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Maximum Overdrive: a Frequency Response Analysis of Distortion Due to Clipping
No full texthttps://rdc.reed.edu/v1/resources/41c9d955-ce59-4d80-893d-cc62e7245313/thumb/128.jpgClipping is a form of musical distortion that occurs when an electrical signal attempts to drive an amplifier beyond its maximum volume. Mathematically, we can model clipping as a nonlinear operation on signals that cuts off the amplitude of the signal at the value c, “flattening” it at any output value greater than c. If we express a clipped periodic signal as a Fourier series—namely, as a linear combination of sinusoidal functions which form a basis of the vector space C0(T, R) of all continuous, time-periodic, real-valued functions—we can interpret the individual terms in the Fourier series as overtones produced by the clipping operation which are added to the initial “fundamental” signal. In this thesis, we derive an explicit exact formula for the Fourier series of a clipped driven sinusoid as well as their asymptotics in the limit of maximum overdrive. Our analysis determines the volumes of each of the overtones, shedding a hing of light on the world of math behind music
Peaks & Valleys: Creating Network Models From Disordered Potentials in Quantum Hall Systems
No full texthttps://rdc.reed.edu/v1/resources/e052f921-bf3d-4abb-bb3d-90a99934d5f6/thumb/128.jpgIn the integer quantum Hall effect, electrons occupy delocalized states during transitions where the transverse resistivity is not quantized. Using network models that represent impurity potentials in the bulk of the system, we can predict the slope of the resistivity during these transitions as a function of the magnetic field, near its critical value. Research suggests that there’s a correspondence between the topological features of an impurity potential and the corresponding network model’s predictive power that needs to be identified. Here, we have shown that as we increase geometric disorder in an impurity potential, we see the number of polygons with faces in the corresponding network model approach a Poisson distribution on . We hope we can test classes of network models with this geometric property to determine how accurately they predict the critical exponent for the quantum Hall transition
Calculus on Twisty Stuff: The Local Index Theory of Dirac Operators
No full texthttps://rdc.reed.edu/v1/resources/acb98621-41df-4e70-81d0-9f744338e2b6/thumb/128.jpgIn this thesis we attempt to present a cohesive tour of the wonderful math associated to spin. Hailing originally from quantum physics, spin has brought forth a flurry of new ideas in topology, geometry, algebra, and mathematical physics. With the utility of Clifford multiplication, one can prove a dizzying array of results: obstructions to structures, integrality of topological invariants, Bott periodicity, and the positive mass conjecture for general relativity among others. We seek to prove a local index theorem, relating the analytical index of a Dirac operator to topological invariants of a Riemannian manifold. Along the way we establish some motivation for defining spin groups, construct them explicitly, build the framework of principal bundles and connections, and finally apply our theory in the analytic setting to prove a famous result about the A-genus of a manifold
Investigating the Regulation of Biological Pathways in the Cross-sex Behavioral Roles of Julidochromis transcriptus
No full texthttps://rdc.reed.edu/v1/resources/407d0c5a-7bd2-49c5-8dd0-1c0791aac11e/thumb/128.jpg"Cichlids are a well-known model for modern behavioral research due to their widespread radiation and complex social hierarchies. In my thesis, I will be exploring the biological pathways for regulation of social hierarchies during reproduction using the more well-studied Astatotilapia Burtoni as a reference animal and Julidochromis transcriptus as the model animal. In particular, female model animals are often understudied in research, making one of the key focal points of the thesis to investigate if females and males are using similar pathways to modulate phenotypic changes. Because J. transcriptus use a form of reproductive pairing across sexes where the big fish guards the outside of the nest and the small fish tends and protects the interior, they provide the perfect opportunity to compare changes in hormonal regulation when paired with a partner of a relatively bigger or smaller size. To do this, large outside nest guarding males and females were paired with an opposite sex smaller nest-tending partner and allowed to cohabitate and reproduce. Hormonal data was collected from the water and analyzed. This thesis focuses on the steroid hormones most associated with reproduction and social role: T, 11-KT, E2 and Pr. In addition, a secondary focus to my thesis revolves around tying together the pathways of steroid regulation with transcriptomic data from key parts of the brain involved in reproduction and social roles: the POA and vD. I also chose to include two centers of the brain known for sensory processing based on relevance in mate-choice and communication: the OT and TS. In order to collect samples for my planned transcriptomic analysis, I worked on creating and streamlining a procedure involving cryosectioning, identification, and brain punches. While I initially intended for my results to be entirely based on the analysis of transcriptomic data, I was unable to prepare and send out samples due to time constraints. The results and discussion of my thesis instead build on the gonadal steroid research through data analysis. I found that in both outside nest-guarding males and females there is a clear significant elevation in 11-KT, suggesting that outside nest-guarding male and outside nest-guarding female J. transcriptus use the same biological pathway to regulate their social roles.
