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Robust Maximum Flow Network Interdiction Considering Uncertainties in Arc Capacity and Resource Consumption
No full textThis article discusses a robust network interdiction problem considering uncertainties in arc capacities and resource consumption. The problem involves two players: an adversary seeking to maximize the flow of a commodity through the network and an interdictor whose objective is to minimize this flow. The interdictor plays first and selects network arcs to interdict, subject to a resource constraint. The problem is formulated as a bilevel problem, and an upper bound single level mix-integer linear formulation is derived. The upper bound formulation is solved using three heuristics tailored for this problem and the network structure, based on Lagrangian relaxation and Benders’ decomposition. On average, each heuristic provides a reduction in run time of at least 85% compared to a state-of-the-art solver. Enhanced Benders’ decomposition achieves a solution with an optimality gap of less than 5% for all tested instances. Sensitivity analyses are conducted for the level of uncertainty in network parameters and the uncertainty budget. Robust decisions are also compared to decisions not accounting for uncertainty to evaluate the value of robustness, showing a reduction in simulation maximum flows by as much as 89.5%
Using Flipped Classroom Modules to Facilitate Higher Order Learning in Undergraduate Organic Chemistry
Get PDFIn an ongoing effort to incorporate active learning and promote higher order learning outcomes in undergraduate organic chemistry, a hybrid (“flipped”) classroom structure has been used to facilitate a series of collaborative activities in the first two courses of the lower division organic chemistry sequence. An observational study of seven classes over a five-year period reveals there is a strong correlation between performance on the in-class activities and performance on the final exam across all classes; however, a significant number of students in these courses continue to struggle on both the in-class activities and final exam. The Activity Engagement Survey (AcES) was administered in the most recent course offering included in this study, and these preliminary data suggest that students who achieved lower scores on the in-class activities had lower levels of emotional and behavioral/cognitive engagement and were less likely to work in collaborative groups. In total, these findings suggest that if students can be guided to engage more successfully with the in-class activities, they are likely to be more successful in carrying out the higher order learning required on the final exam. In addition to the analyses of student performance and engagement in the in-class activities, the implementation of the flipped classroom structure and suggestions for how student engagement in higher order learning might be improved in future iterations of the class are described herein
Exploring Environmental DNA as a Method for Monitoring Biological Characteristics of Surface Waters in the Tualatin River Watershed
No full textEnvironmental DNA (eDNA) refers to DNA shed by organisms into the environment, and can be captured in water, soil or air samples. By identifying DNA captured in a sample, we can infer species present within a given environment. As such, eDNA is a promising tool for understanding spatial and temporal variation in biodiversity across a watershed. Clean Water Services (CWS), a water resource and recovery district serving Washington County, Oregon, discharges to the Tualatin River, a meandering, valley-floor river, sensitive to nutrient inputs and stream flow augmentation. Accordingly, we use macroinvertebrates surveys to monitor the biological characteristics with the watershed as part of our water-shed based NPDES permit. However, macroinvertebrate surveys and the indices used to analyze them are not well suited for river systems like the Tualatin. This results in a lack of resolution of changes in predicted water quality year over year. Given these challenges, we are piloting eDNA as a novel method for gaining detailed biological information. Using a metabarcoding approach, this pilot monitored nine sites representing diverse habitats within the Tualatin River Watershed, on a monthly or quarterly basis. the goal of this phase, which was to understand spatial and temporal trends in biodiversity between sites, and determine the benefits and limitations of using eDNA metabarcoding analysis. This presentation will encompass preliminary results, ongoing studies, regional partnerships, and plans for the future use of eDNA at CWS
Soil Biogeochemical Changes in Response to Irrigation with Treated Wastewater
Get PDFElevated summer water temperatures in the Tualatin River are a major concern for salmonids and other temperature-sensitive species. One significant heat source is the input effluent from wastewater treatment plants. Clean Water Services, a water utility in Washington County, aims to reduce the amount of heat entering the river by recycling treated wastewater to irrigate restored wetlands near their Wastewater Resource Recovery Facilities. In addition to lessening the amount of heat discharged into receiving waters, irrigation with recycled water could provide ecosystem benefits, such as carbon (C) sequestration, increased biodiversity, and improved habitat quality. On the other hand, recycled water irrigation could have detrimental effects such as increased emissions of greenhouse gases [GHG; carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4)]. In this study, we measured aspects of soil C and nitrogen (N) cycling including soil GHG emissions. My hypothesis is that the wet conditions and elevated N caused by irrigation will increase N2O emissions but will not become anoxic enough to produce CH4.
