Master of Science

thesisSerum creatinine concentrations and estimated glomerular filtration rates (eGFR) are widely used for the evaluation of renal function. The Jaffe and enzymatic methods are the most common methods for creatinine measurement. The Jaffe method is commonly less expensive than enzymatic methods but may be more susceptible to interferences. Significant savings could be obtained if populations could be identified where the interference rate of the Jaffe method is acceptably low. The study objective was to compare creatinine and corresponding eGFR results from representative Jaffe and enzymatic creatinine methods in an outpatient population and determine the prevalence and magnitude of differences. This study analyzed 543 unique, randomly selected, outpatient samples. Samples were analyzed using both the Jaffe and enzymatic creatinine methods using an Abbott Architect c8000. eGFRs were calculated using the CKD-EPI and MDRD equations. Orthogonal (Deming) regression showed no significant difference between the two assays. The slope was 1.006 (95% CI: 0.998, 1.103) and the intercept was -0.005 (95% CI: -0.015, 0.006). The average difference (bias) was -0.007 mg/dL. The Bland- Altman limits of agreement (LOA) for the creatinine differences were -0.139 and 0.136 mg/dL. Of the CKD-EPI eGFR discrepancies, 3.1% resulted in a reclassification at the 60 mL/min/1.73m2 decision limit. The difference between the predicted and actual CKDEPI discordance at the 60 mL/min/1.73m2 decision limit was not statistically significant (χ! ! = -0.13, p=0.89). Of the MDRD eGFR discrepancies, 4.8% resulted in a iv reclassification at the 60 mL/min/1.73m2 decision limit. The difference between the predicted and actual MDRD discordance at the 60 mL/min/1.73m2 decision limit was not statistically significant (χ! ! = 0.31, p=0.76). Discrepancies in the CKD-EPI and MDRD eGFRs based on the Jaffe method did not result in a statistically significant increase in disease reclassifications at the 60 mL/min/1.73m2 decision limit in an outpatient population. The number of discordant eGFR results slightly varied by what discordance criteria was used. An equal number of discordances were observed with the MDRD and CKD-EPI equations when eGFR were based upon measurement error (217 of 543). When discordance criteria was based upon observed differences (Bland-Altman), the MDRD equation showed slightly more discordances (26 of 543) compared to the CKD-EPI (21 of 543). Studies are needed to characterize the relative rate of interference in additional populations

Energy Crop Land Use

A change from petroleum based energy sources has been in motion ever since the initiation of the renewable fuel standard starting in 2007. Dedicated cellulosic energy crops show potential for becoming a profitable solution to help bridge the growing demand for sustainable energy. Bioenergy crops can enhance ecosystem services in marginal lands, as shown in Figure 1

Knowledge Production and Social Roles in an Online Community of Emerging Occupation: A Study of User Experience Practitioners on Reddit

New occupations are emerging that have high job demand in the market, but lack a coherent body of disciplinary knowledge. For example, user experience (UX) design is an emerging occupation that has not been adequately supported by the traditional educational system. For learners beginning their undergraduate education, there is no concrete path to follow to become a UX professional, due to few UX-focused undergraduate academic programs. Online communities of practices have been recognized as important learning venues, even while institutions of formal education often lag behind in structuring knowledge production and distribution. However, little is known about how knowledge is generated and diffused in online communities in the context of emerging occupations with volatile knowledge boundaries. In this paper, we analyze knowledge production in relation to social roles in an online UX community. We show that knowledge production is highly distributed, involving the participation of community members of varied levels of experience. We discuss how online communities support the development of the UX occupation

Human-In-the-Loop for Bayesian Autonomous Materials Phase Mapping

Autonomous experimentation (AE) combines machine learning and research hardware automation in a closed loop, guiding subsequent experiments toward user goals. As applied to materials research, AE can accelerate materials exploration, reducing time and cost compared to traditional Edisonian studies. Additionally, integrating knowledge from diverse sources including theory, simulations, literature, and domain experts can boost AE performance. Domain experts may provide unique knowledge addressing tasks that are difficult to automate. Here, we present a set of methods for integrating human input into an autonomous materials exploration campaign for composition-structure phase mapping. The methods are demonstrated on x-ray diffraction data collected from a thin film ternary combinatorial library. At any point during the campaign, the user can choose to provide input by indicating regions-of-interest, likely phase regions, and likely phase boundaries based on their prior knowledge (e.g., knowledge of the phase map of a similar material system), along with quantifying their certainty. The human input is integrated by defining a set of probabilistic priors over the phase map. Algorithm output is a probabilistic distribution over potential phase maps, given the data, model, and human input. We demonstrate a significant improvement in phase mapping performance given appropriate human input

The Costs of Swapping on the Uniswap Protocol

We present the first in-depth empirical characterization of the costs of trading on a decentralized exchange (DEX). Using quoted prices from the Uniswap Labs interface for two pools -- USDC-ETH (5bps) and PEPE-ETH (30bps) -- we evaluate the efficiency of trading on DEXs. Our main tool is slippage -- the difference between the realized execution price of a trade, and its quoted price -- which we breakdown into its benign and adversarial components. We also present an alternative way to quantify and identify slippage due to adversarial reordering of transactions, which we call reordering slippage, that does not require quoted prices or mempool data to calculate. We find that the composition of transaction costs varies tremendously with the trade's characteristics. Specifically, while for small swaps, gas costs dominate costs, for large swaps price-impact and slippage account for the majority of it. Moreover, when trading PEPE, a popular 'memecoin', the probability of adversarial slippage is about 80% higher than when trading a mature asset like USDC. Overall, our results provide preliminary evidence that DEXs offer a compelling trust-less alternative to centralized exchanges for trading digital assets.Comment: 31 pages, 7 tables, 2 figure

