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The Lasting Impacts that High School Theatre Experiences Have into Adulthood
No full textThis is a study of the lasting impacts that high school theatre participation has into adulthood. A combination of an online survey and interviews were conducted to reveal what types of experiences adults recall from their high school theatre participation. The adults who took the online survey ranged in age from the 20's-70's. I found that the majority of adults reported positive lasting impacts. Many people experienced psychological benefits such as lasting friendships, increased self-esteem, and developed a sense of belonging with their peers. Useful life skills were also noted: management skills, public speaking, and construction skills.M.S., Arts Administration -- Drexel University, 201
Malware Detection using Behavioral Whitelisting of Software
No full textThe detection of malware has been an active area of research for a long period of time. In today’s world of computing, one of the major threats come from different kinds of malware, which makes it imperative to create malware detectors that can sense the presence of malware on our systems. However, with the rapid growth of polymorphic and metamorphic malware, many such malware-detection tools fail quickly or have a high rate of false positives. Our work tackles the problem by creating benign software detectors. Our thesis is that the number of potential malware far outnumbers the number of benign software on a computer system and hence one should detect malware as anomalies in the expected behavior of benign applications instead of trying to build behavioral models for every possible type of malware.M.S., Computer Science -- Drexel University, 201
Simulation and Modeling of Electrochemical Systems with Pore-scale Analysis
No full textOne of the most important requirements for being able to integrate clean energy generation is storage through new battery technology. For example, to address the issue from intermittent energy sources such as wind and solar power vanadium redox flow batteries (VRFBs) have emerged as promising technology. Another promising technology, particularly for vehicular application, is that of lithium air batteries which boast high energy density (an order of magnitude higher than state of the art Li-ion batteries) but suffer from short cycle life. While the majority of literature covers these energy storage systems in experimental setups experimental identification for the optimal electrode microstructure is challenging, time consuming, and expensive. The primary objective of this dissertation is to apply pore-scale modeling to simulate the effect of key design parameters and operating conditions to optimize cell performance in vanadium redox flow and lithium-air batteries. The motivation behind selecting these battery systems is not only the technological advantages highlighted above but also because they span very different electrode architecture length scales (nanometers for Li-air to millimeters for flow batteries), which will enable the models developed to be utilized in many different systems beyond the specific ones studied here.Ph.D., Mechanical Engineering and Mechanics -- Drexel University, 201
Social Problem-Solving Moderates the Relationship Between Postdeployment Reintegration Difficulties and Suicide Ideation Among U.S. Veterans
No full textSuicide is a significant health concern among U.S. veterans. The Department of Veterans Affairs released a report indicating that the rate of suicide for veterans is 1.5% greater in comparison to non-veterans. The rise in suicide among veterans has shown to be associated with the transition from military to civilian life. Approximately, 25% of veterans reported difficulty after deployment in major life domains including social functioning, productivity, community involvement and self-care (Sayer, Carlson, & Fraizer, 2010). The research has demonstrated that social problem-solving (SPS) can buffer the negative effects of stressful life events and daily problems (Nezu, Nezu, & D’Zurilla, 2013). Among the population of veterans, SPS has shown to be associated with reduced distress levels and increased resilience. To date, no research has investigated the relationship between postdeployment reintegration difficulties and SPS, or how they affect suicidal behaviors. The present study aimed to examine whether SPS moderates