cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.25549/usctheses-c127-625922
title: Flame synthesis of TiO₂ nanoparticles for ultrasensitive gas sensing

description: A new method is proposed to fabricate nanocrystalline titania (TiO₂) films of controlled crystalline size and film thickness. The method uses the laminar, premixed, stagnation flame approach, combining particle synthesis and film deposition in a single step. A rotating disc serves as a combination of substrate holder and stagnation-surface flame stabilizer. Disc rotation repetitively passes the substrates over a thin-sheet, fuellean ethylene-oxygen-argon flame doped with titanium tetraisopropoxide (TTIP). Convective cooling of the stagnation surface keeps the substrate well below the flame temperature, allowing thermophoretic forces to deposit a uniform film of particles that are nucleated and grown via the flame stabilized adjascent to the surface. The particle film grows typically at a net rate of ~1 µm/sec. The film is made of narrowly distributed, crystalline TiO₂ particles several nanometers in diameter and estimated to be initially ~90% porous. Analysis shows that the rotation of the stagnation surface does not reduce the stability of a stagnation flame, nor does it affect the fundamental chemistry of particle nucleation and growth that occurs between the flame and the stagnation surface. ❧ Titania particles produced using this method are phase-pure single-crystal anatase with a narrow and controllable size distribution with median diameter ranging from a few nanometers to around 20 nm, characteristics desirable in the production of highly sensitive and selective gas sensors. Conductometric gas sensors were fabricated using this new technique by repeatedly translating interdigitated electrodes over a TTIP doped flame. The conductometric response of TiO₂ to surface reactions is a result of the gain and loss of oxygen ions and the corresponding change in electrical resistance arising from the change in titania stoichiometry. For example, a reducing gas reacts with surface oxygen, removing it and enriching the free electron concentration, thereby changing the resistance of the nanoparticle network. Networks made of smaller particles—with a greater surface area to volume ratio—offer a twofold advantage: first, they offer a greater number of surface sites for surface reactions and second, the electrical effects taking place at the surface of the semiconductor are more pronounced. For these reasons, the sensitivity and selectivity of the gas sensing films prepared by the flame technique is expected to improve notably compared to existing film preparation methods. In this dissertation work, the conductometric gas sensing limits of stagnation flame synthesized TiO₂ nanoparticle films to CO were examined and compared to commercial titania. Flame deposited electrodes show good sensitivity to carbon monoxide (CO) at concentrations as low as 5 PPM as well as long term stability with reproducible signals.
DOI: 10.25549/usctheses-c127-635923
title: A grounded theory study on the academic success of undergraduate women in science, engineering, and mathematics fields at a private, research university

description: This grounded theory study revealed the common factors of backgrounds, strategies, and motivators in academically successful undergraduate women in science, engineering, and mathematics (SEM) fields at a private, research university in the West.  Data from interviews with 15 women with 3.25 or better grade point averages indicated that current academic achievement in their college SEM fields can be attributed to previous academic success, self awareness, time management and organizational skills, and maintaining a strong support network. Participants were motivated by an internal drive to academically succeed and attend graduate school. Recommendations are provided for professors, advisors, and student affairs professionals.
DOI: 10.25549/usctheses-c127-644309
title: Demonstratives in logic and natural language

description: In this dissertation, I provide (i) a semantics for simple and complex singular demonstratives in English, (ii) a theory of how the reference of a referential use of a singular demonstrative is determined in the context of the use, and (iii) a logic of demonstratives that allows us to accurately represent our reasoning with demonstratives. The last project requires rejecting David Kaplan's original definitions of validity and logical truth for languages containing context-sensitive expressions; according to the alternative I propose, a sentence $\phi$ can be logically true, or an argument valid, relative to one context but not another. This allows us to explain why we can use an argument containing demonstratives in one situation and seem to reason well, but use the same argument in a different situation and seem to reason poorly. Crucial to this view is to recognise the distinction between referential and non-referential uses of demonstratives, where referential uses are distinguished by a particular kind of referential intention with which the speaker uses the demonstrative. The semantic theory I propose accounts for both standard referential uses and deferred referential uses of demonstratives, while preserving the classic intuitions about direct reference for standard uses. I defend this semantic proposal against several objections and compare it to the most important alternatives currently available in the linguistic and philosophical literature.
DOI: 10.25549/usctheses-c127-646610
title: New England merchants, the China trade, and the origins of California

