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Old Dominion University

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2001

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Articles 1 - 30 of 51

Full-Text Articles in Physical Sciences and Mathematics

Dark Production: A Significant Source Of Oceanic Cos, M. Von Hobe, Gregory A. Cutter, A. J. Kettle, M. O. Andreae Dec 2001

Dark Production: A Significant Source Of Oceanic Cos, M. Von Hobe, Gregory A. Cutter, A. J. Kettle, M. O. Andreae

OES Faculty Publications

Carbonyl sulfide (COS) in air and dissolved in seawater was determined during a cruise in August 1999 in the Sargasso Sea in the northwest Atlantic Ocean. Dissolved concentrations at the sea surface displayed only a weak diel cycle with a mean of 8.6 ± 2.8 pmol dm−3 owing to low abundance of photochemical precursors and high temperatures causing rapid hydrolysis. Depth profiles measured over the oceanic mixed layer revealed significant vertical gradients of COS concentration with higher values at the surface, suggesting that the rate of photochemical production at the surface exceeds the rate of vertical mixing. The mean …

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The Standardized Fish Bioassay Procedure For Detecting And Culturing Actively Toxic Pfiesteria, Used By Two Reference Laboratories For Atlantic And Gulf Coast States, Joann M. Burkholder, Harold G. Marshall, David W. Seaborn, Nora J. Deamer-Melia Oct 2001

The Standardized Fish Bioassay Procedure For Detecting And Culturing Actively Toxic Pfiesteria, Used By Two Reference Laboratories For Atlantic And Gulf Coast States, Joann M. Burkholder, Harold G. Marshall, David W. Seaborn, Nora J. Deamer-Melia

Biological Sciences Faculty Publications

In the absence of purified standards of toxins from Pfiesteria species, appropriately conducted fish bioassays are the "gold standard" that must be used to detect toxic strains of Pfiesteria slop. from natural estuarine water or sediment samples and to culture actively toxic Pfiesteria. In this article, we describe the standardized steps of our fish bioassay as an abbreviated term for a procedure that includes two sets of trials with fish, following the Henle-Koch postulates modified for toxic rather than infectious agents. This procedure was developed in 1991, and has been refined over more than 12 years of experience in …

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Reconstructing Basin-Scale Eulerian Velocity Fields From Simulated Drifter Data, M. Toner, A. C. Poje, A. D. Kirwan, C. K. R. T. Jones, B. L. Lipphardt, C. E. Grosch Jan 2001

Reconstructing Basin-Scale Eulerian Velocity Fields From Simulated Drifter Data, M. Toner, A. C. Poje, A. D. Kirwan, C. K. R. T. Jones, B. L. Lipphardt, C. E. Grosch

CCPO Publications

A single-layer, reduced-gravity, double-gyre primitive equation model in a 2000 km x 2000 km square domain is used to test the accuracy and sensitivity of time-dependent Eulerian velocity fields reconstructed from numerically generated drifter trajectories and climatology. The goal is to determine how much Lagrangian data is needed to capture the Eulerian velocity field within a specified accuracy. The Eulerian fields are found by projecting, on an analytic set of divergence-free basis functions, drifter data launched in the active western half of the basin supplemented by climatology in the eastern domain. The time-dependent coefficients are evaluated by least squares minimization …

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Future Marine Zooplankton Research- A Perspective, Marine Zooplankton Colloquim 2, Eileen E. Hofmann, John M. Klinck Jan 2001

Future Marine Zooplankton Research- A Perspective, Marine Zooplankton Colloquim 2, Eileen E. Hofmann, John M. Klinck

CCPO Publications

During the Second Marine Zooplankton Colloquium (MZC2) 3 issues were added to those developed 11 yr ago during the First Marine Zooplankton Colloquium (MZC1). First, we focused on hot spots, i.e., locations where zooplankton occur in higher than regular abundance and/or operate at higher rates. We should be able to determine the processes leading to such aggregations and rates, and quantify their persistence. Second, information on the level of individual species, even of highly abundant ones, is limited. Concerted efforts should be undertaken with highly abundant to dominant species or genera (e.g., Oithona spp., Calanus spp., Oikopleura spp., Euphausia superba …

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Observations Of Intratidal Variability Of Flows Over A Sill/Contraction Combination In A Chilean Fjord, Arnoldo Valle-Levinson, Fernando Jara, Carlos Molinet, Doris Soto Jan 2001

