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Title: AN EVALUATION OF THE FEASIBILITY OF AN ONLINE FAMILY-BASED INDICATED PREVENTION PROGRAM FOR ADOLESCENT EATING DISORDERS
Creator: Lebow, Jocelyn R.
Date: 2011-10, 2011-12
Description: Adolescent eating disorders are highly impairing class of mental illness, marked by chronicity and recurrence. Data indicate that early...
Show moreAdolescent eating disorders are highly impairing class of mental illness, marked by chronicity and recurrence. Data indicate that early intervention, before anorexia nervosa (AN) or bulimia nervosa (BN) symptoms become entrenched, leads to an increased likelihood of positive outcomes (Fisher, Schneider, Burns, Symons & Mandel 2001; Le Grange, Loeb, Van Orman & Jellar, 2004). As such, numerous prevention programs have been developed for adolescent eating disorders, with mixed success (Shaw, 2008, Stice, Shaw & Marti, 2007). Most recently, programs have utilized the technology of the Internet to make prevention and early intervention more accessible and cost effective for affected teens and families. The current study assessed the feasibility of an original Internet-based indicated prevention program for families of adolescents with subsyndromal eating disorders. The program was based on the empirically-supported Family Based Treatment (FBT) for adolescent AN and BN. Seven families (comprised of 7 caregivers and 7 adolescents with subthreshold levels of eating disorder symptoms) were enrolled in the study, and 4 families successfully completed all program requirements. Four separate aims were assessed including: evaluation of program acceptability, identification of recruitment and retention patterns, assessment of program compliance and dosage received, and analysis of preliminary outcomes. Results suggested that the program was acceptable to all participants, and that the program format and content were positively received. Preliminary outcome data was limited due to the small sample size, however, descriptive analyses showed that the program had a significant effect on the reduction of all cognitive and behavioral eating disorder symptoms, as well as on the reduction of adolescent depressive symptoms. Adolescent ix self esteem was not significantly impacted by program participation. Compliance results were less straightforward. Program adherence was mixed, and further investigation is needed to clarify patterns of compliance and retention. Finally, the recruitment strategies used were found to not be feasible. Despite a wide-ranging and multi-faceted recruitment strategy, rates were very slow. Further, a large percentage of interested potential participants had to be excluded, calling into question the appropriateness of the applicant pool that was accessed through the implemented program of recruitment. Implications of these findings, possible explanations and suggestions for future research are discussed.
Ph.D. in Psychology, December 2011
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Title: MEDIATORS FOR QUALITY OF LIFE IN SURVIVORS WITH BRAIN INJURY
Creator: Johnson, Kristina S.
Date: 2017, 2017-07
Description: Injury to the brain can range in cause, severity, and outcomes. Individuals with brain injury may experience both physical and cognitive...
Show moreInjury to the brain can range in cause, severity, and outcomes. Individuals with brain injury may experience both physical and cognitive impairments. Not only can a patient experience a wide range of symptoms, these symptoms also can vary drastically in severity. Research has shown that these symptoms play a role in a person’s quality of life following injury: the worse a person’s symptoms are, the lower they report their quality of life. However, recent research suggests that psychosocial factors may mediate the relationships between disability severity and quality of life across multiple rehabilitation populations. Two of the previously researched psychosocial constructs include social support and a sense of mastery over the disability or disease. The purpose of this study was to examine a structural model hypothesizing the mediating role of these two constructs on the relationship between symptom severity and quality of life among adults with brain injury. Participants in this study included 183 individuals with brain injury recruited through state brain injury organizations across the United States to participate in an online survey study. Using structural equation modeling (SEM), results demonstrated good model fit. (χ2(15, n = 183) = 13.68). Normed Bentler-Bonnet fit index (NFI) was .97; Goodness-of-Fit statistic (GFI) was .98; Adjusted-goodness-of-fit (AGFI) was .96; and Comparative fit index (CFI) was 1.00 (indices exceeding .90 indicate acceptable fit). Examination of the direct effects showed that perceived social support and sense of mastery are negatively associated with symptom severity (-.19 and -.66 respectively). Additionally, perceived social support was positively associated with mastery (.30). Both mastery and social support were moderately related to quality of life (.46 and .53, respectively). Rmediation analysis revealed perceived social support and mastery fully mediate the relationship between symptom severity and quality of life. Additionally, mastery partially mediated the relationship between social support and quality of life. These findings highlight the importance of incorporating these psychosocial factors into clinical interventions with hopes of increasing levels of perceived social support and mastery, and ultimately promoting quality of life. Further research is needed to explore the best strategies to increase support and mastery within the brain injury population and to identify additional psychosocial factors that may be mediators of quality of life.
M.S. in Psychology, July 2017
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Title: ESSAYS IN ENVIRONMENTAL FINANCE
Creator: Li, Jing
Date: 2013, 2013-07
Description: The Clean Development Mechanism (CDM) is a mechanism de ned in the Ky- oto protocol that incentivizes parties to the protocol to fund...