description: The central concern of this dissertation is how Americans thought the China trade worked, and how trade with China drew Americans into the Pacific and to California not long after Independence. It is about communication and the construction of knowledge, since Americans who traded with China, or thought about trading with China, did not have perfect knowledge of the world in which they lived. Rather than manifest destiny, the desire to trade with the world, and particularly with China, drove the earliest American ventures into the Pacific. Before the bombast of Manifest Destiny or the frenzy of the California gold rush, Americans were already interested in the Pacific generally and in California specifically, as an outgrowth of their desire to trade with China.
DOI: 10.25549/usctheses-c127-656449
title: Year two study of a community, school, and university partnership for urban schools: identifying resources which support the academic achievement for African American students

description: Educational reform in large urban school districts has produced little success among African American students. From the implementation of Brown vs. Board of Education Topeka (1954) to NCLB (2001), academic achievement of African American students have historically performed below their white and Asian counterparts. The effects of imposed segregation, discrimination and under resourced educational institutions where students of color predominate have negatively impacted the achievement of African Americans. In order to transform education to support equitable opportunities for African American students and other ethnic minority students to learn, education must undergo a re-culturation process that takes into account how to change the norms, behaviors, language, expectations, and modes of interactions among the people who work in schools. This process can be supported through community-school-university partnerships. Researchers will use a case study to investigate what ongoing processes, including co-construction, does a community-school-university partnership demonstrate as it continues to work toward school transformation following its first year of operation; including strategies to overcome the barriers that persist to co-construction. Also the study seeks to examine in what ways do the types of resources resulting from the community-school-university partnership contribute to the academic achievement of African American students.
DOI: 10.25549/usctheses-c127-657827
title: Benthic marine ecological shifts and carbonate diagenetic effects surrounding the end-Permian and end-Triassic mass extinctions

description: The Early-Mid Mesozoic was a time of broad ecological and geochemical change punctuated by two major biotic and environmental crises - the end-Permian and end-Triassic mass extinctions. In the wake of the end-Permian mass extinction, the Modern Fauna emerged as the dominant taxonomic group. Herein, bioclastic accumulations are used to track ecological dominance across the Early Mesozoic, particularly in the Middle Triassic aftermath of the end-Permian mass extinction interval. Additionally, a literature search is used to trace the waning ecological importance of the crinoids, constituents of the Paleozoic Fauna, through the Mesozoic. Despite diminished diversity, the Paleozoic Fauna regained ecological dominance in the post-extinction world. After a Middle Triassic comeback, the crinoids persisted as ecological dominants through the Jurassic before their ecological twilight in the earliest Cretaceous. The timing of these patterns does not fit the suggestion of an ecological upheaval caused by the end-Permian mass extinction, but rather points to other potential factors such as the Mesozoic Marine Revolution. ❧ The Triassic-Jurassic (T-J) boundary saw the rapid emplacement of a large igneous province resulting in a major carbon cycle perturbation, perhaps even inducing ocean acidification. The T-J boundary interval is used as a case study to explore how to identify ocean acidification in deep time. Thus far, the T-J boundary record is consistent with an acidification scenario. Fieldwork at multiple, geographically disparate boundary intervals shows an abundance of early diagenetic carbonate. In particular, unusual layers of aragonite fans which grew just below the sediment-water interface are identified globally. Abundant early diagenetic carbonate suggests that the sub-seafloor may have been a locus of carbonate precipitation across the T-J boundary interval and that the early diagenetic realm is a carbonate sink of unknown size and variability.
DOI: 10.25549/usctheses-c127-663206
title: Development of flexible polymer-based MEMS technologies for integrated mechanical sensing in neuroprosthetic systems

description: The field of BioMEMS is becoming increasingly important to neuroprosthetic technologies by enabling communication with neurons at ever smaller scales. Among the many challenges facing these technologies, perhaps the largest are maintaining biocompatibility and understanding the mechanical stability and interaction between neuroprosthetics and tissue. ❧ Retinal prosthetics in particular are at the forefront of these challenges. Their impact on society, however, cannot be understated. Restoring “sight” to those blinded by devastating retinal diseases is a true marvel of modern technology. In an effort to improve and ultimately restore even more capabilities to those impaired, a better understanding of the interface between these implants and the human body is required. This dissertation presents the development of a novel sensing paradigm utilizing electrochemically-based transduction technology that is leveraged for the measurement of pressure between Parylene-based epiretinal implants and retinal tissue. The core sensing principle and sensor technology are developed for real-time quantitative measurements. An overview of bioMEMS techniques, tools, and materials is provided in chapter 2 with an emphasis on Parylene as a substrate for realizing not only the neuroprosthetic implants, but the technology to instrument them. Chapter 2 discusses the fundamentals of electrochemical impedance measurements and their application as a relatively new transduction paradigm within microdevices. In chapter 3 a series of design iterations are presented that chronicle the development of a suitable sensor technology capable of integrating with Parylene-based epiretinal implants. Several key challenges were overcome including the fabrication methods necessary to realize fluid-filled microstructures with pressure transduction capability. Chapter 3 presents results of ex vivo implantation studies using instrumented sensor arrays to visualize the pressure distribution across the implant surface. These results provide the first real-time quantitative assessment of interfacial pressure produced during implantation of an epiretinal implant. Finally, chapter 4 discusses additional potential avenues of application including instrumentation of intracortical shanks for interfacing with the brain. Several addition exciting applications are also presented and provide examples of the potential for impedance-based microtechnologies.
DOI: 10.25549/usctheses-c40-151801
title: Social work intervention on neonatal infant intensive care units
DOI: 10.25549/usctheses-c40-152596
title: An experiment in task-centered casework
DOI: 10.25549/usctheses-c40-328056
title: Comparison of overall vs individual vehicular delay using macroscopic routing