Observations Of Intratidal Variability Of Flows Over A Sill/Contraction Combination In A Chilean Fjord, Arnoldo Valle-Levinson, Fernando Jara, Carlos Molinet, Doris Soto

CCPO Publications

Underway velocity measurements were carried out for the first time in a Chilean fjord using an acoustic Doppler velocimeter with the purpose of elucidating the intratidal variability of flows through a pass, Paso Galvarino. The pass included a sill, where the bottom sloped by roughly 30%, and a coastline contraction of -90%. The relatively small dimensions of the pass allowed for rapid sampling of the flow evolution throughout the tidal cycle. The backscattered sound signal from the velocimeter and from an echo sounder were used to describe the vertical excursions of the pycnocline throughout the domain and to identify regions …

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Wind And Gulf Stream Influences On Along-Shelf Transport And Off-Shelf Export At Cape Hatteras, North Carolina, Dana K. Savidge, John M. Bane Jr. Jan 2001

Wind And Gulf Stream Influences On Along-Shelf Transport And Off-Shelf Export At Cape Hatteras, North Carolina, Dana K. Savidge, John M. Bane Jr.

CCPO Publications

Along-shelf transports across three cross-shelf lines on the continental shelf near Cape Hatteras have been calculated from moored current meter data over a continuous 24 month period in 1992-1994. The along-shelf convergence has been used to infer off-shelf export. Transport and transport convergence have been related to wind and Gulf Stream forcing and to variability in sea level at the coast. The along-shelf transport variability is primarily wind-driven and highly correlated with sea level fluctuations at the coast. Both winds and along-shelf transport exhibit a near-annual period variability. Along shelf transport is not well correlated with Gulf Stream offshore position. …

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Future Research Vessels, Larry P. Atkinson Jan 2001

Future Research Vessels, Larry P. Atkinson

CCPO Publications

The academic research vessel fleet in the United States is embarking on a great experiment. By 2004 we will know if SWATH vessels such as the Mlo Moana and the possible built Woods Hole Oceanographic Institution coastal SWATH have such great advantages that all future vessels will be of SWATH design. Or, we will find that the two hull forms have distinct niches and the fleet will evolve with a strategic mix. Regardless of the Mure hull form research vessels will grow in size to accommodate advanced technology and the people to run and maintain it. The research vessel will …

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Comparison Of Statistical And Model-Based Hindcasts Of Subtidal Water Levels In Chesapeake Bay, Kathryn Thompson Bosley, Kurt W. Hess Jan 2001

Comparison Of Statistical And Model-Based Hindcasts Of Subtidal Water Levels In Chesapeake Bay, Kathryn Thompson Bosley, Kurt W. Hess

CCPO Publications

Subtidal water levels in Chesapeake Bay, which can have amplitudes as large as 1 m at Baltimore, are an important component of total water levels. The most importance forcing mechanisms for these variations are surface winds over the Bay and coastal subtidal water levels. Two methods for hindcasting subtidal water levels in the Bay were developed: statistical prediction (based on multiple linear regression) and a barotropic numerical circulation model-based prediction. The hindcast water levels were compared with the observed values at three key locations (Chesapeake Bay Bridge Tunnel (CBBT) in the lower bay near the mouth, Solomons Island at midbay, …

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Xenon Excimer Emission From Pulsed Microhollow Cathode Discharges, M. Moselhy, R. H. Stark, K. H. Schoenbach, U. Kogelschatz Jan 2001

Xenon Excimer Emission From Pulsed Microhollow Cathode Discharges, M. Moselhy, R. H. Stark, K. H. Schoenbach, U. Kogelschatz

Bioelectrics Publications

By applying electrical pulses of 20 ns duration to xenon microplasmas, generated by direct current microhollow cathode discharges, we were able to increase the xenon excimer emission by more than an order of magnitude over direct current discharge excimer emission. For pulsed voltages in excess of 500 V, the optical power at 172 nm was found to increase exponentially with voltage. Largest values obtained were 2.75 W of vacuum-ultraviolet optical power emitted from a single microhollow cathode discharge in 400 Torr xenon with a 750 V pulse applied to a discharge. Highest radiative emittance was 15.2 W/cm2. The …

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Electron Heating In Atmospheric Pressure Glow Discharges, Robert H. Stark, Karl H. Schoenbach Jan 2001

Electron Heating In Atmospheric Pressure Glow Discharges, Robert H. Stark, Karl H. Schoenbach

