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Title: Role of Respiratory Enzymes on Growth of Pseudomonas aeruginosa in Luria-Bertani and Artificial Urine Media
Creator: Hu, Yuyao
Date: 2018
Description: Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes many hospital-acquired infections. The treatment of P. aeruginosa...
Show morePseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes many hospital-acquired infections. The treatment of P. aeruginosa infections is difficult due its multiple defense and adaptive mechanisms. One of these mechanisms is the flexibility of its respiratory chain. The human cell respiratory chain is composed of four respiratory enzymes with low mechanistic flexibility. On the other hand, the respiratory chain of P. aeruginosa contains 23 respiratory enzymes that ensure survival under harsh conditions. To elucidate the physiologic role of these respiratory enzymes, our research compared the growth parameters of wild type P. aeruginosa and nine separate respiratory enzyme mutants, in both LB and artificial urine media (AUM). The deletion mutants include the sodium-translocating NADH: quinone oxidoreductase, complex I, succinate dehydrogenase, cytochrome bc1 complex, cytochrome c oxidase and cyanide insensitive terminal oxidase. Our data indicate that the growth curve of the cytochrome bc1 complex knockout mutant showed a significantly lower yield and lower growth rate compared with the wild type in both LB and AUM media. Additionally, the cyanide insensitive terminal oxidase mutant showed a significant lower yield compared with the wild type in LB media growth. These results indicate the important roles of these enzymes in the cell biology of P. aeruginosa.
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Title: Maternal-Fetal Attachment: Does it predict parenting outcomes?
Creator: Desai, Shivani S.
Date: 2018
Description: Maternal-fetal attachment (MFA) predicts critical aspects of the caregiver-child relationship, including parental sensitivity and engagement....
Show moreMaternal-fetal attachment (MFA) predicts critical aspects of the caregiver-child relationship, including parental sensitivity and engagement. However, little is known about the relation between MFA and specific parenting beliefs and attitudes that contribute to these positive parenting behaviors, such as parenting sense of competence and parenting stress. The aim of this longitudinal study was to examine if MFA predicts specific domains of parenting sense of competence and parenting stress when children are two years of age. Participants included 53 mainly Caucasian women with a mean age of 33.9 years. MFA was assessed during pregnancy (mean gestational age = 27.02 weeks) using the Maternal Fetal Attachment Questionnaire. Parenting sense of competence and stress were assessed when the children were 2 years of age with the Parenting Sense of Competence questionnaire and the Parenting Stress Index questionnaire. Results of regression analyses indicated that higher levels of MFA significantly predicted higher levels of parenting satisfaction, a domain of parenting sense of competence. They also indicated that higher levels of MFA predicted lower levels of two domains of parenting stress, including stress associated with attachment and role restriction. These findings suggest that prenatal attachment is important to assess during pregnancy, as it may predict future parenting beliefs and attitudes, including sense of competence and stress.
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Title: SHARING COMMUNITY HOUSING YOUNG PROFESSIONALS IN CHINESE BIG CITIES
Creator: ZHANG, HAOYU
Date: 2018
Description: In the past few decades, China has achieved an unbelievable fast development, from a poor after-war country to the second largest economy in...
Show moreIn the past few decades, China has achieved an unbelievable fast development, from a poor after-war country to the second largest economy in the world. Under the leadership of the Chinese central government and people’s corporate effort, China made significant achievements in its economic growth, modernization construction. With these achievements, Chinese urbanization has gone through a rapid development and expansion process. Nowadays, city living quality and urban development became one of the most popular focal points in Chinese people’s daily life.The Chinese urbanization enters rapid expansion era. Urbanization with Chinese characteristics does bring a rich material life and improve the standard of people’s living. Meanwhile, city problems started to appear and bring inexpediency and troubles to urban resident’s daily life. At the same time when cities are developing, the distance between people seems to get further. Comparing to other groups of people, the young professionals, are facing more challenges in the cities. They are under pressure from intense competition and high living cost. Most of them must live in space with bad conditions and gradually lose confidence under the heavy load from life. They are also in self-enclosed status, losing normal social relationships and scare to communicate with others. In Chinese big cities, having a comfortable space to live and not being lonely seems to be an unattainable wish for the young generation. Meanwhile, as an emerging economic pattern, Sharing Economy started to appear in most countries of the world during past years. China, as one of the largest economies, and a country with extremely high population base and rapid development speed became the best place for sharing economy to be developed. The Chinese urbanization situation gave a massive push to the sharing economy which is highly expected and considered to be able to solve the problem of conflict between people and urban. This thesis aims to prove that the idea of sharing can create an efficient, economical and comfortable living environment for young professionals in Chinese big cities, by looking at the urbanization with Chinese characteristics, young professionals living conditions, the development of sharing economy in China and developing a community prototype. This community will help young people to relieve living stress and rebuild social connections, also become a solution to reduce the conflict between young professionals and urban environment.
