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Ghost Gear Governance in the High Seas: A Content Analysis of Current International Governance Institutions
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Plastic pollution in marine environments has emerged as a global crisis, with abandoned, lost, or discarded fishing gear (ALDFG) posing a severe threat to the health and safety of the high seas. Despite growing public concern, international governance mechanisms for plastic fishing gear remain limited and fragmented, especially in areas beyond national jurisdiction. This honors thesis investigates the governance of ghost gear in the high seas through a content analysis of nine key international governance institutions’ documents. The analysis included keyword identification, qualitative content analysis, and relational content analysis using the Global Ghost Gear Initiative’s Best Practice Framework for the Management of Fishing Gear to evaluate the presence of prevention, mitigation, and remediation principles. Findings underscore the need for explicit integration of terms such as ALDFG, plastic, and gear in reference to ghost gear across governance documents to foster more consistent and effective global management. Results also highlight significant gaps in the use of mitigation and remediation terminology within these institutions. This research contributes to a growing body of evidence that supports the need for a more comprehensive and coordinated international governance approach to managing ghost gear in the high seas.
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sPHENIX 3-D Topological Calorimeter Cluster in RHIC Run-24 p+p Data
Get PDFThis thesis investigates the development and refinement of three-dimensional topological clustering techniques for the sPHENIX detector, focusing on proton-proton collisions as a pathway to study quark-gluon plasma dynamics. By optimizing energy reconstruction through meticulous calibration—addressing challenges such as noise cancellation and cluster splitting—the research demonstrates that the calibrated algorithm reliably reproduces the expected energy distributions across the electromagnetic and hadronic calorimeters. Comparative analyses with simulation data validate the algorithm’s performance and underscore its potential for enhancing jet substructure analysis. The findings also highlight anticipated challenges for future gold-gold collision experiments, suggesting that further refinement and integration of tracking data will be essential. Overall, this work lays a robust foundation for advanced data analysis in high-energy nuclear collisions, contributing critical insights into the study of fundamental particle interactions.
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Surface Charging of Objects by the Solar Wind Plasma and Energetic Neutral Particles
Get PDFSurface charging of objects in space is important for assessing electrostatic hazards to human and robotic exploration. Two experiments were conducted to study the charging environment of a lunar lava tube in a simulated solar wind plasma, and charging due to energetic neutral particle impacts on a solid surface. Secondary electron emission due to the impact of sub-keV ion and neutral particles was specifically investigated. In the lava tube experiment, a glass tube was exposed to a simulated solar wind flow in the Colorado Solar Wind Experiment (CSWE) device. A conducting surface was attached at the entrance of the tube and biased to various negative potentials to study the electron shielding effect on the charging conditions, and a planar probe was inserted at the bottom of the glass tube to measure the electrical potential and plasma conditions. The bottom surface potential is shown to be positive and increases with increasing ion kinetic energy and tube depth. This is a result of electrons being deposited on the side wall of the tube due to their thermal motions while kinetic ions move through the tube and charge the bottom surface positively. However, it's found that the bottom tube potential does not approach the ion kinetic energy even when solar wind electrons are nearly fully shielded from entering the tube. It is verified that ion generated secondary electrons from the sidewall of the tube partially neutralized the positive charge at the bottom. In the second experiment, the secondary electron yield from sub-keV ion and energetic neutral particle (ENP) impacts on a solid surface was investigated. ENPs were generated from ion-neutral charge-exchange collisions in the CSWE. It was found that the ion generated secondary electron yield is non-negligible, increases with the ion impact energy, and is much higher than the ENP generated secondary electron yield. ENP generated secondary electrons may become important for surface charging of objects such as a spacecraft flying through planetary atmospheres with a high neutral particle density. Additional tests on the dependence of incident particle mass and surface cleanliness were also investigated, showing that the secondary electron yield increases with lower mass incident particles and with a contaminated surface.</p
Shifting Diagnostic Paradigms: A Critical Analysis of Gender Dysphoria in the DSM-V-TR
Get PDFThis thesis critically examines the categorization of Gender Dysphoria (GD) within the DSM-V-TR, with the aim to prove that the medicalization and subsequent pathologization of gender identity have played a critical role in shaping public opinions about transgender individuals; specifically, legitimizing stigma and discrimination. Through historical accounts of non-cisnormative gender expressions, this thesis follows the evolution of trans identities from periods of relative tolerance to their current state as a diagnosable mental disorder. This study makes use of critical ideological paradigms and phenomenology in its design, including 11 semi-structured interviews that examine the lived experiences of non-cisnormative individuals.Through analysis of these interviews, this thesis focuses on social stigmatization, diagnostic encounters, healthcare, and the implications of GD’s classification as a mental disorder for accessing gender-affirming care.
