Searching for the Lowest Metallicity Galaxies in Our Local Universe

Hsyu, Tiffany ProQuest Dissertations & Theses University of Cali 2020 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Observational determinations of the primordial light element abundances produced during Big Bang Nucleosynthesis (BBN) provide an important test on our current understanding of the Universe and the Standard Model due to their sensitivities to two parameters at the time of BBN: the baryon density and the expansion rate of the Universe. The primordial helium-4 abundance is particularly sensitive to the latter, which is partly driven by the number of effective neutrino species. In this thesis, I present a new observational survey to discover near-pristine environments in our local Universe whose properties can be used to determine the latest value of the primordial 4He abundance.I first describe the details of our observational survey, which uses photometry from the Sloan Digital Sky Survey (SDSS) to identify candidate metal-poor galaxies. We use the Kast spectrograph on the Shane 3m telescope at Lick Observatory to obtain confirmation spectroscopy and follow up on a subset of these systems using LRIS and NIRSPEC/NIRES at Keck Observatory, which we name the Primordial Helium Legacy Experiment with Keck (PHLEK) survey. The high S/N optical and near-infrared (NIR) spectroscopy of the PHLEK sample enable a direct measurement of the electron temperature for the oxygen abundance and the detection of a suite of HeI lines for the helium abundance.Our survey results include the discovery of the Little Cub, one of the lowest-metallicity star-forming galaxies currently known. The Little Cub has a gas phase oxygen abundance about a twentieth solar metallicity and is a testament to the success in picking out metal-poor systems from photometry alone.Finally, I describe our code yMCMC, which uses the Markov Chain Monte Carlo (MCMC) technique to explore an 8-dimensional parameter space and solve for the parameters that best describe our observations. We supplement our PHLEK sample with SDSS spectroscopy and existing low-metallicity systems in the literature. Using systems well-modelled by yMCMC, we make an extrapolation to the primordial helium number abundance ratio, finding yP=0.0805+/-0.0017. When combined with the existing primordial deuterium abundance, this places constraints on the baryon-to-photon ratio and effective number of neutrino species in agreement with the Standard Model.

Lorentz boosted frame simulation technique in Particle-in-cell methods

Yu, Peicheng ProQuest Dissertations & Theses University of Cali 2016 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

In this dissertation, we systematically explore the use of a simulation method for modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) method, called the Lorentz boosted frame technique. In the lab frame the plasma length is typically four orders of magnitude larger than the laser pulse length. Using this technique, simulations are performed in a Lorentz boosted frame in which the plasma length, which is Lorentz contracted, and the laser length, which is Lorentz expanded, are now comparable. This technique has the potential to reduce the computational needs of a LWFA simulation by more than four orders of magnitude, and is useful if there is no or negligible reflection of the laser in the lab frame. To realize the potential of Lorentz boosted frame simulations for LWFA, the first obstacle to overcome is a robust and violent numerical instability, called the Numerical Cerenkov Instability (NCI), that leads to unphysical energy exchange between relativistically drifting particles and their radiation. This leads to unphysical noise that dwarfs the real physical processes. In this dissertation, we first present a theoretical analysis of this instability, and show that the NCI comes from the unphysical coupling of the electromagnetic (EM) modes and Langmuir modes (both main and aliasing) of the relativistically drifting plasma. We then discuss the methods to eliminate them. However, the use of FFTs can lead to parallel scalability issues when there are many more cells along the drifting direction than in the transverse direction(s). We then describe an algorithm that has the potential to address this issue by using a higher order finite difference operator for the derivative in the plasma drifting direction, while using the standard second order operators in the transverse direction(s). The NCI for this algorithm is analyzed, and it is shown that the NCI can be eliminated using the same strategies that were used for the hybrid FFT/Finite Difference solver. This scheme also requires a current correction and filtering which require FFTs. However, we show that in this case the FFTs can be done locally on each parallel partition. We also describe how the use of the hybrid FFT/Finite Difference or the hybrid higher order finite difference/second order finite difference methods permit combining the Lorentz boosted frame simulation technique with another "speed up" technique, called the quasi-3D algorithm, to gain unprecedented speed up for the LWFA simulations. In the quasi-3D algorithm the fields and currents are defined on an r--z PIC grid and expanded in azimuthal harmonics. The expansion is truncated with only a few modes so it has similar computational needs of a 2D r--z PIC code. We show that NCI has similar properties in r--z as in z-x slab geometry and show that the same strategies for eliminating the NCI in Cartesian geometry can be effective for the quasi-3D algorithm leading to the possibility of unprecedented speed up. We also describe a new code called UPIC-EMMA that is based on fully spectral (FFT) solver. The new code includes implementation of a moving antenna that can launch lasers in the boosted frame. We also describe how the new hybrid algorithms were implemented into OSIRIS. Examples of LWFA using the boosted frame using both UPIC-EMMA and OSIRIS are given, including the comparisons against the lab frame results. We also describe how to efficiently obtain the boosted frame simulations data that are needed to generate the transformed lab frame data, as well as how to use a moving window in the boosted frame. The NCI is also a major issue for modeling relativistic shocks with PIC algorithm. In relativistic shock simulations two counter-propagating plasmas drifting at relativistic speeds are colliding against each other. We show that the strategies for eliminating the NCI developed in this dissertation are enabling such simulations being run for much longer simulation times, which should open a path for major advances in relativistic shock research. (Abstract shortened by ProQuest.).

