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EUROPEAN FOULBROOD IN UNITED STATES HONEY BEE COLONIES : PREVALENCE, PATHOGEN DIVERSITY AND MANAGEMENT STRATEGIES
No full textThesis (Ph.D.)--Michigan State University. Comparative Medicine and Integrative Biology - Doctor of Philosophy, 2025European foulbrood (EFB) is a bacterial disease of honey bee larvae caused by Melissococcus plutonius, with increasing prevalence reported across United States (US) apiaries over the past decade. Despite its significance to US apiculture, very little is known about regional (US) epidemiology, including pathogen prevalence, genetic diversity, antibiotic susceptibility, and environmental persistence. This dissertation seeks to fill some of these gaps though classical and molecular epidemiology, antimicrobial resistance testing, and environmental persistence studies which can inform evidence-based management strategies.Surveillance carried out between 2021 and 2022, including 855 colonies across 19 Michigan beekeeping operations, revealed high overall M. plutonius prevalence with 32% of colonies infected and marked seasonal patterns peaking in June when over 50% of colonies screened positive and over 20% had clinical EFB. Whole genome SNP analysis of 91 isolates revealed remarkable genetic diversity, identifying 24 unique genotypes spanning both typical (CC3) and atypical (CC12) clonal complexes. Most operations harbored multiple genotypes even within a single infected hive, suggesting complex transmission dynamics within and between apiaries.Antimicrobial susceptibility testing revealed no evidence of oxytetracycline resistance among genetically diverse M. plutonius isolates, with all minimum inhibitory concentrations (MIC) below 4 \u3bcg/ml. However, methodological factors including media composition, incubation time, and antibiotic degradation significantly influenced assay outcomes, highlighting the need for standardized protocols. Environmental persistence studies demonstrated that some atypical M. plutonius strains remain viable on hive materials for extended periods, persisting on wood and cloth for over 6 months at room temperature and in larval smears for more than three years. Disinfection efficacy varied by strain type and material, with 10% bleach achieving near complete elimination while 70% ethanol showed reduced efficacy against atypical and typical strains.Here we show EFB has become endemic among beekeepers of all types in Michigan, with many hives infected with multiple variants of M. plutonius suggesting high rates of transmission. While all strains screened show no evidence of resistance to oxytetracycline, all strains persist on media beyond the window of antibiotic efficacy which may explain recalcitrance and other methods of EFB management are desperately needed. While bleach showed high efficacy at reducing this environmental persistence in the lab, additional research is needed to determine efficacy in the field.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
THE PHOTON SPECTRUM AND FLUX DENSITY REGULATE BIOMASS ACCUMULATION AND MORPHOLOGY OF CULINARY HERBS GROWN INDOORS
No full textThesis (M.S.)--Michigan State University. Horticulture - Master of Science, 2025Blue light (B; 400\u2013499 nm) generally inhibits extension growth while far-red light (FR; 700\u2013750 nm) promotes stem elongation and leaf expansion. This research aimed to determine how B and FR light interact, and how FR light and the total photon flux density (TPFD; 400\u2013750 nm) interact, to regulate growth and quality characteristics of culinary herb transplants. Another objective was to determine whether effects of B light were primarily regulated by the B to red light (R; 600\u2013699 nm) ratio (B:R) or the B photon flux fraction (BPFF = B/TPFD). Basil, cilantro, parsley, sage, mint, and oregano were grown indoors under sole-source lighting from light-emitting diodes. Seeds were sown in 72-cell trays at a constant 23 \ub0C under a 16-h photoperiod for all studies. In the first study, BPFDs of 20, 60, or 100 \u3bcmol 19m 122 19s 121 were tested with either 0 or 60 \u3bcmol 19m 122 19s 121 of FR light, and R light added so that the TPFD was 210 \u3bcmol 19m 122 19s 121. In the second study, FR fractions of 0.0, 0.1, 0.2, and 0.3 were tested under TPFDs of 150, 250, and 350 \u3bcmol 19m 122 19s 121. In the third study, BPFFs of 0.1, 0.2, 0.3, and 0.4 were tested with 0, 45, or 90 \u3bcmol 19m 122 19s 121 of green light (G; 500\u2013599 nm), yielding twelve B:Rs, all with a TPFD of 300 \u3bcmol 19m 122 19s 121. FR light increased stem length, shoot growth, and specific leaf area, and decreased the root dry mass fraction of most species, and B light generally had opposite effects, but the presence and magnitude depended on the FR and B PFDs. FR light had similar effects in the second study, but the magnitude of the effect decreased as the TPFD increased. Increasing the BPFF and B:R inhibited stem elongation, biomass accumulation, and leaf expansion, but the magnitude of the effect occasionally decreased as G light increased, and the effects of the BPFF were more consistent than the B:R. These results advance our understanding of the complex photobiological responses that regulate plant growth and inform young plant growers and lighting companies about how to use light to control growth.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
