Physical Sciences and Mathematics Commons^™

Open-Ocean Carbon Monoxide Photoproduction, Aron Stubbins, Günther Uher, Cliff S. Law, Kenneth Mopper, Carol Robinson, Robert C. Upstill-Goddard

Chemistry & Biochemistry Faculty Publications

Sunlight-initiated photolysis of chromophoric dissolved organic matter (CDOM) is the dominant source of carbon monoxide (CO) in the open-ocean. A modelling study was conducted to constrain this source. Spectral solar irradiance was obtained from two models (GCSOLAR and SMARTS2). Water-column CDOM and total light absorption were modelled using spectra collected along a Meridional transect of the Atlantic ocean using a 200-cm pathlength liquid waveguide UV-visible spectrophotometer. Apparent quantum yields for the production of CO (AQY_CO) from CDOM were obtained from a parameterisation describing the relationship between CDOM light absorption coefficient and AQY_CO and the CDOM spectra collected. …

Plasma Emission Redistribution In A Single Cylce Of A Pulsed Dc Magnetron, W. Zhu, G. Buyle, J. Lopez, S. Shanmugmurthy, A. Belkind, K. Becker, R. De Gryse

Physics Faculty Publications

Time-resolved images of the optical emissions from a pulsed dc titanium target planar rectangular sputtering magnetron plasma were taken using Argon spectral filters and a Roper Scientific ICCD camera with a time resolution of 0.05-0.2 μs. At the beginning of the 'on-time', when the power is turned on, the discharge initially starts preferentially in two opposite curved sections ('cross corners') of the magnetron race track, where it exhibits the most intense plasma emissions. During the rest of the 'on-time', the emissions from the straight sections of the race track of the magnetron are always slightly more intense than the emissions …

Diffuse Light Scattering Dynamics Under Conditions Of Electromagnetically Induced Transparency, V. M. Datsyuk, I. M. Sokolov, D. V. Kupriyanov, M. D. Havey

Physics Faculty Publications

We show that under conditions of electromagnetically induced transparency (EIT) in an ultracold atomic sample in a magneto-optical trap, a significant portion of the incident probe pulse is transferred into Rayleigh and Raman scattering channels. The light scattered into the Rayleigh channel emerges from the sample with an EIT time delay. We show that a proper description of the probe light propagation in the sample should include, in the diffusion dynamics, a spin polariton generated by the two-photon EIT process. The results have important implications for studies of weak light localization and for manipulation of single and few photon states …

Erratum: Η' Photoproduction On The Proton For Photon Energies From 1.527 To 2.227 Gev (Phys. Rev. Lett. 96, Pg 062001, 2006), H. Bagdasaryan, M. Bektasoglu, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, L. M. Qin, F. Sabatié, L. B. Weinstein, Et Al., Clas Collaboration

Physics Faculty Publications

No abstract provided.

Response To "Comment On Variational Approach To The Volume Viscosity Of Fluids" [Phys. Fluids 18, 109101 (2006)], Allen J. Zuckerwar, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

We respond to the Comment of Markus Scholle and therewith revise our material entropy constraint to account for the production of entropy. (c) 2006 American Institute of Physics.

Constraints On The Nucleon Strange Form Factors At Q2 ∼ 0.1 Gev2, K. A. Aniol, D. S. Armstrong, T. Averett, H. Benaoum, P. Y. Bertin, E. Burtin, J. Cahoon, G. D. Cates, C. C. Chang, Y.-C. Chao, D. Deepa, H. Ibrahim

Mechanical & Aerospace Engineering Faculty Publications

We report the most precise measurement to date of a parity-violating asymmetry in elastic electron–proton scattering. The measurement was carried out with a beam energy of 3.03 GeV and a scattering angle (θ_lab) = 6.0○ , with the result A PV = ( − 1.14 ± 0.24 ( stat ) ± 0.06 ( syst ) ) × 10⁻⁶ . From this we extract, at Q² = 0.099 GeV² , the strange form factor combination G^s_E + 0.080 G^s_M = 0.030 ± 0.025 ( stat ) ± 0.006 ( syst ) ± …

A Tabu Search Algorithm To Minimize The Makespan For The Unrelated Parallel Machines Scheduling Problem With Setup Times, Magdy Helal, Ghaith Rabadi, Ameer Al-Salem

