Master's Theses (Plan A and Professional Engineering Design Projects)

Persistent link for this collection

https://hdl.handle.net/11299/53656

Search within Master's Theses (Plan A and Professional Engineering Design Projects)

Browse

Now showing 1 - 20 of 4662

Smart E-Textiles Integrated into Human Health Monitoring Systems
(2023-06) Carlson, Sam
E-textiles, broadly defined as any textile that has electronic capabilities, are becoming the future of portable, wearable electronics for human performance and health monitoring. There are many applications of e-textiles in the health monitoring industry, where early detection and prevention of adverse health conditions is at the forefront of concern. To illustrate the potential of e-textile monitoring in health care, two applications of health monitoring were chosen: monitoring respiratory rate and monitoring the dyadic interactions between a parent and their infant, specifically kangaroo care. As one of the primary applications examined, respiratory rate monitoring was chosen due to the documented omission of measurement for this known vital metric, which is key in detecting oncoming health decline. To address the need for better respiratory rate monitoring, an existing e-textile that was designed to monitor respiratory rate was redesigned for improved fit and accuracy. Piezoelectric energy harvesting was explored as a possible power source for using this e-textile as a completely portable device. Not only was developing an e-textile to measuring respiratory rate monitoring explored but integrating other devices into an e-textile system was demonstrated. Monitoring the dyadic interactions between a parent and their newborn infant is a complex procedure involving a variety of devices that must communicate effectively. A system that monitors the interactions between the parent and their infant was presented, and one component of the system was tested for its remote data collection capabilities. By experimenting with these two widely different health monitoring applications, the flexibility of e-textiles in both physicality and applicability was demonstrated. There is great potential for e-textiles to revolutionize health monitoring in healthcare settings and beyond, and more research and device development is required to achieve lasting positive impacts on the healthcare industry.
Engineering of the quorum quenching lactonase GcL for altered substrate specificity by rational design
(2022-06) Bravo, Joseph
Quorum sensing refers to bacterial communication systems based on a signal molecule that is produced and diffuses into the environment. The concentration of this signal in the environment allows for the behavior to be controlled in a cell-density dependent manner. Quorum sensing systems utilizing Acyl Homoserine Lactones (AHLs) are prominent in many microbial organisms and communities of high impact to human interests. These include certain agricultural and human pathogens, biofilm production, and aquatic biofouling. The structure of AHLs is variable and these structural changes determine the specificity of the signal. Several strategies that interfere with quorum sensing are naturally used by various organisms. One such strategy is to use enzymes that degrade the AHL signal, known as Quorum Quenching (QQ). Previously characterized QQ enzymes have exhibited a broad range of AHL specificity. To broaden the ability of QQ approaches, we decided to create QQ enzymes with increased AHL specificity. This presents a challenge, as we wish to avoid altering the active site catalysis while altering the specificity of the hydrophobic acyl chain of the substrate. We used the broad spectrum, thermostable lactonase from Parageobacillus caldoxylosilyticus, dubbed GcL, as a starting point of our rational design approach. Previously determined crystal structures of GcL uncovered key positions in substrate binding cleft that interact with the AHL substrate’s acyl tail. These positions were used as targets for site saturation mutagenesis, and several mutants with altered substrate preference were identified in a screening step and confirmed with purified enzyme and kinetic characterization. Several mutations were combined, and the best mutants obtained thus far have shifted substrate preference by up to 200-fold in favor of short-chain AHL. These mutants were crystallized, and their structures revealed a reshaping of the active site binding cleft, as well as an alternate substrate binding conformation for a prominent active site loop, which explains the changes in kinetic properties.
