Estimating the prevalence rate of a disease is crucial for controlling its spread, and for planning of healthcare services. Due to limited testing budgets and resources, prevalence estimation typically entails pooled, or group, testing where specimens (e.g., blood, urine, tissue swabs) from a number of subjects are combined into a testing pool, which is then tested via a single test. Testing outcomes from multiple pools are analyzed so as to assess the prevalence of the disease. The accuracy of prevalence estimation relies on the testing pool design, i.e., the number of pools to test and the pool sizes (the number of specimens to combine in a pool). Determining an optimal pool design for prevalence estimation can be challenging, as it requires prior information on the current status of the disease, which can be highly unreliable, or simply unavailable, especially for emerging and/or seasonal diseases. We develop and study frameworks for prevalence estimation, under highly unreliable prior information on the disease and limited testing budgets. Embedded into each estimation framework is an optimization model that determines the optimal testing pool design, considering the trade-off between testing cost and estimation accuracy. We establish important structural properties of optimal testing pool designs in various settings, and develop efficient and exact algorithms. Our numerous case studies, ranging from prevalence estimation of the human immunodeficiency virus (HIV) in various parts of Africa, to prevalence estimation of diseases in plants and insects, including the Tomato Spotted Wilt virus in thrips and West Nile virus in mosquitoes, indicate that the proposed estimation methods substantially outperform current approaches developed in the literature, and produce robust testing pool designs that can hedge against the uncertainty in model inputs.Our research findings indicate that the proposed prevalence estimation frameworks are capable of producing accurate prevalence estimates, and are highly desirable, especially for emerging and/or seasonal diseases under limited testing budgets. / Doctor of Philosophy / Accurately estimating the proportion of a population that has a disease, i.e., the disease prevalence rate, is crucial for controlling its spread, and for planning of healthcare services, such as disease prevention, screening, and treatment. Due to limited testing budgets and resources, prevalence estimation typically entails pooled, or group, testing where biological specimens (e.g., blood, urine, tissue swabs) from a number of subjects are combined into a testing pool, which is then tested via a single test. Testing results from the testing pools are analyzed so as to assess the prevalence of the disease. The accuracy of prevalence estimation relies on the testing pool design, i.e., the number of pools to test and the pool sizes (the number of specimens to combine in a pool). Determining an optimal pool design for prevalence estimation, e.g., the pool design that minimizes the estimation error, can be challenging, as it requires information on the current status of the disease prior to testing, which can be highly unreliable, or simply unavailable, especially for emerging and/or seasonal diseases. Examples of such diseases include, but are not limited to, Zika virus, West Nile virus, and Lyme disease. We develop and study frameworks for prevalence estimation, under highly unreliable prior information on the disease and limited testing budgets. Embedded into each estimation framework is an optimization model that determines the optimal testing pool design, considering the trade-off between testing cost and estimation accuracy. We establish important structural properties of optimal testing pool designs in various settings, and develop efficient and exact optimization algorithms. Our numerous case studies, ranging from prevalence estimation of the human immunodeficiency virus (HIV) in various parts of Africa, to prevalence estimation of diseases in plants and insects, including the Tomato Spotted Wilt virus in thrips and West Nile virus in mosquitoes, indicate that the proposed estimation methods substantially outperform current approaches developed in the literature, and produce robust testing pool designs that can hedge against the uncertainty in model input parameters. Our research findings indicate that the proposed prevalence estimation frameworks are capable of producing accurate prevalence estimates, and are highly desirable, especially for emerging and/or seasonal diseases under limited testing budgets.

The use of graphical processing units (GPUs) for autonomous robots has grown recently due to their efficiency and suitability for data intensive computation. However, the current embedded GPU platforms may lack sufficient real-time capabilities for safety-critical autonomous systems. The GPU driver provides little to no control over the execution of the computational kernels and does not allow multiple kernels to execute concurrently for integrated GPUs. With the development of modern embedded platforms with integrated GPU, many embedded applications are accelerated using GPU. These applications are very computationally intensive, and they often have different criticality levels. In this thesis, we provide a software-based approach to schedule the real-world robotics application with two different scheduling policies: Fixed Priority FIFO Scheduling and Earliest Deadline First Scheduling. We implement several commonly used applications in autonomous mobile robots, such as Path Planning, Object Detection, and Depth Estimation, and improve the response time of these applications. We test our framework on NVIDIA AGX Xavier, which provides high computing power and supports eight different power modes. We measure the response times of all three applications with and without the scheduler on the NVIDIA AGX Xavier platform on different power modes, to evaluate the effectiveness of the scheduler. / Master of Science / Autonomous mobile robots for general human services have increased significantly due to ever-growing technology. The common applications of these robots include delivery services, search and rescue, hotel services, and so on. This thesis focuses on implementing the computational tasks performed by these robots as well as designing the task scheduler, to improve the overall performance of these tasks. The embedded hardware is resource-constrained with limited memory, power, and operating frequency. The use of a graphical processing unit (GPU) for executing the tasks to speed up the operation has increased with the development of the GPU programming framework. We propose a software-based GPU scheduler to execute the functions on GPU and get the best possible performance from the embedded hardware.