Made to Move: Tracing the Construction of Hobo Identity Through Narrative
No full texthttps://rdc.reed.edu/v1/resources/290b3989-64b4-4377-982b-6851b5b245d4/thumb/128.jpgThis thesis is an exploration of how people who historically identify as hobos contributed to constructing the social category of “hobo” through their use of personal narrative. I attempt to display how the tradition of storytelling as a means for self-definition emerged after the Civil War and carried through to the post-World War II period. Hobos in the postwar period’s extrapolation of this tradition reflects their lineal continuity from the traditional hobos who came before them. What is different between prewar and postwar hobos is the function of this process of self-fashioning. Prewar, this reshaping was focused on romanticizing hobo lifestyle as a departure from social convention and restrictive power structures. In the postwar period, however, hobos sought to mold themselves into acceptable mobile subjects by reproducing systematic social hierarchies of exclusion and reinforcing defined conventional lifeways. My work draws on a series of personal narratives written by self-identified hobos across this vast time period. What emerges, is an illustration of the interplay between people within a social category and the social category itself. In navigating the embedded tensions between acceptable and threatening mobility, hobos were constantly reshaping themselves within changing socio-economic and political conditions
Lichen the Flames? Quantifying flammability for seven epiphytic species of the West Cascades
No full texthttps://rdc.reed.edu/v1/resources/de2d830c-1986-4130-8def-28ccb904a389/thumb/128.jpgEpiphytic lichens inhabit the canopy of forests within the West Cascades, contributing to the ecosystem as food sources, invertebrate habitat, and nutrient cyclers. While these forests historically do not experience frequent wildfires, fire suppression practices, alongside the effects of climate change, may lead to increased desiccation and a higher risk of crown fires. Previous literature claimed that lichens exceed other forest fuels in their flammability due to their high surface area to volume ratios and their ability to remain desiccated for long periods; however, no experimental evidence exists which supports these assumptions. Using the methods of Valette et al. (1990) and Ganteaume et al. (2013), I performed a series of flammability tests on hydrated and desiccated lichen and moss samples, to quantify the effect of species and morphology on flammability. I conducted 140 total flammability trials on abundant epiphytic species of the West Cascades: the lichens, Platismatia glauca, Hypogymnia inactiva, Lobaria pulmonaria, Lobaria oregana, Alectoria sarmentosa, and Usnea sp., as well as the moss, Antitrichia curtipendula. Using the flammability characterizations of Valette et al. (1990) and Essaghi et al. (2017), I found that all the lichens and mosses tested were extremely flammable while desiccated and only slightly flammable while hydrated. Significant differences existed across species and morphology for several flammability characteristics, with Hypogymnia inactiva and Platismatia glauca exhibiting the highest relative flammability rating while desiccated and Lobaria pulmonaria showing the highest relative flammability rating while hydrated. Foliose lichens displayed the highest average flammability characteristic measurements for both hydrated and desiccated treatments which disagrees with previous literature using surface area to volume ratios to predict relative flammability. This research demonstrates a need to recognize desiccated lichens as a source of highly flammable biofuel within the forest canopy and stresses the importance of identifying lichen refugia to protect fire-sensitive lichen species
Street Plazas and their effects on Local Businesses and Sociability