Show moreThe Clean Development Mechanism (CDM) is a mechanism de ned in the Ky- oto protocol that incentivizes parties to the protocol to fund sustainable development projects in countries that are not party to the protocol. In the rst chapter of this paper, I introduce the CDM and how the nancing mechanism works. In the second chapter, I analyze a target contract nancing structure for di erent CDM projects in order to see under what conditions the nancing structure is e cient and to explore the contract's allocation of pro t among the rms. In the two broad categories of CDM projects I consider, I nd the optimal investment decision for the investor and for the overall system. I also analyze how the residual value of technology would a ect the nancing, target contract's e ciency, and allocation of pro t. In the third chapter, I conduct empirical analysis on the actual CDM outputs, Certi ed Emission Reduction units (CERs), for a sample of wind CDM projects in China. I nd that CDM projects greatly under perform relative to the promises they make. Based on this under-performing records, in the fourth chapter, I analyze the economic bene ts investors could gain if they were able to directly fund a portfolio of CDM projects and obtain returns from the anticipated CER issuances and underlying energy generated from the portfolio of CDM projects. I consider a variety of funding constraints that the CDM fund/portfolio manager (CDM-PM) may face and determine their economic performance against actual CDM project data for wind CDM projects in China.
PH.D in Management Science, July 2013
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Title: MINIMIZING SALMONELLA CONTAMINATION IN SPROUTS BY CONTROLLING THE IRRIGATION CONDITIONS DURING GERMINATION
Creator: Xie, Jing
Date: 2014, 2014-07
Description: The objective of this study was to examine whether the proliferation of Salmonella can be minimized during sprouting by controlling the...
Show moreThe objective of this study was to examine whether the proliferation of Salmonella can be minimized during sprouting by controlling the irrigation conditions using seeds that have been either treated or not treated with 20,000 ppm of calcium hypochlorite, Ca(OCl)2. 200 g of alfalfa seeds spiked with 2 g (or 1 %) of inoculated seeds (containting~1 log cfu/g of Salmonella) were allowed to germinate in a glass jar or in an automatic sprouter (EasyGreen) for 5 days at room temperature. The sprouts germinated in the automatic sprouters were irrigated with either sterile tap water or chlorinated water (containing 100 ppm of calcium hypochlorite) at various frequencies (once every 1, 2 or 4 h); the sprouts germinated in glass jar were rinsed every 24 h with sterile tap water. The same growth studies were performed on seeds treated with 20,000 ppm Ca(OCl)2 for 15 min prior to sprouting. Sprout samples were taken daily and analyzed for the level of Salmonella using the three-tube most probable number method as described in the FDA BAM. Seed treatment with 20,000 ppm Ca(OCl)2 reduced Salmonella level in seeds to a level that was below the detection limit (< -2.5 log MPN/g). The pathogen was not detected during five days of germination in automatic sprouters or jars. Using untreated seeds, the level of Salmonella changed from an increase of ~ 7 log MPN/g in sprouts grown in jars and irrigated once every 24 h to an increase of ~ 4 log MPN/g during sprouting in the automated sprouters and irrigated once every 1 h. Irrigation with chlorinated water although inhibited Salmonella re-growth but affected the quality of sprouts. Overall, seed treatment combined with frequent irrigation with tap water or chlorinated water can control the level of Salmonella to an undetectable level during sprouting.
M.S. in Food Safety and Technology, July 2014
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Title: MOTION ESTIMATION METHODS FOR RESPIRATORY GATED SPECT
Creator: Hurtado Jaramillo, Juan Sebastian
Date: 2014, 2014-12
Description: Single photon emission computed tomography (SPECT) is a type of nuclear imaging test that is used for detection of cardiac diseases....
Show moreSingle photon emission computed tomography (SPECT) is a type of nuclear imaging test that is used for detection of cardiac diseases. Unfortunately it suffers from several image degrading factors, including respiratory motion, that can affect the accuracy of diagnosis. Four-dimensional (4D) respiratory gated SPECT helps to correct this issue by performing the acquisition at several intervals and applying motion-compensated reconstruction methods. With this in mind, and to improve 4D reconstruction, three different motion estimation methods (i.e., optical flow equation, center of mass, and template matching) are applied in this project. Three different sets of dose levels are simulated using NCAT and one set of clinical data is used. The results for motion estimation on simulated data show that the template matching methods have better performance overall. Additionally, noise reduction by means of a spatial smoothing filter helps on the reduction of the average error. Rotational motion estimation using principal component analysis (PCA) was also studied to examine if there can be improvements over the translational motion methods. The initial outcome is that there is a small rotation that can be detected on the ideal reconstruction; the compensation of this rotation also helps to reduce the error obtained from translational motion, albeit by a small margin. Unfortunately, the same cannot be said when noisy reconstructions were used.