The results of this thesis show the difficulties faced by non-cisnormative individuals when faced with the necessity of being diagnosed in order to receive (often life-saving) gender affirming care. It shows the intricacies of marginalization, recognition, patriarchal power structures, and the potential harm of pathologization. This study advocates for a shift away from the diagnostic paradigm set by the DSM to more affirming and more easily accessible care for all non-cisnormative individuals. In the current, staunchly anti-trans climate of United States politics, this thesis provides critical discussion on gender identity, pathologization, and social justice that advocates for more autonomy and equality in non-cisnormative healthcare practices.</p
The Wisdom to Know the Difference
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My Short film, Airplanes, dives into my personal feelings of guilt about winning the birth lottery, all that I have been given in my life, and how I have come to face that privilege. Through a combination of visuals, narration, and original music, I’ve made a confessional video journal that I feel will aid me as I continue to grapple with guilt and fear, and hopefully prompt others to think about their own feelings of guilt and privilege.
The paper that accompanies the film details the circumstances for privileged populations and outlines the existential guilt felt in these groups. I discuss what holds people back from achieving their full potential and how individuals obtain their own self actualization.
Together, the paper and film provide context into feelings of existential guilt and how we reconcile with the birth lottery. The film is meant to outline my personal struggles while the paper offers a more nuanced view of the topic. I wish to offer some clarity and recognition to these feelings because they are ones not often considered when examining the disparities in our society.
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The Impacts of Urbanization and Nest Temperature on Nestling Plumage Color in a Population of North American Barn Swallows
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An increasing amount of the human population lives in urban areas, and more cities are getting warmer due to the Urban Heat Island (UHI) effect. These rising temperatures can influence the physiology of wildlife due to a variety of factors, including changes in the developmental environment and varying survival in reaction to stressors. Past studies have found that certain physiological factors, like the production of melanin in avian species, can confer benefits for survival and reproduction in the face of environmental heat stressors. For North American Barn Swallows (Hirundo rustica erythrogaster), plumage color is a melanin-based, sexually-selected trait. As they nest on human structures and are therefore exposed to anthropogenic environmental effects such as the UHI, barn swallows living in hotter environments may be better adapted through the evolution and expression of darker plumage color. Here, I investigated the effects of urbanization and nest temperature on nestling plumage color in Boulder, Colorado, an area with a significant UHI. I quantified impervious surface area, average nest temperature, and average nestling brightness across a Boulder County urban-rural gradient. I found that urbanization and nest temperature were not correlated, and neither had a significant effect on nestling plumage color. This is inconsistent with previous studies’ findings on the environmental effects of UHI and introduces questions regarding Boulder’s specific environment and barn swallows’ interactions within their ecosystem. As wildlife continue to be impacted by human activity, it is increasingly important to understand whether and how they are adapting to anthropogenic stressors such as heat.
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Beach Combinatorics in Schur–Weyl Duality for the Upper Triangular Matrix Groups
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Schur–Weyl duality is a powerful result in representation theory that, in the classical case, relates the representation theory of the symmetric group with that of the general linear group. The link is established through a particularly natural tensor space on which both groups act, and these actions are compatible, with each action generating the full centralizer algebra of the other. Since the representation theory of the symmetric group is well understood, this connection greatly advanced our understanding of the representation theory of the general linear group. Analogs of Schur–Weyl duality have since been discovered for many groups and usually involve some interesting combinatorics, not unlike the classical case of the symmetric group and integer partition combinatorics. In this thesis, we study an analog for the unipotent upper triangular matrix group UTn(q) and investigate its centralizer algebra using supercharacter modules indexed by new combinatorial objects called beaches.