From Blurry Space to a Sharper Sky: Keeping Twenty-three Years of Astronomical Data Alive

Boscoe, Bernadette Marie ProQuest Dissertations & Theses University of Cali 2019 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

In compute-heavy and data-driven scientific fields, digital data play a central role in the creation of knowledge. For science fields that rely on data that can only be observed once, the preservation of these data is crucial to analytic processes. Time-domain astronomy is one such field, involving celestial observations such as exploding supernovae and passing comets. This dissertation examines the data and code practices of a university-based astronomy research group who have managed to keep their data "alive" for twenty-three years with limited resources. Keeping data alive means both understanding the knowledge contained within and having the associated technologies operable. The human aspects necessary to keep data alive are equally as important as the technological elements. This three-year ethnographic research project examines the factors involved in analyzing, preserving, and curating astronomy data as these data wend their way through socio-technical, physical, and digital infrastructures that shape and are shaped by the knowledge contained within the data. Dissertation research took place at six field sites: the case study's university, the observatory of the case study, the archive of the observatory, and three other astronomy archives. The findings of this study show two main ways that data are kept alive in astronomy: 1) Publicly: Data are curated and preserved with the intention to be made available via web interfaces, engendering relationships among stakeholders, and 2) Privately: Data are preserved by astronomy research groups at universities that continually reuse them and their associated code, in a collaborative way. Findings suggest how a better understanding of the relationships between public and private astronomy data can inform scientific data preservation and curation practices.

Activist Leadership Development: An Engine for Social Justice Transformation

Elzein, Kareem Allen ProQuest Dissertations & Theses University of Cali 2021 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Student activists have been an historic driver of higher education social justice reform. While this form of leadership is central to improving equity outcomes in higher education, scholars and practitioners often view organizational change as a top-down process centering senior administrators, staff, and faculty. Empowering student activists as more than token stakeholders in organizational transformation processes supports social justice outcomes, as well as broader institutional goals, vis-a-vis promoting civic engagement, leadership development, and knowledge production. Efforts to strengthen this type of student leadership require institutional resources that are supportive of activist leadership development, and administrative efforts to facilitate student activist’s engagement in institutional change processes. This dissertation study is an institutional ethnography of the Bruin Excellence & Student Transformation Grant Program (BEST), a student activist leadership development program at the University of California, Los Angeles that sought to develop and empower student activist leaders. Specifically, the institutional ethnography utilizes autoethnography, centering my experiences as co-founder and leader of BEST, to explore the history, conceptualization, evolution, and impact of BEST in fostering student leadership and campus transformation. Using personal narrative to tell the story of the program, this research triangulates autoethnographic research with qualitative and quantitative data collected by the program from 2016-2020. This narrative explores how leadership development programs can center student activist leadership growth and uncover the complex ways students engage in leadership to support equitable campus changes. Findings from the study contextualize the challenges and opportunities of activist leadership development programs within the often-antagonistic environment of a top tier public university. Institutional infighting over diversity resources and structural barriers such as funding and inconsistent administrative support pose an obstacle to impactful social justice initiatives. Further, leadership development programs working with activist students must seek to develop trusting relationships based on mutuality, socioemotional support, and an authentic commitment to social justice principles and practices. Findings from this research will necessitate the expansion of equitable policies and resources that support and affirm student activist leaders within higher education institutions.

