Physical Sciences and Mathematics Commons^™

Beyond Genetics: Addressing Activity In Microbial Ecology, Scott Christopher Thomas

UNLV Theses, Dissertations, Professional Papers, and Capstones

The field of microbial ecology is on the cusp of another revolution, one that uses synergy to address the limitations of previous studies. My dissertation is representative of the new era of research to come, through combining the latest technological advances with established classical methods to provide a more complete understanding of microbial ecosystems. In my first study, I evaluate the conservation of central carbon metabolic pathways and activity along a temperature and diversity gradient (60-95 ℃) through the use of 16S rRNA gene amplicon data, metagenome sequencing, and position-specific 13C-labeled metabolite probing. In my second study, I provide the …

Effects Of Disturbance And Restoration Treatment On Fertile Islands In Lake Mead National Recreation Area, Camille Traylor

UNLV Theses, Dissertations, Professional Papers, and Capstones

Disturbances by humans are one of the main drivers of change in contemporary desert ecosystems. Restoration treatments such as topsoil application and outplanting can be implemented in response to disturbances in order to maintain soil stability and a diverse plant community. Fertile islands - nutrient enriched areas beneath perennial shrubs - are fundamental features of deserts that can facilitate annual plant growth. A major uncertainty in desert ecology is how much time is required for fertile islands and nurse plant effects (the facilitation of one plant by another) to develop below maturing perennial plants. By studying naturally recruited perennial plants …

The Affective Perceptual Model: Enhancing Communication Quality For Persons With Pimd, Jadin Tredup

UNLV Theses, Dissertations, Professional Papers, and Capstones

Methods for prolonged compassionate care for persons with Profound Intellectual and Multiple Disabilities (PIMD) require a rotating cast of import people in the subjects life in order to facilitate interaction with the external environment. As subjects continue to age, dependency on these people increases with complexity of communications while the quality of communication decreases. It is theorized that a machine learning (ML) system could replicate the attuning process and replace these people to promote independence. This thesis extends this idea to develop a conceptual and formal model and system prototype.

The main contributions of this thesis are: (1) proposal of …

A Monolithic Arbitrary Lagrangian-Eulerian Finite Element Method For An Unsteady Stokes/Parabolic Interface Problem, Ian Kesler

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, a non-conservative arbitrary Lagrangian-Eulerian (ALE) method is developed

and analyzed for a type of linearized Fluid-Structure Interaction (FSI) problem in a

time dependent domain with a moving interface - an unsteady Stokes/parabolic interface

problem with jump coefficients. The corresponding mixed finite element approximation is

analyzed for both semi- and full discretization based upon the so-called non-conservative

ALE scheme. The stability and optimal convergence properties in the energy norm are

obtained for both schemes.

Early Contractional History Of The Funeral Mountains And Its Influence On The Formation Of The Funeral Mountains Metamorphic Core Complex, Death Valley, Ca, Taylor Douglas Craig

UNLV Theses, Dissertations, Professional Papers, and Capstones

Zones of localized crustal thickening in orogenic belts commonly host low-angle normal faults, which have been controversial since their recognition. The metamorphic core complexes of the Sevier hinterland are localized within a belt that is attributed with the highest degrees of crustal thickening during Sevier orogenesis. This association of deep-rooted detachment faulting and early contractional deformation indicates an important link between the two processes, however repeated tectonic episodes often overprint and obscure the earlier fabrics, making this link difficult to study. The Funeral Mountains metamorphic core complex, located in Death Valley, CA, has a complex history of protracted SE-contraction and …

Assessing Simulated Transmissivity In Numerical Flow Models Of Complex Hydrogeology, Afan Tarar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accurately extracting a meaningful transmissivity, a target value within one order of magnitude of field estimates, in numerical models poses a significant challenge when modeling complex groundwater systems. Aquifer transmissivity is directly proportional to the aquifer thickness and the estimated aquifer hydraulic conductivity. In complex geologic conditions (especially in fractured systems) with multiple heterogeneous and anisotropic hydrogeologic units, transmissivity can vary over several orders of magnitude.

