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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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A geo-spatial analysis of the assocation between craft breweries and crime in Vista, California
While the connection between liquor and crime has been empirically understood, there is a lack of attention to the relationship between the craft brewery industry and crime. Craft beer has exploded in national popularity since the turn of the twenty first century. This paper looks at proximity crime in the 0.2 mile catchment areas surrounding each brewery in Vista, California in 2016. Calls for service were utilized to measure crime. Specifics about the type, amount, and placement of service calls help recognize the relationship between the craft brewery industry and proximity crime. Demographic population data provides a contextual understanding for the neighborhoods that the breweries exist in, and specific environmental factors of the breweries themselves help address disparities of service calls experienced between the 16 breweries in the study. Overall, traffic service calls were most likely to be associated with alcohol. The demographic and environmental factor that was most strongly correlated with service call density was the number of liquor outputs in a catchment area.
A geochemical and isotopic study of the youngest lavas from the islands of Upolu and Savai'i, Samoa
We report major and trace element abundances and Hf, Pb, and Nd isotopic ratios for eight of the youngest rejuvenation stage lavas from the Samoan Islands of Upolu and Savai'i. The extensive and voluminous amount of rejuvenation stage volcanism on the Samoan islands, especially on the islands of Savai'i and Upolu, has made these islands key in the understanding of rejuvenation magmatism. The six lavas from Upolu are basanites, whereas the two lavas from Savai'i are alkali basalts. With the exception of one basanite with 7.4 wt. % MgO, all of the samples are relatively primitive (MgO = 10.5 to 12.2 wt. %) and show little evidence of fractionation beyond olivine control. However, variations in major element abundances at a given MgO value indicate changes in the parental melt composition. This interpretation is confirmed by wide variations in ratios of incompatible trace elements (e.g., Nb/La or Ce/Yb). On a primitive mantle normalized trace element diagram, the lavas have relatively constant, low abundances of heavy rare-earth elements (e.g., Yb) due to the presence of residual garnet in the mantle source region. The _Nd (-0.26 to +2.93) and εHf (+3.82 to +7.17) values, and Pb isotope ratios (e.g., ___Pb/___Pb = 18.57-18.88) vary significantly but plot within the range of published data for rejuvenation stage lavas from these islands. On a plot of εNd vs. ___Pb/___Pb, the new Upolu and Savai'i analyses make a distinctive positive correlation that overlaps with previous analyses of rejuvenation stage lavas from these islands. Interestingly, this trend is distinct from the ones defined by many of the purported Upolu and Savai'i shield stage lavas. These data will help to better understand the origin of rejuvenation stage magmatism., San Diego State University
A geochemical evaluation of enhanced in-situ bioremediation of chlorinated ethenes in groundwater
Includes bibliographical references (page 51), Sites impacted with chlorinated solvents present unique technical challenges when compared to most other groundwater contaminants. Chlorinated volatile organic compounds (CVOCs) such as such as tetrachloroethene (PCE), trichloroethene (TCE), or 1,1,1- trichloroethane (1,1,1-TCA) generally do not degrade naturally in the environment. Therefore, more aggressive source depletion methods such as enhanced in-situ bioremediation (EISB) may be implemented to treat the groundwater plume. EISB involves injection of an electron donor to promote reducing conditions followed by inoculation of groundwater with dechlorinating bacteria. When conditions are favorable, the dechlorinating bacteria sequentially remove chlorine ions from the chlorinated solvent compound until an innocuous end product is produced. This process creates unique and dramatic changes in the natural geochemistry of the aquifer system. A CVOC-impacted site located at Naval Air Station North Island (NASNI) was used as a test case for this study. NASNI is an active military base located adjacent to the City of Coronado in San Diego County, California. The site, or Operable Unit 24 (OU 24), is a chlorinated solvent groundwater plume which may have originated from an acid waste pump station associated with a historic industrial waste pipeline. The purpose of this study was to evaluate the geochemical changes that occur during EISB and how they relate to the effectiveness of remediation. An evaluation of the redox conditions present in groundwater and the observed reduction in CVOC concentrations was used to evaluate the effectiveness of EISB. In addition, geochemical modeling was performed to develop an understanding of the effect of redox conditions on observed dissolved inorganic constituent concentrations due to precipitation or dissolution of minerals present in the aquifer. Based on the results of the geochemical evaluation, groundwater generally became more reducing and VOC concentrations decreased following implementation of EISB. In addition, minerals containing Fe, Mn, and SO4 were sensitive to redox transformations. Conversely, Ca, Mg, Na, and some Mn-containing minerals were not sensitive to redox conditions. Reduced minerals FeS, FeS2, and H2S have the potential to precipitate and oxidized Fe and Mn minerals have the potential to dissolve as groundwater becomes more reducing. This can create problems with groundwater treatment systems that expose groundwater to oxygen. When reduced groundwater containing high concentrations of dissolved Fe and Mn is exposed to oxygen, the Fe and Mn hydroxide minerals will precipitate and may foul remediation equipment. Additionally, redox transformations can potentially mobilize toxic metals such as arsenic, chromium, lead, and mercury through oxidation and reduction processes., San Diego State University
