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Insights into the Racemization and Asymmetric Synthesis of Chiral Organofluorines and Advances in Chiroptical Sensing Methodology
No full textPh.D.The role of chirality within drug development underscores the importance of introducing novel asymmetric synthetic routes for complex, multifunctional compounds. This
comes with many challenges often involving the need to control regioselectivity,
diastereoselectivity, and enantioselectivity while maintaining high yields and broad functional
group tolerance. While this is no trivial task, the development of high-throughput
experimentation (HTE) allows many reactions to be carried out in parallel, thus streamlining
asymmetric reaction development. However, the determination of absolute configuration and
enantiopurity of chiral products often becomes a bottleneck in this process as traditional
analytical tools such as chiral HPLC are serial techniques, allowing only one sample to be run
at a time. Circular dichroism (CD) spectroscopy is amenable to HTE and overcomes those
challenges by enabling rapid determination of enantiomeric excess (ee) and absolute
configuration, in turn reducing waste production and increasing efficiency. This thesis presents
novel strategies for both asymmetric reaction development and high-throughput analysis of a
wide variety of chiral compounds to bridge the gap between stereoselective synthesis and
subsequent analysis.
Chiroptical sensing of alcohols is often difficult due to their low nucleophilicity. An
organocatalytic reaction using 4-dimethylaminopyridine (DMAP) was developed with an
achiral isocyanate probe to carry out quantitative sensing of challenging aromatic and aliphatic
alcohols and diols. The inexpensive probe also reacts quickly with amines and amino acids to
induce strong UV and CD inductions above 300 nm. The applicability of this assay was
demonstrated by accurate determination of absolute configuration, ee, and concentration of
various samples containing phenylethylamine.
To expand the scope of CD sensing beyond traditionally privileged functional groups,
an organometallic assay was developed leveraging η6-complex formation between chiral arenes
and a Ru(II) piano stool complex. The “click-like” η6-formation occurs with arenes within
minutes via irreversible acetonitrile displacement and enables sensing of a wide range of chiral
analytes, including the first examples of CD sensing for aromatic tertiary amines, esters, and
lactones. Additionally, this methodology was successfully applied in the chromatography-free
analysis of an asymmetric epoxidation reaction.
The general impact of fluorinated chiral compounds in the life sciences has stimulated
considerable interest in their synthesis and unique properties. The stereochemical integrity of
organofluorines, however, is poorly understood and methods to understand their susceptibility
to racemization would aid greatly in the development of dynamic kinetic resolution protocols
and new asymmetric reactions. To this end, the enantioseparation and racemization of 2-aryl-2-fluoronitriles and 3-fluorooxindoles was carried out using chiral HPLC. The configurational
stability of these compounds was evaluated under a variety of conditions to understand reaction
kinetics and substitution effects.
Due to the significance of fluorinated pharmaceuticals, a three-component asymmetric
carbofluorination of gem-difluoroalkenes was developed utilizing an inexpensive alkali metal
fluoride as the nucleophilic fluoride source. The catalytic protocol developed overcomes
challenges with competing β-fluoride elimination and stereocontrol. The reaction proceeds
under mild and stoichiometric conditions to yield difunctionalized products with good yields
and excellent enantioselectivities
“Today the Mind is Not Part of the Weather”: The Negations of Wallace Stevens
No full textM.A.From his earliest poems to his last, negation proves to be a consistently effective tool for Wallace Stevens to communicate a particular poetical aesthetic. My research positions Stevens’s negations within the academic discourse of his metapoetry and his life-long occupation with the struggle between the human imagination and external reality. This thesis reveals how Stevensuses poetic negation as a form of “decreation” to foster a sense of literary singularity in his early poems, only to turn negation against the poetic act itself in his later career
Intrinsic and Extrinsic Effects on Excitonic Emmissions in Monolayer Transition Metal Dichalcogenides for Next Generation Optoelectronic Applications
No full textPh.D.Monolayer transition metal dichalcogenides (TMDs) like WS2 and MoS2 have unique light-matter interactions due to quantum confinement and reduced dielectric screening. These ultra-thin materials are semiconductors with a direct band gap in the visible regime. Upon illumination, electrons and holes are excited and are strongly bound to each other forming an exciton. When the electron and hole of an exciton recombine, light is emitted. The emissions from excitons unveil a complex family of neutral and charged excitons which are highly sensitive to intrinsic and extrinsic factors including the population, temperature, material impurities, molecular adsorbents, and electrostatic gating. In this work we develop a methodology to explain the origin of complex spectral features in the photoluminescence spectrum of TMDs
UN Peacekeeping Operations: Assessing the Effect of the Presence of the United Nations Organization Mission in the Democratic Republic of the Congo (MONUC) and the United Nations Organization Stabilization Mission in the Democratic Republic of the Congo (MONUSCO) on the Number of Civilian Fatalities Perpetrated by the Lord’s Resistance Army (LRA) in the Democratic Republic of the Congo
