Browsing by Subject "performance"

Now showing 1 - 9 of 9
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    Assessing the performance of ultrasound imaging systems using images from relatively high‐density random spherical void phantoms: A simulation study
    (Wiley, 2022-02) Holland, Mark R.; Radiology & Imaging Sciences, School of Medicine
    Background The development of clinically meaningful, objective, and quantitative methods for assessing the performance of ultrasound imaging systems represents a continuing area of interest. One approach has been to image phantoms with randomly distributed spherical voids. Purpose The objectives of this study were: (1) to explore the potential of using relatively high-volume fraction random spherical void (RSV) phantoms as an approach for quantitatively assessing the performance of ultrasound imaging systems; (2) to identify potential metrics that can be used to provide quantitative assessments of images obtained from relatively high-volume fraction RSV phantoms; and (3) to demonstrate changes in the quantitative metrics that can occur as image features are degraded. Methods A series (10 each) of computer-simulated RSV phantoms with a range of RSV volume fractions (0.05, 0.15, and 0.25) were generated. To determine the number of image planes necessary to provide robust measurements, a series of consecutive planes (ranging from 1 to 150) within each type of simulated phantom were analyzed. The observed circular cross-section radii histogram distributions (representing the intersection of each plane with the local distribution of spherical voids) were compared with the theoretical histogram distribution. Simulated phantom images were produced by adding speckle and degradation of imaging system performance was modeled by averaging 1 to 9 neighboring planes to represent increasing elevation plane thicknesses. Quantification of the performance of the imaging system was determined by measuring the: (1) mean number of circular cross-sections detected per image frame; (2) mean fractional area of circular cross-sections detected per image frame; (3) agreement of observed circular cross-section radii histogram distribution with the theoretical distribution (Chi-square statistic); and (4) contrast and contrast-to-noise ratio as a function of observed circular cross-section radius. Results Results suggest that analyses of a sufficient number of image planes (providing over approximately 3000 total circular cross-sectional areas) provides excellent agreement between the observed and theoretical histogram distributions (mean Chi-square < 0.004). For the 0.15 volume fraction series of simulated RSV phantoms, using 150 image plane analyses, phantom images show decreasing mean number of circle cross-sections detected per frame (31.5 ± 0.3, 28.4 ± 0.3, 28.2 ± 0.3, 26.3 ± 0.3, and 25.3 ± 0.3); decreasing mean fractional area of circle cross-sections per frame (0.157 ± 0.002, 0.133 ± 0.001, 0.133 ± 0.001, 0.111 ± 0.001, and 0.108 ± 0.001); and a decreasing agreement with the theoretical histogram distribution of radii (Chi-square values: 0.070 ± 0.004, 0.140 ± 0.005, 0.149 ± 0.007, 0.379 ± 0.011, and 0.518 ± 0.010) for 1, 3, 5, 7, and 9 plane averages, respectively. Contrast and contrast-to-noise measurements as a function of observed circular cross-section radius also demonstrate marked changes with simulated image degradation. Conclusions Results of this simulation study suggest that analyses of images obtained from relatively high-density RSV phantoms may offer a promising approach for assessing ultrasound imaging systems. The proposed measurements appear to provide reproducible, robust, quantitative metrics that can be compared with corresponding theoretical values to provide quantifiable, objective metrics of imaging system performance.
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    Association between Medical Student Grit and United States Medical Licensing Examination Performance
    (2020-03-06) Anton, Nicholas E.; Huffman, Elizabeth; Choi, Jennifer
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    Effect of Low Dose of Amphetamine on Thermoregulation System and Performance of Rats Running on Treadmills
    (Office of the Vice Chancellor for Research, 2015-04-17) Behrouzvaziri, Abolhassan; Molkov, Yaroslav; Morozova, Ekaterina; Yoo, Yeonjoo; Zaretskaia, Maria; Zaretsky, Dmitry
    Amphetamine has been used widely as a performance-enhancing drug among athletes. There are numerous reports showing that low dose of amphetamine increases one’s performance by suppressing sensations of fatigues. However, a little has been known about the mechanism by which such an effect of amphetamine is caused. The goal of this study was to investigate how a low dose of amphetamine changed the duration and the capacity of running in rats by studying thermoregulation system of rats running on treadmills with experimental results and a mathematical model. 12 rats were separated into two groups of 6 and rats in the experimental group were injected with 2mg/kg of amphetamine and ones in the control group were injected with saline. Then each rat in both groups ran on a treadmill at the room temperature (25°􀜥) while the speed and the incline of the treadmill were increased stepwise in every 3 minutes. The running time of individual rats were determined by their ability of keeping up with the intensity of running and the core body temperatures and the oxygen consumptions (􀜸􀜱􀬶)of rats were recorded during the experiments. Then a mathematical model was constructed to describe rates of temperature changes in the core and muscles by quantifying the heat dissipations and heat productions using 􀜸􀜱􀬶. Modeling revealed that amphetamine increases the heat dissipation in the core body, which slowed down the core temperature increase. Therefore rats injected with amphetamine were kept their core temperatures below approximately 40 °C for longer time, at which both groups were unable to run anymore. Additionally, the fact that the core temperature at the end of run was not significantly different between two groups, while muscle temperature was significantly different, suggests that the indicator of running capacity was the core temperature, rather than the muscle temperature. Finally, the level of overheating in muscles for the amphetamine group was severe enough to cause damages in muscles.