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Title: SINGLE-POINT MUTATION OF UBL4A ABOLISHES ITS INTERACTION WITH THE ARP2/3 COMPLEX
Creator: Yao, Qi
Date: 2018
Description: Ubl4A is a member of the ubiquitin-like protein family with multiple functions, such as pro-survival and anti-tumor. Our group previously...
Show moreUbl4A is a member of the ubiquitin-like protein family with multiple functions, such as pro-survival and anti-tumor. Our group previously found that Ubl4A directly interacts with actin-related protein Arp2/3 complex to promote Arp2/3-dependent actin “Y shape” branching formation. However, the binding region of Ubl4A for Arp2/3 still remains unknown. To address this question, we generated several Ubl4A mutant and truncated constructs, and cloned them into a GST vector in which GST was fused in-frame with Ubl4A at the N-terminus. We used Glutathione-beads to purify GST fusion proteins and performed pull-down assay with purified Arp2/3 complex. We show that C-terminus of Ubl4A is the region where the Arp2/3 complex interacts with. A single point mutation (D122A) in Ubl4A C-terminal “DYD” motif can abolish Ubl4A ability to bind Arp2/3. These results indicate that C-terminus, especially D122, is critical for Ubl4A association with Arp2/3.
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Title: ESTIMATES OF FINE AND ULTRAFINE PARTICLE REMOVAL EFFICIENCY FOR RESIDENTIAL HVAC FILTERS USING IN-SITU SIZE-RESOLVED EFFICIENCY MEASUREMENTS
Creator: Zeng, Yicheng
Date: 2018
Description: Central heating, ventilating, and air-conditioning (HVAC) filters are commonly evaluated for their size-resolved particle removal efficiency ...
Show moreCentral heating, ventilating, and air-conditioning (HVAC) filters are commonly evaluated for their size-resolved particle removal efficiency (for particles 0.3 to 10 µm in diameter) by challenging them with a test aerosol in a laboratory setting. However, aerosol measurement and reporting classifications that are most commonly used in regulatory monitoring and building measurements include integral measures of mass-based concentrations (e.g., PM2.5, or the mass concentration of particles smaller than 2.5 µm) or total number concentrations (e.g., total UFPs, or ultrafine particles smaller than 100 nm). Because filter test standards have not traditionally considered these measures, building owners, occupants, and other key personnel cannot make informed decisions on HVAC filtration for these classifications. Moreover, because the removal efficiency for integral measures of total mass and number concentrations are also a function of the underlying particle size distributions that challenge the filter, one must consider the varied sources and size distributions of aerosols that filters encounter in real building applications. This work has two objectives: (1) to measure the in-situ size-resolved particle removal efficiency of a large number of commercially available residential HVAC filters, and (2) to use those size-resolved efficiency data to estimate integral measures of PM2.5 and total UFP removal efficiency for the same filters for typical residential indoor settings based on a literature survey of measured indoor particle size distributions. Particle concentration measurements were made upstream and downstream of a wide range of commercially available filters installed in a central air handling unit in an unoccupied residential apartment unit. A literature review was conducted to gather a variety of indoor particle size distributions (PSDs) from across the world and tri-modal lognormal distributions were fit to each of them. Finally, the particle removal efficiency for each filter for integral measures of indoor UFPs and PM2.5 were calculated for each indoor PSD. In-situ size-resolved measurements indicate that filters with similar rating values but from different manufacturers can have very different removal efficiencies for integral measures of PM2.5 and total UFPs, and that the assumption for indoor PSDs can greatly impact estimates of removal efficiency.