Engineering Management & Systems Engineering Faculty Publications

In this paper we propose a tabu search implementation to solve the unrelated parallel machines scheduling problem with sequence- and machine- dependent setup times to minimize the schedules makespan. The problem is NP-hard and finding an optimal solution efficiently is unlikely. Therefore, heuristic techniques are more appropriate to find near-optimal solutions. The proposed tabu search algorithm uses two phases of perturbation schemes: the intra-machine perturbation, which optimizes the sequence of jobs on the machines, and the inter-machine perturbation, which balances the assignment of the jobs to the machines. We compare the proposed algorithm to an existing one that addressed the …

Dynamics Of Carbon Allocation In A Deep-Water Population Of The Deciduous Kelp Pleurophycus Gardeneri (Laminariales), Clare M. Dominik, Richard C. Zimmerman

OES Faculty Publications

Pleurophycus gardneri (Laminariales) is common in the low intertidal of the Northeast Pacific, but dominates many deep (30 to 40 m) rocky reefs in central California. Seasonal dynamics of productivity and resource allocation of a deep-water population of this deciduous, stipitate kelp were studied to understand how blade abscission affects the annual carbon budget. Patterns of growth, metabolism, and carbon storage and mobilization were measured monthly for 1 yr relative to in situ light and temperature, and used to model the annual carbon budget. The resulting carbon budget was used to determine if blade abscission effectively reduced respiratory demand during …

The Role Of Lipids During Embryonic Development Of The Euphausiids Euphausia Pacifica And Thysanoessa Spinifera, Se-Jong Ju, H. Rodger Harvey, Jaime Gómez-Gutiérrez, William T. Peterson

OES Faculty Publications

To understand the role of lipids during early embryogenesis, major lipid classes together with individual fatty acid and sterol composition were determined in embryos from multiple developmental stages of the euphausiids Euphausia pacifica and Thysanoessa spinifera. Average lipid content in embryos of E. pacifica and T. spiniferafrom the earliest stage (multicell) were 4.45 and 3.69 µg embryo^-1,respectively. During development, the lipid content decreased at similar rates in the embryos of both species. In contrast to many crustacean eggs, phospholipids were the dominant lipid class in all embryonic stages, with decreasing concentrations seen during development. Individual …

Nitrogen Fixation And Release Of Fixed Nitrogen By Trichodesmium Spp. In The Gulf Of Mexico, Margaret R. Mulholland, Peter W. Bernhardt, Cynthia A. Heil, Deborah A. Bronk, Judith M. O'Neil

OES Faculty Publications

During a 3-yr study in the Gulf of Mexico, we measured dinitrogen (N₂) fixation and nitrogen (N) release by Trichodesmium and compared these rates with water column N demand and the estimated N necessary to support blooms of Karenia brevis, a toxic dinoflagellate that severely affects the West Florida shelf. Net and gross N₂ fixation rates were compared in simultaneous incubations using ¹⁵N₂ uptake and acetylene reduction, respectively. The difference between net and gross N₂ fixation is assumed to be an approximation of the rate of N release. Results demonstrate that Trichodesmium in …

Fedcor: An Institutional Cordra Registry, Giridhar Manepalli, Henry Jerez, Michael L. Nelson

Computer Science Faculty Publications

FeDCOR (Federation of DSpace using CORDRA) is a registry-based federation system for DSpace instances. It is based on the CORDRA model. The first article in this issue of D-Lib Magazine describes the Advanced Distributed Learning-Registry (ADL-R) [1], which is the first operational CORDRA registry, and also includes an introduction to CORDRA. That introduction, or other prior knowledge of the CORDRA effort, is recommended for the best understanding of this article, which builds on that base to describe in detail the FeDCOR approach.

Observed Web Robot Behavior On Decaying Web Subsites, Joan A. Smith, Frank Mccown, Michael L. Nelson

Computer Science Faculty Publications

We describe the observed crawling patterns of various search engines (including Google, Yahoo and MSN) as they traverse a series of web subsites whose contents decay at predetermined rates. We plot the progress of the crawlers through the subsites, and their behaviors regarding the various file types included in the web subsites. We chose decaying subsites because we were originally interested in tracking the implication of using search engine caches for digital preservation. However, some of the crawling behaviors themselves proved to be interesting and have implications on using a search engine as an interface to a digital library.

