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Identifying Flood Source Areas and Analyzing High-Flow Extremes Under Changing Land Use, Land Cover, and Climate in the Gumara Watershed, Upper Blue Nile Basin, Ethiopia
No full textChanges in land use and land cover (LULC) and climate increasingly influence flood occurrences in the Gumara watershed, located in the Upper Blue Nile (UBN) basin of Ethiopia. This study assesses how these factors impact return period-based peak floods, flood source areas, and future high-flow extremes. Merged rainfall data (1981–2019) and ensemble means of four CMIP5 and four CMIP6 models were used for historical (1981–2005), near-future (2031–2055), and far-future (2056–2080) periods under representative concentration pathways (RCP4.5 and RCP8.5) and shared socioeconomic pathways (SSP2-4.5 and SSP5-8.5). Historical LULC data for the years 1985, 2000, 2010, and 2019 and projected LULC data under business-as-usual (BAU) and governance (GOV) scenarios for the years 2035 and 2065 were used along with rainfall data to analyze flood peaks. Flood simulation was performed using a calibrated Hydrologic Engineering Center–Hydrologic Modeling System (HEC-HMS) model. The unit flood response (UFR) approach ranked eight subwatersheds (W1–W8) by their contribution to peak flood magnitude at the main outlet, while flow duration curves (FDCs) of annual maximum (AM) flow series were used to analyze changes in high-flow extremes. For the observation period, maximum peak flood values of 211.7, 278.5, 359.5, 416.7, and 452.7 m3/s were estimated for 5-, 10-, 25-, 50-, and 100-year return periods, respectively, under the 2019 LULC condition. During this period, subwatersheds W4 and W6 were identified as major flood contributors with high flood index values. These findings highlight the need to prioritize these subwatersheds for targeted interventions to mitigate downstream flooding. In the future period, the highest flow is expected under the SSP5-8.5 (2056–2080) climate scenario combined with the BAU-2065 land use scenario. These findings underscore the importance of strategic land management and climate adaptation measures to reduce future flood risks. The methodology developed in this study, particularly the application of RF-MERGE data in flood studies, offers valuable insights into the existing knowledge base on flood modeling
Expanding the Low Earth Orbit Ecosystem with Mission Specific Reusable Spacecrafts: The CELL - Crew Enhanced Launchable Laboratory
No full textThe increasing demand for private orbital spaceflight has highlighted various issues with the current model for mankind’s experimentation and occupation of low earth orbit (LEO). Namely, there are numerous logistical and operational complexities with reaching and docking to a space station, safety concerns that arrive with orbital maintenance, and difficulties with reconfiguration to newer systems or different science equipment. This increased demand has further highlighted the need for a new model of orbital exploration, incorporating concepts such as mission specificity and brief stays independent from the complexities that arise from space stations. This thesis presents the comprehensive design and analysis of a spacecraft capable of supporting this role by introducing a reconfigurable interior capable of being redesigned to optimize each mission, allowing for highly optimized missions and faster turnaround between these missions, dubbed as the CELL (Crew-Enhanced Launchable Laboratory). The purpose of this spacecraft is to move away from the traditional ”Space Station” model of space exploration such as the International Space Station (ISS) and provide an avenue towards a mission specialized model with the ability for much faster deployment and turnaround. The types of missions this spacecraft should be capable of includes but is not limited to space tourism, time sensitive scientific research experiments, new technology and prototype demonstration, emergency rescue missions, and astronaut training operations. The design process incorporates mission requirements, such as autonomous operation, mass and volume efficiency, and power limitations, to evaluate subsystem compatibility and crew habitability through the use of various layered trade studies to reach an unbiased favorable decision. To highlight the theoretical mission capabilities and mission diversity of this model of space exploration, two different configurations of the CELL have been designed: an autonomous stem cell research laboratory and a general purpose human spaceflight configuration capable of housing a crew of 4 for short duration stays reaching up to seven days. Various different evaluation methodologies were used to evaluate the capabilities of the interior configurations, primarily using Virtual Reality (VR) and an unbiased VR framework. This research demonstrates that a spacecraft model such as the CELL is technically feasible and could open new avenues for space tourism, research missions, and commercial applications. It concludes by recommending future work on system testing, long-duration mission adaptations, and potential scalability for diverse mission profiles. This study contributes to the growing field of private space exploration by offering a blueprint for self-sufficient, human-centered spacecraft design
