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The associations between psychosocial stress and coronary heart disease in two cohorts of U.S. women
No full textOBJECTIVE: This dissertation explores the effect of psychosocial stress on risk of coronary heart disease (CHD) and the underlying biobehavioral mechanisms between psychosocial stress and CHD in women. METHODS: Two cohort data were used: 1) Women's Health Initiative Observational Study (WHI-OS) participants aged 50-79 years (N= 80,825); 2) 5,089 adults (2,505 women and 2,584 men) without clinical cardiovascular disease, aged 45-84 years at baseline in Multi-Ethnic Study of Atherosclerosis (MESA). Job strain was constructed based on the Karasek's Job Demand-Control (JDC) model and imputed through linkage of Standard Occupational Classification codes to the Occupational Information Network. Stressful life events and social strain (WHI-OS only) were assessed via validated self-reported questionnaires. Various statistical modeling approaches were used: Cox proportional hazard models, generalized linear models, path analysis with covariance-based structure equation models. RESULTS: For WHI-OS participants with an average of 14.7 years of follow-up, high job strain was associated with 13% increased risk of CHD (HR=1.13, 95% CI:1.03,1.24). Women with the high life event scores had a 20% higher risk of CHD (HR=1.20, 95% CI: 1.09,1.31), and for women with high social strain, the CHD risk increased by 12% (HR=1.12, 95% CI: 1.04,1.22). There was a significant interaction between job strain and social strain (P value= 0.02). High job strain was associated with a 25% increased risk of CHD for women with high social strain (HR=1.25, 95% CI: 1.07,1.46) while no association between high job strain and CHD risk was found in women with low social strain. The results from MESA participants showed that extreme ongoing problems in life were associated with a 7% increase in CHD risk (AMR=1.07, 95% CI: 1.02, 1.13) while job strain was not independently associated with CHD risk. There is no interaction between gender and psychosocial stress in relation to CHD risk. Changes in CHD risks over a 2-year period were not associated with either job strain or ongoing problems in life. The results from path analysis suggested that leisure-time physical activity, alcohol consumption, hypertension, and diabetes explained more than 50% of the associations between each psychosocial stressors and CHD. CONCLUSIONS: In women, psychosocial stress in different domains has a disparate impact on CHD risks, and part of the association between psychosocial stress and CHD risks is explained by biobehavioral factors. Future work for impacting other domains of psychosocial stress and interventions emphasizing specific needs of women are needed.Ph.D., Epidemiology -- Drexel University, 201
Walk In Their Shoes: How Picture Books and Critical Literacy Instruction Can Foster Empathy in First Grade Students
Get PDFIn New Jersey and nationwide, legislative efforts require that schools refocus on teaching social emotional skills in order to meet the holistic needs of students and prevent bullying. However, with an ever-growing list of school requirements, no additional instructional time, and little guidance on how to teach social emotional skills, schools need ways to integrate social emotional skills within curriculum. One way to teach social emotional skills and literacy skills simultaneously is through read aloud experiences with picture books. Using picture books on topics such as making friends, problems at school, or topics of social injustice, teachers can address critical literacy skills and social awareness while promoting empathy development. This mixed-methods study examined empathy development in 108 first grade students before and after a four-week intervention using picture books and critical literacy instruction, including writing from the perspective of others. The research used a randomized design with control and experimental groups to measure children's empathy with a modified (Garton & Gringart, 2005) Interpersonal Reactivity Index (IRI) (Davis, 1980) before and after the intervention. Student writing was also analyzed in the intervention classrooms to identify and examine evidence of empathy. This research followed Brill's (2004) method of analyzing student writing for empathy by looking for patterns in writing and then creating categories reflective of these patterns. The analysis used t-tests to compare pre-test and post-test scores in the experimental group as well as post-test scores between the treatment and control groups. These comparisons indicate that students' empathy scores, measured by the IRI, did not increase after the intervention; there were no significant differences between the treatment and control groups. However, the writing component of the study showed that students exhibited evidence of empathy in three distinct ways. They identified empathetic and non-empathetic actions in characters from stories and in real life, they showed empathy when considering imaginary scenarios from stories--inferring characters' feelings and/or proposing actions--and they showed writer empathy for characters from stories. Taken together, quantitative and qualitative findings from this research suggest that although students showed evidence of empathy learning and engagement during the intervention, they did not fully internalize empathy by the end of the intervention. This research study suggests next steps and possible future research that could be useful to support students' continued empathy development. It could be useful for schools seeking ways to address social emotional learning and curriculum simultaneously, while designing learning experiences that meet local school cultures and needs.Ed.D., Educational Administration -- Drexel University, 201