M.S. in Electrical Engineering, December 2014
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Title: STIGMA AND MENTAL ILLNESS: THE ROLE OF STEREOTYPE THREAT ON PERFORMANCE OF COGNITIVE MEASURES
Creator: Hautamaki, Julie Bilyeu
Date: 2013, 2013-05
Description: Deficits in cognitive functioning observed in people with schizophrenia are well-documented; however, social psychologists recognize that...
Show moreDeficits in cognitive functioning observed in people with schizophrenia are well-documented; however, social psychologists recognize that additional societal factors, such as stigma and discrimination, may further contribute to these observed deficits in functioning. This study investigated the role of stereotype threat on cognitive functioning of people with schizophrenia. This group encounters stigma in various realms such as employment, relationships and housing. The negative stereotypes regarding this population have been well-documented and studied. In the current study, 60 participants were randomized into a control or stereotype condition. The participants completed a series of cognitive tests and the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I). Participants in the stereotype threat condition were primed with a statement and questions to induce stereotype threat. The order of test administration was part of the threat induction. Stereotype threat was not found to impact the performance of cognitive measures for this group. In-group identification, stigma endorsement, and anxiety levels did not predict performance on cognitive measures.
PH.D in Psychology, May 2013
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Title: Polymorphic Network-on-Chip Datapath Architecture for Reconfigurable Computing Machines
Creator: Weber, Joshua
Date: 2012-04-18, 2012-05
Description: Polymorphic processors have considerable advantages in performance over existing reconfigurable designs. Polymorphic processors combine the...
Show morePolymorphic processors have considerable advantages in performance over existing reconfigurable designs. Polymorphic processors combine the flexibility and ease of a general purpose processor with the performance optimizations made possible through reconfigurable arrays. Polymorphic processors provide all the ease of programming from a traditional general purpose processor while incorporating the significant performance gains that can be realized using reconfigurable arrays. Polymorphic processors can be categorized by the level of integration between the general purpose processor and the reconfigurable array. At coarse levels of integration, the processor and reconfigurable array execute independently and exchange data utilizing bus structures. These systems perform robustly for high level datadriven optimizations, allowing large segments of processing to be quickly performed on fast reconfigurable resources. However, the overhead of data transfer between the processor and array limits the benefit to fine grained optimizations. Other architectures attempt a tight coupling of reconfigurable arrays, placing them within the processor as reconfigurable coprocessors and functional units. This technique allows fine grained optimizations of small scale, highly repeated computations, but finds it difficult to replicate the gains made in large coarse grained optimizations. To achieve an even more tightly coupled design than any prior work, the fundamental architecture of the processor is changed. The datapath of the processor is eliminated and replaced with a network-on-chip communications framework. This framework connects a system of reconfigurable arrays. Some of these reconfigurable blocks are tasked with execution of standard, general purpose processor computations, emulating the standard pipeline stages of a SPARC processor. Additional reconfigurable blocks are available to the end-user to incorporate custom application specific optimizations. This new polymorphic NoC datapath (PolyNoC) processor is able to provide a more tightly integrated architecture with significant performance advantages. The PolyNoC processor is able to incorporate both fine and coarse grained optimizations, producing a polymorphic processor able to provide performance improvements for a wide range of target applications. This thesis presents the architectural design of the PolyNoC processor. The unique design constraints resulting from the use of the NoC as a datapath will be fully explored. The impact of these constraints will be incorporated into the design of a suitable NoC for the PolyNoC processor. A cycle-accurate simulator of the PolyNoC processor has been constructed. This simulator is used to examine the performance of the PolyNoC processor when executing unmodified, industry standard benchmark programs. To demonstrate the advantages of application specific extensions to the processor, accelerators are added for each benchmark. The performance of the Poly- NoC processor is promising.
Ph.D. Computer Science, May 2012
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Title: AIRFOIL LONGITUDINAL GUST RESPONSE IN ATTACHED, SEPARATING, AND DETACHED SURGING FLOW
Creator: Weirich, Jeremy Michael
Date: 2013, 2013-12
Description: Longitudinally gusting ow over a nominally two dimensional airfoil is exam- ined over a range of incidence angles and reduced frequencies. The...
Show moreLongitudinally gusting ow over a nominally two dimensional airfoil is exam- ined over a range of incidence angles and reduced frequencies. The response of the airfoil to these gusting ows is compared with classical theory, and is found to follow theory moderately well at low incidence angles across all reduced frequencies. At high incidence angles, the predictive power of the classical model is found to decrease signi cantly. The aerodynamic forces are also decomposed into circulatory and non- circulatory e ects and their relative strength is examined. The circulatory e ects are found to be minimal and constant at low incidence angles, while high incidence angles show strong variation, indication that the wake structure experiences signi - cant changes. The noncirculatory e ects are found to depend linearly on the reduced frequency and a ect the ow more strongly at lower incidence angles. An argument is made for the utility of dividing analysis of the ow into attached ow, separating ow, and fully detached ow regimes. The division is clear when examining how the normalized force coe cients change with reduced frequency, and provides a useful tool for predicting the transition of the ow between regimes.