Experimental Validation of Convection-Enhanced Brine Evaporation: Trials at Bench-Scale and Pilot-Scale
(2023-06) Brown, Trenton
With the increase in use of desalination technologies to meet freshwater requirements, there is an increase in brine production and associated need for brine management solutions. Current brine management solutions are economically and environmentally unsustainable, particularly for inland desalination plants and small-volume (<100 m^3$/day) facilities. Convection enhanced evaporation (CEE) is a modular brine volume reduction strategy with the potential to be an economically feasible solution for these inland and small-volume industries. A mathematical model that predicts the evaporation behavior of the CEE system was previously developed in the Wright Lab. The objective of this thesis was to validate the model-predicted parametric behavior of the CEE system using a single tray bench-scale system, and to test a full-scale unit in the field to better understand practical limitations. In the lab, the modeled evaporation rate was compared to the experimental evaporation rate while controlling injection temperature, injection flow rate, air speed, and the salinity of the fluid for a single tray system. The model predicted the evaporation rate of deionized water with average absolute error of 28.6% and predicted the evaporation rate of salt water with an average absolute error of 9.4%. Overall, the model demonstrated good parametric correlation for the single tray system with controlled inputs; error appears to be associated with under prediction of the evaporation rate at low injection rates and over prediction of the evaporation rate at higher flow rates. Full-scale trials in Alamogordo, New Mexico were conducted over the course of seven days. Initial findings indicate the need for pulsed injection in order to obtain even vertical distribution across the stack of trays. The overall evaporation trends align with the model, with the cumulative daily evaporation varying from 5% to 67% absolute error against the experimental results. Further work is needed to test the field system with real brine streams, over varied weather conditions, and over extended periods of time.
An Investigation Into Ground Glass-Based Alkali Activated Cement For Use In High-Temperature Applications
(Spring 2024) Broemer, Garrett
Glass-based alkali-activated cements (AACs) can withstand higher temperatures, up to 1100°C, compared to conventional portland cement (PC) failing above 200°C. AACs demonstrate beneficial vitrification, and expansive foam properties different from PC. AACs are manufactured using a reactive aluminosilicate powder mixed with concentrated alkali solution to dissolve and polymerize aluminosilicate precursors creating a binding matrix. Glass-based AAC mortar was exposed to 300, 600, 900, and 1100ºC, then air cooled and water quenched to determine the residual compressive strength of the samples as compared to PC and fly ash-based AAC. AACs retained higher flexural modulus at ambient temperatures and higher residual compressive strength properties compared to PC. Physical property characterization was completed on the glass-based AACs, retaining similar porosity, density, and leaching but better insulative properties compared to PC. Alkali-activated cements demonstrate beneficial insulative properties that could be effective in fire retardant coatings, passive heat protection, or other high temperature applications.
Experimental Studies of Physics-Driven Segregation Patterns on Alluvial Fans
(2024-06) Axtell, Robert
Alluvial fans are depositional geomorphologic features often found where an upland drainage basin emerges from a mountain range. They can form due to debris flows, which carry and deposit water, boulders, and sediment from steeper slopes. Debris flows have a tendency to dynamically segregate particles of different sizes as they travel downslope, creating segregation patterns observable on alluvial fans. To study segregation dynamics in debris flows, we build experimental alluvial fan deposits. We independently vary the amount of clay and the grain size distribution of sand to study the effects on the segregation patterns on the resulting deposit. We found that there is a consistent downfan coarsening trend of sediment down the centerline of the resulting deposit for all of our experiments due to the active segregation in debris flows. This was true except for the smallest sand of experiments with high clay contents.
