Local Measurement of Terahertz Field-Induced Second Harmonic Generation in Plasma Filaments and Single-Shot Detection of THz Using Third-Order Nonlinearities

Garriga Francis, Kareem J University of Rochester ProQuest Dissertations & T 2023 해외박사(DDOD)

In recent years, there has been considerable growth in laser development toward femtosecond pulsed high-energy systems. In conjunction, as the optical sources become improved, the opportunity for pulsed terahertz (THz) sources become wider still. Considering the current landscape of THz sources available, the advent of stronger and shorter-pulsed lasers hints at a bright future for THz technologies. For example, high peak electric field and broad-spectrum THz waves have many applications in nonlinear electromagnetic wave and material interaction as well as in wake-field acceleration of electrons. Unfortunately, although the development of THz sources can evolve in conjunction with optical sources, there is a natural plateau to the detectors of THz radiation. As the optical pump sources increase in output energy, there is an ever-growing need for single-shot and broad-bandwidth detection. In this thesis, the concept of Terahertz Field-Induced Second Harmonic (TFISH) Generation is revisited to introduce a single-shot detection scheme based on third order nonlinearities. Although the current THz landscape includes single-shot spectroscopy tools such as grating spectrometers and electro-optic sampling, temporal dynamics and unimpeded spectral characterization cannot be achieved simultaneously. The TFISH detection system has the advantage of providing sensitive temporal information, broad spectral characterization not limited by phonon resonances in crystals, and coherent pulse reconstruction through mixing with a local oscillator. Focused specifically on the further development of THz plasma-based sources such as air, liquid, and metal plasma, we begin our research by reimagining the TFISH system to serve as a direct plasma diagnostic. In this work, an optical probe beam is used to mix directly with the strong ponderomotive current associated with laser-induced ionization. A four-wave mixing (FWM) process then generates a strong second-harmonic optical wave because of the mixing of the probe beam with the nonlinear current components oscillating at THz frequencies. The observed conversion efficiency is high enough that for the first time, the TFISH signal appears visible to the human eye. We perform spectral, spatial, and temporal analysis on the detected second-harmonic frequency and show its direct relationship to the nonlinear current. Further, because of the high probe to TFISH conversion efficiency, a method to detect incoherent and coherent THz inside plasma filaments is devised using spatio-temporal couplings. The single-shot detection configurations are theoretically described using a combination of expanded FWM models with Kostenbauder and Gaussian Q-matrices. We show that the retrieved temporal traces for THz radiation from single and two-color laser-induced air-plasma sources match theoretical descriptions very well. High temporal resolution is shown with a detection bandwidth limited only by the spatial extent of the probe laser beam. Large detection bandwidth and temporal characterization is shown for THz radiation confined to under-dense plasma filaments induced by < 100 fs lasers below the relativistic intensity limit.

"Strange and Inexplicable": Musical Shape in Karlheinz Stockhausen's Gesang Der Junglinge

Brodack, Cory University of Rochester ProQuest Dissertations & T 2024 해외박사(DDOD)

Several scholars such as Schaeffer (1966), Chion (1983), Bregman (1990), and Godoy (1997, 2017) have written about the importance of perceiving musical gesture and shape in understanding music as a listener, but some such as Wishart (1996) have rightfully illustrated the potential downfalls of trying to formalize a codex of morphological shapes for this purpose. In the realm of acoustic music, tools have been developed to deal with shape and gesture in a formalized way, but when pitch and pitch-direction start to become obscured in denser and noisier textures such as those found prominently in electroacoustic music, a different way of listening to shape and analyzing the listening experience is needed. My approach focuses on describing the listening experience through musical content and shape using spectromorphology, a tool created by Denis Smalley (1997) for this purpose. While this method can describe a possible perceptual experience for a listener, it is also a compositional tool and listening aid, which is supported using "diffusion scores" and similar verbal and visual metaphors to represent different structural levels, functions, and processes in the music. I argue this is a useful approach for describing the listening experience of Gesang der Junglinge. In this dissertation, I approach Gesang der Junglinge using the tools developed by Denis Smalley, focusing on the overall time and spectral features of sound-shapes. I base this work on gestural features of the music, continuing the work of Schaeffer (1966), Bregman (1990), Huron (2006), and Smalley (1997).