No full textM.P.P.Regional instability due to armed group proliferation remains a significant barrier to the realization of socio-economic development and improved quality of life in many sub-Saharan African (SSA) countries. Often, due to weak governing institutions, impunity, poor rule of law, and limited state capacity to deliver public goods and services, countries like the Democratic Republic of the Congo (DRC) develop ungoverned spaces that allow for the expansion of armed non-state actors and attacks against civilians. Ethnically and politically motivated attacks by various armed actors have seen the displacement and death of millions of Africans to date. Despite norms like the Responsibility to Protect and humanitarian laws governing the use of force, weakened state capacity often sees states relying on international actors such as the United Nations as a source of security delivery. The development and maintenance of peacekeeping operations (PKOs) on the African continent has produced mixed results and perceptions of their effectiveness in implementing their United Nations (UN) mandates—notably, the responsibility of PKOs to protect civilians from ongoing violence. Recent calls by countries like Mali and the DRC for UN peacekeepers to leave their countries have raised questions on the effectiveness of UN peacekeepers in quelling insecurity and protecting civilians. However, rushed withdrawals without substantive state capacity building run the risk of increasing the already significant security vacuum present. Poor peacekeeping performance may leave opportunities for regional actors to increase collaborative efforts to eradicate armed violence. Using data from The Armed Conflict Location & Event Data Project (ACLED) on the Lord’s Resistance Army (LRA) attacks against civilians and the International Institute of Peace Peacekeeping Database dataset on UN troops, I examine the relationship between UN peacekeeping and armed group violence in Sub-Saharan Africa by analyzing the country context of the DRC and its most prolific terrorist group the Lord’s Resistance Army from 2005 to 2018. The presence of MONUC and MONUSCO peacekeepers was estimated to produce marginal increases in the total number of civilian fatalities caused by the Lord’s Resistance Army annually across the models assessed, however these results were not significant. Further breakdown by peacekeeper type produced mixed results of some marginal increases and decreases in the expected number of civilian fatalities caused by the LRA. Controlling for the MONUC mission indicates that the MONUSCO peacekeepers may have improved civilian safety. However, a lack of statistical significance of the values produced prevents a clear indication of MONUC/MONUSCO peacekeeper efficiency in protecting civilians. Further research is needed to establish a clear relationship between MONUC/MONUSCO peacekeeper presence on the number of civilian fatalities attributed to the Lord’s Resistance Army
Patients and healthcare workers’ preferences for using smart lockers in accessing and dispensing chronic disease medication in Nigeria: Findings from a descriptive cross-sectional study
No full textCenter for Global Health Practice and ImpactThe use of smart locker technology has been beneficial for patients with chronic diseases who require regular medication and face challenges accessing healthcare facilities due to distance, time, or mobility issues. This study aimed to assess preferences for utilizing Smart Lockers in accessing and dispensing chronic disease medication among healthcare workers (HCWs) and patients in Nigeria. A descriptive cross-sectional survey was conducted between November 8th and December 4th, 2021, across secondary healthcare facilities in five states of Adamawa, Akwa Ibom, Cross River, Benue, and Niger. Among 1,133 participants included in the analysis, 405 were HCWs and 728 were patients with chronic illnesses. Descriptive statistics, including frequencies and percentages, were used to summarize the data, while chi-square tests were employed to assess significant differences between healthcare workers (HCWs) and patients. Results indicated a strong preference among both HCWs and patients for one-on-one counseling as the preferred method for orientating patients on using Smart Lockers, with 53.8% of HCWs and 58.1% of patients expressing this preference (p = 0.25). Additionally, there was a shared preference for hospitals or clinics as secure locations for Smart Lockers, with 68.9% of HCWs and 71.6% of patients preferring this option (p < 0.05). The majority of participants favored receiving notification of drug delivery via phone call, with 49.1% of HCWs and 48.8% of patients expressing this preference (p = 0.63). There was a significant difference in preferences for access hours, the majority (HCWs: 65.4% and patients: 52.6%) favored 24-hour access (p < 0.05). Participants identified patients with HIV within the age range of 18–40 as the most suitable population to benefit from using Smart Lockers for medication dispensing. These findings offer insights into healthcare policies aimed at enhancing medication access and adherence among patients with chronic diseases in Nigeria. The development of models for using smart lockers to dispense chronic disease medications to chronically ill persons in Nigeria and other populations is recommended
The Effect of Alternative Methods of Discipline on High School Suspension Rates: Evidence from the Maryland Positive Behavioral Intervention Supports Initiative