Understanding human activities and global w“o”rming and its impacts on soil properties and temperature in a Minnesota hardwood forest
(2023-05) Baumann, Tyler
Invasive earthworms create widespread ecological changes after they are introduced.Exotic earthworms are transported mainly through anthropogenically-mediated activities, including fishing, agriculture, horticulture, and development. Here, we use a conceptual framework to review the ways in which exotic earthworms are transported to new environments. This conceptual framework involves invasion filters (human activities filter and climate & edaphic filter) that constrain which exotic earthworm species can be transported within specific contexts. Differences in earthworms’ ecological behaviors, life cycle, and physiological tolerance of environmental conditions influence which species are transported and which regions can successfully be invaded. Within the human activities filter, we utilize the pathways of invasion laid out by Hulme et al. 2008, including release, escape, contaminant, stowaway, corridor, and unaided. These pathways follow a continuum of human intention; five of these pathways are associated with human activity: with release, escape, and contaminant pathways related to commodities, and stowaway plus corridor related to transport infrastructure. We find that the major human activities that transport exotic earthworms include discarding of fishing bait, agriculture, composting and horticulture, and development (e.g. the construction of roads, trails, houses, or campgrounds). Our review finds that although a diverse number of human activities transport exotic earthworms, the magnitude that specific activities transport earthworms is vastly understudied. We conclude that more research needs to be conducted to understand the methods that transport exotic earthworms in order to slow their spread. In the Upper Midwest, temperate hardwood forests have been heavily altered followingthe introduction of invasive earthworms of European, and more recently, Asian origin. Earthworms significantly modify the biological, chemical, and physical composition of soils in these ecosystems by mixing overlying organic horizons with underlying mineral soil layers. The recent invasion of these forests dominated by invasive European earthworms (Lumbricus terrestris, Lumbricus rubellus, Aporrectodea spp.) by ‘jumping worms’ (Amynthas agrestis and Amynthas tokioensis) has created profound and distinct changes to the soil that are not well understood. We surveyed forests at the University of Minnesota Landscape Arboretum in 2020 and 2021 and established transects with discrete areas of European or jumping worm dominance. We found that these discrete areas had distinct soil features and that jumping worm populations appear to replace Lumbricus spp. populations. Soils in areas dominated by jumping worms had a loose, granular casting layer near the surface, decreased bulk density, increased soil organic matter, increased pH, and higher leaf litter mass than soils in sites dominated by European earthworms. We also measured lower monthly average soil temperature, lower maximum soil temperature, and lower soil temperature variability in our jumping worm dominated sites. Our soil temperature results indicate that Amynthas spp. will not be limited by soil temperatures in advancing much further north than central Minnesota. It remains to be seen how invasive earthworm populations and soil properties will evolve with the continued invasion of jumping worms in the long-term.
Observed and Drift Diffusion Modeled Performance in Early Psychosis: Decreased Drift Rates and Bias in a Cognitive Control Task
(2024) Arend, Jessica
People with psychosis show specific deficits in cognitive control when examined using expectancy AX paradigms. Conventionally, metrics such as error rates, reaction times, and d’ statistics are used to parse differences across groups and task conditions. However, the computational mechanisms of cognitive control in psychosis remain elusive. Hierarchical drift diffusion modeling (hDDM) can help interpret the underlying mechanisms of cognitive control and its interruptions. In this study, a transdiagnostic sample of 56 people with early psychosis (EP) and 57 demographically-similar controls completed a novel variant of the expectancy AX paradigm known as the Translational Orientation Pattern eXpectancy (TOPX) task. We applied conventional metrics as well as hDDM to characterize TOPX performance. EP participants showed cognitive control deficits on conventional metrics (error rates, d’) as well as hDDM parameters. Specifically, people with EP showed slower drift rates on AX, BX, and BY trials compared to controls, as well as lower decision thresholds on AX trials and decreased bias towards A cues. This research suggests that among individuals with early psychosis, evidence accumulation is slower and less efficient, less evidence is utilized for decision-making, and representations and integration of contextual information is impaired. Further research is necessary to optimize the psychometric reliability of hDDM in cognitive control tasks as well as the clinical correlates of hDDM parameters.
