Collection Description

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

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Validation of the Strategies for Weight Management Questionnaire for Overweight or Obese Adults
Includes bibliographical references (pages 57-65)., The aim of this research is to validate the Strategies for Weight Management (SWM) questionnaire. The SWM is a 35-item self-report measure that assesses the use of recommended behavioral strategies for reducing energy intake and increasing energy expenditure to promote weight management in overweight/obese adults. Exploratory (EFA) and confirmatory (CFA) factor analyses were conducted on the SWM. Baseline data were collected from 404 young adults (mean age=22±3.8 years, 70% female, 68% ethnic minority) for the EFA and 236 adults (mean age=42±11.1 years, 75% female, 84% ethnic minority) for the CFA. Both samples were involved in randomized controlled behavioral weight loss interventions aiming to improve diet and physical activity. Correlate models were conducted using linear regressions to assess associations between SWM subscale/total scores and demographics. Reliability (Cronbach's _) and concurrent, predictive, and construct validity were assessed with the young adult sample. Validity tests conducted with linear regressions examined associations between the SWM and weight management outcomes (i.e., weight and self-reported diet and physical activity) using baseline and 6-month data. Signal detection analysis was conducted to identify subgroups of overweight/obese young adults more or less likely to lose ≥5% body weight in 6 months. SWM items and subscale/total scores were predictor variables. Final subgroups were compared by demographics. EFA and CFA suggested a four-factor model: strategies categorized as targeting 1) energy intake, 2) energy expenditure, 3) self-monitoring, and 4) self-regulation. Correlate models revealed weak associations with demographics. Cronbach's _ for subscale/total scores ranged from 0.74-0.85. Subscale/total scores predicted select concurrent, predictive, and construct relationships. Signal detection identified three SWM items that best predicted weight loss success, with success ranging from 5.5%-45.8%. Subgroups did not differ by demographics. The SWM showed promising psychometric qualities in two diverse samples of overweight/obese adults. Use of the SWM may promote weight management and ultimately provide a better understanding of the recommended strategies associated with improved weight management.
Values and normativity: A study of the metaethical foundations of prescriptive ethics
Moral nihilism, the view that "nothing matters," denies the possibility of identifying an objective source of normativity because it denies the existence of moral facts or truths. Since ethics purports to guide proper human actions, the truth of nihilism would undermine this crucial function. Cognitivists, those who believe that moral facts and truths exist and humans have the capacity to recognize them and act accordingly, are united by their eschewal of nihilism but are divided as to how to justify this position. Rationalism and Naturalism are two broad metaethical views competing for this prestige. Prominent philosopher, Derek Parfit, argues in his treatise, On What Matters, that Rationalism is the only viable foundation to support Cognitivism. Rationalism holds that fundamental normative truths are irreducibly normative. This view, in other words, declares that there is deep cleavage between normative truths and natural truths—truths about what should be and truths about what is. Rationalism purports to be an objective metaethical foundation for devising a robust normative theory, but several irredeemable flaws are revealed upon closer inspection. Rationalism depends on a defective conception of objectivity because it implausibly insists in the existence of intrinsically valuable goods and corresponding intuitive abilities for their recognition. Contra Rationalism, intrinsic values and intuitive abilities are invariably subjective criteria and ipso facto cannot support Cognitivism. These failings do not apply to Naturalism, despite criticisms to the contrary. According to Naturalism, the concept of a value is not an irreducible primary; it presupposes a beneficiary that stands to gain or lose in relation to its obtainment. Values, in other words, presuppose an answer to the question: of value to whom and for what? Since life forms are the only class of entities whose existence is conditional upon the successful and recurring obtainment of values, life is the progenitor of values and source of normativity. This paper is predominantly concerned with refuting Rationalism as advocated by Derek Parfit and exhibiting the defense of my metaethical position I call Metaphysical Naturalist Cognitivism, which essentially claims that life is the one and only objective standard of normativity., San Diego State University
