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A Comprehensive Analysis of Station Performance for the Nevada Seismological Laboratory Network
Get PDFEarthquake hazards in Nevada are comparable to much of California, making instrumental studies of earthquakes in densely populated regions crucial for hazard mitigation and response. The Nevada Seismological Laboratory (NSL)is responsible for monitoring seismic activity in this area, and over time has installed a robust seismic network to accomplish this goal. This study explores the seismic stations managed by the NSL with the aim of integrating sophisticated systems like ShakeAlert into Nevada's infrastructure to enhance community safety in the face of seismic hazards. A comprehensive analysis of seismic station noise is conducted for the future development of an effective Earthquake Early Warning (EEW) system. Understanding noise characteristics is crucial for assessing network reliability and robustness for EEW applications, with identified noise sources being essential for accurate seismic event detection. The study reveals consistency in noise levels among the majority of stations, indicating stable performance, while identifying several inconsistencies among individual stations that warrant further investigation. Noise analysis provides insights into station performance and areas for improvement. Analyzing seismic stations with varying instrument responses underscores the importance of determining the correct response model for data calibration and accurate signal processing. Overall, this study contributes to the groundwork for implementing an effective EEW system in Nevada, fortifying the NSL's capacity to support EEW initiatives and enhancing community resilience to seismic hazards
Modeling the Future Distribution of Rubus chamaemorus (cloudberry) in Alaska
Get PDFRubus chamaemorus, cloudberry, is a species of wild berry with high cultural and nutritional value to Indigenous, subsistence-based communities in Alaska. Motivated by existing research suggesting subsistence berries could be vulnerable to climate change impacts, Maximum Entropy (MaxEnt) niche modeling was used to understand historical and projected future distributions of cloudberry habitat suitability in five distinct regions of Alaska: Interior, North Slope, Southcentral, West Coast, and Southeast. Leveraging climatological data and other environmental variables, five climate models from CMIP5 (CCSM4, GFDL-CM3, GISS-ER-2, IPSL-CM5A-LR, and MRI-CGCM3) and two Representative Concentration Pathways (RCP 4.5 and RCP 8.5) were applied to create projected MaxEnt distribution models for the period 2070-2099. Findings reveal significant regional variability in potential habitat suitability responses to projected climate data in most regions and widespread habitat contraction in the North Slope region. Areas with projected maintenance and expansion of suitable habitat suggest that cloudberries may be resilient to climate change or even find new growth opportunities in certain regions. Unexpected projected contraction in the North Slope should be interpreted with caution, due to various uncertainties including limited sampling data and novel climate responses. With study limitations in mind, insights were gained into a range of potential future outcomes for cloudberry habitat suitability across Alaska
Comparing Potential Fields and Velocity Obstacles for Rules of the Road Compliant Ship Driving
Get PDFWe propose two algorithms for nautical rules of the road compliant ship driving and collision avoidance: one that uses genetic algorithm trained potential fields, and one that determines a new trajectory from velocity obstacles and the closest point of approach. Prior work has used a variety of methods for ship driving, including genetic algorithms and velocity obstacles. However, the usage of potential fields in ship driving is unexplored and many ship driving algorithms are not tested on environments with multiple vessels. Therefore, we aim to provide new methods of ship driving and show that these methods are viable. We develop a 3D simulation environment that is able to more quickly process through situations by disabling the graphics component. We use this simulation environment to train our Genetic Algorithm Tuned Potential Fields for Ship Driving (GAPFS). Our potential fields use a distinct algorithm that is based on the angles of the vessels, and we use a fitness function that is based on a programmer defined path. We then develop the Velocity Obstacle COLREGs Colision Avoidance Algorithm (VOCCAA) to handle scenarios with multiple entities. This algorithm uses velocity obstacles to determine whether or not two ships will collide with each other, as well as to provide trajectories that do not lead to further risk-of-collision situations. Experimental results using the simulation environment show that both methods have potential to be viable approaches to ship driving. GAPFS is able to closely follow the specified paths for both vessels in the situation, despite the paths requiring different behavior. VOCCAA is able to plan new trajectories for multiple vessels in ambiguous situations. A comparison between the two algorithms shows that VOCCAA can handle random situations better than the potential fields method