Oxygen Tolerant and Room Temperature RAFT for Synthesizing Well-defined Polymer Architectures
No full textA reversible addition-fragmentation chain transfer (RAFT) process was developed capable of being performed at room temperature and in the presence of oxygen by initiating polymerization through an alkylborane-amine complex. This air-stable alkylborane-amine complex was chemically deblocked with carboxylic acid or isocyanate functionalities to liberate a reactive alkylborane that consumes oxygen and generates radicals to drive the RAFT process. Alkylborane initiated RAFT (AI-RAFT) was demonstrated to allow a wide range of molecular weights to be targeted while maintaining narrow molecular weight distributions. In specific conditions, rapid polymerization was possible within minutes under an ambient environment, without any prior deoxygenation, yielding moderate monomer conversion and narrow dispersity polymer. Optimal conditions for conducting AI-RAFT were investigated with propionic acid and isophorone diisocyanate revealing that carboxylic acids require a larger excess of deblocker to alkylborane to promote high monomer conversion. The deblocker functionality was also observed to have an impact on polymerization kinetics, and in some cases, to influence the dispersity and achievable molecular weight. The retention of living chain-ends was confirmed by synthesizing block copolymers using AI-RAFT derived macro-chain transfer agents, which were found to most efficiently chain-extend when synthesized using lower concentrations of alkylborane initiator. In this thesis, a chemically induced RAFT process is introduced without requirement of any thermal, photochemical, electrical, or mechanical stimulus capable of polymerizing acrylamide, acrylate, and methacrylate monomers in limited amounts of oxygen at room temperature.M.S., Materials Science and Engineering -- Drexel University, 201
Multiplex Network Analysis of Local Topology in Simulated and \textit{In Vitro} Spiking Neural Networks
No full textComplex networks are important tools for investigating interactions amongst many different types of agents. Recently, the extension of single layer networks to multilayer networks has allowed for multiple types of relationships among the same actors to be represented in a network. In this dissertation, we develop two methods for using a specific type of multilayer network, the multiplex network, to study local topology in neural networks. In the first project, we use multiplex networks to compare the local topology between a simulated structural neural network and its inferred functional networks. For the second project, we use multiplex networks to observe evidence for the self-organization of \textit{in vitro} neural networks into neural ensembles.Ph.D., Mathematics -- Drexel University, 201
Integrated Design of 3D Materials
No full textAdvanced manufacturing (AM) refers to design and manufacturing through the combination of sensing, information, computation, software, testing, and/or the use of novel materials. Although several examples on the use of AM methods to design novel 3D-architectured materials have been proposed, a critical challenge in such approaches remains the validation of simulation results as well as manufacturing procedures especially in the context of the reported variability in both properties and behavior for current AM methods. An appropriate component to benchmark design for AM is their pairing with advanced testing and characterization methods capable to provide quality assessment either in situ or in post mortem. This thesis targets, therefore, the investigation of a proof-of-concept methodology that combines computational modeling with testing methods to attempt to close the loop between digital design and final manufactured product. To demonstrate such approach, Fused Deposition Modeling (FDM), an extrusion-based process in which molten filament is deposited and rapidly solidified on a heated build plate, constructing parts in a layerwise fashion is chosen due to its widespread use. For computations, an Interface-enriched Gradient-based Finite Element Method (IGFEM) shape optimization was utilized to select the optimal shape of a designed exemplary microstructure consisting of an elliptical hole. A specific criterion for optimization was used involving the overall compliance of the 3D-printed geometry which in this case was in the form of uniaxial tension test specimens. For experimental validation, FDM produced coupons using ABS were tested and compared against the simulated microstructure. Extensions of this study in the cases of more complex microstructures consisting of several volume fractions of different types of microstructures in similar specimens, as well as compression loading specimens are reported to demonstrate the way such method could reduce design time while being validated.M.S., Mechanical Engineering and Mechanics -- Drexel University, 201