(Un)even Terrain: Queer and Trans Staff Experiences Building Affinity, Community, and Kinship at the University of Minnesota
(2024-06) Williams, John
In the United States, there is currently an alarming rise in legislative attacks on queer and trans people through an increase in anti-LGBTQ+ rhetoric and over 515 anti-LGBTQ+ bills being tracked by American Civil Liberties Union (see Figure 1; ACLU, 2024). This wave of legislative hostility towards queer and trans people, compounded by simultaneous efforts against critical race theory (CRT) and diversity, equity, and inclusion (DEI), magnifies the impact on queer and trans people of color (QTPOC), who already face intersecting forms of discrimination and marginalization. These bills and rhetoric reinforce racism, heterosexism, and trans oppression that negatively impact and shape conditions for queer and trans people in U.S. educational settings (Duran & Coloma, 2023). At the same time, there has been a heightened visibility of queer and trans people in higher education and growth in the presence of Gender and Sexuality Centers (GSCs) on college and university campuses. This increased visibility and presence of GSCs coincided with greater attention on queer and trans student identity development with a greater understanding of intersecting identities (e.g., Duran et al., 2017; Goode-Cross & Good, 2009; Goode-Cross & Tager, 2011; Narui, 2011) and assessments of campus climate (Lange et al., 2019; Pryor & Hoffman, 2021; Pryor et al., 2023; Renn, 2010). However, much of the scholarship has centered on the student experience, while queer and trans staff remain an under-researched population in the study of higher education, especially queer and trans staff and faculty of color (Aguilar & Johnson, 2017; Renn, 2010; e.g., Sérráno & Gonzalez, 2022). This study explores the experiences of queer and trans higher education staff who work outside of GSCs. While GSCs serve as vital roles for support and advocacy, there exists a significant number of queer and trans staff who navigate landscapes outside these designated spaces, where acceptance and safety may be less assured. By focusing on this demographic, this research aims to fill critical gaps in existing literature and broaden the discourse surrounding queer and trans experiences in academia and shift the narrative to include how they are building community, affinity, and kinship.
Evaluating the Effectiveness of Health Recommendations based on Sensor data to Support College Students' Well-being
(2024-06) Putta, Mamatha
Stress management is difficult for college students as college can be very demanding. Stress can contribute to serious health issues, if not timely addressed, in an individual and is a critical problem. Recent studies have highlighted the growing prevalence and severity of mental health issues among college students, exacerbated by factors such as the COVID-19 pandemic and social isolation. The interest in examining technological interventions to support stress management is on the rise. Prior work has proposed a system that generates AI based recommendations for daily stress prevention/management. The recommendation system takes into account user's preferences for activities and self-reported well-being surveys to recommend stress relievers. However, this approach is limited to one snapshot event and relies on self-report data. To address this problem, this thesis focuses on using wearable sensors to get a continuous perspective of the user's day to improve the recommendation systems' performance and user experience. We integrated wearable sensor data (i.e., Garmin activity tracker watch) within the recommendation system to track the user's daily activity levels along with the user's stress and sleep levels. We thus conducted three rounds of testing with different prioritization levels, to evaluate the recommendation system with sensor data. The evaluation study demonstrated that the model performed optimally in the second testing round with an accuracy of 94\%, validating our hypothesis by predicting the category of activities that users have not engaged in. This supports our goal of fostering diverse activity recommendations to encourage well-being. Furthermore, the user study of 20 college students revealed that the sensor-integrated system significantly improved their motivation towards self-care, with participants notably preferring the personalized, actionable health recommendations derived from real-time data. Our findings suggest that continuous monitoring via wearable sensors enhances the effectiveness of recommendation systems in stress management, offering substantial benefits in promoting healthier lifestyle choices among college students.
