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Collection Description

Collection of student theses and dissertations from as early as 1939, but mainly from 2010 to present.

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Volcanic and nonmarine stratigraphy of southwest Isla Tiburon, Gulf of California, Mexico
Scale of accompanying map 1:12,000, Title of accompanying map on Plate I: Geologic map of SW Isla Tiburon, Gulf of California, Mexico., Title of accompanying diagram on Plate II: Cross sections F-F' and X-X' of SW Isla Tiburon, Gulf of California, Mexico., Latitudes and longitudes are given for each corner of the map., The base map was developed with aerial photographs provided by CETENAL. Scale of the geological map is: 1:12,000. Coordinates for the geological map were estimated using Google-Earth-satellite imagery., Southwestern Isla Tiburon (SWIT), Gulf of California, Mexico, is an area approximately 30 square kilometers, containing sedimentary and volcanic strata which are predominantly Early and Middle Miocene in age. A fossiliferous marine conglomerate on SWIT is believed the oldest marine deposit in the Gulf of California region, and supports the conclusion that a marine protogulf existed 15 to 8 Ma. K-Ar ages from this and previous studies provide a time constraint on the deposition of the marine conglomerate and the overall volcanic history of SWIT. Dips of beds suggest listric faulting occurred throughout much of the Miocene: Redbeds dip 40-50°N, basalt flows 23ºN, conglomerates 20ºN, and an ignimbrite 5ºNW. A fault along Arroyo II displays right-lateral, strike slip and may be related to the La Cruz Fault which trends NW-SE along the southwest end of the island. In the late Cretaceous-early Tertiary, SWIT was part of the arc system along the western margin of the North American Plate. At this time, SWIT was adjacent to northeastern Baja California. In the Early Miocene Basin and Range extension led to the formation of small trough-shaped basins, and fluvio-lacustrine deposition resulted. Volcanic and roof pendant debris was shed into small basins on SWIT from the north. At 21-19 Ma andesitic volcanism occurred and a volcanic collapse structure formed which was later filled with andesitic lahar. The andesitic magma apparently formed out of a primary melt of the lower crust. From 19-16 Ma basaltic volcanism was dominant on SWIT and both tabular flows and ring dikes developed. The basalt of SWIT is alkalic olivine-augite, is high in incompatible elements and is similar to Early and Middle Miocene basalts of the Imperial Valley-northeastern Baja California region. Dacitic pyroclastic volcanism followed basaltic volcanism on SWIT, and between 14 and 11 Ma a protogulf developed which was filled with pyroclastic and conglomerate debris. At 11 Ma volcanism on SWIT became predominantly rhyolitic. First, rhyolite ignimbrite extruded, and, in the late Miocene, rhyolite pods, coulees, and crystal dikes developed. In the early Pliocene a dacitic ignimbrite with a tholeiitic character extruded reflecting conditions associated with modern Gulf of California rifting and seafloor spreading., San Diego State University
Voltammetry detection of non-electroactive neurotransmitters using glassy carbon microelectrodes – case of glutamate
Detection of neurotransmitters through voltammetry is a common technique in NeuroMEMS (neural microelectromechanical systems). Dopamine and serotonin are electroactive neurotransmitters and relatively easier to detect through electrochemical ways. Other non electroactive neurotransmitters such as glutamate, lactate acid, and gamma- Aminobutyric acid (GABA) are challenging to detect without modifying the electrode surface. Electrochemical methods, such as fast-scan cyclic voltammetry (FSCV), are used to detect electroactive neurotransmitters and molecules in-vitro. To detect non-electroactive molecules, must be reduced into electroactive molecules. Glassy carbon microelectrodes (GC) have shown to be a promising material in neuroscience, specifically electrochemistry, with a capability of detecting electroactive and non-electroactive species such as glutamate. In this work, we demonstrate immobilization of glutamate oxidase (GluOx) on a probe with a four-electrode array and subsequently using FSCV. We focus on some current strategies for glutamate probes immobilization on the electrochemical transducer's surface, such as covalent bonding, glutaraldehyde, bovine serum albumin (BSA), and GluOx reaction on the electrode surface for specific interaction with its corresponding glutamate target. Using glutaraldehyde, BSA, and glutamate oxidase, we could detect an electrochemical reduction of O2 to H2O2. The immobilization matrix of GluOx on the GC electrode acts as a barrier that allows the electrode to give supporting electrons. By functionalizing bare GC electrodes, we have shown the detection of glutamate, a non-electrode molecule. Through the chemical reaction with an enzyme happening at the surface of the electrode and cyclic voltammetry, we were able to show the chemical reduction of non-electroactive molecules., San Diego State University
Voluntary Smoking Restrictions: Promises and Challenges in Protecting Nonsmokers
