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Closure and Post-Closure Case Study: San Manuel Heap Leach Facility, Arizona, USA
No full textThis paper was presented at the Heap Leach Solutions Conference, October 19-21, 2025, Sparks, Nevada.This paper presents a case study of the active closure and post-closure monitoring period for the San Manuel Heap Leach Facility (HLF) at the BHP San Manuel copper mine in Pinal County, Arizona, USA. Prior to closure, this HLF contained approximately 90 million tons of oxide ore and covered a 237-acre HDPE-lined footprint adjacent to the northeastern extent of the open pit and in-situ recovery wellfield. Operations at the HLF started in 1985 and ended in 2002. With formal suspension of mining operations at the San Manuel Mine Site in June 1999, BHP started the formal process of closure of the mine site and HLF. Site-specific challenges to closure of this copper HLF included short-term management of the acidic solution inventory circulating through the HLF, design of a regrade surface that achieves physical mass and erosional stability, installation of a surface water control system to contain contact water, and long-term management of residual draindown from the HLF. In 2004, the project received owner funding to commence detailed engineering and construction for permanent closure. Final closure of the HLF included expansion of the HDPE-lined footprint to accommodate the proposed regrade design, management of residual solution drain down, incorporation of landform elements and selection of a final cover system. During the active closure period, the original cover system design failed to perform as designed and the project team re-designed the system prior to completion of construction activities in 2008. BHP completed construction activities in 2008. Post-closure monitoring and inspection results include cover stability, recording long-term draindown rates, stormwater runoff volumes and maintenance activity. The long-term erosional performance of the final regrade and rock armor cover system informs future engineering trade-off studies for alternative cover systems at other sites
Interactions Between Crumples in Thin Sheets
No full textUnderstanding the deformation of thin bodies is essential in various fields, including engineering and materials science. Buckling is a form of deformation that occurs when a body is subjected to mechanical stress. A key aspect in the buckling of 2-D structures is the emergence of localized, crescent-shaped features, which play a crucial role in their behavior. However, the interactions between these features, referred to here as “crumples”, remain poorly understood. Crumples are connected by ridges and valleys, both of which exhibit considerable bending and stretching energies. Their interactions appear to be a fundamental element in many buckling scenarios. This study examines the buckling behavior of thin elastic sheets subjected to shear-induced lateral displacement of one boundary, focusing on the interaction between crumples and their role in forming two types of bound structures, which we refer to as O-valleys and S-ridges. An experimental setup was designed to measure the force exerted on a sheet as it goes through stable buckled states, as well as the force required to unbind and bind O-valleys and S-ridges. Results show that O-valleys exhibit a fold bifurcation-like behavior, with S-ridges displaying similar interactions, both characterized by crumple repulsion and attraction. Future work exploring the stretching and bending energy distributions along these structures could provide predictive models for crumple dynamics, advancing the understanding of buckling mechanics
PRESERVING THE PAST: EVALUATING EROSION RISKS TO ARCHAEOLOGICAL SITES ON SANTA ROSA ISLAND, CALIFORNIA
No full textThis thesis evaluates erosion risk to archaeological sites on Santa Rosa Island (SRI), California, using the Revised Universal Soil Loss Equation (RUSLE) implemented within the Google Earth Engine (GEE) platform. A total of 903 known archaeological site locations were compared to model outputs based on five environmental variables: rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), vegetation cover (C), and land use (P). These variables were mapped across the island and analyzed to identify areas of high erosion potential.Results show that the highest erosion values occur in the island’s northwest and northeast quadrants, particularly in steep and sparsely vegetated areas such as Arlington, Tecolote, and Cherry canyons. Archaeological sites in these areas exhibit higher model-derived risk scores than sites in other regions. Although RUSLE does not simulate coastal processes such as wave action or storm surge, some overlap is observed between areas of high terrain-based erosion risk and previously documented coastal site vulnerability zones. This may be due to the influence of slope steepness on both terrestrial and shoreline erosion.
