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THE ROLE OF SOIL MOISTURE STATE ON THE INCIDENCE OF SUMMER MESOSCALE CONVECTIVE SYSTEMS IN THE U.S. GREAT PLAINS
Get PDFMesoscale convective systems (MCS) are known to develop in strongly-forced synoptic environments, but recent work has shown that summer MCS events in the U.S. Great Plains can occur in weakly-forced synoptic environments, and convection in this case may be triggered by anomalous soil moisture (SM) conditions. Using an MCS database covering the contiguous U.S. east of the Rocky Mountains in boreal summers 2004–17, this dissertation aims to identify the SM conditions associated with summertime MCS initiations in the U.S. Great Plains, and to identify a mechanism of interaction between the SM state and MCS initiation through the lens of local land-atmosphere (L-A) coupling. MCS events that occur in weakly-forced synoptic environments are isolated using the Convective Triggering Potential and Low-Level Humidity Index (CTP-HI_low), and their SM conditions are evaluated centered on the mean initiation position of a 5° X 5° domain. At larger scales [O(100) km], soil moisture heterogeneity, where anomalously dry soils (anomalously wet soils) are located southwest (northeast) of the initiation point, is associated with MCS initiation. These dry and wet soils set up a surface temperature gradient, which is hypothesized to produce a surface pressure gradient that drives a near-surface wind perturbation with convergence and upward motion to stimulate convection. To test this hypothetical mechanism, numerical experiments are performed with the Weather Research and Forecasting (WRF) model by imposing idealized, exaggerated SM perturbations (PB) having varying organizations and alignments to the near-surface wind. The MCS initiation locations are used as the center point for a 5° X 5° domain where SM is changed, with five total SM PB. A storm-centered analysis of SM showed that PB-1, where SM is uniformly set to a near-wilting point in the experiment domain, was the only experiment that consisted of organized heterogeneity [O(100)km], structured as significantly drier soils in the southwest transitioning to wetter soils in the northeast. Further analyses showed the PB-1 experiment demonstrated the largest thermodynamic and dynamic response, where the mechanism of interaction was driven by SM values in the transitional regime promoting strong local L-A coupling (these SM values are associated with smaller evaporative fraction and larger sensible heat flux values that influenced the growth of the PBLH), and the spatial SM gradient aligned with the near-surface wind produced additional uplift to generate convection. While the PB-1 experiment was intended to evaluate the response to homogeneously dry SM, an artifact of imposition of the SM perturbation in the model domain set up a large dry-to-wet SM gradient along the eastern and northern edges of the PB area, and MCS initiations were subsequently preferred over those transition zones. These cumulative findings are similar to the previous results in the Sahel that suggest SM heterogeneity can drive MCS initiation, with meso-β circulations related to near-surface variable fluctuations as the main mechanism of interaction
Napoleon and Daru: The Forging of an Ironclad Partnership
Get PDFTypically, the image of an eighteenth-century battle depicts brave soldiers marching shoulder to shoulder to the sound of drums and fifes. Yet, this picture, idealized in thousands of books and films, reflects just one dimension of the art of waging war. Behind the scenes, weapons and ammunition had to be produced and distributed, food and fodder shipped to regiments on the march, troops had to be paid, and convoys organized with medical supplies and equipment. Although recordkeeping has enabled experts to compare opposing armies in relation to the number of troops, cannons, or horses as well as in terms of the volume and quality of nourishment or general health, it is remarkable that logistics, a vital dimension of warfare, has been underappreciated by publishers and researchers. John Lynn, editor of the book Feeding Mars, attributes this to the apparent lack of interest in the subject manifested by readers.
