UMD Theses and Dissertations

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PERFORMANCE OF THE VIOLIN CONCERTO AND SONATAS OF JOHANNES BRAHMS WITH AN ANALYSIS OF JOSEPH JOACHIM'S INFLUENCE ON HIS VIOLIN CONCERTO
(1997) Hsieh, I-Chun; Heifetz, Daniel; Music; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
This dissertation consists of a performance project and extensive studies of selected works by Johannes Brahms, including the Violin Concerto, Sonatensatz, and three Violin Sonatas. The performance project was presented in two recitals at the University of Maryland, College Park, on November 14, 1997, and November 16, 1997. The first recital featured Brahms' s Sonatensatz in C Minor, Violin Sonata No. I, Op. 78 in G Major, and Violin Sonata No. 3, Op. 108, in D Minor. The second recital included Brahms' s Violin Sonata No.2, Op. 100, in A Major and Violin Concerto Op. 77, in D Major. Section One gives an overview of this dissertation project. Section Two introduces the violin virtuoso Joseph Joachim, his relationship with Johannes Brahms, and Brahms' s life and major violin works. This section also analyzes Joachim' s performance practice and his teaching style. The end of this section focuses on the influence of Joseph Joachim on Brahms' s Violin Concerto and indicates the differences between Brahms' s original manuscript and the version suggested by Joachim. Section Three is composed of the programs of the two recitals. Section Four consists of program notes for the two recitals. The first recital was performed by I-Chun Hsieh, violin and Roy Hakes, piano. The second recital was performed by I-Chun Hsieh, violin and Chia-Hsuan Lee, piano.
Baroque Plague Imagery and Tridentine Church Reforms
(1990) Boeckl, Christine M.; Pressly, William; Art History & Archaeology; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
This dissertation aims to achieve two goals: one, to assemble as many facts as possible about the plague, regardless of period, and to relate this material to images; and two, to present a well-defined group of religious baroque plague paintings in the context of social, political and religious history. This inquiry is primarily concerned with scenes that portray saints actively involved in charitable pursuits, dispensing the sacraments to victims of the most dreaded disease, the bubonic plague. Chapter I contains a bibliographical essay, divided into three parts: medicine, theology, and art history. The next chapter considers the sources and the formation of baroque plague iconography. The remaining two chapters discuss "documentary" plague scenes and how they relate to historic events. They are presented in two sections: Italy and transalpine countries. This interdisciplinary research resulted in a number of observations. First, these narrative plague scenes were produced in Italy and in Catholic countries bordering Protestant regions: Switzerland, France, Flanders, and in the Habsburg Empire (excluding Spain). Second, the painters were mostly Italian or Italian-trained. Third, the artists observed not only the requirements specified by the Church in the 1563 Tridentine Decree on the Arts but also reflected in their work the catechetic teachings of the Council. Fourth, these religious scenes were not votive paintings but doctrinal images that served either didactic or polemic functions. Fifth, the scenes were not intended as memento mori; rather, the iconology conveyed positive images which emphasized that the faithful needed the Roman Catholic clergy to gain life-everlasting. Sixth, these plague paintings were important documents not as recordings of the conditions experienced during an epidemic but as historic testimony of liturgical practices. Last, these selected scenes mirrored the baroque Church's views on the ultimate questions about life and death.