Improving Cosmological Distance Measurements with Type Ia Supernovae: From Pixels to Dark Energy

Boone, Kyle ProQuest Dissertations & Theses University of Cali 2019 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

In the late 1990s, precise distance measurements with Type Ia supernovae (SNe Ia) were used to show that the expansion of the universe is accelerating. One possibility is that this accelerated expansion is due to an additional form of energy referred to as "dark energy" which contributes roughly 70% of the total energy in the present day universe. The properties of dark energy are not currently well-constrained, and a wide range of different cosmological probes are currently being designed to explore the fundamental nature of the accelerated expansion of the universe. SNe Ia have remained one of the strongest cosmological probes, and upcoming experiments such as the Large Synoptic Survey Telescope (LSST) are expected to discover over 100,000 SNe Ia that can be used for cosmology. The uncertainties on cosmological parameters derived from these large samples of SNe Ia will be entirely dominated by the systematic uncertainties of distance measurements to SNe Ia. In this dissertation, we discuss several different methods of improving the systematic uncertainties in distance measurements to SNe Ia.This dissertation is split into three main chapters each discussing how to improve a different aspect of distance measurements to SNe Ia. In Chapter 2, we examine how instrumental calibration can affect these distance measurements, and discuss a new anomalous behaviour of CCD readout electronics related to the binary encoding of pixel values that affects most astronomical instruments currently in use. For the Nearby Supernova Factory, this anomaly introduces a dispersion in the measured B-band/U-band magnitudes of 0.11 mag/0.51 mag for the faintest 20% of measurements.Another major source of systematic uncertainty in distance measurements to SNe Ia is intrinsic variation of the SNe Ia. In Chapter 3, we develop a new method of parametrizing SNe Ia using manifold learning to generate a non-linear decomposition of the intrinsic diversity of their spectra near maximum light. We identify regions of the parameter space of SNe Ia where previous standardization methods such as SALT2 have biases of up to 0.3 mag, and show how correlations between host galaxy properties and distance estimates are greatly reduced when standardizing SNe Ia using our new parametrization.Finally, in Chapter 4, we discuss how upcoming surveys such as LSST will need to rely on photometric classification to identify the majority of the transients that they discover, which means that samples of SNe Ia used for cosmology will be contaminated with other types of transients. We developed a set of techniques for photometric classification to address the fact that spectroscopic subsamples used for training classifiers are typically highly biased compared to the full samples of transients and variables that will be discovered. Using these techniques, we built a photometric classifier that won the PLAsTiCC photometric classification challenge out of 1,094 competing teams.

Prototyping the Developer Experience for Data Science Practitioners and Instructors

Kross, Sean Michael ProQuest Dissertations & Theses University of Cali 2022 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Data science encompasses the most prominent collection of methods for creating scientific knowledge in the 21st century. Currently, data scientists must navigate a wide-ranging and often incoherent ecosystem of tools, in addition to organizing sociotechnical interactions with colleagues across many fields of expertise.This predicament motivates my thesis: The elements of data science work that are based in human expertise and social relationships must be integrated into existing programming workflows to create the developer experience that data scientists require to be successful.This dissertation supports my thesis by presenting three empirical studies and two tools. First, I investigated how professional data scientists teach novices about data science focused programming workflows, including how to adapt software development tools to their work, how to navigate the full depth of the stack of technologies that data science relies on, and how to use their tools to help communicate their findings. Then I explored how a team of academic data scientists repurposed the tools from their everyday data science work to create a data science course designed to reach traditionally underrepresented groups in computing. Finally, I examined how consulting data scientists interact with their clients, how their working relationships take them beyond well-characterized programming-oriented cycles, and how they achieve success by integrating designerly work into their data analysis process.These studies inspired me to develop two tools: 1. Datamations animates each step in a data analysis pipeline via transitions that show how rows, columns, and cells move within a data frame. 2. Tidy Data Tutor creates step-by-step interactive illustrations for a data analysis pipeline, so that every individual cell can be tracked.The main research findings of this dissertation are that data scientists adapt software engineering tools to fit into their own workflows, and that data scientists must communicate the uncertainty that they face in their work to novices. Additionally, this dissertation found that several nested cycles are required for data scientists to achieve success in collaboration with their colleagues. Finally, my prototype tools showed that animations and illustrations derived from data wrangling code can help convey a clearer understanding of data analysis pipelines.