A geochemical reconnaissance of thermal waters along portions of the San Jacinto and San Andreas fault zones, Southern California
Twenty-three warm spring wells from six different areas were sampled along parts of the San Jacinto and San Andreas fault zones. An additional 51 well water analyses in the studied areas were obtained from other sources. The waters were analysed for 15 different elements plus Si02 to determine: 1) if near surface mixing with local cold ground water occurs, 2) reservoir temperatures, 3) estimated depth of circulation of thermal waters, 4) water-rock reactions at depth, and 5) relationships between springs. Tritium samples were taken at each of the six areas and indicate no mixing between the ascending thermal waters and cold ground waters except for Arrowhead Springs, which was found to have a 13.5% component of cold water. Surface temperatures of the warm springs and wells range from 29°C to 85°C. Estimated reservoir temperatures vary from 48°C at Ocotillo Wells to 120°C at San Bernardino. Depth of circulation in these two areas are 0.9 km and 3.3 km, respectively, with the four other areas having intermediate values. Two of the four warm springs are sodium carbonate dominated due to water-rock reactions with originally calcium carbonate ground waters. The other two warm springs are sodium sulfate dominated and appear to be oxidized from originally sodium carbonate springs. The warm wells fall into two categories: calcium bicarbonate and sodium-calcium sulfate-chloride dominated. The different chemistries can be explained on the basis of the original recharge water and various mechanical and chemical reactions., San Diego State University
A geometric approach to block monoids
The block monoid B(G), over an Abelian group G, is the set of all zero sum sequences of G. Factorization length is one of several factorization invariants that provides an algebraic framework through which the structure of block monoids is commonly studied. In this thesis, we introduce a way to study the structure of block monoids from a geometric perspective. We look at max factorization length and explore current results for B(Z4), B(Z5), and B(Z6), and present several conjectures for block monoids over larger Abelian groups., San Diego State University
A geometric model of the human aortic valve and design of closure prostheses
Includes bibliographical references (pages 71-76)., The aortic heart valve is a delicate, complex structure that resides between the left ventricle and the aorta, enabling unidirectional flow of blood. Proper function of the valve allows unobstructed flow out of the heart, and prevention of retrograde flow into the heart (regurgitation). Congestive heart failure (CHF) is a term used to describe conditions that impair the heart's ability to provide adequate blood supply to the body. Conditions affecting the left ventricle or the aortic valve may fall into this category. A left ventricular assist device (LVAD) is sometimes prescribed to patients with CHF, to supplement the blood flow that can be provided by the heart. The LVAD is a device that mechanically pumps blood from the left ventricle to the aorta, bypassing the aortic valve. The LVAD decreases left ventricular pressure, which alters the pressure gradient across the aortic valve and causes the valve to remain closed for a longer duration, or possibly for the entire cardiac cycle. As a result, the valve leaflets my fuse to one another, and modified blood flow patterns in the region may cause hemostasis in the aortic root. By analyzing values of published data describing the dimensions of aortic valve parameters, a set of dimensions is established that describes the geometry of a typical adult valve in the closed position. These parameters include valve height, radius, and angles between features. A methodology is defined for creating 3D solid models of the aortic valve, using SolidWorks parametric design software. This methodology is used to create four models of the aortic valve, the first of which is a model comprised entirely of thin surfaces. To create the second model, additional thin surfaces are added to the valve to create aortic sinuses, an important anatomical feature of the aortic root. The third model is comprised of solids, with a solidified valve body and material thickness represented in the leaflet coaptation surfaces. The fourth model is comprised of solids as well, but has a hollow valve body and defined geometry on the proximal leaflet surfaces. Calculations are performed to evaluate the dimensions of various parameters of the valve geometry, using the defining dimensions as independent variables. Both the surface models and the solid models are successfully created, with defining parameters that can be modified based on input dimensions. The calculations are used to define valve geometry that describes two modified versions of the original valve. Additional solid models are created to reflect these modified dimensions. The modified versions have values of leaflet height at the center of the valve that are 30% and 170%, respectively, of the original leaflet height. Having created these three fully defined solid models, a physical prototype of each version is manufactured using fused deposition modeling (FDM) 3D printing technology. The physical prototypes of the original valve and two modified valves are intended for use with laboratory hardware for fluid flow analysis. Such research will provide insight into the value of prosthetic implants used to modify the topography of the aortic valve in LVAD patients, thus affecting blood flow patterns. As well, the 3D solid models and surface models may be used for a variety of computational analyses to predict fluid flow conditions and structural behavior of the valve. The models are also candidates for further geometric modification, by the addition of features to have them represent valves with either structural or acquired deficiencies.