The Effects of Instruction in Sentence Combining and Revision on Ninth and Tenth Graders' Explanatory Writing
(1989) Horstman, Franklin; Slater, Wayne H.; Teaching, Learning, Policy & Leadership; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
In this study, I examined the effects of instruction in sentence combining on three measures of student writing : 1.) syntactic fluency; 2.) overall writing quality; and 3.) sentence -combining ability. Sentence combining is a method of writing instruction in which students rewrite a series of sentences into one syntactically more complex sentence. Two teachers instructed experimental group one (37 students) in sentence combining applied to revision. The same two teachers also instructed experimental group two (37 students) in sentence combining alone. A third teacher instructed the control students (38 students) in the standard ninth-grade English curriculum. To examine syntactic fluency, I analyzed students' writing for words per T-unit, clauses per T-unit, and words per clause. To examine overall writing quality, two trained raters assessed students' writing using forced choice holistic scoring. I also assessed students' sentence-combining ability. On syntactic fluency, the control group demonstrated statistically significant gains for mean number of words per clause. On overall writing quality, the control group also demonstrated statistically significant gains. On sentence-combining ability, both experimental group one and experimental group two demonstrated statistically significant gains. While the results do not support the first two research questions, on sentence-combining ability, the results suggest that ninth-grade writers can be taught sentence combining in a four-week, intensive instructional unit. Additionally, results suggest links between rhetorical and psychological theories and writing. However, the limitations of the results also suggest further sentence-combining research.
The Folklore and Life of My Native Country in Pictorial Terms
(1967) Al-Harithi, Naziha Rashid; Maril, Herman; Art; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
The content of this thesis exhibition is involved in exploration of the folklore and life of the people of my native country in terms of a more contemporary painting language. Color symbols and patterns play a great role in these concepts.
Development and Preliminary Validation of the Religious Identity Development Scale
(2002) Veerasamy, Suthkaran; Hoffman, Mary Ann; Counseling and Personnel Services; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
The purpose of this study was to examine the psychometric properties of a new measure of religious identity development, the Religious Identity Development Scale (RIDS). The study also explored the relationship among religious identity development, anxiety and dogmatism to determine convergent and discriminant validity for the RIDS. The concurrent validity for the RIDS was determined by exploring the relationship between intrinsic and extrinsic religious orientations. The religious identity measure that was validated in this study was based on a proposed model of religious identity development, the Experiential/Rational Model of Religious Identity Development. The participants for the study were 211 students and adults from the Midwest and East coast. They completed the Religious Identity Development Scale (RIDS; V. Suthakaran, 2002), the Rokeach Dogmatism Scale (Rokeach, 1960), the State subscale of the State-Trait Anxiety Scale (Spielberger, 1983), Age Universal Intrinsic-Extrinsic Scale (Gorsuch & Venable, 1983), and the Marlowe-Crowne Social Desirability Scale (Crowne & Marlowe, 1960). Exploratory factor analysis supported a six-factor model better than a seven-factor model. Discriminant validity was demonstrated by the negative correlations of the Acceptance status with anxiety and dogmatism, and the negative correlation of the Cognitive-Rationalization status with anxiety. Convergent validity was demonstrated by the positive correlations of the Concrete, Relational and Cognitive - Rationalization statuses with dogmatism, and the positive correlation of the Confusion status with anxiety. Some evidence, albeit modest, was found for concurrent validity, in that the Relational status was positively correlated with extrinsic religious orientation, and the Exploration status was positively correlated with intrinsic religious orientation. The negative correlation of the Cognitive-Rationalization status and the Confusion status with intrinsic religious orientation also provided tentative evidence for concurrent validity. Additional preliminary support for the concurrent validity of the RIDS was provided by examining the relationship of the six statuses with a two-dimensional definition of intrinsic and extrinsic religious orientation. Finally, results appeared to indicate that the internal consistencies and test-retest reliabilities were adequate, except for the Relational status. The methodological limitations of the study and implications for counseling psychology were discussed. Suggestions for future research for refinement of methodology were offered.