Two-dimensional (2D) nanoscale confinement effects on poly(ε-caprolactone) (PCL) crystallization were probed through crystallization studies of PCL-b-poly(tert-butyl acrylate) (PCL-b-PtBA) copolymers, PCL with bulky tri-tert-butyl ester endgroups (PCL triesters), PCL with triacid end groups (PCL triacids), and magnetic nanoparticles stabilized by PCL triacid (PCL MNPs) at the air/water (A/W) interface. Thermodynamic analyses of surface pressure-area per monomer (Π−A)) isotherms for the Langmuir films at the A/W interface showed that PCL-b-PtBA copolymers, PCL triheads and PCL MNPs all formed homogenous monolayers below the dynamic collapse pressure of PCL, Π_C ~11 mN•m⁻¹. For compression past the collapse point, the PCL monolayers underwent a phase transition to three-dimensional (3D) crystals and the nanoscale confinements impacted the PCL crystalline morphologies. Studies of PCL-b-PtBA copolymers revealed that the morphologies of the LB-films became smaller and transitioned to dendrites with defects, stripes and finally nano-scale cylindrical features as the block length of PtBA increased. For the case of PCL triester, irregularly shaped crystals formed at the A/W interface and this was attributed to the accumulation of bulky tert-butyl ester groups around the crystal growth fronts. In contrast, regular, nearly round-shaped lamellar crystals were obtained for PCL triacids. These morphological differences between PCL triacids and PCL triesters were molar mass dependent and attributed to differences in dipole density and the submersion of carboxylic acid groups in the subphase. Nonetheless, enhanced uniformity for PCL triacid crystals was not retained once the polymers were tethered to the spherical surface of a PCL MNP. Instead, the PCL MNPs exhibited small irregularly shaped crystals. This nano-scale confinement effect on the surface morphology at the A/W interface was also molar mass dependent. For the small molar mass PCL MNPs, two layers of collapsed nanoparticles were observed. In a later chapter, studies of polyethylene glycol (PEG) surfactant adsorption onto phospholipid bilayers through quartz crystal microbalance with dissipation monitoring (QCM-D) measurements revealed a strong dependence of the adsorption and desorption kinetics on hydrophobic tail group structure. PEG surfactants with a single linear alkyl tail inserted and saturated the bilayer surface quickly and the surfactants had relatively fast desorption rates. In contrast, PEG lipids, including dioleoyl PEG lipids and cholesterol PEGs, demonstrated slower adsorption and desorption kinetics. The interactions of Pluronics and Nonoxynol surfactants with phospholipid bilayers were also studied. Pluronics showed no apparent affinity for the phospholipid bilayer, while the Nonoxynol surfactants damaged the lipid bilayers as PEG chain length decreased. / Ph. D.