Hydraulic and Hydrologic Characteristics of Effective Sea Lamprey Barriers
(2024-06) Reynolds, Kassandra
A network of 494 lowermost barriers on tributaries of the Laurentian Great Lakes prevent invasive sea lamprey from accessing upstream spawning habitat. Most of the lowermost barriers are low-head dams that are designed to maintain a minimum vertical separation of 45 cm between the barrier crest and the downstream water level. Many barriers are unable to maintain the design criteria for all flows, yet still effectively prevent sea lamprey passage. The fact that some barriers continue to block sea lamprey passage even when inundated (i.e., the downstream water level rises above the barrier crest) suggests other hydraulic conditions near the barrier may limit passage. However, little is known about the in situ hydraulic conditions downstream of these barriers. It was hypothesized that barrier efficacy is partially dependent on downstream hydraulic characteristics related to velocity and turbulence. A physical modeling laboratory study was conducted with three sea lamprey barriers of varying historical efficacies. Experiment 1 used an Acoustic-Doppler Velocimeter (ADV) to provide a quantification of the hydraulic characteristics downstream of these barriers. Experiment 2 used a force sensor to quantify the vertical forces at the riverbed. The results of Experiment 1 showed that mean longitudinal velocity averaged across a horizontal upper cross section was strongly correlated with barrier efficacy. This variable was interpreted as a marker of large-scale turbulence. Experimental trials that yielded a mean longitudinal velocity less than 1.3 m/s were effective, while ineffective barriers had values greater than 1.3 m/s. Other highly correlated variables included energy dissipation rate and eddy length scale in the vertical direction. These three variables, along with hydraulic head and the gravitational constant, were combined to form a dimensionless barrier number. The barrier number can be used to categorize barrier efficacy, and ineffective barrier trials generally had higher barrier numbers than effective barrier trials. In Experiment 2, the calculated upward pressure exerted on the riverbed peaked at -0.44 kPa. Since sea lamprey can produce suction pressures that overcome the -0.44 kPa peak pressure, the vertical upward pressures downstream of barriers are not likely capable of detaching a sea lamprey from the riverbed. Vertical force at the riverbed, therefore, is not likely an important variable to barrier efficacy. Together, the two experiments present a unified conclusion that the conditions near the riverbed are not as important to barrier efficacy as the conditions higher above the riverbed at 50% of the crest height. An improved understanding of how existing barriers block sea lamprey movement will aid in the design of future effective sea lamprey barriers.
The Influence of Epistemic Trust on Children's Phonetic Imitation
(2024-06) Sumner, Allie
Introduction: Previous studies have shown that children’s epistemic trust has an impact on object label learning (Koenig & Harris, 2005), and that children and adults spontaneously imitate phonetic detail in speech they hear (Nielsen, 2014). Objectives: The primary objective of this study is to determine if epistemic trust has an impact on children’s phonetic imitation, and if that impact follows the same patterns as object label learning and phonetic imitation by exposure. Methods: This experiment consisted of 5 parts, the baseline recording, familiarization trials, test trials, exposure phase, and post-exposure recording. The baseline VOT of a set of /p/ and /k/ initial words was measured before participants were exposed to two speakers, one who accurately labeled objects and one who did not. Participants were then asked to endorse one of the speakers as being knowledgeable over the other before they were exposed to either the reliable or unreliable speaker reciting the list of target words with either a lengthened or un-lengthened VOT. Post-exposure VOT was then measured. Results: 48 children were included in the analysis of pre- and post-exposure VOT. While the interaction between epistemic trust and phonetic imitation was not statistically significant, there was a significant four-way interaction between age, exposure phase, reliability of speaker, and modified or unmodified VOT. Conclusion: Phonetic imitation is not straightforward, and further research is needed to determine which factors play a role in a speaker's degree of phonetic imitation. It is possible that phonetic imitation is a more automatic process that is highly dependent upon task design and is not as easily influenced by a factor like epistemic trust.
Using Water Budgets and Isotope Analysis to Explore Water Availability in Low Flow Conditions: Hartley Pond Case Study
(2024) Olbertz, Madison
Quantifying seasonal changes to the volume and timing of water flowing through a reservoir provides valuable information for responsible resource management. Hartley Pond is a reservoir in Duluth, Minnesota, that is formed by a dam on Tischer Creek. Solar forcing to the reservoir elevates the summer water temperature to a level that is unhealthy for native Brook Trout. One option to address this impairment involves decoupling the stream from the pond. Tischer Creek would flow alongside the pond and maintain a natural water temperature while Hartley Pond would be fed by groundwater and excess streamflow during storm events. For this to work, water inputs from these sources must be high enough to sustain the pond without stream inputs under low flow conditions. To answer questions about the volume and sources of water discharge into and out of Hartley Pond, I built water budgets during low flow conditions in late summer. Streamflow, groundwater, precipitation, evaporation, runoff, and pond volume data were collected to build monthly water budgets for June, July, and August 2023. Accompanying stable isotope analysis of stream, pond, and groundwater samples refined elements of the water budget. Results from the water budget show that inputs into Hartley Pond are dominated by streamflow. Isotope analysis supports the finding that evaporation outputs are greater than groundwater inputs. Therefore, the plan to disconnect the stream from the pond may not be viable because the hydrologic integrity of the pond cannot be maintained through low flow conditions without streamflow inputs. Information gained from the water budget will help local resource managers create a feasible restoration project for Hartley Pond that meets community and environmental needs.