M.S. in Aerospace Engineering, December 2013
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Title: EVALUATION OF TIME-FREQUENCY DISTRIBUTIONS FOR ULTRASONIC IMAGING APPLICATIONS
Creator: Lu, Juan
Date: 2013-05-01, 2013-05
Description: This thesis presents the performance evaluation of generalized time-frequency distributions (GTFD) and model-based time-frequency (TF)...
Show moreThis thesis presents the performance evaluation of generalized time-frequency distributions (GTFD) and model-based time-frequency (TF) estimation of ultrasonic signals. Two new TF distributions which are related to generalized time-frequency distribution have been examined. These methods are singular value decomposition of Choi-Williams distribution (CWD-SVD), and 2D (time and frequency) Gaussian kernel applied to generalized time-frequency distribution. The application of Short-Time Fourier Transform (STFT) is studied for chirplets estimation. Then, the Wigner distribution (also called the Wigner-Ville distribution) of estimated Chirplets yield a precise TF representation. The performance of the STFT, the Morlet wavelet transform, the Wigner distribution (WD), the CWD and the CWD-SVD are compared. CWD-SVD is a very effective algorithm to keep the high clarity of the Wigner distribution and to suppress the undesirable cross-terms resulting from multi-component signals. The Gaussian echo model is used to obtain the analytical TF distribution. For CWD the proper range of exponential kernel parameter, , is attained. This range allows CWD to sustain a high concentrated auto-terms and significant suppression of cross-terms. For this range of the CWD-SVD extracts high clarity auto-terms and facilitate eliminating the residual cross-terms. To remove the cross-terms, singular value decomposition algorithm extracts basis functions corresponding to auto-terms. After discarding the basis functions and singular values of the cross-terms and noise, the basis functions and their singular values of auto-terms are used to reconstruct the TF distribution. The results of multi-component Gaussian echoes with significant time and frequency overlaps show that the CWD-SVD is able to eliminate residual cross-terms for xi which the CWD failed to eliminate. The numerical analysis of multi-component Gaussian echoes indicates that CWD-SVD has the ability to resist noise resulting in accurate estimates of center frequencies and arrival times. The generalized time-frequency distribution with 2D Gaussian kernel is able to separate two extremely close Gaussian echoes in the time-frequency domain. In this study, typical values of the 2D Gaussian kernel parameters for efficient cross-terms elimination are provided. The relationship between the kernel's parameters and Gaussian echoes' parameters is deduced. A practical method for TF analysis is to decompose the signal into sparse chirplets. Decomposition requires chirplet parameter estimation. In this study, the parameters of a signal which is composed of two overlapping chirplets are estimated using STFT. By this method the estimation results are found to be accurate confirming that the STFT is an effective method for decomposing and estimating chirplets in a multi-component signal.
M.S. in Electrical Engineering, May 2013
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Title: MEAN-VARIANCE HEDGING WITH TIME CHANGED LEVY PROCESS
Creator: Liu, J Ingran
Date: 2012-11-17, 2012-12
Description: The goal of this thesis is to consider asset pricing model which driven by an exponential time changed process: Brownian motion with time...
Show moreThe goal of this thesis is to consider asset pricing model which driven by an exponential time changed process: Brownian motion with time changing process{ Poisson process. We rst present the characteristic function of the time change exponential Brown motion and its ltration. Second we exhibit the explicit European call pricing formula then discuss the mean-variance hedging method in this thesis.
M.S. in Applied Mathematics, December 2012
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Title: SIMILAR VOICES, SAME PERSPECTIVES? INTERNATIONAL MOVIE REVIEWERS AT THE IMDB
Creator: Gao, Jing
Date: 2012-04-21, 2012-05
Description: Online communities enable people from around the world to interact online. But having the opportunity to speak and being heard are two...
Show moreOnline communities enable people from around the world to interact online. But having the opportunity to speak and being heard are two different issues. In most cases of intercultural communication online, people from different cultures interact in English. Are they still able to bring their own perspectives without using their native language? This study thus focuses on whether or not international voices are heard online and whether or not these voices that find audiences are really differ- ent, as compared to the local voice (i.e., dominant or majority voice). We question whether or not international voices are different, as previous studies on intercultural communication debate over whether or not voices are different by culture. Results of a content analysis show that international and U.S. participants tend to contribute similar content, which contrasts with the common assumption that people from dif- ferent cultures will write differently and resonates with previous studies that have proposed that culture, on its own, is not an effective predictor of online behavior.
