Digital Commons Network^™

Efficient Algorithms For Identifying Loop Formation And Computing Θ Value For Solving Minimum Cost Flow Network Problems, Timothy Michael Chávez, Duc Thai Nguyen

Computational Modeling & Simulation Engineering Faculty Publications

While the minimum cost flow (MCF) problems have been well documented in many publications, due to its broad applications, little or no effort have been devoted to explaining the algorithms for identifying loop formation and computing the value needed to solve MCF network problems. This paper proposes efficient algorithms, and MATLAB computer implementation, for solving MCF problems. Several academic and real-life network problems have been solved to validate the proposed algorithms; the numerical results obtained by the developed MCF code have been compared and matched with the built-in MATLAB function Linprog() (Simplex algorithm) for further validation.

Laypeople Perception And Interpretation Of Simulated Life-Threatening Bleeding: A Controlled Experimental Study, Erik Prytz, Rachel Phillips, Susanna Lönnqvist, Marc Friberg, Carl-Oscar Jonson

Psychology Faculty Publications

Introduction

First aid performed by immediate responders can be the difference between life and death in the case of trauma with massive bleeding. To develop effective training programs to teach bleeding control to laypersons, it is important to be aware of beliefs and misconceptions people hold on bleeding and severity of bleeding situations.

Method

A controlled study was conducted in which 175 American college students viewed 78 video clips of simulated bleeding injuries. The volume of blood present (between 0 and 1900 ml), rate of blood flow, and victim gender were systematically varied within participants. Participants were asked to rate …

Part 3: Earn While You Learn: The Apprentice School At Newport News Shipbuilding, Dragas Center For Economic Analysis And Policy

State of the Region Reports: Hampton Roads

The Apprentice School at Newport News Shipbuilding is not only one of the nation’s premier schools for educating and training workers, but it also stands as an example of how 21st-century learning can occur in the region. In this chapter, we look at the apprenticeship model and delve into the unique aspects of The Apprentice School that have made it successful.

Part 5: Whither Old Dominion University?, Dragas Center For Economic Analysis And Policy

State of the Region Reports: Hampton Roads

The University of Virginia, Virginia Tech and College of William & Mary historically have played important roles in the Commonwealth. They have set impressive records in admitting and graduating talented students who (predictably) do well after they leave these campuses. Nevertheless, the future viability and cohesion of the Commonwealth in this century will more likely be determined on campuses like Old Dominion University, for it is there that the critical social mobility challenge is being addressed in a meaningful way. We explore what the future may hold for ODU.

Odu Professors Study Gulf Stream Decline, News @ Odu

News Items

No abstract provided.

Thank You To Our 2020 Peer Reviewers, Susan Trumbore, Ana P. Barros, Thorsten W. Becker, Eric A. Davidson, Bethany L. Ehlmann, Nicolas Gruber, Eileen Hofmann, Mary K. Hudson, Tissa H. Illangasekare, Sarah Kang, Paola Malanotte-Rizzoli, Alberto Montanari, Francis Nimmo, Tom Parsons, Vincent J.M. Salters, David Schimel, Bjorn Stevens, Donald Wuebbles, Peter Zeitler, Tong Zhu

CCPO Publications

No abstract provided.

Impacts Of Multiple Environmental Changes On Long‐Term Nitrogen Loading From The Chesapeake Bay Watershed, Shufen Pan, Zihao Bian, Hanqin Tian, Yuanzhi Yao, Raymond G. Najjar, Marjorie A.M. Friedrichs, Eileen E. Hofmann, Rongting Xu, Bowen Zhang

CCPO Publications

Excessive nutrient inputs from land, particularly nitrogen (N), have been found to increase the occurrence of hypoxia and harmful algal blooms in coastal ecosystems. To identify the main contributors of increased N loading and evaluate the efficacy of water pollution control policies, it is essential to quantify and attribute the long‐term changes in riverine N export. Here, we use a state‐of‐the‐art terrestrial–aquatic interface model to examine how multiple environmental factors may have affected N export from the Chesapeake Bay watershed since 1900. These factors include changes in climate, carbon dioxide, land use, and N inputs (i.e., atmospheric N deposition, animal …

Dynamical Downscaling Projections Of Late 21st Century U.S. Landfalling Hurricane Activity, Thomas R. Knutson, Joseph J. Sirutis, Morris A. Bender, Robert E. Tuleya