Intersectionality in the Academy: Life Histories of Caribbean Women in Higher Education Leadership
No full text"Caribbean women in higher education leadership" is an area of study which deserves significantly more attention. This study investigates the reality about the true demands of professional culture on Caribbean women with distinct cultural backgrounds and expectations - and how the expectations, demands, and mores of ethnic and professional cultures may clash. It identifies the challenges and barriers, impacting the professional and personal lives of participants; determines the impact of low diversity within leadership on professional experiences; discusses the navigation of politics in order to gain upward mobility; and outlines the nuances which create positive and negative perceptions of what is required to enter and remain within leadership in order to maintain advancement. Furthermore, it seeks to discover the strategies for professional survival, and distinguishes between strategies which create advantageous and disadvantageous career circumstances. The framework of this study is the Intersectionality Theory. The conceptual framework seeks to visually display overarching and common themes within the experience of Caribbean women at multiple levels of leadership; and to additionally identify sub-themes that can speak more directly to the convergence of multiple experiential facets. Researching the personal and professional clash of cultures, in conjunction with the existing misconceptions and notions that accompany gender and race for minority women, is paramount to increasing diversity and inclusion in leadership for Caribbean women. This area of exploration is a gap in existing research which this study takes the first steps towards filling in order to increase the social capital of Caribbean women.Ed.D., Educational Leadership and Management -- Drexel University, 201
Component Enhancement and Performance Evaluation of a Rotary Heat Exchanger Utilizing Phase-Change Material
No full textThis research focused on several aspects of the development of a dry cooled rotary heat exchanger that utilizes encapsulated phase change material (EPCM). The heat exchanger prototype was designed with the intent to offer an alternative to current air-cooled condensers (ACC's) with a more efficient dry cooling alternative. The motivation was to provide power production efficiency comparable to that of wet cooling towers while still using dry cooling technology. This is achieved by taking advantage of the high latent heat capacity of solid-liquid phase change and by using the short-term thermal storage capabilities of paraffin-based PCM to reject heat to the atmosphere at the melting temperature of the PCM. The first goal of this research was to improve upon the method by which heated water is dispersed across the EPCM. This involved updating the design of the mechanism that creates a pattern of water jets that contact the PCM, which is encapsulated within thin-walled flat HDPE tubes that are arranged as 7 layers of 15 concentric rings. The spraying device is a trapezoidal spray box that receives heated water at the top side of the box and sprays through precisely located holes aligned in a radial fashion so that they are directed to the top of the EPCM rings on the bottom plate of the box. The updated design increased the number of holes in the sprayer plate from 128 to 450, decreased the hole diameter from 1/8 in to 1/16 in, and the holes were made vertical in the plate so that the water jets exited perpendicularly from the plate. Although these changes resulted in an increased minimum allowable water flow rate from 3.9 ∙ 10-3 gpm to 7.5 ∙ 10-3 gpm, the minimum allowable water temperature decreased from 46 °C to 44 °C, which yields a lower initial temperature difference (ITD) between the atmospheric and water temperature. The second goal of this research was to develop a method of manufacturing the EPCM tubes in such a way that both improved the quality and increased the production rate of the tubes. Previous methods involved manually melting and drawing PCM through HDPE tubes by using a pneumatic hand pump. This manufacturing method created porous PCM within the HDPE tubes and thus resulted in less available PCM within the tubes to provide a thermal storage medium from the hot water to the atmosphere while the heat exchanger was operating. This porosity was evident in the ~10% decrease in usable tube length at the end of the PCM tubes after the PCM melted and solidified. New methods were introduced to decrease the porosity of the tubes, which was reflected in the lack of change in useable PCM tube length upon the melting and solidification. A concept is proposed for future manufacturing of PCM tubes that would involve the simultaneous filling of 16 HDPE tubes with PCM through the use of a vacuum chamber and this method would be ideal for manufacturing PCM tubes for the current prototype and especially for future designs that may require greater lengths of tubing. Finally, an evaluation of the coefficient of performance (COP) was conducted to evaluate and verify the heat exchanger design performance and to use as a guide in the future steps of the development of the heat exchanger. The COP was calculated to be 964 with an uncertainty of ± 286. Further analysis of the data revealed that a region of the collected data was likely inaccurate and a possible influences on the data could have been PCM leakage into the water circulation system, humidity of the surrounding air, and sensors requiring recalibration.M.S., Mechanical Engineering and Mechanics -- Drexel University, 201
