Physical Sciences and Mathematics Commons^™

Direct Measurements Of Two Photon Exchange On Lepton-Proton Elastic Scattering Using Simultaneous Electron-Positron Beams In Clas, Dasuni Kalhari Adikaram

Physics Theses & Dissertations

The electric (GE) and magnetic ( GM) form factors of the proton are fundamental observables which characterize its charge and magnetization distributions. There are two methods to measure the proton form factors: the Rosenbluth separation method and the polarization transfer technique. However, the ratio of the electric and magnetic form factors measured by those methods significantly disagree at momentum transfer Q² > 1 GeV². The most likely explanation of this discrepancy is the inclusion of two-photon exchange (TPE) amplitude contributions to the elastic electron-proton cross section which significantly changes the extraction of GE from the …

Modeling And Simulation Of Shape Changes Of Red Blood Cells In Shear Flow, John Gounley

Mathematics & Statistics Theses & Dissertations

A description of the biomechanical character of red blood cells is given, along with an introduction to current computational schemes which use deformable capsules to simulate red blood cell shape change. A comprehensive two- and three-dimensional framework for the fluid-structure interaction between a deformable capsule and an ambient flow is provided. This framework is based on the immersed boundary method, using lattice Boltzmann and finite element methods for the fluid and structure, respectively. The characteristic response and recovery times of viscoelastic circular and spherical capsules are compared, and their dependence on simulation parameters is shown. The shape recovery of biconcave …

Computational Solutions Of The Forward And Adjoint Euler Equations With Application To Duct Aeroacoustics, Ibrahim Kocaogul

Mathematics & Statistics Theses & Dissertations

Traditionally, the acoustic source terms are modeled by single frequency sinusoidal functions. In the present study, the acoustic sources are modeled by a broadband wave packet. Radiation of acoustic waves at all frequencies can be obtained by Time Domain Wave Packet (TDWP) method in a single time domain computation. The TDWP method is also particularly useful for computations in the ducted or waveguide environments where incident wave modes can be imposed cleanly without a potentially long transient period. Theoretical analysis as well as numerical validation are performed in this study. In addition, the adjoint equations for the linearized Euler equations …

Analyzing Cholera Dynamics In Homogeneous And Heterogeneous Environments, Drew Posny

Mathematics & Statistics Theses & Dissertations

Cholera continues to be a serious public health concern in developing countries and the global increase in the number of reported outbreaks suggests that activities to control the diseases and surveillance programs to identify or predict the occurrence of the next outbreaks are not adequate. Mathematical models play a critical role in predicting and understanding disease mechanisms, and have long provided basic insights in the possible ways to control infectious diseases. This dissertation is concerned with mathematical modeling and analysis of cholera dynamics. First, we study an autonomous model in a homogeneous environment with added controls that involves both direct …

Ray- And Wave-Theoretic Approach To Electromagnetic Scattering From Radially Inhomogeneous Spheres And Cylinders, Michael A. Pohrivchak

Mathematics & Statistics Theses & Dissertations

With applications in the areas of chemistry, physics, microbiology, meteorology, radar, astronomy, and many other fields, electromagnetic scattering is an important area of research. Many everyday phenomena that we experience are a result of the scattering of electromagnetic and acoustic waves. In this dissertation, the scattering of plane electromagnetic waves from radially inhomogeneous spheres and cylinders using both ray- and wave-theoretic principles is considered. Chapters 2 and 3 examine the use of the ray approach. The deviation undergone by an incident ray from its original direction is related to the angle through which the radius vector turns from the point …

Markov Chain Monte Carlo Bayesian Predictive Framework For Artificial Neural Network Committee Modeling And Simulation, Michael S. Goodrich

Computational Modeling & Simulation Engineering Theses & Dissertations

A logical inference method of properly weighting the outputs of an Artificial Neural Network Committee for predictive purposes using Markov Chain Monte Carlo simulation and Bayesian probability is proposed and demonstrated on machine learning data for non-linear regression, binary classification, and 1-of-k classification. Both deterministic and stochastic models are constructed to model the properties of the data. Prediction strategies are compared based on formal Bayesian predictive distribution modeling of the network committee output data and a stochastic estimation method based on the subtraction of determinism from the given data to achieve a stochastic residual using cross validation. Performance for Bayesian …

Section Abstracts: Computer Science

Virginia Journal of Science

Abstracts of the Computer Science Section for the 92nd Annual Meeting of the Virginia Academy of Science, May 13-15, 2014, Virginia Commonwealth University, Richmond, Virginia