The 26-acre project site is irrigated with recycled wastewater at agronomic rates throughout the dry summer months. In 2022 and 2023, we installed four replicate soil chambers in Irrigated and Control areas in three different soil types. Every two weeks, we collected gas samples to estimate fluxes of CO2, N2O and CH4. Preliminary results indicate no significant differences in GHG emissions between control and irrigated sites, likely owing to low rates of irrigation to avoid surface ponding
Primary Care as a Protective Factor: A Vision to Transform Health Care Delivery and Overcome Disparities in Health
Get PDFA large body of research demonstrates that experiences of trauma, especially when they occur in the absence of safe, stable, nurturing relationships (SSNRs) and environments— known as protective factors— interrupt healthy development and predispose both children and adults to the most common causes of physical and mental illness and early death.1,2 Because minoritized and low-income populations are exposed to more trauma and have access to fewer protective factors, they experience higher rates of trauma-related health and social problems and severe disparities in health.1–4 Primary care clinicians increasingly recognize the role that trauma plays in the health and well-being of their patients. Many nonetheless feel they lack the knowledge, skills, resources, and time to effectively address the causes and consequences of trauma. There also is little recognition that primary care, itself, can be a protective factor
Oregon State Ranking Assessment for Lewis\u27s Woodpecker (Melanerpes lewis)
Get PDFOregon State Ranking Assessment for Lewis\u27s woodpecker (Melanerpes lewis) by the Oregon Biodiversity Information Center, following NatureServe 2024 methodology
Influence of Curb Return and Crosswalk Setback on Turning Driver Decision-Making and Speed Selection
No full textThe location of curb ramps, crosswalk markings, and curb radius are important contributors to pedestrian safety at intersections, particularly for conflicts and crashes involving right turns. Drivers tend to have higher turning speeds at locations with larger curb radii, which also requires greater stopping sight distance. If the crosswalk is placed further away from the intersection corner (i.e., offset or setback from the intersection corner), it could potentially provide drivers better visibility of pedestrians and increase the available stopping distance. However, no study has previously been conducted to investigate the relationship between crosswalk location and curb radius. This paper presents the results of research that quantifies the relationship between the offset of crosswalks (setback crosswalk) and indirect safety measures (driver stopping, yielding, and speed selection) at intersections with the consideration of other characteristics during simulated driving. The study included field-based observations and driving simulator experiments. A driving simulator experiment with 50 participants was conducted to determine how setback distances, sharpness of curb radii, and presence of pedestrians affect driver stopping decision and position, and speed choice. Approximately 12 h of video (7:00 a.m.–7:00 p.m.) were collected at nine study sites that closely matched the designs tested in the driving simulator. Comparisons of drivers’ speed in a similar scenario obtained from field and simulator data were performed to benchmark the observations from the driving simulator against field data. Stop line speeds were found to be consistent between experiments and turning speeds were found to be slightly higher in the driving simulator experiment. The research results suggest that curb radius should be smaller [less than 9 m (30 ft)] to control driver speed. Additionally, a setback distance of 6 m (20 ft) is a suitable upper bound for crosswalk placement when reconstructing intersections
Two Neotropical Snakes Attacked As Prey by Army Ants in Costa Rica
