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Non-volatile programmable photonics based on phase-change materials
No full textThesis (Ph.D.)--University of Washington, 2023Programmable photonics can enable a plethora of exciting applications from next-generation optical interconnects to quantum information technologies. Conventionally, photonic systems are tuned by mechanisms such as thermos-optic effect, free carrier dispersion, electro-optic effect, or mechanical movement. Although these physical effects allow either fast (> 100GHz) or large contrast (> 60dB) switching, they are not optimal for programmability which does not require frequent switching. Phase-change materials (PCMs) can offer an ideal solution thanks to their reversible switching, large index contrast, and non-volatile behavior, enabling a truly ‘set-and-forget’ switch element with no static power consumption. Recent years, we have indeed witnessed the fast adoption of PCMs in programmable photonic systems, from photonic integrated circuits (PICs) to meta-optics. Despite the tremendous progress in the field, a few remaining challenges must be addressed before the technology can be scalable and ultimately commercialized. For example, the high optical loss of the traditional PCMs, such as Ge2Sb2Te5 (GST), is prohibitive for large-scale PICs. Secondly, the energy required to electrically switch PCMs remains to be high (~tens of nano-joules), and the device footprint is still large (> 64µm). Lastly, so far there has not been an ideal solution towards non-volatile phase-only control in the free-space due to the high loss of the PCMs and microheaters. In this dissertation, we aim to circumvent these limitations. First, we demonstrated non-volatile phase modulation (\Delta\phi~0.17\pi) with near zero insertion loss in both Si and SiN integrated photonics using a low-loss PCMs Sb2S3. Through device engineering, an ultra-compact (33µm coupling length) directional coupler switch was realized based on Sb2Se3. Individual control of the phase and coupling in racetrack resonator was achieved. We further showed that ultra-low switching energy down to 8.7±1.4aJ/nm3 can be achieved using graphene microheaters for tuning the PCMs with excellent endurance over 1,000 cycles. Finally, leveraging a high-Q metasurface, we demonstrated non-volatile phase-only modulation of free-space light with ~0.2π phase shift and near zero change in intensity. Our work represents a crucial step in the development of disruptive non-volatile photonic technologies based on PCMs
Analisis daya dukung komoditas serealia terhadap ketahanan pangan Kabupaten Buleleng
No full textThe increase in population has an impact on the reduction in the area of productive agricultural land due to land conversion for various needs. This causes a decrease in food production so that food availability is lower and unbalanced with the demand or needs of the population. It is essential to know the carrying capacity of land as an illustration of a region's ability to meet its population's basic needs. This study aims to analyze the occurrence of conversion of agricultural land and its impact on the carrying capacity of land on food security in Buleleng Regency. The research is qualitative and descriptive, utilizing secondary data on agricultural land area, harvested area, production value, and population in ten years (2012-2021). The results showed that the carrying capacity of food fields in Buleleng Regency was low because they could not be self-sufficient or were in a deficit condition. This is due to the rapid population increase and agricultural land conversion, especially paddy fields. The authors thank the reviewers and the IASSF team for supporting this research
Statistical Methods for Official Statistics and Mortality Estimation
No full textThesis (Ph.D.)--University of Washington, 2023This dissertation develops statistical methodology for small area estimation, the analysis of official statistics, and mortality estimation. All methods are developed with the statistical challenges faced in data from low- and middle-income countries in mind. We first consider a problem in small area estimation known as benchmarking, where subnational estimates must agree in some sense with a national estimate or estimates. We then consider two related problems addressing data challenges specific to low- and middle-income country child mortality data, where data comes from a survey, is interval censored, and may need to be smoothed across time to ensure reasonable and precise estimates in situations with little data. The outline of the dissertation is as follows. In Chapter 2, we propose a benchmarking method for subnational estimates of a proportion in a setting where a national estimate is available with uncertainty. In Chapter 3 we develop a pseudo-likelihood approach to mortality estimation that allows us to obtain continuous mortality curves for children under the age of 5 across time from interval-censored survey data. In Chapter 4 we consider different temporal smoothing models for the direct estimates produced in Chapter 3, and develop a multivariate random walk prior to simultaneously smooth multiple, correlated summaries across time. Finally, we conclude with discussion of future work in Chapter 5
Pavement Winter Operations in Cold Regions