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Title: AN EXPERIMENTAL INVESTIGATION OF THE DYNAMICS OF AN INVERTED SERRATED FLAG
Creator: MURUGESAN PAZHANI, KAUSHIK
Date: 2018
Description: An experimental investigation of the role of leading-edge triangular serrations was conducted to understand the role of free leading edge in...
Show moreAn experimental investigation of the role of leading-edge triangular serrations was conducted to understand the role of free leading edge in large amplitude flapping of an inverted flag. The serrations are in the form of triangles arranged spanwise along the leading edge of the flag model. High – speed camera imaging experiment was conducted in open – loop wind tunnel at air – speeds ranging from 3.3m/s to 6.5m/s. For this velocity range, the non – dimensional bending stiffness (the ratio of bending force to the fluid inertial forces) ranges from 0.285 to 0.073. Flow visualization experiment using PIV technique was conducted for baseline flag and two serrated flags at flow velocity 4.8m/s (bending stiffness – 0.13). At a critical value of the velocity or bending stiffness, the flag oscillations transition from low amplitude asymmetric oscillations to symmetric high amplitude oscillations. This critical velocity is higher for the serrated flags indicating a reduction in the instantaneous lift force. The critical velocity was found to increase as serration height increased for a fixed number of serrations. The serrations create leading edge counter rotating eddy structures that interact with the primary tip vortex formation and breakdown process leading to changes in critical velocity, amplitude and frequency. The flapping amplitude and frequency were found to decrease as serration height increased for a fixed number of serrations. The “shallow” serrations have no effect of serrations while “tall” serrations decrease the non – dimensional flapping frequency and amplitude. The phase averaged velocity results show serrations delay leading edge vortex formations, and flow separation. This leads to decrease in pressure difference causing the serrated flag to deform less than baseline flag. Leading edge vortex formed in serrated flags were observed to be deformed compared to baseline flag leading edge vortex. Vortex deformation is due to serration induced three-dimensional flow effects. Serrated flags exhibit elongated vortical structures from flag tip instead of periodic vortex shedding in rebound phase. Streamlines used for qualitative analysis also shows, serrated flags lack periodic vortex formation and shedding during rebound phase. Using qualitative evidence from streamline plots and vorticity contour plots (elongated vortex structures) it could be stated due to change in leading edge geometry, serrated flags demonstrate a non – VIV flapping.
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Title: Efficiency of Stratification for Ensemble Reduction based on docking scores
Creator: Zhang, Hexi
Date: 2018
Description: Molecular docking has been widely used in structure-based drug design to virtually screen large chemical libraries to predict the prefer...
Show moreMolecular docking has been widely used in structure-based drug design to virtually screen large chemical libraries to predict the prefer conformations ligands that could bind the target site. Protein flexibility is a major issue that could be solved by ensemble docking which is docking to ‘ensemble’ of protein rigid conformations, such as snapshots obtained by molecular dynamics simulations. Our group has developed a method called ‘Efficiency of Stratification’ to evaluate a number of common snapshot selection strategies using a quality metric from stratified sampling (Xie et al. [19]). Docking was performed to four proteins and with each ligand numbers sets of up to five hundred ligands. In this paper, we generated distance matrices based on docking score to analysis the performance of the efficiency of stratification method. We observed that most docking score based score-based distance matrices have had better performance than structure-based distance matrices and with including any structure-based component overwhelms the docking-score component. Only a few ligands are required to get a good distance matrix.
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Title: PRIVACY PRESERVING BAG PREPARATION FOR LEARNING FROM LABEL PROPORTION
Creator: Yan, Xinzhou
Date: 2018
Description: We apply Privacy-preserving data mining standards (PPDM) to the Learning from label proportion (LLP) model to create the Private-preserving...
Show moreWe apply Privacy-preserving data mining standards (PPDM) to the Learning from label proportion (LLP) model to create the Private-preserving machine learning framework. We design the data preparation step for the LLP framework to meet the PPDM standards. In the data preparation step, we develop a bag selection method to boost the accuracy of the LLP model by more than 7%. Besides that, we propose three K- anonymous aggregation methods for the datasets which have almost zero accuracy loss and very robust. After the K-anonymous step, we apply Differential privacy to the LLP model and ensure a low accuracy loss for the LLP modelBecause of the LLP model’s special loss function, not only it is possible to replace all the feature vectors with the mean feature vector within each bag, but also the accuracy loss caused by Differential privacy can be bounded by a small number. The loss function ensures low accuracy loss when training LLP model on PPDM dataset. We evaluate the PPDM LLP model on two datasets, one is the Adult dataset and the other is the Instagram comment dataset. Both of them give empirical evidence of the low accuracy loss after applying the PPDM LLP model.