Utilizing Waste Material From Minnesota For Stormwater Management Purposes
(2024-05) Amoateng, Godbless
Minnesota's mineral, forestry, agriculture, and industrial activities generate substantial by-products and waste. Strategies to reuse or recycle these can reduce landfill waste, enhance public health, conserve resources, and cut costs and emissions. Building on the frameworks by Johnson et al. (2017), Saftner et al. (2019), and Saftner et al. (2022), this project extended its scope across Minnesota to include materials like dredge sediment from Mississippi River, RCA (recycled concrete aggregate) and VersaLime. Researchers identified, selected, and characterized various waste, by-products, and commercial materials statewide and tested engineered soil mixes for roadway foundations, assessing their stormwater retention and support for native plants. Laboratory methods characterized these mixes, which were implemented and evaluated in situ. A preliminary environmental life cycle assessment was also conducted, quantifying the environmental impacts of the engineered soil mixtures. Results were compiled into a design guide for the Minnesota Department of Transportation (MnDOT) engineers.
Predictive In-memory Multi-Level Indexing Algorithm for Spatiotemporal Trajectory Streams in Distributed Environments
(2024-06) Phung, Thanh Nam
Trajectory analysis has received significant contributions in recent years. With the rapid explosion of GPS-enabled devices, several large-scale datasets have been created, e.g., the Geolife GPS dataset (17,621 trajectories) and the bdd100k dataset (100,000 trajectories). This has provided enormous streaming spatiotemporal data, benefiting many real-world applications, e.g., urban planning, mapping services, and carpooling. These applications benefit from performing many types of search queries on spatial data, such as range query and join query. Despite the importance of these types of queries on streaming data, many systems do not support them. Many also fail to handle the scalability and efficiency problems when the input data is too large. This thesis proposes the first predictive in-memory multi-level indexing algorithm called PIMMLI. We introduced predictive indexing to enhance the scalability of the indexing process and compared it against an existing state-of-the-art algorithm called DITA. We have conducted extensive experiments on real-world streaming datasets and compared the performance of PIMMLI against DITA on different hyperparameters. Our results show that PIMMLI (1) has a similar range query performance with DITA; (2) has at least a 5.8% improvement in join query performance compared to DITA; (3) has an average improvement of 28.10% for trajectory indexing.
“Journaling into the void”: TikTok’s eudaimonic “web-weaving” and its digital practices
(2024-06) Moger, Rhys
This thesis uses a mixed-methods qualitative approach to analyze TikTok “web-weaving” (WW) slideshows and the user practices that go into their curation. WW slideshows include a collection of images such as Tumblr blog posts, illustrations, book quotes, and poems that are eudaimonic (i.e., emotionally poignant, existential, or vulnerable) set to music with a caption. Study 1 employs a textual analysis of 100 slideshows, totalling to 1,321 slides, to discover their eudaimonic themes and how such topics are discussed. Drawing upon Marx’s theory of alienation and humanistic psychology, I analyze how WW slideshows promote personal growth (as defined by Maurer et al., 2023) and counter-hegemonic sentiments that challenge what psychologist Stephen Joseph (2021) calls “the demands of conservative ideologies” (p. 7) such as individualism, productivity, and capitalist realism (Fisher, 2009). WW slideshows highlight the necessity of community, resting, engaging in creative activities outside of capitalist labor relations, and maintaining hope for imagined better futures (Grant, 2005). Study 2a explores seven interviewees’ eudaimonic motives for using TikTok and curating slideshows and what the multi-platform slideshow curation process entails. Study 2b details the same interviewees’ eudaimonic gratifications of WW: increased self-connection, a psychologically safe environment, and social connectedness. Together, these studies bring attention to online self-disclosure practices related to mental health and personal growth within current Western capitalistic culture via an interdisciplinary critical media effects framework (Ramasubramanian & Banjo, 2020).
