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Curvature and sharp growth rates of log-quasimodes on compact manifolds
Get PDFWe obtain new optimal estimates for the L2(M)→Lq(M), q∈(2,qc], qc=2(n+1)/(n−1), operator norms of spectral projection operators associated with spectral windows [λ,λ+δ(λ)], with δ(λ)=O((logλ)−1) on compact Riemannian manifolds (M,g) of dimension n≥2 all of whose sectional curvatures are nonpositive or negative. We show that these two different types of estimates are saturated on flat manifolds or manifolds all of whose sectional curvatures are negative. This allows us to classify compact space forms in terms of the size of Lq-norms of quasimodes for each Lebesgue exponent q∈(2,qc], even though it is impossible to distinguish between ones of negative or zero curvature sectional curvature for any q\u3eqc
Weak maps and the Tutte polynomial
No full textLet M and N be matroids such that N is the image of M under a rank-preserving weak map. Generalizing results of Lucas, we prove that, for x and y positive, T(M;x,y)≥T(N;x,y) if and only if x+y≥xy or M≅N. We give a number of consequences of this result
Orthorexia Nervosa\u27s Factor Structure: Relationships with Transdiagnostic Eating Disorder Symptoms, Impairment, and Gender
No full textOrthorexia Nervosa (ON) is a condition characterized by rigidity around the quality of one’s food consumption. While ON is not included in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR), a large proportion of professionals who treat eating disorders (EDs) report having observed this phenomenon in their clinical practice (Vandereycken, 2011). Despite this, many existing measures of ON have demonstrated poor psychometric properties, which likely impact the ability of clinicians to identify and treat those with ON. One recently developed measure, the Orthorexia Nervosa Inventory (ONI), appears promising. The present study sought to confirm the 3-factor structure of the ONI demonstrated by Oberle et al. (2021) during its development, while also assessing the relationship between ON symptoms, transdiagnostic ED symptoms, gender, and impairment. Consistent with prior studies, factor analysis yielded three factors in the present study: Impairment, Behavior, and Emotion-Cognition (Kaya et al., 2022; Oberle et al., 2021; Zagaria et al., 2023). Examination of Tucker’s congruence coefficients showed that women and men demonstrated fair similarity on the Impairment and Behavior factors, though this was not the case for the Emotion-Cognition factor, suggesting that the Emotion-Cognition factor did not measure the same construct among men and women. Lastly, results of this study demonstrated that both transdiagnostic ED symptoms and respective ON factors appeared to be equally predictive of the Emotion-Cognition factor, but that respective ON factors accounted for significantly more variance in the Impairment and Behavior factors compared to ED symptoms. Furthermore, one specific ED symptom (i.e., body checking) was a partial mediator in the relationship between ON-related Emotion-Cognition and ON-related Impairment, suggesting that ED symptoms may indirectly affect impairment associated with ON. Taken together, the results of this study demonstrate that ON is a multi-faceted construct that is experienced differently based on gender and is predicted by transdiagnostic eating disorder symptoms. Further research is needed in these areas, particularly regarding symptom presentation among men
The Oboe Thread: Tracing The Evolution of Viet Cuong\u27s Compositional Voice
Get PDFViet Cuong is an emerging and highly regarded American composer currently serving on the faculty at the University of Nevada, Las Vegas, where he teaches composition, orchestration, and music theory. Cuong\u27s academic credentials include degrees from prestigious institutions such as the Curtis Institute of Music, Princeton University, and the Peabody Conservatory of Music. Over the years, his compositional portfolio has expanded significantly, encompassing a diverse range of genres and mediums, including vocal, orchestral, wind band, and chamber music. His chamber works, in particular, stand out for their fusion of diverse genres and instrumentation. One area in which Cuong has made notable contributions is his exploration of the oboe. His affinity for the oboe has resulted in an impressive body of work that provides a rich and varied repertoire for oboe performers, which will be a central focus of this final project.
