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Conservation Laws for Asymptotically Perfect Fluid Spacetimes
Get PDFIn physics, conservation laws, like those for energy or momentum, are powerful tools that help us understand how systems evolve and interact. In general relativity, where spacetime itself is curved by matter and energy, defining such conservation laws becomes especially subtle and complex. Traditional methods rely on idealized conditions like empty space or special symmetries, which limit their usefulness in more realistic, dynamic settings such as an expanding universe.
This dissertation explores a modern mathematical framework, developed by Iyer and Wald, that allows conservation laws to be derived directly from the equations governing spacetime. Using this approach, I examine not only known solutions involving empty space (vacuum spacetimes) but also more realistic models that include matter, such as perfect fluids. Perfect fluids are often used to model stars, galaxies, and the large-scale behavior of the universe itself.
The main achievement of this work is the development of a new conservation law tailored for spacetimes that resemble a perfect fluid at large distances—just like the universe described by the standard model of cosmology. This result is then tested using the McVittie solution, which describes a massive object embedded in an expanding universe. I also explore a two-dimensional spacetime model known as dilaton gravity, revealing conservation laws in that setting as well.
In addition to the theoretical results, I created symbolic computer code to automate these calculations, making it easier for others to apply these methods to new models in the future. Overall, this work extends our ability to understand conserved quantities in more realistic and dynamic spacetimes, with applications ranging from astrophysics to cosmology
A Simple Sonication Method for Generating Monodispersed Nanoparticles of Hydrophobic Antioxidants
No full textVarious hydrophobic antioxidants remain unexplored for the treatment of space radiation and oxidative stress due to their inability to enter the cell without a drug delivery vehicle as their surface properties cause them to suffer from a poor solubility. In this paper you will find a recent breakthrough of a new method to create neat antioxidant nanoparticles free of any surfactant whatsoever vastly improving inherent solubility. These nanoparticles are synthesized monodispersed with a low polydispersity. This is even more suitable for astronauts then other generation methods, as the cocktail is without any solvent or surfactant which can have unknown effects on the body in space conditions. This research paves the way for new antioxidants to be used to protect astronauts from diseases caused by space conditions such as radiation and microgravity
Nitrogen Form Determines Lettuce Yield in Continually Replanted Systems
No full textNitrogen (N) recycling is essential in closed root-zones for bioregenerative life support in crewed missions. Microorganisms recycle organic N forms from human waste into ammonium and nitrate for plant growth. We used lettuce as a model crop to examine yield under multiple N sources modelled from N recycling. Plants were grown in peat moss media adjusted to pH 6 or 7 for five repeated plantings in the same containers without replacing the media. A nutrient solution was used for both studies that contained N as either ammonium nitrate, ammonium, nitrate, urea, or microbial biomass from the N-fixing microorganism Azotobacter vinelandii. Plants grown with N from ammonium, urea, or microbial biomass had reduced yields during the first planting compared to the other treatments, but this yield discrepancy diminished in following plantings. Plants grown in containers receiving ammonium nitrate tended to have the most stable yield overtime. These results demonstrate that lettuce yield is improved with a mixture of N forms, and that sufficient microbial communities must develop before nitrification is established
Scalable Compliant Louvres Manufactured via Sheet Lamination
No full textAs space missions increase, relying on Earth-based supply chains for spacecraft components becomes increasingly unsustainable. In-Space Manufacturing (ISM) offers an alternative, yet many fabrication methods depend on gravity, utilize hazardous materials, require large amounts of energy, or introduce thermal challenges in spacecraft environments. Sheet materials show strong potential for ISM because they store and transport efficiently, offer functionalization options, and provide robust in-plane properties. However, most sheet-based manufacturing techniques require bulky equipment ill-suited for on-orbit deployment. Sheet Lamination (ShL), an underutilized additive manufacturing process that bonds and cuts thin sheets to create near-net-shape parts, presents a compact and scalable alternative, although its viability remains underexplored.
At the same time, heat management poses a major challenge in spacecraft environments, particularly as manufacturing processes themselves can generate thermal loads that must be controlled. Louvres are a common approach to regulating spacecraft heat, but they can be heavy and mechanically complex. While compliant louvres offer lightweight, single-assembly designs, gaps in fabrication methods and kinematic reliability have hindered widespread adoption, underscoring the need for manufacturing solutions compatible with on-orbit conditions.
