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Overshooting Convection in the Contiguous United States: Severe Hail Occurrence, Storm Top Characteristics, and Stratospheric Hydration
Get PDFDeep convection that overshoots the tropopause have been recognized for its relevance to stratospheric composition and prolific severe weather production for decades. Notably, tropopause-penetrating storms can inject cloud ice above the tropopause and the broader storm anvil, producing ice clouds called above-anvil cirrus plumes (AACPs). When transported into the upper troposphere and lower stratosphere (UTLS), the convectively-influenced air can modify the surrounding environment, resulting in short- and long-term impacts. Supercell storms, argued to be responsible for the majority of U.S. severe hail reports (especially for the largest sizes), also frequently produce AACPs due to the strong updrafts needed for supercell maintenance. However, U.S.\ hail report databases are plagued by serious limitations, including biases in reported sizes, occurrence time, and location, which has led to the development of various radar-based estimates of severe hail occurrence and hail size. Many established relationships between radar-observed storm characteristics and severe hail occurrence have been found using data for few storms and in isolation from other radar metrics. In addition to previous work being spatially and temporally limited, recent improvements to radar-based metrics warrant detailed comparisons between original and updated parameters.
While radar-based analyses of storm and associated severe report characteristics have a rich history, much less work has been done on these aspects of explicitly AACP-producing storms and the AACP itself. Recent studies of AACPs have shown large variability in their satellite-observed features, particularly in infrared (IR) imagery, although many of the causes remain unknown. The typical altitude range in relation to the storm anvil and tropopause height, in situ trace gas observations, and stratospheric hydration variability are all aspects of AACPs that have little-to-no existing research. The recently conducted NASA Earth Ventures Suborbital field project, Dynamics and Chemistry of the Summer Stratosphere (DCOTSS), was specifically designed to collect in situ observations and multi-satellite imagery of convectively-injected material (i.e. AACPs) in the stratosphere to better understand their effects on the chemistry, dynamics, and radiative features that are characteristic of the upper troposphere and lower stratosphere (UTLS). By leveraging the different viewing geometry between two satellites simultaneously observing one region, stereoscopy (stereo) can estimate cloud-top heights for AACPs and other cloud features. Although a few studies have utilized stereo for older generations of satellites, there lacks a focused effort to update stereo methods for next-generation satellites.
Motivated by the vast knowledge gaps in AACP understanding, associated climate impacts, existing challenges for objective severe hail identification, and recent DCOTSS observations of AACPs, the four projects detailed herein aim to better understand deep, severe convective storms on climatological timescales and their potential impacts on the climate by utilizing long data records and/or recent, novel observations. The first study aims to quantify severe hail fall characteristics during a markedly longer time period than previous studies, using both radar observations and reanalysis data, and found that an environmentally-filtered radar-based U.S.\ hail climatology provided the greatest agreement with reports. The second study evaluates the reanalysis-represented environments of radar-identified supercell populations with different maximum reported hail size, and found that the greatest differences exist in the wind speed perpendicular to storm motion. The third study compares warm and cold AACP-producing storms (based on IR signatures) using ground-based radar observations and reanalysis data to better understand the different AACP IR signatures. This study found that cold AACPs tend to occur in tropical environments (higher, cold-point tropopauses), while warm AACPs tend to occur in mid-latitude environments (lower tropopauses and an isothermal layer in the lower stratosphere). Storm-relative environmental characteristics indicate that cold AACPs are predominantly tropospheric phenomena, while warm AACPs reside in the lower stratosphere. The fourth, and final study applies a recently developed stereoscopic cloud-top height retrieval algorithm for modern GOES visible imagery to DCOTSS research flight 13 (RF13) on 31 May 2022 for comparison with in situ water vapor observations. Preliminary stereo results show moderate agreement with various observational datasets but concerning nonphysical features.
Overall, these studies provide further evidence that radar-based hail identification and size estimation can benefit from incorporating environmental information, particularly in a storm-relative framework. These studies additionally highlight the importance of understanding trace gas composition and satellite observations of AACPs to accurately characterize their impacts on the UTLS
Novel annexin A5 - nanoparticles conjugates for targeted cancer therapy
Get PDFCancer is considered the single most critical barrier to improving life expectancy in every country. More specifically, the high prevalence of breast cancer is a global health concern, but there are no safe or effective treatments for it at its advanced stages. Those facts urge the development of novel treatment strategies.