Growth And Nitrogen Uptake Kinetics In Cultured Procentrum Donghaiense, Zhangxi Hu, Shunshan Duan, Margaret R. Mulholland

OES Faculty Publications

We compared growth kinetics of Prorocentrum donghaiense cultures on different nitrogen (N) compounds including nitrate, ammonium urea, glutamic acid, dialanine, and cynate. P. donghaiense exhibited standard Monod-type growth kinetics over a range of nitrogen concentrations for all N. Compounds tested. Cultures grown on glu and urea had the highest maximum growth rates. However, cultures grown on cyanate had lower half saturation constants. Nitrogen uptake kinetics were measured in nitrate-deplete and replete batch cultures of P. donghaiense. In nitrate-deplete batch cultures, P. donghaiense exhibited Michaelis-Menten type uptake kinetics for nitrate, ammonium, urea and algal amino acids; uptake was saturated at …

Section Abstracts: Statistics

Virginia Journal of Science

Abstracts of the Statistics Section for the 92nd Annual Meeting of the Virginia Academy of Science, May 13-15, 2014, Virginia Commonwealth University, Richmond, Virginia

Assessing The Impact Of Electronic Health Record Systems Implementation On Hospital Patient Perceptions Of Care, Katherine Sofia Palacio Salgar

Engineering Management & Systems Engineering Theses & Dissertations

The delivery of health care services has been impacted by advances in Knowledge Management Information Systems (KMIS) and Information Technology (IT). The literature reveals that Electronic Health Records Systems (EHRs) are a comprehensive KMIS. There is a wide recognition in the body of knowledge that demonstrates the potential of EHRs to transform all aspects of health care services and, in consequence, the performance of Health Care Delivery Organizations (HCDO). Authors of published research also agree that there is a need for more empirical contributions that demonstrate the impact of EHRs upon HCDO. It is argued that in most cases, studies …

Simulation Modeling And Analysis Of Customs-Regulated Container Terminal Operations With Multimodal Transportation, Mariam A. Kotachi

Engineering Management & Systems Engineering Theses & Dissertations

World trade has been increasing dramatically in the past two decades and, as a result, container exchange has grown significantly. Consequently and to meet this increase, several container terminals are expanding and many new ones are being established. A port with one or more container terminals is considered a complex system in which many entities interact to accomplish seamless handling of containers inbound and outbound. The level of complexity is drastically heightened for container terminals containing multimodal transportation systems as they typically involve ships, rail, and trucks arriving to one or more terminals delivering containers of different sizes to several …

Assessing Organizational Effectiveness Through The Competing Values Framework A Data Envelopment Approach, Raghavender Macherla

Engineering Management & Systems Engineering Theses & Dissertations

This study proposes a model to diagnose organizations using the mathematical principles of data envelopment analysis (DEA) to the variables generated using competing values framework (CVF) in order to evaluate overall organizational effectiveness. The notion of organizational effectiveness is abstract and difficult to measure due to its complexity and multi-functional nature. Over the years, measurement of organizational effectiveness has remained a challenge due to the lack of agreement on the factors that should be assessed to determine effectiveness. This research is aimed at shedding some light into this topic by using data envelopment analysis as a tool to measure relative …

Transparent Spectrum Co-Access In Cognitive Radio Networks, Jonathan Daniel Backens

Electrical & Computer Engineering Theses & Dissertations

The licensed wireless spectrum is currently under-utilized by as much as 85%. Cognitive radio networks have been proposed to employ dynamic spectrum access to share this under-utilized spectrum between licensed primary user transmissions and unlicensed secondary user transmissions. Current secondary user opportunistic spectrum access methods, however, remain limited in their ability to provide enough incentive to convince primary users to share the licensed spectrum, and they rely on primary user absence to guarantee secondary user performance. These challenges are addressed by developing a Dynamic Spectrum Co-Access Architecture (DSCA) that allows secondary user transmissions to co-access transparently and concurrently with primary …

Modeling Stem Cell Population Dynamics, Samiur Arif

Computer Science Theses & Dissertations

Because of the stochastic nature of biological systems, mathematical and computational modeling approaches have become more acceptable to experimentalists and clinicians in recent years as contributing to new understandings of complicated cell mechanisms and tissue physiology. Indeed, even single cell or small tissue samples are complex dynamic systems that adapt to environmental challenges in space and time which is poorly understood. Mathematical models and computer simulations can explain and uncover unknown aspects of cell behavior and tissue functions. Models based on key biological mechanisms can give interesting insights and formulate predictions that cannot be derived from physical experiments or statistical …