Experimental Investigations of Convective Turbulence in Planetary Cores

Hawkins, Emily Kate ProQuest Dissertations & Theses University of Cali 2020 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The magnetic fields of planets and other bodies are created and sustained due to the turbulent motions of an internal fluid layer, a process known as dynamo action. Forward models are required to characterize the dynamics of rotating convective turbulence driving dynamo action due to the inability to obtain direct measurements of the internal fluid layers of planetary bodies. The characteristic flow velocities and length scales of dynamo systems remain poorly constrained due to the difficulty of modeling realistic planetary core conditions. Thus, the goal of this dissertation is to explore these key properties of core-style convection. To do so, I have conducted novel experiments aimed to better quantify the features of quasi- geostrophic turbulence using the UCLA large-scale rotating convection device, ‘NoMag’.I have completed a systematic study to simultaneously measure the heat transfer and bulk velocities of different rotating convective regimes at some of the most extreme laboratory conditions possible to date. The study of heat transfer is employed in most forward models of core-style convection. In laboratory experiments in particular, due to the relative difficulty of collecting velocity measurements, those of heat transfer alone are assessed, the dynamics of which are assumed to describe the the bulk velocity dynamics of the system. On the contrary, I utilize laser doppler velocimetry to obtain measurements of bulk velocities concurrently with the collection of temperature measurements for the characterization of system heat transfer. I find that heat transfer behavior is consistent with the results of past studies and is largely controlled by boundary layer dynamics. I further find that velocity behaviors do not directly coincide with heat transfer behaviors in the parameter space studied. Instead, I show that a dynamical flow regime of quasi-geostrophic turbulence relevant to core flows is robustly reached, suggesting that it is possible to access realistic bulk dynamics in models that remain far from planetary core conditions.Using the results of this study, I estimate the characteristic length scales of the flows of each experiment. These estimates from my data are compared with length scale estimates of numerous numerical models of planetary core convection. I conclude from this meta-analysis of forwards models that all evidence to date suggests that the theorized characteristic length scales of planetary dynamo systems co-scale with one another and are thus non-separable.In two other studies that comprise the remainder of this dissertation, I further examine the applicability of laboratory models towards planetary settings. An experimental study on the influence of centrifugal buoyancy on rotating convection in water and in liquid metal was completed, where results agree with the recent numerical work of Horn and Aurnou (2018). It is found that the transition from Coriolis to centrifugally dominated convection depends on the strength of the centrifugal buoyancy relative to the gravitational buoyancy and the geometry of the cylinder in which experiments are conducted. These results are useful to ensure that the regime of rotating convection explored in a given experiment is relevant to planetary core flows, i.e. not centrifugally dominated. Separately, I conducted a series of spin up experiments with well-established theory to calibrate the NoMag apparatus and its measuring components. Further, the results from spin up experiments conducted with rough boundaries might have geophysical implications for the possible viscous coupling at Earth’s core mantle boundary, as well as turbulent mixing in the global ocean.The results of the studies presented in this dissertation clarify the relevance of long theorized and poorly tested dynamic length and velocity scalings of planetary core flows. Flows that are quasi-geostrophically turbulent are robustly observed in the laboratory data collected in this dissertation. The need for next generation models of planetary core flows is motivated by the results of the work herein. In particular, studies in which the characteristic length scales of core-style flows are directly quantified will undoubtedly enhance ourunderstanding of the multi-scale turbulent physics driving planetary dynamo systems.