THE EFFECT OF ADAPTIVE MOMENTUM ON RATES OF ADAPTATION
No full textThesis (Ph.D.)--Michigan State University. Integrative Biology - Doctor of Philosophy, 2025Populations don\u2019t evolve at a constant pace. This thesis introduces adaptive momentum, a framework for understanding bursts of evolutionary change that occur during periods of population flux\u2014such as selective sweeps, expansions, or recoveries from disruption. During these phases, purifying selection weakens, allowing mildly deleterious mutations to persist and increasing the population\u2019s capacity for genetic exploration.Adaptive momentum is not a new mechanism but a synthesis of well-understood evolutionary forces acting under transient, non-equilibrium conditions. It reframes and extends shifting balance theory by arguing that range-expansion-like dynamics are not rare edge cases, but routine features of adaptation. These dynamics briefly open new evolutionary pathways\u2014not through intention, but through relaxed constraints and altered selection landscapes.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
SODIUM CHLORIDE AND ROAD SALT SALINITY SURVIVORSHIP ACROSS AEDES SPECIES
No full textThesis (M.S.)--Michigan State University. Entomology - Master of Science, 2025Toxicology experiments have been widely used to determine the effects of many chemicals on Culicidae species, such as pesticides, insecticides, and herbicides. Some common chemicals that have not been studied widely among Culicidae species regarding their effects on their environment at the larval stages include road salt. Currently, there are about 60 species of Culicidae in Michigan, and they emerge during different seasons of the year. Road salt runoff and exposure to the main chemical, sodium chloride, affect many macroinvertebrates, including Culicidae. Road salt contains chemicals such as chloride, and the levels adjacent to main roads in Michigan could range from 18 to 2700mg1-1. The main species included in this study were the 4th instar of Ae. trivittatus, Ae. triseriatus and Ae. vexans. The experiment was conducted from July through September 2024. Field collections were conducted across three sites in Ingham and Clinton County. Laboratory experiments included three trials with two bioassays per trial across 30 replicates with 10 4th instar larvae in each replicate container and consisted of pond water, Di Water, 12mg/L, 120mg/L, 1200mg/L, and 12000mg/L salt treatments. The data analysis utilized Kaplan-Meier Survivorship Curves Summaries, Mantel-Cox Log-Rank Multiple Comparisons Test, and a manual toxicity survival assay test for replicate analyses that examined the effects of various road salt and sodium chloride doses. The most notable results in the study indicated that higher mortality rates occurred with Culicidae exposed to 12000mg/L of salt as opposed to low to medium doses (12mg/L, 120mg/L, and 1200mg/L) of salt. This research explored different frameworks for conducting bioassay experiments with 4th instar Aedes species across three different experiment trials and how to conduct bioassay methods for other chemicals, such as pesticides, to explore survivorship times and fatal doses. Most notably, the results led to lethal concentration times for the three species involved with road salt and sodium chloride.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
INDOOR MOLD CONCENTRATIONS, PREVALENCE, AND RELATION TO BUILDING CHARACTERISTICS IN HOMES IN VERY COLD CLIMATES
No full textThesis (M.S.)--Michigan State University. Civil Engineering - Master of Science, 2025People in the U.S. spend more than 90% of their time indoors. In extremely cold climates including Alaska (ASHRAE Climate Zone 8), homes provide essential shelter, yet these homes are often smaller, overcrowded, and not designed for the harsh cold climate that requires year-round heating. Extreme cold weather also creates potential condensation risk and thus the potential for mold growth. Previous research has found that many Alaska residents have concerns about mold growth in their homes and also has shown the prevalence of mold-induced respiratory infections and conditions particularly for children in these locations. However, it is rare for studies to quantify the concentration of mold or quantify its causes. This study utilized surface and airborne mold tests alongside in-person home assessments in 72 households in two rural coastal Alaskan communities. Results detected the potential for mold in the air of 39% of homes tested, and mold was found on at least one surface in 67% of homes tested. Nonparametric statistical tests were performed to analyze correlations between indoor mold concentrations and housing characteristics. Surface mold was more likely to be found in homes that were older, more densely occupied, were more humid, did not have Heat Recovery Ventilators (HRVs), or samples taken from windows. Airborne mold was significantly correlated with the community, indoor humidity, and room type. This study highlights the household characteristics that potentially indicate the air and surface mold growth status in homes in very cold climates.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