A Collaborative International Research Program On The Coupled North Atlantic-Arctic System: Science Plan, Eileen E. Hoffmann, Mike St. John, Heather M. Benway

CCPO Publications

This North Atlantic-Arctic science plan is derived from an international workshop held in April 2014 with support from the National Science Foundation Division of Ocean Sciences and the European Union (EU). The workshop was designed to facilitate development of a core vision for advancing the next phase of research on the North Atlantic-Arctic system and strengthening international collaborations within and between the EU and North America.

Agenda, Hr Adaptation Forum

March 28, 2014: Addressing Current and Future Vulnerability through Floodplain Management

No abstract provided.

Fema Region Iii Coastal Flood Study - Hampton Roads Adaptation Forum, Robin Danforth

March 28, 2014: Addressing Current and Future Vulnerability through Floodplain Management

No abstract provided.

Floodplain Management Ordinance: Virginia Beach, Whitney Mcnamara

March 28, 2014: Addressing Current and Future Vulnerability through Floodplain Management

No abstract provided.

The Community Rating System And Sea Level Rise Adaptation, Shannon Hulst

March 28, 2014: Addressing Current and Future Vulnerability through Floodplain Management

No abstract provided.

Improved Line Data For The Swan System 12c13c Isotopologue, Ram S. Ram, James S. A. Brooke, Peter F. Bernath, Christopher Sneden, Sara Lucatello

Chemistry & Biochemistry Faculty Publications

We present new, accurate predictions for rotational line positions, excitation energies, and transition probabilities of the ¹²C ¹³C isotopologue Swan d³Π-a³Π system 0-0, 0-1, 0-2, 1-0, 1-1, 1-2, 2-0, 2-1, and 2-2 vibrational bands. The line positions and energy levels were predicted through new analyses of published laboratory data for the ¹²C¹³C lines. Transition probabilities were derived from recent computations of transition dipole moments and related quantities. The ¹²C¹³C line data were combined with similar data for ¹²C₂, reported in a companion paper, and applied …

Geotraces: Changing The Way We Explore Ocean Chemistry, Robert F. Anderson, Edward Mawji, Gregory A. Cutter, Christopher I. Measures, Catherine Jeandel

OES Faculty Publications

GEOTRACES is an international study of the marine biogeochemical cycles of trace elements and their isotopes (TEIs), designed by marine geochemists to accelerate TEI research under a global program. Combining ocean sections, process studies, data synthesis, and modeling, GEOTRACES will identify and quantify the processes that supply TEIs at ocean boundaries as well as the physical and biological processes that redistribute TEIs within and between ocean basins. Constraining processes that remove TEIs from the ocean will enable complete mass budgets to be generated. Anticipated beneficiaries of GEOTRACES products include scientists studying the sustained health of marine ecosystems and their sensitivity …

The Effects Of Changing Winds And Temperatures On The Oceanography Of The Ross Sea In The 21st Century, Walker O. Smith, Michael S. Dinniman, Eileen E. Hofmann, John M. Klinck

CCPO Publications

The Ross Sea is critically important in regulating Antarctic sea ice and is biologically productive, which makes changes in the region's physical environment of global concern. We examined the effects of projected changes in atmospheric temperatures and winds on aspects of the ocean circulation likely important to primary production using a high-resolution sea ice-ocean-ice shelf model of the Ross Sea. The modeled summer sea-ice concentrations decreased by 56% by 2050 and 78% by 2100. The duration of shallow mixed layers over the continental shelf increased by 8.5 and 19.2days in 2050 and 2100, and the mean summer mixed layer depths …

Rums: Research For Undergraduates In Math And Science, David Gauthier

Undergraduate Research Symposium

Chair: Dr. David Gauthier, Department of Biological Sciences

Presenters: Elizabeth Smith, Jessica Vincent, Amarilis Dyer, Amy Johnson, Joseph Brown

Facets Of Physical Sciences, Stephen Bueltmann

Undergraduate Research Symposium

Chair: Dr. Stephen Bueltmann, Department of Physics

Presenters: Colton Katsarelis, Katheryne McMahan, Timothy Naginey, James Porter, Eric Stacy

Hurricane Preparedness: Community Vulnerability And Medically Fragile Populations, Joshua G. Behr, Rafael Diaz

VMASC Publications

No abstract provided.

