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Recent Submissions

  • An Africological Re-Imagination of Notions of Freedom and Unfreedom in a Colonial Context: Deconstructing the Cayman Islands as Paradise

    Johnson, Amari; Nehusi, Kimani S. K.; Neptune, Harvey R., 1970-; Henry, Paget (Temple University. Libraries, 2022)
    In the Cayman Islands, one is raised to be the managers of someone else’s financial empire; the empire of the United Kingdom to be precise. Historically, whenever there are whispers about political independence among the population, they are abruptly quieted by a chorus of familiar rhetoric that attributes the success of business and tourism industries on island to its administrative financial connection to the United Kingdom. In a colony where most people rarely think of themselves as colonized, to the majority of Caymanians there is nothing improper about this relationship, it is simply the way things have been. On the few occasions where there is sustained conversation on the topic of political independence, like clockwork, the dialogue often takes a decidedly anti-Jamaican and anti-black tone that positions the so-called socioeconomic “struggles” of Jamaica as a cautionary tale on the perils of political independence. Perils that are then juxtaposed with the so-called socioeconomic success of Cayman which are framed as the prosperity of political dependency. It is this enduring conversation that warrants further interrogation; how and why African descended persons are actively choosing to not be self-determining. Much of the current literature interrogates the colonial presence in the Caribbean in a historical context. However, my interest is in how modern-day manifestations of colonialism (economic, cultural) impacted understandings of agency and freedom? Moreover, Caribbean scholarly discourses on colonialism tend to situate it in the past, instead a present, ongoing reality in the region today. This project centers Caymanians and their understanding of their own humanity outside of what they provide to others. My work seeks to disrupt the concept of ‘Paradise’ in the Caribbean; a concept evoked in order to provide leisure for tourists (mostly originating from North America and Western Europe) and make the financial management of the wealth of the ruling elite from the same places as those tourists desirable. This research interrogates a humanity that is agentic, self-conscious, and decolonial.

    Balsam, Steven; Brown, Lawrence D. (Lawrence David), 1946-; Mao, Connie X.; Rytchkov, Oleg (Temple University. Libraries, 2022)
    Using state charitable tax subsidy rates to proxy for tax incentives, I examine the effect of donors’ charitable tax incentives on the relation between donor contributions and nonprofit organizations’ (NPOs) program efficiency, following Weisbrod and Dominguez (1986) who model a negative relation between charitable tax incentives and NPO program efficiency. I focus my study on NPOs with large donors (i.e., donors that make a single contribution of $5,000 or more) because large donors are more likely to be the beneficiaries of these tax incentives given that the incentives lower their after-tax cost of giving. In addition, NPOs typically appoint large donors to the board, which places these donors in a position to influence NPO efficiency. I use Form 990 Schedule B data to identify NPOs that have one or more large donors, and I find that as state tax rates increase, an increase in donor contributions is associated with higher NPO program efficiency. The results suggest that contrary to the expectations of Weisbrod and Dominguez (1986), tax incentives do not have a negative effect on NPO program efficiency in NPOs with large donors. Rather, my results are consistent with large donors having higher efficiency expectations and being more likely to ensure that the NPO operates efficiently. Given that large donors on the NPO’s board can influence NPO program efficiency and based on the expected negative effect of taxes on the relation between donor contributions and NPO program efficiency predicted by Weisbrod and Dominguez (1986), I further examine whether the effect of donor tax incentives on the relation between donor contributions and NPO program efficiency in NPOs with large donors differ by board size, board independence, and state regulations. While the coefficients indicate that tax incentives have a more positive effect on the relation between donor contributions and NPO program efficiency for NPOs with large board sizes compared to NPOs with small board sizes, Wald statistics indicate that the results do not differ statistically between NPOs split by board sizes. However, the results examining the effect of board independence indicate that NPO program efficiency is higher in NPOs with independent boards compared to those with non-independent boards, suggesting that an independent board has a positive differential impact on how tax incentives affect the relation between donor contributions and NPO program efficiency. Conversely, the results indicate that there is no statistical difference in the effect of tax incentives on the relation between donor contributions and NPO program efficiency between samples split by state regulations. Taken together, the results suggest that while NPO board size and state governance do not impact how tax incentives affect the relation between donor contributions and NPO program efficiency, an independent board has a positive impact on how tax incentives affect the relation between donor contributions and NPO program efficiency. In additional tests, I use changes in state tax rates to examine the effect of tax incentives on the relation between donor contributions and NPO program efficiency. The results show that state tax rate changes (decreases and increases) do not affect the relation between donor contributions and NPO program efficiency. I also conduct tests using federal tax changes to proxy for tax incentives. I first exploit the exogenous shock from the 2017 Tax Cuts and Jobs Act (TCJA) to examine changes in program efficiency, and the results are statistically insignificant, indicating that the TCJA had no effect on the relation between donor contributions and NPO program efficiency. Thereafter, I use the percentage of itemizers in each state as a proxy for tax incentives, and the results also suggest that the percentage of itemizers does not affect the relation between donor contributions and NPO program efficiency.
  • Application of Hidden Markov Model to Auto Telematics Data and the Effect of Universal Demand Law Change on Corporate Risk Taking in the U.S. Property & Casualty Insurance Industry