ASSESSING THE IMPACTS OF POSTED SPEED LIMITS AND ROADWAY DESIGN ELEMENTS ON DRIVER SPEED SELECTION BEHAVIOR
No full textThesis (Ph.D.)--Michigan State University. Civil Engineering - Doctor of Philosophy, 2025Recently, speed management practices have shifted away from a historical focus on the 85th percentile speed toward a safe systems approach that promotes safer speeds in all roadway environments through a combination of thoughtful, equitable, and context-appropriate roadway design, appropriate speed limit setting, targeted education, outreach campaigns, and enforcement. This includes the use of roadway design elements to reduce speeds and create a more accommodating environment for all users. One important geometric feature that could be used in this context is a roundabout due to its ability to reduce conflict points and significantly improve safety as compared to other intersection designs. However, integrating roundabouts into a roadway poses many challenges, especially when accommodating vulnerable road users (VRUs), such as pedestrians and bicyclists.To that end, this study aims to inform the design process by advancing our understanding of how drivers adjust their speeds based on changes in the posted speed limit and other contextual factors related to the roadway environment. It also examines driver speed selection at roundabouts in the presence or absence of VRUs and how these speed profiles compare to those at signalized intersections and all-way stop controls, especially at the entry and exit approaches. To assess the effect of roadway characteristics on driver speed selection at speed transition zones, field data were collected from 19 highway corridors across Minnesota using handheld lidar guns to track drivers' operating speeds as they transitioned from high-speed rural highways to lower-speed rural and suburban communities. This resulted in the estimation of a series of speed reduction factors (SRFs), which detail the impacts of various site-specific characteristics, such as roundabouts, medians, and two-way left turn lanes, on travel speeds. Additionally, drivers demonstrated noticeable speed adjustments both when approaching and departing from posted speed limit signs. This study also explored driver speed selection at the entry of roundabouts in the presence and absence of pedestrians and bicyclists. Speed data were collected at 9 roundabouts in Minnesota using a combination of handheld lidar guns and video cameras. To capture driver yielding behavior, staged crossing events were conducted for pedestrians and bicyclists. The results showed differences in speed selection behavior based on whether a pedestrian or bicyclist was waiting to cross at the roundabout entry and the response of the driver to VRU presence. The study also recommended a minimum of 1.5 times the stopping sight distance (SSD) for the line of sight of the crosswalk and potential crossing points. Lastly, this study compared driver speed selection at the entry and exit approaches of roundabouts, signalized intersections, and all-way stop-controlled (AWSC) intersections across 20 locations. Roundabouts were found to be the most effective at reducing vehicle speeds at both the entry and exit approaches, reinforcing their effectiveness as a traffic calming measure compared to the other two intersection control types. Ultimately, this study will enable a more proactive and data-driven approach to highway design and speed management, helping transportation agencies achieve their goal of setting effective target speeds that reflect context, improve safety, and serve all road users.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
NEUTRAL-POINT-LESS MULTILEVEL INVERTER WITH A SINGLE DC-LINK CAPACITOR
No full textThesis (Ph.D.)--Michigan State University. Electrical Engineering - Doctor of Philosophy, 2025Multilevel inverters (MLIs) offer promising solutions for meeting the rising voltage requirements in electric transportation applications. Advances in MLI technology have enhanced power density, performance, and power ratings in inverter design. However, traditional MLIs have drawbacks of limited capability to operate in dynamic conditions, with low harmonics, low electromagnetic interference (EMI) and high-power density, without increased switch count, oversized DC-link capacitors to reduce voltage ripple, or increased complexity in modulation methods to balance capacitor voltages. A topological analysis led to the proposal of neutral-point-less (NPL) inverters, which address challenges in traditional MLIs by redesigning the topology to eliminate key sources of harmonics, voltage imbalances, and EMI.The operating principles of NPL.H and NPL.X inverters were introduced and compared with conventional MLIs using a duality approach. The findings showed that load