“And All God’s People Said”: Analyzing Christian Stereotypes Using the Linguistic Perception Gap Method
No full textAlthough Christianity is the majority religion in the US, it is still subject to stereotypes and prejudice. As this majority status has diminished, researchers have paid more attention to these biases. In the current study, I used language analysis and self-report measures to study Christian stereotypes. Using the linguistic perception gap method, I compared perceptions of sermon language to actual sermon language (Ns = 320) to reveal the accuracy, content, and valence of people’s stereotypes. I hypothesize Christians (Nc =172) would hold positive perceptions toward sermon language, while non-Christians (Nnc = 181) would hold negative perceptions consistent with ingroup favoritism and outgroup derogation. Additionally, I predicted all participants would perceive sermons as high in communion and competence language consistent with stereotype content theory, but that this would be more pronounced for Christians. Results were mixed with both groups overestimating positive and negative sermon language and no significant differences between the groups for communion and competence language. I discuss several theories that may explain the mixed results and future directions for the linguistic perception gap method
Transnational Families: Impact of Family Separation on the Mental Health of Latinx Young Adults Separated During Childhoodtransnational Families: Impact of Family Separation on the Mental Health of Latinx Young Adults Separated During Childhood
No full textThe forced migration of Latinx families, driven by civil unrest, poverty, and political persecution, has contributed to the rise of transnational families, where some members migrate while others remain in their home countries. The emotional and mental well-being of children left behind due to parental migration is a critical yet understudied issue. This research aimed to address this gap by exploring the complex relationships between parental separation, attachment security, emotion regulation, and mental health outcomes among Latinx young adults in Latin America. Utilizing secondary data from an international, online study, 67 Latinx young adults who experienced parental migration during childhood were compared to 67 matched peers (based on age, ethnicity, race, gender, and nationality) who did not experience parental migration. Through moderated mediation models, the study examined how parental separation and attachment security influenced emotion regulation and mental health outcomes. Three hypotheses were tested: first, that parental separation would be associated with greater mental health problems (e.g., internalizing, externalizing, and substance use); second, that difficulties in emotion regulation would mediate these relations; and third, that attachment security would moderate the relationship between separation and emotion regulation, with a stronger effect among participants with lower attachment security. The findings revealed that parental separation was not directly related to increased mental health problems, and attachment security did not moderate the relationship between separation and emotion regulation. However, emotion regulation difficulties consistently predicted greater mental health issues, underscoring its pivotal role in mental health interventions for Latinx populations
Relaxation and Actuation Dynamics of Complex Polymer Systems
No full textPolymers and soft matter exhibit versatile properties that enable transformative applications across diverse fields, including energy storage and soft robotics. This work investigates the behavior and functional potential of polymer-based systems, with a focus on coacervate materials and responsive actuators for bio-inspired robotics. Coacervates formed by Poly Diallyl dimethyl ammonium chloride (PDDA) and Adenosine Triphosphate (ATP) demonstrate exceptional sensitivity to weak electric fields (~1 V/cm), a response notably more pronounced than that of colloidal particles. Through dielectric relaxation spectroscopy (DRS), we reveal that these coacervates exhibit a dielectric permittivity comparable to advanced inorganic materials such as BaTiO3, commonly used in supercapacitors. This high dielectric constant not only explains their pronounced sensitivity but also suggests potential applications in high-energy-density storage systems and biofunctional formulations for wound healing. Furthermore, we examine the dependence of their dynamic relaxation behavior on parameters such as temperature, water content, and cohesive energy density, shedding light on their glassy states, fragility, and adaptability under varied conditions. Simultaneously, the development of polymer-based actuators is explored for applications in soft robotics. Three innovative materials are assessed: Nafion-based ionic polymer-metal composites (IPMCs), thermoresponsive chitosan hydrogels, and phase-change silicone elastomers embedded with ethanol micro-bubbles. IPMCs, enhanced through advanced ion exchange and platinum deposition, achieve low-voltage, rapid actuation ideal for precise bending motions. Chitosan hydrogels activated by infrared radiation demonstrate adaptable, controlled movements suited for delicate gripping tasks. Meanwhile, silicone elastomers utilize the liquid-to-gas phase transition of ethanol to achieve significant, energy-efficient expansion for large-deformation applications. These materials are characterized for their unique actuation behaviors, response times, and operational efficiencies, highlighting their integration potential in medical, industrial, and assistive robotic systems