No full textGeophis hoffmanni and Ninia sebae belong to a group of snake species informally referred to as “goo-eaters” due to their diet consisting entirely of soft-bodied invertebrates. Geophis hoffmanni is a nocturnal, terrestrial, and fossorial snake often found in herbaceous vegetation and leaf litter near humid areas. Ninia sebae is both terrestrial and fossorial, and is commonly found under logs, boards, leaf piles, and various types of cover objects. One of the most formidable predators in many tropical forests are army ants, which forage in “raids” involving large numbers of ants searching for food simultaneously in confined areas. The most prevalent species is Eciton burchelli, widely distributed across the Neotropics. In Costa Rica, Labidus spininodis is also common, primarily inhabiting wet forest areas. On January 2, 2022, we observed a colony of Eciton burchellii attacking a Geophis hoffmanni individual at Selva Verde Lodge. The ants killed the snake, but we couldn\u27t observe what happened afterward. On September 23, 2022, we encountered a swarm of Labidus spininodis ants attacking a Ninia sebae individual at Soltis Center. We couldn\u27t determine whether the ants killed the snake, but it remained motionless after approximately 40 minutes of ant attacks, and some ant workers were seen cutting pieces from the snake\u27s body. Both incidents occurred in the northern lowlands of the Caribbean slope of Costa Rica. These are two unprecedented cases of predation on Neotropical dipsadid snakes by two species of army ants. These instances mark the first reported cases of these emblematic terrestrial predators capturing relatively large vertebrates. Geophis hoffmanni y Ninia sebae pertenecen al grupo de serpientes “comedoras de gusanos” pues su dieta consiste exclusivamente en invertebrados de cuerpo blando. Geophis hoffmanni es nocturna, terrestre, fosorial y se encuentra frecuentemente en la vegetación herbácea y la hojarasca de áreas húmedas. Ninia sebae es terrestre, fosorial y se encuentra comúnmente debajo de troncos, montones de hojas y tablas entre otros. Uno de los depredadores más formidables en bosques tropicales son las hormigas guerreras, que se alimentan en grandes grupos en áreas confinadas. Eciton burchelli está ampliamente distribuida en toda la región neotropical. En Costa Rica, Labidus spininodis también es común y habita principalmente áreas de bosque húmedo. El 2 de enero de 2022, observamos una colonia de Eciton burchellii atacando y matando a una Geophis hoffmanni en Selva Verde Lodge, aunque no pudimos observar qué sucedió después. El 23 de septiembre de 2022, encontramos un grupo de Labidus spininodis atacando a una Ninia sebae en el Centro Soltis. No pudimos determinar si las hormigas mataron a la serpiente, pero esta permaneció inmóvil después de aproximadamente 40 minutos de ataques de las hormigas, e incluso se observó a algunas obreras cortando trozos del cuerpo de la serpiente. Los dos sitios mencionados se ubican en las tierras bajas de la vertiente norte de Costa Rica. Estos son dos casos sin precedentes de depredación de serpientes dipsádidas neotropicales por dos especies de hormigas guerreras. Estas instancias marcan los primeros casos documentados de estos emblemáticos depredadores terrestres capturando vertebrados relativamente grandes
Video As Text: A New Paradigm for Flexible Video Analysis
No full textThe ability to capture and distribute digital videos has been available for many years. Users can easily capture high-quality video streams with mobile devices and distribute them to end users through varying platforms. This paper presents the design and implementation of a new multimedia framework called Video as Text (vText), which analyzes and manipulates video data as trivially as we handle text data in most Unix and Linux systems. In most Unix systems, it is easy to accomplish highly complex textual analysis and processing by combining relatively simple programs (e.g., grep, awk, sed, and cut) through Unix pipes. The vText paradigm seeks to mimic such programs. We demonstrate the design and implementation of vText linking video codecs with computer vision and image-processing algorithms. The experimental results indicate that the combination of simple programs provides high flexibility to users but does not incur high overhead when processing the video data
Intersections between Science and Social Justice: A Conversation with Liza Finkel
Get PDFIn preparation for the special issue: Cascading Crises: Power, Equity and Liberation, the Editors of NWJTE sat down for a conversation with Dr. Liza Finkel, a Science Teacher Educator in the Graduate School of Education and Counseling at Lewis & Clark College. Dr. Finkel’s passions include science (especially geology), finding intersections between science and social justice and helping new teachers learn to include those connections in their teaching, knitting, cooking, birding, and reading mystery novels with women protagonists