Variability in greenhouse gas dynamics due to spatial heterogeneity and seasonality in Alaskan Arctic coastal wetlands
The regional warming of high latitude ecosystems, such as the Arctic tundra, is occurring at an accelerated rate relative to the global average due to a considerable number of positive feedbacks. These ecosystems contain one of the largest terrestrial reservoirs of carbon and nitrogen, locked in the soil column by low temperatures and slow decomposition. However, warming temperatures are increasing emissions of primary greenhouse gases (GHG): carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from these immense Arctic reservoirs. Increased release of greenhouse gases from permafrost dominated regions is providing a strong positive feedback on climate warming. While attention to GHG dynamics in permafrost regions has increased over the past decade, understanding patterns and controls on GHG emissions due to seasonality and spatial heterogeneity are still poorly understood. This is particularly true for non-CO2 greenhouse gas fluxes CH4 and N2O which are still understudied. Here, I use a combination of data from a network of eddy covariance towers, soil carbon measurements, and chamber flux measurements on the Arctic Coastal Plain to better understand the seasonal and spatial controls on GHG emissions from the Alaskan Arctic. I show that the timing and magnitude of carbon (CO2 & CH4) fluxes can be highly variable (77-107 g C-CO2-eq m-2 year-1) based on mesoscale (<1 km) hydrological status. While fall CH4 emissions comprise up to 45% of the annual regional CH4 budget, there has been uncertainty as to whether emissions of CH4 during the fall are the product of active methanogenesis or the release of stored methane generated during the prior growing season. Here, I show that fall methane emissions (1100±50 mg C-CH4 m-2) outweigh methane storage within the soil active layer (106.8±7.9 mg C-CH4 m-2 - 35cm depth). These results indicate that the dominant source of CH4 emissions during the cold period is likely microbial activity rather than the release of stored methane. Finally, while emissions of N2O have been thought negligible in Arctic wetlands due to low nitrogen mineralization and high plant-microbe competition for inorganic nitrogen, I show that features of the landscape that are collapsing due to ice wedge and permafrost degradation are important N2O sources, as high as 38.6 mg N m-2 d-1, more than an order of magnitude higher than previously assumed. This understanding of trends, budgets, and drivers of GHG fluxes in the Arctic is intended to help increase accuracy in regional and global climate model projections., San Diego State University; University of California, Davis
Variables influencing contextualized moral reasoning
The purpose of this study was to explore cross-situational consistency in moral reasoning. Based on Kohlberg's developmental theory, which hypothesizes within-subject consistency of moral reasoning, adults' moral rationales were analyzed. The investigation centered on whether the moral reasoning utilized in response to abstract, remote, hypothetical moral dilemmas differed from the reasoning employed in more concrete situations. The design utilized paper and pencil instruments in group administered settings with 161 college students. The Ethical Reasoning Inventory and the revised Objective Assessment of Moral Development were used as the abstract and contextualized measures of moral reasoning. Respondent demographic characteristics, respondent past moral crisis experience, the format of the moral development instrument, and the contextual characteristics of the moral conflict situation were hypothesized as influencing moral reasoning. A within-subjects post-hoc analysis was undertaken utilizing an array of multivariate techniques. Discriminant function analysis was employed in building a predictive model of situationally influenced moral reasoning. Five significant findings emerged. First, a low--but significant--correlation existed between abstract and contextualized moral reasoning ability. Second, verbal ability was correlated positively with contextualized moral reasoning ability. This relationship held even when controlling for age, gender, ethnicity, marital status and past experience. Third, past moral conflict experience was inversely related to moral maturity on remote content dilemmas. Fourth, both male and female respondents were influenced by two contextual features, i.e. the gender and socioeconomic status (SES) characteristics of the moral dilemma model. Contexts involving male and female low SES models evoked less mature reasoning. Fifth, an 80% accuracy rate was obtained when using the canonical discriminant function to predict respondent level of moral maturity in contexts involving male and female low SES models., San Diego State University; Claremont Graduate School, Digitization of this archival thesis was made possible through a generous donation from Robin B. Luby.