Bioelectrics Publications

The application of nanosecond voltage pulses to weakly ionized atmospheric pressure plasmas allows heating the electrons without considerably increasing the gas temperature, provided that the duration of the pulses is less than the critical time for the development of glow-to-arc transitions. The shift in the electron energy distribution towards higher energies causes a temporary increase in the ionization rate, and consequently a strong rise in electron density. This increase in electron density is reflected in an increased decay time of the plasma after the pulse application. Experiments in atmospheric pressure air glow discharges with gas temperatures of approximately 2000 K …

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Uptake Of Dissolved Organic Selenides By Marine Phytoplankton, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter Jan 2001

Uptake Of Dissolved Organic Selenides By Marine Phytoplankton, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter

OES Faculty Publications

Se is present in multiple oxidation states in nature, each of which has unique chemical and biological reactivities. As a consequence, the rate of Se incorporation into food webs or its role as either a limiting nutrient or a toxic substance is a function of complex biogeochemistry. In particular, little is understood about the accumulation of dissolved organic selenides by phyto- or bacterioplankton. We assessed the bioavailability of dissolved organic selenides to marine and estuarine phytoplankton by presenting various algal species with filtered lysates of the diatom, Thalassiosira pseudonana, grown on media amended with radiolabeled selenite (75Se[IV]). …

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Entropy Generation Method To Quantify Thermal Comfort, S. C. Boregowda, S. N. Tiwari, S. K. Chaturvedi Jan 2001

Entropy Generation Method To Quantify Thermal Comfort, S. C. Boregowda, S. N. Tiwari, S. K. Chaturvedi

Mechanical & Aerospace Engineering Faculty Publications

The present paper presents a thermodynamic approach to assess the quality of human-thermal environment interaction and quantify thermal comfort. The approach involves development of entropy generation term by applying second law of thermodynamics to the combined human-environment system. The entropy generation term combines both human thermal physiological responses and thermal environmental variables to provide an objective measure of thermal comfort. The original concepts and definitions form the basis for establishing the mathematical relationship between thermal comfort and entropy generation term. As a result of logic and deterministic approach, an Objective Thermal Comfort Index (OTCI) is defined and established as a …

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Can Long-Term Variability In The Gulf Stream Transport Be Inferred From Sea Level?, Tal Ezer Jan 2001

Can Long-Term Variability In The Gulf Stream Transport Be Inferred From Sea Level?, Tal Ezer

CCPO Publications

Recent studies by Sturges and collaborators suggest a simple, but powerful, technique to estimate climatic changes in the transport of the Gulf Stream from the difference between the oceanic sea level calculated with a simple wind-driven Rossby wave model and the observed coastal sea level. The hypothesis behind this technique is tested, using 40 years of data (1950 to 1989) obtained from a three-dimensional Atlantic Ocean model forced by observed surface data. The analysis shows that variations in sea level difference between the ocean and the coast are indeed coherent with variations of the Gulf Stream transport for periods shorter …

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Nested Balanced Incomplete Block Designs, J. P. Morgan, D. A. Preece, D. H. Rees Jan 2001

Nested Balanced Incomplete Block Designs, J. P. Morgan, D. A. Preece, D. H. Rees

Mathematics & Statistics Faculty Publications

If the blocks of a balanced incomplete block design (BIBD) with v treatments and with parameters (v; b1;r;k1) are each partitioned into sub-blocks of size k2, and the b2 =b1k1=k2 sub-blocks themselves constitute a BIBD with parameters (v; b2;r;k2), then the system of blocks, sub-blocks and treatments is, by de4nition, a nested BIBD (NBIBD). Whist tournaments are special types of NBIBD with k1 =2k2= 4. Although NBIBDs were introduced in the statistical literature in 1967 and have subsequently received occasional attention there, …

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Analysis Of Wine For Penicillin, Gary Morris, James Yuan, Roy Williams Jan 2001

Analysis Of Wine For Penicillin, Gary Morris, James Yuan, Roy Williams

Chemistry & Biochemistry Faculty Publications

This study addresses the question of whether the antibiotic Penicillin, which is produced by the common mold Penicillium notatum, could possibly become a contaminate of wine during the fermentation process. The significance of this study is related to the potential health effects this agent might produce in those consumers who have an allergic response to Penicillin. It has been estimated that between 6% and 8% of the American population is subject to this type of allergic response. A method is developed for the detection of penicillin in wines using high-pressure liquid chromatography. We demonstrate that penicillin G hydrolyzes rapidly …

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Stm And Electrochemical Investigation Of Homoepitaxial Boron-Doped Cvd Diamond Films, John B. Cooper, Jason A. Moulton, Sacharia Albin, Bing Xiao Jan 2001