    Shi, Tianxiang; Grace, Martin Francis, 1958-; Viswanathan, Krupa S.; Basu, Sudipta, 1965- (Temple University. Libraries, 2022)
    There are two themes in this dissertation, that is, the effect of universal demand law change on corporate risk-taking in the U.S. property & casualty insurance industry, and the application of hidden Markov model to auto telematics data. The first chapter presents my study in the first theme and the rest two chapters present the other theme. In Chapter 1, "Does Shareholder Litigation Affect Corporate Risk-Taking? Evidence from the Property-Casualty Insurance Industry", I explore whether shareholder litigation affects corporate risk-taking differently depending on distinct organizational structures. I use a law change, called Universal Demand (UD) Law, as an exogenous shock and develop three risk-taking measures that are unique in the U.S. property-casualty insurance industry: leverage risk, asset risk, and underwriting risk. The insurance industry provides an interesting opportunity for the study as shareholders in mutual insurers are an ambiguous concept in the legal world, as opposed to the common argument in the insurance literature. The results show that along with UD law adoption, insurers increase their risk-taking. After taking organizational structures into account, the impact of the law change differentiates. Stock insurers increase all three risk-taking measures while mutual insurers decrease their Leverage Risk and increase Asset Risk measures. For different time windows, stock insurers respond faster with respect to their Asset Risk compared to mutual insurers. In addition, I proceed to examine the main economic channel for the impact and find that the free cash flow argument is not the main channel. Chapters 2 and 3 present the study in auto telematics data using a proprietary data source. Both studies are based on the application of hidden Markov model (HMM). Specifically, Chapter 2, "Auto Insurance Pricing Using Telematics Data: Application of a Hidden Markov Model", develops an HMM-based clustering framework to predict auto insurance losses using driving characteristics extracted from telematics data. Through a simulation experiment based on a proprietary telematics data set, I show that HMM can effectively classify driving trips using model-implied hidden states, and HMM-based pricing methods provide better predictive power measured by both deviance statistics and mean squared error. Importantly, the proposed framework not only enables us to price usage-based insurances at a granular level, but it is also viable for estimating long-term insurance losses utilizing the limiting properties of HMM. Chapter 3, "Theoretical Framework of a 3-Layer Hidden Markov Model for Auto Insurance Pricing", is a theoretical extension of the second chapter to improve the framework at a more granular level. I develop a 3-layer HMM for risk classification, which links driving behavior characteristics with risk classes and loss estimation. The proposed model presents a direct structure among all variables and utilizes time series data without aggregation. Furthermore, this study provides a theoretical framework to estimate the 3-layer HMM using the Expectation-Maximization (EM) algorithm. The parameters of Bernoulli distributed loss count (per unit of time) and Gamma distributed loss severity can be solved at least numerically, and the negative definite Hessian matrix indicates that the solution of the first-order condition of the log-likelihood function achieves its local maximum.

    Houser, Steven R.; Tian, Ying; Litvin, Judith; Sabri, Abdelkarim; Kiani, Mohammad F. (Temple University. Libraries, 2022)
    Cardiac diseases such as myocardial infarction (MI) can lead to adverse remodeling and impaired contractility of the heart due to widespread cardiomyocyte death in the damaged area. Current therapies focus on improving heart contractility and minimizing fibrosis with modest cardiac regeneration, but MI patients can still progress to heart failure (HF). There is a dire need for clinical therapies that can replace the lost myocardium, specifically by the induction of new myocyte formation from pre-existing cardiomyocytes. Many studies have shown terminally differentiated myocytes can re-enter the cell cycle and divide through manipulations of the cardiomyocyte cell cycle, signaling pathways, endogenous genes, and environmental factors. However, these approaches result in minimal myocyte renewal or cardiomegaly due to hyperactivation of cardiomyocyte proliferation. Finding the optimal treatment that will replenish cardiomyocyte numbers without causing tumorigenesis is a major challenge in the field. Another controversy is the inability to clearly define cardiomyocyte division versus myocyte DNA synthesis due to limited methods. A recent study suggests that systemic hypoxemia in adult male mice can induce cardiac myocytes to proliferate. The goal of the present experiments was to confirm these results, provide new insights on the mechanisms that induce cardiomyocyte cell cycle re-entry, and to determine if hypoxemia also induces cardiomyocyte proliferation and division in female mice. EdU mini pumps were implanted in 3-month-old, male and female C57BL/6 mice. Mice were then placed in a hypoxia chamber and the oxygen was lowered by 1% every day for 14 days to reach 7% oxygen. The animals remained in 7% inspired oxygen for 2 weeks before terminal studies. Myocyte cell cycle re-entry and division was also studied with a mosaic analysis with double markers (MADM) mouse model. MADM mice were exposed to hypoxia at 7% Oxygen as described above. Hypoxia induced cardiac hypertrophy in both left ventricular (LV) and right ventricular (RV) myocytes, with LV myocytes lengthening and RV myocytes widening and lengthening. Hypoxia induced a small increase in cardiomyocytes undergoing DNA synthesis (EdU+) in male and female C57BL/6 mice. Hypoxia induced a significant increase in myocyte cell cycle re-entry in MADM mice, but few myocytes synthesized new DNA (EdU+) and completed cytokinesis. RNA-sequencing showed upregulation in mitotic cell cycle processes but a downregulation of promoter genes for G1 to S phase transition in hypoxic mice when compared to control mice. There was also proliferation of non-myocyte cells and mild cardiac remodeling in hypoxic mice that did not disrupt cardiac function. Male and female mice exhibited similar gene expression profiles following hypoxia. Thus, systemic hypoxia induces adult cardiac myocyte cell cycle re-entry, but very few adult myocytes progress through the cell cycle to synthesize new DNA and divide into two daughter cells.