The Washington Bronze Dionysos
(1994) Bennet, Susanne Klejman; Venit, Marjorie Susan; Art History & Archaeology; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
A life-size bronze of a nude youth was discovered in a river in Asia Minor in the early 1960's. The bronze no longer had the iconographic attributes that it had once held in its hands, but the head presented features which made it possible to identity the figure as representing the god Dionysos. The sculptor drew upon earlier prototypes, specifically a figure called the Westmacott athlete, which has been tentatively attributed to the Greek sculptor Polykleitos. The head of the statue reflects a different, possibly female, prototype. An investigation of a group of Roman life-size and three quarter life-size bronzes reveals that the iconographic details which identity the Washington Bronze also place it outside the category of lamp hearers to which the majority of the other statues belong. The physiques of the majority of the lamp bearers and of the Washington Bronze, however, reflect the same Polykleitan prototypes. The identification of the Washington Bronze as a devotional rather than functional statue is made through a study of the literary, religious, and archaeological evidence. The evolution in the iconography of the god is traced through his portrayals on Greek vases and in Graeco-Roman bronze and marble statuary. The Bronze was created in the Eastern Roman Empire. Through a comparative analysis of other bronzes it can be dated within the period between the beginning of the Augustan era and the third quarter of the first century A. D. A setting in the home of a devotee of the Dionysian Mysteries is adduced.
The Effects of Variation in the Amount of Play Materials on the Play Behavior of the Preschool Child
(1978) Rechsteiner, Ann E.; Leeper, Sarah L.; Human Development & Quantitative Methodology; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
Major questions have arisen concerning the function of play in the development of the young child. Changing attitudes towards the significance of play reflect changing social patterns. The present study was concerned with the effect that a removal of a specified amount of play material had on the play behavior of young children. Ten intact groups of children from the Washington, D.C. Metropolitan Area ranging in age from three to five years old were studied by this researcher. A time sampling technique using a modified version of DUSOPAC was used to measure the play behavior of the groups. The data collected by the observers were compiled and analysed using a one way ANOVA for a repeated measure design for each of the eleven variables (Disruptive, Unoccupied, Solitary, Onlooker, Parallel, Associative, Cooperative, Not Play, Child-Child, Child-Adult, Child-Self.) The findings indicated that a significant relationship (at the .05 significance level) existed between the amount of social play observed and the amount of play equipment that was available to the young child. Less social play was observed when the material was removed on the first treatment day than when the material was present. No significant relationships were observed between the amount of equipment available and the amount of non-social play, the amount of child-child interaction, the amount of child-self interaction, or the amount of child-adult interaction that occurred. Investigation of the mean score values revealed trends for both interaction patterns and play behavior. Females were found to display more child-self interaction behavior and males more child-child interaction behavior. Also, for all days of observation, regardless of treatment, the most frequently occurring interaction behavior was child-child followed by child-self. The least frequently occurring interaction behavior was child-adult. For play behavior for all days of observation, regardless of treatment, males displayed more disruptive, unoccupied, associative, cooperative, parallel and social play behavior than did females. Females were found to display more solitary, onlooker, not-play and non-social play behavior than were males. These findings were not in agreement with Langlois, Gottfried and Seay (1973), and Sitzky, Haywood and Isett (1970 ). The results of this study seem to indicate that there is a need for more research to 1) update earlier studies; 2) study the role of play in the development of social interactions; 3) investigate saturation levels of equipment as they relate to a child's play; 4) to explore in more detail environmental influences on play behavior.
Land Use in Charles County
(1962) Langen, John S.; Van Royen, W.; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
The land use of Charles County does not basically differ from that in the past. Land in forest and land in farms are the two categories of land utilization. The great demand for tobacco on the overseas markets in the early days of the county's history, led to the introduction of this crop. Because of the favorable climate and soils, tobacco became soon the mainstay of the county's economy, a situation which still exists today. The purpose of the thesis was to determine which geographical factors and others accounted for the use of the land. In addition to field work, use was made of detailed statistical data. It was found, that the county could be divided into three sections. In the western section, land in forest was the dominating land use form. In the central section, land in forest and land in farms were about equal in areal extent, whereas in the eastern section, land in farms dominated. The reason was that soils in the western part became exhausted, and a shift to the eastern section took place. Landforms contributed much to the distribution of land in crops, especially for tobacco. Recently, a change in the use of the land is taking place. The encroachment of the Washington Metropolitan area, and the building of a major highway, connecting the North with the South, have induced farmers to sell their lands, which are converted into residential areas.
