Development of a high-voltage laser triggered switch facility including initial optical and electrical diagnostics

2019 Fall.Includes bibliographical references.Pulsed power programs have been part of the United States strategic plan to address the nation's energy and defense needs since the 1960s. With escalating energy demand, one of the greatest challenges of our time is to develop clean and reliable energy sources with controlled fusion being an exciting and favorable candidate. Developing this technology has been an arduous and taxing effort with a breakthrough (supposedly) coming just around the corner for decades. Arguably, one of the leading testbeds for fusion research is Sandia National Laboratories (SNL) Z machine which is part of SNL's pulsed power program. The Z machine can create fusion-like conditions and allows the global research community to investigate pathways forward to a viable fusion reactor. Integral to developing future pulsed power technology and the next Z-pinch style machines, high voltage spark gap switches are an active research area and the focus of this thesis. Partnering with SNL this body of work details our efforts to develop a high voltage laser triggered switch facility at Colorado State University (CSU). We present the design and development of the Pulsed Power and Plasma Science Center (P3SC) along with preliminary diagnostic measurements of a millimeter gap length optically accessible high-voltage laser triggered switch (HV-LTS). The current thrust of the P3SC laboratory is to investigate switch closure plasma characteristics associated with recently discovered gaps in the Tom Martin switch model which describes temporal plasma channel resistance of these HV-LTSs. Basic background and theory of the Martin model are discussed including laying out two key assumptions we believe are related to the error recently found. Specifically, radial switch closure plasma channel growth fits an Atk trend (A and K are constants), and constant electrical conductivity are assumed both spatially and temporally. Considering extremely high voltages and nanosecond timescales of switch closure, direct measurements of these characteristics are extremely difficult. Therefore, we present contact and non-contact optical measurements that can be utilized to help inform the assumptions laid out herein. Specifically, a current viewing resistor (CVR) that was designed to withstand peak energies involved during switch closure was used to directly measure voltage, and subsequent current, associated with switch closure. CVR measurements along with triggering data allowed for determination of essential electrical characteristics common for HV-LTS technology. With knowledge of these macroscopic electrical characteristics a non-contact optical measurement scheme was devised to investigate switch closure plasma's more closely, including schlieren imaging and optical emission spectroscopy (OES). Specifically, temporal mapping of the switch closure plasma channel through direct imaging allows for characterization of radial growth (first assumption), and OES can be used to calculate electron temperatures which can be related to the electrical conductivity (second assumption). Given this backdrop we present key electrical characteristics on an optically accessible HV-LTS including: self-break behavior, switch run time, jitter, and equivalent circuit resistance and inductance. Further, radial plasma growth is measured (from intensified camera images) and found to agree with the Martin model assumptions, albeit with variability yielding a potential error in calculated resistance of ~15%. OES of switch closure plasmas are also recorded and show the spectra to be dominated by continuum at early times with emission lines becoming visible at ~200 ns after a 25 kV shot and ~500 ns after a 50 kV shot. This data, to the best of the author's knowledge, represents the first publication of HV-LTS emission spectra. With this data we have shown that the electrical conductivity assumption is the most likely cause of the error found in the Martin model. Continued investigation is warranted, and a more robust optical measurement like Thomson scattering is being considered to inform the Martin model and more generally the next generation of pulsed power technolog

Development of a Rooftop Collaborative Experimental Space through Experiential Learning Projects

The Solar, Water, Energy, and Thermal Laboratory (SWEAT Lab) is a rooftop experimental space at the University of Texas at Austin built by graduate and undergraduate students in the Cockrell School of Engineering. The project was funded by the Texas State Energy Conservation Office and the University’s Green Fee Grant, a competitive grant program funded by UT Austin tuition fees to support sustainability-related projects and initiatives on campus. The SWEAT Lab is an on-going experiential learning facility that enables engineering education by deploying energy and water-related projects. To date, the lab contains a full weather station tracking weather data, a rainwater harvesting system and rooftop garden. This project presented many opportunities for students to learn first hand about unique engineering challenges. The lab is located on the roof of the 10 story Engineering Teaching Center (ETC) building, so students had to design and build systems with constraints such as weight limitations and wind resistance. Students also gained experience working with building facilities and management for structural additions, power, and internet connection for instruments. With the Bird’s eye view of UT Austin campus, this unique laboratory offers a new perspective and dimension to applied student research projects at UT Austin.Cockrell School of Engineerin

Exploring attention-based explanations for some violations of Hick’s law for aimed movements