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Title: THE LATIN AMERICAN EXPORT: IMPLEMENTING LATIN AMERICAN URBAN STRATEGIES TO REDEVELOP AND RECONSTRUCT BRONZEVILLE
Creator: Saldaña Perales, Alejandro
Date: 2018
Description: The district and neighborhood of Bronzeville, located in the Near South Side of Chicago, suffers from crime, unemployment, abandonment, and...
Show moreThe district and neighborhood of Bronzeville, located in the Near South Side of Chicago, suffers from crime, unemployment, abandonment, and urban decay; more so than many of its metropolitan peers such as New York City, Los Angeles, or San Francisco.In Latin America, multidisciplinary operations and strategies focused on the investment in public spaces, mobility, and public assets have been successful in transforming decaying neighborhoods and redeveloping slums and blighted areas turning them into vibrant communities.Contextualizing and abstracting such strategies has the potential to import such ideas into new urban contexts; in this case, the United States of America, and to be implemented over the decaying North American urban fabric.
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Title: Enhancing Charge/Discharge Cycle Stability of NaCrO2 Cathode for Na-ion Batteries via Carbon Coatings
Creator: Shi, Zhepu
Date: 2018
Description: In this study, we report the effects of carbon coating on the electrochemical cycle stability of Na-ion batteries made of NaCrO2 cathodes....
Show moreIn this study, we report the effects of carbon coating on the electrochemical cycle stability of Na-ion batteries made of NaCrO2 cathodes. Various coating approaches and conditions have been investigated for 10-h high energy ball milled NaCrO2. It is shown that mixing the carbon source with NaCrO2 particles before the high-temperature carbonization reaction is a critical step. The solution-based mixing of the carbon source with NaCrO2 leads to the best carbon coating uniformity. Furthermore, carbonization treatment should be limited to 10 min at 650 ℃ in order to prevent the reaction between carbon and NaCrO2 to form chromium carbides. Uniform carbon coating can improve the capacity retention of NaCrO2 over charge/discharge cycles and the best capacity retention achieved in this study is 70% after 50 cycles. Furthermore, once the coating is uniformly distributed, NaCrO2 exhibits a very high specific capacity (140 mAh/g) which is significantly higher than the typical value of 110 mAh/g reported in the literature. The unusually high specific capacity observed is attributed to the enhancement of Na-ion intercalation and de-intercalation rates at the electrode/electrolyte interface because of the presence of the carbon coating.
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Title: Correlating Veterans' Employment Status by Analysis of Recovery from the Recovery Assessment Scale-Short Form
Creator: Avezuela-Perez, Margaret
Date: 2020
Description: Past research has examined the low employment rates in veterans with serious mental illness (SMI) (Zivin et al., 2011) and the research...
Show morePast research has examined the low employment rates in veterans with serious mental illness (SMI) (Zivin et al., 2011) and the research suggests that the benefits of employment for veterans are improved mental health symptoms, better finances, and better self-esteem (Bond et al., 2001). The specific relationship between employment and recovery from SMI in individuals has been examined (Drake et al., 2001; Bond et al., 2001; Modini et al., 2016). Previous research has not examined the correlation between recovery from SMI and employment, specifically in a population of veterans with SMI. The current study examines the relationship between recovery and employment of veterans with SMI, using the Recovery Assessment Scale (RAS) as a measure of recovery. A logistic regression analysis yielded that no relationship was found between recovery and employment status. Results of this study suggest there may be other factors affecting the relationship between these two factors. Moreover, there is the possibility that there is no relationship between recovery and employment.
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Title: HUMAN TRAFFICKING AND THE INTERNET: EDUCATING OUR COMMUNITY OF THE GROWING PANDEMIC
Creator: Ali, Md
Date: 2020
Description: Human trafficking is a growing pandemic with many traffickers utilizing both the surface web and dark web to recruit and sell victims of human...