3-Dimensional Changes in Position and Inclination of Ectopically Erupting Maxillary Canines in Response to Slow Maxillary Expansion: A Retrospective Study
(2024-04) Ng, Casey
At an incidence of 0.8-2.8%, the impacted maxillary canine constitutes one of the more challenging orthodontic problems to manage, often involving interdisciplinary coordination of surgical exposure of the impacted tooth followed by orthodontic traction to align the canine within the dental arch. In addition to the increased orthodontic treatment time, cost, and complexity, other sequelae of impacted canines include root resorption of adjacent teeth, cyst formation, and malocclusion. Interceptive treatment with maxillary expansion has been shown to reduce the risk of ectopically erupting canines (EECs) developing into impacted canines. Although effects of maxillary expansion on ectopic canine eruption have been studied, most have focused on rapid, rather than slow, maxillary expansion protocols and either clinical outcomes or canine localization on 2-dimensional imaging. Therefore, little is known about positional effects in the buccopalatal direction. The novel approach of investigating changes in eruption path in response to slow maxillary expansion based on cone beam computed tomography (CBCT) measurements was used in this study to facilitate precise localization of erupting maxillary canines in all 3 dimensions. In this retrospective study, CBCT records of 24 EECs treated with quad helix slow maxillary expansion (EEC 2x4 + QH group) were compared against those of 15 EECs treated with 2x4 fixed appliance (EEC 2x4 group, control treatment), 39 normally erupting canines (NECs) treated with quad helix appliance (NEC 2x4 + QH group, control diagnosis), and 24 NECs treated with 2x4 appliance (NEC 2x4 group). Linear and angular measurements pertaining to canine position and angulation were made in all 3 dimensions to determine differences at pre-treatment and post-treatment timepoints, as well as change across timepoints. Results showed that 67% of EECs corrected to a normal position, as defined by sector location, in both 2x4 appliance and quad helix appliance treatment groups. Significantly greater uprighting of the erupting canine angulation from a coronal view was found in EECs treated with 2x4 appliance, compared to EECs undergoing the same treatment. On the other hand, the quad helix appliance was found to significantly normalize medial displacement of EECs at cusp tip and apical levels, cause greater uprighting of the EEC inclination from a sagittal view compared to NEC controls, and maintain a normal vertical eruption rate in EECs. Therefore, the improvement in canine eruption path effected by the 2x4 appliance and quad helix appliance are brought about by mechanisms in differing planes of space.
SINful Consequences of Cover Cropping: Soil Inorganic Nitrogen (SIN) Provision and Retention from Warm-Season Cover Crops for Northern US Region Vegetable Production
(2023) Moses, Ezra
Warm-season cover crops are promising tools to meet vegetable crop nitrogen (N) demands while preventing N losses but more information is needed to achieve these goals in the northern US region. We explored warm-season cover crops in two rotations in Minnesota to evaluate biomass production, N provision and retention benefits, and impacts on vegetable yields. Warm-season cover crop biomass production ranged from 628-13,350 kg ha-1 and did not frequently exceed a weedy control. Soil nitrate decreased beneath cover crops and increased post-termination, demonstrating seasonal patterns potentially synchronous with vegetable demand. Cover crops reduced nitrate leaching to buried resin lysimeters by up to 50% but not significantly. Vegetable yields were often decreased following cover crop treatments, though legumes boosted vegetable yield in limited site-years. Evidence from this study suggests that warm-season cover crops could synchronize seasonal N patterns with vegetable demand but may not boost vegetable yields.
