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Echocardiographic Evaluation of Cardiac Structure, Function and Ventricular-Arterial Coupling of Adults with Down Syndrome
No full textBACKGROUND: This dissertation presents a comprehensive echocardiographic evaluation of cardiac structure, function, and ventricular-arterial coupling in adults with Down syndrome (Ds). Individuals with Down syndrome are living longer due to significant improvements in medical care and early surgical repair of congenital heart defects; however, cardiovascular disease remains a leading cause of mortality in this population. Despite this, detailed cardiac assessment of adults with Down syndrome without congenital heart defects remains underrepresented in cardiovascular research, with most existing literature focusing on pediatric populations or congenital anomalies.AIMS: The primary objective of this research was to compare cardiac structure, systolic and diastolic function, and ventricular-arterial coupling between adults with Down syndrome and age- and activity-matched adults without Down syndrome. METHODS: This study used a cross-sectional design including 40 adults with Down syndrome and 20 adults without Down syndrome, aged 18-35, with similar low physical activity levels. Comprehensive baseline echocardiographic examinations were performed by a certified Registered Diagnostic Cardiac Sonographer (RDCS) following the American Society of Echocardiography guidelines. Measurements were obtained using multiple echocardiographic views (parasternal long axis, parasternal short axis, apical four-chamber, apical two-chamber, and apical five-chamber) and various imaging modalities (2-D imaging, M-mode, Tissue Doppler Imaging, and Simpson\u27s biplane) to acquire a comprehensive assessment of cardiac dimensions, volumes, velocities, and functional parameters. RESULTS: The first study (Chapter 2) focused on cardiac size and systolic function, showing that adults with Down syndrome had significantly smaller left ventricular internal diameters during diastole (LVIDd) and systole (LVIDs), smaller left ventricular end-systolic volumes indexed to body surface area (LVESVI), and smaller left atrial dimensions (LAD) and volumes indexed to body surface area (LAVI) compared to adults without Down syndrome. In this study, adults with Down syndrome had lower diastolic blood pressure and lower stroke volume than adults without Down syndrome. Despite having smaller internal diameters and volumes, adults with Down syndrome demonstrated higher ejection fractions and fractional shortening, suggesting compensatory mechanisms that help maintain cardiac output. The second study (Chapter 3) examined diastolic function, demonstrating that adults with Down syndrome had significantly reduced lateral Tissue Doppler Imaging (TDI) of early diastolic myocardial velocity (Em), suggesting impaired myocardial relaxation during early diastole. Conversely, they exhibited higher mitral inflow velocity (eV), indicating a compensatory mechanism for rapid ventricular filling. These findings suggest altered diastolic mechanics characterized by reduced myocardial relaxation velocities and increased early filling velocities, reflecting a complex pattern of diastolic function. The third study (Chapter 4) provided novel insights into ventricular-arterial coupling (VAC) in adults with Down syndrome using the non-invasive single-beat method described by Chen et al. Adults with Down syndrome had significantly lower VAC ratios, faster pre-ejection times (PEP), and shorter normalized systolic durations (tNd) compared to adults without Down syndrome. These parameters suggest that in this study, adults with Down syndrome spent less time in systole, generated left ventricular pressure more rapidly, and exhibited a different balance between ventricular and arterial function than adults without Down syndrome. The findings of this dissertation reveal a unique cardiac phenotype in adults with Down syndrome characterized by smaller cardiac dimensions and volumes, compensatory systolic hyperfunction, altered diastolic mechanics, and a distinct ventricular-arterial coupling profile. These findings suggest that adults with Down syndrome maintained cardiac output at rest through several compensatory mechanisms: (1) higher ejection fraction and fractional shortening to maximize stroke volume from smaller ventricular dimensions, and volumes (2) increased early mitral inflow velocities to optimize diastolic filling despite reduced myocardial relaxation, and (3) rapid pressure generation during a shortened systolic period. Lower diastolic blood pressure in adults with Down syndrome may be an additional physiological factor that could impact cardiac function in this population. Lower diastolic blood pressure could decrease coronary perfusion during diastole and reduce preload due to diminished venous return, necessitating the compensatory mechanisms observed in this study. This challenges the traditional view that lower blood pressure is universally beneficial and suggests that lower diastolic blood pressure in adults with Down syndrome may contribute to a complex pattern of cardiovascular compensatory mechanisms. CONCLUSION: This dissertation provides several key contributions to the field. First, it challenges the conventional interpretation that a higher ejection fraction indicates superior cardiac function, demonstrating that a higher ejection fraction in adults with Down syndrome reflects a compensatory mechanism to maintain cardiac output despite smaller cardiac dimensions and volumes. Second, it showed that adults with Down syndrome had impaired myocardial relaxation partially offset by increased early filling velocities. Third, it provides the first comprehensive assessment of ventricular-arterial coupling in adults with Down syndrome. These findings potentially have clinical implications, and clinicians should consider a comprehensive evaluation of structural parameters, diastolic function, and ventricular-arterial coupling to assess cardiovascular health in adults with Down syndrome thoroughly. Future research should explore whether the cardiac compensatory mechanisms observed in this study evolve with aging and whether they contribute to the increased cardiovascular mortality seen in older adults with Down syndrome. Longitudinal studies incorporating advanced echocardiographic techniques, such as 3D imaging and strain analysis, would provide valuable insights into this population\u27s cardiac function. Additional investigation of the underlying mechanisms of increased cardiac contractility, including assessment of endothelial function and biomarkers of myocardial stress, would further enhance our understanding of cardiovascular physiology in adults with Down syndrome. In conclusion, this dissertation illustrates that adults with Down syndrome exhibited a distinct cardiac phenotype characterized by smaller cardiac dimensions and volumes, compensatory hypercontractile systolic function, altered diastolic mechanics, and less efficient ventricular-arterial coupling. These adaptations assist in maintaining cardiac output at rest but may lead to reduced cardiac reserve. This research establishes a foundation for improved cardiovascular assessment and care in this expanding adult population by providing a more nuanced understanding of cardiac function in adults with Down syndrome
Development and Validation of a Scale to Measure Viewer Experience in Guided Live Streaming Tours from Service-Dominant Logic and Customer-Dominant Logic Perspectives
No full textThis study develops and validates a scale to measure viewer experience in guided live streaming tours (GLST), a structured and professionally led format of live streaming distinct from user-generated content. Despite its rapid growth, GLST remains underexplored in theory and measurement. To address this gap, the study adopts an integrated lens of service-dominant logic (SDL) and customer-dominant logic (CDL) to conceptualize GLST as a multidimensional viewer experience.Scale development followed five phases. A literature review and in-depth interviews identified initial constructs. The expert panel review refined item content. A pilot study and exploratory factor analysis (EFA) revealed seven dimensions. Confirmatory factor analysis (CFA) compared four models: the Single-Factor Model (M1), the Second-Order Factor Model (M2), the Two-Factor Second-Order Model (M3), and the Seven Correlated First-Order Factors Model (M7). M1 was excluded due to poor fit and theoretical weakness. M2, M3, and M7 were tested in structural equation modeling (SEM). M2 showed the best overall fit and offered conceptual parsimony by capturing the GLST experience through an integrated SDL/CDL perspective. Therefore, M2 was selected as the final measurement model. The validated GLST scale comprises seven reliable and distinct dimensions: Interactivity, Informativeness, Functionality, Professional Competency, Practicality, Immersion, and Knowledge Acquisition. Nomological SEM analysis confirmed that GLST experience significantly predicts trust, which in turn mediates behavioral intentions, word-of-mouth, reuse, and visit intention. These results validate the theoretical framework and clarify how GLST design influences viewer trust and engagement. This study contributes a theory-based measurement tool tailored to guided live streaming, expanding virtual tourism research with SDL/CDL integration. It also provides practical guidance for improving professional live streaming sessions by emphasizing experience dimensions most critical to viewer trust and behavioral response
Leveling the Playing Field: the Power of Pre-class Structure in Inclusive Education
No full textMany students enter UNLV without prior instruction on effective learning strategies or class preparation, and their limited classroom contact hours further hinder the development of essential study and self-regulation skills. This challenge is particularly pronounced among students from underrepresented and underserved communities. To address this, I created structured pre-class activities designed to equip students with effective study habits and learning strategies that support their success both in and out of the classroom. Before each class session, students complete a “Pre-Class Guided Practice” handout, which includes an overview of the new material, clearly defined learning objectives, a QR code linking to short instructional YouTube videos I have created, targeted practice problems, and a reminder to complete a low-stakes pre-class Canvas quiz. These pre-class activities foster independent learning and skill development, allowing valuable class time to be dedicated to higher-level activities and more meaningful hands-on engagement rather than passive content delivery.https://oasis.library.unlv.edu/btp_expo/1212/thumbnail.jp