CCPO Publications

U.S. landfalling tropical cyclone (TC) activity was projected for late 21st century conditions using a two-step dynamical downscaling framework. A regional atmospheric model, run for 27 seasons, generated tropical storm cases. Each storm case was re-simulated (up to 15 days) using the higher resolution GFDL hurricane model. Thirteen CMIP3 or CMIP5 modeled climate change projections were explored as scenarios. Robustness of projections was assessed using statistical significance tests and comparing the sign of changes derived from different models. The proportion of TCs (tropical storms and hurricanes) making U.S. landfall increases for the warming scenarios (by order 50% or more). For …

Riverine Carbon Cycling Over The Past Century In The Mid‐Atlantic Region Of The United States, Yuanzi Yao, Hanqin Tian, Shufen Pan, Raymond G. Najjar, Marjorie A.M. Friedrichs, Zihao Bian, Hong-Yi Li, Eileen E. Hofmann

CCPO Publications

The lateral transport and degassing of carbon in riverine ecosystems is difficult to quantify on large spatial and long temporal scales due to the relatively poor representation of carbon processes in many models. Here, we coupled a scale‐adaptive hydrological model with the Dynamic Land Ecosystem Model to simulate key riverine carbon processes across the Chesapeake and Delaware Bay Watersheds from 1900 to 2015. Our results suggest that throughout this time period riverine CO₂ degassing and lateral dissolved inorganic carbon fluxes to the coastal ocean contribute nearly equally to the total riverine carbon outputs (mean ± standard deviation: 886 ± …

Developing An Institutional Arrangement For A Whole-Of-Government And Whole-Of-Community Approach To Regional Adaptation To Sea Level Rise: The Hampton Roads Pilot Project, Juita-Elena (Wie) Yusuf, J. Gail Nicula, Burton St. John Iii, Meagan M. Jordan, Michelle Covi, Carol Considine, Marina Saitgalina, Joshua Behr

School of Public Service Faculty Publications

Adaptation to sea level rise (SLR) requires coordination among local, state, and federal entities and collaboration across governments, nonprofits, businesses, and residents. This coordination and collaboration are reflected in institutional arrangements associated with a whole-of-government and whole-of-community approach to regional adaptation. This study analyzes the development of an interlocal agreement (ILA), the Hampton Roads Sea Level Rise Preparedness and Resilience Intergovernmental Planning Pilot Project (the Pilot Project), as an example of such an arrangement. This study assesses how factors throughout three phases of ILA development (initiation, implementation, and execution) influence outcomes and effectiveness. Drawing upon participant observation, document analysis, survey …

Computational Decision Support For The Covid-19 Healthcare Coalition, Andreas Tolk, Christopher Glazner, Joseph Ungerleider

VMASC Publications

In the early months of 2020, the SARS-CoV-2 Coronavirus took the world by surprise, resulting in the COVID-19 pandemic that has caused significant loss of lives and challenged the sustainability of our health care systems. In mid-March, it became obvious that government and communities had to react immediately. Under the lead of the Mayo Clinic and The MITRE Corporation, the COVID-19 Healthcare Coalition (C19HCC) was established as a coordinated public-interest, private-sector response. The coalition brought healthcare organizations, technology firms, nonprofits, academia, and startups to support supply chains, inform coordinated social policies, and provide data-driven insights to protect people and preserve …

Exploring The Relationship Between Clout And Cognitive Processing In Mooc Discussion Forums, Robert L. Moore, Cherng-Jyh Yen, F. Eamonn Powers

STEMPS Faculty Publications

The purpose of this study was to explore the relationship between clout and cognitive processing in massive open online course (MOOC) discussion forum posts. Cognitive processing, a category variable generated by the automated text analysis tool, Linguistic Inquiry Word Count (LIWC), is made up of six sub-scores (insight, causation, discrepancy, tentativeness, certainty and differentiation). Clout is a nontransparent summary variable in LIWC that can be used to understand the level of confidence conveyed in the text. Because clout is nontransparent, we do not know the algorithm used to calculate its value. To better understand this variable, this study examined cognitive …

Safety Training For Career And Content Switchers, Philip A. Reed, M. Kathleen Ferguson

STEMPS Faculty Publications

No abstract provided.