The Effect of Prescribed Burning on Soil Microbial Communities, Nutrients, and Carbon Dioxide Fluxes Under and Between Sagebrush Canopies in the Semi-Arid Rangelands of Northern Nevada
No full textWildfire and the invasion of cheatgrass (Bromus tectorum L.) are some of the greatest challenges in western U.S. rangelands. The spread of wildfire has been shown to cause immediate and long-term changes to soil microbial communities, nutrient dynamics, and carbon dioxide (CO2) fluxes. These changes can have direct and indirect effects on soil biochemistry and respiration. The effects of fire on soil largely depend on time and seasonality, frequency, severity, and management practices pre-and-post burning. The cultivation of squirreltail (Elymus elymoides (Raf. Swezey), a desirable perennial plant species, can be used to curb the spread of cheatgrass. A prescribed burn was conducted at the University of Nevada Reno Experimental Station Gund Ranch. A greenhouse experiment was also conducted using burned and unburned soils collected from the experimental site to monitor cheatgrass invasion, the cultivation of cheatgrass, and squirreltail. We hypothesized that 1) the burning of vegetation in a sagebrush community leads to both short- and long-term changes in soil plant-essential nutrients and microbial communities compared to soils of unburned vegetation, 2) soil nutrient and microbial populations continue to differ between sagebrush canopies and interspaces; and 3) the burning of sagebrush vegetation has an impact on both short- and long-term soil CO2 fluxes. The main objectives of this study were: 1) to investigate the short- and long-term effects of fire on soil nutrient dynamics and microbial relative abundance and diversity within and between sagebrush canopies; and 2) to assess the short- and long-term effects of burning sagebrush vegetation on soil CO2 flux. Our hypotheses for the greenhouse experiment were that the cultivation of squirreltail would inhibit cheatgrass growth and invasion, and that soils taken from under shrub canopies would have greater soil nutrients than soils taken from between shrubs interspaces. Overall, the aims of this study were: 1) to assess the effects of fire on soil nutrients and microbial populations between and under shrub canopies, and 2) to monitor the effects of cultivating squirreltail on subsequent cheatgrass invasion. For the field experiment, a randomized complete block design was used to assign burn and control treatments to plots at two sites. Soil samples were collected at depths from 0 5 cm from October 2018 to October 2020 at site one, and from October 2019 to October 2020 at site two. Soil samples were collected in each plot five days before burning and 9, 23, 176, 204, 259, 286, 355, 382, 547, 582, 631, 656, and 698 days after burning (DAB). At the second site, soil samples were collected five days before burning and 9, 23, 176, 204, 259, 286, and 355 DAB. Collected soil samples were analyzed for soil macro and micronutrient compositions and soil microbial (bacteria and fungi) relative abundances and diversities. Soil moisture was measured during soil sampling. Soil CO2 gas samples were collected once every month for two years at site one and for one year at site two. Gas samples were collected at three different times, time zero (T0), time ten (T10), and time twenty (T20). Soil temperature and moisture were collected about 10 minutes into gas sampling. Data were analyzed using a two-way analysis of variance (ANOVA) for four treatments: 1) Control (unburned) under shrub (CT-USB); 2) Control interspace (CT-ISP); 3) Burned, interspace (BRN-ISP); and 4) Burned, under shrub (BRN-USB), and time in site one (5 days before burning and 9 to 698 DAB) and time in site two (5 days before burning and 9 to 355 DAB). Repeated measures analysis was also made to assess the effect of time on nutrients, microbial communities, and CO2 efflux. Separate ANOVAs were calculated for: 1) soil nutrients (NH4+, NO3-, HCO3-P, total nitrogen (TN), total carbon (TC), pH, Cu+2, Fe+2, Mn+2, and Zn+2); 2) bacteria (16S) and fungi (ITS) relative abundance and diversity; and 3) CO2 fluxes. For the greenhouse experiment, similar soil nutrient variables were measured, plus plant growth measurements of invasive cheatgrass, cultivated cheatgrass and squirreltail in pots containing soil taken before and after burning from the field sites, including soil taken between and under shrub canopies. Differences among means were evaluated using Tukey’s honestly significant difference (HSD) test with a 