Moonlight Over Cedar Creek and Other Stories of Women during the Civil War in Virginia
No full textThough often overlooked, women were on the front lines of the American Civil War in Virginia. They served as vivandieres (women attached to regiments), soldiers disguised in men’s garments, laborers in military camps, nurses, spies, and more. The stories in this thesis explore different experiences and perspectives of women in the Civil War through the common threads of survival, sisterhood, historical preservation, family, and devotion. In this collection, preservationists struggle to keep George Washington’s legacy neutral during a fraught time of division; a military wife searches for her wounded husband in enemy territory; women disguised as male soldiers contemplate desertion; plantation owners must learn how to cook for themselves when their enslaved workers flee to freedom; an army medic fights to keep a promise during a bloody battle; and four years of war have harsh repercussions for two young sisters whose city becomes the Confederate capital.This thesis has been embargoed for 10 years. It will not be available until December 2032 at the earliest
Brilacidin as a Broad-Spectrum Inhibitor of Enveloped, Acutely Infectious Viruses
Get PDFThis thesis has been embargoed for 2 years. It will be available for access in November 2023 at the earliest.Rift Valley Fever virus (RVFV) is a Bunyavirus known to cause severe disease in livestock. Its zoonotic capability makes it a serious threat as it has become endemic in many parts of the world. While primarily spread through Aedes and Culex mosquitos, it can also be transmitted via aerosol and direct contact with infected bodily fluids. In humans it is known to cause hemorrhagic fever and liver failure. There are currently no FDA approved treatments for RVFV, making it an area of serious concern for the development and implementation of novel therapeutics. In this investigation Brilacidin (BRL), a defensin mimetic, was tested against RVFV among other viruses such as Sindbis (SINV) and an Echovirus. BRL was previously designed for antibiotic-resistant bacteria and its amphipathic nature enables it to disrupt membranes. It has been shown to be effective on both gram-positive and gram-negative bacteria, including MRSA. This work on bacteria has since been expanded to enveloped viruses such as SARS-COV-2, the causative agent of COVID-19. RVFV was tested in Human small airway epithelial cells (HSAECs) via plaque assay, and then this was repeated in other cell lines including Huh7s and HepG2s. Cytotoxicity analyses were conducted to determine cell viability when BRL was applied to the cells. Through direct viral treatment, a significant decrease was seen in viral load, that was not seen with pre-treatment and post-treatment of the cells. Cell viability was also tested for, demonstrating that the presence of BRL aids cell survival. This work was then expanded out to Sindbis virus (SINV), and an Echovirus. The Echovirus served as a negative control due to its unenveloped nature. In both viruses, BRL was once again found to be effective at reducing viral titer.2023-11-2
DNA Origami as a Technique to Build Virus Engulfing Shell Complexes
Get PDFDeoxyribonucleic acid (DNA) is the molecule used by all living organisms to carry their genetic information and pass on their heritable traits between generations. DNA molecules have also other intrinsic properties that make them promising building blocks to assemble novel bio-nanomaterial. Within the realm of nanotechnology exists a subfield known as structural DNA nanotechnology that uses the DNA molecule as a building block to precisely assemble nanostructures with prescribed features. DNA origami is one of the most versatile techniques developed in the DNA nanotechnology field. Indeed, DNA origami is an assembly technique, which utilizes a single stranded DNA scaffold that can be hybridized by many short oligonucleotides called staple strands to fold the nanoparticle into any desired shape in the 10 to 100 nm scale. These nanoparticles can be made into any shapes including 2D arrays and 3D nanoparticles that can be used for drug delivery, vaccine development, and viral capture among other applications. In addition, DNA is also easily functionalized with organic and inorganic molecules such as fluorophores and targeting moieties, which can be useful in visualization or tracking. The focus of this research is to leverage the advantages of DNA origami to design and assemble nanoparticles capable of enveloping viruses based on their respective capsid’s geometry and glycoprotein organization as a novel viral therapy technique. In this investigation, the rabies virus is used as a model of target. If the structural parameters of the array and the organization of the capturing moieties match with those of the viral capsid, then the DNA array nanoparticles should possess the capacity to efficiently bind to the Rabies Virus. Here, I designed and synthetized multiple nanoscale designs that meet the viral parameters of the rabies virus using the Tiamat software. Agarose gel electrophoresis was used to validate proper folding of the DNA origami nanoparticles. In a second time, gold beads modified with streptavidin was used to mimic the virus and serve as proof of principle with biotinylated DNA nanoarrays. The binding was validated with dynamic light scattering (DLS) and zeta potential measurements that show increase in size and change in the surface charge matching with coverage with DNA. All of these tests indicated that the origami nanoparticle had successfully bound to the gold-streptavidin complex and is ready to be used with viral capsids
Disrespectful Female: The Problem with Calling Women Females
Get PDFThe work done in this paper seeks to critically look at the usage of the word “female” as a replacement word for “woman” in a way that points out the inherent disrespect that is ingrained into the usage of that word. Utilizing Critical Discourse Analysis influenced by feminist theory, queer theory, and critical race theory frameworks, I hope to better understand how and why the word “female” has come to denote such disrespect while doing so in a more covert fashion than typical insults tend to do
