Digital Commons Network^™

The Effects Of Climate Change On Biodiversity: Pressing Issues And Research Priorities, Friedhelm Krupp, Lytton J. Musselman, Mohammed M.A. Kotb, Ilka Weidig

Biological Sciences Faculty Publications

No abstract provided.

Embedding Simulation Education Into The Engineering Management Body Of Knowledge, Andreas Tolk, Ghaith Rabadi, Donald N. Merino

Computational Modeling & Simulation Engineering Faculty Publications

The American Society for Engineering Management (ASEM) established a Body of Knowledge (BoK). As simulation is of growing interest to engineers in general and to engineering managers in particular, simulation is part of this documentation of domains of interest that characterise the profession. The basis for the Body of Knowledge comprises of established and accredited curricula and additional input from practitioners of the field. As it is essential to cover the basic topics and core competences as well as application specific domain knowledge, the simulation education for engineers is categorised into topics on simulation theory and simulation application.

Photochemical Degradation Of Dissolved Organic Matter And Dissolved Lignin Phenols From The Congo River, Robert G. M. Spencer, Aron Stubbins, Peter J. Hernes, Kenneth Mopper, Anthony K. Aufdenkampe, Rachael Y. Dyda, Vincent L. Mwamba, Arthur M. Mangangu, Jose N. Wabakanghanzi, Johan Six

Chemistry & Biochemistry Faculty Publications

Photochemical degradation of Congo River dissolved organic matter (DOM) was investigated to examine the fate of terrigenous DOM derived from tropical ecosystems. Tropical riverine DOM receives greater exposure to solar radiation, particularly in large river plumes discharging directly into the open ocean. Initial Congo River DOM exhibited dissolved organic carbon (DOC) concentration and compositional characteristics typical of organic rich blackwater systems. During a 57 day irradiation experiment, Congo River DOM was shown to be highly photoreactive with a decrease in DOC, chromophoric DOM (CDOM), lignin phenol concentrations (Σ8) and carbon-normalized yields (Λ8), equivalent to losses of ~45, 85–95, >95 and …

A Two-Population Insurgency In Colombia: Quasi-Predator-Prey Models - A Trend Towards Simplicity, John A. Adam, John A. Sokolowski, Catherine M. Banks

Mathematics & Statistics Faculty Publications

A sequence of analytic mathematical models has been developed in the context of the "low-level insurgency" in Colombia, from 1993 to the present. They are based on generalizations of the two-population "predator-prey" model commonly applied in ecological modeling, and interestingly, the less sophisticated models yield more insight into the problem than the more complicated ones, but the formalism is available to adapt the model "upwards" in the event that more data becomes available, or as the situation increases in complexity. Specifically, so-called "forcing terms" were included initially in the coupled differential equations to represent the effects of government policies towards …

Volume Viscosity In Fluids With Multiple Dissipative Processes, Allan J. Zuckerwar, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

The variational principle of Hamilton is applied to derive the volume viscosity coefficients of a reacting fluid with multiple dissipative processes. The procedure, as in the case of a single dissipative process, yields two dissipative terms in the Navier-Stokes equation: The first is the traditional volume viscosity term, proportional to the dilatational component of the velocity; the second term is proportional to the material time derivative of the pressure gradient. Each dissipative process is assumed to be independent of the others. In a fluid comprising a single constituent with multiple relaxation processes, the relaxation times of the multiple processes are …

Pressure-Driven Transport Of Particles Through A Converging-Diverging Microchannel, Ye Ai, Sang W. Joo, Xiangchun Xuan, Shizhi Qian

Mechanical & Aerospace Engineering Faculty Publications

Pressure-driven transport of particles through a symmetric converging-diverging microchannel is studied by solving a coupled nonlinear system, which is composed of the Navier-Stokes and continuity equations using the arbitrary Lagrangian-Eulerian finite-element technique. The predicted particle translation is in good agreement with existing experimental observations. The effects of pressure gradient, particle size, channel geometry, and a particle's initial location on the particle transport are investigated. The pressure gradient has no effect on the ratio of the translational velocity of particles through a converging-diverging channel to that in the upstream straight channel. Particles are generally accelerated in the converging region and then …

Biomedical Technology: Supporting Movement, Petros Katsioloudis

STEMPS Faculty Publications

According to the National Institute on Disability and Rehabilitation Research, an estimated 8.5 million children 21 years and younger have a disability (Jans & Stoddard, 1999). After about a decade, with the development of new and sophisticated materials (aluminum alloys, titanium alloys, and carbon fibers) and the integration of electronics, it was then possible to significantly improve the performance of prostheses, built with the so-called endo skeletal (or skeletal-modular) method (Mora, Beratni & Pedrotti, 2006).

