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Deconstructing “Sophistication-Maturity”: A Survey of Judges
No full textAlthough developmental research and the justice system both recognize that young offenders are fundamentally different from adult offenders, judges have little empirical guidance as to how characteristics of justice-involved youth such as maturity should be measured and factored into judicial decisions. This study investigated how juvenile court judges weigh factors that could influence the construct of maturity when making decisions regarding juveniles. Participating judges (N = 47) viewed one of eight vignettes about a hypothetical juvenile, which varied in regard to psychosocial maturity, physical maturity, and severity of offense. Participants then indicated whether they would transfer the juvenile to adult criminal court, and rated the degree to which the juvenile needed punishment and rehabilitation. Results showed that offense severity significantly influenced judges’ transfer decisions, while information about the juvenile’s psychosocial maturity and physical appearance did not. The potential implications of these findings in the context of the juvenile justice system are discussed.M.S., Psychology -- Drexel University, 201
Fluid-Structure Interaction Analysis of Implantable Axial Flow Blood Pump Impeller for Fontan Patients
No full textInfants who are born with cardiac defects that are characterized as a single ventricle physiology face numerous physiological complications, such as early-onset congestive heart failure, thrombosis, arrhythmias, and protein losing enteropathy. Clinical treatment and management costs for this cohort of patients exceed $1 billion/year. It is theorized a systemic pressure boost of 1-5mmHg is sufficient to alleviate many of these complications, and there is a growing interest in the use of blood pumps as a bridge therapy to heart transplantation. Currently available blood pumps have limited use in these patients because they are large and designed for adults. A major constraint of current pumps is the diameter, rigid fixed-blade designs and off-design operation due to the rigid designs, which leads to irregular flow patterns, inefficient performance, and blood damage. The presented study investigates the use of flexible blade designs to begin working toward the design of a minimally invasive blood pump with blade pitch adjusting capabilities. Using one-way fluid-structure interaction (FSI) computational studies, the implications of blade deformation on pump performance and blood damage was investigated for flexible impellers made from biocompatible materials such as nitinol, polyurethane, and silicone. It was found that rotational speed is the largest determinant of impeller deformation and the maximum deformation occurred at the blade trailing edge. The models predicted the maximum impeller deformation for nitinol to be 40nm, Bionate 80A polyurethane to be 106um, and silicone to be 2.8 mm, all occurring at 9000 RPM from 15 kPa of fluid pressure on the trailing edge of the impeller blade. The effects of silicone deformation on pump performance was significant, particularly at rotational speeds above 5000 RPM where a decrease in pressure generation of more than 10% was observed for all rotational speeds. Despite the loss, pressure generation still exceeded the level required to alleviate Fontan complications and with proper characterization the loss could be overcome through optimization of operating conditions. The estimated blood damage observed for all materials tested at all operational conditions remained below a level acceptable for blood pumps. The contributing effect of significant impeller deformation on blood damage was inconsistent and requires additional investigation because deformation did reduce blood damage metrics in some circumstances, something that could be leveraged in the future with further study. These results support the continued development of an axial-flow, mechanical assist device as a new clinical therapeutic option for patients with dysfunctional or failing single ventricle physiology.M.S., Biomedical Science -- Drexel University, 201
Family Neurologic and Psychiatric History and the Risk of Autism Spectrum Disorder
No full textObjective: In this dissertation, we aimed to determine: 1). familial recurrence risk of autism spectrum disorder (ASD) with and without intellectual disability (ID), as well as 2). risk of these ASD subtypes associated with family history of mental and neurologic disorders. Study design: We conducted a population-based cohort study for each research aim. Index persons (IPs) through whom families were identified (n = 567,436) were non-adopted singleton births identified from the Stockholm Youth Cohort, who were born between 1984 and 2009 in Stockholm County, Sweden, could be linked to both biological parents, and had resided in Stockholm County for at least 2 years at the end of follow-up. The Multi-Generation Register was used to determine family relations for each IP up to four degrees of relatedness. Diagnoses data were ascertained from regional and national registers using International Classification of Diseases and Diagnosis and Statistical Manual of Mental Disorders codes, as well as health services records. Methods: Logistic regression with robust standard error was used to estimate the odds ratio of ASD with or without ID in IPs with relative affected vs. unaffected by ASD and other neurologic and psychiatric disorders. Heritability analysis was carried out using structural equation modeling. Results: ASD without ID was more heritable than ASD with ID, broad-sense heritability (95% confidence interval): 61.5% (35.4-88.3%) vs. 25.7% (9.0-57.0%), respectively. ASD without ID was more familial than ASD