Socioeconomic Status, Acculturation, Family Characteristics, and Health Behaviors: Testing the Reserve Capacity Model with Hispanic Adolescents

Title from PDF of title page, viewed on July 10, 2015Dissertation advisor: Kymberley K. BennettVitaIncludes bibliographic references (pages 101-126)Thesis (Ph.D.)--Department of Psychology. University of Missouri--Kansas City, 2015Research shows that socioeconomic status (SES) can impact adolescent use of alcohol and smoking. These relationships may be mediated by stress, psychosocial reserves, and negative emotions. I explored these relationships using the Reserve Capacity Model (RCM) as a theoretical foundation. The RCM suggests that individuals of low social status experience stress and must tap into tangible, intrapersonal, and interpersonal resources, often leaving these reserves depleted. Low reserves, in turn, predict the experience of negative emotions which can result in poor health outcomes. The RCM was later revised to integrate cultural constructs that can serve as stressors and resources (e.g., familism, which prioritizes the role of the family as a supportive network). The purpose of this study was to test the RCM using culturally relevant variables as mediators of relationships between SES, alcohol use, and smoking in a sample of Hispanic American adolescents. I predicted that low SES would positively predict stress (e.g., perceived discrimination and acculturative stress). Stress, then, would be negatively related to reserve capacity (i.e., familism, family cohesion, and fatalism), which, in turn, would negatively predict symptoms of depression. Then, depressive symptoms would be positively related to alcohol use and smoking. A sample of 1,386 Hispanic American adolescents completed self-report measures of these constructs across three school years. Counter to my hypotheses, baseline SES was unrelated to smoking and alcohol use at year three (controlling for baseline levels). Mediation hypotheses were partially supported. Results showed baseline SES predicted increased levels of perceived discrimination at year two, which, in turn, was significantly related to decreased familism and family cohesion also at year two. Family cohesion was significantly related to symptoms of depression at year two, which, in turn, predicted increased use of alcohol and smoking behaviors at year three. Findings suggest that low SES is associated with perceived discrimination, which negatively affects family functioning. In turn, challenges in the family seem to affect distress symptoms, which, in turn, predict alcohol use and smoking. Results imply that interventions designed to address adolescent perceptions of discrimination, or family cohesion, may positively impact rates of smoking and alcohol use among adolescentsIntroduction -- Review of literature -- Method -- Results -- Discussion -- Illustrations -- Tables -- Appendix A. Letter of support, Dr. Jennifer Unger -- Appendix B. Questionnaire constructs and question

Worksite Chemical Air Emissions and Exposures During Pipe Rehabilitation Using Cured-in-Place Pipe

Cured-in-place pipe (CIPP) is the most popular water pipe rehabilitation technology in the U.S. In our study, materials emitted from the CIPP worksites were condensed and characterized in Indiana and California, and results showed that common assumptions about worksite safety were proven incorrect. In this session we share field observations and lessons learned, and provide a list of recommended construction practices to minimize risks to workers, the public, and the environment

The Efficacy of Propensity Score Matching in Bias Reduction with Limited Sample Sizes

The current literature on propensity score matching is missing imperative information for educational researchers regarding the practical implications of utilizing this method with limited sample sizes. The purpose of this study was to evaluate the effectiveness of propensity score matching when limited by sample sizes of 500,400, 300, and 200 as determined by a reduction in bias using both real and simulated data. Further effort was made to determine the optimal selection of covariates and caliper width with these limited sample sizes. Participants were selected without replacement and matched one-to-one using the nearest neighbor technique in the MatchIt package in the R software program. Contrary to the hypothesis that with reduction in sample size the balance improvement would drop below what is considered effective bias reduction, the reduction in bias was greater than 96.77% for all conditions of sample size and caliper width. A Monte Carlo simulation was created based on the real dataset to assess covariate selection with the same limitations in sample size and a set caliper width of 0.6. For all replications, the mean balance improvement was best for the covariate relationship magnitude strong_none (strong relationship to DV_no relationship to treatment) and worst for the relationship mod_strong (moderate relationship to DV_strong relationship to treatment). Only the covariate relationship strong_none was able to be deemed effective matching for all sample sizes. Findings suggest that propensity score matching can be effective at reducing bias with sample sizes as small as 200 and caliper widths as wide as 0.6. Ideal covariates are those that are strongly related to the outcome variable and only weakly or moderately related to treatment when sample sizes are limited. Keywords: Propensity Score Matching, Sample Size, MatchI