M.S. in Technical Communication and Information Design, May 2012
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Title: COMPARING LAGRANGIAN COHERENT STRUCTURES FROM ASSIMILATING OCEAN MODELS TO OCEAN COLOR IMAGES
Creator: Riley, Jordan
Date: 2012-01-04, 2012-12
Description: Lagrangian coherent structures (LCS) have been used to study transport on the ocean surface. The material barrier and separatrix properties of...
Show moreLagrangian coherent structures (LCS) have been used to study transport on the ocean surface. The material barrier and separatrix properties of LCS provide means to compare data-assimilative ocean models. LCS obtained from these models are compared to ocean color images and satellite derived products such as chlorophyll concentration and sea surface temperature from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Terra and Aqua satellites. The ability of the LCS to match the satellite images provides insight into the accuracy of the ocean models in capturing predominant ow structures. Two of the ocean model systems use the U.S. Navy Coastal Ocean Model (NCOM), and two model systems use the HYbrid Coordinate Ocean Model (HYCOM). Speci cally, the model systems are the Intra American Seas Nowcast/Forecast System (IASNFS), the NCOM American Seas, the HYCOM + NCODA Global 1/12 , and the HYCOM + NCODA Gulf of Mexico 1/25 .
M.S. in Mechanical and Aerospace Engineering, December 2012
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Title: CONTROL OF DOUBLY-FED INDUCTION GENERATOR FOR WIND APPLICATION
Creator: Guo, Jing
Date: 2012-05-03, 2012-05
Description: With growing concerns over environmental pollution and globe warming, renewable energy has received considerable attention as an alternative...
Show moreWith growing concerns over environmental pollution and globe warming, renewable energy has received considerable attention as an alternative energy resource of electricity production. Because of the immense potential of wind energy on the earth, wind power generation has gained significant popularity over recent years. From this research, it has been concluded that there is a constant need to reduce the size and rating of power electronic converters, improve efficiency of the electromechanical system and make the system more reliable by eliminating the gearbox. This thesis analyzes a doubly fed induction generator (DFIG) drive system for distributed wind generation systems. The structure of a doubly fed induction generator is similar to that of an induction generator. To illustrate the operation principle and control strategy of a DFIG clearly, the fundamentals and control principle of an induction generator have been discussed. For DFIG control, two closed control loops are designed-active power control loop and rotor speed control loop; and they can be switched between each other. By utilizing active power control loop, the output power of the system can be regulated to meet different customer requirements and their dependence on grid electricity can be eliminated, therefore the cost and the power loss on transmission lines can be reduced. On the other hand, by switching to the speed control loop, the system can extract maximum power at different wind speeds, and any extra power can either be stored or sold to the utility for profit. To validate the proposed concept, Finite Element Analysis (FEA) models of a doubly fed induction generator and an induction generator have been built and simulated using the software Magnet®; furthermore, the control systems of these two generators are implemented and simulated in a Matlab/Simulink environment. Finally, a Magnet and Matlab/Simulink co-simulation has been performed for the DFIG. By analyzing the simulation results, the differences between the doubly-fed induction generator and an induction generator have been demonstrated.
M.S. in Electrical Engineering, May 2012
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Title: HYDROGEN BOND CATALYZED EPOXIDATION AND DIHYDROXYLATION OF UNACTIVATED ALKENES
Creator: Kang, Lili
Date: 2011-12, 2011-12
Description: Asymmetric epoxidation and dihydroxylation have been studied over decades using transition metals and chiral ligands. This research focused on...
Show moreAsymmetric epoxidation and dihydroxylation have been studied over decades using transition metals and chiral ligands. This research focused on metal free, hydrogen-bonding activation of the oxidant, such as hydrogen peroxide. In order to activate hydrogen peroxide, different types of catalysts, including BINOLs, calixarenes and carboxylic acids were synthesized, characterized and tested. The activity tests showed that carboxylic acids were able to activate hydrogen peroxide and alkyl hydroperoxides to give epoxides and diols as products. Various carboxylic acids, such as commercial available achiral and chiral carboxylic acids, dicarboxylic acids, as well as synthesized trans- and cis-dicarboxylic acid, were tested with different substrates to maximize the yield and enantioselectivity. A current reaction system uses 10 mol % catalyst, no solvent and provides the epoxide with 70% yield and 60% ee over 24 hours.
M.S. in Chemisty, December 2011
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Title: DISTRIBUTION SYSTEM STATE ESTIMATION
Creator: Li, Lingyan
Date: 2015, 2015-05
Description: This thesis provides a novel method to improve distribution system state estimation by an effective approach to processing bad data in...