the relationship between postdeployment reintegration difficulties and suicide ideation. A sample of 198 veterans completed an online survey that included a demographic questionnaire and the following validated self-report measures: Military to Civilian Questionnaire (M2C-Q), Social Problem- Solving Inventory-Short Form (SPSI-R:S), and Beck Scale for Suicide Ideation (BSS). As expected, postdeployment reintegration difficulties and SPS were both found to be significantly correlated with suicide ideation. Additionally, SPS was found to moderate the relationship between postdeployment reintegration difficulties and suicide ideation. In other words, when participants reported high levels of postdeployment reintegration difficulties, “effective problem solvers” experienced significantly lower levels of suicide ideation compared to “ineffective problem solvers.” These findings demonstrate the importance of adaptive social problem-solving abilities in decreasing suicidal behaviors in individuals with postdeployment reintegration difficulties and provides the preliminary rationale for utilizing Emotion Centered Problem-Solving Therapy (EC-PST) treatment approach. Future research that evaluates the efficacy of EC-PST could provide evidence for the use of this intervention in veterans experiencing reintegration difficulties at increased risk for suicide.M.S., Psychology -- Drexel University, 201
Create, Destroy, Transform: A Brain-Based Approach to Trauma Treatment
No full textThis paper describes the conceptualization and enaction of a method that sought to treat adults with histories of trauma who experienced symptoms of trauma. Research supporting the creation of this method encompassed literature surrounding neurological, arts-based, narrative, metaphorical, and relational approaches to trauma treatment. This paper directly directly aligns the art therapy directive Create, Destroy, Transform to the Expressive Therapies Continuum, the 5 R’s of neurodevelopmental trauma treatment, and a stage approach trauma treatment. Implementation of Create, Destroy, Transform revealed the potential of regulation of the dysregulated brain, effects of using art as metaphor in trauma treatment, and stages of treatment necessary for trauma resolution. This method seemed to successfully allow for individuals to express, lament, and reintegrate their traumatic experiences into their life stories, possibly resulting in trauma resolution and post-traumatic growth. Finally, recommendations for future research and suggestions for the application of this method in therapy were outlined.M.A., Art Therapy and Counseling -- Drexel University, 201
Mindfulness-Based Art Therapy With Medical Staff In Oncology
No full textTreatment administered in a medical setting can result in complications for all individuals involved in that care, including the patient directly, their caregivers, and the medical staff. In oncology settings, specifically, high rates of stress levels, burnout, and compassion fatigue are prevalent. Symptoms of these mental health experiences can lead to decreased quality of care for patients, a shortage of staff to work with patients in need of medical intervention, and poorer quality of self-care practices, if any are utilized. This purpose of this capstone thesis project was to develop a method of incorporating mindfulness-based and arts-based practices as a means of promoting workplace self-care for oncology nurses. The literature demonstrated that both mindfulness and art therapy interventions in these settings for professional staff tended to be beneficial in stress reduction and promoted the exploration of emotional regulation, support from peers, and development of a sense of self. Through my experiences as an art therapy intern at a research based hospital, I uncovered the need for the staff to receive respite time from their work in order to stay rejuvenated. I observed the importance of accessibility and awareness to self-care practices in the workplace, the value of support from coworkers, and openness to experience. The need to be flexible, adaptable to, and aware of staff needs as the art therapy facilitator proved to be vital for the success of this mindfulness and art therapy based self-care format.M.A., Art Therapy and Counseling -- Drexel University, 201
Do Juvenile Probation Officer Recommendations Mediate the Relationship Between Youth Behaviors and Supervision Review Hearing Outcomes?