    Stull, Judith C., 1944-; McGinley, Christopher W.; Burke, Katey; Boyer, Jean A. (Temple University. Libraries, 2022)
    This study attempted to address gaps in how the perceptions of special education teachers had an effect on how they taught, and the support they receive from their leadership. The purpose of the study was to examine how the perception of special education teachers affects how they approach teaching career readiness attitudes and skills that are embedded in the hidden curriculum, and their perception of the support from leadership that they receive. This is an important issue because as students navigate through school and look toward post-secondary opportunities, having been exposed to the “soft skills” they will need to be successful in a vocational setting is essential. Also, the perspective of the special education teacher is important because they can provide insight and work in collaborative manners with both other teachers and leaders.Data were collected through surveys and interviews from current special education teachers or from those who previously were special education teachers. This latter category does include respondents who transitioned from teaching to administrative positions. There was a total of 11 survey participants and 20 interviews were conducted. The survey was based on the National Teacher and Principal Survey (NTPS) and the ECLS program (2020). These two surveys have been used by researchers to capture teacher attitudes and behaviors related to the topic at hand. For example, Merlin (2021) used the NTPS data to capture the pre-service experiences of a nationally represented sample. Jennings and DiPrete (2010), analyzed ECLS data and found that some aspects of academic achievement are a function of teacher effects on social and behavioral skills. Breinholt and Jaeger (2020) found a positive relationship between teachers focusing on developing students’ cultural capital and their educational performance. Other researchers used these data to understand better classroom experiences for students with disabilities (Bowling et al, 2017; Jung & Bradley, 2006; Rhinehart, et al., 2022). The majority of the survey respondents felt that it was important to cover class content, and fewer thought that helping students work with others or including work readiness skills were important. The survey provided the foundation to dig deeper into the experiences of special education teachers. The interviews provided an elaborate account of the experiences and perceptions of special education teachers. The results provided themes that could answer the research questions. The findings provide insight into how special education teachers and other educators teach and work with students with disabilities. The implications of this study can inform policy and practice for special education teachers and school leadership. It can also help build collaborative efforts between leadership, special education teachers, and general education teachers. Additional research is needed to further examine how the perceptions of other educators, and school leadership affects the teaching of students with disabilities.
  • Improving the Accuracy of Density Functional Approximations: Self-Interaction Correction and Random Phase Approximation

    Ruzsinszky, Adrienn; Ruzsinszky, Adrienn; Perdew, John P.; Wu, Xifan; Carnevale, Vincenzo (Temple University. Libraries, 2022)
    Complexes containing a transition metal atom with a 3d^4 - 3d^7 electron configuration typically have two low-lying, high spin (HS) and low spin (LS) states. The adiabatic energy difference between these states, known as the spin-crossover energy, is small enough to pose a challenge even for electronic structure methods that are well known for their accuracy and reliability. In this work we analyze the quality of electronic structure approximations for spin-crossover energies of iron complexes with four different ligands by comparing energies from self-consistent and post-self-consistent calculations for methods based on the random phase approximation and the Fermi-L\"{o}wdin self-interaction correction. Considering that Hartree-Fock densities were found by Song et al. J. Chem. Theory Comput. 14,2304 (2018) to eliminate the density error to a large extent, and that the Hartree-Fock method and the Perdew-Zunger-type self-interaction correction share some physics, we compare the densities obtained with these methods to learn about their resemblance. We find that evaluating non-empirical exchange-correlation energy functionals on the corresponding self-interaction-corrected densities can mitigate the strong density errors and improves the accuracy of the adiabatic energy differences between HS and LS states.

    Vucetic, Slobodan; Obradovic, Zoran; Dragut, Eduard Constantin (Temple University. Libraries, 2022)
    Medical health providers use electronic health records (EHRs) to store information about patient treatment to support patient care management and securely share health information among healthcare organizations. EHRs have also been used in healthcare research in problems such as patient phenotyping, health risk prediction, and medical entity extraction. In this thesis, we focus on several important issues: (1) how to convert natural text from medical notes to vector representations suitable for deep learning algorithms, (2) how to help healthcare researchers select a patient cohort from EHRs, and (3) how to use EHRs to identify patient diagnoses and treatments. In the first part of the thesis, we present a new method for learning vector representations of medical terms. Learning vector representations of words is an important pre-processing step in many natural language processing applications. For example, EHRs contain clinical notes that describe patient health conditions and course of treatment in a narrative style. The notes contain specialized medical terminology and many abbreviations. Learning good vector representations of specialized medical terms can improve the quality of downstream data analysis tasks on EHR data. However, the traditional approaches struggle to learn vector representations of rarely used medical terms. To overcome this problem, we developed a neural network-based approach, called definition2vec, that uses external knowledge contained in medical vocabularies. We performed quantitative and qualitative analysis to measure the usefulness of the learned representations. The results demonstrate that definition2vec is superior to the state-of-the-art algorithms. In the second part of the thesis, we describe a new visual interface that helps healthcare researchers select patient cohorts from EHR data. Process of identifying patients of interest for observational studies from EHR data is known as cohort selection, a challenging research problem. We considered a problem of cohort selection from medical claim data, which requires identifying a set of medical codes for selection. However, there are tens of thousands of unique medical codes, and it becomes very difficult for any human to decide which codes identify patients of interest. To help users in defining a set of codes for cohort identification, we developed an interactive system, called Medical Claim Visualization system (MedCV), which visualizes medical code representations. MedCV analyzes a medical claim database and allows users to reason about medical code relationships and define inclusion rules for the selection by visualizing medical codes, claims, and patient timelines. Evaluation of our system through a user study indicates that MedCV enables domain experts to define inclusion rules efficiently and with high quality. The third part of the thesis is a study of the definition of acute kidney injury (AKI), which is a condition where kidneys suddenly cannot filter waste from the blood. AKI is a major cause of patient death in intensive care units (ICU) and it is critical to detect it early. Recently published KDIGO medical guideline proposed a clinical definition of AKI using blood serum creatinine and urine output. The KDIGO definition was developed based on the expert knowledge, but very little is known about how well it matches the medical practice. In this study, we investigated publicly available EHR data from 47,499 ICU admissions to determine the concordance between the KDIGO definition and AKI determination by the medical provider. We show that it is possible to find a formula using machine learning with much higher concordance with the medical provider AKI coding than KDIGO and discuss the medical relevance of this finding.

