Reinforcement Learning using Augmented Neural Networks

Neural networks allow Q-learning reinforcement learning agents such as deep Q-networks (DQN) to approximate complex mappings from state spaces to value functions. However, this also brings drawbacks when compared to other function approximators such as tile coding or their generalisations, radial basis functions (RBF) because they introduce instability due to the side effect of globalised updates present in neural networks. This instability does not even vanish in neural networks that do not have any hidden layers. In this paper, we show that simple modifications to the structure of the neural network can improve stability of DQN learning when a multi-layer perceptron is used for function approximation.Comment: 7 pages; two columns; 4 figure

A Study of the Impact of Walker Lake on the North Branch of Middle Creek Using Metrics Generated by Diatom Biofilm Communities

Middle Creek is a tributary of the main stem of the Susquehanna River, and its watershed is confined mostly to Snyder County. The upper reaches of the stream are defined by two major branches, the North Branch and the West Branch, each of which is interrupted by a reservoir, Walker Lake and Faylor Lake, respectively. Walker Lake is an impoundment of a deep V-shaped valley and is 9-10 meters deep at the dam, which allows it to be stratified in the summer and winter. Summer stratification produces an anoxic hypolimnion, which is drawn off by the bottom outflow dam into the North Branch. During September of 2019 and 2020, the hypolimnion of Walker Lake became anoxic and its outflow below the dam had a strong odor of hydrogen sulfide with deposits of iron (III) oxide-hydroxide covering the cobbles and small boulders. The purpose of this preliminary investigation is to explore the impact of the bottom outflow below the dam and at sample sites downstream before and after fall turnover on the diatom biofilm communities and use them as proxies for the state of the stream. We examined five sites on the North Branch: above the lake (1.5 km above the lake), Walker Lake, below the dam at its outflow, a site 1.2 km downstream called Old Bridge, and a site 3 km from below the dam called Swift Run Confluence. Field measurements, using a YSI 556 multimeter, of pH, conductivity, and % oxygen saturation showed clear impacts when the lake was stratified but began to moderate following fall turnover. The loss of alkalinity and conductivity were particularly noticeable. The alkalinity decreased by 35% between the above site (2,350 µeq/L) and below the dam (1,514.4 µeq). Before turnover, at the below site, biofilm diatoms were scarcely found such that the phytoplankter, Asterionella formosa, which had been flushed from the lake, was the most abundant diatom species encountered from the stones collected at the site. Following turnover, however, the biofilm community reestablished itself and was dominated by Achnanthidium minutissumum in November 2019. Metrics based on diatom community analysis before and after turnover suggest the above lake site was impaired by agriculture (indices indicating high levels of sedimentation and nutrient runoff), but the reservoir did not function as a sediment or nutrient trap. Instead, the downstream sites showed higher impairment than the above lake site

FRONT International: Cleveland Triennial for Contemporary Art 2022 Economic Impact Study

FRONT International Cleveland Triennial for Contemporary Art 2022 public art exhibit ran from July 16 through October 2, 2022. The FRONT exhibit takes place every three years and this iteration, Oh, Gods of Dust and Rainbows, was displayed in Cleveland and Akron, OH at a variety of locations through partnerships with museums and other institutions in the region. This study uses a multi-regional input-output (I-O) model to estimate the effect of the exhibit on the economies of the Cleveland-Elyria-Mentor and Akron Metropolitan Statistical Areas. The economic impact consists of two components: impact of visitor spending and impact of the FRONT 2022 operating budget. The study also incorporates the results of a participant survey

Investing in the Middle

Middle Neighborhoods (MNs) are generally recognized for their safety, stability and affordability for residents. They also provide an important opportunity to give lower-income populations access to affordable housing and an overall higher quality of life, but the number of MNs is declining throughout the U.S. Recognizing these opportunities and challenges regarding MNs, the research team set out to fill in the existing knowledge gaps about which public policies and programmatic activities are effective at 1) stabilizing MNs and 2) providing equitable access for lower-income and marginalized populations to join and stay in MNs

Working Toward Human-Centered, Reparative Change Through Print Collection Development at the University of Denver

In 2014, the DU Libraries began to address a lack of work by and about the Cheyenne and Arapaho people in its collections, and moved toward reparative change in response to historical traumas suffered by Indigenous Peoples. The history of this work and its origins—which led to the creation of the Libraries’ Collection Diversification Task Force (CDTF) and now informs the Libraries’ collection development philosophy and operational inclusivity—are discussed in the “Developments Leading to the Collection Diversification Task Force” section of this chapter. Further on, the “Collection Diversification Task Force” section clarifies methodology, recommendations, and self-discovery on the part of librarians. Finally, “Reflections for Future Work” summarizes where collection diversification currently stands at DU Libraries and highlights the role of administrative support in encouraging this process to continue

Impact of Outpatient vs Inpatient ABSSSI Treatment on Outcomes: A Retrospective Observational Analysis of Medical Charts Across US Emergency Departments

Background The objective of this study was to characterize treatment of patients with acute bacterial skin and skin structure infections (ABSSSIs) and describe the association between hospital admission and emergency department (ED) visits or readmissions within 30 days after initial episode of care (IEC). Methods This was a retrospective, observational, cohort study of adults with ABSSSI who presented to an ED between July 1, 2012, and June 30, 2013. Patient, health care facility, and treatment characteristics, including unplanned ED visits or readmissions, were obtained through manual chart review and abstraction. Adjusted logistic regression analysis examined likelihood of all-cause unplanned ED visits or readmissions between admitted and nonadmitted patients. Results Records from 1527 ED visits for ABSSSI from 40 centers were reviewed (admitted, n = 578 [38%]; nonadmitted, n = 949 [62%]). Admitted patients were typically older (mean age, 52.2 years vs 43.0 years), more likely to be morbidly obese (body mass index \u3e 40 kg/m2; 17.3% vs 9.1%), and had more comorbidities (Charlson Comorbidity Index ≥ 4; 24.4% vs 6.8%) compared with those not admitted. In the primary analysis, adjusted logistic regression, controlling for comorbidities and severity of illness, demonstrated that there was a similar likelihood of all-cause unplanned ED visits or readmissions between admitted and nonadmitted patients (odds ratio, 1.03; 95% confidence interval, 0.74–1.43; P = .87). Conclusions ABSSSI treatment pathways leveraging outpatient treatment vs hospital admission support similar likelihood of unplanned 30-day ED visits or readmissions, an important clinical outcome and quality metric at US hospitals. Further research regarding the decision criteria around hospital admission to avoid potentially unnecessary hospitalizations is warranted