Stm And Electrochemical Investigation Of Homoepitaxial Boron-Doped Cvd Diamond Films, John B. Cooper, Jason A. Moulton, Sacharia Albin, Bing Xiao

Chemistry & Biochemistry Faculty Publications

Homoepitaxial growth of boron-doped CVD diamond films was carried out on (100) and (111) oriented substrates. Atomic resolution images were obtained for both (100) and (111) surfaces using scanning tunneling microscopy. STM images reveal the presence of a 2x1-monohydride reconstruction for the untreated (100) surface and a lxl reconstruction for the untreated (111) surface. No other atomically resolved reconstructions were observed under a wide range of growth conditions. Non-aqueous electrochemical investigations were carried out on the films exhibiting atomically resolved reconstructions. Evidence for potential-induced surface-reconstruction and surface chemical modification of the (100) 2xl-monohydride surface has been observed.

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Resonant Energy Transfer From Argon Dimers To Atomic Oxygen In Microhollow Cathode Discharges, M. Moselhy, R. H. Stark, K. H. Schoenbach, U. Kogelschatz Jan 2001

Resonant Energy Transfer From Argon Dimers To Atomic Oxygen In Microhollow Cathode Discharges, M. Moselhy, R. H. Stark, K. H. Schoenbach, U. Kogelschatz

Bioelectrics Publications

The emission of atomic oxygen lines at 130.2 and 130.5 nm from a microhollow cathode discharge in argon with oxygen added indicates resonant energy transfer from argon dimers to oxygen atoms. The internal efficiency of the vacuum-ultraviolet (VUV) radiation was measured as 0.7% for a discharge in 1100 Torr argon with 0.1% oxygen added. The direct current VUV point source operates at voltages below 300 V and at current levels of milliamperes.

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Effective Field Theory For The Small-X Evolution, I. Balitsky Jan 2001

Effective Field Theory For The Small-X Evolution, I. Balitsky

Physics Faculty Publications

The small-x behavior of structure functions in the saturation region is determined by the non-linear generalization of the BFKL equation. I suggest the effective field theory for the small-x evolution which solves formally this equation. The result is the 2+1 functional integral for the structure functions at small x.

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Coherent-Path Model For Nuclear Resonant Scattering Of Gamma Radiation From Nuclei Excited By Synchrotron Radiation, Gilbert R. Hoy, Jos Odeurs, Romain Coussement Jan 2001

Coherent-Path Model For Nuclear Resonant Scattering Of Gamma Radiation From Nuclei Excited By Synchrotron Radiation, Gilbert R. Hoy, Jos Odeurs, Romain Coussement

Physics Faculty Publications

Previous theoretical descriptions of nuclear resonant scattering of synchrotron radiation have been based on the semiclassical optical model or on several quantum mechanical models. These models are fine but do not give a clear physical picture of all the processes. The theory presented here gives a clear physical picture of all the relevant aspects of nuclear resonant scattering. The model treats the nuclear resonant sample as a one-dimensional chain of "effective" nuclei. However, the model is deceptive. It only appears to be one dimensional. It actually treats the sample as a series of "effective" planes. The analysis uses the time-dependent …

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Gamma Echo Interpreted As A Phase-Shift Induced Transparency, Gilbert R. Hoy, Jos Odeurs Jan 2001

Gamma Echo Interpreted As A Phase-Shift Induced Transparency, Gilbert R. Hoy, Jos Odeurs

Physics Faculty Publications

In the gamma-echo technique a radioactive source is moved, with respect to a nuclear-resonant absorber, during the lifetime of first-excited nuclear state. This introduces a phase shift between the source radiation and the radiation from the absorber. If the source is moved abruptly, introducing a pi phase shift, the time-dependent intensity shows a sharp increase in the intensity at that time, the "gamma echo." Using the recently developed one-dimensional quantum-mechanical model, based on the technique developed by Heitler and Harris, the gamma-echo effect is seen to be a phase-shift-induced transparency. A closed-form solution for the time-dependent transmitted intensity has been …

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Electroproduction Of The Λ(1520) Hyperon, M. Bektasoglu, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, S. E. Kuhn, R. A. Niyazov, L. B. Weinstein, Et Al., The Clas Collaboration Jan 2001

Electroproduction Of The Λ(1520) Hyperon, M. Bektasoglu, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, S. E. Kuhn, R. A. Niyazov, L. B. Weinstein, Et Al., The Clas Collaboration