    Stover, Matthew; Futer, David; Taylor, Samuel J.; Meyer, Jeffrey (Temple University. Libraries, 2022)
    The classical spherical and Euclidean geometries are easy to visualize and correspond to spaces with constant curvature 0 and +1 respectively. The geometry with constant curvature −1, hyperbolic geometry, is much more complex. A powerful theorem of Mostow and Prasad states that in all dimensions at least 3, the geometry of a finite-volume hyperbolic manifold (a space with local d-dimensional hyperbolic geometry) is determined by the manifold's fundamental group (a topological invariant of the manifold). A cusp is a part of a finite-volume hyperbolic manifold that is infinite but has finite volume (cf. the surface of revolution of a tractrix has finite area but is infinite). All non-compact hyperbolic manifolds have cusps, but only finitely many of them. In the fundamental group of such a manifold, each cusp corresponds to a cusp subgroup, and each cusp subgroup is associated to a point on the boundary of H^d, which can be identified with the (d − 1)-sphere. It is known that there are many one-cusped two- and three-dimensional hyperbolic manifolds. This thesis studies restrictions on the existence of 1-cusped hyperbolic d-dimensional manifolds for d ≥ 3. Congruence subgroups belong to a special class of hyperbolic manifolds called arithmetic manifolds. Much is known about arithmetic hyperbolic 3- manifolds, but less is known about arithmetic hyperbolic manifolds of higher dimensions. An important infinite class of arithmetic d-manifolds is obtained using SO(n, 1; Z), a subset of the integer matrices with determinant 1. This is known to produce 1-cusped examples for small d. Taking special congruence conditions modulo a fixed number, we obtain congruence subgroups of SO(n, 1; Z) which also have cusps but possibly more than one. We ask what congruence subgroups with one cusp exist in SO(n, 1; Z). We consider the prime congruence level case, then generalize to arbitrary levels. Covering space theory implies a relation between the number of cusps and the image of a cusp in the mod p reduced group SO(d+ 1, p), an analogue of the classical rotation Lie group. We use the sizes of maximal subgroups of groups SO(d + 1, p), and the maximal subgroups' geometric actions on finite vector spaces, to bound the number of cusps from below. Let Ω(d, 1; Z) be the index 2 subgroup in SO(d, 1; Z) that consists of all elements of SO(d, 1; Z) with spinor norm +1. We show that for d = 5 and d ≥ 7 and all q not a power of 2, there is no 1-cusped level-q congruence subgroup of Ω(d, 1; Z). For d = 4, 6 and all q not of the form 2^a3^b, there is no 1-cusped level-q congruence subgroup of Ω(d, 1; Z).
  • Construction of first-principles density functional approximations and their applications to materials

    Perdew, John P.; Ruzsinszky, Adrienn; Napolitano, Jim; Matsika, Spiridoula (Temple University. Libraries, 2022)
    Kohn-Sham density functional theory is a rigorous formulation of many-electron quantum mechanics which, for practical purposes, requires approximation of one term in its total energy expression: the exchange-correlation energy. This work elucidates systematic methods for constructing approximations to the exchange-correlation energy solely from first-principles physics. We review the constraints that can be built into approximate density functionals, and use thermochemical data to argue that satisfaction of these constraints permits a more general description of electronic matter. Contact with semiclassical physics is made by studying the turning surfaces of Kohn-Sham potentials in solids. Perfect metals and covalently-bound, narrow-gap insulators do not have turning surfaces at equilibrium, but do under expansive strain. Wide-gap insulators, ionic crystals, and layered solids tend to have turning surfaces at equilibrium. Chemical bonds in solids are classified using the turning surface radii of its constituent atoms. Depletion of the charge density, such as near a monovacancy in platinum, is shown to produce a turning surface. Further, this work demonstrates why generalized gradient approximations (GGAs) are often able to describe some properties of sp-bonded narrow-gap insulators well. A Laplacian-level pure-density functional is developed with the goal of describing metallic condensed matter. This functional is derived from the r2SCAN orbital-dependent meta-GGA, and reduces its tendency to over-magnetize ferromagnets; improves its description of the equation of state properties of alkali metals; and improves its description of intermetallic thermodynamics. It is constructed to enforce the fourth-order exchange gradient expansion constraint (not satisfied by r2SCAN), and a few free parameters are fitted to paradigmatic metallic systems: jellium surfaces and closed-shell jellium clusters. Last, we modify an exchange-correlation kernel that describes the density-density response of jellium to better satisfy known frequency sum rules. We also constrain the kernel to reproduce the correlation energies of jellium, and compare it to a wide variety of common kernels in use for linear response, time-dependent density functional theory calculations.

    Matsika, Spiridoula; Carnevale, Vincenzo; Borguet, Eric; Remsing, Rick (Temple University. Libraries, 2022)
    n-Cyanoindole (n=2-7) fluorescent probes were developed for studying the structure and dynamics of proteins. It has been observed that cyano substitution at the 4-position of the bicyclic ring of indole dramatically increases the relative fluorescence intensity, lifetime, and quantum yield, while functionalizing other positions quenches the fluorescence in aqueous solution. We studied the positional substituent effect on the absorption and fluorescence properties using high-level quantum mechanical methods. In addition, we modeled the important solvation effects found in the interaction between the parent probe, indole, and water solvents using explicit solvation models and molecular dynamics simulations. We have unraveled the important non-radiative decay pathways that govern the fluorescence quenching of the probes in aqueous solution using water cluster models. It was found that upon excited state relaxation, water solvent stabilizes the La(ππ∗) excited state below the Lb(ππ∗) state when substitution takes place on the 6 membered ring causing (4-7)-cyanoindole to fluoresce from the bright La state and 2- and 3-cyanoindole to fluoresce from the dim Lb state. 4-cyanoindole was found to exhibit optimal fluorescence properties because it absorbs to and emits from the S1 excited state and has a high energy barrier in the S1 state potential energy surface along the N-H bond stretch which minimizes access to all non-radiative decay pathways. We also found that explicitly modeling the mutual polarization effects is essential to reproducing the features of the absorption spectrum of indole and the state inversion during fluorescence in aqueous solution. Furthermore, we found that the formation of a cyclic excimer structure results in different photochemical reaction paths such as excited state hydrogen transfer, excited state proton transfer, and excited state proton-coupled electron transfer processes, which if accessed, have the potential to rapidly quench the fluorescence intensity. However, the presence of a high energy barrier traps the 2-, 6-, and 7-cyanoindole-(H2O)1−2 clusters at the S1 state minimum, and thus the fluorescence is quenched due to vibrational relaxation and internal conversion from the S2 state at absorption to the S1 equilibrium geometry at emission.
  • Proctored versus Unproctored Math Placement Tests: Does It Matter?