Exploring Mechanobiology Within the Extracellular Microenvironment of the Impinged Achilles Tendon Insertion

Wise, Brian Charles University of Rochester ProQuest Dissertations & T 2026 해외박사(DDOD)

The composition and structure of the extracellular matrix (ECM) is crucial to the primary mechanical function of tendon, with fibrillar collagen aligned longitudinally to transmit tensile force generated by muscle to bone. A multitude of tendons, however, experience bony impingement due to normal anatomical positioning, which produces a multiaxial, spatially heterogeneous mechanical strain environment with significantly elevated transverse compressive strain. In impinged regions, tendon exhibits a distinct fibrocartilage phenotype discernible by unaligned fibrillar collagen matrix enriched with glycosaminoglycans (GAGs) via aggrecan, a large, GAG-rich proteoglycan. Appreciated as a normal adaptation to mechanical impingement, these same features are clinically recognized as hallmarks of tendinopathy, a common degenerative tendon disease that frequently emerges with chronic impingement. These phenotypic landmarks, however, insufficiently capture the biochemical spectrum of aggrecan in fibrocartilage, which contains a landscape of aggrecan fragments due to constitutive aggrecanase catabolism. This biochemical profile is distinct from that of tensile tendon, suggesting aggrecan turnover may govern ECM mechanics and may itself be regulated by mechanical environment. To test this concept, the overall objective of this thesis was to determine if mechanical impingement modulates the biochemical profile of aggrecan and ECM mechanical properties in association with fibrocartilage formation. In the absence of suitable experimental models, we developed and characterized a novel murine hind limb explant model for studying the mechanobiology of fibrocartilage formation at the Achilles tendon insertion in situ through controlled prescription of impingement via passive ankle dorsiflexion. We also designed a rigid boot to restrict the ankle of mice to a dorsiflexed position to interrogate fibrocartilage mechanobiology at the impinged Achilles tendon insertion in vivo. We performed immunofluorescence to capture biochemical change in aggrecan composition secondary to impingement and atomic force microscopy (AFM) for spatially-guided nanomechanical characterization of the ECM. Our results indicated that impingement elicits distinct biochemical profiles in aggrecan composition and significantly augments ECM indentation modulus in situ. These findings are significant because they elucidate the molecular foundations of mechanobiology in tendon fibrocartilage, which will ultimately enhance our understanding of, and ability to diagnose and treat, impingement-associated tendinopathies.

Why Modern Band?: A Multiple Case Study of Three Secondary General Music Teachers

Sanguinetti, Rachael D University of Rochester ProQuest Dissertations & T 2026 해외박사(DDOD)

General music programs are a common part of secondary music curricular offerings, but many scholars have noted the disconnect between the music usually taught in the classroom (Western classical music) and the music many students enjoy outside the classroom (popular music). Modern band is a facet of music education defined by its use of popular music, popular music instruments, and student-centered teaching approaches. Teachers’ use of modern band has rapidly expanded across the United States in secondary general music spaces since the introduction of modern band in 2008. Despite its rapid growth, there are few empirical studies on why teachers make the curricular shift to including modern band in their music programs. The purpose of this study was to explore why secondary general music teachers use modern band in their secondary general music classes. Research questions included (a) why do teachers use modern band in their secondary general music classes, (b) what preparation and professional development do teachers participate in to include modern band in their secondary general music classes, and (c) what challenges and barriers do teachers face in using modern band in their secondary general music classes? To answer the research questions, I used a multiple case study design and recruited three secondary general music teachers as participants. Data were collected via interviews and observations and included transcripts, field notes, artifacts, and a researcher journal. Data were analyzed using two levels of coding. Findings indicate that teachers use modern band in secondary general music because they believe it helps to (a) cultivate connections through shared popular music, (b) build student musicianship skills, and (c) prepare students for music after high school. Teachers lack modern band in their preservice teacher programs but engage in PD with Music Will, through connections with their communities, and through self-directed and independent learning. Challenges and barriers to the use of modern band include teacher time and exhaustion. Future research could explore these themes across a broader audience or investigate the ways modern band students experience connection to their teachers through shared popular music or how students engage with popular music after high school.

Measurement of the Weak Mixing Angle at 13 TeV With the CMS Detector

Taus, Rhys University of Rochester ProQuest Dissertations & T 2026 해외박사(DDOD)

This document summarizes work in experimental high-energy physics completed as part of the author’s doctoral studies. The central piece of this thesis is the precision measurement of the effective weak mixing angle at the CMS detector. The effective weak mixing angle is a key parameter in the standard model of particle physics and is sensitive to radiative corrections from beyond standard model physics. The measurement is made by using the forward backwards asymmetry of Drell-Yan dilepton pairs. The data is from proton proton collisions at √s =13 TeV collected in Run 2 of the LHC from 2016-2018. The measurement uses dimuon and dielectron pairs and includes a special class of forward electrons developed for this measurement that do not rely on the tracking subdetector. Using the CT18Z parton distribution function set the weak mixing angle was determined to besin2θℓeff = 0.23157 ± 0.00031The largest contribution to the uncertainty comes from the parton distribution functions.