Assessing An Academic Readiness Model In A Community College Occupational Program, Scott A. Hauert, Robert L. Moore, Quinton Nottingham

STEMPS Faculty Publications

This study assessed a localized academic readiness model that measures academic skills relevant to an occupational program and the institutional context. Enrollment in the program’s mandatory gateway course is contingent upon establishing academic readiness either: (1) possess an associate-level or higher degree; (2) achieve placement test scores that permit enrollment in college-level English composition/critical reading; or (3) complete developmental education prerequisites to permit enrollment in college-level English composition/critical reading. Using the gateway course performance for 112 students, the study explored whether any of the model’s criterions are significantly related to success in the gateway course and whether there is any …

When Failure Is An Option: A Scoping Review Of Failure States In Game-Based Learning, F. Eamonn Powers, Robert L. Moore

STEMPS Faculty Publications

As interest in the use of games and gaming elements within learning environments grows, educators and designers may find it easier to account for winning than for losing and failure. This scoping review examines the role of failure and loss within game-based instructional interventions. Because of the varied methods and relatively small number of articles directly addressing the intersection between failure and loss within game-based instructional interventions, a scoping review was undertaken. This review included 14 peer-reviewed articles which explored a range of instructional contexts implementing failure state game mechanics. We identify several key takeaways that indicate how failure state …

Lights, Camera, Activity! A Systematic Review Of Research On Learner-Generated Videos, Bridgette Shade Epps, Tian Luo, Pauline S. Muljana

STEMPS Faculty Publications

Aim/Purpose

The current literature discusses the use and benefits of learner-generated videos (LGVs). However, it rarely addresses any correlation between the types of subjects that are best suited for using these videos or what techniques should accompany the use of LGVs.

Background

This systematic review synthesizes current literature to identify patterns and implications that develop from the use of LGVs so that their future use can be both consistent and effective. This paper also reviews the studies to establish the most consistent educational benefits that emerge from this activity.

Methodology

Employing the Preferred-Reporting of Items for Systematic Reviews and Meta-Analyses …

Comparative Review On Information And Communication Technology Issues In Education Sector Of Developed And Developing Countries: A Case Study About Pakistan, Aasma Akram, Moshin Nazir, Tayyaba Batool, Muhammad Imran Zulfiqar, Maria Nazir, Habiba Azhar, Sadia Murawwat

STEMPS Faculty Publications

The use of information and communication technology is very beneficial in the education sector because it can enhance the quality of education. However, the implementation of ICT in the education sector of developed and developing countries is a challenging task. This paper explains the comparative study of ICT issues in the education sector of developed and developing countries. In particular, we compare issues between Pakistan and high-tech countries. Our study reveals the fact that the education sector is facing numerous ICT problems that are based on culture, finance, management, infrastructure, lack of training, lack of equipment, teacher’s refusal, and ethical …

The Role Of Stereotype Threat In Ethnically Minoritized Students' Science Motivation: A Four-Year Longitudinal Study Of Achievement And Persistence In Stem, Delaram A. Totonchi, Tony Perez, You-Kyung Lee, Kristy A. Robinson, Lisa Linnenbrink-Garcia

STEMPS Faculty Publications

Grounded in expectancy-value and stereotype threat theories, this four-year longitudinal study examined associations between changes in stereotype threat and motivation (self-efficacy, task values, and perceived costs) among 425 undergraduates from racial/ethnic groups typically underrepresented in science, technology, engineering, and mathematics (STEM). Growth analyses indicated that students' stereotype threat and perceived cost of studying science increased during college, whereas science self-efficacy, intrinsic value, and attainment value declined. Parallel growth analyses suggested that higher initial stereotype threat related to a faster decline in attainment value and faster increase in perceived costs throughout college. Higher initial levels and a steeper increase in stereotype …

Introduction To The Special Section On Designing For Learning In A Pandemic, John Baaki

STEMPS Faculty Publications

Amid the pandemic, a project team continued educating electrical line workers across four U.S. locations. The Center for Engineering Education and Outreach redesigned an in-person internship program by finding ways to simulate tinkering, design reviews, and troubleshooting activities. A collaborative four-day international seminar networking 10 European universities from eight different countries went virtual. An all-expenses-paid six-day residential summer experience at NASA’s Johnson Space Center was replaced by an online experience. Designers embraced—cancellation is not an option—and found a way to engage fifth grade students to apply science and mathematics concepts related to building a Mars colony. The show did go …