Microearthquake Study of the Salton Sea Geothermal Field, California: Evidence of Stress Triggering

A digital network of 24 seismograph stations was operated from September 15, 1987 to September 30, 1988, by Lawrence Livermore National Laboratory and Unocal as part of the Salton Sea Scientific Drilling Project to study seismicity related to tectonics and geothermal activity near the drilling site. More than 2001 microearthquakes were relocated in this study in order to image any pervasive structures that may exist within the Salton Sea geothermal field. First, detailed velocity models were obtained through standard 1-D inversion techniques. These velocity models were then used to relocate events using both single event methods and Double-Differencing, a joint hypocenter location method. An anisotropic velocity model was built from anisotropy estimates obtained from well logs within the study area. During the study period, the Superstition wills sequence occurred with two moderate earthquakes of MS 6.2 and MS 6.6. These moderate earthquakes caused a rotation of the stress field as observed from the inversion of first motion data from microearthquakes at the Salton Sea geothermal field. Coulomb failure analysis also indicates that microearthquakes occurring after the Superstition Hills sequence are located within a region of stress increase suggesting stress triggering caused by the moderate earthquakes

Human dimensions in cyber operations research and development priorities.

Within cyber security, the human element represents one of the greatest untapped opportunities for increasing the effectiveness of network defenses. However, there has been little research to understand the human dimension in cyber operations. To better understand the needs and priorities for research and development to address these issues, a workshop was conducted August 28-29, 2012 in Washington DC. A synthesis was developed that captured the key issues and associated research questions. Research and development needs were identified that fell into three parallel paths: (1) human factors analysis and scientific studies to establish foundational knowledge concerning factors underlying the performance of cyber defenders; (2) development of models that capture key processes that mediate interactions between defenders, users, adversaries and the public; and (3) development of a multi-purpose test environment for conducting controlled experiments that enables systems and human performance measurement. These research and development investments would transform cyber operations from an art to a science, enabling systems solutions to be engineered to address a range of situations. Organizations would be able to move beyond the current state where key decisions (e.g. personnel assignment) are made on a largely ad hoc basis to a state in which there exist institutionalized processes for assuring the right people are doing the right jobs in the right way. These developments lay the groundwork for emergence of a professional class of cyber defenders with defined roles and career progressions, with higher levels of personnel commitment and retention. Finally, the operational impact would be evident in improved performance, accompanied by a shift to a more proactive response in which defenders have the capacity to exert greater control over the cyber battlespace

Attitudes, skills and use of evidence-based practice among UK osteopaths: A national cross-sectional survey

© 2018 The Author(s). Background: Evidence-based practice (EBP) is a clinical decision-making framework that supports quality improvement in healthcare. While osteopaths are key providers of musculoskeletal healthcare, the extent to which osteopaths engage in EBP is unclear. Thus, the aim of this cross-sectional study was to investigate UK osteopaths' attitudes, skills and use of EBP, and perceived barriers and facilitators of EBP uptake. Methods: UK-registered osteopaths were invited to complete the Evidence-Based Practice Attitude and Utilisation Survey (EBASE) online. Results: Of the 5200 registered osteopaths in the UK, 9.9% (517/5200) responded to the invitation, and 7.2% (375/5200) completed the EBASE (< 20% incomplete answers). The demographic characteristics of the survey sample were largely similar to those of the UK osteopathy workforce. The osteopaths reported overall positive attitudes towards EBP, with most agreeing that EBP improves the quality of patient care (69.3%) and is necessary for osteopathy practice (76.5%). The majority reported moderate-level skills in EBP, and most (80.8%) were interested in improving these skills. Participating osteopaths typically engaged in EBP activities 1-5 times over the last month. Barriers to EBP uptake included a lack of time and clinical evidence in osteopathy. Main facilitators of EBP included having access to online databases, internet at work, full-text articles, and EBP education materials. Conclusions: UK osteopaths were generally supportive of evidence-based practice, had moderate-level skills in EBP and engaged in EBP activities infrequently. The development of effective interventions that improve osteopaths' skills and the incorporation of EBP into clinical practice should be the focus of future research

‘Proclaiming it to Greeks and Natives, along the rows of the chequer-board': readers and viewers of Greek, Latin and Demotic Acrostich inscriptions

Hellenistic and Roman acrostich inscriptions are usually full of verbal and visual clues, which point the reader in the direction of the ‘hidden message’ contained in the vertical lines of the text. The authors of such inscriptions want their audiences to appreciate the skill that has gone into their composition. There are several complementary ways in which the presence of an acrostich might be signalled to the reader or viewer and their attention directed towards it. These include direct verbal statements, or more subtle allusions, within the text of the inscription. But, even without having read its text, the viewer of an inscription containing a ‘hidden message’ is often immediately aware that some kind of wordplay is at work. Acrostichs, palindromes and various kinds of word square are all graphically striking, or their appearance may be enhanced to make them more so. Regular spacing, the repetition of the acrostich in a separate column and the use of painted or incised grids are all ways in which the layout of the text on the stone can invite the viewer to play a word game. In some cases, as I will argue in this paper, acrostich makers envisaged—even intended—the participants in this game to include the illiterate as well as the literate