Show moreHuman trafficking is a growing pandemic with many traffickers utilizing both the surface web and dark web to recruit and sell victims of human trafficking. We will explore different cases regarding human trafficking as well as how traffickers are uti- lizing technology to conduct their criminal activities. We will be going over different research studies that went over new social engineering methods that technology has introduced into the world of human trafficking and coming to a statistical analysis on preventive measures to be aware of. With increasing advancements in encryption methods and communication the ease of this crime has been committed from one’s own bedroom. This thesis will be answering the question on how to minimize or remedy this atrocious criminal activity from society by analyzing all the recommendations from each study and finding possible solutions to avoid being a victim of human trafficking.
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Title: Applying Statistical Methods to Air Quality and Asthma Data in Chicago Homes
Creator: Abromitis, Kari
Date: 2020
Description: This thesis investigates one years’ worth of indoor and outdoor air pollution data collected from Chicago area homes in relation to results...
Show moreThis thesis investigates one years’ worth of indoor and outdoor air pollution data collected from Chicago area homes in relation to results from monthly asthma surveys taken by the residents of those homes. This examination involves the processing and calibration of this large dataset, basic statistical analysis, and analysis of asthma as related to variation of air pollution and air pollution resulting from nearby transportation sources. The data was collected as a part of the Breathe Easy project, which was funded by the HUD and involved IIT and Elevate Energy, a Chicago-based economic development organization that promotes building equality through climate action. The majority of the data processing and analysis were performed using Python and it is intended for continued use during the ongoing Breathe Easy project. The basic statistical analysis of this data led to initial investigations of how the variability of pollutants on a daily basis triggered asthma severity and symptoms. There were limited relationships observed between asthma symptoms and pollutant variability, and it was found to not be as important as overall pollutant levels. A second investigation was pursued to examine how the proximity to transportation, including Metra trains, freight trains, elevated rail trains, highways, bus lines, and busy roads, affected indoor and outdoor pollution levels at each home, as well as concurrent asthma outcomes. Similar to previous research, there was some relation for transportation closeness, particularly for highways and Metra trains, and pollution emitted that effects the health of nearby residents. In addition, homes that had greater air infiltration (via envelope airtightness measurements) had elevated levels of particulate matter – the pollutant most associated with transportation proximity. This thesis provides a basis for further investigations in this ongoing project and for similar asthma and air quality relationship studies.
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Title: 3D reconstruction of lake surface using camera and lidar sensor fusion
Creator: Khan, Shahrukh
Date: 2020
Description: Global Navigation Satellite System Reflectometry (GNSS-R) relies upon detecting the GNSS signals reflected off a surface and then analyzing...
Show moreGlobal Navigation Satellite System Reflectometry (GNSS-R) relies upon detecting the GNSS signals reflected off a surface and then analyzing the reflected signal to obtain surface characteristics. GNSS-R has become one of the many additional applications of the readily available GNSS signals, alongside more traditional remote sensing of ionospheric monitoring, beyond the intended GNSS purposes of providing position, navigation, and timing estimation. In previous work, GPS signals reflected off Lake Michigan in Chicago have been collected using a specially designed portable sensor suite. The data collected is then analyzed to differentiate between surface ice and water conditions, as well as obtain other characteristic information such as surface reflectivity. The goal is to provide a way for remote sensing of seasonal ice formation beyond just satellite imagery which can be affected by cloud cover. To confirm the validity of the GNSS-R results there needs to be a separate reference against which to compare. This work demonstrates the sensor fusion between camera and lidar to reconstruct the lake surface, to provide that truth reference for comparison against the results of the GPS reflectometry signal processing. For this setup, the camera provides visual information about the lake surface, while the lidar provides distance information with respect to the sensor suite. Combining the data from the two sensors allows backward projection of the camera image to reconstruct the lake surface and its features. The backward projection relies upon knowledge of the camera's intrinsic properties alongside distance information of the features captured by the camera. Each pixel of the camera image is then transformed to its 3D position relative to the sensor system. This produces a 3D map of the lake surface, as captured by the sensors. The estimated point at which the GPS signal reflects off the surface, the specular point, is calculated by the satellite position at the time of interest and the receiver location. This point is then mapped onto the reconstructed surface to identify the exact location where the signal reflected and compare the surface visually to the results from the signal analysis.Time-varying camera-lidar-specular-point maps of the data campaigns conducted for this project are created for comparison with the GPS signal analysis. Multiple data campaigns were performed during which the Lake Michigan surface had surface ice, water or a mixture of the two. The lake surface is reconstructed for different timestamps, using the appropriate image frame and lidar frame. Combining chronologically, the changes in the lake surface can then be observed along with the movement of the specular point, due to the movement of the GPS satellites. Any satellites passing over a boundary between water and ice on the lake surface are identified and time stamped, to then be compared to the GPS signal analysis results.