Addressing Production Bottlenecks of Emerging Nursery Crop Species in the Upper Midwest
(2024-06) Headley, Alyssa
Improved availability of emerging specialty crops will bolster species diversity in managed landscapes as well as fruit and nut production systems. This project encompasses two different studies that together address production bottlenecks in the nursery and highlight the value of developing protocols to facilitate the development of underutilized crops. Desert olive (Forestiera pubescens), a large shrub or small tree native to the southwestern United States, exhibits ornamental value and potential for broader application in managed landscapes. Purported tolerances to both drought and flooding suggest F. pubescens is well-suited for diversification of landscapes in urban settings and in green infrastructure. However, if this species is to be adopted by the nursery trade and produced on a large scale, propagation protocols need to be developed. Mouse ear disorder (MED) is an issue commonly encountered in container production of river birch and pecan, but may be more widespread. New protocols involving nickel treatment would enable and enhance the production of persimmon and hazelnuts, as well as create guidelines that protect growers and the environment.
“Are you spying on me?” The Impact of Data Sharing Extent on Consumers’ Perceived Surveillance and Responses Toward Online Behavioral Advertising
(2024-06) Li, Jingren
Online behavioral advertising (OBA) refers to the advertising practices of using consumers’ online activity data, such as their search and web browsing histories, to deliver personalized digital ads (Federal Trade Commission, 2009a). Although OBA enhances the advertising effects by delivering ads that are more personally relevant to consumers, its underlying extensive and intensive data monitoring practices also lead to consumers’ feelings of being watched and listened to by corporations, which is called "perceived surveillance." Given that consumers’ online activity data is commonly collected and shared across different digital platforms in OBA, and there exists a limited understanding of how consumers respond to these cross-platform OBA messages, the present study aims to investigate how the OBA data-sharing extent (cross-platform vs. within-platform) influences consumers’ perceived surveillance and subsequent advertising responses. Through an online experiment, this study found that consumers reported significantly higher levels of perceived surveillance when exposed to cross-platform OBA messages compared to within-platform ones. Furthermore, increased perceived surveillance was associated with higher levels of advertising avoidance and irritation, decreased attitudes toward the ad, the brand, and the publisher, as well as reduced click-through and purchase intentions.
Modifying Pharmaceutical Properties of Levofloxacin by Crystal Engineering
(2024-05) Huang, Pin-Syuan
The commercial form of a fluoroquinolone antibiotic, levofloxacin (Lev), is a hydrochloride salt (Lev-HCl). Lev-HCl possesses an intense bitter taste, which presents a challenge for developing an oral tablet with high patient compliance. We approached this challenge by preparing a sweet salt of Lev with an artificial sweetener, Acesulfame (Acs), through an anion exchange reaction. Solid-state properties of an anhydrous Lev-Acs salt were characterized using various analytical techniques. With a degradation temperature at about 260 °C, Lev-Acs is thermally more stable than Lev-HCl. Lev-Acs also exhibits approximately 3 orders of magnitude lower aqueous solubility than Lev-HCl. Both the lower aqueous solubility and the presence of a sweetener make Lev-Acs an excellent candidate for taste-masking. Lev-Acs exhibits superior tabletability at pressures below 150 MPa, attributed to its high plasticity. The results suggest that Lev-Acs holds promise for formulating a palatable tablet, addressing challenges associated with Lev-HCl. Based on analysis of five pairs of stoichiometric hydrates and corresponding anhydrates, it was hypothesized that higher plasticity of a hydrate is caused by a lower crystal packing efficiency and density. In these systems, all hydrates exhibit higher plasticity and lower packing efficiency. Thus, an example of a hydrate with a higher packing efficiency exhibiting lower plasticity would strengthen this hypothesis. Ideally, this can be observed for channel hydrates, where filling the channel space by water molecules increases crystal packing efficiency. In the absence of such an ideal model system, we have tested this hypothesis using a channeled hemi-methanol solvate of a levofloxacin acesulfame salt. Our results confirm this hypothesis since, compared to the isostructural anhydrate, the hemi-methanol solvate exhibits higher packing efficiency and lower plasticity. The higher plasticity of the solvate is confirmed by both crystal structure analysis and energy framework calculations. If this correlation between crystal packing efficiency and plasticity is robust, we can objectively predict material plasticity of structurally related crystals based on crystal packing efficiency.