    DuCette, Joseph P.; Fukawa-Connelly, Timothy; Paris, Joseph H.; Torsney, Benjamin (Temple University. Libraries, 2022)
    Many institutions use placement tests as a method to assess students’ readiness for college-level coursework. With the increased use of technology in testing, many institutions have transitioned placement test administration to an online format in an unproctored setting. While unproctored placement tests may provide financial and logistical benefits for institutions and students, it is important to examine if there are differences in academic outcomes when tests are administered in this format. Guided by the literature on test administration modality (i.e., proctored versus unproctored examinations), I examined if there are differences in math course performance and college student enrollment persistence between students who completed a proctored or unproctored math placement test. To investigate these important educational outcomes, I analyzed data collected as part of a 2018 randomized control trial conducted at a large, urban public institution in the Mid-Atlantic region of the United States in which incoming, first-year students were randomly assigned to a proctored or unproctored group to complete a math placement assessment. The current study affirmed findings from a pilot study, which suggests that students tend to place approximately one course level lower when placed using a proctored math placement test compared to an unproctored placement test and that students tend to have higher final grades in their initial math course when placed by a proctored math placement test.The current study analyzed final grades in the second math course taken between proctored and unproctored groups as well as student persistence. Analyzing mean course grades, I found that differences in grades between students who take a proctored and unproctored math placement test continue in some cases into the second math course. The percentage of F’s and withdrawals for initial and second math course final grades between students who take a proctored and unproctored math placement assessment also show differences between groups. Applying hierarchical linear regression, suggests that test administration modality does not account for a significant amount of variance in course grades. When controlling for demographic characteristics and academic factors, performance from the initial course taken, was found to be the most significant factor of grades in second math course taken. Results from the current study suggests that test administration modality during math placement tests while not a statistically significant variable in academic performance in second math course taken, may still be helpful as it is a statistically significant variable in academic performance in the first math course taken. Since initial math course grades were statistically significant in explaining the difference in grades between groups, institutions should consider using proctoring during math placement tests as a practice. Further research should be conducted, however, to understand how test administration modality during placement tests affects students in different programs, including programs that do not require courses along the institution’s math course sequence. Additionally, further research on types of proctoring would provide a more comprehensive understanding of the proctoring options available to institutions and whether they result in the same outcomes for students.
  • Optimizing Memory Systems for High Efficiency in Computing Clusters

    He, Xubin; Kant, Krishna; Ji, Bo, 1982-; Liu, Qing, 1979-; Zhao, Zhigen (Temple University. Libraries, 2022)
    DRAM-based memory system suffers from increasing aggravating row buffer interference, which causes significant performance degradation and power consumption. With DRAM scaling, the overheads of row buffer interference become even worse due to higher row activation and precharge latency. Clusters have been a prevalent and successful computing framework for processing large amount of data due to their distributed and parallelized working paradigm. A task submitted to a cluster is typically divided into a number of subtasks which are designated to different work nodes running the same code but dealing with different equal portion of the dataset to be processed. Due to the existence of heterogeneity, it could easily result in stragglers unfairly slowing down the entire processing, because work nodes finish their subtasks at different rates. With the increasing problem complexity, more irregular applications are deployed on high-performance clusters due to the parallel working paradigm, and yield irregular memory access behaviors across nodes. However, the irregularity of memory access behaviors is not comprehensively studied, which results in low utilization of the integrated hybrid memory system compositing of stacked DRAM and off-chip DRAM. This dissertation lists our research results on the above three mentioned challenges in order to optimize the memory system for high efficiency in computing clusters. Details are as follows: To address low row buffer utilization caused by row buffer interference, we propose Row Buffer Cache (RBC) architecture to efficiently mitigate row buffer interference overheads. At the core of the RBC architecture, the DRAM pages with good locality are cached and escape from the row buffer interference.Such an RBC architecture significantly reduces the overheads caused by row activation and precharge, thus improves overall system performance and energy efficiency. We evaluate our RBC using SPEC CPU2006 on a DDR4 memory compared to the commodity baseline memory system along with the state-of-art methods, DICE and Bingo. Results show that RBC improves the memory performance by up to 2.24X (16.1% on average) and reduces the overall memory energy by up to 68.2% (23.6% on average) for single-core simulations. For multi-core simulations, RBC increases the performance by up to 1.55X (16.7% on average) and reduces the energy by up to 35.4% (21.3% on average). Comparing with the state-of-art methods, RBC outperforms DICE and Bingo by 8% and 5.1% on average for single-core scenario, and by 10.1% and 4.7% for multi-core scenario. To relax the straggling effect observed in clusters, we aim to speed up straggling work nodes to quicken the overall processing by leveraging exhibited performance variation, and propose StragglerHelper which conveys the memory access characteristics experienced by the forerunner to the stragglers such that stragglers can be sped up due to the accurately informed memory prefetching. A Progress Monitor is deployed to supervise the respective progresses of the work nodes and inform the memory access patterns of forerunner to straggling nodes. Our evaluation results with the SPEC MPI 2007 and BigDataBench on a cluster of 64 work nodes have shown that StragglerHelper is able to improve the execution time of stragglers by up to 99.5% with an average of 61.4%, contributing to an overall improvement of the entire cohort of the cluster by up to 46.7% with an average of 9.9% compared to the baseline cluster. To address the performance difference in the irregular application, we devise a novel method called Similarity-Managed Hybrid Memory System (SM-HMS) to improve the hybrid memory system performance by leveraging the memory access similarity among nodes in a cluster. Within SM-HMS, two techniques are proposed, Memory Access Similarity Measuring and Similarity-based Memory Access Behavior Sharing. To quantify the memory access similarity, memory access behaviors of each node are vectorized, and the distance between two vectors is used as the memory access similarity. The calculated memory access similarity is used to share memory access behaviors precisely across nodes. With the shared memory access behaviors, SM-HMS divides the stacked DRAM into two sections, the sliding window section and the outlier section. The shared memory access behaviors guide the replacement of the sliding window section while the outlier section is managed in the LRU manner. Our evaluation results with a set of irregular applications on various clusters consisting of up to 256 nodes have shown that SM-HMS outperforms the state-of-the-art approaches, Cameo, Chameleon, and Hyrbid2, on job finish time reduction by up to 58.6%, 56.7%, and 31.3%, with 46.1%, 41.6%, and 19.3% on average, respectively. SM-HMS can also achieve up to 98.6% (91.9% on average) of the ideal hybrid memory system performance.
  • Development and Benchmarking of Hermitian and non-Hermitian Methods for Negative Ion Resonances