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Title: Gaussian Process Assisted Active Learning of Physical Laws
Creator: Chen, Jiuhai
Date: 2020
Description: In many areas of science and engineering, discovering the governing differential equations from the noisy experimental data is an essential...
Show moreIn many areas of science and engineering, discovering the governing differential equations from the noisy experimental data is an essential challenge. It is also a critical step in understanding the physical phenomena and prediction of the future behaviors of the systems. However, in many cases, it is expensive or time-consuming to collect experimental data. This article provides an active learning approach to estimate the unknown differential equations accurately with reduced experimental data size. We propose an adaptive design criterion combining the D-optimality and the maximin space-filling criterion. The D-optimality involves the unknown solution of the differential equations and derivatives of the solution. Gaussian process models are estimated using the available experimental data and used as surrogates of these unknown solution functions. The derivatives of the estimated Gaussian process models are derived and used to substitute the derivatives of the solution. Variable-selection-based regression methods are used to learn the differential equations from the experimental data. The proposed active learning approach is entirely data-driven and requires no tuning parameters. Through three case studies, we demonstrate the proposed approach outperforms the standard randomized design in terms of model accuracy and data economy.
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Title: THE MODERATING AND MEDIATING ROLE OF SELF-REPORTED FAMILY ACCOMMODATION ON THE RELATION BETWEEN OBSESSIVE-COMPULSIVE SYMPTOMS AND RELATIONSHIP SATISFACTION IN AN ADULT, CLINICAL SAMPLE OF INDIVIDUALS IN ROMANTIC RELATIONSHIPS
Creator: De Leonardis, Andrew J
Date: 2020
Description: Severity of obsessive-compulsive symptoms (OCS) is associated with treatment resistance, and in an interpersonal context, is associated with...
Show moreSeverity of obsessive-compulsive symptoms (OCS) is associated with treatment resistance, and in an interpersonal context, is associated with increased relationship distress and decreased relationship satisfaction. In addition, caregivers for those with clinical levels of OCS often engage in family accommodation (FA) behaviors that serve as an extension of the OCD patient’s compulsive behavior. However, the literature on the interchange of OCS, FA, and relationship satisfaction is limited in scope because it focuses mainly on the perspective of the caregiver or partner of the individual with OCD. The current study aims to address this limitation by examining OCS, FA, and relationship satisfaction variables from the perspective of the individual with OCD. Participants included 78 adults with self-reported OCD who were recruited in the US through clinics and clinicians specializing in OCD treatment, as well as from OCD non-profit organizations to target non-treatment-seeking participants. After controlling for demographic variables, results indicated the following: (1) a significant positive association between OCS and FA, (2) a significant negative association between OCS and relationship satisfaction, and (3) a lack of an interaction between FA and OCS when predicting relationship satisfaction. However, the third result was trending towards significance and may be statistically underpowered. Exploratory analyses found FA to be a partial mediator of the association of OCS and relationship satisfaction. The findings support current trends in the research literature as well as contradict extant research on the associations between OCS, FA, and relationship satisfaction. Additionally, findings continue to show the importance of addressing family accommodation in treatment of individuals with OCD.
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Title: Evaluation of Salmonella Proliferation on Alfalfa Sprouts during Storage at Different Temperatures
Creator: Lin, Chih Tso
Date: 2020
Description: Sprouts, a low-calorie vegetable rich in nutrition, have been a popular ingredient in many meals in the USA. They are grown either at...