No full textDeicing and anti-icing chemicals are both used to improve the mobility of motorists in cold climates. Deicers are applied to melt and break bonded snow and ice. Anti-icers are proactively applied before ice formation to prevent and weaken the bond between the pavement surface and ice. This study evaluated a laboratory testing protocol to examine the performance of different deicing and anti-icing materials under different conditions for efficient winter maintenance operations. For this purpose, this study used three deicers—liquid calcium chloride (CaCl2), liquid potassium (K), and granular sodium acetate (NaCl) (i.e., D1, D2, and D3)—and two anti-icers—magnesium chloride (MgCl2) with two different inhibitors (i.e., A1 and A2). The proposed laboratory evaluation protocol included three tests: a friction test, an accelerated loading test, and a debonding test. The results demonstrated that the following: 1) All test products were effective at melting the ice and weakening the bond between the pavement surface and ice. 2) Better performance of various products was obtained at a higher application rates. 3) Various chemicals had comparable friction performance. 4) The accelerated loading test with a three-wheel polishing device indicated that all test products were effective on both asphalt and concrete surfaces; however, deicers D2 and D3 had better performances than the other products. 5) A new debonding test was used to evaluate the effectiveness of deicers/anti-icers at weakening the bond between the ice and test surfaces, and the test chemicals were found to reduce the shear force required to break the bond between the ice and test surfaces. On the basis of the results of this study, the proposed three testing protocols combined can provide a comprehensive assessment of the performance of various products under different environmental and operational conditions for efficient winter maintenance operations.US Department of Transportation
Pacific Northwest Transportation Consortium
University of Idah
Creation & Performance of Solo Show Their Eyes Get Big
No full textThesis (Master's)--University of Washington, 2023Their Eyes Get Big is a solo performance about the reverbrations of sexual assault and bystander responses in my life. In this performance, I attempt to bring the audience into my own experience of sexual assault, using stories from my life that have been abidingly influential, in order to offer a lens for current and systemic sexual violence that I and my academic community have been witness to. By all audience reports, I was successful: Audience members responded that they found the piece moving, and that they were still thinking and talking about Their Eyes Get Big much later. The success and impact of the performance can be directly attributed to synthesizing and application of learnings from the Professional Actor Training Program: Identifying and honoring my impulses; my expanded capacity for self-reflection, self-assessment, and constructively seeking and incorporating feedback; and using rehearsal and performance to learn, respond to audience, deepen work and make discoveries
Leveraging the awesome power of Saccharomyces to probe the evolution of genetic networks.
No full textThesis (Ph.D.)--University of Washington, 2023Causal loci for phenotypes of interest do not exist in isolation, but rather in complex, densely connected groups termed genetic interaction networks. Given the degree of functional conservation shared with humans, S. cerevisiae represents an excellent model organism for understanding the connection of genetic networks to complex traits. Within the field, questions remain about the conservation of genetic networks among various, distantly related species. To address this, I studied how functional rewiring has evolved in S. cerevisiae and its most distantly related Saccharomyces relative, S. uvarum. I used differential gene essentiality as my phenotype of interest, which was previously observed to occur for 12% of comparable orthologs. Differentially essential orthologs between S. cerevisiae and S. uvarum are capable of functional complementation, pointing towards changes in interaction partners as the genetic basis. My work focused on identifying these evolutionary changes in the genetic network between species by mapping these new interaction partners. Focusing on the differentially essential orthologs that are essential in S. cerevisiae only, for select candidate genes I leveraged the power of transposon mutagenesis and whole genome sequencing to perform genome wide reciprocal hemizygote screen in these hybrids to map loci with differential phenotypic results depending on the identity of the mutated parental allele. Analysis of transposon insertion rates across both parental genomes in the population will make it possible to identify novel genetic interaction partners that have been gained or lost for the non-essential S. uvarum ortholog. Mapping the genetic network changes among these two 20 mya diverged Saccharomyces yeasts will provide new insight into the level of conservation across the Eukaryotic tree of life
Breaking the Automobile Addiction: A Vision for Transit-Oriented Development in Seattle
No full textThesis (Master's)--University of Washington, 2023Cities have recognized the need to shift to a more walkable, transit-friendly urban form to reduce reliance on the personal automobile. Since the concept of transit-oriented development (TOD) was coined by Peter Calthorpe in the late 1980s, it has become a buzzword–along with walkability and pedestrian scale–used in virtually all visioning plans, comprehensive plans, and master plans, yet the implementation of these concepts in the United States is poor at best. Conflicting priorities, differing demands, or a disregard for context-specific solutions often result in projects that do not achieve the stated goals. Developments continue to cater to the automobile and little incentive exists to encourage different behavior. This research aims to identify and explore the best examples of how other U.S. cities have successfully integrated TOD into existing communities, and compare these to completed and planned developments in the Seattle metropolitan area. This thesis compares TOD projects in three other states (California, Colorado, and Oregon) with three projects in Seattle, Washington. The comparison focuses on the degree to which certain physical characteristics typically associated with walkable and transit-oriented developments–density, proximity and diversity of businesses or services, and demand management of automobiles (namely parking)–are present in Seattle and how those characteristics are prioritized to meet specific needs of the project area. By understanding how to balance the TOD elements with the needs of the neighborhood through a case study exercise, recommendations can be provided to guide future TOD in Seattle and other U.S. cities to achieve a reduction in automobile reliance, and an increase in walking, cycling, and public transportation use.