One-Page RPGs: An Engaging Alternative to Group PPTs
No full textLooking to increase student engagement and interest, I added the one-page RPG as an option my HON 110 students have for their group project. Ideally, student-designed games help them think more carefully about class readings and related contexts and connect meaningfully to that material in ways that make the Honors College’s second-year seminar a more memorable, transformative experience. These games also help students better understand a potentially unfamiliar genre. Finally, because materials are shared outside of class, there is a reduced stress level related to conventional, in-front-of-the-class, end-of-semester group presentations.https://oasis.library.unlv.edu/btp_expo/1220/thumbnail.jp
Sex Differences in Exercise and Sleep Among University Faculty and Staff Members
No full textTopics in Exercise Science and Kinesiology Volume 6: Issue 1, Article 4, 2025. There has been minimal research examining the exercise and sleeping patterns of university faculty and staff members and what role these factors play in overall health. The information gathered in this study was used to analyze how faculty and staff can adapt their behaviors to improve health and well-being. To explore sex differences in exercise and sleep in faculty and staff at a university in the Midwest, the study performed secondary analyses on data collected from the 2022 American College Health Association’s National Faculty and Staff Health Assessment. Independent t-tests, Chi-Square tests, and Mann-Whitney U tests were performed to analyze exercise and sleeping behaviors. In the 539 respondents included, sex differences were found regarding vigorous exercise, length of time to fall asleep, and the use of over-the-counter medication to promote sleep. Females reported fewer total minutes performing vigorous activity in the past seven days. Most females and males reported either six or seven hours of sleep per night. A greater proportion of females indicated taking 31 minutes or more to fall asleep compared to males, and a greater proportion of males indicated taking 5 minutes or less to fall asleep compared to females. Females were more likely than males to use over-the-counter medication to promote sleep. Further research is needed to determine the precise relationship between sex differences in exercise and sleep in faculty and staf
Case Study: Effect of Stroboscopic Vision Training During a Softball Season
No full textTopics in Exercise Science and Kinesiology Volume 6: Issue 1, Article 3, 2025. This case study examined the effects of stroboscopic vision training during an entire varsity softball season for a 16-year-old female. Stroboscopic vision training uses specialized glasses with crystallized fluid that flickers, intermittently impeding vision, a technique that enhances visual performance. The stroboscopic glasses were worn two to three times a week during hitting and fielding skills. The central hypothesis was that the stroboscopic vision training would enhance softball vision performance. The central hypothesis was tested using these specific aims: 1) batting statistics for a year with no stroboscopic versus a year with the stroboscopic vision training; and 2) vision-specific measurements for tracking, peripheral vision, and eye teaming. For the first aim, coaches recorded on-base percentage, batting average, slugging percentage, and hard-hit ball percentage. The second aim was tested by an ophthalmologist in a vision therapy center, with developmental eye movement, vergence ranges, randot stereopsis, and accommodative ranges measured. The innovative application in this study was combining on-field performance and vision testing using stroboscopic goggles. Data from batting statistics demonstrated a 136% increase in batting average and a 168% increase in slugging percentage. Post-test vision measurements increased base in/eyes relaxed by two diopters. Vision measurements demonstrated improved overall reaction time and peripheral fusion (peripheral vision). Limitations are present in the results due to single-subject case study design; follow-up studies with larger sample sizes and control groups to validate these findings are needed. Future research with a more rigorous experimental design will build upon this case study
Reassessing Policy Responses to Irregular Migration in Receiving Democracies: A Process-Tracing Analysis of Transactional Migration Governance