Review Of The Chaco Experience: Landscape And Ideology At The Center Place, By Ruth Van Dyke, Bennett Huffman

Reconstruction: Studies in Contemporary Culture

[First paragraph]

Sometimes one enters a book with preconceived ideas that get in the way of a complete appreciation of its contents. Such was this reviewer's experience with Ruth Van Dyke's treatment of the meaning of Anasazi architecture at what many consider the capital of that culture in and around the great sites of Chaco Canyon, New Mexico. One aspect that contributed to this conflict between this reviewer's ideas and that presented by the book is the subtitle of the book: "Landscape and Ideology at the Center Place." Center Place can mean political and cultural center, which presents no problems …

Surface Deformation Induced By Present-Day Ice Melting In Svalbard, H. P. Kierulf, H.-P. Plag, J. Kohler

CCPO Publications

The vertical movement of the Earth's surface is the result of a number of internal processes in the solid Earth, tidal forces and mass redistribution in the atmosphere, oceans, terrestrial hydrosphere and cryosphere. Close to ice sheets and glaciers, the changes in the ice loads can induce large vertical motions at intraseasonal to secular timescales. The Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI) antennas in Ny-Ålesund, Svalbard that started observations in 1991 and 1995, respectively, observe vertical uplift rates on the order of mm yr−1, which are considerably larger than those predicted by postglacial rebound (PGR) models …

High-Performance Broadcast And Multicast Protocols For Multi-Radio Multi-Channel Wireless Mesh Networks, Jun Wang

Electrical & Computer Engineering Theses & Dissertations

Recently, wireless mesh networks (WMNs) have attracted much attention. A vast amount of unicast, multicast and broadcast protocols has been developed for WMNs or mobile ad hoc networks (MANETs). First of all, broadcast and multicast in wireless networks are fundamentally different from the way in which wired networks function due to the well-known wireless broadcast/multicast advantage. Moreover, most broadcast and multicast protocols in wireless networks assume a single-radio single-channel and single-rate network model, or a generalized physical model, which does not take into account the impact of interference. This dissertation focuses on high-performance broadcast and multicast protocols designed for multi-radio …

Sensitive Detection Of Novel Effects And Characteristic Signal Structure Of Higher Harmonic Detection In Wavelength Modulation Spectroscopy, Mohammad Amir Khan

Electrical & Computer Engineering Theses & Dissertations

We discuss experimental and theoretical results of absorption features of the oxygen A-band transitions when synchronous detection at higher harmonics using Wavelength Modulation Spectroscopy (WMS) is performed. A key aspect of structure higher harmonic detection is discussed. It is shown that the signal magnitude and spectral locations of turning points and zero crossings of WMS signal demonstrate key signatures of collision dynamics of gaseous specie parameters and lineshape parameters. In addition, it is also shown that these salient features provide sensitive probes for any changes in the gas environment or lineshape parameters. We discuss several advantages and subtle physical effects …

Comparative Study Of Forward And Diffusely Scattered Light In A Coherently Prepared Ultracold Rubidium Gas, Rocio Gisel Olave Gonzalez

Physics Theses & Dissertations

A comparison between forward and diffusely scattered light propagating in a coherently prepared ultracold ⁸⁷Rb atomic vapor is presented. This research is part of the ongoing effort to characterize the processes, such as diffusion, that contribute to coherence loss in atomic media under conditions of electromagnetically induced transparency, for applications in realistic systems. Toward this end, a magneto optical trap (MOT) of ⁸⁷Rb has been built, and the atomic vapor sample characterized in terms of atomic density, shape and size, temperature, and optical depth. Next, two co-propagating beams were sent through the sample, to establish an electromagnetically induced …