Physics Faculty Publications

The reaction e→pe′K+Λ(1520) with Λ(1520)→p′K− was studied at electron beam energies of 4.05, 4.25, and 4.46 GeV, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cos θK+, φK+, Q2, and W dependencies of Λ(1520) electroproduction are presented for the kinematic region 0.9 < Q2 < 2.4 GeV2 and 1.95 < W < 2.65 GeV. Also, the Q2 dependence of the Λ(1520) decay angular distribution is presented for the first time. The cosθK+ angular distributions suggest t-channel diagrams dominate the production process. Fits to the Λ(1520) t-channel helicity frame decay angular distributions indicate the m …

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The Ep → E'P Η Reaction At And Above The S₁₁ (1535) Baryon Resonance, R. Thompson, G. E. Dodge, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, R. A. Niyazov, L. M. Qin, L. B. Weinstein, Et Al., The Clas Collaboration Jan 2001

The Ep → E'P Η Reaction At And Above The S₁₁ (1535) Baryon Resonance, R. Thompson, G. E. Dodge, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, R. A. Niyazov, L. M. Qin, L. B. Weinstein, Et Al., The Clas Collaboration

Physics Faculty Publications

New cross sections for the reaction ep → ep η are reported for total center of mass energy W = 1.5-1.86 GeV and invariant momentum transfer Q2 = 0.25-1.5 (GeV/c)2. This large kinematic range allows extraction of important new information about response functions, photocouplings, and etaN coupling strengths of baryon resonances. Newly observed structure at W ~ 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

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Exclusive Electroproduction Of ᵠ Mesons At 4.2 Gev, M. Bektasoglu, L. Ciciani, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, F. Sabatié, L. B. Weinstein, Et Al., The Clas Collaboration Jan 2001

Exclusive Electroproduction Of ᵠ Mesons At 4.2 Gev, M. Bektasoglu, L. Ciciani, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, F. Sabatié, L. B. Weinstein, Et Al., The Clas Collaboration

Physics Faculty Publications

We studied the exclusive reaction ep → e' p' ᵠ using the ᵠ →K+K- decay mode. The data were collected using a 4.2 GeV incident electron beam and the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Our experiment covers the range in Q2 from 0.7 to 2.2 GeV2and W from 2.0 to 2.6 GeV. Taken together with all previous data, we find a consistent picture of ᵠ production on the proton. Our measurement shows the expected decrease of the t slope with the vector-meson formation time c Δ t …

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Top-Down Impact Through A Bottom-Up Mechanism. In Situ Effects Of Limpet Grazing On Growth, Light Requirements And Survival Of The Eelgrass Zostera Marina, Richard C. Zimmerman, Diana L. Steller, Donald G. Kohrs, Randall S. Alberte Jan 2001

Top-Down Impact Through A Bottom-Up Mechanism. In Situ Effects Of Limpet Grazing On Growth, Light Requirements And Survival Of The Eelgrass Zostera Marina, Richard C. Zimmerman, Diana L. Steller, Donald G. Kohrs, Randall S. Alberte

OES Faculty Publications

Temporal changes in abundance, size, productivity, resource allocation and light requirements of a subtidal eelgrass (Zostera marina L.) population were followed for 2 yr after the September 1993 appearance of a previously rare oval form of the commensal limpet Tectura depicta (Berry) in Monterey Bay, California, USA, By exclusively targeting the epidermis, limpet grazing impaired photosynthetic performance but left respiratory demand, meristematic growth and more than 90 % of the leaf biomass intact, The resulting low P:R ratios of grazed plants raised the light requirements for the maintenance of positive carbon balance almost 2-fold relative to healthy ungrazed plants …

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Iron In East Antarctic Snow: Implications For Atmospheric Iron Deposition And Algal Production In Antarctic Waters, Ross Edwards, Peter N. Sedwick Jan 2001

Iron In East Antarctic Snow: Implications For Atmospheric Iron Deposition And Algal Production In Antarctic Waters, Ross Edwards, Peter N. Sedwick

OES Faculty Publications

To evaluate the deposition and solubility of aerosol iron in the Antarctic seasonal sea ice zone (SSIZ), iron was measured in snow samples collected from three areas in the SSIZ (Prydz Bay, Dumont d'Urville Sea and Ross Sea) and one continental area (Princess Elizabeth Land) of East Antarctica. Concentrations of total-dissolvable iron (that soluble at pH ~2) ranged from 20-2950 pg g-1, with the lowest concentrations measured in snow from the Dumont d'Urville Sea. Using estimates of snow accumulation rates, we calculate atmospheric iron deposition fluxes of 0.017-0.11 mg m-2 yr-1(0.30-2.0 μmol m-2 yr …

