraction with increasing strain. Another high stacking fault metal that has garnered a great deal of attention for its possible high performance structural applications is the 2139 aluminum alloy. In this study, the effect of chemistry and strain on the deformation response of the alloy system is investigated. 2139 aluminum is a very complex alloy, with multiple strengthening phases and mechanisms contributing to its overall high structural integrity compared to other aluminum alloys in its class. While the structural performance and TEM-scale deformation behavior of this alloy have been extensively analyzed, grain-scale microstructural features of deformation have not been well characterized. In addition, the contributions of each strengthening mechanism in the alloy are not well established. To characterize the deformation response of the alloy, alloys of various chemistries were produced and subjected to room temperature compression testing, in order to isolate and establish the effects of the major strengthening mechanisms on the overall behavior. Through electron backscatter diffraction analysis, the microstructural features of deformation generated in the alloys under these conditions were characterized, and the evolution and distribution of strain on a grain-scale was analyzed. Differences in deformation behavior with alloy chemistry were established by tracking differences in the evolution of lattice rotations with strain in the several alloys. It was determined that, for alloys subjected to artificial aging, the refinement in scale and distribution of the precipitate structure represents the greatest decrease in the development of lattice rotations with strain. This represents a first study into the room temperature, grain-scale deformation response of a heavily alloyed aluminum alloy, and the effect of alloy chemistry and precipitate structure on the deformation behavior of a 2139 aluminum alloy. As a preface to this study, a thorough review of the current state of literature on the deformation response of aluminum alloys was compiled as well.
M.S. in Materials Science and Engineering, December 2012
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Title: STUDIES IN NONEQUILIBRIUM STATISTICAL MECHANICS
Creator: Wang, Huichao
Date: 2013-05-08, 2013-05
Description: This thesis gives a brief outline of how the microscopic representation enters into a good description of the elasticity of a fluid. We first...
Show moreThis thesis gives a brief outline of how the microscopic representation enters into a good description of the elasticity of a fluid. We first introduce the hydrodynamics by three continuity equations. Due to its macroscopic background, we point out its limitation that it does not fit well with the elastic behavior of the fluid. Therefore we introduce the microscopic description of the system. In order to connect the elasticity which is obviously involved in the non-equilibrium state of a fluid, we discuss how non-equilibrium mechanics could be related to equilibrium mechanics by the assumption that the system is not far away from equilibrium. Under this assumption, an analysis of equilibrium mechanics is necessary, and combining with the microscopic representation, we derive the generalized Langevin equation as an equation of motion of the momentum current, which is endowed with the elastic property, consistent with observations of the fluid.
M.S. in in Physics, May 2013
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Title: SYSTEM-ON-CHIP ARCHITECTURES FOR SIGNAL PROCESSING AND COMMUNICAnONS
Creator: Niu, Sufeng
Date: 2012-04-30, 2012-05
Description: System-On-Chip (SOC) is one of the most popular Computer Aided Design (CAD) methodologies in electronic system design. In this research, SOC...
Show moreSystem-On-Chip (SOC) is one of the most popular Computer Aided Design (CAD) methodologies in electronic system design. In this research, SOC design is investigated in two different types of applications: i) low cost and power efficient applications; and ii) high performance computing applications. To explore low cost and power efficient design, a microcontroller based wireless medical system is investigated. Two wireless communication protocols for medical applications and patient monitoring are analyzed. In addition, the ZigBee stack developed by TI and a medical amplifier are discussed. For high performance SOC applications, implementations of several matrix operations are examined. An improved fixed-point hardware design of QR decomposition is introduced and optimized for Xilinx FPGAs. A Givens Rotation algorithm is implemented using a folded systolic array and the CORDIC algorithm. This approach is highly suitable for high-speed FPGAs or ASIC designs. It is found that the Xilinx XC5VLX110T FPGA is capable of running the QR decomposition at 246MHz.
M.S. in Electrical Engineering, May 2012
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Title: Improving Localization Safety for Landmark-Based LiDAR Localization System
Creator: Chen, Yihe
Date: 2024
Description: Autonomous ground robots have gained traction in various commercial applications, with established safety protocols covering subsystem...