Addressing Transfer Shock: How Community College Transfer Students Develop Peer-to-Peer Social Connections at a Four-Year University

Shayestehpour, Anousheh ProQuest Dissertations & Theses University of Cali 2020 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Through in-depth interviews and written reflections, this study investigated how community college transfer students at a large, public, four-year, research university developed social connections with their in-class peers, their perceptions of how these social connections influenced their resilience, and the role of the institution in peer-to-peer social connection making. Research suggested that transfer students who experience a sharp drop in GPA during their first-term at the university, a phenomenon known as transfer shock, were more likely to drop out if the dip was not corrected within the next academic term (Hills, 1965). Transfer students who developed social connections and a sense of belonging to their new institution during their first term were more likely to perform better in their coursework and avoid transfer shock. Current literature on the social integration of community college transfer students focused on formal interventions such as orientations and mentorship programs, or student participation in university extra-curricular activities including events or clubs. This study uncovered how social connections between community college transfer students formed outside of participation in extra-curricular activities in order to address the limitations of this typically commuter population.This dissertation presented findings based on the personal stories of six male and six female community college transfer students who were commuters between the ages of 19–26, representing both STEM and non-STEM majors. This study found that peer-to-peer social connections formed outside of extra-curricular activities were established primarily in or around the classroom. The participant narratives confirmed social connections to native and transfer student classmates played a positive role in their transition within and to the four-year university. Such social connections provided access to shared academic resources and unique navigational capital which supported participant resilience (academic and emotional persistence over time leading to on-time graduation). The institution was perceived as having facilitated the development of peer-to-peer social connections when academic programs were designed so that students were likely to share multiple classes in the same term and/or when collaborative work was integrated into course curriculum. This dissertation concluded with recommendations for four-year institutions on the ways in which the classroom can serve as an effective and supportive environment for peer-to-peer social connection making.

Taming Giants: Studies on the Growth, Regulation, and Evolution of Dusty, Star-Forming Galaxies in the Early Universe

Long, Arianna S ProQuest Dissertations & Theses University of Cali 2022 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Half of all cosmic starlight is obscured by dust and re-radiated at cooler, infrared wavelengths. The majority of stellar mass is built in these dust-obscured regions at z > 0.5—with the most extreme manifestation taking place in a rare population of galaxies: dusty, star-forming galaxies (DSFGs). DSFGs form stars at extreme rates (~102-3 M☉/yr), becoming extremely massive (M* ≥ 1010 M☉) in just a few hundred million years. Prodigious star formation generates abundances of dust that obscures starlight, making some DSFGs nearly invisible to even the deepest rest-frame ultraviolet and optical surveys. Though rare in the local Universe, DSFGs are a thousand times more populous at z ~ 1–3. What is their evolutionary fate and what might their descendants look like today? In my doctoral research, I led detailed case studies, large statistical analyses, and I developed an empirically-based numerical model to uncover critical insights into the answers of these questions. I focus on constraining the stellar growth and evolution of DSFGs discovered with the Herschel Space Observatory, complemented by data from the Chandra X-ray Observatory, Hubble Space Telescope (HST), Spitzer Space Telescope, and other ground-based telescopes.First, I present a detailed case study on a protocluster of DSFGs found at z = 4, the Distant Red Core (DRC). In this work, I presented the first measurement of both the stellar and cold gas content in a massive, z > 3 protocluster, and determined that this protocluster occupies an exceptionally massive dark matter halo (≳ 1014 M☉), potentially in tension with a simple Lambda CDM cosmological model. I forward evolved the protocluster members to show that these galaxies will likely become the massive quiescent ellipticals dominating cluster cores by z ≈ 2–3. Then, I present my first lead-author work where I showed that there was no statistically significant evidence of star formation suppression in dusty galaxies with actively growing black holes when compared to those without. This implies that feedback and heating from actively growing supermassive black holes may not be the primary mechanism that shuts down of star formation in massive galaxies at z > 1. I also derived the first statistically significant quantification of black hole versus star-forming emission as a function of wavelength, which can be used to argue for/against certain photometric filters as "pure'' star-formation indicators in distant, dusty galaxies. Finally, I present my latest in-progress work where I use empirical data on dusty star-forming galaxies to create a novel, numerical model that re-shapes the primary function describing stellar mass assembly in the Universe: the stellar mass function. Using the infrared luminosity function as a nearly-complete census of dust-obscured galaxies, I built a Markov Chain Monte Carlo model that infers the stellar masses of mock populations of dusty galaxies throughout cosmic time. Current results show that the massive end (M* ≥ 1011 M☉) of the most robust galaxy stellar mass functions in the literature are deficient by up to an order of magnitude; this is of major concern for galaxy evolution models, which often invoke extreme feedback prescriptions (e.g. AGN) to prevent galaxies from growing much beyond this pivotal mass. Using simple assumptions to forward evolve these mock DSFGs, I demonstrate that massive DSFGs at early times can evolve to match the observed population densities of massive quiescent galaxies at later times, and are therefore the likely dominant ancestral population. Many of the results and predictions presented in this thesis are immediately testable with with uniformly-selected galaxy samples from Cycle 1 JWST GTO / ERS programs.