Juvenile Delinquency and the Negro in Charles County, Maryland
(1966) Seaman, Thomas W.; Lejins, Peter P.; Sociology; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
Are there differences between Negro and white juvenile delinquents? This was the question that constituted the basis for this exploratory study. The objectives of the project were to determine if Negro juveniles were proportionately overrepresented among juvenile delinquents and if there were differences in types of offenses committed by Negro and white delinquents. The differences found were analyzed in the light of socio-economic class differences between Negro and white delinquents. Previous research has tended to indicate that racial differences disappeared when socioeconomic class was held constant. The area selected for the project was Charles County, Maryland, because of the writer's access to court records and knowledge of the area. Delinquency rates were developed to determine if Negroes were proportionately overrepresented among delinquents and/or if lower class juveniles were overrepresented among delinquents. Delinquent offenses were divided into four types: offenses involving theft or attempted theft of property, offenses involving violence, offenses involving the destruction of property, and offenses injurious to the child himself. Delinquency rates were developed for Negro and white delinquents in each socio-economic class for each type of offense. A simple ecological investigation was conducted to determine if there were any significant patterns in the spatial distribution of the delinquents. The findings show that Negro juveniles were not significantly overrepresented among delinquents even though Negro delinquents were overrepresented among lower-lower class delinquents. White delinquents were found to be overrepresented among delinquents from the lower-middle and upper-lower classes. The analyses of types of offenses revealed that types of offenses could be identified with certain levels of the socio-economic structure regardless of race, but that differences existed between Negro and white delinquents within socio-economic classes. The ecological investigation indicated that there was no significant ecological pattern among county delinquents.
Exploring and Propagating Oboe Music From Composers of South Asian, African, and Middle Eastern Heritage
(2023) Helgerman, Michael Andrew; Hill, Mark
Though the oboe has enjoyed both a rich history and contemporary renaissance as a solo voice, the instrument's repertoire bears some rigidity and limitations in representing composers from diverse backgrounds. A repertoire survey from a 2001 edition of the Double Reed Journal denotes a clear tendency towards homogeneity of composer background in the instrument's canon. After contacting oboe professors employed at universities across the United States, compiler Susan Lundberg published lists of concerti, sonatas, chamber pieces, and other works that "oboists should know"; every piece listed in the top ten results of each genre was written by a male composer of European or American descent. This dissertation project will serve as a small step among the many needed for the oboe's solo repertoire to evolve into a canon that equitably represents composers from all backgrounds. In particular, composers with South Asian, African, and Middle Eastern roots will enjoy the spotlight in this dissertation, as these cultures boast rich musical foundations whose synthesis with the modern oboe has yet to receive significant research.
The Cowbell in Music and Culture
(2023) McGovern, John; Votta, Michael; Music; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Cowbells are used as percussion instruments in a variety of musical settings today. Such uses represent a number of distinct musical practices. In this dissertation I attempt to chronicle cowbells in music from the first such use (the mid-19th century) to the present day, with a focus on historically linking and differentiating cowbell practices in orchestral music, in early musical theater and popular music, and in Cuban and Cuban-derived music. I argue furthermore that perceptions of the cowbell and its connotations, in the cultures that produce these musical practices, affect the way that the instrument is used and perceived. The word “cowbell” makes no differentiation between cowbells used historically for farming and the modern instruments descended from them. This, coupled with historical associations between cowbells and the carnivalesque exemplified by charivari practices, has led to perceptions of the cowbell, throughout its musical history, as an object of othering, humor, and/or derision.