No full textWhile under community-based court supervision, youths’ (non)compliant behaviors are monitored by juvenile probation officers (JPOs), who provide recommendations to the court about whether youths’ levels of supervision should be increased, decreased, or remain the same. The current study examined the extent to which JPOs’ recommendations influenced judges’ decisions at review hearings (N = 775) in a mid-Atlantic jurisdiction, and whether JPOs’ recommendations varied by youth demographic characteristics (i.e., race/ethnicity, gender, age). Binomial multilevel mediation analyses, conducted using the lme4 and mediation packages in RStudio, indicated that JPOs’ recommendations mediated the relationship between youths’ noncompliance and judges’ orders to decrease levels of supervision relative to increasing or maintaining current levels. JPOs’ recommendations did not mediate the relationship between youths’ noncompliance and judges’ orders to increase supervision levels relative to keeping youth at their current levels. Moderated multilevel mediation analyses revealed that youths’ race/ethnicity impacted the relationship between noncompliance and JPOs’ recommendations to decrease supervision relative to maintaining current levels; White youth were less likely than youth of racial minority status to receive recommendations for reductions in supervision. Youths’ age and gender did not appear to impact JPOs’ decision making. Findings suggest that JPOs’ recommendations played an important role in judges’ decision making in some, but not all, contexts and that some JPOs’ recommendations depended on youths’ race/ethnicity. Policy and practice considerations regarding consistent decision making in the context of current probation transformation efforts, as well as directions for future research (e.g., whether the nature or extent of noncompliant behaviors drive judges’ decisions), are offered.Ph.D., Psychology -- Drexel University, 201
The Optical Variability of Active Galactic Nuclei
No full textActive Galactic Nuclei (AGN) exhibit strong, rapid optical luminosity fluctuations that are often described as stochastic (exhibiting intrinsic randomness). The physical mechanisms that produce stochastic fluctuations may be studied by characterizing the correlation structure of such data in both the time domain and the frequency domain. We find evidence that AGN do not exhibit a universal optical PSD; the PSD shape (or light curve correlation structure) may be a function of fundamental AGN properties. In this work, we develop an application of continuous-time autoregressive moving average models (CARMA) to AGN optical light curves, and we discuss their relationships to more traditional techniques such as the structure function (SF) and the power spectral density (PSD). We present a study of AGN variability using the Damped Harmonic Oscillator (DHO) or CARMA(2,1) model. We estimate DHO timescales and optical variability amplitudes for 7492 objects with both SDSS (Stripe 82) r-band and CRTS V-band light curves. We employ clustering methods (t-distributed stochastic neighbor embedding) in this work to test the non-universality of AGN variability (deviations from the damped random walk; DRW or CARMA(1,0)). This approach groups together light curves with similar correlation structure as described by DHO timescales. We identify three classes of AGN variability. We find a "long memory" variability class characterized by milder variability amplitudes () and steeper SFs than DRWs. We also detect a variability class characterized by an excess of short timescale variability ( days). The onset of the excess takes the form of a secondary break in the SF/PSD at short timescales. The break timescale (CRTS light curves) is anti-correlated with bolometric luminosity ( +13.2). Finally, we identify failed DHO model-fits with characteristic timescales that are greater than the timescale detection limit of a single 8-10 year survey. We estimate that for of AGN we cannot meaningfully estimate timescales without combining decades-long surveys. We find a strong discrepancy between SDSS and CRTS light curves for the same AGNs at timescales relevant to the secondary SF break. The discrepancy calls into question the impact of sparse cadence (SDSS) and large photometric uncertainties (CRTS) on similar methods such as the SF and PSD that are used to characterize the correlation structure of stochastic data. We also explore a Kepler/K2 dataset of well-sampled ( minute cadence) light curves for spectroscopic AGN and AGN candidates. We detect instrumental systematics in K2 data that require careful error mitigation. Our investigations provide characterizations of the noise dependence on CCD channel, pixel row/column, and magnitude. We provide recommendations for continued development of processing software to rehabilitate K2 data for the study of AGN PSD shapes at short timescale as a function of physical properties (luminosity, black hole mass and Eddington ratio). The results of this investigation suggest that the optical variability of AGN specifically, at short timescales ( days), may contain the richest insights for AGN science.Ph.D., Physics -- Drexel University, 201
From Fiber Meshwork Mechanotransduction to Cartilage Tissue Engineering