Early Life Persistent Organic Pollutant Exposure, BMI, and Thyroid Hormone Levels in a Slovak Cohort

Kahwaji, Mariah University of Rochester ProQuest Dissertations & T 2026 해외박사(DDOD)

Persistent organic pollutants (POPs) are chemically stable organic substances that are ubiquitous in the environment and bioaccumulate in humans. POP exposure during early life disrupts normal development and epigenetic processes that are regulated by hormones and growth factors, leading to programming of non-communicable diseases. This dissertation assessed the association between early life exposure to persistent organic pollutants and thyroid hormone levels and body mass index at numerous time points during the pediatric period in the Slovak cohort. PCB-118, PCB-153, DDT, DDE, β-HCH, and HCB were measured in maternal, cord, 6-, 16-, 45-, 72-month and 10- and 20-year serum. Previously validated physiologically-based pharmacokinetic (PBPK) models were used to estimate average prenatal, average postnatal, and peak exposure to each POP up to age 45 months. In Aim 1, the association of early life exposure to POPs on longitudinal thyroid hormone levels during childhood (ages 45 months, 72 months, and 10-12 years) were estimated using generalized additive mixed effects modelling. Thyroid hormone levels were further studied in Aim 2 by Bayesian Weighted Quantile Sums Regression and Bayesian Kernel Machine Regression to estimate the overall mixture effect of POPs on thyroid hormone levels. In Aim 3, the association between early life exposure to mixtures of POPs and body mass index from age 45 months to early adulthood was estimated using Bayesian Weighted Quantile Sum regression with a mixed effects model framework. The association between early life exposure to single pollutant POPs and the monthly change in BMI-for-age z-scores up to age 19 months was estimated using mixed effects modeling. Early life exposure to POPs, both measured in serum and estimated by PBPK models were associated with lower fT3 levels, higher fT4 levels, and increased odds of T4 levels above the 90th percentile at ages 45 months, 72 months, and 10-12 years. Exposure to single pollutant POPs, but not mixtures, measured in maternal serum and the estimated average prenatal exposures were associated with increases in BMI-for-age z-scores up to age 19 months and repeated measures of BMI z-scores at four study visits across childhood and adolescence.

Blues and Bobby Sox: Singing Black Girlhood in New York City, 1950-1970

St. Amand, Emmalouise University of Rochester ProQuest Dissertations & T 2024 해외박사(DDOD)

This dissertation examines the musical and social lives of Black teenage girl singers in 1950s and 1960s New York City. During this time, Black girls were celebrated performers in local Black music scenes, but their legal minority left them vulnerable to exploitation from both sides of the color line. I combine interviews with former girl group performers and evidence from 45rpm records, gossip columns, school yearbooks, and more to chart girls' professional networks and listen closely to their recorded voices. Looking beyond the famous girl groups who recorded in New York City's pop music factories, I center every day, working musicians. I demonstrate that Black girls were active members of New York's Black music scene, where they wrote and recorded original songs, wrote music criticism, and contributed to public discourses about music and sexuality. Ultimately, I argue that understanding girl's music requires reshaping theories of power and agency that rely on an assumption of legal adulthood.After an introduction that lays out the major themes and methodological orientation, Chapter One examines the scattered archive of a forgotten girl group called the Four Debs to show that girls belong to a tradition of Black music-making, despite their failure to conform to scholarly ideas of "authentic" Black sound. The second chapter concerns child performer Annette Swinson, who gained professional opportunities by continually transforming her vocal timbre. I suggest that tracing Swinson's plastic voice offers one method for recovering girls' musical agency within a system that did not recognize them as full subjects. Chapter three maps girls' interest in romance through a musical pleasure culture that comprised songwriting, music criticism, and listening practices. I show that girls' pleasure culture provided a fantasy realm through which girls imagined themselves outside the control of adults. Finally, the fourth chapter analyzes the work of groups like the Shockley Singers, who were successful both as gospel performers and as pop recording artists. I argue that girls challenge racialized categorizations of sound at midcentury. Throughout the dissertation, I demonstrate the alternative histories that emerge when we center the working musicians that create the everyday texture of musical life.