Splai: Computational Finite Element Model For Sensor Networks, Ruzana Ishak, Shadaruddin Salleh, Stephan Olariu, Mohd.Ismail Abdul Aziz

Computer Science Faculty Publications

Wireless sensor network refers to a group of sensors, linked by a wireless medium to perform distributed sensing task. The primary interest is their capability in monitoring the physical environment through the deployment of numerous tiny, intelligent, wireless networked sensor nodes. Our interest consists of a sensor network, which includes a few specialized nodes called processing elements that can perform some limited computational capabilities. In this paper, we propose a model called SPLAI that allows the network to compute a finite element problem where the processing elements are modeled as the nodes in the linear triangular approximation problem. Our model …

Synchronization And Multiple Group Server Support For Kepler, K. Maly, M. Zubair, H. Siripuram, S. Zunjarwad, Yannis Manolopoulos (Ed.), Joaquim Filipe (Ed.), Panos Constantopoulos (Ed.), José Cordeiro (Ed.)

Computer Science Faculty Publications

In the last decade literally thousands of digital libraries have emerged but one of the biggest obstacles for dissemination of information to a user community is that many digital libraries use different, proprietary technologies that inhibit interoperability. Kepler framework addresses interoperability and gives publication control to individual publishers. In Kepler, OAI-PMH is used to support "personal data providers" or "archivelets".". In our vision, individual publishers can be integrated with an institutional repository like Dspace by means of a Kepler Group Digital Library (GDL). The GDL aggregates metadata and full text from archivelets and can act as an OAI-compliant data provider …

A System Equivalence Related To Dulac's Extension Of Bendixson's Negative Theorem For Planar Dynamical Systems, Charlie H. Cooke

Mathematics & Statistics Faculty Publications

Bendixson's Theorem [H. Ricardo, A Modem Introduction to Differential Equations, Houghton-Mifflin, New York, Boston, 2003] is useful in proving the non-existence of periodic orbits for planar systems

dx/dt = F(x, y), dy/dt = G (x, y)

in a simply connected domain D, where F, G are continuously differentiable. From the work of Dulac [M. Kot, Elements of Mathematical Ecology, 2nd printing, University Press, Cambridge, 2003] one suspects that system (1) has periodic solutions if and only if the more general system

dx/d tau = B(x, y)F(x, y), dy/d tau = B(x, y)G(x, y)

does, which makes the subcase (1) more …

Hybrid Committee Classifier For A Computerized Colonic Polyp Detection System, Jiang Li, Jianhua Yao, Nicholas Petrick, Ronald M. Summers, Amy K. Hara, Joseph M. Reinhardt (Ed.), Josien P.W. Pluim (Ed.)

Electrical & Computer Engineering Faculty Publications

We present a hybrid committee classifier for computer-aided detection (CAD) of colonic polyps in CT colonography (CTC). The classifier involved an ensemble of support vector machines (SVM) and neural networks (NN) for classification, a progressive search algorithm for selecting a set of features used by the SVMs and a floating search algorithm for selecting features used by the NNs. A total of 102 quantitative features were calculated for each polyp candidate found by a prototype CAD system. 3 features were selected for each of 7 SVM classifiers which were then combined to form a committee of SVMs classifier. Similarly, features …

Electron Bernstein Wave Simulations And Comparison To Preliminary Nstx Emission Data, Josef Preinhaelter, Jakub Urban, Pavol Pavlo, Gary Taylor, Steffi Diem, Linda L. Vahala, George Vahala

Electrical & Computer Engineering Faculty Publications

Simulations indicate that during flattop current discharges the optimal angles for the aiming of the National Spherical Torus Experiment (NSTX) antennae are quite rugged and basically independent of time. The time development of electron Bernstein wave emission (EBWE) at particular frequencies as well as the frequency spectrum of EBWE as would be seen by the recently installed NSTX antennae are computed. The simulation of EBWE at low frequencies (e.g., 16 GHz) agrees well with the recent preliminary EBWE measurements on NSTX. At high frequencies, the sensitivity of EBWE to magnetic field variations is understood by considering the Doppler broadened electron …