with ID. The more closely related the affected family member was, the greater the observed risk was of ASD in the IPs, especially for ASD without ID. For example, for IPs with mothers affected by ASD, the IPs' odds of ASD with and without ID increased by 10.8 and 19.6 folds, respectively, whereas for IPs with affected aunts, the odds of ASD with and without ID increased by 1.3 and 1.8 folds, respectively. As for family history of neurologic and psychiatric disorders, ASD without ID was associated with more disorders and generally more strongly compared to ASD with ID, especially for mental disorders. Family history of multiple disorders was associated with greater risk, including history of ASD, ID, attention-deficit/hyperactivity disorder, obsessive compulsive disorder, schizophrenia and other non-affective psychotic disorders, depression, bipolar and personality disorders, cerebral palsy, and epilepsy. Conclusions: Familial risk and heritability of ASD without ID is higher than that of ASD with ID. This implies that risk factors between these phenotypes differ as well. Both of ASD with and without ID variance can be explained by substantial genetic and environmental sources. Also, family history of mental and neurologic disorders is associated with ASD, and this familial risk differs by presence or absence of ID. Our findings encourage us to pursue with examining these phenotypes separately in future ASD risk research and prediction endeavors, and to extend the investigation to extended family members and possible genetic and environmental risk factors as well as their interactions.Ph.D., Epidemiology -- Drexel University, 201
Nonlinear Model Predictive Control of Processes with Incomplete State Measurements
No full textThis dissertation consists of two main parts. The first part provides a comprehensive review of the tuning guidelines that have been introduced for model predictive controllers (MPCs) since 2010. The second part deals with nonlinear control of single-input single-output processes with manipulated-input-saturation constraints, incomplete state measurements, and an unstable steady-state operating point. A nonlinear controller is proposed. It includes an input-output linearizing state feedback controller, which is also an analytical solution to a shortest prediction horizon, continuous-time MPC optimization problem. It uses a closed-loop nonlinear reduced-order state observer to estimate unmeasured state variables. As it handles input constraints optimally, it exhibits no integrator windup. Given the closed-loop stability of the control system, it guarantees zero steady-state error (offset) in the presence of constant process disturbances and process-model mismatch. Its application and performance are illustrated by applying the controller to two nonlinear chemical process examples, a chemical reactor and a bioreactor, via numerical simulations.M.S., Chemical Engineering -- Drexel University, 201
Substance Use and Misuse Among Nursing Students: A Phenomenological Study
No full textSubstance use among nurses and nursing students creates a dangerous environment for the delivery of safe and effective patient care. This qualitative study used a phenomenological research design to explore the knowledge, attitudes, and perceptions of nursing students about substance use and the factors that can influence behaviors and decisions that nursing students make with respect to using drugs and seeking help. Gatekeeping Theory (Lewin, 1947) and Deterrence Theory (Haack & Yocom, 2002) provided the framework and guidance to answer the following research questions 1) What do nursing students perceive as factors that contribute to substance use disorders among nursing students? a.) What do recent nursing student graduates perceive as factors that contribute to substance use disorders among nursing students? 2) What do lived experiences of nursing students reveal about how nursing students with substance use disorders seek help? a.) What do lived experiences of recent nursing student graduates reveal about how nursing students with substance use disorders seek help? 3) Based on the lived experiences of nursing students, what types of strategies are found to be effective in managing substance use among nursing students? a.) Based on the lived experiences of recent nursing student graduates, what types of strategies are found to be effective in managing substance use among nursing students? Findings revealed six themes: a) mental health related issues b) stressors as contributing factors to substance use and misuse, c) fears and reservations d) stigma, e) seeking help, and f) awareness. The results and conclusions became the foundation for the final recommendations focused on strategies to address contributing factors that may influence a student's decision to use drugs. The four recommendations are a) identify an administrator or faculty member as a confidential resource for seeking help b) identify nursing students at risk for developing substance use disorders, c) incorporate substance use and misuse within the nursing profession into the undergraduate curriculum, and d) develop a universal manual describing substance use policies and resources for seeking help.Ed.D., Educational Leadership and Management -- Drexel University, 201
The Successes, Challenges, and Ethics of a Virtual Project Team Implementing Learning Analytics in a California Community College Setting: A Case Study