Essays on the Epistemology of Polycentriicty and Democracy
(2023) Manor, Aylon; Kogelmann, Brian; Philosophy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
This dissertation investigates the epistemic properties of two institutional types, polycentricity and democracy, and explores how these ideals can be translated into concrete plans for institutional design. The dissertation consists of four papers, with the first two papers investigating the epistemic case for polycentricity and its relation to moral arguments, while the remaining two papers investigate the epistemic properties of democracy. The first paper argues that the epistemic case and moral case for polycentricity point toward different polycentric arrangements, while the second paper highlights two dimensions through which polycentric arrangements can generate epistemic value. The third paper proposes a two-stage political process using a Wikipedia-inspired platform to filter for quality information and allow all citizens to participate, while the fourth paper argues for the normative significance of "epistemic equality" in voting methods and explores its implications for alternative methods.
Evaluating the Potential Benefits and Sustainability of a Novel Living and Dead Cover Crop Mixture in Mid-Atlantic Crop Production
(2023) Johnson, Veronica; Hooks, Cerruti RR; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Modern vegetable production systems are often characterized by monoculture fields andthe intensive use of tillage and/or synthetic agrochemicals for managing weeds and insect pests. A growing public interest in more sustainable and eco-friendly production practices has resulted in increased demand that crops be produced with lower inputs. Incorporating flowering living mulches and cover crop residues within crop fields can create an environment more hospitable to beneficial organisms and less conducive to pest outbreaks. My dissertation research aims to advance our knowledge in this area by evaluating the impacts of a novel cover cropping tactic which involves combining a perennial flowering living mulch with cover crop residue on insects and/or weeds. Further, it is often suggested that weed management requires a holistic approach; and that cover cropping will not be successful as a sole weed management tactic. As such, another research aim is to investigate whether combining a cover cropping tactic with herbicide sprays would result in better weed suppression and increased yield in sweet corn compared to using cover crops alone. An economic assessment was also performed to further evaluate the practicality of sweet corn producers adopting the management practices being investigated. Cost of seeds, labor and other expenses can be a primary limitation to cover crop usage. To this point, I also evaluated the feasibility of using a single cover crop planting to suppress weeds over multiple cropping systems and field seasons. If a single cover crop planting can be used over multiple seasons, this could reduce the cost of cover crop use. Agricultural intensification and conversion of natural landscapes to crop production fields have contributed to declines in insect biodiversity including natural enemies and pollinators. Advancing our understanding of how increasing vegetational diversity within crop fields influences weed pressure and populations of herbivores and beneficial arthropods, as well as production costs, can facilitate the adoption of practices in annual cropping systems that favor beneficial organisms and conserves insect biodiversity.
UNVEILING THE SELF-ASSEMBLY OF POLYMER-GRAFTED NANOPARTICLES IN SELECTIVE SOLVENTS
(2023) Lamar, Chelsey; Nie, Zhihong; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The self-assembly of inorganic nanoparticles (NPs) has garnered considerable attention due to the potential for fabricating functional structures with unique collective properties. In recent years, polymers have emerged as valuable candidates in assisting the organization of NPs into complex architectures with multiple capabilities. Researchers have shown that polymer-grafted nanoparticles (PGNPs) facilitate the use of advanced nanostructures with tailored properties in biomedical applications. Although, continued exploration of the rational design and tailoring of PGNP assemblies is needed to expand our understanding before we can fully realize the potential of these structures in desired applications. My dissertation aims to investigate the fundamental aspects and elucidate the underlying mechanisms in the self-assembly of PGNPs for modern biomedical applications. A facile and versatile solution-based strategy was utilized to explore the individual self-assembly of PGNPs with anisotropic NPs and the co-assembly of binary PGNPs with distinct sizes. We focused on designing, characterizing, and exploring the optical properties of hierarchical assembly structures produced from inorganic NPs tethered with amphiphilic block copolymers (BCPs). Individual PNGPs with anisotropic NPs and binary mixtures of small and large PGNPs produce vesicle structures with well-defined packing arrangements. My work shows how key parameters, including polymer chain length, nanoparticle size, and concentration, influence the self-assembly behavior and the formation of vesicles in each system. Through a combination of experimental observations and theoretical considerations, I highlight the significance of polymer shell shape in dictating the self-assembly behavior of individual anisotropic PGNPs. Moreover, I demonstrate that elevated temperatures impacted the stability and optical responses of the vesicle structures. In co-assembly studies, my work describes the macroscopic segregation of PGNPs with different sizes in the vesicular membrane, which is attributed to the conformation entropy gain of the grafted copolymer ligands. This research will provide valuable insights into the self-assembly behavior and fundamental design of PGNP structures relevant to biomedical applications.