This project will examine three chamber works by Cuong: Suite for Two Oboes and English Horn, Extra Fancy for Two Oboes, English Horn, and Two Bassoons, and Circling Back for Oboe and Cello. These pieces mark important stages in Cuong’s compositional development, each showcasing different aspects of his musical style and his expanding exploration of the oboe as an expressive instrument. Covering a variety of genres and musical contexts, these works highlight Cuong\u27s versatility and his ability to combine technical innovation with emotional expression. The project will include a detailed analysis of selected parts from these compositions, comparing them to other prominent works in the oboe repertoire to emphasize their distinctive contributions
BE Mindful: Examining a Brief Mindfulness Intervention on Educator Well-being
Get PDFTeaching is currently rated as one of the topmost stressful occupations. Concerningly, chronic levels of stress can lead to poor mental and physical health, occupational burnout, and teacher attrition; all of which have a negative impact on student outcomes. Mindfulness-based interventions (MBIs) are commonly used to combat occupational stress by enhancing educator well-being. There is compelling evidence to support these types of interventions with teachers. However, the length of many MBIs may make them prohibitive for the average educator to participate in them. The literature suggests that a briefer format may be just as effective at reducing stress, but more research needs to be done specifically with this population. Thus, the current study adapted a brief two-week MBI and tailored it toward in-service educators. By using a randomized controlled trial with a wait-list control, the present study examined the effectiveness of this brief educator mindfulness (i.e., B.E. Mindful) intervention on its ability to improve educator well-being through the reduction of stress and burnout. The results demonstrated significant improvements in positive affect and reductions in stress compared to the control. The findings of this study offer initial support for a more time- and resource-efficient and, therefore, more scalable approach to the prevention and management of teacher stress
The Effect of Errors of Lexical Stress on Word Repetition Accuracy Among Monolingual and Bilingual Listeners
No full textMany of the world’s languages manipulate duration, fundamental frequency, and intensity at the syllable level (i.e., lexical stress) to achieve relative prominence of one syllable over others in a word. Variable-stress languages—languages in which this manipulation is used contrastively (i.e., stress minimal pairs such as TRUsty vs. trusTEE)—differ in the relative importance of lexical stress for spoken word recognition. These cross-linguistic differences in the importance of lexical stress result from the relative distribution of stress minimal pairs as well as whether vowel reduction co-occurs with unstressed syllables. It has been argued that lexical stress plays an equally important role as phonemes in spoken word recognition for speakers of some variable-stress languages such as Spanish. However, commonly cited models of spoken word recognition—which are based primarily on monolingual English listeners about whom research has presented conflicting evidence on the importance of lexical stress—fail to mention lexical stress altogether. This omission has led many researchers to call for revisions to models of spoken word recognition. Missing from the discussion has been the experience of bilingual listeners of variable-stress languages.
In the present study, I investigated the faciliatory effect of lexical stress for spoken word recognition among bilingual Spanish-English listeners (N = 48) and monolingual English listeners (N = 41). This study involved a verbal shadowing task to ascertain the impact of errors of lexical stress on spoken word recognition. Results from this study challenge the exclusion of lexical stress from models of spoken word recognition. Although between-group differences were noted, participants from both language groups were significantly more likely to respond accurately to stimuli with correct stress. It would be difficult to explain the present findings without reference to lexical stress as a facilitator of spoken word recognition. The present findings suggest that lexical stress is an important cue to word identity for bilingual Spanish-English and monolingual English listeners. Thus, model revisions are warranted
FIRST-PRINCIPLES SIMULATIONS OF X-RAY PROBED ATTOSECOND ELECTRON DYNAMICS IN MOLECULES AND SOLIDS
No full textThis dissertation presents the results for two simulation studies of time-resolved attosecond spectroscopy using first principles with real-time time-dependent density func- tional theory (RT-TDDFT). These simulations are motivated by the new development of attosecond pulses at X-ray free electron laser facilities. The first project details the use of high energy pulses (extreme-UV/X-rays) to probe the strong-field near-infrared (NIR) induced attosecond transient metallization of dielectrics. Bulk mimicking finite clusters are used with transient absorption spectroscopy (TAS) to simulate the core-level spec- troscopy of the dielectrics silica and diamond. Our calculated Si L-edge TAS for silica compares well to the experimental study. We then analyze the C K-edge of diamond, a dielectric whose attosecond response has yet to be studied, with X-rays. Our results cap- ture the periodicity of optical density reduction in silica, and a similar response in the diamond K-edge. The second study involves probing electronic motion in the molecule 4-chlorocinnamaldehyde using X-rays in a ω/2ω pump/probe scheme. These dynamics are initiated via ionization of the Cl 2p electron (∼ 260 eV) which then causes electronic motion in the valence shell. This movement can then be observed via probing changes in the O K-edge features (∼ 520 eV). Our simulations determine through analysis of electron density and oscillations in the brightest feature of the TAS that electronic motion occurs across the molecule at a period of roughly 1 fs
The Design and Effect of Continuum Robot Compliance on Locomotion