Show moreThis thesis provides a novel method to improve distribution system state estimation by an effective approach to processing bad data in measurements. The first part of this research is focused on modeling distribution system state estimation with bad data rejection capability. We apply transmission level model to the distribution level system with specific properties, such as fewer real measurement data for state estimation in the distribution level system, three phase unbalance power flow and so on. For building a robust state estimation model, we optimize the system in the following ways: First, we optimize objective function. We use forecasted load as pseudo measurements. Then we apply different weights to distinguish the forecasted data and actual measurements in the state estimation. Second, we apply three phase power equation in the analysis. We add real power, reactive power, active line power, reactive line flow, voltage magnitude, phase angle and others as nonlinear constraints in the three phase model of state estimation. Third, we flexibly change objective function and constraints in the state estimation model. We can change objective function when state estimation method changes. Meanwhile, we can add power flow and bus limitations in the optimization to avoid state estimation results exceeding power system limitations. Finally, we conduct hybrid calculation. In the first optimization, we filter the bad data. Then, we add another weight to reduce the bad measurement weight and enlarge the good measurement weight. After this process, we get optimized state estimation results. The second part focuses on the implementation of the model. We explain how to preprocess testing case data in this part. The third part is case study. We use IEEE 34 node feeder to test this model. There are four test cases. One test case has no bad data. Other cases have bad data in different types of measurements. We compare these cases with conventional WLS approach. The results obtained from simulation indicate our model has better performance when there is bad data in measurements.
M.S. in Electrical Engineering, May 2015
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Title: COMPARISON OF THE EFFICACY OF THREE SANITIZERS WITH 20,000 PPM CALCIUM HYPOCHLORITE FOR INACTIVATION OF SALMONELLA ON ARTIFICIALLY CONTAMINATED ALFALFA SEEDS
Creator: Li, Qing
Date: 2015, 2015-12
Description: This study evaluated the efficacy of three alternative sanitizers, acidified sodium chlorite (ASC, also known as Sanova), stabilized oxychloro...
Show moreThis study evaluated the efficacy of three alternative sanitizers, acidified sodium chlorite (ASC, also known as Sanova), stabilized oxychloro-based sanitizer (SOC, also known as Germin-8-or), and Tsunami 100 in comparison with 20,000 ppm Ca(OCl)2 for treatment of alfalfa seeds artificially inoculated with Salmonella. Small-scale experiments were conducted to determine the best treatment conditions for each sanitizer and how the initial Salmonella contamination level on seeds or Salmonella type may have on the efficacy of the sanitizers. Large-scale studies were performed to evaluate the commercial applicability of these sanitizers. As a comparison, seeds were also treated with 20,000 ppm Ca(OCl)2 for 15 min. To determine the optimal treatment condition, ten g of seeds containing 103 CFU/g (seed lot 1) or 105 CFU/g (seed lot 2) of S. Typhimurium expressing green fluorescent protein was treated with different concentrations of ASC, SOC, and Tsunami 100 for different period of treatment time. Results showed that the efficacy of ASC and SOC increased with increasing concentrations (up to 1500 ppm) and treatment time (up to 3 h); however, the germination rates for seeds treated with > 1200 ppm of either sanitizer was < 80%. When seeds from lot 1 were treated with 800 ppm of ASC or SOC for 3 h, the level of Salmonella reduced, respectively, by 2.6 log units or >2.5 log units to an undetectable level, compared with the 1.1 log unit decrease observed in seeds treated with Ca(OCl)2. When seeds from seed lot 2 (5 log units) were treated with 800 ppm of ASC or SOC for 3 h, the level of Salmonella were reduced by 3.8 log units or >4.3 log units to an undetectable level, respectively, compared with the 2 log units decrease observed in seeds treated with Ca(OCl)2. Treatment with 80 ppm of Tsunami 100 from 10 min to 24 h kept the germination rate higher than 85% but only reduced the Salmonella count by 0 to 1.8 log units. Between two seed lots, results of ASC showed that sanitizer could reduce more pathogen when the seeds contained higher initial Salmonella level. Ten g of seeds containing 105 CFU/g of four-strain cocktail of Salmonella was treated with ASC and SOC by optimal treatment condition. SOC and ASC eliminated Salmonella number by 2.8 and 1.6 log units respectively, less effective compare with the treatment of seed lot 1. For large-scale runs, 1 kg of seeds spiked with 1 % (w/w) of inoculated seeds containing 105 CFU/g of S. Typhimurium was treated with SOC and ASC under optimal treatment conditions. Salmonella level in seeds treated with 800 ppm SOC or ASC for 3 h decreased by 3.9 or 3.6 log units, compared with a 3.3 log reduction in seeds treated with 20,000 ppm Ca(OCl)2. The stabilized oxychloro-based sanitizer may provide an alternative seed treatment method for sprout growers.
M.S. in Food Safety and Technology, December 2015
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Title: THE CHARACTERIZATION OF TWO THERMOPHILIC STRAINS CONCERNING BIO-DESULFURIZATION OF DIBENZOTHIOPHENE BY THE 4S PATHWAY
Creator: Li, Enze
Date: 2016, 2016-05
Description: A moderately thermophilic Mycobacterium strain (denoted Myco-U) was isolated in our lab as a contaminant during the cultivation of another...