Einstein A Coefficients And Oscillator Strengths For The A 2Π-X2Σ+ (Red) And B 2Σ+-X2Σ+ (Violet) Systems And Rovibrational Transitions In The X2Σ+ State Of Cn, James S. A. Brooke, Ram S. Ram, Colin M. Western, Gang Li, David W. Schwenke, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

Line strengths have been calculated in the form of Einstein A coefficients and f-values for a large number of bands of the A ²Π-X ²Σ⁺ and B ²Σ⁺-X ²Σ⁺ systems and rovibrational transitions within the X ²Σ⁺ state of CN using Western's PGOPHER program. The J dependence of the transition dipole moment matrix elements (the Herman-Wallis effect) has been taken into account. Rydberg-Klein-Rees potential energy functions for the A ²Π, B ²Σ⁺ , and X ²Σ⁺ states were computed using spectroscopic constants from the …

Beam-Energy Dependence Of The Directed Flow Of Protons, Antiprotons, And Pions In Au+Au Collisions, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, I. Koralt, Star Collaboration

Physics Faculty Publications

Rapidity-odd directed flow (v1) measurements for charged pions, protons, and antiprotons near midrapidity (y= 0) are reported in √ˢᴺᴺ = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeVAu+Au collisions as recorded by the STAR detector at the Relativistic Heavy Ion Collider. At intermediate impact parameters, the proton and net-proton slope parameter d v₁/ d y│_y=0 shows a minimum between 11.5 and 19.6 GeV. In addition, the net-proton d v₁/ d y│_y=0 changes sign twice between 7.7 and 39 GeV. The proton and net-proton results qualitatively resemble predictions …

Energy Dependence Of Moments Of Net-Proton Multiplicity Distributions At Rhic, L. Adamczyk, J. K. Adkins, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

We report the beam energy (√ˢᴺᴺ = 7.7-200 GeV) and collision centrality dependence of the mean (M), standard deviation (σ), skewness (S), and kurtosis (κ) of the net-proton multiplicity distributions in Au + Au collisions. The measurements are carried out by the STAR experiment at midrapidity (|y| < 0.5) and within the transverse momentum range 0.4 < p_T < 0.8 GeV/c in the first phase of the Beam Energy Scan program at the Relativistic Heavy Ion Collider. These measurements are important for understanding the quantum chromodynamic phase diagram. The products of the moments, Sσ and Kσ², are sensitive to the correlation length of the hot and dense medium created in the collisions and are related to the ratios of baryon number susceptibilities of corresponding orders. The products of moments are found to have values significantly below the Skellam expectation and close to expectations based on independent …

Measurement Of The Target-Normal Single-Spin Asymmetry In Deep-Inelastic Scattering From The Reaction ³He↑(E,E')X, J. Katich, X. Qian, X. Y. Zhao, M. Canan, L. El Fassi, S. Golge

Physics Faculty Publications

We report the first measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the inclusive reaction ³He↑(e, e')X on a polarized ³He gas target. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation but can be nonzero if two-photon-exchange contributions are included. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.7 < W < 2.9 GeV, 1.0 < Q² < 4.0 GeV² and 0.16 < x < 0.65. Neutron asymmetries were extracted using the effective nucleon polarization and measured proton-to-³He cross-section ratios. The measured neutron asymmetries are negative with an average value of (-1.09 ± 0.38) x 10^-2for invariant mass W > 2 GeV, which is nonzero at …

J/Ψ Production At Low Pᵀ In Au + Au And Cu + Cu Collisions At √ˢᴺᴺ = 200 Gev With The Star Detector, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, I. Koralt, Star Collaboration

Physics Faculty Publications

The J/ψ p_T spectrum and nuclear modification factor (R_AA) are reported for p_T < 5 GeV/c and |y| < 1 from 0% to 60% central Au + Au and Cu + Cu collisions at √ˢᴺᴺ = 200 GeV at STAR. A significant suppression of p_T - integrated J/ψ production is observed in central Au + Au events. The Cu + Cu data are consistent with no suppression, although the precision is limited by the available statistics. R_AA in Au + Au collisions exhibits a strong suppression at low transverse momentum and gradually increases with p_T. The data are compared to high-p_T STAR results and previously published BNL Relativistic Heavy Ion Collider results. Comparing with model calculations, it is found that the invariant yields …