The model does not account for short-term erosion events, marine processes, or gully formation, and assumes that input variables are independent. These limitations suggest that additional data sources and field-based validation are necessary to improve future risk assessments. This study supports the use of remote sensing and spatial modeling to identify areas where archaeological resources may be at greater risk of degradation and offers a baseline for future monitoring and management planning
Deficits in Visual-Motor Integration in Mice Reared Germ-free are Compensated for by Environmental Exposure and Experience
No full textThe superior colliculus (SC) of mammals controls fundamental aspects of visual-spatial orienting behavior, attentional control and computing the emotional valence of visual stimuli. Accumulating and recent evidence suggests a key role for early host-microbiome interactions and microglia activity towards shaping midbrain circuitry homologous to the SC in several aquatic species during development, namely tadpoles and larval zebrafish. However, how and whether microbiome manipulation and/or immune cell changes early in development influences natural SC-dependent visual behaviors and how that impacts the structure of mammalian SC was unknown. We examined natural prey capture behavior in mice raised germ free and analyzed cellular structures in the SC as well as visual cortex. Visual areas are subject to well described sensory experience-dependent plasticity during development and are linked to visual prey capture performance in mice. We found specific visual-motor integration deficits in mice reared germ-free that were partially compensated for by prey capture experience as adults. Changes in neuron number, microglia density and inhibitory tone were also found specifically in the SC relative to the visual cortex of germ-free mice with prey capture experience. This establishes a link between microbiome and SC development that impacts an adaptive visual behavior and revealed that predatory hunting allows animals to compensate for developmental deficits in visual-motor behavior induced by microorganism deprivation
Forecasting Plume-Dominated Wildfires: Environmental Ingredients Governing Depth of Pyroconvection
No full textPlume-dominated wildfires pose a major challenge to fire suppression efforts in preserving life and property, especially in the western United States. The pinnacle of pyroconvection, pyrocumulonimbus (PyroCb), can intensify wildfire behavior by inducing strong inflow and outflow winds, which often leads to rapid fire spread and long range spotting. PyroCb is capable of producing lightning and tornadoes, which makes the wildfire even more dangerous and difficult to control under these extreme circumstances. This problem can be further exacerbated by the straining of resources during an active fire season when allocating assets efficiently is critical in mitigating property loss and casualties. Fire weather forecasters attempt to predict and disseminate the potential of deep, vigorous pyroconvection to key fire management partners to assist in resource allocation and tactical planning to successfully combat intense wildfires. Techniques similar to dry thunderstorm forecasting and the use of the Haines Index are often employed to predict the atmosphere’s propensity to support plume-dominated wildfires. However, these techniques are not without their limitations and may result in under/over forecasting of impactful pyroconvection when employed. To address these shortcomings, the parcel-based “Blow-Up” model and the Pyrocumulonimbus Firepower Threshold (PFT) have been developed to assess the potential for sudden, large vertical plume growth and formation of pyroCb, respectively. Both of these models, along with the Haines Index and Hot-Dry-Windy Index, are evaluated in their ability to predict deep pyroconvection. The goal of this thesis is to improve short and near term forecasting capabilities of plume-dominated wildfires by identifying environmental discriminators and exploring the versatility of the PFT when juxtaposed with plume depth observations and Fire Radiative Power (FRPx10) data from the 2020 Creek and Bear fires. The former analysis is intended to help forecasters predict plume-dominated wildfires in the short term (24-48 hours lead time) by refining an ingredients-based forecast approach while the latter assists with near-term (up to ~6 hours lead time) forecasting precision should the PFT be deemed viable in an operational setting. Twenty wildfires in the western United States that occurred between 2018 and 2022 are investigated in this study and are selected to represent a diversity in cases with respect to location and timing, background environment, and magnitude of plume depth. The study proves the Haines Index to be a poor predictor of deep pyroconvection, distinguishes favorable environmental ingredients, and highlights the usefulness and limitations of the PFT model when coupled with FRPx10 and plume observations
Deep Neural Network-Based Simulations for Predicting, Controlling, and Characterizing BOLD fMRI Responses
No full textThrough the work presented in this dissertation, I explore how deep neural networks (DNNs) can be used to simulate, modulate, and characterize BOLD fMRI responses. In my first set of experiments, I developed a set of techniques that transform pretrained DNNs into predictive models capable of simulating BOLD responses to diverse visual stimuli. Comparisons of these simulated responses to real BOLD data show that this method accurately predicts responses in many visual cortical areas. I tested the validity of simulated responses on both naturalistic and highly controlled stimulus sets, showing that simulated data can be used to characterize real selectivity in the brain. In my second set of experiments, I explored how a DNN-based visualization technique called activation maximization can be applied to these simulation models to produce images optimized for specific cortical regions. Analysis of real BOLD responses to these images shows robust modulation of BOLD responses in targeted regions, both within and across participants. I then attempted to push these techniques to their limits, revealing both strengths and challenges of this approach. Finally, in a third set of experiments, I applied my DNN-based simulation techniques to investigate selectivity to naturalistic egomotion in scene-selective cortical areas. Analyses of simulated responses to naturalistic and hand-crafted video stimuli highlight key differences in selectivity between these regions, contributing to our understanding of their distinct functional roles. Taken together, these experiments demonstrate both the utility—and limitations—of DNN-based simulations of BOLD responses. This work serves as an important advancement of the intersection between computational neuroscience and artificial intelligence
Investigation of Gibberellic Acid Effect on Tomato Pollen Viability and Calcium Dynamics Under Heat Stress
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Paper Trails
No full textMy thesis exhibition, Paper Trails (2025), is made up of six artworks. The largest of the pieces are three paper tapestries (Tapestry #1 (2024), Tapestry #2 (2024), and Tapestry #3 (2024) which are three 2ft. x 6 ft. and are displayed vertically on the wall. They form a backdrop for two mixed media works, Rabbitbrush (2025), [a wire and paper interpretation] displayed at eye level on a pedestal and Bristlecone Pine (2025) [a sculpture made of cardboard and paper]. An additional work, Grid of Six (2025), is a mixed media series mounted on cleated boards. Lastly Book of Plants (2025) [a handmade book with letterpress printed species names and handwritten information accompanying collaged images of each of the plants listed]. Book of Plants (2025) is a guidebook viewers can consult to identify the plants in my artworks. All of the paper used in my pieces was handmade out of recycled materials.Paper Trails is my exploration of the native plant life of Nevada through the medium of handmade paper. Originally not from Nevada, I found the stark landscape and the lack of trees and greenery extremely depressing. In response, my art practice became an intentional search for the flora of the desert during my walks, seeking to uncover the beauty in the seemingly hostile environment. Inspired by pattern-focused artists such as William Morris, I incorporate patterns in my compositions, both natural and curated, to mirror the repetition in the act of physically searching out these plants. All paper in this exhibit was created out of office paper shreds that underwent a process of soaking, blending, dying, couching, drying, and finally being crafted into the final product. I value the meticulous and labor-intensive process of creation because I feel that human touch is lost in a society that only values speed in production. My use of handmade paper, instead of ready-made paper, is my way of fostering a deep connection with both the materials and the artistic forms they become. Through my practice, I highlight the resilience and quiet elegance of the desert plants that I had previously overlooked