Generalized model of blockage in particulate flow limited by channel carrying capacity

We investigate stochastic models of particles entering a channel with a random time distribution. When the number of particles present in the channel exceeds a critical value $N$, a blockage occurs and the particle flux is definitively interrupted. By introducing an integral representation of the $n$ particle survival probabilities, we obtain exact expressions for the survival probability, the distribution of the number of particles that pass before failure, the instantaneous flux of exiting particle and their time correlation. We generalize previous results for $N=2$ to an arbitrary distribution of entry times and obtain new, exact solutions for $N=3$ for a Poisson distribution and partial results for $N\ge 4$.Comment: 13 pages, 9 figure

Conceptualisation and experiences of engaged citizenship as critical consciousness, transformative education and mutual joy: An autoethnography

In recent years, higher education institutions globally and in South Africa have begun to focus more on the educational potential of community-university engagement. As a result, many institutions of higher learning have been reimagining and debating the terms used to describe the engagement between students, academic staff and their community partners. At Rhodes University in Makhanda, there has been an active change in terminology, with previous “volunteerism” programmes renamed “engaged citizenship” opportunities. This article’s authors are current staff members and previous students at Rhodes University, whose university experiences were shaped by their involvement in the Rhodes University Community Engagement (RUCE) Division. Using an autoethnographic style, they reflect on their experiences as volunteers/engaged citizens. These stories and reflections serve to highlight how the term engaged citizenship better encapsulates the nature of the involvement of students who are actively involved in their communities: where these community engagement spaces provide mutual benefit and mutual joy, deep learning and platforms for individuals to direct their agency to socially just ends. Ultimately, these narratives aim to illustrate the deeply personal ways in which the practice of engaged citizenship has shaped the authors’ own growth and generated the holistic and transformative educational experience for which higher education institutions strive

CARTE: An Observation Station to Regulate Activity in a Learning Context

This chapter discusses the introduction of a new concept called "regulation" into a use model, which is part of a theoretical observation model called trace-based system (TBS). This concept defines a retroaction mechanism in an observation station. We present the results of experiments, in a learning context, with a prototype observation station called Collection, activity Analysis and Regulation based on Traces Enriched (CARTE)

Use of Electronic Health Records to Manage Tobacco Screening and Treatment in Rural Primary Care

Researchers at the Maine Rural Health Research Center, University of Southern Maine examined whether the use of electronic health records by rural primary care physicians facilitates their use of best practices in addressing tobacco dependence. The study used the National Ambulatory Medicare Care Survey (2012-2015) to explore how rurality and use of tobacco-related electronic health record functions were related to smoking status documentation and cessation treatment at adult primary care visits. Rural-urban comparisons were also examined. The authors conclude that rural primary care physicians were at least as successful as their urban counterparts in leveraging electronic health records to enhance tobacco-related services, and that opportunities exist to expand cessation treatment in rural primary care. FMI: Jean Talbot, [email protected]

Photochemistry in the arctic free troposphere: NOx budget and the role of odd nitrogen reservoir recycling

The budget of nitrogen oxides (NOx) in the arctic free troposphere is calculated with a constrained photochemical box model using aircraft observations from the Tropospheric O3 Production about the Spring Equinox (TOPSE) campaign between February and May. Peroxyacetic nitric anhydride (PAN) was observed to be the dominant odd nitrogen species (NOy) in the arctic free troposphere and showed a pronounced seasonal increase in mixing ratio. When constrained to observed acetaldehyde (CH3CHO) mixing ratios, the box model calculates unrealistically large net NOx losses due to PAN formation (62pptv/day for May, 1-3km). Thus, given our current understanding of atmospheric chemistry, these results cast doubt on the robustness of the CH3CHO observations during TOPSE. When CH3CHO was calculated to steady state in the box model, the net NOx loss to PAN was of comparable magnitude to the net NOx loss to HNO3 (NO2 reaction with OH) for spring conditions. During the winter, net NOx loss due to N2O5 hydrolysis dominates other NOx loss processes and is near saturation with respect to further increases in aerosol surface area concentration. NOx loss due to N2O5 hydrolysis is sensitive to latitude and month due to changes in diurnal photolysis (sharp day-night transitions in winter to continuous sun in spring for the arctic). Near NOx sources, HNO4 is a net sink for NOx; however, for more aged air masses HNO4 is a net source for NOx, largely countering the NOx loss to PAN, N2O5 and HNO3. Overall, HNO4 chemistry impacts the timing of NOx decay and O3 production; however, the cumulative impact on O3 and NOx mixing ratios after a 20-day trajectory is minimal. © 2003 Elsevier Science Ltd. All rights reserved

Photochemistry in the arctic free troposphere: Ozone budget and its dependence on nitrogen oxides and the production rate of free radicals

Abstract. Local ozone production and loss rates for the arctic free troposphere (58–85 ◦ N, 1–6 km, February–May) during the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign were calculated using a constrained photochemical box model. Estimates were made to assess the importance of local photochemical ozone production relative to transport in accounting for the springtime maximum in arctic free tropospheric ozone. Ozone production and loss rates from our diel steady-state box model constrained by median observations were first compared to two point box models, one run to instantaneous steady-state and the other run to diel steady-state. A consistent picture of local ozone photochemistry was derived by all three box models suggesting that differences between the approaches were not critical. Our model-derived ozone production rates increased by a factor of 28 in the 1–3 km layer and a factor of 7 in the 3–6 km layer between February and May. The arctic ozone budget required net import of ozone into the arctic free troposphere throughout the campaign; however, the transport term exceeded the photochemical production only in the lower free troposphere (1–3 km) between February and March. Gross ozone production rates were calculated to increase linearly with NOx mixing ratios up to ∼300 pptv in February and for NOx mixing ratio

Adverse Childhood Experiences in Rural and Urban Contexts

Recent research shows that rural children are more likely than urban children to experience certain kinds of adversity. Researchers at the Maine Rural Health Research Center looked at how adverse childhood experiences (ACEs) have affected rural and urban adults. Using data from the Behavioral Risk Factor Surveillance System Assessment, this study found that, while the prevalence of ACEs was comparable in rural and urban adults, over half of rural adults surveyed reported having ACE exposure.Among those with any ACE history, about one quarter experienced four or more ACEs. Policy implications and strategies are highlighted in this brief. Key Findings: Past research has shown that adverse childhood experiences (ACEs) have long-term, negative implications for health and well-being: as the number of ACEs increases, the risk for health problems in adulthood rises. Adverse childhood experiences (ACEs) are a significant problem among rural adults. Over half of rural residents reported some ACE exposure, and over one in ten reported high levels of exposure (four or more ACEs). After adjustment for demographics, rural and urban populations showed similar odds of experiencing high-level ACE exposure. Rural primary care providers can play a leadership role in forging community partnerships to raise public awareness about ACEs, conduct ACE-focused community needs assessments, and launch initiatives to create new services geared toward building resilience in families