<p dir="ltr">Many phenomena in physics, engineering, and biology depend strongly on geometry; however, deriving analytic (and sometimes numerical or simulation) solutions to describe these phenomena for realistic geometries may be challenging or impossible. This thesis applies coordinate invariant mathematics to describe several key multidisciplinary problems.</p><p dir="ltr">The first phenomenon that we explore is space-charge-limited current (SCLC), which corresponds to the maximum steady-state current that can be injected into a diode. First derived by Child and Langmuir and described by the eponymous Child-Langmuir law for a one-dimensional, planar diode, SCLC is critical for numerous applications, including electric thrusters, Hall thrusters, directed energy, high-power microwaves, vacuum nanotransistors, and satellites. The SCLC is a critical limit to operation and many studies have sought ways to exceed it; however, this requires better understanding of the SCLC in more realistic geometries, motivating extensions to nonplanar and multidimensional geometries. However, many devices employ a crossed-field geometry in which a magnetic field is applied orthogonal to the electric field to enhance power output. This thesis applies variational calculus and capacitance to derive two sets of solutions for the SCLC in nonplanar crossed-field diodes.</p><p dir="ltr">The first set of solutions is found using scale factors and variational calculus. Variational calculus minimizes the gap energy to solve for the path of least resistance. The scale factors, which are the lengths of the local basis vectors, generalize the process. Models can be produced in variational calculus using the spatial domain alone, eliminating the need for the time domain transformation required by all other crossed-field approaches. This approach creates a powerful, numerically solvable solution for the SCLC in any orthogonal geometry, although it may be computationally expensive.</p><p dir="ltr">The second set of solutions is created by treating the diode as a capacitor and using the capacitance equations to find the SCLC. After finding a planar solution, the solution was generalized by combining conformal mapping and magnetic field mapping by leveraging the innately geometric definition of the Hull cutoff. The Hull cutoff, the magnetic field required to insulate the electron flow, is calculated across geometries to find a mapping factor for the magnetic field allowing the application of conformal mapping, a method of geometric translation that is normally unusable in crossed-field systems. This approach greatly reduces the computational expense and complexity present in other crossed-field approaches.</p><p dir="ltr">In Chapter 4, we apply Lie point symmetries to extend theories for spherical avascular tumor growth to spheroidal tumor growth. Lie point symmetries reduce the complexity of ordinary differential equations, providing a simpler, and sometimes the only, path to a solution. In this chapter, we apply Lie point symmetries to four types of tumors: prolate and oblate spheroids without a necrotic core, an area of dead cells often found at the center of larger tumors, and prolate and oblate spheroids with a necrotic core. Lie point symmetries simplify the differential equations in all four cases and make it possible to solve the prolate spheroid without a necrotic core.</p><p dir="ltr">The results from this thesis provide valuable insight to computational physicists benchmarking particle-in-cell simulations for determining SCLC for crossed-field diodes. Additionally, elucidating the physical phenomena in more realistic diodes can facilitate further optimization for many applications of crossed fields, such as magnetrons. The tumor growth models demonstrate the applicability of this approach to a dramatically different problem and could provide value to characterizing more realistic shapes.</p>

Interpreter services play an integral role in ensuring equity in healthcare for patients with limited English proficiency (LEP), whose language barrier places them at increased risk for healthcare disparities. Even with the growing number of non-English-speaking patients, a sizeable number being Spanish-speaking, and although such training leads to more culturally competent care with better patient outcomes, there is little curricular time during medical school devoted to effectively using interpreters. This study aimed to understand better how medical education prepares future physicians for their encounters with LEP patients and what experiences they would appreciate in their medical training. Temple LKSOM student from the class of 2024-2027 (M1-M4s), were recruited through flyers and educator announcements to participate in three virtual focus groups with a total of 26 participants. Qualitative data analysis resulted in five themes which were: students felt that interpreters were integral to culturally competent care, students who speak another language have the undue burden of interpreting even when not comfortable doing so, students felt that there was not enough training in medical school regarding various types of interpreters, how to reach them or how to use them properly, students are open to doctoring sessions or simulations with non-English speaking standardized patients and interpreters, and the final theme was that there mixed feelings amongst students regarding the desire to have OSCEs with non-English speaking standardized patients and interpreters. / Urban Bioethics

Limited literacy remains a prevailing issue among older adult populations. This qualitative study sought to answer the following research questions: How do older adults with limited literacy skills navigate and learn to navigate their daily lives in an advanced literate community such as the United States? What types of informal learning strategies and coping mechanisms have been used by these adults, and what perceived barriers and hindrances have participants faced and are facing in their lives? The study included the interviews, data collection and analysis of five women and two men, ages 67-87, two of whose activities also were observed by the researcher. The objective was to investigate their informal learning strategies and coping mechanisms within their current living environment. A thematic analysis of the seven narrative 'life stories' resulted in the emergence of four themes, which represented how these adults with limited literacy skills learned to navigate their daily lives and use informal learning strategies and coping mechanisms to survive in a changing environment: (a) Family support (or lack thereof), (b) social networks, (c) desired GED Program engagement, (d) self-directed gained knowledge. The study concluded that although none of the participants received a high school diploma, all successfully obtained employment and navigated their daily lives by incorporating various strategies. Likewise, given their implementation of self-directed learning strategies (Ausubel, 2000; Knowles, 1990; McClusky, 1974; Tough, 1982), participants viewed some of the dispositional, institutional, and situational obstacles (Cross, 1982), not as barriers, but as navigable and surmountable challenges. Implications of the study suggested limited literacy adults relied upon family support, social networks and self-direction to pursue knowledge and conceal limited literacy. They gained confidence and developed coping mechanisms to navigate daily activities, circumvent barriers and function in an advanced literate society. Future professional practice recommendations included incorporating ABE/GED programs at adult living facilities/community centers; invalidating false assumptions regarding limited literacy older adults; volunteering time and building trust with these adults; and validating their current and desired needs. Research recommendations included investigating limited literacy adult capabilities; shadowing their navigation; conducting similar studies in other U.S. regions; and investigating comparative life-span research. / Ph.D.