A geovisual analytic technique for exploratory analysis of online discourses
This thesis project focuses on designing and programming an implementation of a geovisual analytic technique to evaluate online participatory decision making. The 4D (spatio-temporal) geovisualization technique called a "Grapevine" was developed by researchers at University of Washington, to evaluate the quality and scale of participatory decision interactions during an online discussion about improving transportation in the central Puget Sound region. The 4D aspect of the technique derives from its representation of location (latitude, longitude), type of discourse interaction, and time of its occurrence. The theory behind the grapevine comes from two National Research Council (NRC) publications that synthesized research on how the "analytic-deliberative" process can improve decision making about risks to public health, public safety, and the environment. The grapevine technique can be used to distil and cluster specific types of on-line discourse events, rank the quality of on-line participation and represent spatial trends in on-line discourses. This work is about the automation of grapevine functionalities including robust database queries in a desktop Geographic Information System (GIS) environment based on Environmental Systems Research Institute (ESRI) ArcGIS software.
A gift shop in Gilead: Kitsch, propaganda, patriarchy
Using the fictitious society of Gilead from Margaret Atwood’s novel, A Handmaid’s Tale, as its foundation, A Gift Shop in Gilead is an investigation into creating and commodifying a visual narrative of an oppressive theocracy into kitsch souvenirs and how this process simultaneously reinforces cultural standards to those it oppresses while legitimizing, normalizing, and celebrating this ideology to tourists. This project aims to show the influence of art as both visual rhetoric and commodity as it pertains to those who produce it, as well as the implications for those who consume it., San Diego State University
A glass microfluidic platform for rare cell capturing using passive micromixing
The isolation and capture of rare cells continue to be challenging tasks for researchers. By capturing these rare cells, like cancer stem cells, researchers can further study and understand cancer progression. Micro Electro Mechanicals Systems (MEMS) provides the necessary tool to investigate this issue further. Microfluidic platforms using several techniques have demonstrated the ability to isolate and capture rare cells. In this work, we fabricate a 16-channel microfluidic device using glass substrates. 3D chevron features are incorporated into the channel design to promote micromixing. This project's innovative idea uses glass substrates to fabricate a double-layer device. The isotropic etching properties of glass allow the fabrication of channels with rounded walls, previously impossible or complicated with Polydimethylsiloxane (PDMS) devices. The rounded channel walls allow studying new geometry and aspect ratios to improve rare cell capture efficiency by increasing cell collisions with the walls. Also, one can take advantage of the borosilicate glass mechanical properties to create a more durable device with minimal channel deformation due to pressure. Finite Element Analysis is used to study the flow characteristics and optimize channel design. This research's primary outcome is developing an optimized glass micromachining protocol to fabricate microfluidic devices and produce channels with geometry and aspect ratio (width to depth) not possible with PDMS. The fabrication time decreased approximately 45%, from 370 minutes to 170 minutes. While microfluidic channels with aspect ratios of up to 8.5 were fabricated successfully. Lastly, a flow test was performed on the double-layer glass microfluidic device using a 200 μL per minute flow rate. The results accomplished throughout this thesis demonstrate the potential to improve current microfluidic devices further using glass micromachining., San Diego State University
A graph theory study of regional and network functional connectivity in autism spectrum disorders
Autism spectrum disorder (ASD) is a neurodevelopmental disorder. The inherent heterogeneity of autism presents great challenges for researchers, but evidence across neuroimaging modalities is now converging, implicating aberrant connectivity patterns involving numerous functional networks. At the same time, there is minimal agreement as to the exact patterns of aberrant connectivity in ASD, with numerous competing theories. Given the complexities and inconsistencies of the ASD literature, data-driven techniques can provide unbiased approaches to uncovering connectivity patterns. In the current study, we used graph theory to examine differences in connectivity patterns between the ASD and typical development (TD) groups using resting state functional magnetic resonance imaging (fMRI) data, which reflect fluctuations in oxygen levels in the brain as an indirect measure of neuronal activity. For the analysis, we first used graph theory to examine functional connectivity at the regional level in a large sample of low-motion resting-state fMRI scans. We then tested how within-network connectivity differed between the two groups, as well as how it changed with age in the two groups. In the second portion of the study, we used independent component analysis to define functional resting-state networks in the brain and then graph theory to examine how the networks interact. Once again, we tested for group differences in connectivity and age-related changes. Findings suggest decreased density of connectivity in the ASD group compared to the TD group, both at the regional and network levels. Within-network connectivity was significantly reduced in the ASD group for somatosensory & motor, auditory, cingulo-opercular task control, subcortical, and default mode networks. Furthermore, numerous networks in ASD showed differing age-related trajectories. Both groups exhibited a decrease in regional connectivity with age. The TD group showed the expected increase in network connectivity with age, but this trend was not present in the ASD group. These findings support the theory of reduced network integration with age in ASD.

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