No full textLearning analytics has emerged from a confluence of factors including expanding volumes of student data generated from learning management systems and student information systems, advanced technologies for retrieving and analyzing that data, and a desire of higher education institutions to understand more about student behavior, teaching and learning, program efficacy, and institutional effectiveness. The proliferation of student data has also created corresponding concerns about student privacy and information ethics. Meanwhile, as computer-mediated communications technologies have continuously improved, organizations increasingly use geographically disperse virtual teams for work projects. Using a thorough literature review, one-on-one interviews, a 13-item survey instrument, and document review, this study explored how members of a virtual team working in a California community college setting designed and implemented a learning analytics project while navigating student privacy concerns and the effects of working virtually. Qualitative interview data were coded and found to thematically align with the study's conceptual framework. Descriptive statistics from the survey findings are also presented. Results and interpretations from the findings illustrated how learning analytics initiatives could be made more effective and sustainable, how the design of learning analytics can potentially lead to ethical issues, and the overall positive effects of working virtually. Possibilities for future research and practical recommendations for California community colleges and other higher education leaders are offered at the conclusion of the study.M.S., Educational Leadership and Management -- Drexel University, 201
The Effects of Conflicting Messages on Project Support Staff in Matrix Structured Organizations: A Phenomenological Study
No full textProject management is a critical practice in vendor organizations, which sell the design and implementation of services or products to customer organizations. Project management scholarship identifies a range of organizational structures which may be used in vendor organizations, including strong, weak, and balanced project management structures. While strong project management structures give the project manager the most authority, balanced or weak matrix structures are often used for cost effectiveness. Within balanced and weak matrix structures, there is potential for conflict between functional and project managers over a variety of sources in the project management setting. For this phenomenological research, there was a criterion established to attract a wide audience of participants, with experience specific to the studies central question: How do front-line employees experience reporting to two managers in a matrix structure? Conflict can further be shaped by communication dynamics, where effective communication strategies should be used to set direction and resolve points of conflict. In matrix project management settings, for organizations to perform at their best, clear communication and agreement amongst organizational leaders is imperative. Unclear direction from an authority figure may weaken project management authority and coordination. In cases where communication practices do not lead to the resolution of conflict in the matrix setting, there can be a negative impact on project support staff. Project support staff may be caught in no-win situations, where the staff experience conflicting information from project managers and functional managers, but do not feel they can approach either manager to resolve the conflict. This qualitative phenomenological research is designed to study the lived experiences of project support staff in vendor organizations. Using a semi-structured interview approach to explore the experiences of project support staff, this study sought to answer the following three sub-questions: What are the contributing factors in a matrix structured organization that may cause situations that lead to performance inhibiting behaviors? How does communication between project managers and functional managers create or foster performance inhibiting situations for project support staff? How does project support staff respond to these performance inhibiting situations?Ed.D., Education -- Drexel University, 201
Modular Agent-Based Modeling of an Urban Road Network Including its Management: To Assess the Impact of Different Transportation Asset Management Decisions
No full textThe objective of this PhD research was to explore how the complex interdependencies of a dense urban environment can be simulated through a hybrid multi-layered model, integrating agents at different resolutions. The model incorporated: (1) the graph model of an existing road network within Philadelphia, recognizing the engineering and operational characteristics of various road segments within this network; (2) vehicles and drivers as mesoscopic agents, where the vehicle types, counts and behaviors were calibrated by actual data; (3) a time and use based deterioration model and repair techniques for different elements of the road network; and, (4) an owner agent making various asset management decisions for the road network leading to four distinct scenarios. The mesoscopic traffic simulator therefore simulated feedback mechanisms linking the drivers' decisions and behaviors to the roadway steward's decisions, revealing the short-term consequences of management policies. This provided a realistic understanding of the "user costs," corresponding to different decisions on maintenance and replacement scheduling. The model proved to be a low cost, modular, sociotechnical, cloud-based model of a surface transportation urban infrastructure asset management simulator. The main computational engine selected for the model was an open-source mesoscopic traffic simulator, SUMO, which can represent driver agents, routing algorithms, and traffic control systems for a road network. This traffic model was defined and calibrated with data and reports from the local municipal planning organization. The deterioration of each roadway segment