The Role of Vimentin Peptide Citrullination in the Structure and Dynamics of HLA-DRB1 Rheumatoid Arthritis Risk-Associated Alleles
No full textCitrullination, a post-translational modification (PTM), plays a critical role in rheumatoid arthritis (RA) by triggering immune responses to citrullinated self-antigens. Some HLA-DRB1 genes encode molecules with the shared epitope (QKRAA/QRRAA) sequence in the peptide-binding groove which preferentially presents citrulline-modified peptides, like vimentin, that intensifies the immune response in RA. In this study, we used computational approaches to evaluate intermolecular interactions between vimentin peptide-ligands (with/without PTM) and HLA-DRB1 alleles associated with a significantly increased risk for RA development. Crystal structures for HLA-DRB1*04:01, *04:04, and *04:05 bound to citrullinated peptides (PDB ID: 4MCY, 4MD5, 6BIR) were retrieved from the Protein Data Bank and non-citrullinated 3D structures were generated by mutating citrulline to arginine. The pHLA complexes were submitted to four rounds (50 ns each) of molecular dynamic simulations (MD) with Gromacs v.2022. Our results show that citrulline strengthens the interaction between vimentin and the HLA-DRB1 molecules, therefore impacting both the peptide affinity to the HLAs and pHLA stability; it also induces more intermolecular hydrogen bond formation during MD in the pHLA. Citrulline prevents repulsion between amino acid 71β and the P4-residue of native vimentin. Thus, vimentin citrullination seems to affect pHLA binding and dynamics, which may influence RA-related immune responses
Lift Every Voice: A Qualitative Exploration of Black Parental Perspectives on Science, Technology, Engineering, and Math Through the Lens of School Choice
No full textBackground: School Choice is a gateway to STEM education and future career opportunities for many Black high school students residing in historically Black neighborhoods. With disproportionately low participation in School Choice, racist zoning practices, and inadequate funding models, a higher percentage of Black students find themselves in underperforming schools with limited access to STEM programs. With STEM careers increasing annually, STEM exposure in high schools offering this curriculum is critical. Purpose: The purpose of this study was to explore Black parents' experience in accessing STEM, school choice, and future STEM career options for their children. To identify if systemic racism or the Black experience in public schools influences parental decisions to refrain from accessing high school STEM options through School Choice, two research questions were posed: (1) How do Black American Parents understand School Choice as a method of accessing STEM options and STEM career opportunities for their children? (2) How do the Black American parents’ perceptions of School Choice and their experience in the American education system influence their decision to enroll their children in high school STEM options? Methods: This qualitative study used narrative inquiry to allow participants to share their experiences through semi-structured virtual interviews. Through convenience sampling, six parents or guardians of high school-age children were recruited to participate in this study. Participants identified as Black and resided in a historically Black neighborhood with high school-aged children attending the zoned school. Interview data was transcribed and analyzed thematically using the 6-step protocol (Clarke & Braun, 2013) to identify emerging themes. Findings: The study revealed that Black Parents equate their neighborhood with safety, help, and acceptance. The resources in historically Black neighborhoods were seen as unexchangeable and overruled any desire to seek STEM options through School Choice. Finally, the parents revealed that they would rather repair their zoned schools than search for a new one. Conclusion: The study contributed to the body of research surrounding the educational experiences of Black families as it created an opportunity for Black Parents to describe the complexity of making school enrollment decisions for their children
Engineering Bacterial Secretion of 2’3’ cGAMP for Therapeutics