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    Gender and Performance in Public Organizations: A Research Synthesis and Research Agenda
    (Taylor & Francis, 2021) Park, Sanghee
    This study examines the variations among empirical findings of gender effects on performance in public organizations; and identifies and discusses areas to be addressed in future research. The meta-analysis using 72 studies published between 1999 and 2017 presents evidence that greater representation of women in the workforce and more women in leadership roles have a positive effect on public organization performance. Study characteristics such as policy/service areas, geographical context, and time frames of the study affect the findings of gender effects, while the variance in measurement strategies and publication status do not make a difference in empirical evidence.
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    Managerial Ability and Income Smoothing
    (American Accounting Association, 2019-10-11) Baik, Bok; Choi, Sunhwa; Farber, David B.; Kelley School of Business
    In this study, we investigate whether managerial ability is related to income smoothing and, if so, whether smoothing associated with managerial ability improves the informativeness of earnings and stock prices about future performance. Using a large sample of firms, we find that managerial ability is positively related to smoothing. More importantly, we show that high-ability managers incorporate more forward-looking information about cash flows into current earnings through smoothing, thereby enhancing earnings informativeness. We also find that smoothing associated with high-ability managers improves stock price informativeness about future cash flows. Our study should be of interest to researchers, practitioners, and others concerned with understanding the determinants and usefulness of smoothing.
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    Nonprofit Performance: Accounting for the Agency of Clients
    (Sage, 2015-10) Benjamin, Lehn M.; Campbell, David; School of Philanthropy
    Performance is a key concern for nonprofits providing human services. Yet our understanding of what drives performance remains incomplete. Existing outcome measurement systems track the programmatic activities staff complete and the extent to which participants respond in programmatically intended ways. However, clients do not just receive services and respond as intended and staff do not simply complete program activities. Drawing on a data set of 47 interviews with frontline staff in eight human service nonprofits, we show how frontline staff work in a partnership with clients to set an agenda for change and achieve desired results. We call this co-determination work and argue that it represents a critical and often neglected dimension of nonprofit performance.
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    Parent-Perceived Effectiveness of the Occupational Performance Coaching Model: A Doctoral Capstone Project
    (2022-05-02) Withrow, Grace E.; Petrenchik, Terry; Department of Occupational Therapy, School of Health and Human Sciences; Frigo, Mariann
    The ultimate purpose of this capstone project was to identify an evidence-based method that helps to close the gap between the number of children who need therapy services and the number of children who receive them. A formal needs assessment was conducted, confirming that this gap is real and exists due to a variety of factors—lack of parent involvement, education, and in-home carryover being at the forefront. As a result, this study aimed to examine the parents’ opinions on the effectiveness of implementing a coaching model, specifically the Occupational Performance Coaching (OPC) model. A thorough literature review was conducted on this model, identifying its structure and strengths. The goal of the coaching model was to empower parents to be autonomous and confident when working with their children at home. This model was implemented with 9 participant families during a 6-week period in which in-person services were delivered to the child with both the therapist and parent present. The therapist coached the parent throughout the session, exchanging information and encouraging independent problem-solving apart from therapy. After the 6-week period, all participant families were asked to take the post-experiential survey and 8 completed it. The responses were uniformly positive and supported the premise and use of the OPC through three major themes, identified and coded using directed qualitative content analysis. These themes were program value, expectation setting, and benefits including empowerment through knowledge acquisition and skill acquisition. The project was deemed mutually beneficial by each the student and the capstone site and had an overall positive impact on the profession of occupational therapy.
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    The Scale of Mission-Embeddedness as a Nonprofit Revenue Classification Tool: Different Earned Revenue Types, Different Performance Effects
    (SAGE, 2018-08-01) Levine Daniel, Jamie; Kim, Mirae; School of Public and Environmental Affairs
    Nonprofits rely on earned revenue to remain sustainable. Prior studies have generally aggregated all earned revenue and evaluated its influence on financial sustainability. Our study takes a different approach, assessing the effects of three different types of earned revenue on an immediate program outcome. We use Cultural Data Project data from 2,000 arts and culture nonprofits from 2004-2012. We find that embedded and integrated earned revenue are linked to better program outcomes while external earned revenue is related to poorer program outcomes. Results depend on type (performing vs. visual arts) and funding structure (donative vs. commercial).
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    Supply Chain Power Configurations and their Relationship with Performance
    (Wiley, 2017) Huo, Baofeng; Flynn, Barbara B.; Zhao, Xiande; Kelley School of Business
    In order to lay the foundation for the study of supply chain power, we study power configurations at the level of interlocking power dyads (IPDs), viewing the simultaneous effect of upstream and downstream power. We build on four key constructs: dependence asymmetry (resource dependence theory), joint dependence (embeddedness perspective), power type differential (based on French and Raven, 1959) and power source asymmetry. We examine the research question of what the relationship is between IPDs and the focal firm's operational performance, developing hypotheses based on the dependence asymmetry, joint dependence, power type differential and power source asymmetry of theoretical IPDs. A survey of over 600 respondents in China was used to collect data on focal firm perceptions of upstream and downstream power, with cluster analysis yielding eight IPDs. Inferential analysis revealed the importance of joint dependence, dependence asymmetry, power type differential and power source asymmetry to the operational performance of the focal firm.