Management And Social Indicators Of Soil Carbon Storage In A Residential Ecosystem, Midlothian, Va, Christopher M. Gough, Eliza A. Fritz

Virginia Journal of Science

Soil carbon storage- defined here as carbon mass per unit ground area- is an important ecosystem service, sequestering carbon that might otherwise exist in atmospheric CO₂ . Significant attention has focused on the effects that humans have on carbon cycling, but little is known about how human behaviors and attitudes relate to lawn carbon storage. The objectives of this study were to conduct household surveys in concert with soil carbon sampling in a 10-year-old exurban neighborhood near Richmond, Virginia to quantify differences in soil carbon storage between residential lawns and mixed pine-hardwood forest fragments, and to determine how lawn …

Gas-Kinetic Schemes For Direct Numerical Simulations Of Compressible Homogeneous Turbulence, Wei Liao, Yan Peng, Li-Shi Luo

Mathematics & Statistics Faculty Publications

We apply the gas-kinetic scheme (GKS) for the direct numerical simulations (DNSs) of compressible decaying homogeneous isotropic turbulence (DHIT). We intend to study the accuracy, stability, and efficiency of the gas-kinetic scheme for DNS of compressible homogeneous turbulence depending on both flow conditions and numerics. In particular, we study the GKS with multidimensional, quasi-one-dimensional, dimensional-splitting, and smooth-flow approximations. We simulate the compressible DHIT with the Taylor microscale Reynolds number Reλ =72.0 and the turbulence Mach number Ma_t between 0.1 and 0.6. We compute the low-order statistical quantities including the total kinetic energy K (t), the dissipation rate ε (t), …

Middle School Parents' Perceptions Of Career And Technical Education, Virginia R. Powers Jones

STEMPS Theses & Dissertations

This study explored middle school parents' perceptions of the contributions career and technical education could make to their child's educational or workforce plans. It also examined what actions parents undertake to influence their child's plans, specifically the impact of the career exploration tool, Coin Career Community©, on their actions. Last, the study explored the correlation between the course choices students made in ninth grade relative to their parents' perceptions.

This study took place at Halifax County Middle School, located in South Boston, Virginia, in spring 2009. This school was the only middle school in the county with a student population …

Transformation Paradox: A Framework For The Analysis Of Politics In Enterprise Transformations, Cindy S. Miller

Engineering Management & Systems Engineering Theses & Dissertations

The purpose of this research is to develop a theoretical framework for the analysis of politics in enterprise transformations using a dialectical analysis approach (Hegel, 1989; Heraclitus, 1979; Pinkard, 1988; Skinner, 1978a, 1978b) and conduct an evaluation of the framework validity. The framework is constructed using a dialectical analysis of concepts stemming from the work of Alford and Friedland (1992) and considers four theoretical perspectives: autocratic, bureaucratic, pluralistic, and cognitive. The framework is then validated by means of qualitative metrics and adherence to critical ideology.

This research addresses the problem that there is no holistic theoretical framework for the analysis …

Ecology Of Neotropical Arboreal Snakes And Behavior Of New World Mollusk-Eating Snakes, Julie M. Ray

Biological Sciences Theses & Dissertations

The Neotropics is a biologically diverse region that provides man opportunities for ecological and behavioral studies. I utilized the speciose ophidian fauna of central Panama to explore the general ecology of arboreal snakes, the defensive behaviors of the snake community, and the diet of mollusk-eating snakes. I studied arboreal species to understand interspecilic relationships in several morphometric characters and to examine preferences in habitat. There were significant morphometric differences in relative length of jaw, mass, tail length, and size at midbody. The arboreal realm was partitioned among species by distance to ground, distance to water, and diameter of the perch. …

A Model Of Responses To Race-Based And Gender-Based Stereotype Threat In Computer Science, Lara Tedrow

Psychology Theses & Dissertations

The perception of stereotype threat among computer science students was examined at two universities. A model of stereotype threat was developed and tested among students enrolled in three undergraduate computer science courses at two universities. The goal of this model was to provide an understanding of the underlying mechanisms through which stereotype threat works.