description: In this paper, a macroscopic routing method is applied to two different traffic routing scenarios. The macroscopic method seeks to route vehicles in such a way that minimizes the travel time for the entire transportation network, while a traditional routing method seeks to minimize an individual’s travel time. This method was applied to a model road network that represents a real portion of the highway system in Los Angeles County. Data gathered from the California Department of Transportation creates a relationship between the number of vehicles on those highways to the speed that those vehicles are traveling. A program was created that uses that data to generate an optimal routing scenario for the entire traffic network when given a certain number of vehicles on the roadway. The results from this program show that taking some vehicles off of their fastest path, and putting them on a slower path, can save time and reduce congestion for the entire network. The congestion reduction achieved in the two scenarios tested by this program is about 90% depending on the number of vehicles on the network. Additionally, the total travel time for the entire network is reduced by as much as 35% in these scenarios. Finally, the results show that all vehicles, even the ones rerouted onto slower paths, experience a shorter travel time than they would have on the original, congested path. It should be noted that all of these results were obtained using a program that has a number of limitations, including being unable to account for congestion build-up over time.
DOI: 10.25549/usctheses-c127-621191
title: While waiting for immigration reform

description: Currently, it is estimated that there are approximately eleven million undocumented immigrants from around the world living in the United States, the vast majority of them of Hispanic descent. In the last two years, this entire population has faced new multiple challenges that have been making it more difficult to live in this country because of their legal status. Since the federal government has failed to produce comprehensive immigration reform, undocumented immigrants have to deal with tremendous pressure from lawmakers at the state levels, most of which are enacting legislation aimed at this group of people by criminalizing the very act of living in certain states across the country. ❧ Despite the barriers that federal immigration reform is facing in the current political climate in this country, it is not an impossibility, but while we lawmakers decide, many immigrants suffer lasting consequences. Psychologically, the new state laws and the discussion itself which is political in nature are taking a huge toll on illegal families. ❧ This paper examines the emotionally charge subject of immigration in the United States. A federal comprehensive immigration reform bill could take many years before it is passed. According to some academics and immigration experts around the country, it may take up to ten years before the U.S. Congress overhauls our current immigration system. At the same time, this paper researches a viable option, a practical temporary solution so solving a problem, short-term. It address what can be done right now to improve a very precarious situation affecting the undocumented immigrants, while at the same time, allowing the government to benefit and profit from this community that lives in fear of persecution and deportation.
DOI: 10.25549/usctheses-c127-641549
title: Lived experiences of gay men with HIV; intersections of portraiture, narrative and engagement

description: This qualitative research utilizes narrative as a way to explore the experiences of five gay men living with HIV. Their membership in this marginalized group presents particular challenges to  engagement in meaningful activities or occupations. The innovative methodology known as portraiture is used, drawing on phenomenological and ethnographic foundations. This method joins the empirical and the aesthetic; creating a narrative that brings together the careful description of good ethnography with the evocative resonance of fine literature. The interviews and participant observations in the study are guided by portraiture; while the additional lenses of narrative and experience contribute to the thematic analysis. Through these complementary approaches, a narrative portrait of each man is created and emergent themes are presented.  These themes include uncertainty with medications and side effects which serve as constant reminders of their HIV status. Their narratives include a rich diversity in self understandings deeply intertwined in their coming out as gay, the awareness of their HIV status, and their experiences of their body. The development of multiple identities is an ongoing process that is situated in a larger context of social relatedness. The men search for ways to make sense of the death of friends, fears of their own sickness and death, and their possible future lives with HIV. These experiences of loss are expressed, negotiated, and narrated through the appropriation of metaphors and engagement in social action. The use of narrative itself, becomes a cultural resource for these men. The importance of aesthetic representations and the power of performance is emphasized through a microanalysis of a ❧ particular concert experience. The intersections of portraiture, narrative and engagement provide a deeper understanding of the complexity of the lived experiences of these men.
DOI: 10.25549/usctheses-c127-643541
title: Fluid dynamics of sessile drops in shear flows