Show moreAutonomous ground robots have gained traction in various commercial applications, with established safety protocols covering subsystem reliability, control algorithm stability, path planning, and localization. This thesis specifically delves into the localizer, a critical component responsible for determining the vehicle’s state (e.g., position and orientation), assessing compliance with localization safety requirements, and proposing methods for enhancing localization safety.Within the robotics domain, diverse localizers are utilized, such as scan-matching techniques like normal distribution transformations (NDT), the iterative closest point (ICP) algorithm,probabilistic maps method, and semantic map-based localization.Notably, NDT stands out as a widely adopted standalone laser localization method, prevalent in autonomous driving software such as Autoware and Apollo platforms.In addition to the mentioned localizers, common state estimators include variants of Kalman Filter, particle filter-based, and factor graph-based estimators. The evaluation of localization performance typically involves quantifying the estimated state variance for these state estimators.While various localizer options exist, this study focuses on those utilizing extended Kalman filters and factor graph methods. Unlike methods like NDT and ICP algorithms, extended Kalman filters and factor graph based approaches guarantee bounding of estimated state uncertainty and have been extensively researched for integrity monitoring.Common variance analysis, employed for sensor readings and state estimators, has limitations, primarily focusing on non-faulted scenarios under nominal conditions. This approach proves impractical for real-world scenarios and falls short for safety-critical applications like autonomous vehicles (AVs).To overcome these limitations, this thesis utilizes a dedicated safety metric: integrity risk. Integrity risk assesses the reliability of a robot’s sensory readings and localization algorithm performance under both faulted and non-faulted conditions. With a proven track record in aviation, integrity risk has recently been applied to robotics applications, particularly for evaluating the safety of lidar localization.Despite the significance of improving localization integrity risk through laser landmark manipulation, this remains an under explored territory. Existing research on robot integrity risk primarily focuses on the vehicles themselves. To comprehensively understand the integrity risk of a lidar-based localization system, as addressed in this thesis, an exploration of lidar measurement faults’ modes is essential, a topic covered in this thesis.The primary contributions of this thesis include: A realistic error estimation method for state estimators in autonomous vehicles navigating using pole-shape lidar landmark maps, along with a compensatory method; A method for quantifying the risk associated with unmapped associations in urban environments, enhancing the realism of values provided by the integrity risk estimator; a novel approach to improve the localization integrity of autonomous vehicles equipped with lidar feature extractors in urban environments through minimal environmental modifications, mitigating the impact of unmapped association faults. Simulation results and experimental results are presented and discussed to illustrate the impact of each method, providing further insights into their contributions to localization safety.
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Title: Using Niobium surface encapsulation and Rhenium to enhance the coherence of superconducting devices
Creator: Crisa, Francesco
Date: 2024
Description: In recent decades, the scientific community has grappled with escalating complexity, necessitating a more advanced tool capable of tackling...
Show moreIn recent decades, the scientific community has grappled with escalating complexity, necessitating a more advanced tool capable of tackling increasingly intricate simulations beyond the capabilities of classical computers. This tool, known as a quantum computer, features processors composed of individual units termed qubits. While various methods exist for constructing qubits, superconducting circuits have emerged as a leading approach, owing to their parallels with semiconductor technology.In recent years, significant strides have been made in optimizing the geometry and design of qubits. However, the current bottleneck in the performance of superconducting qubits lies in the presence of defects and impurities within the materials used. Niobium, owing to its desirable properties, such as high critical temperature and low kinetic inductance, stands out as the most prevalent superconducting material. Nonetheless, it is encumbered by a relatively thick oxide layer (approximately 5 nm) exhibiting three distinct oxidation states: NbO, NbO$_2$, and Nb$_2$O$_5$. The primary challenge with niobium lies in the multitude of defects localized within the highly disordered Nb$_2$O$_5$ layer and at the interfaces between the different oxides. In this study, I present an encapsulation strategy aimed at restraining surface oxide growth by depositing a thin layer (5 to 10 nm) of another material in vacuum atop the Nb thin film. This approach exploits the superconducting proximity effect, and it was successfully employed in the development of Josephson junction devices on Nb during the 1980s.In the past two years, tantalum and titanium nitride have emerged as promising alternative materials, with breakthrough qubit publications showcasing coherence times five to ten times superior to those achieved in Nb. The focus will be on the fabrication and RF testing of Nb-based qubits with Ta and Au capping layers. With Ta capping, we have achieved the best T1 (not average) decay time of nearly 600 us, which is more than a factor of 10 improvements over the bare Nb. This establishes the unique capping layer approach as a significant new direction for the development of superconducting qubits.Concurrently with the exploration of materials for encapsulation strategies, identifying materials conducive to enhancing the performance of superconducting qubits is imperative. Ideal candidates should exhibit a thin, low-loss surface oxide and establish a clean interface with the substrate, thereby minimizing defects and potential sources of losses. Rhenium, characterized by an extremely thin surface oxide (less than 1 nm) and nearly perfect crystal structure alignment with commonly used substrates such as sapphire, emerges as a promising material platform poised to elevate the performance of superconducting qubits.
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