Annexin A5 (ANXA5) is a natural human protein that binds with high specificity to phosphatidylserine, a phospholipid tightly maintained in the inner leaflet of the cell membrane on most healthy cells but externalized in tumor cells, tumor vasculature, and metastatic cells. We have linked annexin A5 to single-walled carbon nanotubes (SWCNT) and gold nanoparticles (AuNP) in this work.
First, we have developed a targeted photosensitizer for photothermal therapy (PTT) of solid tumors through the functionalization of SWCNT to ANXA5: the SWCNT-ANXA5 conjugate. The ablation of tumors through the SWCNT-ANXA5-mediated PTT synergizes with checkpoint inhibition creating a systemic anti-cancer immune response. This treatment strategy was tested in two murine breast cancer tumor models, EMT6 and 4T1. Although EMT6 tumors are aggressive and metastatic, 4T1 tumors are considered even more threatening and less immunogenic than EMT6. For both tumors, enhanced therapeutic effects were achieved. While EMT6 tumors were treated with lower temperatures in the PTT, 4T1 required higher temperatures and the addition of an immune adjuvant to induce curative effects. For both studies, evidence of immune system activation strengthens the hypothesis of an abscopal effect. SWCNT-ANXA5 was also studied as a responsive material for radiofrequency ablation (RFA), showing an impressive heating rate and potential for carbon nanotube-mediated RFA of tumors.
Lastly, a multi-modal conjugate for the detection and therapy of cancer was developed linking ANXA5 to a chemotherapeutic drug, mertansine (DM1), and gold nanoparticles (AuNP) for drug delivery and contrasting agent in microCT scans in the diagnosis of breast cancer. Those linkages created the conjugate AuNP-ANXA5-DM1. This novel agent was able to induce cytotoxic effects and has the potential to increase the effectiveness of chemotherapeutic delivery to solid tumors
Don vampiro. Ecos donjuanescos del vampiro seductor en el relato Español de los siglos XX y XXI
Get PDFDon Vampiro: Ecos donjuanescos del vampiro seductor en el relato español de los siglos XX y XXI, focuses on the archetype of the seductive vampire as it evolved from an agent of traditional patriarchal values to a beacon for feminism and the LGBTQ community. I detail the transnational influence of the Iberian Don on subsequent representations of the archetype, tracing its evolution from purely Donjuanesque to vampiric manifestations. I explore the transatlantic impact of this archetype in literature, film, and television and how it has evolved from causing fear to being the ideal prince charming. I begin with early representations, but I particularly center my analysis on Peninsular Hispanic iterations in the 20th and 21st centuries
Creation of Hyper-Doped Crystalline Titania Thin Films by the Kinetic Doping Method for Solar Cell Anode Material
Get PDFThis work outlines the general process of kinetic doping and how its benefits have been expanded from silica-based applications to use in titania thin films. While this has potential for many applications, the utilization focused on in this work is as a novel approach to the fabrication of anode material in dye-sensitized solar cells (DSSCs).
Chapter 1 discusses the general pathways of the sol-gel process and various methods of guest molecule loading. This includes the kinetic doping method which will be utilized in this work. Chapter 2 will go into further detail on the research field of dye-sensitized solar cells (DSSCs) and how this work may be a benefit to the field. Chapter 3 is a record of the various materials, instrumentation, and methods utilized to accomplish the experiments in this work.
The main work of creating the hyper-doped TiO2 thin films for utilization as a DSSC anode material is discussed in chapters 4-6. The general steps to accomplish the prototype DSSC based on our intended anode material are:
(i) to establish kinetic doping in TiO2 thin films
(ii) to broaden the wavelength range of light absorbed by loading multiple dyes at once
(iii) to crystallize the amorphous dye-doped TiO2 thin films while minimizing the damage to dye molecules caused by thermal degradation
(iv) to create and evaluated the performance of prototype DSSCs using the material established in the first three steps.
Chapter 4 will discuss the challenges and results of steps (i) and (ii), establishing the protocols for creating hyper-doped amorphous TiO2 thin films and one-pot loading of multiple dyes. In theory, since the hydrolysis and condensation chemistry taking place in silica sol-gels and titania sol-gels is inherently very similar, kinetic doping in titania sol-gels is expected to follow the same general pathway as silica sol-gels. However, since the titanium dioxide precursor is more reactive than the silicon dioxide precursor, kinetic doping in titania sol-gels will clearly not be identical to kinetic doping in silica sol-gels. Concentrations as high as 0.7 - 1.9 M in thin films from 120-250 nm thick are achieved for various dyes from a 1 mM loading solution. Up to four dyes are loaded in a single-step loading process, resulting in an absorption range from 300 – 700 nm.