Universals and Variation in Language and Thought: Concepts, Communication, and Semantic Structure

Carstensen, Alexandra B ProQuest Dissertations & Theses University of Cali 2016 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Why do languages parcel human experience into categories in the ways they do, and to what extent do these categories in language shape our view of the world? Both language and nonlinguistic cognition vary across cultures, but not arbitrarily, suggesting that there may be universal constraints on how we talk and think. This dissertation explores the sources and consequences of universals and variation in language and thought in four parts. The first study examines a major premise of the universalist view of cognition, that speakers of all languages share a universal conceptual space, which is partitioned by the categories in language. Previous research on color cognition supports this view; when English speakers successively pile-sort colors, their sorting recapitulates an independently proposed hierarchy of color semantics across languages (Boster, 1986). Here I extend that finding to the domain of spatial relations. Levinson et al. (2003) have proposed a hierarchy of spatial category differentiation, and I show that English speakers successively pile-sort spatial scenes in a manner that recapitulates that semantic hierarchy. This finding provides evidence for a specific hierarchy of spatial notions as a model of universals in conceptual structure, and suggests that universal patterns observed across languages reflect general cognitive forces that are available in the minds of speakers of a single language. The second project of this dissertation demonstrates a process by which domain-specific conceptual universals and more general communicative pressures may shape categories in language, extending a previous account (Regier et al., 2015) of semantic universals and variation. In particular, I show that human simulation of cultural transmission in the lab produces systems of semantic categories that converge toward greater informativeness, in the domains of color and spatial relations. These findings suggest that larger-scale cultural transmission over historical time could have produced the diverse yet informative category systems found in the world's languages. This work supports the communicative efficiency account of semantic universals and variation and establishes a process through which categories in language become increasingly efficient and increasingly universal. The third study extends the previous account of categories in language to cognition more broadly, showing that the same principles that govern efficient semantic systems also characterize nonlinguistic cognition. I provide an account of spatial cognition in which conceptual categories optimize the trade-off between informativeness (making for fine-grained and intuitively organized spatial categories) and simplicity (limiting the number of categories). I find that pile sorts made by speakers of diverse languages match this universal account more closely than they match the semantics of the sorter's native language. These results suggest that across languages, spatial cognition reflects universal pressures for efficient categorization, and observed universals in category structure and granularity result from these pressures. The final project of this dissertation probes the role of language in online spatial reasoning, using linguistic interference to prevent participants from relying on language in solving a spatial task. In previous work, adult English speakers have been shown to use a spatial frame of reference that differs from that of nonhuman primates and toddlers (Haun et al., 2006), suggesting that learning the spatial frame of reference used in English may motivate a switch away from universal modes of spatial thought. I find that under linguistic interference, despite a sharp increase in error, adult English speakers fail to readopt the spatial frame of reference used by nonhuman primates and toddlers. This finding rules out the possibility that language affects spatial frames of reference online and accordingly argues against Kay and Kempton's (1984) account, which predicts a removable online role of language. This result raises the stakes of the debate over the role of language in nonlinguistic spatial frames of reference---either something other than language causes alignment between linguistic and nonlinguistic frames of reference, or language learning fundamentally restructures nonlinguistic spatial cognition in a way that is difficult to reverse. The findings of this dissertation in the domain of space, taken together with parallels in other cognitive domains, reinforce an emerging consensus on the relation of language and thought, by which all people share a universal conceptual foundation that may be altered by language. The research here further elaborates this account, suggesting that universals and variation in both language and thought may derive to some extent from general principles of efficiency. At the same time, it challenges the generality of a classic formulation of this view (Kay & Kempton, 1984), motivating future research. In both complementing and challenging an emerging consensus on language and thought, this dissertation informs our view of language, a defining feature of human cognition, and contributes to a more complete understanding of the nature of thought.