No full textCells adhere to the extracellular matrix (ECM) through integrins and probe the physical properties of the matrix by applying contractile forces at integrin adhesions (known as mechanosensing). They convert this mechanical information into biochemical signaling pathways that affect activation of downstream gene transcriptions, ultimately controlling cell migration, proliferation, differentiation and apoptosis (known as mechanotransduction). In the past decade, mechanosensing and mechanotransduction have been demonstrated as a critical role in many essential biological processes such as tissue regeneration, as well as pathological processes such as cancer metastasis. This role has driven the emergence of mechanobiology as a new research field. Biomaterials have been created in effort to reveal mechanotransduction processes. Initial studies were on linear elastic two-dimensional (2D) hydrogels and established the stiffness or linear elasticity as a key parameter in mediating cell behavior. Now the field has begun to move into 3D encapsulating materials with degradability and time-dependent mechanical properties such as viscoelasticity and plasticity. However, there is also a growing realization that these simple models cannot capture the complex material properties of ECM, which consists of 3D meshwork of biopolymer fibers with diameters typically of the order of micrometers. Unlike homogenous and isotropic hydrogels, biopolymer networks show a strong nonlinear elasticity, due to entropic or non-thermal strain-stiffen or softening in response to loading. As shown by pioneering work using 2D electrospun microfiber sheets, cells sense the physical properties (ex: stiffness and topography) of the bundles of microfibers and can reorganize the microfibers. However, extending this study into 3D fiber meshwork, which better resembles the native ECM, was hindered by the technological limitation of electrospinning, as densely packed electrospun fibers present a barrier that does not allow a uniform distribution of cells in 3D. Due to the lack of 3D platform, how cells sense and respond to 3D fiber meshwork remains largely unknown. My PhD research focused on: 1. Invent a new fabrication technique that can ensure a uniform 3D cell distribution, in which fibers' diameter and alignment can be independently tuned. This platform enables a direct control of 3D fiber architecture that cells sense. 2. Study how cells sense and respond to 3D fiber meshwork (3D mechanotransduction). The above microfibers platform was used to study how spatial confinement affects 3D mechanotransduction. 3. Study how 3D microfibrous structures affects the chondrogenic differentiation of mesenchymal stem cells. The results showed that 3D, microfibrous architecture regulates chondrogenic differentiation, leading to either cartilage-like genes and matrix production, in which cells produced mainly type II collagen, or fibrocartilage-like genes and matrix production, in which cells produced mainly type I collagen. 4. Use an ex vivo model to evaluate the feasibility of applying the microfibers platform to cartilage repair. A main challenge of the current strategy for cartilage repair is the lack of optimal scaffolds for cartilage production. The integration between new cartilage and the host cartilage is another long-standing hurdle. Horse cartilages, a well-established model to resemble the human cartilages, were used for this study. The microfiber platform was used to examine which fiber architecture better promotes cartilage matrix formation. Horse chondrocytes and horse mesenchymal stem cells were used as model cells.Ph.D., Mechanical Engineering and Mechanics -- Drexel University, 201
Essays on Macroeconomics
No full textThis thesis consists of three chapters that explore different macroeconomic issues. In the first chapter, I introduce deep habit formation into an otherwise standard two-country sticky price model with local currency pricing and examine the model's ability to account for the dynamics of the real exchange rate present in the data. I show that if consumption is subject to deep habit formation, the model can match the volatility of the real exchange rate observed in the data, but falls short in generating enough persistence in line with the empirical evidence. In the second chapter, I use data from US Treasury auctions to collect information on the bid-to-cover ratio, a maturity specific proxy for the degree of excess demand in the market for US Treasury bonds. I show that the financial crisis of 2008-09 generated a significant increase in bid-to-cover for short and medium duration debt. Excess demand from private investors has thus likely imposed considerable downward pressure on these yields separate from monetary policy. Further, the notably larger observed increase in bid-to-cover for short-term debt may have contributed to short-term rates hitting the zero lower bound and point to the existence of a convenience yield within the market for US Treasuries. In addition, I find that the US Treasury issued more bonds with medium duration (2,3 and 5 years) in response to the Federal Reserve's first and third quantitative easing programs. Thus, the US Treasury may have reduced the effectiveness of these unconventional policies in lowering yields for medium duration bonds. In the third chapter (joint with Marco Airaudo), we show that the asset market segmentation model built by Chen et al. (2012) to study the effects of quantitative easing contains a unit root. The unit root introduces error in the model's linear approximation, its convergence dynamics and its determinacy properties casting uncertainty on its usefulness for policy analysis. We eliminate the unit root by assuming that agents derive utility services from government bonds. When we simulate the model, we show that it is broadly consistent with conventional theory on the transmission mechanism of quantitative easing. However, our mechanism also highlights a new channel: a negative wealth effect which may counteract some of the stimulus induced by the central bank's purchases of long-term debt.Ph.D., Economics -- Drexel University, 201