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The Effect Of Spectral Composition On The Photochemical Production Of Hydrogen Peroxide In Lake Water, Andrea Y. L. Wong, George T. F. Wong Jan 2001

The Effect Of Spectral Composition On The Photochemical Production Of Hydrogen Peroxide In Lake Water, Andrea Y. L. Wong, George T. F. Wong

OES Faculty Publications

Hydrogen peroxide was produced when samples of lake water were exposed to direct or filtered sunlight in which UV or UV(B+C) light was selectively removed. In all cases, the concentration of hydrogen peroxide increased linearly with time-integrated irradiance. While both visible and UV light can induce the formation of hydrogen peroxide, the contribution from the latter was disproportionately large as it was responsible for about two-thirds of the formation of hydrogen peroxide. Among the UV lights, the contributions from UV-A and UV-(B+C) light were 70% and 30% respectively. The contribution from UV-A light was equivalent to about one half of …

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A Model To Evaluate The Effect Of Organizational Adaptation, Holly A. H. Handley, Alexander H. Levis Jan 2001

A Model To Evaluate The Effect Of Organizational Adaptation, Holly A. H. Handley, Alexander H. Levis

Engineering Management & Systems Engineering Faculty Publications

When an organization’s output declines due to either internal changes or changes in its external environment, it needs to adapt. In order to evaluate the effectiveness of different adaptation strategies on organizational per- formance, an organizational model composed of individual models of a five stage interacting decision maker was designed using an object oriented design approach and implemented as a Colored Petri net. The concept of entropy is used to calculate the total activity value, a surrogate for decision maker workload, based on the functional partition and the adaptation strategy being implemented. The individual decision maker’s total activity is monitored, …

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Meso-1, 2-Bis (Methylazo)-1, 2-Diphenylethane, Craig A. Bayse, Barry K. Carpenter, Rudy L. Luck Jan 2001

Meso-1, 2-Bis (Methylazo)-1, 2-Diphenylethane, Craig A. Bayse, Barry K. Carpenter, Rudy L. Luck

Chemistry & Biochemistry Faculty Publications

The title compound, meso-1,2-bis(methyldiazenyl)-1,2-diphenylethane, C16H18N4, is arranged in a disordered manner around an inversion point. The N—N atom distances in the azo group of 1.192 (8) and 1.195 (8) Å, and the C—C atom distances in the ethylene moiety at 1.512 (8) and 1.503 (8) Å in the two models [refined to 51.7 (6) and 48.3 (6)% occupancies] were not significantly different.

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Efficient Algorithms For Graphs With Few P-4’S, Luitpold Babel, Ton Kloks, Jan Kratochvíl, Dieter Kratsch, Kaiko Müller, Stephan Olariu Jan 2001

Efficient Algorithms For Graphs With Few P-4’S, Luitpold Babel, Ton Kloks, Jan Kratochvíl, Dieter Kratsch, Kaiko Müller, Stephan Olariu

Computer Science Faculty Publications

We show that a large variety of NP-complete problems can be solved efficiently for graphs with 'few' P4's. We consider domination problems (domination, total domination, independent domination. connected domination and dominating clique), the Steiner tree problem, the vertex ranking problem, the pathwidth problem, the path cover number problem, the hamiltonian circuit problem, the list coloring problem and the precoloring extension problem. We show that all these problems can be solved in linear time for the class of (q,q - 4)-graphs, for every fixed q. These are graphs for which no set of at most q. vertices induces more …

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Arc - An Oai Service Provider For Digital Library Federation, Xiaoming Liu, Kurt Maly, Mohammad Zubair, Michael L. Nelson Jan 2001

Arc - An Oai Service Provider For Digital Library Federation, Xiaoming Liu, Kurt Maly, Mohammad Zubair, Michael L. Nelson

Computer Science Faculty Publications

The usefulness of the many on-line journals and scientific digital libraries that exist today is limited by the inability to federate these resources through a unified interface. The Open Archive Initiative (OAI) is one major effort to address technical interoperability among distributed archives. The objective of OAI is to develop a framework to facilitate the discovery of content in distributed archives. In this paper, we describe our experience and lessons learned in building Arc, the first federated searching service based on the OAI protocol. Arc harvests metadata from several OAI compliant archives, normalizes them, and stores them in a search …

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