There is no single recipe for a successful TOD development. The most successful TODs are those that balanced the TOD elements to respond to the needs and existing elements of the neighborhood depending on its characteristics and context. For example, TOD in urban areas should prioritize vehicle demand management strategies while taking advantage of the existing density and destinations. Suburban retail center environments should prioritize building up a stock of dense residential housing but may rely on the adjacent destinations and services that already exist in the area. Working within the existing urban context and applying TOD elements in ways that correspond with the character of the neighborhood offers the best foundation to drive change in the urban environment
Moiré control of multilayered graphene systems
No full textThesis (Master's)--University of Washington, 2023Introducing a small rotation, or twist, between graphene multilayers gives rise to moiré patterns. At a certain magic angle, flat electronic bands are formed and the resulting structure gives rise to highly tunable correlated and topological states. To date, twisted graphene heterostructures comprising monolayer and/or bilayer graphene constituents have been shown to host isolated moiré flat bands. Moiré structures with more layers have not garnered much attention owing to the presence of additional bands that must be hybridized at low energy. This thesis will probe two graphene multilayer families: mixed dimensional moiré materials and double-twisted graphene multilayers. We find that the moiré can appreciably control the transport behavior of twisted graphene-graphite thin films and of an alternating twisted monolayer-trilayer-monolayer (t1+3+1) device. An inquiry of multilayered systems with higher band complexity is necessary in the search for superconductivity and novel correlated phenomena
Engineered plasma cells: a novel platform for long-term delivery of biologics to treat leukemia and other diseases
No full textThesis (Ph.D.)--University of Washington, 2023Advances in genome-engineering have enabled the generation of human plasma cells that secrete therapeutic proteins and are capable of long-term in vivo engraftment in humanized mouse models. To assist the clinical translation of engineered plasma cells (ePCs), we present three key studies evaluating: a) engineering approaches for optimized expression and secretion of non-immunoglobulin G (IgG)-like bispecific antibodies by human plasma cells to treat leukemias in vivo; b) a humanized mouse model to assess engraftment function and pharmacokinetics of adoptively transferred autologous ePC; and c) a novel B cell signaling BCR/Ab-screening method to evaluate highly expressed monoclonal antibodies for secretion by ePCs. We show that human ePCs expressing either anti-CD19 x anti-CD3 (blinatumomab) or anti-CD33 x anti-CD3 bispecific antibodies mediate T cell activation and direct T cell killing of specific primary human cell subsets and leukemia cell lines in vitro and in vivo. We demonstrate that the presence of autologous human hematopoietic cells in immunodeficient mice permits the establishment of a robust model for studying the in vivo biology and potential therapeutic benefit of long-lived human ePCs. Finally, we developed a B cell signaling-based method for the screening of BCRs for use as recombinant monoclonal antibody therapy and in engineered B cells and ePCs. Collectively, these findings support further development of ePCs for use as a durable system for the treatment of acute leukemias, and potentially other diseases
Supporting Sanctuary Efforts: Trends in Apprehension Data
No full textThis research project is a collaboration with two migrant justice organizations from Oregon, Pueblo Unido PDX (PU) and the Rural Organizing Project (ROP), who requested the assistance of UW researchers in analyzing data related to federal immigration enforcement in their state. In particular, these organizations were interested in knowing the answers to three major questions: Who is being targeted? What tactics are being used? And how does this vary over time and space