Show moreA moderately thermophilic Mycobacterium strain (denoted Myco-U) was isolated in our lab as a contaminant during the cultivation of another thermophilic Paenibacillus strain, and has been proved to harbor the genes that encode the enzymes for dibenzothiophene (DBT) biodegradation via the 4S pathway; this makes it possible to efficiently remove organosulfur compounds (e.g. DBT and DBTO2) from the crude petroleum. Through directed evolution (continuous passage and selection with increasing temperature), the Myco-U strain has shown moderate capacity of metabolizing DBT to 2-hydroxybiphenyl (2-HBP) by the 4S pathway at a thermophilic temperature (~53 ℃). In the middle-to-late stages of the selections, a stubborn contaminant (denoted Bacillus X) arose and has remained difficult to get rid of from our medium and cultures ever since, leading to a persistent contamination and repetition of our experiments. The reason why Bacillus X is regarded as a contaminant is that it does not obtain sulfur by the expected means (e.g., DBT desulfurization), but utilizes the tiny amount of sulfate from the vitamin mix and 50 μg/ml yeast extract in our medium to grow. This is confirmed by the facts that Bacillus X does not yield any detectable 2-HBP, and a significant difference of growth has been detected between cultures with DBT as the sole sulfur source and the positive controls, which employs Na2SO4 as sulfur source. Through 16S rDNA amplification, cloning, and sequencing, Bacillus X was identified as a Bacillus species, and shows the highest homology (99 % identical) to a specific uncultured bacterium clone (NCBI #Accession: JN882111.1). The chromogenic mechanism and impacts of pH and carbonate upon the Gibbs assay, by which 2-HBP is quantified, were investigated. When DBT is absent or at undetectably low levels, cultures measured by the assay display a yellowish-to-brownish background after adding the Gibbs reagent (2,6-dichloroquinone-4-chloroimide). According to our results, the Gibbs reaction prefers alkaline conditions and pH 8.0 ranks the optimal (compared with pH 7.0, 7.5, 8.5 and 9.0) at which the maximum A610nm is detected.
M.S. in Biology, May 2016
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Title: CYBER ATTACKS AGAINST STATE ESTIMATION IN POWER SYSTEMS: VUNERABILITY ANALYSIS AND PROTECTION STRATEGIES
Creator: Liu, Xuan
Date: 2015, 2015-07
Description: Power grid is one of the most critical infrastructures in a nation and could suffer a variety of cyber attacks. With the development of Smart...
Show morePower grid is one of the most critical infrastructures in a nation and could suffer a variety of cyber attacks. With the development of Smart Grid, cyber security has become an area of growing concern. False data injection attack has recently attracted wide research interest. This thesis proposes a false data attack model with incomplete network information and develops optimal attack strategies for attacking load measurements and the real-time topology of a power grid. The impacts of false data on the economic and reliable operations of power systems are quantitatively analyzed in this thesis. To mitigate the risk of cyber attacks, a distributed protection strategies are also developed. It has been shown that an attacker can design false data to avoid being detected by the control center if the network information of a power grid is known to the attacker. In practice, however, it is very hard or even impossible for an attacker to obtain all network information of a power grid. In this thesis, we propose a local load redistribution attacking model based on incomplete network information and show that an attacker only needs to obtain the network information of the local attacking region to inject false data into smart meters in the local region without being detected by the state estimator. A heuristic algorithm is developed to determine a feasible attacking region by obtaining reduced network information. This thesis investigates the impacts of false data on the operations of power systems. It has been shown that false data can be designed by an attacker to: 1) mask the real-time topology of a power grid; 2) overload a transmission line; 3) disturb the line outage detection based on PMU data. To mitigate the risk of cyber attacks, this thesis proposes a new protection strategy, which intends to mitigate the most damaging effect of LR attacks on power system operation. The objective is to mitigate the damage effects of false data injection attacks by increasing the attacking cost of an attacker. This is achieved by protecting a small set of critical measurements. To further reduce the computation complexity, we also propose a mixed integer linear programming approach to separate the power grid into several subnetworks, then distributed protection strategy is applied to each subnetwork. The results of this thesis reveal the mechanism of local false data injection attacks and highlight the importance and complexity of defending power systems against false data injection attacks.
Ph.D. in Electrical and Computer Engineering, July 2015
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Title: CHANGES OF BACTERIAL SPECIES AND HEME PROTEIN LEVEL IN ACTIVATED SLUDGE COMMUNITIES ACCLIMATED TO LOW AERATION
Creator: Li, Hainan
Date: 2016, 2016-05
Description: Increasing oxygen utilization of activated sludge under low dissolved oxygen (DO) conditions can lead to energy savings in wastewater...