Processing and Characterization of Poly(vinyl alcohol) Compatibilized Cellulose Nanocrystals/Ethylene Vinyl Alcohol Copolymer Nanocomposites

Ethylene vinyl alcohol (EVOH) copolymer films are commonly used in food packaging due to their excellent oxygen barrier properties and melt processability. A drawback to EVOH is the lower water barrier properties, which could degrade food quality, so EVOH is often combined with other layers of polymers. The addition of cellulose nanocrystals (CNC) has been reported to improve the gas barrier and mechanical properties for other polymers. This study will focus on using CNC to improve the water barrier properties of EVOH. Since CNC is water dispersible, but EVOH is not soluble in water, poly(vinyl alcohol) (PVA) was used as a compatibilizer to improve the mixing of CNC within EVOH. Solution casting was used to mix CNC and PVA together by dissolving both in water, then making a solid film by evaporating the water. Melt processing was used to melt the CNC/PVA film with EVOH and forming the nanocomposite into a thin film. Gas barrier and mechanical properties, such as tensile strength, were examined as a function of weight percent of PVA used in each nanocomposite film. Compatibility between PVA and EVOH was determined by examining the thermal properties using differential scanning calorimetry (DSC) analysis, and degradation behavior was determined using thermogravimetric analysis (TGA). It is expected that the addition of compatibilizer, PVA, will improve these properties by making a more even mixture of CNC within the EVOH polymer matrix

Investigation of Aluminum Foams and Graphite Fillers for Improving the Thermal Conductivity of Paraffin Wax-based Phase Change Materials

Passive thermal management with phase change materials (PCMs) has become the one of the most promising methods to cool cell phone processors due to the relatively simple implementation and profound impact on processor temperatures. Enhancing the thermal properties of conventional PCMs, mainly thermal conductivity and latent heat storage, allows for an overall improved thermal management system. This study aims to improve the thermal conductivity of paraffin wax (a typical commercial PCM) by the introduction of an expanded graphite (EG) filler to form a paraffin wax composite, and then infiltration of the EG/paraffin composite into an aluminum foam matrix. The thermal conductivity of the EG/paraffin composites increases respectively to the percentage by volume of expanded graphite. While the thermal conductivity increased, there is some negative impact on latent heat storage compared to pure paraffin wax. The pore size of the aluminum foam matrixes also has a profound impact on both thermal conductivity and latent heat storage of the overall system. These results will allow for improvements in cooling techniques incorporated within cell phones and other mobile devices, allowing for future development of their processors (higher computational power), prolonged reliability, and longer anticipated life cycles

Membrane Pre-treatment Using Chemical Disinfectants in Halide Impaired Waters

The use of membrane filtration processes for desalination, water reuse, and water reclamation techniques are becoming more prevalent given freshwater shortages. However, the treatment of these waters is challenging because of the membranes used in these processes. During nanofiltration and reverse osmosis the membranes undergo biofouling. Reverse osmosis and nanofiltration are high-pressure membrane filtration techniques that treat seawater, brackish waters, and industrial wastewaters. Because of the biofouling, the polyamide thin film needs to be pretreated with chlorine (HOCl/ OCl-) as a disinfectant, but this damages the polyamide membrane. When the free chlorine is in the presence of halide-impaired waters, it changes the chemistry of the membrane thus continuing to damage it. In order to find how halide concentration and other water quality parameters affect nanofiltration and reverse osmosis, this project requires liquid chromatography and mass spectrometry method to analyze different aromatic amine compounds (e.g. benzanilide) with similar structures to the polyamide membrane. The LC/MS is optimized in order to find the limits of detection for each of the compounds. The chlorination reactions are done to quantify how much these compounds react in the presence of free chlorine. Future research with regards to this includes kinetic measurements of compound degradation and by-product formation to see how these compounds are affected by free chlorine over time