MULTI-GEV LASER WAKEFIELD ACCELERATION IN OPTICALLY GENERATED PLASMA WAVEGUIDES
(2023) Shrock, Jaron E; Milchberg, Howard M; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Plasma based electron accelerators offer a promising path to overcoming the significant technological and economic challenges facing the evolution to higher energies by radiofrequency (RF) accelerator technology. In particular, laser-driven wakefield acceleration (LWFA) in plasmas can produce accelerating gradients 1000 times larger than linear RF accelerators, enabling the production of GeV-scale electron bunches in just a few centimeters of acceleration. Efficient LWFA of electrons to this energy scale requires the use of optical guiding to maintain drive laser intensity over much longer distances than the characteristic diffraction length of the pulse. In this dissertation, I will present the first successful implementations of optically generated plasma waveguides in multi-GeV laser wakefield acceleration. I will focus on three primary topics: (1) experimental considerations for generating and diagnosing meter-scale plasma waveguides and the wakefield acceleration process, (2) the experimental demonstration of electron bunches accelerated up to 5 GeV in an all-optical LWFA, and (3) development of a model of drive pulse evolution and electron injection in agreement with a broad range of our experimental results, including the demonstration of localized electron injection through modification of the waveguide properties.
IDENTIFICATION OF TRACE KRYPTON IN THE LUX-ZEPLIN DARK MATTER SEARCH
(2023) Silk, John James; Hall, Carter; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Searches for Weakly Interacting Massive Particles (WIMPs) carried out by liquid xenon time projection chambers (TPCs) require a careful accounting of all background sources. Because WIMPs are a leading dark matter candidate, their possible existence is of great interest to particle physicists, astrophysicists, and cosmologists. The LUX-ZEPLIN (LZ) detector has completed an initial science run finding no evidence for WIMP scattering events. The data excludes scattering cross sections above 6.5x10$^{-48}$ cm$^{2}$ for a WIMP mass of 30 GeV/c$^{2}$. Background contributions from the beta decay of dispersed \isotope[85]{Kr} were reduced prior to the initial science run using charcoal chromatography to remove trace krypton. Over 10 tonnes of xenon were processed, and a custom mass spectrometry system measured a final mass averaged krypton concentration of 123 $\pm$ 22 parts-per-quadrillion (ppq) $\frac{gram}{gram}$ $\frac{ \isotope[nat]{Kr} }{\isotope[nat]{Xe}}$. A delayed coincidence $\beta$ - $\gamma$ search was also conducted to identify rare decays from \isotope[85]{Kr} in the LZ WIMP search data. The 11.0 $\pm$ 4.0 identified events are equivalent to a concentration of 183 $\pm$ 67 ppq. The total background contribution from \isotope[85]{Kr} to the WIMP search region of interest is 30 $ \pm $ 11 electron recoil events.