Show moreIncreasing oxygen utilization of activated sludge under low dissolved oxygen (DO) conditions can lead to energy savings in wastewater treatment systems. Adaptation of sludge communities to low oxygen conditions may be facilitated by increased expression of heme proteins. One way to assess heme protein expression in sludge is to analyze the species present in the sludge community during the adaptation process. In the work reported here, growth of a sludge culture adapted by Kunkel to low aeration for 48 weekly passages was continued for an additional 26 passages (182 days). The activated sludge was cultured in synthetic wastewater under low DO conditions. Temperature, dissolved oxygen, and specific oxygen uptake rates (SOUR) were measured at the end of each weekly passage. The community structures of passages 50, 53 and 65 were determined by 16S rDNA cloning techniques. The type of heme present was identified using the pyridine hemochromogen method. The SOUR values measured increased slightly in the first part of the experiment, when the culture DO was very low, but then decreased in the latter part of the experiment, when the culture DO increased. The community structure diversity in passage 50 in Kunkel’s study and passage 50 from this work are totally different in terms of species present, even though the two cultures were both derived from Kunkel’s passage 48 and were grown under conditions which were matched as closely as possible for two additional passages. This indicates that the community structure is highly sensitive to small changes in growth conditions. From the point of view of types of hemoglobin (Hb), the community became more diverse by passage 53, containing all three types of truncated Hb (trHbN, trHbO, and trHbP), possibly due to the need for NO scavenging and oxygen transfer enhancement. The proportion of cells that synthesize truncated Hb decreased slightly through passages 50 to 53 to 65. The percentage of cells that encode FlavoHbs decreased from 84 % to 50 % by passage 65. Overall there was an increase in Hb expression from passage 50 to passage 65. Heme b expression in the sludge culture was confirmed. Successful adaptation of the sludge culture to low DO conditions via enhancement of oxygen uptake was not obvious in this study. Yet the overall tendencies of SOUR and Hb expression suggest that it is possible to acquire a culture more efficient in oxygen uptake if a stable low aerobic environment can be maintained for an extended period.
M.S. in Biology, May 2016
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Title: INVESTIGATION OF OXYGEN GENERATION DURING THE OPERATION OF LITHIUM-ION CELLS USING IN-SITU FLUORESCENCE SPECTROSCOPY
Creator: Li, Mo
Date: 2016, 2016-07
Description: An ex-situ fluorescence spectroscopy system was set up and utilized to study the interaction of fluorescent dyes with an oxygen quencher. The...
Show moreAn ex-situ fluorescence spectroscopy system was set up and utilized to study the interaction of fluorescent dyes with an oxygen quencher. The Stern-Volmer relationship was obtained and fitted to correlate the partial pressure of oxygen to the dye fluorescence intensity. The oxygen quenching constant α for 30 μM 9,10-dimethylanthracene_(DMA) dissolved in the mixture of ethylene carbonate_(EC) and dimethyl carbonate_(DMC) (1:1 volume ratio) were 0.69/0.62 at high/low partial pressure of oxygen. Operation of the self-made pouch cells with LiCoO2 as the cathode material was examined by charging/discharging at C/10. The discharge capacities were 107 and 104 mAh/g for the pouch cell both with and without the optical probe, which indicates that the optical probe did not significantly affect the performance and capacity of the cell. The optical probe was inserted into the pouch cell to measure the fluorescence intensity of the dye that was dissolved in the electrolyte. Time series experiments before charging demonstrated that the fluorescence intensity was stable for at least 24 hours. However, the fluorescence intensity decreased abruptly as the voltage of the pouch cell increased during the initial stages of charging, which means that the dye (DMA) could not be employed to detect the oxygen generated in the cell. Both the real-time fluorescence spectroscopy and the cyclic voltammetry illustrated that this dye was not suitable for the in-situ fluorescence tests. The electrochemical stability at room temperature of different dyes such as anthracene, Palladium (II) meso-tetrakis (pentafluorophenyl porphyrin)_(PTTFPP) and Platinum octaethylporphyrin_(PtOEP) were examined in the organic solvents used in the electrolytes in Li-ion cells. Cyclic voltammograms of anthracene and PTTFPP showed oxidation peaks at 2V and reduction peaks at around 1V, with the possible formation of the radical anion causing spectral changes. The chemical compound 1-hexyl-3- methylimidazolium bis (trifluormethylsulfonyl)imide_(HMIM BTI) was electrochemically stable, but the fluorescence intensity was too low (5% of dye DMA) to be used in the in-situ detection of oxygen. As a result, more work must be performed in the future to find a suitable dye. Keywords: fluorescence spectroscopy, in-situ Li-ion cell operation, quencheroxygen, the Stern-Volmer relationship
M.S. in Chemical Engineeering, July 2016
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