description: The shear flow dynamics of a viscous liquid drop placed in another fluid medium is analyzed in the Stokes-flow regime. This study is motivated by investigations on protein crystal growth for which it is known that shear flow in the protein solution affects the nucleation rate. It is of interest to be able to generate and control shear flow in the sessile-drop geometry which is commonly used for crystal growth and protein aggregation studies. While drops for such experiments are usually of the spherical-cap shape, the enormous analytical complexity has led us to first deal with a two-dimensional drop with linear shear in the external medium, i.e., the cylindrical equivalent of the cap. With the bipolar coordinate system, the circular interface can be exactly identified by constant value of one of the coordinates, and lends itself to satisfying the relevant continuity conditions at the gas-liquid and the solid-liquid interfaces of the system. The second case of a three-dimensional axisymmetric sessile drop with extensional flow shear is analyzed under toroidal coordinate system with the same advantage of fitting gas-liquid interface as bipolar coordinate system. While these two cases rely on the mechanical shear, a third case of electrostatically driven flow applied to a hemispherical drop on a solid surface is also considered. The exact solutions within the framework of Stokes flow of three cases are developed, and the flow field and shear stress distribution are rendered in this study. Some major effects of fluid properties, such as viscosity ratio, and dielectric constant ratio, to shear stress distributions are discussed. It is expected that the quantitive evaluation of the parameters governing shear will provide useful information for controlling shear rate in a sessile drop. The analysis would be helpful in the design of experiments where direct measurement of shear is generally intrusive and possibly disruptive to other sensitive physicochemical processes such as protein nucleation.
DOI: 10.25549/usctheses-c127-666062
title: Convergent morphological evolution in hyenas and dogs: the relationship between form and function

description: The past 65 million years of evolution in carnivoran mammals exhibits numerous cases of convergence in ecomorphologies, stereotypical morphologies that represent unique ecological adaptations. Such examples demonstrate the iterative adaptation of distantly related lineages to a few lucrative hypercarnivore (meat specialist) niches. To explore the mechanistic explanations underlying convergent evolution of ecomorphologies, this dissertation documents and reviews recent advances in our understanding of feeding specializations in one particular hypercarnivore niche, the bone-crackers. Bone-cracking specialists evolved at least three times in Carnivora, in the hyaenid, percrocutid, and borophagine canid lineages. These studies in the evolutionary changes of skull shape, enamel microstructure, enamel microwear, and craniodental biomechanics of hyaenids and borophagine canids show that the suite of adaptive morphological characters commonly found in the bone-cracking functional complex evolved in a mosaic manner. Microstructural changes in the enamel were related to increased durophagy as inferred from microwear analysis, followed by continuous skull shape changes toward increased robustness and strength. Subsequently, skull stress dissipation patterns became adapted to handle mechanical demands of durophagy, followed by a split into even more mechanically efficient terminal species versus body size specialists. An updated definition of bone-cracking specialization is presented, and implications for more general understanding of feeding specialization are discussed. An ordered evolutionary sequence of adaptive traits in a functional complex represents a flexible mode of evolution that can accommodate different degrees of specialization in increasingly durophagous lineages, and may serve to explain similar adaptations in other carnivorans and non-carnivoran mammals.
DOI: 10.25549/usctheses-c127-670493
title: An inquiry to assess the impact of specificity on the option to terminate

description: Real Options Reasoning is slowly making inroads into the project evaluation landscape either as a quantitative technique or as a heuristic for managerial thinking. While the extant literature is focused on quantitative analysis and the valuation of real options, there is a concerted effort to diagnose the behavioral underpinnings of real options reasoning. This dissertation is in the spirit of the latter, wherein, the objective is to understand the impact of providing specific information to decision-makers is measured under varying levels of project completion. The results show decision-makers value the specificity of information presented, but nevertheless seek completion.
DOI: 10.25549/usctheses-c127-672017
title: Pose estimation for in-hand objects

description: Estimation of 6D pose of a known object in robot hand is traditionally done by using vision or range sensing. Such methods perform badly in cases when data is sparse or incomplete. This thesis presents an approach to estimate the pose of a known in-hand object by using range sensors and force torque sensors in order to overcome limitations of using range sensors alone. The proposed approach uses a novel method to combine information from the two sensors using `mass-points'. The method is validated by experiments with a Barrett WAM arm and shows significant improvement in results when compared to popular method.