    Matsika, Spiridoula; Spano, Francis C.; Perdew, John P.; Napolitano, Jim (Temple University. Libraries, 2022)
    Low energy electron (LEE) driven chemistry underpins a wide range of interdisciplinary fields, including radiation biology, redox chemistry, astrochemistry and biomaterial design. A growing interest in the chemistry of LEEs concerns the radiative damage to DNA. Studies have found that LEEs can induce single and double-strand breaks in DNA by forming a negative ion resonance (NIR). These processes are remarkably site-specific and have been utilized to synthesize radiosensitizers, which aid in identifying target cells in hypoxic tumors in radiation therapy. Despite the prevalence of LEE-induced reactions, computational studies of such processes are limited compared to thermal and photochemical reactions. The relative scarcity in computational studies of LEE-induced reactions stems from the difficulties in the theoretical treatment of NIRs. In our work, we report new developments on the application of quantum chemical methods to NIRs. We demonstrate that the combination of approaches developed for resonances with multi reference electronic structure methods enables the computation of various types of NIRs in a single calculation. Additionally, we show that multi-reference methods can also quantify the mixing between NIRs. It is observed that the mixing between resonances can have significant consequences on their lifetimes. We also report the development of a new technique, the continuum remover Feshbach projection operator approach, which uses the conventional methods developed for bound states to characterize resonances. We show that this new approach is straightforward to implement with standard electronic structure packages, it is efficient, and provides promising results.
  • Co-victims of Gun Violence: How Black Women Navigate Spaces of Trauma

    Pearsall, Hamil; Gilbert, Melissa R.; Hayes-Conroy, Allison, 1981-; Levine, Judith Adrienne, 1965- (Temple University. Libraries, 2022)
    This dissertation examines how relatives of gun-violence victims, specifically Black women, move about their environments in the aftermath of sudden and tragic loss. I explore the following research questions: 1) How do Black women, who are co-victims of gun homicide, navigate spaces of trauma? 2) How does the experience of trauma extend into other spaces and spatialities of their lives? 3) What are the social, political, and health implications for Black women with limited mobility who are co-victims of gun homicide? This study draws on a literature synthesis on health geographies, geotrauma, and Black Feminist Geographies, as well as auto-methods, specifically a Black Feminist auto-ethnography (BFA). BFA involves analyzing your own experiences in relation to others in their family and community. My autoethnography of my lived experiences in the neighborhood I grew up in started with the observation of my mother in the aftermath of losing my brother to gun violence in 2012. My dissertation develops a research agenda to theorize how racism, poverty, and trauma compound and how Black women craft survival strategies as they navigate landscapes of trauma. I describe the ways that conventional approaches to understanding gun violence can overlook the layers of trauma and fail to capture the nuances or lived experience of being a co-victim of gun violence. I propose BFA to center and understand the lived experience of co-victims of gun violence and to bear witness to the ways we engage with the world around us while processing the trauma that is carried with us. My autoethnography uncovers key strategies my mother and I used to cope with our loss, especially in the face of institutional failures from the policy. This research points towards a need for better mental health resources for co-victims of gun violence as they process their grief.
  • Employing Organ-on-Chip Technology for the Study of Sepsis and Drug Screening

    Kiani, Mohammad F.; Kilpatrick, Laurie; Pillapakkam, Shriram; Prabhakarpandian, Balabhaskar (Temple University. Libraries, 2022)
    Inflammation is a crucial physiological defense mechanism of the human body to injury or infection. However, dysregulation of the magnitude or duration of inflammation response underlies multiple disease pathologies and may cause organ damage. Sepsis is a severe inflammatory disease now known as a clinical syndrome defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis patients often die of organ failure and the endothelium and neutrophil-endothelial cell (EC) interactions play an active role in the regulation of the systemic inflammatory response. Systemic inflammatory disease often results in alterations in vascular endothelium barrier function, increased permeability, excessive leukocyte trafficking, and reactive oxygen species production, leading to organ damage. While neutrophils are critical to host defense, neutrophil dysregulation has a critical role in organ damage through release of proteases, neutrophil extracellular traps (NETs), and reactive oxygen species (ROS), which can damage host tissue leading to organ failure. To date therapeutic approaches are largely supportive and therapeutics targeting endothelium inflammation and immune cell dysregulation are urgently needed. However, strong concerns regarding the level of phenotypic heterogeneity of microvascular ECs between different organs have been expressed. Microvascular EC heterogeneity in different organs and organ-specific variations in EC structure and function are regulated by intrinsic signals that are differentially expressed across organs and species, as a result of which neutrophil recruitment to discrete organs may be regulated differently. In addition, therapeutic development is hindered due to the heterogeneous nature of sepsis and the presence of multiple distinct immune phenotypes that can impact function and response to infection. In fact, clinically sepsis is a heterogeneous syndrome and diagnosis is complicated due to the broad spectrum of non-specific clinical features. Patients with similar clinical symptoms can be associated with distinct immune cell phenotypes ranging from excessive immune activation to immunosuppression, which means different therapeutics are required. In this work, the morphological and functional variations of differently originated microvascular endothelium are discussed and how these variances affect systemic function in response to inflammation. Emerging in vivo and in vitro models and techniques including microphysiological devices, proteomics, and RNA-Sequencing used to study the cellular and molecular heterogeneity of endothelium from different organs will also be discussed. Our group have developed a novel Organ-on-Chip, the biomimetic microfluidic assay (bMFA) that mimics physiological conditions, allowing us to observe real-time neutrophil-endothelial interactions, including rolling, adhesion, and migration, and to study endothelial barrier function under physiologically relevant conditions including the effect of shear forces and vascular geometry. The bMFA enables the quantification of leukocyte-EC interactions, including rolling velocity, number of adhered leukocytes in response to different shear rates, number of migrated leukocytes, EC permeability, adhesion molecule expression and other important variables. Furthermore, by using human related samples, such as human ECs and leukocytes, bMFA provides a tool for rapid screening of potential therapeutics to increase their clinical translatability. In this work, a protocol was developed to study endothelium function and neutrophil-endothelial interactions during inflammation in the bMFA. Lastly, to develop targeted therapeutics, immunophenotyping is needed to identify distinct immune cell functional phenotypes. We have developed a methodology to classify ICU sepsis patients into three phenotypes using patient data, Organ-on-Chip-based neutrophil functional analysis and proteomics. The findings of the study will help identify different sepsis patient immune-phenotypes and personalize treatment accordingly.
  • Developing P-Stereogenic Phosphine Ligand for Transition Metal Catalyzed Asymmetric Hydrogenation