Includes bibliographical references., Background: Adoption of voluntary smoking restrictions continues to increase in US private households and the hospitality industry. Unfortunately, discrepancies regarding their scope, implementation, and enforcement exist, potentially compromising their impact on lowering nonsmokers' exposure to tobacco smoke toxicants. The objective of this dissertation was to examine the role of voluntary smoking restrictions on reducing secondhand smoke (SHS) and thirdhand smoke (THS) exposure of nonsmokers in private settings. Methods: Data for this dissertation were taken from three separate existing studies conducted in San Diego, CA, examining (1) SHS exposure among pre-teens (Chapter 2, N=388 families), (2) THS pollution of private homes (Chapter 3, N=100 homes), and (3) smoking policy of rental car companies (Chapter 4, N=6 national companies with N=125 local branches). Data for Chapter 2 were examined using multinomial logistic regression to examine the circumstances under which parent/child dyads agreed on a smoking ban. Data for Chapter 3 were examined using multinomial logistic regression to investigate the role of smoking restrictions and behaviors on THS pollutants in dust and on surfaces. Data for Chapter 4 were examined to describe smoking policies at the corporate level and explore their implementation in local branches. Results: In Chapter 2, 18.3% of dyads disagreed on the presence of a complete smoking ban. Factors that contributed to this disagreement included residents' smoking behaviors and parents inconsistently asking visitors to smoke outside. In Chapter 3, home smoking rules and compliance with rules were found to affect indoor smoking rates, which in turn influenced THS contamination in dust and on surface. Other factors that impacted THS in dust were home features and remediation efforts. In Chapter 4, four of the six national rental car companies reported an official smoking policy. Lack of training and communication to local branch staff resulted in poor implementation of the official company smoking policies and failure to protect customers from THS exposure. Discussion: Private indoor settings remain the primary location for exposure to tobacco smoke pollutants for nonsmokers. Voluntary smoking restrictions in private settings can reduce THS contamination and exposure. Residents and management need to define, communicate, and consistently implement smoking restrictions to ensure a true smoke-free environment.
Vortex generation at the wake of an impurity in a quantum superfluid
We investigate obstructed flow in a quantum superfluid. Utilizing a flattened 2D Bose-Einstein condensate whose dynamics are prescribed by the Gross-Pitaevskii equation in a co-moving reference frame, we show that the superfluid Reynolds number characterizes the wake patterns behind the obstacle. Furthermore, by combining a fringe damping region and a boundary condition derived to emulate far-field conditions, we develop stable absorbing boundary conditions for a 2D BEC that allow simulations in the supersonic flow regime. The absorbing boundary conditions are tested for a wide range of situations whereby multiple vortices and radiation waves are succesfully absorbed at the boundary. Additionally, these absorbing boundary conditions, are very straightforward to implement., San Diego State University
Vortex interaction in polariton Bose Einstein condensates
Bose Einstein condensation (BEC) is a unique state of matter where bosons coalesce to the same (quantum) wave function. Because of their unique properties, BECs allow the possibility of studying quantum dynamics at the macroscopic level. This leads to many exciting applications in gyroscopes, interferometry, and quantum computing. Exciton-polariton systems represent a novel realization of BEC at relatively high temperatures (in contrast with standard BEC that need to be help at nano Kelvin temperatures). In two dimensions, vortices represent the basic/prevalent BEC solutions which are currently being explored both analytically and experimentally. The goal of our work is to study the dynamics and interactions between vortices in exciton-polariton BECs and in particular to (a) showcase the difference between vortex-vortex interactions in standard and exciton-polariton BECs and (b) to cast reduced particle-like equations for vortex-vortex interactions. Our starting model consists of the standard BEC model consisting of the nonlinear Schrodinger equation (NLS), a partial differential equation ̈ (PDE), with no external potential nor loss/gain sources (the vanilla case). We study the vortex steady state and the interaction between two same-charged vortices using a combination of optimization, finite differencing, and Mod-Squared Dirichlet/Laplacian-zero boundary conditions. The study of the vanilla NLS case serves both as a testing ground for our numerics and a quantitative measurement of how vortices behave in the absence of gain/loss or external influences. We then extend the vanilla NLS to model exciton-polariton BECs by incorporating gain and loss terms that are intrinsic to these systems. Due to the presence of gain/loss, vortices inherently develop a spiral phase that is responsible for the spiraling out of vortex-vortex pairs (trait that is absent in the vanilla case where two same-charge vortices just rotate in a circular motion). By phenomenologically fitting the corresponding dynamics for the exciton-polariton case, we are able to obtain a reduced ordinary differential equation (ODE) model that accurately describes the interactions between two (or several) vortices interactions as if they were particle-like entities., San Diego State University