impedance-based voltage division enables multilevel voltage generation without the stacked capacitors common in traditional MLIs. NPL inverters employ active neutral point generation rather than static capacitor-based neutral point, decoupling the neutral point current from the DC-link capacitor and inverter current. This approach reduces harmonics in the output voltage and current, along with ripple in the DC-link voltage and current. The NPL inverters also generates active common-mode voltage (CMV) cancellation to achieve a high level of common-mode electromagnetic interference (CM EMI) noise. The NPL inverters overcome the topological limitation of the conventional MLIs, which have a trade-off relationship between neutral current and CMV. The proposed NPL inverter topologies eliminate the neutral connection and generates two equal and opposite CMVs. These features enable a significant CM EMI noise reduction, through active CMV cancellation, while maintaining the neutral current at zero. Due to the elimination of the stacked capacitors, the source of imbalance within the inverter topology is fundamentally different from conventional capacitor-based MLIs. Since the NPL inverters rely solely on load impedance for voltage division, the voltage level imbalances are dependent on inductive dynamics, versus the capacitive dynamics found in conventional MLIs. The effect of an imbalanced load is explored via equivalent impedance in connected load networks, generating a simple scaling factor to calculate the achievable half voltage level with load imbalance. Imbalance in load can lead to voltage overshoot in the switching transition, which quickly settles to the half voltage level. Offset in achievable voltage levels are minimal, at approximately 5% of the DC-link voltage, with nominally imbalance. Additionally, the EMI noise reduction performance is highly dependent on the symmetricity of two equal and opposite CMV waveforms, which can be distorted under unbalanced load conditions. The influence of load imbalance on inverter operation and CMV cancellation is analyzed using incrementally increased imbalance in the load. Simulation and experimental results reveal that, while CMV cancellation is not perfect, the NPL.H inverter is still able to achieve a major reduction in CMV as compared to a conventional MLI without active cancellation. Various modulation methods can be utilized to improve DC-link capacitor voltage and current ripple. However, traditional MLIs require a neutral point connection with split capacitors which can cause capacitor voltage imbalance and overstress on devices due to the neutral current injection that can be made worse with various modulation methods. With the elimination of the capacitor-based neutral point, the effect of modulation methods on NPL inverters can be explored. A simple high order form algorithm analytically investigates DC-link capacitor voltage and current ripple in NPL inverters. The inverter was studied using two simple methods of carrier-based space vector pulse width modulation: phase opposition disposition (POD) and phase disposition (PD). PD modulation was consistently lower in DC-link capacitor rms and voltage ripple than POD modulation method at various operating conditions. Additionally, simpler carrier-based discontinuous pulse width modulation (DPWM) methods were re-evaluated for the NPL inverters. DPWM is advantageous in reducing switching transitions and power losses, but it increases DC-link voltage and current ripple due to the neutral point connection in conventional MLIs (e.g., T-type and NPC inverters). It was found that DPWM2 reduces harmonics and improves efficiency in NPL inverters by decreasing switching events, as validated through simulations and experiments.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Lesbian vs. Dyke : An examination of the differences in social meaning between two queer identity terms
No full textThesis (M.A.)--Michigan State University. Linguistics - Master of Arts, 2025This thesis constitutes a two-part, descriptive research study investigating perceived differences in indexical meaning between the identity terms lesbian and dyke for members of the L1 English-speaking LGBTQ+ community in the United States. The study tested the hypothesis that the meanings of lesbian and dyke have become more similar over time. Results from an initial survey eliciting free associations with the target words suggest that the primary zones of indexical difference between lesbian and dyke for this community are gender identity and expression of the referent. One of the association categories most commonly evoked by lesbian was \u2018woman/non-man,\u2019 while one of the association categories most commonly evoked by dyke was \u2018masculine/butch/gender non-conforming.\u2019 These indexical mappings and others were confirmed in a second survey, in which respondents rated the strength of association between a subset of elicited descriptors (including \u2018woman,\u2019 \u2018woman and/or nonbinary,\u2019 \u2018femininity,\u2019 and \u2018masculinity\u2019) and the identity terms lesbian and dyke. However, contrary to the above hypothesis, the youngest generation of participants were found to report the highest degree of difference between lesbian and dyke for many descriptors. This thesis serves as a model for future studies investigating the nuances of identity language and examines how the phenomenon of semantic change might be viewed through a sociolinguistic lens.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