Show moreSprouts, a low-calorie vegetable rich in nutrition, have been a popular ingredient in many meals in the USA. They are grown either at commercial sprout farms or at home and served raw or lightly cooked. However, sprouts are also known as a source of foodborne illness outbreaks. FDA Food Code identifies raw sprouts as a time/temperature control for safety food. However, little information is known about the growth profile of foodborne pathogens in sprouts stored at different temperatures. This study aimed at evaluating the proliferation of Salmonella in alfalfa sprouts during storage at 4, 10, and 25℃ under two different contamination routes: 1) sprouts that were inoculated with Salmonella after harvest and 2) sprouts that were grown from contaminated seeds. Alfalfa sprouts grown from uninoculated seeds and harvested after 5 days of sprouting were divided into 25-g portions. Each portion was inoculated with a cocktail of five Salmonella serovars at levels of 10^1, 10^3 or 10^5 CFU/g prior to storage at 4, 10, or 25℃. Alternatively, sprouts grown for five days from seeds spiked with 1% of seeds previously inoculated with the Salmonella cocktail were divided into 25-g portions and stored at 4, 10, or 25℃. At defined time points (Days 0, 2, 4, 7, 14, and 21), levels of Salmonella and background microflora in stored sprouts were determined by plate count. Alfalfa sprouts appeared fresh during the 21 days of storage at 4 or 10℃ but started to show signs of spoilage after 4 days of storage at 25℃. The total plate counts maintained at a level above 9 log CFU/g throughout 21 d of storage at 4 and 10℃ or during the first 7 d of storage at 25℃. Storing sprouts at 4 or 10℃ could inhibit the proliferation of Salmonella. After 21 d of storage, the Salmonella counts in inoculated sprouts decreased slightly, by 0.88 or 0.93 log units, respectively. For sprouts stored at 25℃, the Salmonella growth profile differed depending on the route of contamination and the level of Salmonella at the start of storage. In sprouts inoculated at levels of 1.41, 2.83, and 4.75 log CFU/g, the Salmonella counts increased to 6.62, 6.86, and 6.68 log units, respectively, during the first 4-7 days of storage. For alfalfa sprouts grown from contaminated seeds, the Salmonella counts remained at a level similar to that in the harvested sprouts (8.16 log CFU/g) during the first 7 d. Results from this study further the understanding of pathogen growth in sprouts and will aid in the development of guidelines for proper storage of sprouts.
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Title: Ultraviolet photo-chemical degradation of polyethylene terephthalate for use as an alternative recycling method
Creator: Smith, Andrew Thomas
Date: 2020
Description: Consumer plastics are a deeply integrated part of the modern world. Their inherent properties which make them cheap, durable, moldable, and...
Show moreConsumer plastics are a deeply integrated part of the modern world. Their inherent properties which make them cheap, durable, moldable, and versatile have caused plastics to be used in many consumer products available for market. However, these same properties have made them a detriment to local and global environments. plastic has begun accumulating in the world’s waterways and oceans, leading to severe ecological consequences. Polyethylene terephthalate (PET) is one of the most pervasive consumer plastic, and a large contributor to the amount of waste. Because of its prevalence in the market, PET has been the focus of research into its recycling and reuse. However, all methods face issues of profitability due to operation and equipment costs, preventing widespread recycling of plastic waste. This leaves the door open to explore other processes of plastic recycling.In this study, ultraviolet photo-chemical degradation of PET was explored as an alternate route to plastic recycling. Ultraviolet irradiation has long been known to depolymerize PET plastic products, but has not been studied in order to enhance these effects. This method has the potential to reduce operation and equipment costs associated with traditional chemical recycling methods by carrying out depolymerization in the solid state. By harnessing this process, PET could be used to degrade material down to a state usable in in other, higher value products. An irradiation chamber was built as a preliminary prototype. This chamber used light of a specific ultraviolet wavelength determined from the absorbance spectrum of PET samples. This allowed the irradiation to be safer, while still maintaining absorption.Ultraviolet degradation of PET was first examined using infrared, contact angle, and fluorescence analysis, and birefringence observation to analyze the chemical and surface effects of irradiation. The results were used to understand the complex mechanisms behind the photo-chemical degradation process. Results were then discussed alongside similar experiments performed in the literature for a deeper understanding of the underlying mechanism.The molecular weight of exposed bottle samples was evaluated using both viscosity and dynamic light scattering methods. This information is key, as it is the main metric that determines the success of the process. In addition, the ultraviolet absorbance of the sample was analyzed along with the principles of Beer’s law. This yielded quantitative analysis on the effect of thickness of the sample, the degradation rate, and the quantum yield of the process.Finally, building upon the information gathered in the study, two key process modifications are made. Thinner samples are first produced, and receive irradiation on both surfaces. The degradation of the modified process was compared to that of previous results on the basis of molecular weight reduction, reaction rate and quantum yield. Using these results, conclusions were drawn about using ultraviolet photo-chemical degradation as a recycling process.