    Dobereiner, Graham; Kim, Daniel K.; Sieburth, Scott McNeill; Zhang, Xumu (Temple University. Libraries, 2022)
    This dissertation focusses on the discussion of how empirical ligand design works on the development of chiral pincer ligands in the field of asymmetric hydrogenation. Although the design art of bisphosphine ligands was well-established, this empirical guide for pincer ligand design is still ambiguous. Developing a ligand design guide based on the nature of metals enables synthetic chemists to improve the catalytic performance without investing large numbers of time, develop highly efficient catalysts for industrial uses, or explore new areas and mechanistic insights. Learning from the history of chiral pincer ligand development, over 14 categories of pincer ligands were reported according to the coordinating atoms by the time that this dissertation was prepared. Firstly, the ligand design and relevant catalytic performance of different ligand categories were summarized and discussed in prevalent noble metal catalysis such as Ru(II), Ir(III). Based on the nature of Fe(II) with respect to noble metals, a novel PNP-type ligand HengPNP (L) was designed and successfully synthesized. Empirical design perspectives were discussed, and the ligand was characterized by NMR, HRMS. Its corresponding Fe(II) complex was studied by X-ray crystallographic technique. However, the Fe(II) carbonyl complex was thermodynamically unstable under decent pressure. To better understand the catalytic performance and enantioselectivity of HengPNP(L), its corresponding Ir(III) complex was employed in the asymmetric hydrogenation of various ketone substrates. A C-H bond activation Ir(III) compound was successfully isolated. The Ir(III)/HengPNP was efficient on the asymmetric hydrogenation of orthosubstituted benzophenones with excellent ee and up to 500 TON. The catalyst was superior on the hydrogenation of bis-ortho-substituted benzophenones, excellent ee was achieved over the state-of-the-art Ir/f-amphox. DFT studies was conducted to shed light on the enantio-induction model of Ir/HengPNP. A novel enantio-induction mechanism was established-the change of rotation energy of ketone substrate under the steric pressure from rigid Ir/HengPNP, was responsible for the enantioselectivity. IrH/NH bifunctional mechanism was proposed for this protocol.

    Nagar, Swati; Fassihi, Reza; Barrero, Carlos; Bode, Chris (Temple University. Libraries, 2022)
    The oral route of administration is the most widely used mode of drug administration due to advantages such as the convenience of oral drug administration, patient choice, cost-effectiveness, and ease of generating oral dosage forms on a large scale. How effectively an oral drug is absorbed and made accessible to the target organ depends on a variety of factors. Poor absorption from the absorption site, excessive metabolism in the gut and liver, and pharmacokinetic drug-drug (PK-DDI) interactions can all contribute to inadequate therapy. The PK-DDI may result in greater than anticipated bioavailability and toxicity due to irreversible enzyme inhibition including time-dependent inactivation (TDI) of the intestinal enzymes.There are different in vitro models available to predict the fraction escaping gut metabolism (Fg), which is a major determinant of intestinal bioavailability. On the other hand, using pre-clinical species, Fg can be extrapolated in humans using allometric scaling, but there has been significant discordance due to the variable intestinal metabolism in humans vs. pre-clinical species. A number of absorption models have been developed over the years to predict oral drug absorption, and intestinal TDI can be incorporated into many of those models. In this study, the continuous intestinal absorption model has been refined, including the intestinal metabolism model, to predict the oral absorption of midazolam and nicardipine in both humans and rats. This absorption model was also used to predict the Fg of these drugs in those two species. The in vitro metabolic characteristics of the model drugs were investigated using both human and rat microsomes. The kinetic profiles of their metabolic conversion in rats and humans were developed using numerical techniques. The continuous absorption model explains how drug concentration changes with time and distance. A physiologically based pharmacokinetic (PBPK) model describes the intestine. The physiological inputs to the model, as well as the structure of the gastrointestinal tract, vary depending on the species. Rats and humans have different lengths of the small intestine's regions, such as the jejunum, and absorptive surface area amplifiers, such as the villi and microvilli. Along with the metabolic characteristics established through in vitro metabolic investigations, physiological aspects (applied to both rats and humans) and physicochemical drug characteristics were also added to the model. To estimate the absorption characteristics of midazolam and nicardipine, this model was further connected to the traditional compartmental model that represents the rest of the body. Chapter one details the background and importance concerning this project, along with the hypothesis and goals. Chapter two involves developing and validating bioanalytical methods for the drugs of interest. Chapters three and four detail the in vitro metabolic studies in rat and human microsomes (both intestinal and liver). Chapter five represents the TDI studies which were finally excluded from the absorption modeling in this thesis. Finally, chapter six illustrates the prediction of the oral PK profile of midazolam and nicardipine in rats and humans, rendering predicted values of Fg of these drugs in both species. Finally, chapter seven presents the significance, summary, and some directions to take this research further down the future.
  • Examining the neural underpinnings of experienced and described information in adolescent risk-taking