EVALUATING OUTCOMES AND FIDELITY IN A TASK-BASED UNIVERSITY LANGUAGE PROGRAM
No full textThesis (Ph.D.)--Michigan State University. Second Language Studies - Doctor of Philosophy, 2025Language program evaluation offers a systematic, multi-methodological, stakeholder-sensitive, and use-focused approach to documenting both the pedagogy and outcomes in language programs (Norris, 2006, 2025). As an inherently programmatic and holistic proposal for additional language (L2) education, task-based language teaching (TBLT) offers a coherent model on which L2 curricula can (theoretically) be based and implemented and should theoretically offer a variety of robust desirable educational outcomes (Long, 2015). However, to date, there is a dearth of empirical evidence documenting the programmatic viability, implementation, or outcomes of TBLT programs (Boers & Faez, 2023; Norris & Davis, 2021). Against this backdrop, the present study adopted language program evaluation as a methodological framework to study the implementation of strong-form TBLT in a large, public, urban university Spanish language program in the United States. The study was designed based on questions of interest to local program stakeholders, namely: (1) to what extent the program was attaining its goal of implementing strong-form (i.e., Long, 2015) TBLT; (2) what L2 proficiency outcomes were being attained by the program; and (3) to what extent fidelity to strong-form TBLT differentiated L2 proficiency outcomes once learner background characteristics were accounted for. The study employed a mixed-methods approach including document analysis, observations, interviews, questionnaires, and standardized proficiency testing to answer these three questions. Based on findings from these three datasets, I present evidence that the evaluated program is implementing many components of strong-form TBLT and achieving robust levels of language proficiency development across heterogeneous learner backgrounds. I conclude by contextualizing the results from the present study in the ongoing project of TBLT scholarship to be a \u201cresearch-based pedagogy\u201d, evaluating the viability of TBLT, especially for the study of languages other than English in postsecondary contexts like the focal context of the present study, and identifying future directions for collaborative research at the intersection of language program evaluation and TBLT.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
EXAMINING THE IMPACT OF BENEVOLENT SEXISM ON ENGAGEMENT IN AND PERCEPTIONS OF ALLYSHIP BEHAVIORS
No full textThesis (M.A.)--Michigan State University. Psychology - Master of Arts, 2025Allyship has become an increasingly popular topic in both academic and non-academic settings, with some researchers exploring different manifestations of allyship. More specifically, various streams of research have begun to examine performative allyship, which refers to behaviors that center on the actor rather than on the targets of allyship, and how it contrasts with genuine allyship, which refers to actions intended to benefit members of oppressed groups. One perspective that may contextualize allyship attempts is benevolent sexism theory. Benevolent sexism encompasses superficially positive perceptions of women that ultimately reinforce existing gender hierarchies. Accordingly, the current research sought to determine the relationship between benevolent sexism and engagement in and perceptions of allyship. Two distinct studies were designed to examine whether 1) men\u2019s endorsement of benevolent sexism impacts their engagement in genuine and performative allyship behaviors toward a female colleague and 2) whether endorsement of benevolent sexism impacts evaluations of allyship attempts. Results of Study 1 indicated that endorsement of benevolent sexism was positively related to engaging in both genuine and performative allyship, and the dimensions of benevolent sexism were differentially related to both forms of allyship. Specifically, complementary gender differentiation was positively related to engaging in both genuine and performative allyship, whereas protective paternalism was only positively correlated with performative allyship. Results of Study 2, however, indicated that endorsement of benevolent sexism does not impact evaluations of allyship attempts. Themes from exploratory qualitative analyses suggested that there may be nuance to the motivations underlying allyship behaviors and a high degree of variance in how people evaluate allyship behaviors. Implications, limitations, and future directions for research on benevolent sexism and allyship are discussed.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references