No full textM.P.P.This thesis examines Positive Behavioral Intervention Supports (PBIS) as an alternative method to harsh methods of school discipline. PBIS aims to manage conflict by repairing harm, restoring relationships, and developing community. These practices have been found to improve student behavior and connectedness by helping them develop closer bonds with their peers and teachers, minimize repeat negative behavior, and allow students to reintegrate into the school community with ease. In the late 1990s, PBIS Maryland was created to help schools in Maryland build the capacity to adopt and sustain a multi-tiered framework for implementing evidence-based PBIS practices. This paper uses a fixed effects analysis to assess the efficacy of the PBIS Maryland Initiative on high school suspension rates. The analysis did not detect a relationship between PBIS training and total suspension rates, but did find that PBIS intervention is more effective in reducing suspensions in schools with higher populations of black students
Impact of Virtual Mental Health Visits, with Home Visitation, on Depressive Symptoms in Rural Peripartum Individuals
No full textD.N.P.Mental health conditions are the most common complication during the peripartum. Mental health services provided via telehealth are shown to be a viable option when face-to-face services are not available. Those living in rural areas experience a higher burden of depression with less access to mental and behavioral health resources. This project was an evaluation of a pilot project looking at the impact of virtual mental health visits, with home visitation, on depressive symptoms in rural peripartum individuals. The pilot took place in a home visiting population in the rural mountainous southwestern United States. The primary aim was to see how the pilot impacted client mental health. Two secondary aims looked at the impact on access to mental health services and the role of demographics on the use of mental health services. Client satisfaction was assessed. Forty-four first-time mothers were analyzed showing no statistically significant relationship between the virtual mental health services and client PHQ-9 and GAD-7 scores (p=.904 and p=.923, respectively). Comparing rates by year, counseling offered increased by 19.4 percentage points from 2022 to 2023, but this was not statistically significant, X2(1) = 2.4, p = .124. There was a 58.3 percentage point increase in offering online services, a statistically significant increase, X2(1) = 12.0,
The Privatization of American Public Health Insurance: A Comparative Analysis of Obstetric Outcomes and Costs in Medicaid Managed Care Versus Private Insurance
No full textM.S.Over two-thirds of Medicaid beneficiaries have received assistance from Managed Care Organizations (MCOs), mostly for-profit entities operating under a capitated payment model in 2024. State Medicaid programs have widely adopted this Medicaid Managed Care (MMC) model, embracing it as the ultimate “magic bullet” for reducing Medicaid costs and improving patient outcomes. This study scrutinized these assumptions by evaluating whether this marketplace-based framework––traditionally effective for privately insured individuals who typically have higher purchasing power––is equally suitable for Medicaid patients, who often have higher health risks but minimal purchasing power. Using 2020-2021 obstetric data from Washington Hospital Center in DC, this study assessed childbirth outcomes and associated costs across these two patient groups, given their unified for-profit, capitated framework. The findings reveal that Medicaid pregnant individuals had lengthier inpatient stays and higher rates of preterm births and low birth weight, as well as higher healthcare costs compared to their privately insured counterparts. Surprisingly, they also had fewer documented cases of more common labor and delivery complications, such as perineal tears and non-assuring fetal status. The results suggest that despite its success with private insurance demographics, the managed care model may not adequately address the complex needs of Medicaid’s high-risk, high-need profile, potentially requiring a reevaluation of its application within the sphere of public health insurance
What Is the Relationship Between State-Level Gun Ownership and Fatal Police Encounters?
No full textM.P.P.More than 1,000 people are killed by law enforcement each year in the United States and the rate of fatal police shootings exceeds that of most wealthy democracies. This study examines the relationship between gun ownership and fatal police shootings using state-level cross-sectional data spanning 2005 to 2016. The study expands on previous research by utilizing a new measure of gun ownership, focusing on fatal police encounters as well as fatal police shootings, extending the time period of analysis, and including a measure of police spending to assess the relationship between departmental funding and fatal police encounters. I find a positive association between gun ownership and fatal police encounters. Specifically, between 2008 and 2016, I find that a one standard deviation increase in the state gun ownership rate is associated with a 19-23% increase in the rate of fatal police encounters. This relationship is consistent in analyses that use fatal police shootings instead of fatal police encounters. These results confirm and extend prior research findings of a relationship between gun ownership and fatal police shootings at the state level. As states consider policies to mitigate homicides, suicides, and mass shootings, it is critical for legislators to note the potential impact of expansions or restrictions of gun ownership on police encounters. Additional research is needed to more fully examine this relationship and explore the effects of gun ownership policies on other policing outcomes