was modeled as a function of time and the simulated traffic's vehicular loads. The roadways' speed limit was a function of the deterioration and as a result, over time, the roadways became less favorable to the vehicles trying to optimize their daily path. At the beginning of each year the owner-agents assess the current deterioration levels and develop a plan and schedule either maintenance or replacement activities in order to meet specific condition objectives while also satisfying real-world constraints. The long-term planning was accomplished through the use of linear programming, while the short-term yearly schedule was achieved through a custom prioritized scheduling algorithm. A total of four different scenarios were generated to observe and compare the effects of different management policies and approaches. These included a baseline Do-Nothing scenario, a scenario based on a reactive short-term yearly scheduling scheme, and two scenarios that incorporated both short-term and long-term approaches to planning and scheduling with different constraints. A computer program was written in the Python language and adapted to take advantage of elastic cloud computing processing power to integrate the different modular components in order to simulate the daily activities within the network during a five-year period. The data from the simulations were then processed, analyzed, and visualized utilizing a combination of Python and Excel. The results for all the scenarios were compared with regards to the roadways' overall and yearly condition ratings as well as user-costs. Given the relatively short run-time of the simulation in comparison to the life-span of the assets, the short-term reactive scenario performed better than the two long-term based scenarios in the overall condition of the network. However, for longer-periods of simulation we should expect changes in the resulting operational performance and cost for different scenarios. The study was successful in demonstrating the potential of integrative modeling of complex sociotechnical infrastructures, and the computational requirements for simulating entire urban regions with interdependent infrastructures.Ph.D., Civil engineering -- Drexel University, 201
Development and Manipulation of a Drosophila Model for Toxic Effects of Mutated M1 Spastin in Hereditary Spastic Paraplegia Treatment
No full textHereditary Spastic Paraplegia (HSP) is an adult-onset disease most commonly caused by mutation of SPAST, which encodes the microtubule-severing protein, Spastin. Haploinsufficiency of spastin is a widely accepted pathological hypothesis for HSP, however, this definition of HSP has yet to find a well-functioning treatment. Based on our preliminary and published data, we predict that there is an additional gain-of-function aspect to the disease. Human SPAST has two isoforms, M1 and M87, which are produced via two start-codons. Evidence suggests that mutation of the longer M1 isoform is associated with a more toxic phenotype than mutation of the shorter M87 isoform in vivo. We believe that the M1 mutant effects can provide a mechanistic basis for the disease. Using the UAS-Gal4 system we introduced human M1 or M87 bearing one of the common mutations found in human patients, C448Y, into the nervous system of Drosophila melanogaster. We began with confirming that flies containing the mutations show a significant decrease in motor function (measured by contractions, climbing and flight motor ability). The flies expressing M1-C448Y have a significant decrease in motor ability, confirming that our flies exhibit the M1-specific toxicity seen in HSP patients. Microtubule dynamics are altered in patients with Spastin mutation; therefore, we decided to focus on stabilizing microtubules by using the drug Vinblastine. We were able to recover certain aspects motor function in M1 mutant animals after vinblastine treatment, suggesting that the microtubules must be destabilized in the M1 mutation. In order to understand the morphology of this disease at the muscular level, we used the neural-muscular junction (NMJ) of larva, a well-established model. We saw that there was an increase in synaptic bouton number in M1-C448Y-expressing flies. These data suggest that targeting microtubule stabilization is an improved method of treatment from the treatment options currently available to patients with HSP.M.S., Neuroscience -- Drexel University, 201
MXene Inks for Electronics and Energy Storage
No full textFormulations of conductive ink compatible with different patterning methods provide essential avenues to fabricate low cost, flexible electronics and electrochemical devices. Modern microfabrication techniques can print material with high resolution however, they often involve multi-step processing or expensive instrumentation. This thesis focuses on the creation and characterization of MXene in water for simple solution processable inks compatible with different deposition methods and on a variety of substrates. These Ti3C2 inks can be used for a variety of deposition methods such as painting, ink-jet printing, screen printing, and writing. This work focuses on hand written MXenes of concentrations above 30 mg/mL; employed in commercially available pens for dispensing and patterning MXene sheets directly onto substrates. These pens can be used both manually and automatically, with any biaxial instrument, to write on a variety of substrates including paper, wood, and textile. Automated writing electronics and energy storage devices can be created with the Ti3C2 ink. These systems are similar to metal-based inks except they do not require a sintering step and show superior performance when compared to equivalent carbon-based inks.M.S., Materials Science and Engineering -- Drexel University, 201