The Effect of Resilience-Based Psychoeducation on College Resident Advisors
No full textDeteriorating mental health and wellness in adolescents and young adults is a significant concern, especially among those in college and university settings. Research evidence suggests that cognitive behavioral therapy approaches within resilience-based psychoeducation programs may be effective in promoting mental wellness in this demographic. A pilot pre-test/post-test study was conducted at a public university’s health and wellness center in northern New Jersey. A total of seven resident advisors participated in resilience-based psychoeducation training specifically designed for college students. Participants’ resilience and depression levels were measured before and after the resilience-based training using the Connor-Davidson Resilience Scale (CD-RISC-25) and the Center for Epidemiologic Studies Depression Scale (CES-D). Statistical analysis conducted using a Wilcoxon signed-rank test revealed no statistically significant change in depression (Z = -0.85, p = 0.93) or resilience (Z = -0.76, p = 0.45), which may be attributable to the study’s small sample size (n = 7). Nonetheless, there was no attrition from the study, and all participants stated they found benefit in the program and would utilize the learned material in their peer-to-peer interactions. Clinical significance includes an important precedent for health and wellness centers at colleges and universities across the United States. Implementation of useful resilience-based psychoeducational interventions needs further study and consideration.D.N.P., Nursing Practice -- Drexel University, 201
"Tpack: technology integration and teacher perceptions"
No full textAs one considers the impact that technology has had on society as a whole, one might also question these changes as they pertain to the teaching and learning environment. The transformative nature of educational technologies has profoundly changed pedagogical thinking and looks to revolutionize our educational system, but are teachers really utilizing these technologies to their full potential? The TPACK framework considers three distinct areas in a teacher's ability to integrate technology and improve the effectiveness of their instruction: content, the information that is to be taught; pedagogy, the way in which the content is to be taught; and the technological, the digital tool or vehicle with which the pedagogical methodology will be delivered. This study examined the ways ten teachers utilize technology in their lesson planning and classroom activities for variety and frequency. Additionally, comparisons were made between years of experience, with consideration of the amount of formal and informal technology training received. The purpose of this embedded mixed methods study is to inform and improve technology professional development for teachers. This study found that veteran participants displayed a reluctance to change, providing statements concerning investing time into new pedagogical practices when they consider their current practices to be sound. Novice participants, who as a group were more open to incorporating technology into pedagogical practices, needed to be afforded an opportunity to explore other emerging methods for technology implementation. The perceptions derived from this study concerning frequency of use, and the need for more available resources, only serve to underscore the importance of improving aspects of professional development design.Ed.D., Educational Leadership and Management -- Drexel University, 201
Using Machine Learning to Differentiate between Healthy Aging, Mild Cognitive Impairment, & Alzheimer’s Disease
No full textAlzheimer’s disease (AD) is an insidious disorder in which pathology may develop decades before outward symptoms become apparent. Identification of this disease in its earliest stages would provide the greatest opportunity for successful treatment. Current recommendations place patients in groups based primarily upon CSF -amyloid (A) levels, but the procedure to gather these data is invasive. If less intrusive methods could be identified to successfully predict which individuals are especially prone to develop AD, the benefits would be invaluable. Many studies have attempted to identify these individuals using neuroimaging methods such as MRI or PET, but very few studies have incorporated EEG data, despite research indicating its relationship with AD pathology. In this analysis, multimodal classifiers incorporating EEG, MRI, and PET data were developed and used in an attempt to differentiate between AD patients and a healthy control group, as well as MCI patients with AD A pathology and those without. Additionally, repeated-measures event-related potential (ERP) data were analyzed to directly examine changes related to AD progression.Ph.D., Psychology -- Drexel University, 201