Choice reaction time generally increases linearly with the logarithm of the number of potential stimulus–response alternatives, a regularity known as Hick’s law. Two apparent violations of this generalization, which have been reported for aimed eye movements (Kveraga, Boucher, & Hughes, Experimental Brain Research, 146, 307–314, 2002), and arm movements (Wright, Marino, Belovsky, & Chubb, Experimental Brain Research, 179, 475–496, 2007), occurred when the indicator stimulus was an abrupt change at the location that was the target of the to-be-made movement. We report two experiments that examined and rejected the hypothesis that these abrupt-onset indicator stimuli triggered a shift in exogenous attention and that this led to unusually small uncertainty effects. Each experiment compared this indicator stimulus with a single alternative: Experiment 1 tested an indicator stimulus at all locations other than the target; Experiment 2 tested a central pointer to the target. Neither alternative led to an uncertainty effect for pointing responses that was of the size typically observed for other responses using the same stimuli

Enzymatic semisynthesis of insulin specifically labelled with tritium at position B-30

We have synthesized porcine insulin labelled with tritium at position B-30 using enzyme-catalysed formation of a peptide bond. The resulting insulin derivative has the label in the expected position and is biologically active. We have tested our procedure to prepare batches up to 50μCi of tritiated insulin at a specific radioactivity of up to 1.14 Ci/mmo

Knowledge, attitudes, and reported practices among obstetrician-gynecologists in the USA regarding antibiotic prescribing for upper respiratory tract infections.

BACKGROUND: Knowledge, attitudes, and practices regarding antibiotic prescribing for upper respiratory tract infections (URIs) have not been well described among obstetrician-gynecologists (OB/GYNs). This information is useful for determining whether an OB/GYN-specific program promoting appropriate antibiotic use would significantly contribute to the efforts to decrease inappropriate antibiotic use among primary care providers. METHODS: An anonymous questionnaire asking about the treatment of URIs was sent to 1031 obstetrician-gynecologists. RESULTS: The overall response rate was 46%. The majority of respondents (92%) were aware of the relationship between antibiotic use and antibiotic resistance, and respondents estimated that 5% of their patients had URI symptoms at their office visits. Overall, 56% of respondents reported that they would prescribe an antibiotic for uncomplicated bronchitis and 43% for the common cold. OB/GYNs with the fewest years of experience were less likely than those with the most years of experience to report prescribing for uncomplicated bronchitis (Odds ratio (OR) 0.46, 95% confidence interval (CI) 0.23 to 0.91) or the common cold (OR 0.44, CI 0.22 to 0.89). The majority of respondents (60%) believed that most patients wanted an antibiotic for URI symptoms, with male OB/GYNs being more likely than female OB/GYNs (OR 2.1, CI 1.2 to 3.8) to hold this belief. Both male OB/GYNs (OR 1.9, CI 1.1 to 3.4) and rural practitioners (OR 2.1, CI 1.1 to 4.0) were more likely to believe that it was hard to withhold antibiotics for URI symptoms because other physicians prescribe antibiotics for these symptoms. OB/GYNs who believed that postgraduate training prepared them well for primary care management were more likely than those who did not (OR 2.1, CI 1.1 to 4.2) to believe that they could reduce antibiotic prescribing without reducing patient satisfaction. CONCLUSION: Multiple demographic factors affect attitudes and reported practices regarding antibiotic prescribing. However, in view of the low proportion of office visits for URIs, an OB/GYN-specific program is not warranted

INFLUENCE OF FUNDING ACTIVITY AS ACOMPONENT OF SANITATION FINANCING PROGRAM ON COMMUNITY LIVELIHOOD IN URBAN INFORMAL SETTLEMENT OF OBUNGA, KISUMU COUNTY, KENYA

The study sought to investigate the influence of funding activities as a component of sanitation financing programme on community livelihood in urban informal settlements of Kisumu County, Kenya. The purpose of the study was to assess the influence of funding activities on community livelihood in urban informal settlement of Obunga, Kisumu County Kenya. The study adopted inferential analysis and descriptive survey research design with sample size of 384 households and 10 key informants. The study sample was obtained through stratified simple random, and purposive sampling strategies. Quantitative data was analysed using means, standard deviations, frequencies, and percentages. Qualitative data was transcribed and analysed in emergent themes and sub-themes. Results were interpreted and requisite recommendations made. According to the results, there is a statistically significant positive correlation between funding activities and community livelihood (p < 0.05). Coefficient of determination showed that funding activities accounted for 24.1% of the changes in community livelihood. Findings from the study established that there was statistically significant correlation between funding activities as a component of sanitation financing program and community livelihood. The study recommends the funding activity should be sustained in the sanitation financing program for purposes of improving community livelihood .The study concluded that investing in funding activities of sanitation financing programme in Obunga urban informal settlement of Kisumu County, Kenya has a positive influence on community livelihood. The study calls for further research on the influence of funding activities as a component of sanitation financing program on community livelihood using other predictors of community livelihood as well as influence of sanitation financing program on community livelihood; a comparison between formal and informal urban settlements.  Article visualizations

