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Quaternary ammonium compounds (QACs), a large class of chemicals that includes high production volume substances, have been used for decades as antimicrobials, preservatives, and antistatic agents, and for other functions in cleaning, disinfecting, personal care products, and durable consumer goods. QAC use has accelerated in response to the COVID-19 pandemic and the banning of 19 antimicrobials from several personal care products by the US Food and Drug Administration in 2016. Studies conducted before and after the onset of the pandemic indicate increased human exposure to QACs. Environmental releases of these chemicals have also increased. Emerging information on adverse environmental and human health impacts of QACs is motivating a reconsideration of the risks and benefits across the life cycle of their production, use, and disposal. This paper presents a critical review of the literature and scientific perspective developed by a multidisciplinary, multi-institutional team of authors from academia, governmental, and nonprofit organizations. The review evaluates currently available information on the ecological and human health profile of QACs and identifies multiple areas of potential concern. Adverse ecological effects include acute and chronic toxicity to susceptible aquatic organisms, with concentrations of some QACs approaching levels of concern. Suspected or known adverse health outcomes include dermal and respiratory effects, developmental and reproductive toxicity, disruption of metabolic function such as lipid homeostasis, and impairment of mitochondrial function. QACs’ role in antimicrobial resistance has also been demonstrated. In the US regulatory system, how a QAC is managed depends on how it is used, for example, in pesticides or personal care products. This can result in the same QACs receiving different degrees of scrutiny depending on the use and the agency regulating it. Further, the EPA’s current method of grouping QACs based on structure, first proposed in 1988, is insufficient to address the wide range of QAC chemistries, potential toxicities, and exposure scenarios. Consequently, exposures to common mixtures of QACs and from multiple sources remain largely unassessed. Some restrictions on the use of QACs have been implemented in the US and elsewhere, primarily focused on personal care products. Assessing the risks posed by QACs is hampered by their vast structural diversity and a lack of quantitative data on exposure and toxicity for the majority of these compounds. This review identifies important data gaps and provides research and policy recommendations for preserving the utility of QAC chemistries while also seeking to limit adverse environmental and human health effects. 

To succeed in the 21stcentury, students need to acquire skills that are critical to the workforce such as collaboration, social skills, and technology literacy (World Economic Forum, 2016). Individuals with disabilities (D) must develop the same skills as their peers without disabilities. Unfortunately, college students with disabilities often find computing courses frustrating and are more vulnerable to lower academic self-concept, academic challenges, and disability stigma (Kim & Kutscher, 2021). Although computing disciplines often provide good job opportunities, Students with D who enrolled in computing courses are especially at risk of falling behind and dropping out of introductory programming courses (Richman et al., 2014). To address the problem, we examined the use of pair programming, a collaborative approach to programming, as a pedagogic method to improve students with disabilities’ attitudes toward programming in undergraduate computer courses. There is a need to study effective instructional approaches that can facilitate learning and improve the outcomes of students with D. 

Recent advances in the blockchain research have been made in two important directions. One is refined resilience analysis utilizing game theory to study the consequences of selfish behavior of users (miners), and the other is the extension from a linear (chain) structure to a non-linear (graphical) structure for performance improvements, such as IOTA and Graphcoin. The first question that comes to mind is what improvements that a blockchain system would see by leveraging these new advances. In this paper, we consider three major properties for a blockchain system: α-partial verification, scalability, and finality-duration. We establish a formal framework and prove that no blockchain system can achieve ?-partial verification for any fixed constant ?, high scalability, and low finality-duration simultaneously. We observe that classical blockchain systems like Bitcoin achieves full verification (α=1) and low finality-duration, Ethereum 2.0 Sharding achieves low finality-duration and high scalability. We are interested in whether it is possible to partially satisfy the three properties. 

This paper is the report on the findings of a three-year study conducted in undergraduate computer science courses. It also describes the changes made to deal with COVID-19 during the summer and fall of 2020. We collected data on over 800 students with approximately 35 students identified as having learning disabilities (LD). These students were not professional programmers in a computer science department; rather, they were students from a Business College. Our preliminary results show that pair programming improved (a) teamwork and communication between the pairs; (b) confidence in students; and (c) comprehension and learning for all students. Thus, our preliminary results indicate that pair programming improved everyone’s performance. Educators should consider the importance of collaboration with other disciplines when creating inclusive environments for students with disabilities. 

Peer learning through pair programming is a type of collaborative learning that involves students working in pairs to discuss computer programming concepts or develop codes to solve problems. The Zoom breakout room method is applied to teach pair programming in a virtual classroom during the COVID-19 environment. By facilitating pair programming in a virtual learning environment, we gained valuable experience in promoting collaborative learning, active learning, and problem-based learning activities in a cloud setting.