95% significance level. Our study revealed consistent and significant increases in several soil nutrients beneath sagebrush canopies immediately after burning, with some effects lasting up to nearly two years. However, certain nutrients such as NO3-, Cu2+, and Zn2+ only slightly changed after burning. Among microbial communities, we observed a decrease in both bacteria and fungi relative abundance, particularly in burned soils under canopies, immediately after burning. We also observed a consistent increase in microbial abundances starting 176 DAB, which continued into the second year. These results agree with previous studies indicating that fire results in an immediate reduction in soil microbes in semi-arid ecosystems, especially in soils under shrub canopies. Our results demonstrated that fire has a direct effect on soil CO2 respiration in cold desert sagebrush ecosystems in both the short and long term. Although burning did not immediately lead to a rise in soil CO2 fluxes, it did bring about significant changes to soil respiration over time. This was primarily observed through increased CO2 emissions, especially during the warmer seasons. In the greenhouse experiment, our results showed that the seeding of native perennial grass like squirreltail can be effectively used to manage cheatgrass invasion, which could potentially be used to reduce the frequency and spread of wildfire in northern Nevada rangelands and forests
Ultracold Molecular Structure and Collisions
No full textUltracold molecules are instrumental in many fields of physics, such as high-resolution spectroscopy, quantum computation, and cold controlled chemistry. In this dissertation, we discuss the structure and collisions of ultracold molecules in the presence of external magnetic fields. We explore these topics in four main projects. First, we study ultracold chemical reactions of triplet-state NaLi ( a 3 Σ + ) molecules with Na atoms in the presence of an external magnetic field. We observe that by tuning the magnetic field to a Feshbach resonance or by starting the reactants in their fully spin-polarized hyperfine and rovibrational states, the NaLi ( a 3 Σ + )+Na→Na 2 +Li reaction can be suppressed by several orders of magnitude. Second, we propose a mechanism to tune the electric dipole moments and long-range dipolar interactions of polar alkali-dimer molecules (such as KRb) with external magnetic fields. We find that this tunability is possible due to the quantum ergodicity of molecular eigenstates at low magnetic fields and the avoided crossings caused by the nuclear-electric quadrupole interaction. Third, we use a rigorous coupled-channel method to examine quantum nuclear spin dynamics in cold collisions between 13 C 16 O molecules and He atoms. We found that the transition rates depend on the initial and final state's projections of rotational and nuclear spin angular momenta ( M N and M I ). We observed that certain transition rates are dependent on the magnetic field, and explained this dependence using the first Born approximation. We utilize the transition rates we have calculated to find the nuclear spin relaxation rate of 13 C 16 O in a helium buffer gas. We find the relaxation rates are highly dependent on temperature. Finally, we demonstrate that cold collisions between 13 C 16 O molecules and He atoms can be used, in combination with microwave pumping, to produce cold spin-polarized molecules with high efficiency (≥ 95%) at 1 K. This is accomplished by pumping the molecules to the first rotational excited state and allowing spin and rotational state-changing collisions to occur, which populate a single final spin state
Applying U-Th Disequilibrium to Dating Siliceous Sinter
No full textContinental hydrothermal systems are critical avenues for the crustal transport of heat and mass captured for geothermal energy and mineral exploration. Thus, understanding their temporal evolution and longevity is important for resource characterization. In particular, high temperature reservoirs (> 170°C), which are commonly marked at the surface by deposits of microlaminated siliceous sinter, have the potential to trace hydrothermal histories. Previous attempts to use radiocarbon (14C) dating in active modern systems have encountered problems matching ages with stratigraphy, possibly due to contamination with old carbon leading to older apparent ages. Geothermal reservoirs are often positioned within uranium (U)-rich silicic volcanic rock where subsurface fluid-rock interactions extract U into hydrothermal fluids. As U is precipitated in the surface sinter deposit, assuming closed-system behavior, it begins to produce Th as an intermediate daughter product within the U-Th-Pb decay chain. If this assumption is correct, the U-Th disequilibrium geochronologic method becomes an additional dating option. While U-Th dating has been broadly utilized in carbonates, a systematic methodology has not been