Vortex rings in quantum fluids
We study the dynamics of vortex rings in Bose-Einstein condensates (BECs), the coldest known matter in the universe. For appropriate conditions (dilute enough and low enough temperatures), a BEC behaves as a quantum superfluid modeled by the nonlinear Schrödinger equation. Using the Bio-Savart law for standard fluids, we show how the interactions between coaxial vortex rings in the 3D superfluid can be approximated by coupled particle equations on their positions and radii. In particular, we study the leapfrogging behavior of coaxial vortex rings with equal charge using the particle model and compare it favorably to the full 3D dynamics of the original BEC model. Conditions for the existence of leapfrogging behavior are studied, as well as its stability. An extension of a GPU-accelerated code is developed to study the dynamics of vortex rings confined in a parabolic magnetic parabolic trap. In particular, we focus on the evolution of unstable stationary states, vortex ring precession around stable stationary states, and leapfrogging behavior., San Diego State University
Vulnerable populations and tobacco control in Latin America
Tobacco is responsible for over 7 million deaths every year. Various policies through the WHO Framework Convention on Tobacco Control contributed to reduce the burden of tobacco consumption with important heterogeneity across regions and population subgroups. Latin America is the most unequal region in the world, where health, social, and economic disparities likely result in a differential impact of tobacco control policies between and within countries. This dissertation explores the trends in tobacco smoking in Latin America from a multi-country perspective as well as through country specific analyses. Specifically, we analyzed trends in income inequalities regarding smoking in Mexico and evaluated the effectiveness of a comprehensive tobacco control policy implemented in Uruguay targeting adolescents and young adults. Furthermore, this dissertation is characterized by a focus on disparities in relation to gender, age, and income. Nationally representative surveys were the main sources of data, and the methods employed quasi-experimental designs, decomposition analyses, and estimation of income inequalities, among others. Results showed important heterogeneities in this region regarding inequalities in cigarette consumption by gender, age and income. Findings from eleven Latin American countries showed that over the past 20 years, teenagers did not follow the smoking trends observed among adults, with marked differences across gender groups. We also found that adult women in the lowest income categories in Mexico showed higher reductions in tobacco smoking during a period of sharp increase in cigarette prices, as compared to men, and to women in higher income categories. Finally, a comprehensive tobacco control policy was shown to be highly effective in reducing smoking prevalence among the youth in Uruguay. The characteristics of the region and the findings of the study support the need to continue expanding tobacco control policies and research in Latin America with a focus on aligning policies to regional, gender and income differences to achieve maximal public health impact., University of California San Diego; San Diego State University
Wallrock mass and volume change during emplacement of the Middle Jurassic Emigrant Gap composite pluton, Sierra Nevada, California
Previous studies by Dr. Gary H. Girty and students at San Diego State University have quantified element mobility patterns within metamorphosed mudstones of the post-Cambrian and pre-Upper Devonian Shoo Fly Complex, northern Sierra Nevada, California, as they are traced from outside to inside the aureole of the Middle Jurassic Emigrant Gap composite pluton. Results of these previous studies indicate that mudstone mass, on average, decreased 5.6 +/- 4.7% during development of the contact metamorphic aureole. Loss of mudstone mass was apparently facilitated by the removal of SiO2 under elevated fluid-to-rock ratios, and resulted in an estimated volume strain of -7.1 % +/- 5.0%. These results have lead several investigators to suggest that contact metamorphism may play an important space making role in the emplacement of magmatic bodies at mid-crustal levels. None of this previous work addressed the fate of the removed SiO2 mass. Hence, the purpose of this thesis is to address the question: Was silica mass removed from the aureole, or, was it simply transferred from mudstones to sandstones, both lithologies being prevalent throughout the Shoo Fly Complex? Data presented in this thesis show that during the development of the aureole, sandstone mass as well as volume, on average, increased 13.1 +/- 10.1% and 14.6 +/- 10.2% respectively. The mechanism by which silica mass was introduced to and transferred within the aureole is unclear. However, several observations point to at least two possible mechanisms. First, the fact that all samples analyzed during this and previous studies were absent of any traces of quartz veinlets implies that the transfer of silica mass into sandstone beds must have been within a thin, sub-microscopic, fluid phase around grain boundaries. Such a fluid phase is needed to allow transport of silica over