Step (iii), crystallization of the amorphous dye-doped TiO2 thin films is also important. The amorphous thin films may work in a prototype but would almost certainly be more effective in a crystalline form. As the traditional crystallization process of heating at high temperatures is expected to degrade the loaded organic dye molecules, a lower temperature crystallization process will likely be needed. Chapter 5 describes this low-temperature method of TiO2 thin film crystallization, and the challenges associated with establishing the protocol. The final protocol results in an 85% dye retention rate, which allows the advantage of kinetic doping to be manifested in the final crystallized thin film. Multilayer thin films are created and undergo crystal transformation in a single step, indicating a high degree of tunability for the final thickness of a DSSC anode made from this material.
The final step, (iv), the creation of a prototype, is discussed in Chapter 6. Creating a prototype is a fundamental part of establishing whether these hyper-doped TiO2 thin films have the potential to produce high efficiency anode materials for DSSC. The prototype power conversion efficiency achieved ranges in efficiency from 0.001-0.008%, which is on par with the literature efficiency of DSSCs utilizing analogous dyes and redox electrolyte solution. It is even within an order of magnitude of DSSCs that use the same analogous electrolyte and high-efficiency dyes. Avenues for further improvement to the prototype DSSCs are also discussed
Piloting an Assessment of Foundational Workplace Competencies for Students with Disabilities and Competitive Employment Aspirations
Get PDFIt is critical students with disabilities be adequately prepared with the foundational competencies necessary for entry-level employment. However, the field needs a research-based, structurally sound assessment to assist teachers in assessing such competencies and then writing appropriate transition goals. The purpose of this pilot study is to determine whether modifications can be made to the Employer Identified Trait Assessment for use in school settings without altering its underlying structure. Data were collected from 402 transition-aged students, professionals, and family members. Three versions of the EITA were modified for use in this pilot study. Results show modifications did not influence the underlying assessment structure. Implications for practice are discussed.This is the accepted manuscript version of the following article: Maeghan Hennessey, “Piloting an Assessment of Foundational Workplace Competencies for Students with Disabilities and Competitive Employment Aspirations,” Career Development and Transition for Exceptional Individuals (Forthcoming). The supplemental file presents R Code for CFA analyses conducted for that article.A grant from the Institute of Education Sciences, National Center for Special Education Research, grant award number R324A100246, in part, supported this research project.Ye
Was that Rudeness or Racism? Exploring the Moderating Effect of Attribution to Racism on Experiences of Incivility
Get PDFIncivility is a typical way that subtle discrimination manifests in academic contexts and may be a key contributor to racial and ethnic disparities in student wellbeing and achievement. Research testing ethnic identity as a protective factor for victims of subtle discrimination has yielded mixed results, with one study finding ethnic identity to be associated with attributing mistreatment to prejudice. The present study uses structural equation modeling to investigate ethnic identity as a protective factor students experiencing incivility by exploring the moderating effect of attributions to racism on the relationship between incivility and strain. Understanding the role that attributions may have in buffering the effects of subtle discrimination would give insight into the processes underlying ethnic identity as a protective factor, which may inform the development of positive tools and resources for minoritized students
An analysis into the exploitation of the post-attendee URL feature in Zoom webinar regarding malware transmission
Get PDFIn response to the COVID-19 pandemic, large businesses and organizations relied on video conferencing applications such as Zoom to maintain public health guidelines due in part to their robust set of features to facilitate productive group events while maintaining social distancing recommendations. While Zoom has many features that can be found in similar video conferencing applications, Zoom also contains a plethora of unique and cutting-edge features to entice modern users. However, when new features are introduced, an inherent risk of vulnerability exploitation has the potential to overshadow the benefits of the feature. One such vulnerable feature within Zoom webinar that is often overlooked is the post-attendee URL, a feature that allows Zoom webinar hosts to set a URL that participants will be redirected to after joining. This study aims to showcase the vulnerabilities of this feature by utilizing URLs of malicious websites and direct download links of files to transmit malware to Zoom webinar participants of the desktop application version of Zoom webinar. This study will also provide an analysis of the residual digital artifacts that are left behind when this feature is utilized to provide digital forensic examiners with the ability to create a comprehensive timeline of events for cases involving this type of attack
A novel polysaccharide-based surface engineering strategy for nanomedicines
Get PDFThis dissertation presents the development and evaluation of a novel polysaccharide-based surface engineering strategy for nanomedicines.