This work validates the potential of ShL to produce varied mechanisms by focusing on flexible, single-piece compliant louvres as a case study. We show that ShL minimizes material waste, requires little storage, and preserves radiative insulation performance—key factors for both terrestrial and in-space applications. The findings underscore ShL\u27s broader utility in addressing the dual challenges of efficient manufacturing and effective thermal control, paving the way for deployable and shape-changing structures in future space missions
Optimizing Continuous Wave Nd:YVO\u3csub\u3e4\u3c/sub\u3e Laser Performance for Longwave Infrared Generation
No full textThe Photonic Fury research group is working to create a nonlinear optical (NLO) system to scan human tissue for early warning signs of disease
Testing of an Acousto-Optic Modulator for Implementation as a Laser Q-Switch
No full textLong wave infrared (LWIR) spectroscopy can detect early disease indicators in human tissue by measuring wavelength dependent absorption of specific molecules. Despite its effectiveness, this technique is not widely used due to the high cost and slow speed of LWIR detectors. Additionally, typical LWIR light sources, like quantum cascade lasers (QCL), are challenging to tune over very wide wavelength ranges, limiting the types of molecules and diseases that can be probed
Enhanced 3D Image Reconstruction Using Scattered Light Tomography
No full textCoherent diffraction imaging (CDI) is a powerful technique for reconstructing phase shifts occurring in biological samples by capturing the interference between scattered light. These diffraction patterns contain spectral information, where shorter wavelengths (higher spatial frequencies) yield images with enhanced spatial resolution, improving detail and accuracy. However, higher spatial frequencies are located further from the central axis, rendering them fainter and more challenging to measure. To address this, our group developed a gyroscopic CDI system featuring a rotating platform driven by a stepper motor. This platform positions the sample between a broadband light source and a beam profiler, which are mounted on opposite sides, enabling precise rotation for enhanced data collection. This innovative system maintains normal incidence between scattered light and the detector, enabling accurate measurement of faint short-wavelength signals without compromising resolution
Lunar Landscaping: Designing a Berm-Building Robot for NASA Lunabotics
No full textThe goal of the NASA Artemis missions are to establish long-term human presence on the moon. This year\u27s NASA Lunabotics competition tasks teams with building robots capable of traversing and landscaping in a simulated Lunar terrain to gather data on Lunar construction. The competition goal is to construct a robot capable of building a berm out of regolith simulant. A diagram of the competition layout is shown in Figure 1
Investigating Temporally Dynamic Models of Choice in Rats and Bumblebees
Get PDFTemporally dynamic models of choice simulate how animals use past experience to make optimal decisions in variable environments. Chapter 1 briefly reviews a series of such modeling approaches and their mathematical properties. Extension of these models to longer experiments (more than 48 hours) designed to produce spontaneous recovery of choice (a behavioral phenomenon implicated in relapse) previously led to results not described well by current models. Chapter 2 comprises an empirical investigation of different explanations for these inconsistent results using rats, evaluating the effect of different test delays on preference following varied reward conditions. The results of the first two experiments ruled out the possibility of time’s passage alone causing animals to revert to exploratory behavior and suggested such an effect depends on reward variability only at the end of training. A third experiment aimed to distinguish a drift toward exploratory behavior produced by time’s passage can be distinguished from the effect of spontaneous recovery of choice, but produced inconclusive results, leading to a discussion of limitations of the current experimental preparation, alternative modeling approaches, and potential directions for further investigation. Chapter 3 provides a comprehensive review of literature on the suitability of bumblebees for choice research, then details an experimental investigation of the occurrence of spontaneous recovery of choice in B. impatiens. Results from this experiment suggested spontaneous recovery of choice did not occur. Explanations for these results and their generalizability are discussed. Chapter 4 summarizes overall conclusions and directions for future research
Utah Farmers Market Consumer Preferences for Local Cut Flowers
Get PDFIn this fact sheet, we review the results of a 2024 study examining consumer preferences for local cut flowers at Utah farmers markets. Study data were collected in person via Qualtrics at six farmers markets across northern Utah, with 51 total responses. We discuss farmers market consumer purchasing preferences, familiarity with labeling programs, and preferred flower colors and varieties. Additionally, the factors influencing consumer decisions when purchasing cut flowers, as well as the product information they rely on, are discussed. Overall, the information in this fact sheet will assist cut flower growers in making informed decisions regarding production methods and marketing strategies