Part 5: Viewed Through A Different Lens: Evaluating Virginia Higher Education, Dragas Center For Economic Analysis And Policy, Old Dominion University

State of the Commonwealth Reports

The University of Virginia, Virginia Tech and William & Mary historically have played important roles in the Commonwealth. They have assembled impressive records in admitting and graduating talented students who (predictably) do well after they leave these campuses. Except for our historically black colleges and universities (HBCUs) and the University of Virginia’s College at Wise, no public four-year institution in Virginia enrolls a significant percentage of low-income students. We discuss what the Commonwealth and its public colleges and universities can do to make higher education more affordable.

High Voltage Design And Evaluation Of Wien Filters For The Cebaf 200 Kev Injector Upgrade, Gabriel Palacios-Serrano, Helmut Baumgart, C. Hernández-García, P. Adderley, J. Benesch, D. Bullard, J. Grames, A. Hofler, D. Machie, M. Poelker, M. Stutzman, R. Suleiman

Electrical & Computer Engineering Faculty Publications

High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. …

Central Equatorial Pacific Cooling During The Last Glacial Maximum, Minda Moriah Monteagudo, Jean Lynch-Stieglitz, Thomas M. Marchitto, Matthew W. Schmidt

OES Faculty Publications

Establishing tropical sea surface temperature (SST) during the Last Glacial Maximum (LGM) is important for constraining equilibrium climate sensitivity to radiative forcing. Until now, there has been little data from the central equatorial Pacific in global compilations, with foraminiferal assemblage‐based estimates suggesting the region was within 1°C of modern temperatures during the LGM. This is in stark contrast to multi‐proxy evidence from the eastern and western Pacific and model simulations which support larger cooling. Here we present the first estimates of glacial SST in the central equatorial Pacific from Mg/Ca in Globigerinoides ruber. Our results show that the central Pacific …

Adenosine Triphosphate (Atp) As A Metric Of Microbial Biomass In Aquatic Systems: New Simplified Protocols, Laboratory Validation, And A Reflection On Data From The Literature, Alexander B. Bochdansky, Alison N. Stouffer, Nyjaee N. Washington

OES Faculty Publications

The use of adenosine triphosphate (ATP) as a universal biomass indicator is built on the premise that ATP concentration tracks biomass rather than the physiological condition of cells. However, reportedly high variability in ATP in response to environmental conditions is the main reason the method has not found widespread application. To test possible sources of this variability, we used the diatom Thalassiosira weissflogii as a model and manipulated its growth rate through nutrient limitation and through exposure to three different temperatures (15°C, 20°C, and 25°C). We simplified the ATP protocol with hot‐water or chemical extraction methods, modified a commercially available …

Salt Marsh Hydrogeology: A Review, Julia Guimond, Joseph Tamborski

OES Faculty Publications

Groundwater–surface water exchange in salt marsh ecosystems mediates nearshore salt, nutrient, and carbon budgets with implications for biological productivity and global climate. Despite their importance, a synthesis of salt marsh groundwater studies is lacking. In this review, we summarize drivers mediating salt marsh hydrogeology, review field and modeling techniques, and discuss patterns of exchange. New data from a Delaware seepage meter study are reported which highlight small-scale spatial variability in exchange rates. A synthesis of the salt marsh hydrogeology literature reveals a positive relationship between tidal range and submarine groundwater discharge but not porewater exchange, highlighting the multidimensional drivers of …

A Coastal N₂ Fixation Hotspot At The Cape Hatteras Front: Elucidating Spatial Heterogeneity In Diazotroph Activity Via Supervised Machine Learning, Corday R. Selden, P. Dreux Chappell, Sophie Clayton, Alfonso Macías-Tapia, Peter W. Bernhardt, Margaret R. Mulholland