Health Professionals as Advocates for Climate and Health Solutions: The Influence of Social Norms on Health Professional Engagement in and Public Support for Climate Advocacy
Get PDFTo address climate change, climate-friendly actions and policies must be implemented. As highly trusted sources of information about climate change and health, health professionals are poised to have an exceptionally important impact on institutional climate-friendly actions and policies through advocacy. Despite this positionality, efforts to engage health professionals in climate advocacy are relatively new and little is yet known about how to do so effectively or how the public perceives such engagement. I conducted a survey experiment with medical societies (Study 1) and field experiments with advocacy organizations (Study 2) to investigate if social normative appeals—both descriptive and dynamic—help encourage health professionals to engage in climate advocacy. I also conducted a survey experiment with the general public (Study 3) to examine if the presence of normative information and the type of advocacy—educating community members, advocating with policymakers, and civil disobedience—influences public perceptions of climate advocacy. In Studies 1 and 2, I found mixed results surrounding the effectiveness of social normative appeals to engage health professionals in climate advocacy, although descriptive normative appeals showed the most promise. InStudy 3, I found that trust in health professionals as a source of information about human health and climate change increased after exposure to the messages, with trust increasing for all conditions except the no norm and civil disobedience condition. Normative information had a main effect on perceptions of health professionals’ credibility, and the type of advocacy had a main effect on perceptions of the acceptability and appropriateness of the action taken, but no interaction effect was found between the two. Together, the findings provide insights into the use of normative appeals for advocacy engagement, deepens current understanding of how the public perceives climate advocacy, and provides guidance for practitioners looking to further engage people in advocacy for climate change and health solutions
Interactions of PGLa Peptides with Bacterial Membranes
Get PDFPGLA is an antimicrobial peptide (AMP) isolated from the skin of the Xenopus laevis frog. AMPs are being studied as a potential new source of new antibiotics, which are needed because of problems with drug resistant bacteria. PGLA has been shown to be effective against many bacteria and fungi, but it is also hemolytic in high concentrations. It appears that PGLA works by increasing the permeability of the membrane, although the exact mechanism remains unknown. To gain molecular insights into PGLa cytotoxicity, we used molecular dynamics simulations to probe binding of PGLa peptides to microbial-like membranes. Our objectives were three-fold. First, to determine the best method for sampling peptide-bilayer interactions, we compared replica exchange molecular dynamics with solute tempering (REST) against replica exchange molecular dynamics with hybrid tempering (REHT), which had never before been used for peptide membrane interactions. Specifically, we performed REST and REHT simulations of PGLa monomers binding to a simplified mimic of a bacterial membrane (DMPC-DMPG). We found that REHT was significantly more efficient than standard REST. Although REHT required 66% more replicas (20 vs. 12), we estimated that it would take between 2 and 3 times longer to equilibrate the simulation system using REST compared to REHT (Bowers, Lockhart, and Klimov, 2023). As a result, using the same computer resources, it would require about 50% longer to equilibrate using REST than REHT. Although REST did not equilibrate the system in 400ns, it did map the same bimodal binding mechanism but not in the same weights. REST would eventually generate an equilibrated ensemble of structures after sufficiently long simulation times. Second, using REHT we exhaustively studied the mechanism of PGLa monomer binding to DMPC/DMPG bilayer. These simulations utilized low peptide:lipid (P:L) ratio blocking, by design, PGLa aggregation. We found that the binding free energy landscape identifies two major bound states, a metastable surface bound state and a dominant inserted state. In both states positively charged PGLa amino acids maintain electrostatic interactions with anionic phosphate groups by rotating the PGLa helix around its axis. PGLa binding causes an influx of anionic DMPG and efflux of zwitterionic DMPC lipids from the peptide proximity. PGLa thins the bilayer and disorders the adjacent fatty acid tails. Deep invasion of water wires into the bilayer hydrophobic core is detected in the inserted peptide state. The analysis of charge density distributions indicated that peptide positive charges are nearly compensated by lipid negative charges and water dipole ordering, whereas ions play no role in peptide binding. Thus, electrostatic interactions are the key energetic factor in binding cationic PGLa to anionic DMPC/DMPG bilayer. Third, we used REST to study PGLa binding to a model anionic DMPC/DMPG bilayer at high P:L ratio, which promotes PGLa aggregation. As a reference we used our previous simulations at the low peptide: lipid ratio. We found that the increase in the peptide: lipid ratio suppresses PGLa helical propensity, tilts the bound peptide toward the bilayer hydrophobic core, and forces it deeper into the bilayer. Surprisingly, at the high peptide: lipid ratio PGLa binding induces weaker bilayer thinning, but deeper water permeation. We explain these effects by cross-correlations between lipid shells surrounding PGLa that leads to a much-diminished efflux of DMPC lipids from the peptide proximity at the high P:L ratio. Consistent with the experimental data the propensity for PGLa self-aggregation was found to be weak resulting in coexistence of monomers and dimers with distinctive properties. PGLa dimers assemble via apolar crisscross interface and become partially expelled from the bilayer residing at the bilayer-water boundary. We rationalize their properties by the dimer tendency to preserve favorable electrostatic interactions between lysine groups and phosphate lipid groups as well as to avoid electrostatic repulsion between lysine in the low dielectric environment of the bilayer core. PGLa aggregation was found to be distinct from that involved in PGLa-magainine heterodimers. Taken together, our studies provide molecular level information on the early events of PGLa binding and aggregation in anionic lipid bilayers