established for siliceous sinter deposits. As U-Th ages require only milligrams of material, this would potentially allow detailed chronologies of microlaminated material. For this work, we collected samples from El Tatio geyser field in the altiplano of northern Chile, the largest geothermal system in the Andes. Radiocarbon dating has been conducted at El Tatio and its arid climate offers exceptional preservation of deposits. Our resulting U-Th ages, along with the water and deposit chemistry, suggest trends of U and Th accumulation along the sinter apron. While distal facies containing the highest U concentrations (> 50 μg/g) show the least effect from detrital Th, they can display suspected open-system behavior. In contrast, more medial facies, where bacterial mats and other porous textures are commonly concentrated, have only trace amounts of U (< 0.1 μg/g), which leads to unreliable or geologically improbable ages. More proximal facies tend to date most consistently, with repeat age results on one sample even producing a statistically significant isochron. By comparing existing 14C ages with U-Th results, El Tatio serves as an independent constraint, with U-Th ages trending younger than the 14C ages, possibly supporting the presence of an old carbon influence, and pushing forward the late Pleistocene onset of geothermal activity at El Tatio by more than 10 ka
The Sound of Struggle: A Study and Comparison of Expressive Musical Features From Works by "Dweller" Composers (1933 - 1956)
No full textIn this document, I discuss specific musical features used for representations of struggle in tonal symphonic works from a selection of what I term "Dweller" composers (a category of composers defined by their life struggles and inability to move beyond or overcome them, getting stuck to "dwell" in the aftermath of the events surrounding WWII as it affected them) from different Nazi- and Communist-occupied territories in Europe and the Soviet Union. "Dweller" composers were in similar traumatic situations during the Third Reich until just after the death of Joseph Stalin, between 1933 and 1956, and evidence exists of struggle in their lives that is present in their music. I propose that both the inner thought and feeling processes (mental and emotional) and the corporeal processes (physiological and psychophysiological) respond to these features of tension found within the pieces in my study, showing a connection to the composer's expressive compositional plan and theorized personal state based on their life's experiences at the time surrounding the writing of their piece. I achieve this by noting measurements of both basic types of bodily responses to tension that are related to the musical features that would induce these kinds of responses. I find and assess those features in the scores and draw connections and comparisons between them, showing the devices are present in the sound worlds of these scores and that they are justifiably prominent and translatable as a sound of struggle
Informing Code-Compliant Site-Specific Infrastructure Seismic Evaluations With Physics-Based Simulated Ground Motions
No full textSite-specific code-compliant approaches for seismic design require the use of a suite of ground motions that are selected and scaled to a target spectrum for performing nonlinear time-history analyses. Suitable sets of ground-motion records shall be selected by appropriately considering the earthquake parameters controlling the hazard at the site, including magnitude, fault distance, tectonic regime, and impulsive character. When tasked with the design at sites residing in the vicinity of a major active fault with site conditions not well represented in the existing catalogs of records, engineers face the challenge of not having a sufficient number of motions. This has led design codes, including ASCE/SEI 7, to contemplate the possibility of supplementing the existing database of records with simulated ground motions. Physics-based ground-motion simulations that incorporate the characteristics of fault rupture, geological structure, and topography are therefore becoming a fundamental resource to support structural design and advance understanding of seismic risk. However, technical guidance on their correct use in engineering applications is yet to be defined. This research provides the technical basis to inform the utilization of simulated motions in code-compliant structural design procedures, with a focus on two aspects: the capability of simulations to enable 'true' site-specific structural assessments as compared to approaches relying on catalogs of historical records, and the implications of different methods for modeling soft sediments on the predicted structural responses (simulation-based vs semi-empirical). Results show that utilizing site-specific simulated ground motions that incorporate path, fault geometry, and site-condition effects as opposed to