Behavior of Poly electrolyte Gels in Concentrated Solutions of Highly Soluble Salts

Ionic hydrogels are an abundant class of materials with applications ranging from drug delivery devices to high performance concrete to baby diapers. A more thorough understanding of interactions between poly electrolyte networks and ionic solutes is critical as these materials are further tailored for performance applications in highly targeted ionic environments. In this work, we seek to develop structure-property relationships between polyelectrolyte gels and environments containing high concentrations of multivalent ions. Specifically, this work seeks to elucidate the causes behind differences in hydrogel response to divalent ions of main group metals versus transition metals. PANa-co-PAM hydrogels containing low and high fractions of ionic groups are investigated in solutions of DI water, NaCl, CaCl2, and CuSO4 at concentrations ranging from 5 to 100 mM in order to understand 1) the transient or permanent nature of crosslinks produced in these networks by divalent counter-ions, 2) the role of polymer ionic content in these interactions, and 3) how these interactions scale with salt concentration. Gravimetric swelling and mechanical compression testing are employed to characterize water and salt-swollen hydrogels in order to develop guiding principles to control and manipulate material properties through polymer-counter-ion interactions. The work presented here confirms the formation of permanent crosslinks by transition metal ions, offers explanation for the behavioral discrepancy observed between ionic hydrogels and main group versus transition metal ions, and illustrates how such hydrogel properties scale with counter-ion concentration

Contaminant Release from Storm Water Culvert Rehabilitation Technologies: Understanding Implications to the Environment and Long-Term Material Integrity

Millions of miles of existing U.S. storm water culverts are critical for roadway safety but much of this infrastructure requires repair. State departments of transportation (DOT) are increasingly choosing to rehabilitate culverts with spray-on and cured-in-place pipe (CIPP) lining processes. These culvert lining practices involve the manufacture of a new plastic liner inside a damaged culvert. DOTs are selecting these outdoor plastic manufacturing methods partly to avoid open-trench excavation, which can cause traffic disruption and work zone traffic safety issues. This study was conducted to better understand current knowledge about culvert lining caused environmental contamination, final product quality, and recommend improved construction specifications, project oversight, and testing requirements to limit undesirable consequences. Literature reviews, a survey of construction specifications and special provisions for 32 transportation agencies, as well as field- and bench-scale testing for CIPP projects in California, New York, and Virginia, were completed. During this project, the safety of workers, transportation agency employees, and the general public at lining installation sites, was raised as a concern by state and federal agencies. Due to previously unreported hazards which were encountered at multiple CIPP field sites, the provision of worksite safety recommendations for DOTs was added to this study. Recommendations are provided for spray-on lining and CIPP lining culvert repair projects that can (1) limit environmental contamination, (2) improve worksite safety, and (3) aid DOTs in better understanding the quality of their new liners

Hyperpolarized Long-T1 Silicon Nanoparticles for Magnetic Resonance Imaging

Silicon nanoparticles are experimentally investigated as a potential hyperpolarized, targetable MRI imaging agent. Nuclear T_1 times at room temperature for a variety of Si nanoparticles are found to be remarkably long (10^2 to 10^4 s) - roughly consistent with predictions of a core-shell diffusion model - allowing them to be transported, administered and imaged on practical time scales without significant loss of polarization. We also report surface functionalization of Si nanoparticles, comparable to approaches used in other biologically targeted nanoparticle systems.Comment: supporting material here: http://marcuslab.harvard.edu/Aptekar_hyper1_sup.pd

Ultra-Fast Oleophobic-Hydrophilic Switching Surfaces for Anti-Fogging, Self-Cleaning, and Oil-Water Separation

Smooth copolymer–fluorosurfactant complex film surfaces are found to exhibit fast oleophobic–hydrophilic switching behavior. Equilibration of the high oil contact angle (hexadecane = 80°) and low water contact angle (110°), which, when combined with the inherent ultrafast switching speed, yields oil–water mixture separation efficiencies exceeding 98%