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Title: Developing Leader Identity via Structured Reflection
Creator: Standish, Melanie P.
Date: 2020
Description: As leader identity research in the context of leader development continues to expand, it is important to understand the mechanisms through...
Show moreAs leader identity research in the context of leader development continues to expand, it is important to understand the mechanisms through which leader identity becomes more central to one’s self concept. Structured leadership reflection is proposed to positively impact leader development but has not been experimentally manipulated to understand what its impact is on leader identity change. In this study, 90 participants were assigned into one of three reflection conditions and were asked to respond to reflection prompts over the course of four days. Participants were divided into the control condition, the reflecting on others as leaders condition, or the reflecting on oneself as a leader condition. Results showed no significant differences between reflection groups and their impact on leader identity change. Though our results do not provide support for the use of structured reflection to elicit leader identity development, we suggest future research should further study structured self-reflection over a longer period of time.
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Title: GROWTH KINETICS OF LISTERIA MONOCYTOGENES DURING REHYDRATION OF DEHYDRATED PLANT FOODS AND SUBSEQUENT STORAGE
Creator: Wu, Zihui
Date: 2020
Description: Dehydrated plant foods do not support the growth of pathogenic bacteria. However, once rehydrated, the high-water activity and neutral pH of...
Show moreDehydrated plant foods do not support the growth of pathogenic bacteria. However, once rehydrated, the high-water activity and neutral pH of these foods may support the growth of pathogens, such as L. monocytogenes, during storage. The goal of this study was to examine the growth kinetics of L. monocytogenes during 5, 10, and 25°C storage on potatoes, carrots, and onions after rehydration with 5 or 25°C water. Fresh plant foods were dehydrated at 140°F (60°C) for 24 h. A 4-strain rifampicin-resistant L. monocytogenes cocktail was inoculated onto dehydrated plant foods at 4 log CFU/g and dried for 24 h. Plant foods were rehydrated in 4-volumes of 5 or 25°C water for 24 h. At various timepoints during rehydration, 30 g of sample was removed and drained for 10 min. Samples were homogenized 1:10 with BLEB and the homogenate was plated onto BHIRif for enumeration. After rehydration, samples were drained and portioned into deli-style containers for storage at 5, 10, and 25°C and L. monocytogenes was enumerated at 1, 3, 5, and 7 d. Triplicate samples were assessed at each timepoint and three independent trials were conducted. Growth rates were determined using DMFit and data were statistically analyzed using Student t-test (α=0.05). Overall, the growth rates of L. monocytogenes during storage of potatoes and carrots were higher when rehydrated with 5°C water compared to 25°C water. The highest growth rate on potatoes was 3.51±0.43 log CUF/g per d with 5°C water rehydration and 25°C storage, resulting in a 1 log CFU/g increase in 0.29 d (7.0 h). When rehydrated with 25°C water and 25°C storage, the growth rate was significantly lower at 1.03±0.01 log CFU/g per d. The highest growth rate of L. monocytogenes on carrots was 0.68±0.07 log CUF/g per day when rehydrated with 5°C water and 10°C storage, resulting in a 1 log CFU/g increase in 1.47 d (35.3 h). For onion, L. monocytogenes was below the level of enumeration during storage at 5°C for both water rehydration temperatures and also for 10°C storage with 5°C water rehydration. The highest growth rate was 0.46±0.11 log CFU/g per d, resulting in a 1 log CFU/g increase in 2.17 d. The results of this study can aid in determining appropriate time and temperature control for safety for dehydrated potatoes, carrots and onions during rehydration and subsequent storage.
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