Nudging Vaccination in Latin America: Insights from Three Field Experiments in Behavioral Economics
Get PDFIn this dissertation, I address the impact of various principles of behavioral economics on vaccination rates and attitudes toward vaccines in Latin America with an experimental economics methodology. Each experiment was implemented with government entities in the respective study locations. With the insights generated by these studies, I seek to provide evidence-based recommendations to aid governments in optimizing resource allocation toward effective health promotion. In chapter one, I test the effect of norm nudges on increasing HPV vaccinations for parents of girls and adolescents in Bogota, Colombia, where only a minority of the population is vaccinated against HPV. Norm nudges provide social information describing the prevalence of a behavior and/or its degree of social approval. I use a text message campaign to target parents with daughters between 9 and 17 years old who need the first dose of the HPV vaccine. I compare five norm nudges, a control group, an experimental control group, and a policy control group. Two norm nudges contain social information communicating how other people’s behavior is changing over time, i.e., dynamic norm nudges. The results are based on actual HPV vaccinations from administrative data from the Secretariat of Health in Bogota. The results find that the trending norm, one of the two dynamic designs, increases average vaccination by 1.39 percent compared to the control group vaccination rate of 5.57 percent. It represents a difference in HPV vaccination rate equivalent to 25 percent compared to the control group. This study contributes to the growing literature on the applications of dynamic norm nudges on behavior change. In chapter two, I examine the effectiveness of dynamic norm nudges on increasing second-dose HPV vaccinations for trendsetters. I follow the definition of trendsetters by Bicchieri and Funcke (2018). They define trendsetters as the initiators of norm abandonment. In this context, trendsetters are parents who vaccinated their daughters with the first-dose HPV vaccine between 2017-2020. The results are based on actual HPV vaccinations from administrative data from the Secretariat of Health in Bogota. The paper tests three variations of dynamic norm nudges that include trending norms, qualitative dynamic norms, and quantitative dynamic norms. Contrary to chapter one, the results indicate that dynamic norms do not increase second-dose HPV vaccination rates of trendsetters. However, injunctive norms have a statistically significant marginal increase in second-dose HPV vaccinations of 5.22 percent compared to the control average of 15.2 percent. This difference is equivalent to a 34 percent difference. The study contributes to the literature on the effect of norm nudges on minority behaviors and identifies the elements that make dynamic norm nudges effective in this context. In addition, the study contributes to the literature on the specific conditions under which norm nudges are effective. In chapter three, I test the hypothesis that online interventions grounded in the principles of behavioral economics, that is, nudges, impact COVID-19 vaccine attitudes. I test the hypothesis with a field experiment in cooperation with the government of Guanajuato, Mexico. Contrary to public health communications interventions, the behavioral economics approach assumes that individuals suffer from limited attention and cognitive resources that constrain information processing. This study’s approach uses elements of gamification, heuristics, altruism, and framing to support the visual and message intervention to simplify the cognitive processing of information, thereby making information more salient. The results show that the online behavioral intervention has a positive effect on vaccine attitudes of 0.207 points on a 9-point scale from 1-9, where 1 is completely against, and 9 is completely in favor of the vaccine. Since recent studies show that vaccine attitudes have declined, low-cost interventions like the one studied in this chapter may hold the promise of containing a continued decline
WHAT MAKES INTERNATIONAL STUDENTS RESILIENT: AN EXPLORATION OF INTERNATIONAL STUDENT NARRATIVES ABOUT SOCIAL SUPPORT, BASIC PSYCHOLOGICAL NEEDS, RESILIENCE, COVID-19 AND WELLBEING
Get PDFInternational students face unique challenges impacting their journey while studying in the United States. The purpose of this research was to better understand the support needs of international students, its impacts on their wellbeing, and to understand better how they demonstrate resilience, despite all the challenges they face. Fifty-three participants answered semi-structured questions sharing their experiences as international students. The results show international students felt an overall sense of wellbeing and flourishing when they fulfilled their basic psychological needs. Their resilience was impacted by the different types of social support they received, and findings explored how they navigated these different support systems on campus. Additionally, COVID-19 impacted participants in unique ways; due to the different intersections of their identities, they navigated these stresses differently. Lastly, participants who were able to find the support and resources necessary for success thrived in their adjustment and journey as international students. The participants' experiences confirmed the essential role of universities in the adjustment of international students. Based on these findings, recommendations are made for universities, international offices, and international students