Get PDFContinuum robots, due to their compliant structures and ability to navigate through constrained environments, offer significant advantages in applications requiring safe physical interaction and dexterous motion. However, challenges related to limited structural stiffness, payload capacity, and precise control remain open problems in the field. This dissertation presents novel contributions aimed at addressing these limitations through two main actuation units of continuum robots: tendon-driven continuum robots (TDCRs) and concentric tube robots (CTRs). In the first part, we focus on methods to improve the stability and modify the stiffness of the TDCR. A tendon decoupling strategy is introduced for planar TDCRs. The method is mathematically modeled, validated through kinematic simulations, and confirmed via experimental characterization. Additional investigations into alternative tendon routings, including helical and spiral paths, demonstrate improved stiffness profiles. A linearly adjustable nonlinear compliance mechanism, inspired by Hertzian contact theory, is integrated into the stiffening cables to enable continuous output stiffness adjustment without the need for an active control loop. For example, via implementing this methodology on a prototype robot, the stiffening cables and adjustable stiffness mechanism allow for the stiffness to be adjusted between a range of 6x to 11x of the stiffness in the corresponding case of only actuating cables (the most common tendon routing in literature). Inclusion of a stiffening cable of a higher-order mode showed a reduced effect, allowing for stiffnesses in the range of 1.5x to 2.2x of the stiffness in the case of only actuating cables. The stiffening tendon routing approach is further extended to three-dimensional spatial configurations, supported by simulations, the results confirm a strongly decoupled tendon length change for some of the purposed tendon routing. A new structural design in which the central backbone is replaced with a radially offset support to allow uninterrupted tendon routing while maintaining desired strain limits. The second part focuses on the development of a long concentric tube robot for industrial integrity assessments and applications. A grounded robotic platform capable of actuating tubes up to 102 cm in length is designed and tested, incorporating a novel contact-based locomotion strategy to improve navigation in complex environments. Frictional interactions with the environment are characterized qualitatively to determine operational thresholds. Lastly, a hand-held version of the CTR robot with coiled tubing configuration is developed, featuring custom actuation and control units, achieving an insertion length of 85 cm
FUNCTIONAL ROLE OF MYH9 IN CARDIAC REPAIR AFTER HEART INJURY
No full textCardiac myofibroblasts (CMFs) are specialized cardiac fibroblasts (CFs) expressing abundant actin stress fiber. However, the role of CMF contraction in post-myocardial infarction (MI) cardiac repair have not been defined yet. Here, we generated cardiac fibroblast–specific deletion of Myh9 to uncovers the pivotal role of non‑muscle myosin IIA in regulating fibroblast behavior in cultured condition and during myocardial repair. We found that Myh9 knockout (KO) significantly affected CMF morphology, completely abolished the stress fiber formation and contraction, and reduced their proliferation and motility. Mice lacking Myh9 in CFs have an increased post-MI cardiac rupture rate and reduced stress fiber formation, collagen deposition, fibrosis and systolic function. Transcriptomic, epigenetic, and proteomics analyses revealed disrupted expression of stress fiber and mesenchymal identity genes/proteins caused by Myh9 KO. Pharmacologic manipulation of RhoA and yes-associated protein (YAP) activity partially restored the differentiation of CMFs caused by Myh9 loss in vitro, highlighting a compensatory axis. Mechanistically, Myh9 KO led to an increased globular to filamentous actin (G/F-actin) ratio, decreased MRTFA activity, and altered epigenetic modification, which all contributed to trigger multiple consequences observed in cultured cells and mice lacking Myh9, demonstrating the indispensable role of Myh9 in maintaining normal CMF activity and promoting post-injury heart healing
Investigating Molecular Adsorption and Transport at Colloidal and Biological Interfaces Using Second Harmonic Generation Spectroscopy
No full textColloidal interfaces play a critical role in drug delivery, environmental sensing, and nanomedicine, yet quantifying molecular interactions at these surfaces remains experimentally challenging. This dissertation uses second harmonic generation (SHG) and extinction spectroscopy to investigate the adsorption and transport behavior of charged molecules at the colloidal interface in aqueous environments, including polystyrene sulfate (PSS) microparticles (MPs), phospholipid liposomes, and live bacterial membranes. The adsorption of the cationic dye malachite green (MG) to PSS microparticles was studied across a range of pH conditions, with enhanced interfacial binding observed under acidic conditions and diminished adsorption at higher pH values due to altered electrostatic attraction and dye degradation. SHG adsorption isotherms were modeled using a modified Langmuir approach, yielding equilibrium constants, surface site densities, and free energies of adsorption. Extinction corrections and microparticle depletion models were applied to account for absorption and scattering at both the fundamental and second harmonic wavelengths. A separate microparticle dilution correction is introduced to account for changes in available surface area resulting from the addition of MG solution volume. Additionally, time-resolved SHG was applied to probe MG transport across the outer and cytoplasmic membranes of Pseudomonas aeruginosa bacteria in aqueous suspension. Numerical modeling using Euler’s method provided estimates of transport rates and supported a two-membrane system model. Overall, this work demonstrates a surface-specific method for probing adsorption and transport processes at colloidal interfaces. The combined use of SHG and extinction spectroscopy techniques provide new insights into interfacial thermodynamics, molecular permeability, and experimental strategies for future studies in surface chemistry, membrane biophysics, and nanomaterial-based drug delivery systems