OES Faculty Publications

In the North Atlantic Ocean, dinitrogen (N₂) fixation on the western continental shelf represents a significant fraction of basin‐wide nitrogen (N) inputs. However, the factors regulating coastal N₂ fixation remain poorly understood, in part due to sharp physico‐chemical gradients and dynamic water mass interactions that are difficult to constrain via traditional oceanographic approaches. This study sought to characterize the spatial heterogeneity of N₂ fixation on the western North Atlantic shelf, at the confluence of Mid‐ and South Atlantic Bight shelf waters and the Gulf Stream, in August 2016. Rates were quantified using the ¹⁵N_{2 …}

Toward Resolving Disparate Accounts Of The Extent And Magnitude Of Nitrogen Fixation In The Eastern Tropical South Pacific Oxygen Deficient Zone, Corday R. Selden, Margaret R. Mulholland, Brittany Widner, Peter Bernhardt, Amal Jayakumar

OES Faculty Publications

Examination of dinitrogen (N₂) fixation in the Eastern Tropical South Pacific oxygen deficient zone has raised questions about the range of diazotrophs in the deep sea and their quantitative importance as a source of new nitrogen globally. However, technical considerations in the deployment of stable isotopes in quantifying N₂ fixation rates have complicated interpretation of this research. Here, we report the findings of a comprehensive survey of N₂ fixation within, above and below the Eastern Tropical South Pacific oxygen deficient zone. N₂ fixation rates were measured using a robust ¹⁵N tracer method (bubble removal) …

Pore Water Exchange-Driven Inorganic Carbon Export From Intertidal Salt Marshes, Joeseph J. Tamborski, Meagan Eagle, Barret L. Kurylyk, Kevin D. Kroeger, Zhaoihui Aleck Wang, Paul Henderson, Matthew A. Charette

OES Faculty Publications

Respiration in intertidal salt marshes generates dissolved inorganic carbon (DIC) that is exported to the coastal ocean by tidal exchange with the marsh platform. Understanding the link between physical drivers of water exchange and chemical flux is a key to constraining coastal wetland contributions to regional carbon budgets. The spatial and temporal (seasonal, annual) variability of marsh pore water exchange and DIC export was assessed from a microtidal salt marsh (Sage Lot Pond, Massachusetts). Spatial variability was constrained from ²²⁴Ra : ²²⁸Th disequilibria across two hydrologic units within the marsh sediments. Disequilibrium between the more soluble ²²⁴Ra …

Larry Philip Atkinson 1941-2020, Gregory Cutter, Louis Codispoti

OES Faculty Publications

No abstract provided.

The Renaissance Of Odum's Outwelling Hypothesis In 'Blue Carbon' Science, Isaac R. Santos, David J. Burdige, Tim C. Jennerjahn, Steven Bouillon, Alex Cabral, Oscar Serrano, Thomas Wernberg, Karen Filbee-Dexter, Julia A. Guimond, Joseph J. Tamborski

OES Faculty Publications

The term ‘Blue Carbon’ was coined about a decade ago to highlight the important carbon sequestration capacity of coastal vegetated ecosystems. The term has paved the way for the development of programs and policies that preserve and restore these threatened coastal ecosystems for climate change mitigation. Blue carbon research has focused on quantifying carbon stocks and burial rates in sediments or accumulating as biomass. This focus on habitat-bound carbon led us to losing sight of the mobile blue carbon fraction. Oceans, the largest active reservoir of carbon, have become somewhat of a blind spot. Multiple recent investigations have revealed high …

Trichome Lengths Of The Heterocystous N2-Fixing Cyanobacteria In The Tropical Marginal Seas Of The Western North Pacific, Sing-How Tuo, Margaret R. Mulholland, Yukiko Taniuchi, Houng-Yung Chen, Wann-Neng Jane, Yen-Huei Lin, Yuh-Ling Lee Chen

OES Faculty Publications

Calothrix rhizosoleniae and Richelia intracellularis are heterocystous cyanobacteria found in the tropical oceans. C. rhizosoleniae commonly live epiphytically on diatom genera Chaetoceros (C-C) and Bacteriastrum (B-C) while R. intracellularis live endosymbiotically within Rhizosolenia (R-R), Guinardia (G-R), and Hemiaulus (H-R); although, they occasionally live freely (FL-C and FL-R). Both species have much shorter trichomes than the other marine filamentous cyanobacteria such as Trichodesmium spp. and Anabaena gerdii. We investigated the trichome lengths of C. rhizosoleniae and R. intracellularis in the South China Sea (SCS) and the Philippine …