No full textThe development of new vaccines and immunomodulators, especially those delivered to mucosal surfaces are crucial in the context of respiratory pathogens as well as gut-related illnesses. The discovery and validation of the stimulator of interferon genes (STING) pathway within the last two decades has spurred the development of STING agonists as potential immunotherapeutics for the treatment of cancer and as vaccine adjuvants for infectious diseases. In this dissertation we have engineered Escherichia coli (E. coli) to secrete the endogenous STING agonist 2’-3’ cyclic guanosine monophosphate–adenosine monophosphate (cGAMP). In the first half of this thesis, we have studied the production and purification process for cGAMP, from E. coli culture at lab-scale as a goal towards sustainable manufacturing. The process focused on the recombinant production of cGAMP via a whole-cell biocatalysis platform utilizing the murine cyclic Guanosine monophosphate–Adenosine monophosphate synthase (mcGAS). In E. coli BL21(DE3) cells, recombinant expression of mcGAS, a DNA-dependent enzyme, led to the secretion of cGAMP to the supernatants. For maximizing cGAMP production, we evaluated media composition, supplementation of divalent cations, temperature of protein expression, and amino acid substitutions pertaining to DNA binding. To simplify the downstream processing, we developed and validated a single-step purification process for cGAMP using anion exchange chromatography, and an endotoxin removal step. Unlike chemical synthesis, our method provides a route for the recombinant production of cGAMP without the need for organic solvents and supports the goal of moving towards shorter, more sustainable, and more environmentally friendly processes. In the second part of the thesis, we studied engineered commensal bacteria producing cGAMP, and their potential use as an immunomodulator in the gut mucosa. In the previously established E. coli MG1655 system producing cGAMP via the recombinant expression of mcGAS, we tested the ability of the bacterial culture to survive in the intestine, simulating a sub-optimal environment for its growth. We also tested the survivability of these bacteria in mouse gut via oral gavage studies, and distribution of bacteria throughout the intestinal tract
Evaluation of Machine Learning Assisted Phase Behavior Modelling of Surfactant–Oil–Water Systems
No full textThis paper evaluates the ability of machine learning (ML) algorithms to capture and reproduce complex multiphase behavior in surfactant–oil–water systems. The main objective of the paper is to evaluate the ability of machine learning algorithms to capture complex phase behavior of a surfactant–oil–water system in a controlled environment of known data generated via physical models. We evaluated several machine learning algorithms including decision trees, support vector machines (SVMs), k-nearest neighbors, and boosted trees. Moreover, the study integrates a novel graphical equation-of-state model with ML-generated compositional spaces to test ML’s effectiveness in predicting phase transitions and compares its performance to experimental data and a validated physical model. Our results demonstrate that the cubic SVM has the highest accuracy in capturing key behaviors, such as the shrinking of two-phase regions as salinity deviates from optimal conditions, and performs well even in near-extrapolated scenarios. Additionally, the graphical equation-of-state model aligns closely with both experimental data and the physical model, providing a robust framework for analyzing multiphase behavior. We do not suggest that machine learning models should replace traditional physical models, but rather should complement physical models by extending predictive capabilities, especially when experimental data are limited. This hybrid approach offers a promising method for investigating complex multiphase phenomena in surfactant systems
From the Foreland and Retroarc Thrust Belts to the Mantle Transition Zone: First Multi-Scale Retrodeformable Transect of the Active 90 mm/yr Taiwan Arc-Continent Collision
No full textThis dissertation presents integrated multi-scale retrodeformable transects of the Taiwan arc-continent collision. Chapter 1 presents reprocessed marine seismic reflection profiles of the retroarc thrust belt near Chimei Canyon offshore eastern Taiwan, which is one of the largest submarine canyons around Taiwan and results from the 100 Ma of pelagic sedimentation at abyssal depths prior to the onset of Eurasian subduction and arc volcanism at ~18-14 Ma. This onset is marked in the Huatung Basin by seismic facies that thicken arcward, including mass-transport deposits, in contrast with underlying 1-2 km thick pelagic facies. The contact between oceanic crust and the pelagic sequence provides a zone of detachment that is the locus of deep massive laccolithic intrusions at ~1 Ma imaged in our reprocessed seismic reflection profiles. The ~2-3 km thick roof stratigraphy has been flexed upward by 2-3.5 km laccolithic inflation. Chapter 3 presents progress towards a multi-scale retrodeformable transect across the entire orogen from the foreland and retroarc thrust belts to the mantle transition zone. Multiscale tomographies define two active east-dipping Eurasian and Luzon forearc subduction systems that detach from their upper crusts and form thin-skin foreland and retroarc thrust belts above fundamental detachments. A new retrodeformable cross-section that extends from the imbricated foreland to the metamorphic core defines the post 1 Ma structure of western Taiwan, which shows two detachment levels, imbricated fault-propagation folds and agrees with tomographic and resistivity images. The upper detachment is the Eurasian subduction interface, which is the roof thrust of a low velocity channel defining a mid-crustal duplex under Taiwan. The lower detachment defined by tremor seismicity and tomography is the floor thrust of the channel, which is currently active and probably results in uplift of the Taiwan mountain belt after 1 Ma