No full textThis policy brief analyzes the growing use of transactional migration agreements (TMAs) by receiving democracies—bilateral arrangements that exchange financial or diplomatic concessions for the external enforcement of migration control. While politically expedient, TMAs often generate long-term strategic liabilities: they reduce state control over enforcement outcomes, expose receiving states to coercive leverage by partner states, and weaken normative commitments to transparency and rights protection. Using analytic process tracing and formal modeling, this paper identifies four recurring mechanisms by which TMAs evolve into systems of asymmetric dependence. It then evaluates three alternative policy frameworks—Exit Doctrine, Legal Category Reform, and a Structured Conditionality Regime—against five criteria: policy durability, administrative implementability, normative capital preservation, responsiveness to structural drivers, and political feasibility. Among them, the Structured Conditionality Regime offers the most viable path forward: it aligns with current executive priorities by tying cooperation to measurable outcomes, limiting open-ended aid commitments, and restoring control over migration enforcement without requiring multilateral consensus
All Set for Next Week: Reorienting Domesticity, Gendered Labor, and Collective Mourning
No full textAll Set for Next Week (2024) was a coffin‐shaped coffee table that formed the focal point of my Honey, I’m Home! Midway Exhibition—a core requirement for my advancement to candidacy, which I successfully completed. Revisiting the nostalgic domestic imagery of mid‐twentieth‐century sitcoms like The Honeymooners and I Love Lucy, this piece examined the precarious nature of home, shifts in gender roles, and the collective reshaping of mourning rituals during the COVID‐19 pandemic. Made from red oak, a wood historically linked to coffin‐making, the table evoked the memory of my grandfather’s passing while probing deeper questions surrounding inherited skill sets and overlooked funerary traditions. Informed by Gaston Bachelard’s phenomenological perspective on the home and Mona Hadler’s ideas on “destruction as transformation,” All Set for Next Week (2024) questioned established notions of comfort and finality, inviting viewers to consider how memory, grief, and identity intersect within ordinary domestic spaces
Niche Conservatism and Sympatric Parallel Evolution May Help to Maintain Eight Nascent Tree Taxa Along a Sharp Elevation Gradient
No full textPatterns of niche partitioning among closely related taxa, such as those in incipient adaptive radiations, can provide clues into how niches are created, partitioned, and integrated over ecological and evolutionary time scales. Hawaiian Metrosideros is a ~3-MYO adaptive radiation of trees that dominates the Hawaiian Islands in continuous stands within islands and allows examination of niche partitioning at the early stages of adaptive radiation. We monitored growth and survivorship over 2 years of seedlings derived from open-pollinated fruits of eight Metrosideros taxa distributed along the elevation gradient of Koʻolau Volcano, Oʻahu, under four combinations of light and phosphorus. We included four glabrous taxa, representing mixed lineages and four pubescent taxa, representing a single, Oʻahu-endemic lineage and tested hypotheses of differentiation among taxa and between glabrous and pubescent groups. Variation among taxa in response to light and phosphorus was modest, with high-elevation taxa showing relatively greater niche partitioning (per Pianka\u27s Index). Patterns of growth rate variation (plasticity) along the elevation gradient in response to light and phosphorus were similar between the glabrous and pubescent groups, with low-elevation taxa showing high and low plasticity to light and phosphorus, respectively. Patterns of survivorship across light and phosphorus treatments were highly concordant within the recently evolved pubescent lineage. Both growth rates and survivorship rates suggested the conservation of contrasting light niches within glabrous and pubescent groups. Finally, the retention of taxon-diagnostic phenotypes despite 2 years of growth under contrasting environments implied significant heritable differentiation among the eight taxa, despite the likely presence of hybrids in the open-pollinated seedlings. The coexistence of eight predominantly infraspecific tree taxa within the confines of Metrosideros forest on Koʻolau Volcano appears to result from a combination of niche conservatism within the glabrous and pubescent groups and sympatric parallel evolution between these groups along elevation gradients. The modest niche partitioning among taxa by light and phosphorus, especially at middle elevations, suggests that additional environmental factors contribute to local adaptation in these trees. Results of this study suggest that both stabilizing and diversifying processes contribute to the early stages of adaptive radiation in trees
Chronic Student Absenteeism in the Mountain West, 2018-2023
No full textThis fact sheet examines data on chronic student absenteeism rates across five Mountain West states: Arizona, Colorado, Utah, New Mexico, and Nevada. The “Tracking State Trends in Chronic Absenteeism” report by FutureEd, an education policy think tank at Georgetown University, provides data for 42 states and the District of Columbia for the school years of 2018-2019, 2021-2022, and 2022-2023