historical records in code-compliant approaches may lead to differences in the structural demands above a factor of 1.5. Such differences are highly spatially variable and difficult to predict. It is also demonstrated that the utilization of hybrid methods combining simulations and empirical factors may lead to significant misestimates of structural responses, requiring the implementation of processing methods specific to the geological characteristics of the domain of interest. Finally, evidence from these analyses is collectively utilized to develop a method for the selection of simulated motions targeting component-specific spectral amplitudes and variability at the site of interest. The analyses and findings of this work are demonstrated utilizing two and three-dimensional archetypal reinforced concrete buildings of different heights
ACT for Patient Care: Effects of Psychological Flexibility and Implicit Bias on Medical Student Clinical Engagement and Academic Performance
Get PDFMedical schools are required to teach burnout management, implicit bias management, and patient-centered care (PCC). Acceptance and Commitment Training (ACT) is an empirical approach to increase psychological flexibility (PF). Increases in PF have been correlated with reductions in burnout, improvements in managing biases, and improvements in academic performance. However, less is known about relationships between ACT, PF, implicit bias, PCC, and academic performance. The purpose of this study was to examine relationships between these variables with two cohorts of medical students. Cohort One (n = 43) were exposed to ACT one time and Cohort Two (n = 48) were exposed to ACT twice. All participated in an Objective Structured Clinical Exam (OSCE) with a Standardized Patient (SP) during their third-year OB/GYN clerkship rotation and completed standardized medical knowledge competency exams. Independent samples t-tests between cohorts were conducted as well as multiple linear regressions. Results found Cohort Two (those with more ACT exposure) significantly cut-off the SP at a lower frequency than Cohort One. Participants with more clinical experience had higher performance scores for clinical engagement, asked less questions, and had less echoics. Positive implicit weight bias predicted a higher rate of echoics while implicit biases related to less burnout predicted a lower rate of echoics. Less PF was correlated with lower standardized exam scores. ACT and objective behavioral measurement may be promising technologies for medical educators to incorporate for teaching burnout management, implicit bias management, PCC skills, and ways to improve academic performance
Seeking a Safe Space: Violence, Bureaucracy, and Citizenship in the Lives of Migrants in the United States
No full textWomen are more susceptible to intimate partner violence, with migrant women facing unique challenges not encountered by citizens. Gender, combined with exposure to violence and lack of legal status, amplifies migrant women's vulnerability, subjecting them to heightened risks of exploitation, abuse, and discrimination. This dissertation is based on 18 months of fieldwork at a non-profit organization providing domestic violence and sexual assault advocacy alongside immigration legal services, a place I call Safe Space. I argue that despite the commitment and efforts demonstrated by both Safe Space staff and female migrants, the immigration programs and policies designed to support these women do not entirely change their experience of poverty, inequality, and violence. I have structured the body of this dissertation as three stand-alone journal articles, each employing a distinct theoretical lens of anthropological scholarship�"violence, bureaucracy, and citizenship�"to analyze migrants' interactions with state power, focusing on processes associated with identity and classification. The stories of migrants in these articles illustrate how various forms of violence, including direct, structural, and legal, are more than just personal trajectories but also directly connect to broader sociopolitical structures that shape individuals' lives. I recognize the U.S. immigration system as a bureaucracy that categorizes identities, frames experiences of violence, and controls through laws and legal statutes. I argue that, although this system ostensibly operates on principles of compassion and benevolence towards migrants, it often prioritizes "national security," immigration control, and an anti-immigrant political agenda. Finally, despite the state's considerable power over migrants as they navigate U.S. policies and systems, my observations reveal multiple instances when both Safe Space staff and the migrant women they assist actively resist restrictive categories and labels. Ultimately, my research calls for reconsidering and restructuring government policies and practices to better support migrants in the United States