The unipotent upper triangular matrix group UTn(q) is well known to have a “wild” representation theory. In a practical sense, this means that the problem of describing the irreducible UTn(q) representations for all n and q is intractable. This difficulty drove the creation of supercharacter theory, which provides a way to coarsen the usual character theory for a finite group into something more manageable and allows one to study the representation theory of a group without needing to know its irreducibles.
Similar to other Schur–Weyl duality scenarios, we let the group algebra CUTn(q) act on a particularly natural tensor module (C-Span(Fn−1q ))⊗k . This module can be realized by repeatedly applying induction and restriction functors to the trivial UTn(q)-representation using a specific embedding of UTn−1(q) into UTn(q). We denote this module by Vn,k(q). In this thesis, we use a supercharacter theory for UTn(q) based on set partition combinatorics to investigate the centralizer iii algebra EndCUTn(q) (Vn,k(q)), which provides the dual action on Vn,k(q) for this analog of Schur– Weyl duality. We explicitly construct distinct supercharacter modules, called beach submodules due to their construction based on combinatorial structures called beaches, to yield an internal direct sum of Vn,k(q). This decomposition of Vn,k(q) is then used to obtain a collection of well-behaved centralizer maps called beach maps with extremely simple composition rules. Finally, we give a way to view beaches as much simpler matrices with entries in Fq rather than arrays of arc diagrams and use this to give a general expression for the difference between the dimension of the full centralizer algebra and the subspace spanned by beach maps. This expression is given as a polynomial in q − 1 with coefficients of the form Ai,j (k) n−1 j for nonnegative integers Ai,j (k), where i is the power of q − 1.
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Data-Driven Asteroid Tour Design
Get PDFAsteroids are remnants of the protoplanetary disk that surrounded the Sun during solar system formation. Understanding the composition of these time capsules is important to advance many areas of science, including solar system cosmochemical evolution, dynamical evolution of celestial bodies, and the origin of life on Earth.
Single-asteroid missions enable us to advance the state-of-the-art knowledge in many fields of science and engineering. Subsequently, asteroid tours, which are missions in which a single spacecraft conducts a series of visits with multiple asteroid targets, can enable even greater advancements and dramatically increase the science return of missions. However, asteroid tour design is a difficult endeavor due to the scope and structure of the design space.
This thesis presents a roadmap for a data-driven approach to asteroid tour design. First, we present an asteroid candidate filtering method and a tree-based asteroid tour construction tool that are used to stochastically produce a large set of feasible tour solutions. We demonstrate the use of this tool to generate Near Earth Asteroid and Main Belt Asteroid tour datasets containing a collective 1,681,218 asteroid tours. We analyze this tour data and demonstrate how it can provide insights into the solution space generally. We investigate various tour design aspects including initial candidate pool selection and exploitation of low-cost asteroids. We apply clustering to identify parameter constraints that are likely to yield low cost transfers and we present two methods of using clusters to inform asteroid candidate filter development. Ultimately, this thesis presents a data-driven asteroid tour design framework with broad applicability and potential to advance asteroid mission design and exploration.</p
Evidence-Based Strategies To Define, Differentiate, and Prevent Serious Injury and Fatality Exposure in Construction
Get PDFThe construction industry has made strides to prevent most injuries, yet the most severe ones continue to plague the industry at alarming rates. Construction organizations are still exposed to a similar risk of fatal injuries as in past decades. This issue has motivated researchers to question whether all types of injuries share the same causes, and whether they need the same management strategies. However, the lack of a shared definition on what constitutes a ‘serious’ injury, coupled with insufficient validation of serious injury and fatality (SIF) prevention strategies across multiple organizations limit how much we know about the effectiveness of SIF prevention efforts. To address this gap, this dissertation seeks to answer: How can organizations better define, differentiate, and reduce SIF exposure in construction sites? Therefore, the objectives of this dissertation were to (1) create an injury classification model for defining SIFs and validate this model through a noise experiment, (2) identify the unique precursors of SIFs that distinguish them from less serious-injuries through blind assessments from an expert panel and real injury cases, (3) measure and isolate the impact of energy-based safety training on the unique precursors of SIFs through a multiple baseline experiment, and (4) test the statistical relationships between the SIF differentiators and long-term injury rates. To demonstrate the experimental protocol and further test statistical relationships between the unique precursors of SIFs and injury rates, the study recruited more than 30 companies representing the utility, oil and gas, and construction sectors. This collaboration resulted in over 2000 field observations of pre-job safety meetings and physical construction work involving high-energy hazards.