Spatiotemporal Optical Vortices
(2023) Hancock, Scott; Milchberg, Howard; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Light beams carrying orbital angular momentum (OAM) have become a mainstay of optical science and technology. In these beams, well-known examples of which are the Laguerre-Gaussian (LG_pm ) and Bessel-Gaussian (BG_m ) beams, the OAM vector points parallel or anti-parallel to propagation, and is associated with a phase winding 2πm in the plane transverse to the propagation direction, where integer m is the winding order or the “topological charge”. Such beams can be monochromatic.Recently, our group discovered a new type of OAM structure that naturally emerges from nonlinear self-focusing, which we dubbed the spatio-temporal optical vortex (STOV). Here, the phase winding exists in a spatiotemporal plane, with the OAM pointing transverse to propagation. In this dissertation, we extend the generation of STOV-carrying pulses to the linear regime, demonstrating their generation using a 4f pulse shaper and measuring their free-space propagation using a new ultrafast single-shot space- and time-resolving diagnostic, TG-SSSI (transient-grating single-shot supercontinuum spectral interferometry). We then demonstrate that transverse OAM is a property of photons by experimentally confirming the conservation of transverse OAM in second harmonic generation. Because the field of STOVs is so new, a first principles theory for their transverse OAM was lacking. We developed such a theory for transverse OAM that predicts half integer values of OAM and the existence of a STOV polariton in dispersive media. The surprise of half-integer OAM values launched a debate in the OAM community, which has been resolved in favor of our theory by our most recent experiments. These explore how phase and amplitude perturbations can impart spatiotemporal torques to light. We find that transverse OAM can be imparted to light pulses only for (1) sufficiently fast transient phase perturbations or (2) energy removal from a pulse already possessing transverse OAM.
Sex and the Evolution of a Double Hermaphrodite
(2023) Ficklin, John Alexander; Haag, Eric S; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The Kryptolebias marmoratus species complex contains the only known self-fertile hermaphroditic vertebrates. There are three species in this clade and all three live in the mangrove forests across the tropical Americas. All three have individuals with both testis and ovarian tissue in their gonads with two using self-fertility as their main mode of reproduction, and all three have apparent different sex determination and sexual modes. In this dissertation, I explore aspects of sex in these species. K. marmoratus is the androdiecious and self-fertile member of the species complex with sequential hermaphroditism. In this species, the control of sex change from hermaphrodite to male is poorly understood. Individuals that were believed to be genetically identical could be raised in the same environment and change sex at drastically different times or not at all. Small fluctuations and variance in the hormonal profiles of individuals was thought to be a potential cause and while androgen dosing can lead to masculinization of both the gonad and the soma, it was not enough to maintain a permanent transition like what is seen in nature. In K. ocellatus, the obligate outcrosser of the K. marmoratus species complex, it was believed that they were using genetic sex determination to differentiate between males and the females that had hermaphroditic gonads. While we found strong evidence against heteromorphic sex chromosomes, all tests for homomorphic sex chromosomes came back inconclusive due to apparent K. hermaphroditus DNA contaminating the dataset. K. hermaphroditus, the self-fertile hermaphrodite species with exceptionally rare males, appears to be extending its range further and further south and/or hybridizing with K. ocellatus at rates previously underappreciated. The hermaphrodites of the Kryptolebias genus still hold many evolutionary and physiological secrets but can potentially be revolutionary to the understanding of vertebrate sexual development and evolution.
Photoredox-Active Tertiary N-Oxyammonium Reagents For Selective sp3 C-H Oxidative Functionalization