Dynamics Of An Atmospheric Pressure Plasma Plume Generated By Submicrosecond Voltage Pulses, Xinpei Lu, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Nonequilibrium plasmas driven by submicrosecond high voltage pulses have been proven to produce high-energy electrons, which in turn lead to enhanced ionization and excitations. Here, we describe a device capable of launching a cold plasma plume in the surrounding air. This device, "the plasma pencil," is driven by few hundred nanosecond wide pulses at repetition rates of a few kilohertz. Correlation between current-voltage characteristics and fast photography shows that the plasma plume is in fact a small bulletlike volume of plasma traveling at unusually high velocities. A model based on photoionization is used to explain the propagation kinetics of the …

The Formal Laplace-Borel Transform Of Fliess Operators And The Composition Product, Yaqin Li, W. Steven Gray

Electrical & Computer Engineering Faculty Publications

The formal Laplace-Borel transform of an analytic integral operator, known as a Fliess operator, is defined and developed. Then, in conjunction with the composition product over formal power series, the formal Laplace-Borel transform is shown to provide an isomorphism between the semigroup of all Fliess operators under operator composition and the semigroup of all locally convergent formal power series under the composition product. Finally, the formal Laplace-Borel transform is applied in a systems theory setting to explicitly derive the relationship between the formal Laplace transform of the input and output functions of a Fliess operator. This gives a compact interpretation …

Growth Of Ge Quantum Dots On Si(100)-(2×1) By Pulsed Laser Deposition, M. S. Hegazy, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Self-assembled germanium quantum dots (QDs) were grown on Si(100)-(2×1) by pulsed laser deposition. In situ reflection-high energy electron diffraction (RHEED) and postdeposition atomic force microscopy are used to study the growth of the QDs. Several films of different thicknesses were grown at a substrate temperature of 400 °C using a Q-switched Nd:yttrium aluminum garnet laser (λ= 1064 nm, 40 ns pulse width, 23 J/cm ² fluence, and 10 Hz repetition rate). At low film thicknesses, hut clusters that are faceted by different planes, depending on their height, are observed after the completion of the wetting layer. With increasing film thickness, …

A Dyadic Composition To Foster Virtual Team Effectiveness: An Experimental Study, Gamze Karayaz

Engineering Management & Systems Engineering Theses & Dissertations

The importance of effectiveness for virtual teamwork continues to gain momentum as technology and globalization of work accelerate. The implementation of virtual teams provides one approach to enhance competitiveness, overcoming the disadvantages of space and time differences through collaborative technologies. The influence of structure to virtual team performance has not been clearly established in the literature. The purpose of this research study was to investigate the effectiveness of a dyad structured approach for virtual teams using a quasi-experimental research design.

This research investigated four questions related to the influence of structure on virtual team effectiveness related to task performance, communication …

On The Existence Of Strong Solutions To Autonomous Differential Equations With Minimal Regularity, Charlie H. Cooke

Mathematics & Statistics Faculty Publications

For proving the existence and uniqueness of strong solutions to

dY/dt = F(Y), Y(0) = C,

the most quoted condition seen in elementary differential equations texts is that F(Y) and its first derivative be continuous. One wonders about the existence of a minimal regularity condition which allows unique strong solutions. In this note, a bizarre example is seen where F(Y) is not differentiable at an equilibrium solution; yet unique non-global strong solutions exist at each point, whereas global non-unique weak solutions are allowed. A characterizing theorem is obtained.

Vertical Distribution Of Decapod Larvae In The Entrance Of An Equatorward Facing Bay Of Central Chile: Implications For Transport, Beatriz Yannicelli, Leonardo R. Castro, Arnoldo Valle-Levinson, Larry Atkinson, Dante Figueroa

CCPO Publications

Two short biophysical surveys were carried out in order to assess how the decapod crustacean larvae vertical distribution and circulation patterns in an equatorward facing embayment (Gulf of Arauco, 37° S; 73° W) influenced larval transport into and out of the Gulf. The embayment is located at the upwelling area of south central Chile and features a deep (60 m) and a shallow (25 m) pathway of communication with the adjacent coastal ocean. Profiles of zooplankton, temperature, salinity, dissolved oxygen and current velocity were measured during a 22-h period at the shallow entrance to the gulf. In addition, three zooplankton …

Lattice Quantum Algorithm For The Schrodinger Wave Equation In 2+1 Dimensions With A Demonstration By Modeling Soliton Instabilities, Jeffrey Yepez, George Vahala, Linda L. Vahala