No full texthttps://rdc.reed.edu/v1/resources/6b115305-78ec-4afd-9da7-806773f8f126/thumb/128.jpgWith my thesis project I wanted to examine to what extent street plazas are beneficial to both business owners, the larger community and how to successfully activate these spaces. Street plazas are great places for the formation of long-lasting social ties, as well as a place to meet like-minded people. The street plaza program born from the Covid-era gained traction in 2022, initially stemming from Portland’s Livable Street strategy. This strategy encourages Portlanders to reclaim streets into public right of way and promotes placemaking activities. This topic is relevant to sociologists as it may shine light on the importance of high-quality public spaces as there are numerous benefits that come from having places to gather, areas to wind down, chat with strangers, etc. Past research has looked extensively at the tangible benefits of converting street space back into pedestrian friendly zones, but not so much how to effectively activate these spaces. Many of my findings pertain to ways of activating the space, as in, how to bring people back reliably and consistently. My goal was to uncover how these spaces are being activated, if they are, and why some plazas are doing better than others, focusing on Portland’s Street plazas specifically. To uncover this, I set out on a mission of conducting interviews with business owners/tenants, patrons, advocacy/association members, city council candidates and PBOT officials to get a clearer picture of how people are thinking about and utilizing these new areas. In a time of rising concern over crime that arose during and after the COVID pandemic, now more than ever it is important to be an advocate for what you believe is right. It is up to sociologists to showcase the utility of public space, and there’s no better place to start than with our streets if we are to transform Portland into the vibrant city we deserve
"Uses of the Erotic" in the Poems of Audre Lorde, Rita Dove, and Ntozake Shange
No full texthttps://rdc.reed.edu/v1/resources/1efe2676-3933-4f24-ac47-e28e67818609/thumb/128.jpgThe purpose of this thesis is to explore the significance and relevance of Audre Lorde’s body of work as it concerns the connections between spirit, mind, and body in her 1978 speech, “Uses of the Erotic: The Erotic as Power.” Lorde’s notion of the erotic invites all people, and particularly individuals of intersecting racial, sexual, and gendered identities, to use their senses and emotions to reclaim their existences as equal and united beings in a world that necessitates holistic spirituality and love. My project is to read the poetical works of Audre Lorde, Rita Dove, and Ntozake Shange through the lens of Lorde’s theory of the erotic
A Decade of Integration on the Southern Border
No full texthttps://rdc.reed.edu/v1/resources/e1233295-5c29-4b4c-a4b7-835bd3a72aca/thumb/128.jpgThis study examines the economic and social outcomes as a measure of integration for Hispanic or Latino individuals living in border states. To conduct this investigation, I used data from the American Community Survey 2012-2022. I measure an indicator of both economic and social assimilation across ten years. The results show a lack of significant change in Hispanic or Latino assimilation between 2012 and 2022, instead demonstrating the strength of the status quo within Hispanic or Latino counties
Hypervalent Iodine and Iodonitrene in the Synthesis of Pyrazoles and Hydrazones
No full texthttps://rdc.reed.edu/v1/resources/265ed8f0-0524-407c-90a6-cc8d11bbb07f/thumb/128.jpgPyrazoles are a prevalent nitrogen functional group in many anti-coagulant and anti-inflammatory medications. Though these medications have been around for some time, syntheses of pyrazole-based pharmaceuticals still have room for some improvement. Pyrazoles are formed from the cyclization of hydrazone-containing molecules, which are most often made using hydrazine. Since hydrazine is toxic and used as rocket fuel propellant, industrialization of hydrazone syntheses has had some difficulties. From the recent advancements of hypervalent iodine chemistry, iodine-based reagents have been shown to form nitrogen-nitrogen bonds. Using hypervalent iodine reagents, it is possible for hydrazones to be formed. Iodonitrenes can insert adjacent to some nitrogen species, which can be further modified to form a hydrazone. This work attempts to form these hydrazones to improve the knowledge around hypervalent iodine reactions and to provide an alternative synthesis pathway for medications that contain pyrazoles