To extract a meaningful value of transmissivity from a numerical model, a simple five-layer MODFLOW model was constructed. Each layer in the model was assigned a fixed hydraulic conductivity and thickness. The model simulates …

Preparation And Evaluation Of Uranium Alloys Based On Burnup, Andrew Jonathan Swift

UNLV Theses, Dissertations, Professional Papers, and Capstones

Next generation fast reactor designs utilizing metallic fuel are being developed as an alternative fuel cycle option in an effort to reduce carbon emissions. Historically, oxide fuels have been the industry standard, but interest in metallic fuel systems has grown considerably due to their thermal conductivity, fissile atom density, inherent safety, and ability to reach progressively higher burnups. Chemical complexity of metallic fuel systems increase as a function of burnup from fission product ingrowth and associated fuel cladding chemical interactions (FCCI) brought on by elemental redistribution and phase formation. To date, the most extensive operational study for metallic fuel was …

Long-Term Monitoring Of Rare Gypsum Communities In The Eastern Mojave Desert: A Study In Science And Art, Tiffany Jane-Marie Pereira

UNLV Theses, Dissertations, Professional Papers, and Capstones

For land managers, reliable estimates of soil seed banks, and more specifically, change in seed banks over time, provide insight into the restoration and regeneration potential of the landscape, site history and disturbance mapping, and, invasive and rare plant management. To understand the intricacies of desert soil seed banks in relation to aboveground vegetation change, my research evaluated long-term change in soil seed banks, fertile islands, and plant communities of conservation-priority gypsum rare plant habitat of the eastern Mojave Desert. Research found significant spatial and temporal differences in seed bank composition and density over an 11-year period; however, the gypsum …

Contributions To Mcmc Methods In Constrained Domains With Applications To Neuroimaging, Sharang Chaudhry

UNLV Theses, Dissertations, Professional Papers, and Capstones

Markov chain Monte Carlo (MCMC) methods form a rich class of computational techniques that help its user ascertain samples from target distributions when direct sampling is not possible or when their closed forms are intractable. Over the years, MCMC methods have been used in innumerable situations due to their flexibility and generalizability, even in situations involving nonlinear and/or highly parametrized models. In this dissertation, two major works relating to MCMC methods are presented.

The first involves the development of a method to identify the number and directions of nerve fibers using diffusion-weighted MRI measurements. For this, the biological problem is …

Petrogenesis Of The El Rechuelos Rhyolite, Jemez Mountains Volcanic Field, New Mexico, Usa, Kelsy Jo Konkright

UNLV Theses, Dissertations, Professional Papers, and Capstones

The El Rechuelos Rhyolite represents volcanic activity preceding the multiple caldera collapse events of the Jemez Mountains volcanic field (JMVF) in northern New Mexico. This study focuses on seven rhyolitic units clustered north of the Valles caldera. These units have been studied in order to interpret their relationships to one another and the eruptive history of the JMVF. Additionally, this study adds to the research on the relationships between effusive and explosive rhyolitic volcanism, and understanding how caldera-forming eruptions develop from silicic systems.

Limited previous research includes K/Ar dates and a few inconsistent 40Ar/39Ar dates, in addition to whole rock …

Health Disparities Among Sexual And Gender Minorities, Jennifer Keeley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Decades of research has shown that sexual and gender minorities (SGMs) experience adverse health and mental health outcomes to a greater extent than their heterosexual peers. The need to better understand and eliminate health disparities in the SGM population was recognized by the National Institute on Minority Health and Health Disparities (NIMHD) at NIH. The Secretary of Health at the Department of Health and Human Services approved the designation of the SGM population as a health disparities population in 2016 and called for SGM studies to examine the health needs of the SGM population across SGM subgroups via large representative …