Electrical & Computer Engineering Faculty Publications

A lattice-based quantum algorithm is presented to model the non-linear Schrödinger-like equations in 2 + 1 dimensions. In this lattice-based model, using only 2 qubits per node, a sequence of unitary collide (qubit-qubit interaction) and stream (qubit translation) operators locally evolve a discrete field of probability amplitudes that in the long-wavelength limit accurately approximates a non-relativistic scalar wave function. The collision operator locally entangles pairs of qubits followed by a streaming operator that spreads the entanglement throughout the two dimensional lattice. The quantum algorithmic scheme employs a non-linear potential that is proportional to the moduli square of the wave function. …

Radar - A Novel Admission Control And Handoff Management Scheme For Multimedia Leo Satellite Networks, Syed Rashidali Rizvi

Computer Science Theses & Dissertations

Low Earth Orbit (LEO) satellite networks are deployed as an enhancement to terrestrial wireless networks in order to provide broadband services to users regardless of their location. In addition to global coverage, these satellite systems support communications with hand-held devices and offer low cost-per-minute access cost, making them promising platforms for Personal Communication Services (PCS). LEO satellites are expected to support multimedia traffic and to provide their users with some form of Quality of Service (QoS) guarantees. However, the limited bandwidth of the satellite channel, satellite rotation around the Earth and mobility of end-users makes QoS provisioning and mobility management …

Robust And Efficient Localization Techniques For Cellular And Wireless Sensor Networks, Haseebulla M. Khan

Computer Science Theses & Dissertations

Localization in wireless networks refers to a collection of tasks that, collectively, determines the location of a mobile user, striving to hide the effects of mobility from the user and/or application. Localization has become an important issue and has drawn considerable attention, as many applications including E-911, cargo tracking, locating patients, location-sensitive billing, etc., require knowledge of the location of user/objects. It was realized, quite a while back, that extending emergency 911-like services (E-911) to continually growing mobile population is one of the extremely important localization applications. The bulk of the proposed solutions to emergency location management in wireless environments …

Alignment Dynamics Of Slow Light Diffusion In Ultracold Atomic 85Rb, S. Balik, R. G. Olave, C. I. Sukenik, M. D. Havey, V. M. Datsyuk, I. M. Sokolov, D. V. Kupriyanov

Physics Faculty Publications

A combined experimental and theoretical investigation of time- and alignment-dependent propagation of light in an ultracold atomic gas of atomic ⁸⁵Rb is reported. Coherences among the scattering amplitudes for light scattering off excited hyperfine levels produce strong variations of the light polarization in the vicinity of atomic resonance. Measurements are in excellent agreement with Monte Carlo simulations of the multiple scattering process.

Assessment Of Human Health Risks From Chemically Contaminated Lake Fishes In Greece, Eugene G. Maurakis, David V. Grimes, Dimitra Bobori, Rob Hale, Jennifer Jones

Virginia Journal of Science

Objectives were to conduct screening level surveys of locally consumed fish tissues in vicinities of two lakes (Kastoria and Pamvotis) in Greece to determine the presence of halogenated organic compounds and determine carcinogenic and non-carcinogenic human health risks associated with the consumption of sampled fish tissues. Results estimate the Incremental Lifetime Cancer Risks (ILCR) and Hazard Index (HI) values for the two local populations using site-specific population data. These results were compared to analyses conducted using U.S. Environmental Protection Agency default values in an effort to determine the applicability of USEPA default values to assessments of risks in non U.S. …

Circulation, Vol. 12, No. 2, Center For Coastal Physical Oceanography, Old Dominion University, Marjorie Friedrichs

CCPO Circulation

Fall 2005 issue of CCPO Circulation featuring article "The Regional Ecosystem Modeling Testbed Project" by Dr. Marjorie Friedrichs

Characterization Of Pfiesteria Ichthyocidal Activity, Andrew S. Gordon, Harold G. Marshall, Sandra E. Shumway, Kathryn J. Coyne, Alan J. Lewitus, Michael A. Mallin, Parke A. Rublee

Biological Sciences Faculty Publications

Letter to the Editor regarding article: Drgon, T., et al. 2005. Characterization of ichthyocidal activity of Pfiesteria piscicida: Dependence on the dinospore cell density. Appl. Environ. Microbiol. 71:519–529