Vascular contributions to neurocognitive impairment among older persons with HIV
HIV-associated neurocognitive impairment (NCI) is highly prevalent in the modern era of combination antiretroviral therapy, and older persons (50 years and older) are particularly vulnerable to the burden of HIV-associated NCI. In addition, cardiovascular disease is increasingly observed in HIV. Three studies were conducted to investigate the association between markers of vascular risk and NC function among persons living with HIV/AIDS. For all three studies, participants completed standardized neurobehavioral and neuromedical assessments. NC function was evaluated using a well-validated comprehensive battery. The first study evaluated the relationships among markers of vascular remodeling, arterial stiffness (measured by pulse pressure, PP), and NC function among older HIV-seropositive (HIV+; n = 72) and HIV-seronegative (n = 36) adults. A biomarker of vascular remodeling was associated with greater PP and worse NC function. PP had a quadratic relationship with NC function, such that lower and higher PP values, relative to the entire sample mean, were associated with worse NC function. These findings indicate that vascular remodeling may contribute to arterial stiffening and changes in PP, which, in turn, deleteriously affect NC function. The second study assessed the impact of disturbances in coagulation on NC function in the same cohort of older HIV+ and HIV-seronegative adults. Coagulation moderated the effect of HIV on NC function, such that greater coagulation imbalance was associated with poorer NC function among HIV+ participants. The moderating effect of coagulation on neurocognition was driven by procoagulant but not anticoagulant or fibrinolytic biomarkers. These findings indicate that procoagulation may exert a detrimental effect on NC function among older HIV+ adults. Lastly, the third study aimed to examine the association between visit-to-visit variability in blood pressure (BPV) and NC change in a well-characterized HIV+ cohort (N = 533). BPV was not significantly associated with rate of NC change; however, baseline PP was a significant predictor of rate of NC change. These findings suggest that arterial stiffness might be a crucial factor impacting NC function over time among HIV+ adults. The findings of these studies indicate that vascular remodeling, arterial stiffening, and procoagulation may contribute to poorer NC outcomes among HIV+ persons. Biomarkers of vascular processes may provide valuable information regarding the prognosis and risk stratification of HIV+ adults for NCI.
Vector Field Generator for a Direct Mapping of the First Order Poincaré Sphere
Includes bibliographical references (pages 75-76)., This thesis presents an optical system able to generate all polarization states on the zero order Poincaré sphere. An important characteristic of the zero order sphere is its spatial uniformity. This means that the polarization of the beam is uniform. This characterization can be proven using polarizers. Any change in the polarization of the beam will be consistent for all points in the beam. This is not necessarily true for all types of polarization states. There are new polarization states that are spatially variant in which the polarization is no longer uniform. The assumption that the polarization at one point in the beam is the same at all points is no longer valid. These are defined as higher order polarization states which have their own Poincaré spheres that are similar to the zero order sphere but are spatially variant. The higher order polarization states are the focus of this thesis. Maxwell's equations are shown and the solution for light is derived. From this, Jones vectors are used to describe the polarization and how they relate to the Poincaré sphere. Jones matrices are applied to the incoming polarization state to reflect the changes a waveplate causes to the system, and how to create a rotator to rotate the axis of polarization. The matrices describe an optical system consisting of a variable waveplate and a rotator created from 2 quarter waveplates and an additional variable waveplate that able to change the latitude and longitude of a polarization state on the Poincaré sphere. The system is able to achieve any coordinate on the surface of the sphere. The system is applied to the zero order Poincaré sphere and the positive and negative first order Poincaré sphere. Experimental results are presented and agree with theory.
Vegetation and fluvial geomorphology dynamics after fire in urban mediterranean riparian areas
The role of non-native riparian vegetation in urban fire regimes within Mediterranean riverine systems (Med-sys) is not well documented. A combination of satellite indices and in field surveys were used to investigate the impact of non-native), riparian, or upland vegetation on the spatial and temporal variability of fire severity and canopy loss was compared across eleven fires in southern California. Satellite-based metrics, differenced Normalized Burn Severity (dNBR) and differenced Normalized Difference Vegetation Index (dNDVI), were approximated for native and non-native vegetation for 0, 1, and 3 years after fire. Generally, the riparian class burned more severely and experienced a greater loss of green canopy than the upland land class. The presence of invasive vegetation affected the distribution of burn severity and canopy loss. On average, across both upland and riparian regions, fires with native vegetation cover burned at a higher severity and resulted in larger immediate loss of canopy than fires with non-native vegetation. The lower burn severity observed in the fires with non-native vegetation suggests a rapid regrowth of non-native grasses immediately after fire, resulting in a smaller measured canopy loss relative to native vegetation. A case study of the Del Cerro fire (San Diego, California) was used to compare observations of native and non-native vegetation and fluvial morphology in the upland and riparian regions. Field observations noted rapidly re-sprouting invasive grass species such as Arundo donax (Giant Reed). While, satellite-based metrics underestimated the initial green canopy loss after urban fires as did volumetric data derived from three-dimensional terrestrial laser scanning data (TLS). Fire damaged trees and chaparral and decomposition of burned branches contributed of vegetation volume throughout the first six months following the fire, exceeding the combined density of resprouting vegetation. The presence of Arundo donax significantly increased channel instability in the riparian region and encouraged the deposition of sediments in the floodplain (accretion). This geomorphological mechanism can promote riparian desiccation and fire risk. Ultimately, this work builds considerably upon our current knowledge of wildfire and recovery processes and informs understanding of the post fire mechanisms and anthropogenic feedbacks unique to urban Med-sys., San Diego State University