The findings of this work demonstrate that short-term exposure to SIFs can be managed through better pre-job safety briefs and targeted controls of hazardous energy sources. Organizations that trained their crews on the energy wheel, high-energy hazards, and direct controls, were able to increase their proportion of direct controls for hazardous energy and the quality of their pre-job safety briefs by an average of 6.1%, and 15.7%, respectively. Furthermore, the findings show that shared definitions and consistent data collection protocols enhance the assessment of SIF prevention efforts, yet there is still more work to do to fine-tune the data collection process in the field. Future researchers may expand this work by testing other potentially unique precursors of SIFs, by validating or challenging these empirical findings with additional data, and by expanding the understanding of what is different about SIFs through qualitative interviews with front-line personnel. Practically, this work will potentially enhance the way that organizations measure the impact of their safety interventions and their return on investment. Methodologically, this work demonstrates the feasibility of running field experiments through industry collaboration to draw causal inferences on key safety initiatives.</p
Fluid Instabilities in Stellar Interiors: Fundamental Properties and Transport Processes
Get PDFFluid dynamical instabilities play a crucial role in the transport of heat in stellar interiors, and drive a wide variety of interesting phenomena. The highly turbulent and nonlinear nature of these instabilities, coupled with the need to resolve a challenging range of spatial and temporal scales, makes their behaviour difficult to predict and model. A long-standing problem in stellar modelling is parameterising transport and mixing processes in turbulent regions. This thesis presents a series of idealised numerical experiments exploring transport processes of fluid instabilities in stars.
The first of these experiments studies magnetohydrodynamic Rayleigh-Bénard convection (RBC), directly measuring force balances between the Lorentz, buoyancy, and inertial forces in order to quantify magnetic constraint. From these simulations we find three simulation regimes: a "constrained'' regime where the background magnetic field dominates, a "magnetically influenced'' regime where nonlinear Lorentz and inertial forces balance, and a transitional regime between the two. We have learned about a constrained yet turbulent regime for large external magnetic fields, where the traditional hydrodynamic scaling of the heat flux is recovered, despite inherently nonlinear effects from the Lorentz force.
The next of these studies focuses on simulations of thermohaline convective fronts in polluted white dwarfs (WDs). Current models of polluted white dwarfs often do not account for this effect, which can increase the inferred accretion rate by orders of magnitude when it is included. We find the turbulent flux of metals broadly dominates over the diffusive flux in a manner consistent with existing mixing prescriptions implemented in some stellar evolution models. Thus, our results broadly support polluted WD models that include thermohaline mixing in their estimates of the settling rate.
In the final study we focus on "parasitic" shear instabilities that saturate the thermohaline instability. Whilst most astrophysical flows have extremely high Reynolds and magnetic Reynolds numbers, these parasitic instabilities occur on small scales, where the effects of viscosity and resistivity are more significant. We find that linear stability analysis fails to predict the dynamical differences between low magnetic Reynolds number (Rm) flows and their higher Rm counterparts. we show that including viscosity and resistivity introduces two new modes of instability, one of which exists for any nonzero magnetic field strength as long as the magnetic Prandtl number, Pm< 1, and demonstrate numerically that this mode saturates in a quasi-stationary state dominated by counter-propagating solitons.</p
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