The study tested relationships among the following variables: race-based stereotype threat, gender-based stereotype threat, goal orientation, CS self-efficacy, active coping, behavioral disengagement, effort, and performance. Structural equation modeling was used to test the measurement model and a series of nested structural models. Findings supported the proposed …

Biogenic Tracers Through The Holocene On The Alaskan Shelf, Carie A. Curry

OES Theses and Dissertations

Dramatic environmental changes in the Arctic Ocean have been observed for the last two decades including changing the amount of sea ice thickness and extent, and increased river discharge. In order to put these and other current day observations into historical context and perhaps reveal mechanisms controlling them, a suite of paleo-proxies were used to analyze two high resolution cores collected on the 2005 HOTRAX expedition. The goals of this research were: (1) develop an analytical method for determining biogenic calcite, (2) identify the major sources of biogenic matter into the system over the Holocene, and (3) assemble the history …

Efficacy Of Dual Enrollment In Rural Southwest Virginia, Karen Glass Carter

STEMPS Theses & Dissertations

The intent of this dissertation was to determine if enrollment into a career and technical education dual enrollment program encouraged students to continue their education into postsecondary education and if workplace readiness skills were increased. This study completed a factorial analysis of student demographic and factorial data as associated with the enrollment of career and technical education dual enrollment in rural, southwest Virginia. Specifically, the study explored secondary students (N = 221) currently enrolled during the academic school year 2008-2009 within a Virginia approved career and technical education dual enrollment course. These students attended one of four career and …

Emerging Workforce Trends And Issues Impacting The Virginia Community College System, Mary Greer Landon

Educational Leadership & Workforce Development Theses & Dissertations

The mission of the Virginia Community College workforce development leaders is to expand their training and development services to new and emerging high growth occupational areas in support of Virginia's economic growth and changing workforce needs in each of their regions. This research was designed to identify: high demand occupational skill needs; current training services; the shifting and changing trends based on technology, competition, and workforce composition; and the need for partnerships. A survey, based on current and emerging trends and their impact on workforce development training services, was sent to the 22 Virginia Community College workforce development leaders. This …

Is Seagrass An Important Nursery Habitat For The Caribbean Spiny Lobster, Panulirus Argus, In Florida?, Donald C. Behringer, Mark J. Butler Iv, William Herrnkind, John H. Hunt, Charles A. Acosta, William C. Sharp

Biological Sciences Faculty Publications

Caribbean spiny lobster (Panulirus argus) settle preferentially in macroalgal-covered hard-bottom habitat, but seagrass is more prevalent in Florida (United States) and the Caribbean, so even low settlement of lobsters within seagrass could contribute substantially to recruitment if post-settlement survival and growth were high. We tested the role of seagrass and hard-bottom habitats for P. argus recruitment in three ways. We first explored possible density-dependent regulation of early benthic juvenile lobster survival within cages deployed in seagrass and hard-bottom habitats. Second, we compared settlement and survival of P. argus in both habitats, by comparing the recovery of microwire-tagged early …

The Epidemiological Status Of Pav1, And The Effects Of Infection On Caribbean Spiny Lobster (Panulirus Argus) Condition, Olfaction, And Predation Risk, Donald C. Behringer, Mark J. Butler Iv, Jeffrey D. Shields

Biological Sciences Faculty Publications

No abstract provided.

Multiple Imputation To Correct For Measurement Error In Admixture Estimates In Genetic Structured Association Testing, Miguel A. Padilla, Jamin Divers, Laura K. Vaughan, David B. Allison, Hemant K. Tiwari

Psychology Faculty Publications

Objectives: Structured association tests ( SAT), like any statistical model, assumes that all variables are measured without error. Measurement error can bias parameter estimates and confound residual variance in linear models. It has been shown that admixture estimates can be contaminated with measurement error causing SAT models to suffer from the same afflictions. Multiple imputation (MI) is presented as a viable tool for correcting measurement error problems in SAT linear models with emphasis on correcting measurement error contaminated admixture estimates. Methods: Several MI methods are presented and compared, via simulation, in terms of controlling Type I error rates for both …