Multiple Imputation of Missing Race and Ethnicity in CDC COVID-19 Case-Level Surveillance Data

The COVID-19 pandemic has resulted in a disproportionate burden on racial and ethnic minority groups, but incompleteness in surveillance data limits understanding of disparities. CDC’s case-based surveillance system contains most COVID-19 cases in the United States. Data analyzed in this paper contain COVID-19 cases with case-level information through September 25, 2020, which represent 70.9% of all COVID-19 cases reported to CDC during the period. Case-level surveillance data are used to investigate COVID-19 disparities by race/ethnicity, sex, and age. However, demographic information on race and ethnicity is missing for a substantial percentage of COVID-19 cases (e.g., 35.8% and 47.2% of cases analyzed were missing race and ethnicity information, respectively). Our goal in this study was to impute missing race and ethnicity to derive more accurate incidence and incidence rate ratio (IRR) estimates for different racial and ethnic groups, and evaluate the results from imputation compared to complete case analysis, which involves removing cases with missing race/ethnicity information from the analysis. Two multiple imputation (MI) models were developed. Model 1 imputes race using six binary race variables, and Model 2 imputes race as a composite multinomial variable. Our evaluation found that compared with complete case analysis, MI reduced biases and improved coverage on incidence and IRR estimates for all race/ethnicity groups, except for the Non-Hispanic Multiple/other group. Our research highlights the importance of supplementing complete case analysis with additional methods of analysis to better describe racial and ethnic disparities. When race and ethnicity data are missing, multiple imputation may provide more accurate incidence and IRR estimates to monitor these disparities in tandem with efforts to improve the collection of race and ethnicity information for pandemic surveillance

Fatal Outcome of Disseminated Strongyloidiasis despite Detectable Plasma and Cerebrospinal Levels of Orally Administered Ivermectin

Strongyloides stercoralis affects over 100 million people worldwide. Those people most susceptible to infection are those with an immunocompromising condition, such as cancer or human immunodeficiency virus (HIV). Local disease may spread throughout the body of the host, causing a condition termed disseminated strongyloidiasis. Standard treatment for Strongyloides stercoralis infection is oral ivermectin. We describe a patient with chronic lymphocytic leukemia diagnosed with disseminated strongyloidiasis two weeks after initial presentation. After repeated dosing of oral ivermectin with no clinical response, serum and cerebral spinal fluid (CSF) concentrations of ivermectin were measured to assess absorption. The peak serum concentration of 49.3 ng/mL correlated with a CSF concentration of 0.14 ng/mL. Despite these concentrations, the patient eventually succumbed to multi-system organ failure. We discuss the reasons for treatment failure and explore the utility of measuring ivermectin concentrations

FOXA1 mutations alter pioneering activity, differentiation and prostate cancer phenotypes.

Mutations in the transcription factor FOXA1 define a unique subset of prostate cancers but the functional consequences of these mutations and whether they confer gain or loss of function is unknown1-9. Here, by annotating the landscape of FOXA1 mutations from 3,086 human prostate cancers, we define two hotspots in the forkhead domain: Wing2 (around 50% of all mutations) and the highly conserved DNA-contact residue R219 (around 5% of all mutations). Wing2 mutations are detected in adenocarcinomas at all stages, whereas R219 mutations are enriched in metastatic tumours with neuroendocrine histology. Interrogation of the biological properties of wild-type FOXA1 and fourteen FOXA1 mutants reveals gain of function in mouse prostate organoid proliferation assays. Twelve of these mutants, as well as wild-type FOXA1, promoted an exaggerated pro-luminal differentiation program, whereas two different R219 mutants blocked luminal differentiation and activated a mesenchymal and neuroendocrine transcriptional program. Assay for transposase-accessible chromatin using sequencing (ATAC-seq) of wild-type FOXA1 and representative Wing2 and R219 mutants revealed marked, mutant-specific changes in open chromatin at thousands of genomic loci and exposed sites of FOXA1 binding and associated increases in gene expression. Of note, ATAC-seq peaks in cells expressing R219 mutants lacked the canonical core FOXA1-binding motifs (GTAAAC/T) but were enriched for a related, non-canonical motif (GTAAAG/A), which was preferentially activated by R219-mutant FOXA1 in reporter assays. Thus, FOXA1 mutations alter its pioneering function and perturb normal luminal epithelial differentiation programs, providing further support for the role of lineage plasticity in cancer progression