lengths greater than those typical of solid-state diffusion which commonly occurs at the atomic level to scales measured as fractions of individual crystals. Second, the ubiquitous presence of quartz veins and veinlets within mostly sandstones, and, to a lesser extent, mudstones indicates that silica-rich fluids were probably moving through the aureole during its development. Many such veins have strikes that are at a high angle to the contact-parallel foliation and layering within the aureole. Such orientations suggest that the veins may have infiltrated along extensional cracks as layering was flattened and distended against the northwestern contact of the pluton. There is no evidence gathered during my research to support the idea that volume loss driven by removal of elemental mass within wall rocks through elevated fluid-to-rock ratios played a role in making space for the Emigrant Gap pluton., San Diego State University
Warcare economies: Countering violent extremism in San Diego
In 2011, the United States began its first iteration of Countering Violent Extremism (CVE), a new counterterrorism surveillance program developed under Obama-liberalism aimed at permeating Black, Arab, and South Asian Muslim communities. The goal was bridging the relationship between State and Community in which the Department of Homeland Security (DHS) and affiliated bodies would directly build rapport with communities in hopes of recruiting informants as well as using police-community partnerships to observe and restrict political resistance to state violence. While CVE has generated extensive debate for its domestic perpetuation Islamophobia, xenophobia, anti-Black racism, classism, and Zionism, the invisibilized and often omitted components of CVE are its transnational counterparts in countries abroad with direct links to US militarism and counterinsurgency operations all around the world. Today, CVE has provided millions of dollars to community organizations, universities, non-profits, police departments, intelligence agencies, and armies around the world all geared toward enacting programs securing intelligence on target communities. City Heights and El Cajon are key CVE sites identified by the DHS. City Heights is known for its large East African refugee populations. Similarly, El Cajon, nicknamed “Little Baghdad”, is rife with Syrian and Iraqi refugees displaced by US imperialisms of the last 20 years- this number also includes a large number of Palestinian Muslims displaced by Zionism and US imperialism. On the transnational level, CVE programming and US military operations simultaneously target Somalia, Kenya, Syria, Iraq, and Palestine. Thus, CVE relies on what I call warcare economies: the manipulation of neoliberal “care” to enact surveillance, coerced capitulation, and ultimately circumvent political movements challenging ongoing militarism and repression. This thesis situates this broader transnational model of warcare in San Diego by exploring the role of the University of San Diego in enacting CVE counterinsurgency in San Diego and countries around the world. It will identify the rhetoric put forth by their CVE programming and examine the material impacts this programming has on various communities- either refugees in San Diego and community members impacted in East Africa and the Levant. Ultimately, this thesis aims to highlight the symbiotic relationship between militarization, humanitarian work, and counterinsurgency., San Diego State University
Was Wright Wrong? An Examination of Airfares in Dallas After Partial Repeal of the Wright Amendment
Includes bibliographical references (pages 63-65)., In 1980, Congress passed the Wright Amendment — legislation that placed strict limitations on commercial air traffic into and out of Dallas Love Field. The primary component of this law mandated that most flights into and out of Love could only serve airports within Texas and the four adjacent states of Arkansas, Louisiana, New Mexico, and Oklahoma. Later revisions to the law added states to the allowable area; Alabama, Kansas, and Mississippi were added in 1997 and Missouri was added in 2005. In 2006 a two-stage plan for repeal of Wright was enacted that immediately abolished some service limitations followed by the elimination of all current restrictions in October 2014. This paper uses aviation data from the U.S. Department of Transportation in a difference-in-differences model to examine how airfares changed after policy revisions on routes between the Dallas region and cities in the states added in 1997 and 2005 as compared to control cities in unaffected states. A frame of contestable markets theory is used to postulate how incumbent airlines in a market may react to the policy changes based on the likelihood of an immediate competitive threat from another airline who could easily start service on the route but had been legally prohibited from doing so. Multiple panels of control cities and economic data are used to check estimates for robustness. The results for the states added in 1997 are mixed, with most estimates indicating no significant change to fares after the policy was enacted, even if a new competitor was able to start the route. However, one city did show significant fare declines in some models. In contrast, findings for the 2005 change suggest unambiguously that fares fell significantly on routes where new competition was likely.