Obstacles In Investigating The Role Of Restructuring In Insightful Problem Solving, Ivan K. Ash, Patrick J. Cushen, Jennifer Wiley

Psychology Faculty Publications

In the present article, we articulate three assumptions underlying theories proposing that restructuring processes play a key role in insightful problem solving: representational difficulty, representational change, and discontinuity in solution processes. We argue that these assumptions need empirical validation to justify the proposition of restructuring mechanisms that are unique from those involved in classic information-processing theories of problem solving. To this end, we review some theoretical and methodological obstacles that are inherent in the investigation of the existence and nature of restructuring processes. We then offer some recommendations on how to overcome or avoid these obstacles in future studies. Finally, …

Dc Electrokinetic Transport Of Cylindrical Cells In Straight Microchannels, Ye Ai, Ali Beskok, David T. Gauthier, Sang W. Joo, Shizhi Qian

Biological Sciences Faculty Publications

Electrokinetic transport of cylindrical cells under dc electric fields in a straight microfluidic channel is experimentally and numerically investigated with emphasis on the dielectrophoretic (DEP) effect on their orientation variations. A two-dimensional multiphysics model, composed of the Navier-Stokes equations for the fluid flow and the Laplace equation for the electric potential defined in an arbitrary Lagrangian-Eulerian framework, is employed to capture the transient electrokinetic motion of cylindrical cells. The numerical predictions of the particle transport are in quantitative agreement with the obtained experimental results, suggesting that the DEP effect should be taken into account to study the electrokinetic transport of …

Part 1: The Regional Economy Contracts, Regional Studies Institute, Old Dominion University

State of the Region Reports: Hampton Roads

Defense spending continues to cushion our economic downturn, but two other major drivers, the port and tourism, have contracted. We also report stress tests for our major regional banks.

Understanding How Disease And Environment Combine To Structure Resistance In Estuarine Bivalve Populations, Eileen E. Hofmann, David Bushek, Susan E. Ford, Ximing Guo, Dale Haidvogel, Dennis Hedgecock, John M. Klinck, Coren Milbury, Diego Narvaez, Eric Powell, Yongping Wang, Zhiren Wang, Liusuo Zhang

CCPO Publications

Delaware Bay oyster (Crassostrea virginica) populations are influenced by two lethal parasites that cause Dermo and MSX diseases. As part of the US National Science Foundation Ecology of Infectious Diseases initiative, a program developed for Delaware Bay focuses on understanding how oyster population genetics and population dynamics interact with the environment and these parasites to structure he host populations, and how these interactions might modified by climate change. Laboratory and field studies undertaken during this program include identifying genes related to MSX and Dermo disease resistance, potential regions for refugia and the mechanisms that allow them to exist, …

Combining Remote Sensing Data And An Inundation Model To Map Tidal Mudflat Regions And Improve Flood Predictions: A Proof Of Concept Demonstration In Cook Inlet, Alaska, Tal Ezer, Hua Liu

CCPO Publications

Accurate flood predictions require high resolution inundation numerical models and detailed coastal and land topography data. However, such data are not always available. A new method to obtain topographic information of flood zones from remote sensing data is demonstrated here for Cook Inlet, Alaska, where tidal range reaches 8-10 m. The moving shoreline is detected from analysis of water coverage in satellite images taken at different tidal stages, and then the shoreline data from different times are combined with water level data from observations and models to produce new topographic maps of previously unobserved mudflats. The remote sensing-based analysis provides …

Variations In Sea Surface Roughness Induced By The 2004 Sumatra-Andaman Tsunami, O. A. Godin, V. G. Irisov, R. R. Leben, B. D. Hamlington, G. A. Wick

CCPO Publications

Observations of tsunamis away from shore are critically important for improving early warning systems and understanding of tsunami generation and propagation. Tsunamis are difficult to detect and measure in the open ocean because the wave amplitude there is much smaller than it is close to shore. Currently, tsunami observations in deep water rely on measurements of variations in the sea surface height or bottom pressure. Here we demonstrate that there exists a different observable, specifically, ocean surface roughness, which can be used to reveal tsunamis away from shore. The first detailed measurements of the tsunami effect on sea surface height …