    Chein, Jason M.; Venkatraman, Vinod; Murty, Vishnu; Steinberg, Laurence D., 1952-; Jarcho, Johanna; Lauharatanahirun, Nina (Temple University. Libraries, 2022)
    Adolescence is a unique developmental period where substantial brain development and social independence can result in higher risk-taking behavior. Researchers have spent the last several decades trying to understand at a neurological level why adolescents are more likely to take risks that often have extreme consequences (e.g., car accidents, drug use, etc.). The resulting research has found mixed and often inconsistent findings and scientists have posited that this could be due to differences in experimental tasks; where some are more description-based (e.g., Wheel of Fortune tasks) and others are more experience-based (e.g., Stop Signal tasks). Research examining the way adults learn about risk reveals that individuals make different decisions when information is learned via description or experience – a phenomenon known as the Description-Experience Gap. The present work aims to bridge research in adolescent development and judgement and decision-making to identify the neural processes associated with the Description-Experience gap in adolescents and adults. Across two studies, I examined the neural mechanisms associated with learning via description and experience in adolescents and adults and their subsequent impact on risky choice to find that adolescents and adults utilize information from description and experience differently. In adults, similar neural mechanisms involved with memory and deliberation are implicated at different points of the decision process. Adolescents displayed distinct neural activation associated with risk-taking and reward sensitivity when learning via experience. Both studies demonstrate the significance of memory and learning-relevant processes in risk-taking across development.
  • The Role of Mitochondrial GRK2 in the Pathogenesis and Progression of Heart Failure

    Koch, Walter J.; Kishore, Raj; Tilley, Douglas G.; Mohsin, Sadia; Sato, Priscila (Temple University. Libraries, 2022)
    Rationale: G protein-coupled receptor (GPCR) kinases (GRKs) are important regulators of cardiac function whose primary role is the phosphorylation of GPCRs and attenuation of downstream signaling, and GRK2 is upregulated after cardiac stress, injury, and during heart failure (HF). Recent studies have identified novel non-GPCR roles for GRKs such as cytoskeletal assembly, insulin signaling, fibrosis and pro-death signaling. One of the most compelling discoveries regarding novel roles of GRK2 in HF pathogenesis is its mitochondrial translocation (mtGRK2) following cardiac injury, which is associated with increased ROS production, decreased FA metabolic oxygen consumption, and pro-death signaling. Moreover, this localization is dependent on phosphorylation of serine 670 (S670) by kinases such as ERK1/2. Of note, expression of a GRK2 C-terminus peptide, βARKct, which contains S670 but no kinase domain or activity, is cardioprotective following injury in part due to inhibition of endogenous mtGRK2. This is significant because growing evidence demonstrates that cardiomyocyte metabolism is regulated by levels and activities of individual mitochondrial proteins Objective: This study sought to identify mitochondrial proteins which GRK2 interacts with either basally or after injury- or stress-induced translocation, and to determine whether functional regulation of mitochondrial function via phosphorylation of these proteins contributes to the phenomenon of bioenergetic defects during the development of HF. Methods and Results: Co-immunoprecipitation of GRK2 in vitro from primary ventricular cardiomyocytes and a human transformed cardiomyocyte-derived cell line was followed by liquid-chromatography mass-spectroscopy identification of all GRK2- interacting proteins. We followed this with proteomics analysis using DAVID and iv Ingenuity software to identify main pathways altered by GRK2 during stress or injury, focusing on mitochondrial dysfunction which revealed that GRK2 interacts with all major components of the electron transport chain (ETC). Using recombinant proteins as well as in vitro and in vivo models of myocardial infarction (MI), we demonstrate that GRK2 is able to phosphorylate the catalytic barrel of mitochondrial ATP synthase (complex V). Moreover, reduction of GRK2 levels in vivo using a GRK2 knockdown mouse model appears to protect against injury-induced bioenergetic deficits, whereas increased GRK2 levels in a transgenic GRK2 overexpression mouse model reveals both baseline deficits in ATP production as well as worsened post-MI outcomes. Conclusions: These collective data highlight the significance of the mitochondrial GRK2 interactome as a driver of cardiac bioenergetic deficits, particularly as a response to MI injury which progresses to HF. Given the current lack of effective HF treatments, this highly novel mechanism of GRK2 regulation of the mitochondrial ETC emphasizes the need for GRK2-targeting therapies for treating HF.

    Grace, Martin Francis, 1958-; Viswanathan, Krupa S.; Ellis, Cameron M.; Mao, Connie X. (Temple University. Libraries, 2022)
    Three waves of tort reform occurred during mid-1970s, mid-1980s and early 2000s to deal with the liability “crises”. The inflationary pressures drove up the medical costs and social inflation pushed up the damage awards size, which led to the tort reform waves. We could see a potential today when the inflation continues to increase. Tort reforms have been widely studied for its impact on the litigation costs and benefits, through which physicians and insurers’ liability burden can be affected. While the liability markets have been relatively calm recently, legislative and academic debates over the efficacy of tort reforms and how they influence litigation behavior is not yet resolved. Whether tort reforms work to reduce the medical expenses and exert spillover effect on other insurance line market needs to be tested. A thorough analysis of tort reforms effect will benefit policymakers, regulators, insurers, and physicians and patients. This dissertation consists of three chapters to study how tort reforms affect the insurance markets, with a focus on health insurance markets. Chapter 1 assesses whether the effect of tort reform on the healthcare expenditures depends on the contract conditions under which physicians are paid for their professional services. Chapter 2 explores the potential for tort reforms to improve health insurers’ performance by boosting their efficiency. Chapter 3 looks at other types of state reforms and policies influencing liability costs to assess the effect on both medical liability and health insurance markets.

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