(2023) Hitt, Michael James; Vedernikov, Andrei N; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The C(sp3)-H bond functionalization under photoredox catalysis has been a topic of active research over two last decades. Photoredox catalysis involves the use of light to access catalysts’ excited states allowing for facile single electron transfer (SET) with a hydrogen atom transfer (HAT) agent precursor. One prominent HAT agent precursor is quinuclidine (Q), of which the active radical is the electrophilic radical cation (Q●+) able to abstract a hydrogen atom from a C(sp3)-H bond, so allowing for the bond functionalization. Q has been used by researchers since 2015 in the reductive photoredox catalytic C(sp3)-H functionalization (Chapter 1). In this work we focus primarily on the design of novel N-acyloxyquinuclidinium reagents with the goal of the development of new reaction protocols for the selective oxidative C(sp3)-H bond functionalization that utilize our new reagents under photoredox catalysis. In Chapter 2 we present our new catalytic system that allows for the selective oxidative C(sp3)-H trifluoroacetoxylation of donors of 1o, 2o and 3o benzylic C-H bonds using N-trifluoroacetoxyquinuclidinium trifluoroacetate that can be conveniently generated in situ by mixing quinuclidine N-oxide and trifluoroacetic anhydride in DCM solutions. Under photoredox catalyst under blue LED light, this reagent allows for the unique high-yielding (up to >99%) selective oxidative trifluoroacetoxylation of various (functionalized) alkylarenes used as limiting reactants (22 examples overall, including a pharmaceutical-derived substrate). The proposed reaction mechanism involves Q●+ as a highly selective HAT agent and benzylic carbocations resulting from oxidative radical polar crossover of transient benzylic radicals. In Chapter 3 we introduce a series of isolable N-aroyloxyquinuclidinium tetrafluoroborates (Q-Bz) that allow for the preparation of N-alkylimides in a first of its kind Ritter-Mumm type three-component oxidative imidation of donors of benzylic and cycloalkane C(sp3)-H bonds. In this reaction carbonitriles serve as the source of an imide nitrogen atom and a solvent, whereas the third reaction component, Q-Bz, acts as the oxidant, the source of HAT agents and one of two acyl groups of the imide products. All three reaction components can be varied. 33 different N-alkylimides were prepared using (substituted) alkylarenes as limiting reagents, with product yields up to 94%, and cycloalkanes taken in 3-fold excess with respect to the oxidant. The proposed reaction mechanism involves either Q●+ or aroyloxy radicals as HAT agents, depending on the identity of the aroyl group. Chapter 4 discusses the first example of a Balz-Schiemann – type C(sp3)-H fluorination of alkylarenes and cycloalkanes using N-aroyloxyquinuclidinium tetrafluoroborates (Q-Bz), with tetrafluoroborate anion as the source of the fluorine atom of the resulting alkyl fluorides. The proposed reaction mechanism involves either Q●+ or aroyloxy radicals as HAT agents. Chapter 5 discusses the use of N-trifloxypyridinium salts for Minisci type cross dehydrogenative coupling (CDC) of alkane C-H bonds and pyridine C(sp2)-H bonds. Some limitations and possible future development of this chemistry are presented. Finally, Chapter 6 gives a summary of the results of this work and suggests future directions for the advancement of oxidative C(sp3)-H functionalization chemistry using various N-oxyammonium salts as HAT agent precursors, oxidants, and co-reagents.
Ensemble Kalman Inverse Parameter Estimation for Human and Nature Dynamics Two
(2023) Karpovich, Maia; Kalnay, Eugenia; Mote, Safa; Applied Mathematics and Scientific Computation; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Since the widespread development of agriculture 10,000 years ago and particularly since the Industrial Revolution beginning in the 18th century, the coupled Earth and Human systems have experienced transformative change. The world's population and Gross Domestic Product have each increased by factors of at least eight in the last two centuries, powered by the intensive use of fossil energy and fossil water. This has had dramatic repercussions on the Earth system's stability, threatened by Human system activities such as habitat destruction, global warming, and depletion of Regenerating and Nonrenewable energy resources that increasingly alter environmental feedbacks. To analyze these changes, we have developed the second generation of the Human and Nature Dynamics model, HANDY2. HANDY2 is designed to simulate the dynamics of energy resources and population over the Industrial era from 1700 to 2200, flexibly incorporating real-world observations of population and energy consumption in an expanded suite of mechanisms that track capital investment, labor force allocation, class mobility, and extraction and production technologies. The use of automated Ensemble Kalman Inversion (EnKI) estimation for HANDY2's parameters allows us to accurately capture the rapid 20th-century rise in the use of phytomass and fossil fuels, as well as the global enrichment of Elites that puts pressure on natural resources and Commoners. EnKI-derived HANDY2 ensembles project that current world policies may lead to a collapse in the world's population by 2200 caused by rapid depletion of resources. However, this collapse can be prevented by a combination of actions taken to support voluntary family planning, lower economic inequality, and most importantly, invest in the rapid expansion of Renewable energy extraction.

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