Chapter one summaries the current status of nanoparticle toxicology. Nanoparticles from natural and anthropogenic sources are abundant in the environment, thus human exposure to nanoparticles is inevitable. Due to this constant exposure, it is critically important to understand the potential acute and chronic adverse effects that nanoparticles may cause to humans. In this chapter, we explore and highlight the current state of nanotoxicology research with a focus on mechanistic understanding of nanoparticle toxicity at organ, tissue, cell, and biomolecular levels. We discuss nanotoxicity mechanisms, including generation of reactive oxygen species, nanoparticle disintegration, modulation of cell signaling pathways, protein corona formation, and poly(ethylene glycol)-mediated immunogenicity. We conclude with a perspective on potential approaches to advance current understanding of nanoparticle toxicity. Such improved understanding may lead to mitigation strategies that could enable safe application of nanoparticles in humans. Advances in nanotoxicity research will ultimately inform efforts to establish standardized regulatory frameworks with the goal of fully exploiting the potential of nanotechnology while minimizing harm to humans. (Chapter 1)
Chapter two introduces the use of polysaccharide heparosan (HEP) surface modification on nanoparticles as an alternative to poly(ethylene glycol) (PEG) and showed the investigation of the biological interaction of HEP coated nanoparticles with cells. Nanoparticle modification with PEG is a widely used surface engineering strategy in nanomedicine. However, since the artificial PEG polymer may adversely impact nanomedicine safety and efficacy, alternative surface modifications are needed. Here, we explored the ‘self’ polysaccharide HEP to prepare colloidally stable HEP-coated nanoparticles, including gold and silver nanoparticles and liposomes. We found that the HEP-coating reduced the nanoparticle protein corona formation as efficiently as PEG coatings upon serum incubation. Liquid chromatography-mass spectrometry revealed the protein corona profiles. Heparosan-coated nanoparticles exhibited up to 230-fold higher uptake in certain innate immune cells, but not in other tested cell types, than PEGylated nanoparticles. No noticeable cytotoxicity was observed. Serum proteins did not mediate the high cell uptake of HEP-coated nanoparticles. Our work suggests that HEP polymers may be an effective surface modification technology for nanomedicines to safely and efficiently target certain innate immune cells. (Chapter 2)
Chapter three describes the HEP-AuNPs uptake behavior and pathways in immune cells and established controlling strategies for nanoparticle cellular uptake. Our findings indicate that HEP-coated nanoparticles were endocytosed in a time-dependent manner by innate immune cells via both clathrin-mediated and macropinocytosis/phagocytosis pathways. Upon endocytosis, HEP-coated nanoparticles were found in intracellular vesicles as well as in the cytoplasm, demonstrating the potential for nanoparticle escape from these intracellular vesicles. Competition with other glycosaminoglycan types inhibited the endocytosis of HEP-coated nanoparticles only partially. We further found that nanoparticle uptake into innate immune cells can be controlled by more than 3 orders of magnitude via systematically varying the HEP surface density. Our results suggest there exists substantial potential for HEP-coated nanoparticles to target innate immune cells for efficient intracellular delivery, including into the cytoplasm. This HEP nanoparticle surface engineering technology may be broadly used to develop efficient nanoscale devices for drug and gene delivery as well as gene editing and immuno-engineering applications. (Chapter 3
Minutes of a Regular Meeting, The University of Oklahoma Board of Regents, May 12-13, 2022
No full textDoes financial statement presentation in 10-K filings matter?
No full textI explore two novel characteristics of financial reporting, the order in which the financial statements are presented in the annual 10-K filing (financial statement order or FSO) and the number of times financial statements are mentioned in the 10-K (financial statement mentions or FSM). In this study, I explore the determinants of FSO and FSM signals for the income statement. Additionally, I provide evidence that FSO and FSM income statement signals are related to characteristics of earnings. In particular, I show that FSO and FSM are related to the persistence of earnings and the weights on earnings and book value in valuation. I also show that earnings response for future earnings is related to FSM. Overall, I show that FSO and FSM are related to earnings and valuation properties and may be one method managers can communicate relevant information about earnings