We introduce a framework that would enable using autonomous aerial vehicles in search and rescue scenarios associated with missing person incidents to assist human searchers. We formulate a lost person behavior model and a human searcher model informed by data collected from past search missions. These models are used to generate a probabilistic heatmap of the lost person's position and anticipated searcher trajectories. We use Gaussian processes with a Gibbs' kernel for data fusion to accurately model a limited field-of-view sensor. Our algorithm thereby computes a set of trajectories for a team of aerial vehicles to autonomously navigate, so as to assist and complement human searchers' efforts. / Master of Science / Our goal is to assist human searchers using autonomous aerial vehicles in search and rescue scenarios associated with missing person incidents. We formulate a lost person behavior model and a human searcher model informed by data collected from past search missions. These models are used to generate a probabilistic heatmap of the lost person’s position and anticipated searcher trajectories. We use Gaussian processes for data fusion with Gibbs’ kernel to accurately model a limited field-of-view sensor. Our algorithm thereby computes a set of trajectories for a team of aerial vehicles to autonomously navigate, so as to assist and complement human searchers’ efforts.

Firms seek independent assurance from accountants on their Corporate Social Responsibility (CSR) disclosures for various reasons, including to enhance the credibility of such disclosures or to enhance the reliability of management's CSR report. However, there are multiple levels of assurance available for CSR disclosures. The forthcoming clarified U.S. attestation standards re-frame the two levels of assurance on non-financial information as reasonable (higher) and limited (lower). While not currently addressed by U.S. standards, accountants also issue hybrid reports with both reasonable and limited assurance on CSR disclosures. I conduct an experiment to identify differences in nonprofessional investors' perceptions of CSR disclosures when reasonable, limited, or hybrid assurances are provided and manipulate firm CSR performance as a possible moderator for the influence of assurance. Findings indicate that nonprofessional investors find CSR disclosures on greenhouse gas emissions to be credible, and the degree of credibility does not vary significantly based on the firm's performance in controlling emissions or on the level of assurance provided by an accountant. However, nonprofessional investors do differ in their perceptions of the overall reliability of representations made in management's CSR report. While management's CSR report supported by hybrid assurance is generally perceived to be as reliable as when only limited or only reasonable assurance is provided, the perceived reliability differs between limited and reasonable assurance. Supplemental analyses reveal an interaction such that management's CSR report is perceived as more reliable with limited assurance rather than with reasonable or no assurance for firms with better performance at controlling greenhouse gas emissions; this association reverses for firms with worse performance. This interaction may be due, in part, to language in limited assurance reports that makes it clear higher assurance was available but not pursued by management. Results address a gap in the literature for hybrid assurance and show that nonprofessional investors find management's CSR report with hybrid assurance to generally be as credible and reliable as when either limited or reasonable assurance is provided. Further, results offer insight into the interactive effects of firm performance and level of assurance on nonprofessional investors' perceptions of the reliability of management's CSR report. / Ph. D.

The Range Limited Antenna (RLA) is a device, which accurately estimates the range of incoming signals and rejects those that arrive from outside a certain, pre-determined range. This task is accomplished by using two multi-element arrays and applying direction finding (DF) algorithms on each of them. Rectangular, single-layer, coax-fed patch antennas are used as array elements for the specific purpose of tracking cell phones operating in the PCS band inside a given building. It is vital to ensure that the patch antenna is designed in such a manner that it resonates at the desired frequency. This thesis introduces the Agilent High Frequency Structure Simulator (HFSS) as an effective tool for modeling electromagnetic structures. It presents a comprehensive and meticulous description of the process of modeling a rectangular coax-fed patch antenna in HFSS. Plots of S-parameter values are calculated and are compared with WIPL-D, which is another simulation software program, and with measurements performed at the George Washington University. Various important parameters of the HFSS simulation are varied and their effects are investigated to provide a deeper understanding of the program. / Master of Science

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