Impacts of Cochlear Synaptopathy on Temporal Dynamics of Auditory Neural Responses in the Budgerigar

Wang, Yingxuan University of Rochester ProQuest Dissertations & T 2026 해외박사(DDOD)

Loss of synapses between the inner hair cell and auditory-nerve (AN) fibers, called cochlear synaptopathy, is a common health problem associated with aging and overexposure to loud sound. Cochlear synaptopathy is widely expected to cause hearing difficulties, while mixed evidence has been found. The budgerigar, a speech-mimicking parakeet species with sensitive low-frequency hearing and human-like auditory perception, is well-suited for auditory study given similar neuroarchitecture between birds and mammals.Cochlear synaptopathy may alter neural temporal dynamics (i.e. neural adaptation) along the ascending pathway, potentially leading to perceptual hearing difficulties in complex listening environments. To test this hypothesis, we used intracochlear injection of a glutamate analog, kainic acid (KA), to induce selective damage of AN fibers. The KA-induced AN damage was validated histologically and physiologically, and the hair cell epithelium was demonstrated to remain unaffected. A novel stimulus paradigm, the Poisson click train, was developed for fast assessment of neural adaptation. Adaptation at different processing stages along the ascending pathway was estimated using waves of the auditory brainstem response (ABR) generated by AN, midbrain and auditory cortex, then compared within individual animals before and after KA-exposure. Following cochlear synaptopathy, response patterns associated with stronger neural adaptation were found at conversational levels (65 dB SPL) in the AN. The midbrain-level waves had longer latency and more pronounced changes in adaptation than AN fibers, potentially due to cascading effects of cochlear synaptopathy. To further understand the perceptual consequences related to altered temporal dynamics, we examined the midbrain neural cues underlying behavioral detection of tone-in-noise stimuli with different temporal features in control animals. Neural responses from the auditory midbrain were recorded in awake budgerigars, and the neural thresholds were compared to behavioral thresholds obtained by operant conditioning tests. Specifically for transient signals in noise, behavioral detection was found to be correlated with the temporal profile of midbrain neural responses. Our findings demonstrate that cochlear synaptopathy alters the temporal dynamics of neural responses along the ascending auditory pathway. This alteration likely impacts neural processing of transient communication signals and might contribute to degraded real-world hearing abilities in people with cochlear synaptopathy.

Charting the Tides of Carolina Beach Music and the Shag

McArthur, Mary Gorman University of Rochester ProQuest Dissertations & T 2024 해외박사(DDOD)

For many, the term "beach music" evokes the vocal harmonies of the Beach Boys; however, Carolina beach music shares little in common with the surf music of California. Products of the segregated landscape of the Carolina coast, beach music and an associated dance called the shag emerged as white teenagers ventured into Black jook joints, transporting "race records" and swing-style dance steps to white beach pavilions. Despite their cultural significance and elevated legal status as official state symbols of South Carolina, both beach music and the shag remain largely unheard of outside the Southeast. There have been no critical histories of beach music and the shag or systematic attempts to analyze their stylistic conventions or social value. Drawing on interviews with members of the beach music and shag community and scholarship on popular music, identity, and cultural exchange, I argue that beach music and the shag serve as crucial sites for the negotiation of cultural identities tied to region, race, generation, and place. In my first two chapters, I trace the history of beach music and the shag from their origins in the 1940s to the present, examining their development in dialogue with the social, cultural, and ecological landscapes of the Carolina coast. In my third chapter, I analyze the extent to which beach music can be appropriately defined as a genre. Using Franco Fabbri's five genre rules as a framework, I analyze beach music and the shag to delineate the genre conventions that underlie the coherence and organization of the scene. In my fourth chapter, I theorize beach music and the shag as the foundation of a regional lifestyle, a communal practice of identity formation that enables participants to actively construct both self and space. Finally, I conclude with an epilogue describing the present concerns and future hopes of the beach music and shag scene. Ultimately, this dissertation contributes the first substantive study of beach music and the shag to the field of musicology, while also offering new perspectives on cultural history, southern heritage, and the processes through which music and movement construct space.

The Past, Present, and Future of Copyright Law's Musical Work: A View From Music Theory

Wilson, Lauren University of Rochester ProQuest Dissertations & T 2023 해외박사(DDOD)

This dissertation examines the relationship music theory can play and has played in American music copyright theory and litigation. Through the lens of copyright law’s “musical work,” I analyze how copyright laws have drifted in and out of alignment with the ways that contemporary theorists and musicians understand music. By exploring copyright’s history through a music-theoretical, technological, and cultural perspective, I argue that lawmakers’ attempts to understand and react to new musical developments have not kept pace with contemporary popular music. I then turn to the current state of music copyright litigation to problematize the current system of musical ownership that copyright law supports. A system of common property, which keeps the commonplace segments of music at issue in many copyright suits in the public domain, will best reflect the compositional processes known to the musicians governed by copyright laws. Finally, I offer a vision for the future of copyright law’s musical work that brings the law’s understanding of musical creativity into alignment with the priorities and practices of contemporary popular music.